Cylinder head with built-in oil return channel

Abstract

The application provides a cylinder cover with built-in oil return channels under the condition that the cylinder cover push rod hole is arranged on the exhaust side and the cylinder cover top plate exhaust side is higher than the intake side; the application solves the problem of normal return of lubricating oil to the oil sump by designing the oil return channels at the front and rear ends of the cylinder cover without changing the diesel engine body, reduces the development cost of the diesel engine, reduces the heat conduction of the cooling water of the upper water jacket to the intake port and the heat radiation of the exhaust port to the lubricating oil by introducing the oil return structure of the application, improves the intake capacity and power density of the diesel engine, effectively prolongs the maintenance period of the lubricating oil, and improves the power and reliability of the diesel engine.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine technology, specifically to a cylinder head with a built-in oil return channel. Background Technology

[0002] The cylinder head is the core component of the entire diesel engine. Many high-speed rotating parts are arranged on the upper part of the cylinder head, such as pushrod ball joint, rocker arm, rocker arm shaft, and bridge arm. In order to reduce the wear of moving parts, lubricating oil is needed to lubricate the moving parts. The lubricating oil flows through the cylinder head to the rocker arm shaft, then to the rocker arm ball joint, pushrod, etc., and finally flows back to the oil pan for recycling.

[0003] Currently, the cylinder head arrangement of domestic diesel engines generally involves the intake and exhaust sides being on different sides, with the pushrod holes located on the exhaust side. The intake side of the cylinder head top plate is higher than the exhaust side. This ensures that the lubricating oil on the cylinder head flows back to the crankcase along the pushrod holes and then back to the oil pan. A few diesel engines have the cylinder head pushrod holes located on the intake side. This necessitates the redesign and development of the engine block, gear system, camshaft, etc., resulting in higher overall product development costs and poor product compatibility, making it only suitable for newly developed products.

[0004] Currently, the intake air temperature after turbocharging and intercooling in diesel engines is generally 60℃-70℃, while the water temperature of the cylinder head water jacket is generally 80℃-95℃. For most diesel engines with pushrod holes located on the exhaust side, the intake side of the cylinder head top plate must be higher than the exhaust side so that the lubricating oil can return smoothly to the oil pan. If the intake side of the cylinder head top plate is higher than the exhaust side, the upper part of the intake manifold will be filled with water chambers, causing the water in the cylinder head water jacket to heat the intake manifold, thus increasing the intake air temperature. This affects the combustion in the engine cylinder and is not conducive to improving the power output of the diesel engine.

[0005] Generally, the exhaust side temperature of a diesel engine is higher. When lubricating oil returns from the exhaust pushrod hole, it heats the lubricating oil in the exhaust manifold, causing it to deteriorate and shortening the lubricating oil maintenance cycle. Conversely, if the intake side is higher than the exhaust side, air bubbles will form on the cylinder head on the intake side. The thermostat outlet must be located on the front face of the cylinder head or the intake side, resulting in a larger overall cylinder head size and poor compatibility. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a cylinder head with a built-in oil return channel, ensuring that the cylinder head pushrod holes are located on the exhaust side and the exhaust side of the cylinder head top plate is higher than the intake side. While maintaining the same cylinder head length, this invention solves the problem of normal lubricating oil return to the oil pan by designing oil return channels at the front and rear ends of the cylinder head. This eliminates the need to modify the diesel engine block, reducing diesel engine development costs. Furthermore, by introducing the oil return structure of this invention, the heat conduction from the upper water jacket's cooling water to the intake manifold and the heat radiation from the exhaust manifold to the lubricating oil are reduced, thereby increasing the diesel engine's intake volume and power density, effectively extending the lubricating oil maintenance cycle, and improving the diesel engine's power and reliability.

[0007] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0008] A cylinder head with a built-in oil return channel includes a cylinder head body. The cylinder head body has an intake passage on one side and an exhaust passage on the other side. The cylinder head body is divided into four cylinders from front to back, from the first to the fourth. Each cylinder is equipped with an exhaust passage and two intake passages. Each exhaust passage has an intake valve pushrod hole and an exhaust valve pushrod hole on its front side. The intake valve pushrod hole is located on the side of the exhaust valve pushrod hole away from the exhaust passage.

