A cylinder head sand core structure, positioning and assembling method and cylinder head

Abstract

The application belongs to the technical field of cylinder head casting, and discloses a cylinder head sand core structure, a cylinder head and an engine, which comprise a base sand core and an exhaust side sand core; the exhaust side sand core comprises, from bottom to top, a lower water jacket sand core, a lower exhaust passage sand core, a middle water jacket sand core, an upper exhaust passage sand core and an upper water jacket sand core which are sequentially assembled on the base sand core; the lower water jacket sand core and the lower exhaust passage sand core are respectively positioned and matched with the base sand core through corresponding concave-convex positioning structures; the upper exhaust passage sand core is positioned and matched with the lower exhaust passage sand core through a corresponding concave-convex positioning structure; the lower water jacket sand core, the middle water jacket sand core and the upper water jacket sand core are fixed with each other through front end positioning structures and rear end positioning structures; and the upper exhaust passage sand core is fixedly connected with the upper water jacket sand core through positioning mechanisms in an interference fit. The multiple sand core positioning structures satisfy the mutual positioning between the multiple sand cores, guarantee the positioning accuracy, reserve sufficient fault tolerance space and reduce the risk of sand core fracture.

Description

Technical Field

[0001] This invention belongs to the field of cylinder head casting technology, specifically relating to a cylinder head sand core structure and positioning assembly method, and a cylinder head. Background Technology

[0002] As engine performance continues to improve, the cylinder head, as one of the most complex and thermally demanding core components of an engine, directly impacts its reliability, durability, and emissions levels. To enhance cooling efficiency, the exhaust side of the cylinder head has become increasingly complex, typically integrating intricate intake manifold and water jacket structures. The water jacket, in particular, is designed to closely surround the exhaust manifold to maximize cooling efficiency, with the most complex designs evolving into three-layer structures. This complex water jacket structure, intertwined with the upper and lower exhaust manifold structures, significantly increases the structural complexity of the exhaust-side core, placing extremely stringent demands on its manufacturing and positioning precision.

[0003] In the prototyping stage of cylinder heads, using 3D-printed sand cores for prototype manufacturing has become a common practice in the industry to shorten the development cycle and reduce mold costs. Given the complex structure of the exhaust side, existing technologies typically employ a solution of integral 3D-printed sand cores for the exhaust side, combining multiple sand cores such as the intake manifold core, exhaust manifold core, lower water jacket core, and upper water jacket core into a single integral sand core for printing. Integral 3D-printed sand cores effectively avoid the cumulative errors caused by the mating of multiple sand cores, ensuring better dimensional consistency of the exhaust manifold and water jacket sand cores. The dimensional accuracy of 3D-printed sand cores can reach ±0.3mm, with a uniform and dense structure and stable strength.

[0004] However, the monolithic 3D-printed sand core solution also has significant limitations in practical applications. First, the complex internal structure and narrow channels of a monolithic sand core make cleaning residual molding sand extremely difficult after casting. Second, monolithic sand cores lack tolerance during casting; any defects or fractures in a single area will render the entire core unusable, increasing trial production costs and risks. Therefore, in the cylinder head trial production stage, disassembling the exhaust-side sand core into multiple core structures remains the preferred technical approach.

[0005] However, multi-core structures inevitably bring about positioning and fitting problems between sand cores. Multiple sand cores need to be positioned and assembled one by one during assembly, and the positioning accuracy between sand cores directly affects the final dimensional accuracy of the casting. Especially when some sand cores are manufactured using traditional hand-making and others using 3D printing, the dimensional deviations and differences in positioning benchmarks caused by different manufacturing processes pose a greater challenge to the positioning and fitting of the sand cores. If the positioning structure between sand cores is not designed properly, problems such as inaccurate positioning and misalignment of sand cores will occur during assembly. Sand core positioning deviations will directly cause unstable gas passage wall thickness and substandard dimensional accuracy in the casting after casting; at the same time, poor positioning may also lead to uneven stress on the sand cores during mold closing or pouring, resulting in fractures, severely restricting production continuity and yield.

[0006] In summary, how to rationally design the positioning structure between multiple sand cores while ensuring the dimensional accuracy of the exhaust side air passage and water jacket sand core, solve the problem of matching and positioning between handmade sand cores and 3D printed sand cores, and avoid defects such as casting dimensional deviations and sand core breakage caused by unreasonable positioning has become an urgent technical problem to be solved in the cylinder head trial production stage. Summary of the Invention

[0007] This invention provides a cylinder head sand core structure and positioning assembly method, and a cylinder head.

[0008] The specific details of the plan are as follows: A cylinder head sand core structure includes a base sand core and an exhaust-side sand core. The exhaust-side sand core includes, from bottom to top, a lower water jacket sand core, a lower exhaust manifold sand core, a middle water jacket sand core, an upper exhaust manifold sand core, and an upper water jacket sand core, all mounted sequentially on the base sand core. The lower water jacket sand core and the lower exhaust manifold sand core are respectively positioned and engaged with the base sand core through their respective concave-convex positioning structures. The upper exhaust manifold sand core is positioned and engaged with the lower exhaust manifold sand core through its corresponding concave-convex positioning structure. The lower water jacket sand core, the middle water jacket sand core, and the upper water jacket sand core are mutually fixed through a front-end positioning structure and a rear-end positioning structure. The upper exhaust manifold sand core is fixedly connected to the upper water jacket sand core through an interference fit of the concave-convex positioning structure.

[0009] Furthermore, in the positioning structure of each sand core, there is an assembly gap between the matching protrusions and recesses. The base sand core is provided with a positioning groove for the lower water jacket sand core. The peripheral wall of the positioning groove for the lower water jacket sand core forms a limiting cavity that is "U"-shaped when viewed from above. Multiple positioning protrusions are provided at intervals in the middle area at the bottom of the limiting cavity. The bottom of the lower water jacket sand core is provided with a positioning recess that matches the multiple positioning protrusions. The bottom of the lower water jacket sand core is fitted into the limiting cavity, and the multiple positioning protrusions extend into the corresponding positioning recesses.

[0010] Furthermore, a first square positioning protrusion is provided on the top end face of the lower water jacket sand core positioning groove on the base sand core, and a first square upper recess is provided on the bottom end face of the lower exhaust channel sand core that matches the first square positioning protrusion. The lower exhaust channel sand core is positioned on the base sand core through the concave-convex cooperation between the first square upper recess and the first square positioning protrusion.

[0011] Furthermore, the top end face of the lower exhaust channel sand core is provided with a second square positioning protrusion, and the bottom end face of the upper exhaust channel sand core is provided with a second square upper recess that matches the second square positioning protrusion. The upper exhaust channel sand core is positioned on the lower exhaust channel sand core through the convex-concave fit between the second square upper recess and the second square positioning protrusion.

[0012] Furthermore, a first positioning hole is provided in the middle region of the lower water jacket sand core, and two first annular positioning bosses are provided at intervals on the rear end face of the lower water jacket sand core. The middle water jacket sand core includes a columnar body vertically arranged on its front bottom surface and two horizontal positioning blocks arranged on its rear end face. A first positioning post adapted to the first positioning hole is provided on the bottom end face of the columnar body, and a second positioning hole adapted to the first annular positioning boss is provided on the bottom end face of the two horizontal positioning blocks respectively. The middle water jacket sand core is positioned on the lower water jacket sand core by the concave-convex fit between the first positioning post and the first positioning hole and the concave-convex fit between the second positioning hole and the first annular positioning boss.

[0013] Furthermore, two third positioning holes are respectively provided on the lower water jacket sand core on both sides of the first positioning hole, and a fourth positioning hole is respectively provided on the top end face of the rear two ends of the lower water jacket sand core. Two vertical columnar bodies are spaced apart on the bottom surface of the front end of the upper water jacket sand core. A second positioning post adapted to the third positioning hole is provided on the bottom end face of each vertical columnar body. Two second annular positioning bosses adapted to the fourth positioning hole are respectively provided on the bottom surface of the rear two ends of the upper water jacket sand core. The upper water jacket sand core is positioned on the lower water jacket sand core by the concave-convex fit between the second positioning post and the third positioning hole and the concave-convex fit between the second annular positioning boss and the fourth positioning hole.