[0009] The cylinder head body is provided with a stepped cylinder head top plate, the exhaust side of the cylinder head top plate is higher than the intake side, and the cylinder head top plate and the cylinder head vertical wall form an oil sump.

[0010] The cylinder head body has a front oil return channel inside the front end and a rear oil return channel inside the rear end, both of which penetrate the top and bottom surfaces of the cylinder head body. One end of the front oil return channel is connected to the oil sump, and the other end is connected to the intake valve pushrod hole at the front end. Lubricating oil flows into the front oil return channel through the oil sump and then flows to the crankcase through the intake valve pushrod hole. One end of the rear oil return channel is connected to the oil sump, and the other end is connected to the exhaust valve pushrod hole at the rear end. Lubricating oil flows into the rear oil return channel through the oil sump and then flows to the crankcase through the exhaust valve pushrod hole.

[0011] Furthermore, both the intake and exhaust passages are located below the oil sump, with the outer wall of the intake passage completely fitting the bottom wall of the cylinder head top plate, and a water passage forming between the exhaust passage and the cylinder head top plate.

[0012] Furthermore, a cylinder bolt joint is provided between two adjacent cylinders, and a guide plate is provided at the cylinder bolt joint between the third and fourth cylinders, so that the lubricating oil of the first to third cylinders flows into the crankcase of the engine block through the front oil return channel, while the lubricating oil of the fourth cylinder flows into the crankcase of the engine block through the rear oil return channel. At the same time, while ensuring the strength of the cylinder head and meeting the contact stress of the cylinder head bolt flange surface, the cylinder bolt joints located between the first and second cylinders and between the second and third cylinders are thinned, so that the oil return cross section gradually increases during the process of lubricating oil returning to the front oil return channel, so as to ensure smooth oil return in the oil sump.

[0013] Furthermore, the cylinder head body is also provided with a front sealing bolt assembly for the cover, a rear sealing bolt assembly for the cover, a thermostat housing fixing bolt assembly, an exhaust pipe fixing bolt assembly, a front locating pin assembly for the bottom surface of the cylinder head, and a rear locating pin assembly for the bottom surface of the cylinder head.

[0014] Furthermore, the minimum local cross-sectional area of ​​the aforementioned front return oil channel is not less than 380 mm². 2 This is to ensure smooth oil return in the front return channel.

[0015] Furthermore, the height of the return oil chamber in the front return oil channel is not less than 20mm.

[0016] Furthermore, the minimum local cross-sectional area of ​​the rear oil return channel is not less than 260 mm². 2 This is to ensure smooth oil return in the subsequent return channel.

[0017] Furthermore, the thermostat inlet is located on the exhaust side of the cylinder head body.

[0018] Beneficial effects:

[0019] (1) The present invention casts a front oil return channel on the front end face and a rear oil return channel on the rear end face of the cylinder head body, which solves the problem that the lubricating oil cannot return to the oil pan due to the exhaust side of the cylinder head top plate being higher than the intake side and the push rod hole being arranged on the exhaust side. Through the two oil return channels on the front and rear of the cylinder head body, the lubricating oil can smoothly return to the oil pan when the engine is tilted forward and backward.

[0020] (2) This invention avoids the design and development of components such as diesel engine block, gear system, and camshaft, resulting in low overall product development costs and good product compatibility. At the same time, the diesel engine oil return channel is realized through casting, which reduces the cylinder head processing cost.

[0021] (3) The present invention introduces front and rear oil return channels, which can make the intake side of the cylinder head top plate as low as possible. In extreme cases, the cylinder head top plate and the intake passage share the same wall, so that there is no cooling water above the intake passage, which reduces the heat radiation of the water in the upper water jacket to the intake passage, improves the cooling effect of the water flow of the upper water jacket to the exhaust passage, increases the intake volume of the engine, and thus increases the power density of the engine and improves the engine power performance.

[0022] (4) The present invention designs a guide plate in the cylinder head oil sump so that as much lubricating oil as possible returns to the oil pan from the front return oil passage, avoiding the heating of the lubricating oil by the exhaust passage, solving the problem of lubricating oil deterioration due to high temperature, extending the maintenance cycle of lubricating oil, and improving engine reliability.