[0014] Furthermore, two positioning grooves are provided at intervals on the rear side wall of the upper water jacket sand core, and the rear end of the horizontal positioning block extends and inserts into the corresponding positioning groove. The lower water jacket sand core and the upper water jacket sand core are closed together and the middle water jacket sand core is clamped and limited between the two.

[0015] Furthermore, the bottom of the upper water jacket sand core is provided with a third-shaped upper concave part, and the top of the upper exhaust channel sand core is provided with a square positioning boss. The upper water jacket sand core is positioned on the upper exhaust channel sand core through the concave-convex cooperation between the third-shaped upper concave part and the square positioning boss.

[0016] A cylinder head, wherein the inner cavity structure of the cylinder head is cast from the cylinder head sand core structure.

[0017] An engine equipped with the aforementioned cylinder head.

[0018] Compared with the prior art, the present invention has the following advantages: 1. The base sand core is equipped with positioning structures for the lower exhaust channel core and the lower water jacket core to ensure accurate positioning of the base; 2. A square positioning structure is designed between the upper and lower exhaust channels, and the positioning stability of the sand core is improved by pressure matching on the top surface; 3. The front ends of the lower water jacket sand core, the middle water jacket sand core, and the upper water jacket sand core adopt a guided positioning structure. The rear ends of the lower water jacket sand core and the upper water jacket sand core surround and position the rear end of the middle water jacket sand core to form a triangular positioning structure, so as to prevent the sand core from floating or fluctuating during the aluminum molten filling process. 4. The upper exhaust channel core is positioned by the square positioning block at its top engaging with the upper water jacket sand core, ensuring the overall sand core is interlocked and stable; 5. Set the positioning and fitting clearance for each sand core to retain sufficient tolerance space and reduce the risk of sand core breakage. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 This is a partial schematic diagram of the present invention.

[0021] Figure 3 This is a schematic diagram of the base sand core of the present invention.

[0022] Figure 4 This is a schematic diagram of the exhaust duct sand core of the present invention viewed from below.

[0023] Figure 5 This is a top view of the exhaust duct sand core of the present invention.

[0024] Figure 6 This is a schematic diagram of the exhaust channel sand core of the present invention viewed from below.

[0025] Figure 7 This is a top view of the exhaust channel sand core of the present invention.

[0026] Figure 8This is a schematic diagram of the top surface structure of the lower water jacket sand core of the present invention.

[0027] Figure 9 This is a schematic diagram of the bottom structure of the lower water jacket sand core of the present invention.

[0028] Figure 10 This is a schematic diagram of the water jacket structure of the present invention.

[0029] Figure 11 This is a schematic diagram of the water jacket of the present invention viewed from below.

[0030] Figure 12 This is a schematic diagram of the bottom structure of the upper water jacket of the present invention.

[0031] Figure 13 This is a schematic diagram of the bottom positioning structure of the upper water jacket of the present invention.

[0032] Figure 14 This is a vertical cross-sectional view of the rear ends of the lower water jacket, middle water jacket, and upper water jacket of the present invention.

[0033] In the picture, 1. Base sand core; 1.1. Lower water jacket sand core positioning groove; 1.2. Lower water jacket positioning boss; 1.3. First square positioning protrusion; 2. Water jacket sand core; 2.1. First positioning hole; 2.2. First annular positioning boss; 2.3. Third positioning hole; 2.4. Fourth positioning hole; 3. Lower exhaust channel sand core; 3.1 First square upper recess; 3.2 Second square positioning protrusion; 4. Medium-water jacket sand core; 4.1 Columnar body; 4.11. First positioning column; 4.2. Horizontal positioning block; 4.21. Second positioning hole; 5. Upper exhaust channel sand core; 5.1. Second square upper recess; 5.2. Square positioning boss; 6. Upper water jacket sand core; 6.1 Vertical columnar body; 6.2 Second positioning column; 6.3 Second annular positioning boss; 6.4 Positioning groove; 6.5 Third shaped upper concave part. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, 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 effort are within the scope of protection of the present invention.

[0035] The following examples are combined Figures 1-14 The present invention will be described in detail below.

[0036] Example 1: A cylinder head sand core structure, see Figure 1 and Figure 2 As shown, the system includes a base sand core 1 and an exhaust-side sand core. The exhaust-side sand core comprises, from bottom to top, a lower water jacket sand core 2, a lower exhaust channel sand core 3, a middle water jacket sand core 4, an upper exhaust channel sand core 5, and an upper water jacket sand core 6, all sequentially mounted on the base sand core 1. The lower water jacket sand core 2 and the lower exhaust channel sand core 3 are respectively positioned and engaged with the base sand core 1 through their respective concave-convex positioning structures. The upper exhaust channel sand core 5 is positioned and engaged with the lower exhaust channel sand core 3 through its corresponding concave-convex positioning structure. The lower water jacket sand core 2, the middle water jacket sand core 4, and the upper water jacket sand core 6 are mutually fixed through a front-end positioning structure and a rear-end positioning structure. The upper exhaust channel sand core 5 is fixedly connected to the upper water jacket sand core 6 through an interference fit using the concave-convex positioning structure.

[0037] In the positioning structure of each sand core, there is an assembly gap between the mating protrusions and recesses, see... Figure 3 As shown, the base sand core 1 has a lower water jacket sand core positioning groove 1.1. The peripheral sidewalls of the lower water jacket sand core positioning groove 1.1 form a limiting cavity that is U-shaped when viewed from above. Multiple lower water jacket positioning protrusions 1.2 are provided at intervals in the middle area of ​​the bottom of the limiting cavity. The bottom of the lower water jacket sand core 2 has a positioning recess that matches the multiple lower water jacket positioning protrusions 1.2. The bottom of the lower water jacket sand core 2 is fitted into the limiting cavity, and the multiple lower water jacket positioning protrusions 1.2 extend into the corresponding positioning recesses.

[0038] The positioning gap between the lower water jacket sand core positioning groove 1.1 and the bottom of the lower water jacket sand core is designed to be 0.3mm to ensure sufficient movement clearance for the lower water jacket sand core. The multiple lower water jacket positioning protrusions 1.2 are not identical in shape and size; their shape, size, and distribution match the corresponding positioning recesses on the bottom of the lower water jacket, facilitating the insertion of the bottom of the lower water jacket sand core into the limiting cavity of the lower water jacket sand core positioning groove 1.1 on the base sand core 1. The multiple lower water jacket positioning protrusions 1.2 extend into their corresponding positioning recesses. The lower water jacket sand core is then fitted and fixed onto the base sand core.

[0039] A first square positioning protrusion 1.3 is provided on the top end face of the rear side of the positioning groove 1.1 of the lower water jacket sand core on the base sand core 1. Figure 4 As shown, the bottom end face of the lower exhaust channel sand core 3 is provided with a first square upper recess 3.1 that is adapted to the first square positioning protrusion 1.3. The lower exhaust channel sand core 3 is positioned on the base sand core 1 through the concave-convex cooperation between the first square upper recess 3.1 and the first square positioning protrusion 1.3.

[0040] The positioning gap between the first square positioning protrusion 1.3 and the first square upper recess 3.1 of the lower exhaust channel sand core 3 is set to 0.1mm, which ensures accurate positioning of the lower exhaust channel sand core while ensuring sufficient movement clearance of the lower exhaust channel sand core and ensuring tolerance margin.

[0041] See Figure 5 As shown, a second square positioning protrusion 3.2 is provided on the top end face of the lower exhaust channel sand core 3. Figure 6 The bottom end face of the upper exhaust channel sand core 5 is provided with a second square upper recess 5.1 that is adapted to the second square positioning protrusion 3.2. The upper exhaust channel sand core 5 is positioned on the lower exhaust channel sand core 3 through the convex-concave fit between the second square upper recess 5.1 and the second square positioning protrusion 3.2.