[0023] (5) The thermostat inlet of the present invention is designed on the exhaust side, which effectively reduces the overall volume of the cylinder head, reduces the overall weight of the engine, and improves the compatibility with diesel engines. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a partial view of the top surface of the cylinder head in this invention.

[0026] Figure 2 yes Figure 1 Sectional view at point BB.

[0027] Figure 3 yes Figure 1 Sectional view at EE.

[0028] Figure 4 yes Figure 1 Sectional view at FF.

[0029] Figure 5 This is a partial cross-sectional view of the guide vane 23 in this invention.

[0030] Figure 6 It is a sectional view of the front return oil channel parallel to the front end face.

[0031] Figure 7 It is a sectional view of the rear return oil channel parallel to the rear end face.

[0032] Figure 8 This is a schematic diagram of the sand core assembly in this invention.

[0033] Figure 9 This is the bottom view of the top surface sand core in this invention.

[0034] Figure 10 This is a top view of the bottom sand core in this invention.

[0035] Figure 11 This is a front view of the sand core of the front return oil channel in this invention.

[0036] Figure 12 This is a bottom view of the sand core of the front return oil channel in this invention.

[0037] Figure 13 yes Figure 12 Sectional view at point GG.

[0038] Figure 14 This is a front view of the sand core of the back oil return channel in this invention.

[0039] Figure 15 This is a bottom view of the sand core of the back oil return channel in this invention.

[0040] Figure 16 yes Figure 15 Sectional view at point KK.

[0041] Illustration markings: 1. Cylinder head body; 2. Front oil return passage; 3. Oil sump; 4. Rear oil return passage; 5. Cylinder head top plate; 6. Cylinder head vertical wall; 7. Cover sealing surface; 8. Intake valve pushrod hole; 9. Exhaust valve pushrod hole; 10. Inter-cylinder bolt joint; 11. Thermostat inlet; 12. Water passage; 13. Front sealing bolt joint of cover; 14. Rear sealing bolt joint of cover; 15. Thermostat housing fixing bolt joint; 16. Exhaust pipe fixing bolt joint; 17. Front locating pin joint of cylinder head bottom surface; 18. Rear locating pin joint of cylinder head bottom surface; 19. Intake manifold; 20. Exhaust manifold; 21. Front oil return sand core; 22. Rear oil return sand core; 23. Baffle plate; 24. Front cover surface clearance. 25. Recessed area of ​​the front sealing bolt of the cover; 26. Recessed area of ​​the thermostat housing fixing bolt; 27. Partial recessed area of ​​the rear locating pin of the cylinder head bottom surface; 28. Recessed area of ​​the sealing surface of the rear cover; 29. ​​Recessed area of ​​the sealing bolt of the cover rear end; 30. Recessed area of ​​the exhaust pipe fixing bolt; 31. Cylinder head top surface sand core; 32. Cylinder head bottom surface sand core; 33. Front locating hole of the top surface sand core; 34. Rear locating hole of the top surface sand core; 35. Front locating hole of the bottom surface sand core; 36. Rear locating hole of the bottom surface sand core; 37. Upper locating core head of the front oil return sand core; 38. Lower locating core head of the front oil return sand core; 39. Upper locating core head of the rear oil return sand core; 40. Lower locating core head of the rear oil return sand core. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. It is obvious that the described embodiments are only part, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] The present invention provides a cylinder head with a built-in oil return channel, please refer to Figures 1 to 7 , the cylinder head is provided with a cylinder head body 1, and the cylinder head body 1 comprises a front oil return channel 2, an oil sump 3, a rear oil return channel 4, a cylinder head top plate 5, a cylinder head vertical wall 6, a cover sealing surface 7, an intake valve push rod hole 8, an exhaust valve push rod hole 9, an inter-cylinder bolt boss 10, a cover front end sealing bolt boss 13, a cover rear end sealing bolt boss 14, a thermostat housing fixing bolt boss 15, an exhaust pipe fixing bolt boss 16, a cylinder head bottom surface front positioning pin boss 17, a cylinder head bottom surface rear positioning pin boss 18, an intake port 19 and an exhaust port 20. The exhaust port 20 is arranged on the exhaust side of the cylinder head body 1, and the intake port 19 is arranged on the intake side of the cylinder head body 1. The interior of the cylinder head body 1 is divided into four cylinder compartments from front to rear, namely the first to the fourth cylinder compartments, each cylinder compartment is provided with one exhaust port 20 and two intake ports 19, and a intake valve push rod hole 8 and a exhaust valve push rod hole 9 are arranged on the front side of each exhaust port 20, wherein the intake valve push rod hole 8 is located on a side of the exhaust valve push rod hole 9 away from the exhaust port 20. The cylinder head body 1 is provided with a stepped cylinder head top plate 5, the exhaust side of the cylinder head top plate 5 is higher than the intake side, and the cylinder head top plate 5 and the cylinder head vertical wall 6 enclose the oil sump 3; the front oil return channel 2 is arranged inside the front end of the cylinder head body 1, the rear oil return channel 4 is arranged inside the rear end of the cylinder head body 1, and both the front and rear oil return channels penetrate through the top surface and the bottom surface of the cylinder head body 1; wherein, one end of the front oil return channel 2 is connected with the oil sump 3, and the other end is connected with the intake valve push rod hole 8 at the foremost end; lubricating oil flowing out from components such as rocker arms and rocker arm shafts converges into the oil sump 3 by virtue of the slope of the cylinder head top plate 5, then flows into the front oil return channel 2, and then flows to the engine block crankcase through the intake valve push rod hole 8; one end of the rear oil return channel 4 is connected with the oil sump 3, and the other end is connected with the exhaust valve push rod hole 9 at the rearmost end; lubricating oil flowing out from components such as rocker arms and rocker arm shafts converges into the oil sump 3 by virtue of the slope of the cylinder head top plate 5, then flows into the rear oil return channel 4, and then flows to the engine block crankcase through the exhaust valve push rod hole 9.