[0042] See Figure 8 and Figure 9 As shown, the lower water jacket sand core 2 has a first positioning hole 2.1 in the middle region. The lower water jacket sand core 2 has two first annular positioning bosses 2.2 spaced apart on its rear end face. The middle water jacket sand core 4 includes a columnar body 4.1 vertically arranged on its front bottom surface and two horizontal positioning blocks 4.2 arranged on its rear end face. The bottom end face of the columnar body 4.1 has a first positioning post 4.11 adapted to the first positioning hole 2.1. The bottom end faces of the two horizontal positioning blocks 4.2 are respectively provided with second positioning holes 4.21 adapted to the first annular positioning bosses 2.2. The middle water jacket sand core 4 is positioned on the lower water jacket sand core 2 through the concave-convex fit between the first positioning post 4.11 and the first positioning hole 2.1, and the concave-convex fit between the second positioning hole 4.21 and the first annular positioning bosses 2.2.

[0043] The positioning gap between each positioning structure on the lower water jacket sand core 2 is set to 0.3mm to ensure sufficient movement gap for the water jacket core.

[0044] See Figure 10 and Figure 11 As shown, a first positioning post 4.11 with a guiding positioning structure is provided on the bottom end face of the columnar body 4.1 at the front end of the middle water jacket sand core 4. The depth of the first positioning post 4.11 is designed to be 10mm to ensure accurate guidance and effective fixation, preventing the sand core from floating. Two horizontal positioning blocks 4.2 are provided at the rear end of the middle water jacket sand core 4. The vertical cross-sections of the horizontal positioning blocks 4.2, the lower water jacket sand core 2, and the upper water jacket sand core 6 after positioning can be enclosed to form a circle. The positioning gap is designed to be 0.3mm to ensure sufficient movement clearance for the middle water jacket sand core. The front end of the horizontal positioning block 4.2 is designed as a short vertical section to ensure the fitting clearance between the upper water jacket sand core, the middle water jacket sand core, and the lower water jacket sand core, preventing sand core interference. Two third positioning holes 2.3 are respectively provided on the lower water jacket sand core 2 on both sides of the first positioning hole 2.1. A fourth positioning hole 2.4 is respectively provided on the top end face of the rear two ends of the lower water jacket sand core 2. Two vertical columnar bodies 6.1 are spaced apart on the bottom surface of the front end of the upper water jacket sand core 6. A second positioning post 6.2 adapted to the third positioning hole 2.3 is provided on the bottom end face of each vertical columnar body 6.2. Two second annular positioning bosses 6.3 adapted to the fourth positioning hole 2.4 are respectively provided on the bottom surface of the rear two ends of the upper water jacket sand core 6. The upper water jacket sand core 6 is positioned on the lower water jacket sand core 2 through the concave and convex cooperation between the second positioning post 6.2 and the third positioning hole 2.3 and the concave and convex cooperation between the second annular positioning bosses 6.3 and the fourth positioning hole 2.4.

[0045] See Figure 12 and Figure 13 As shown, two vertical columnar bodies 6.1 are spaced apart on the bottom front end of the upper water jacket sand core 6. A second positioning post 6.2 adapted to the third positioning hole 2.3 is provided on the bottom end face of the vertical columnar body 6.1. The depth of the second positioning post 6.2 is designed to be 10mm to ensure accurate guidance and effective fixation to prevent the sand core from floating. The positioning gap is designed to be 0.3mm.

[0046] Two positioning grooves 6.4 are also provided at intervals on the rear side wall of the upper water jacket sand core 6. The rear end of the horizontal positioning block 4.2 extends and is inserted into the corresponding positioning groove 6.4. The lower water jacket sand core 2 and the upper water jacket sand core 6 are closed together and the middle water jacket sand core 4 is clamped and limited between the two.

[0047] See Figure 14 As shown, the shapes of the two positioning grooves 6.4 on the rear side wall of the upper water jacket sand core 6 are adapted to the shape of the rear extension insertion portion of the horizontal positioning block 4.2. The lower water jacket sand core 2 on each side closes up and down with the upper water jacket sand core 6, clamping and limiting the middle water jacket sand core 4.2 between them. The rear vertical cross-sections of the lower water jacket sand core, the middle water jacket sand core, and the upper water jacket sand core form a circle.

[0048] The bottom of the upper water jacket sand core 6 is also provided with a third-shaped upper concave part 6.5, see Figure 7 As shown, the top of the upper exhaust channel sand core 5 is provided with a square positioning boss 5.2, and the upper water jacket sand core 6 is positioned on the upper exhaust channel sand core 5 through the concave-convex cooperation between the third square upper concave part 6.5 and the square positioning boss 5.2.

[0049] The square positioning boss 5.2 on the top of the upper exhaust sand core 5 and the third-shaped upper concave part 6.5 at the bottom of the upper water jacket sand core 6 are designed with an interference fit of 0.1mm to ensure tightness and overall stability of the sand core.

[0050] The usage method is as follows: (1) The base sand core and the lower exhaust channel sand core are positioned in a square shape, with a gap of 0.1mm, to ensure the positioning accuracy of the key dimensions of the air passage; (2) The lower water jacket sand core, the middle water jacket sand core and the upper water jacket sand core are triangularly positioned at the end, which can not only ensure interlocking and avoid the sand core being cheap, but also leave a 0.3mm fault tolerance space to avoid the thin-walled water jacket structure from breaking during the casting process. (3) A guide positioning structure is designed on the lower water jacket core to ensure that the middle water jacket sand core and the upper water jacket sand core are fixed laterally, so as to avoid the water jacket core floating during the aluminum liquid filling process and causing the sand core to shift. (4) The upper exhaust channel sand core and the upper water jacket sand core adopt an integral planar interference fit in the vertical direction and an upper and lower pressing structure to ensure the stable combination of the overall sand core and tight fit, so as to avoid leakage and overflow during the filling process of aluminum liquid casting.

[0051] During assembly, the sand cores are assembled in the following order: base sand core - lower water jacket sand core - lower exhaust channel sand core - middle water jacket sand core - upper exhaust channel sand core - upper water jacket sand core. Finally, glue is applied to fix the sand cores. This ensures that the positioning accuracy of the key positions of the air channels is controlled within 0.1mm, and also leaves a 0.3mm clearance for the water jacket cores to prevent them from floating and breaking during the casting process.

[0052] Example 3: The present invention also provides a cylinder head, wherein the inner cavity structure of the cylinder head is cast from the cylinder head sand core structure.

[0053] Example 4: The present invention also provides an engine equipped with the aforementioned cylinder head.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cylinder head sand core structure, characterized in that, The system includes a base sand core (1) and an exhaust side sand core. The exhaust side sand core includes a lower water jacket sand core (2), a lower exhaust channel sand core (3), a middle water jacket sand core (4), an upper exhaust channel sand core (5), and an upper water jacket sand core (6) which are sequentially assembled on the base sand core (1) from bottom to top. The lower water jacket sand core (2) and the lower exhaust channel sand core (3) are respectively positioned and engaged with the base sand core (1) through their respective concave and convex positioning structures. The upper exhaust channel sand core (5) is positioned and engaged with the lower exhaust channel sand core (3) through its corresponding concave and convex positioning structure. The lower water jacket sand core (2), the middle water jacket sand core (4), and the upper water jacket sand core (6) are mutually fixed through a front-end positioning structure and a rear-end positioning structure. The upper exhaust channel sand core (5) is fixedly connected to the upper water jacket sand core (6) through an interference fit of the concave and convex positioning structure.

2. The cylinder head sand core structure according to claim 1, characterized in that, In the positioning structure of each sand core, there is an assembly gap between the matching protrusions and recesses. The base sand core (1) is provided with a lower water jacket sand core positioning groove (1.1). The peripheral sidewall of the lower water jacket sand core positioning groove (1.1) forms a limiting cavity that is "U" shaped when viewed from above. Multiple lower water jacket positioning protrusions (1.2) are provided at intervals in the middle area at the bottom of the limiting cavity. The bottom of the lower water jacket sand core (2) is provided with a positioning recess that matches the multiple lower water jacket positioning protrusions (1.2). The bottom of the lower water jacket sand core (2) is fitted into the limiting cavity, and the multiple lower water jacket positioning protrusions (1.2) extend into the corresponding positioning recess.