[0044] The specific structure of the cylinder head body 1 will be elaborated in detail below.

[0045] The cylinder head top plate 5 is generally stepped, and comprises a lower section located on the intake side, an upper section located on the exhaust side and an inclined section connecting the two; the cylinder head top plate 5 gradually rises from the intake side to the exhaust side, the oil sump 3 is arranged above the cylinder head top plate 5, and the intake port 19 and the exhaust port 20 are both arranged below the cylinder head top plate 5.

[0046] like Figure 4 As shown, the oil sump 3 consists of a cylinder head top plate 5 and a cylinder head vertical wall 6. The width of the cylinder head vertical wall 6 is determined by the width of the cover sealing surface 7 (the cover sealing surface is the side of the cylinder head body 1 that contacts the cover). To ensure the sealing effect of the cover, the width of the cover sealing surface 7 should not be less than 7mm, that is, the width E of the cylinder head vertical wall 6 ≥ 7mm. To reduce the heat conduction of cooling water to the intake manifold 19, the cylinder head top plate 5 is completely fitted to the outer wall of the intake manifold 19, and there is no cooling water between the intake manifold 19 and the cylinder head top plate 5. The oil sump 3 is located above the intake manifold 19. Figure 2 As shown, a water passage 12 is formed between the cylinder head top plate 5 and the exhaust port 20, so that the water in the upper water jacket is distributed as much as possible around the exhaust port 20, reducing the heat conduction of the water in the water jacket to the intake port 19. The exhaust side of the cylinder head top plate 5 is higher than the intake side, so the lubricating oil flowing out through the rocker arm, rocker arm shaft and other components can collect in the oil sump 3 along the inclined section of the cylinder head top plate 5.

[0047] To facilitate technical personnel's understanding of the technical solution, the casting sand core used in the cylinder head body 1 and its casting process will be described first. For example... Figures 11-13 As shown, the front oil return channel 2 is formed by an independent front oil return sand core 21. The front oil return sand core 21 is provided with an upper positioning core head 37 and a lower positioning core head 38, wherein the diameter D of the upper positioning core head 37 and the lower positioning core head 38 is ≥ 8mm. Figures 14-16 As shown, the rear oil channel 2 is formed by an independent rear oil return sand core 22. The sand core 22 is equipped with an upper positioning core 39 and a lower positioning core 40 for the rear oil return sand core. The core diameter D' of the upper positioning core 39 and the lower positioning core 40 for the rear oil return sand core is ≥8mm. Figures 9-10 As shown, the cylinder head top surface sand core 31 is provided with a front positioning hole 33 and a front and rear positioning hole 34, and the cylinder head bottom surface sand core 32 is provided with a front positioning hole 35 and a rear positioning hole 36. Figure 8 As shown, during the casting process, the positioning core head 37 of the front oil return sand core is inserted into the front positioning hole 33 of the top sand core, the positioning core head 38 of the front oil return sand core is inserted into the front positioning hole 35 of the bottom sand core, the positioning core head 39 of the rear oil return sand core is inserted into the rear positioning hole 34 of the top sand core, and the positioning core head 40 of the rear oil return sand core is inserted into the rear positioning hole 36 of the bottom sand core. Through the combination of the core heads and positioning holes, the front oil return sand core 21, the rear oil return sand core 22, the cylinder head top sand core 31, and the cylinder head bottom sand core 32 are assembled together for casting. Increasing the positioning of the core heads avoids the problem of core drift during casting, improves casting accuracy, ensures the uniformity and sealing of the wall thickness of the front and rear oil return channels, and reduces the scrap rate of cylinder head casting.

[0048] like Figures 1-7 As shown, one end of the front oil return channel 2 is connected to the oil sump 3, and the other end is connected to the intake valve push rod hole 8. One end of the rear oil return channel 4 is connected to the oil sump 3, and the other end is connected to the exhaust valve push rod hole 9. Figures 6-7 As shown, lubricating oil flows through the oil sump 3 into the front and rear return oil channels, and then flows through the corresponding push rod holes to the crankcase. Figures 2-3 As shown, the intake valve push rod hole 8 is farther away from the exhaust passage 20, while the exhaust valve push rod hole 9 is closer to the exhaust passage 20, in order to reduce the heat radiation of the exhaust passage 20 to the lubricating oil. Meanwhile, to further reduce the heat radiation of the exhaust manifold 20 to the lubricating oil and to allow as much lubricating oil as possible to flow back to the engine crankcase from the front return oil passage 2 through the intake valve pushrod hole 8, this invention provides a guide plate 23 at the cylinder bolt joint 10 between the third and fourth cylinders. This allows the lubricating oil from the first to third cylinders to flow into the engine crankcase through the front return oil passage 2, and the lubricating oil from the fourth cylinder to flow into the engine crankcase through the rear return oil passage 4. Simultaneously, while ensuring the strength of the cylinder head body 1 and meeting the contact stress of the cylinder head bolt flange surface, the cylinder bolt joints between the first and second cylinders, and between the second and third cylinders, are locally thinned. This gradually increases the return oil cross-section in the oil sump 3, i.e., the return oil cross-sectional area F > G > H, ensuring smooth oil return in the oil sump and allowing the lubricating oil to flow as much as possible into the front return oil passage 2 and then back to the diesel engine oil pan. Figure 2 As shown, the height J of the oil return chamber of the front oil return channel 2 is ≥20mm, ensuring that a small amount of lubricating oil passing through the front oil return channel 2 is at a certain distance from the exhaust channel 20, thus avoiding the exhaust channel 20 from heating the lubricating oil.

[0049] like Figures 11-16 As shown, the front and rear oil return channels are formed by the front oil return sand core 21 and the rear oil return sand core 22. In order to ensure the strength of the sand core, the thickness A of the front oil return sand core 21 and the rear oil return sand core 22 is ≥15mm, the width B is ≥20mm, and the local wall thickness H is ≥20mm. By limiting the parameters of the front oil return sand core 21 and the rear oil return sand core 22, the oil return channels meet the requirements on the one hand, and the core strength is guaranteed on the other hand. The front oil return core 21 is provided with a front cover sealing clearance recess 24, a cover front sealing bolt clearance recess 25, and a thermostat housing fixing bolt clearance recess 26. The rear oil return core 22 is provided with a cylinder head bottom surface rear locating pin clearance recess 27, a rear cover sealing surface clearance recess 28, a cover rear sealing bolt clearance recess 29, and an exhaust pipe fixing bolt clearance recess 30. In other words, the front and rear oil return channels are also provided with corresponding clearance flanges to ensure that the front and rear oil return channels are in a sealed space, so that there is no leakage during the process of lubricating oil returning to the crankcase. After increasing the local clearance, the local minimum cross-sectional area S1 of the front oil return core 21 is ≥380mm.2 The minimum local cross-sectional area S2 of the rear oil return sand core 22 is ≥260mm. 2 That is, the local minimum cross-sectional area S1 of the front return oil channel 2 is ≥380mm. 2 The minimum local cross-sectional area S2 of the return oil channel 4 is ≥ 260 mm. 2 This ensures smooth oil return in the front and rear oil return channels 2 and 4.