3. The cylinder head sand core structure according to claim 2, characterized in that, The base sand core (1) has a first square positioning protrusion (1.3) on the top end face of the lower water jacket sand core positioning groove (1.1) as shown in Figure 11. The bottom end face of the lower exhaust channel sand core (3) has a first square upper recess (3.1) that matches the first square positioning protrusion (1.3). The lower exhaust channel sand core (3) is positioned on the base sand core (1) through the concave-convex cooperation between the first square upper recess (3.1) and the first square positioning protrusion (1.3).

4. The cylinder head sand core structure according to claim 2, characterized in that, As shown in Figure 12, a second square positioning protrusion (3.2) is provided on the top end face of the lower exhaust channel sand core (3). As shown in Figure 13, a second square upper recess (5.1) that matches the second square positioning protrusion (3.2) is provided on the bottom end face of the upper exhaust channel sand core (5). The upper exhaust channel sand core (5) is positioned on the lower exhaust channel sand core (3) through the concave-convex cooperation between the second square upper recess (5.1) and the second square positioning protrusion (3.2).

5. The cylinder head sand core structure according to claim 2, characterized in that, The lower water jacket sand core (2) has a first positioning hole (2.1) in the middle area. The lower water jacket sand core (2) has two first annular positioning bosses (2.2) spaced apart on the rear end face. The middle water jacket sand core (4) includes a columnar body (4.1) vertically arranged on its front end bottom surface and two horizontal positioning blocks (4.2) arranged on its rear end end face. The bottom end face of the columnar body (4.1) has a first positioning post (4.11) adapted to the first positioning hole (2.1). The bottom end faces of the two horizontal positioning blocks (4.2) are respectively provided with second positioning holes (4.21) adapted to the first annular positioning bosses (2.2). The middle water jacket sand core (4) is positioned on the lower water jacket sand core (2) through the concave-convex fit between the first positioning post (4.11) and the first positioning hole (2.1) and the concave-convex fit between the second positioning hole (4.21) and the first annular positioning bosses (2.2).

6. The cylinder head sand core structure according to claim 5, characterized in that, Two third positioning holes (2.3) are respectively provided on the lower water jacket sand core (2) on both sides of the first positioning hole (2.1). A fourth positioning hole (2.4) is respectively provided on the top end face of the rear two ends of the lower water jacket sand core (2). Two vertical columnar bodies (6.1) are spaced apart on the bottom surface of the front end of the upper water jacket sand core (6). A second positioning post (6.2) adapted to the third positioning hole (2.3) is provided on the bottom end face of each vertical columnar body (6.1). Two second annular positioning bosses (6.3) adapted to the fourth positioning hole (2.4) are respectively provided on the bottom surface of the rear two ends of the upper water jacket sand core (6). The upper water jacket sand core (6) is positioned on the lower water jacket sand core (2) through the concave-convex cooperation of the second positioning post (6.2) and the third positioning hole (2.3) and the concave-convex cooperation of the second annular positioning boss (6.3) and the fourth positioning hole (2.4).

7. The cylinder head sand core structure according to claim 6, characterized in that, Two positioning grooves (6.4) are provided at intervals on the rear side wall of the upper water jacket sand core (6). The rear end of the horizontal positioning block (4.2) extends and inserts into the corresponding positioning groove (6.4). The lower water jacket sand core (2) and the upper water jacket sand core (6) are closed together and the middle water jacket sand core (4) is clamped and limited between the two.

8. The cylinder head sand core structure according to claim 2, characterized in that, The bottom of the upper water jacket sand core (6) is provided with a third-shaped upper recess (6.5), and the top of the upper exhaust channel sand core (5) is provided with a square positioning boss (5.2). The upper water jacket sand core (6) is positioned on the upper exhaust channel sand core (5) through the concave-convex cooperation between the third-shaped upper recess (6.5) and the square positioning boss (5.2).

9. A cylinder head, characterized in that, The internal cavity structure of the cylinder head is cast from the cylinder head sand core structure as described in any one of claims 1 to 8.

10. An engine, characterized in that, It is equipped with the cylinder head as described in claim 9.

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