[0050] Furthermore, the thermostat inlet 11 is designed on the exhaust side, which can both avoid the front oil return passage 2 and reduce the cylinder head volume.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A cylinder head with a built-in oil return channel, comprising a cylinder head body, characterized in that, The cylinder head body has an intake passage on one side and an exhaust passage on the other side. The cylinder head body is divided into four cylinders from front to back, from the first to the fourth. Each cylinder is equipped with an exhaust passage and two intake passages. Each exhaust passage has an intake valve pushrod hole and an exhaust valve pushrod hole on its front side. The intake valve pushrod hole is located on the side of the exhaust valve pushrod hole away from the exhaust passage. The cylinder head body is provided with a stepped cylinder head top plate, the exhaust side of the cylinder head top plate is higher than the intake side, and the cylinder head top plate and the cylinder head vertical wall form an oil sump. The cylinder head body has a front oil return channel inside the front end and a rear oil return channel inside the rear end, both of which penetrate the top and bottom surfaces of the cylinder head body. One end of the front oil return channel is connected to the oil sump, and the other end is connected to the intake valve pushrod hole at the front end. Lubricating oil flows into the front oil return channel through the oil sump and then flows to the crankcase through the intake valve pushrod hole. One end of the rear oil return channel is connected to the oil sump, and the other end is connected to the exhaust valve pushrod hole at the rear end. Lubricating oil flows into the rear oil return channel through the oil sump and then flows to the crankcase through the exhaust valve pushrod hole. Inter-cylinder bolt joints are provided between two adjacent cylinders, and guide plates are provided at the inter-cylinder bolt joints between the third and fourth cylinders. This allows the lubricating oil from the first to third cylinders to flow into the crankcase of the engine block through the front return oil channel, while the lubricating oil from the fourth cylinder flows into the crankcase of the engine block through the rear return oil channel. At the same time, while ensuring the strength of the cylinder head and meeting the contact stress of the cylinder head bolt flange surface, the inter-cylinder bolt joints located between the first and second cylinders and between the second and third cylinders are thinned. This allows the return oil cross-section to gradually increase as the lubricating oil returns to the front return oil channel, ensuring smooth oil return in the oil sump.

2. A cylinder head with a built-in oil return channel according to claim 1, characterized in that, Both the intake and exhaust manifolds are located below the oil sump. The outer wall of the intake manifold is completely flush with the bottom wall of the cylinder head top plate, and a water passage is formed between the exhaust manifold and the cylinder head top plate.

3. A cylinder head with a built-in oil return channel according to claim 1, characterized in that, The cylinder head body is also provided with a front sealing bolt assembly for the cover, a rear sealing bolt assembly for the cover, a thermostat housing fixing bolt assembly, an exhaust pipe fixing bolt assembly, a front locating pin assembly for the bottom surface of the cylinder head, and a rear locating pin assembly for the bottom surface of the cylinder head.

4. A cylinder head with a built-in oil return channel according to claim 1, characterized in that, The minimum local cross-sectional area of ​​the front return oil channel is not less than 380 mm². 2 .

5. A cylinder head with a built-in oil return channel according to claim 1, characterized in that, The height of the return oil chamber in the front return oil channel shall not be less than 20mm.

6. A cylinder head with a built-in oil return channel according to claim 1, characterized in that, The minimum local cross-sectional area of ​​the rear oil return channel is not less than 260 mm². 2 .

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