Cylinder head test core box and engine test system

Abstract

The application provides a cylinder head test core box and an engine test system. The cylinder head test core box is internally provided with a test air channel. The cylinder head test core box comprises a core box main body and a seat ring. The core box main body is provided with an air inlet channel and an air outlet channel which are in communication with the test air channel. The core box main body is provided with a mounting groove which is in communication with the air outlet channel at the air outlet channel. The seat ring is detachably mounted in the mounting groove and is provided with a flow guide channel. In the application, the mounting groove is larger than the existing test core box, and the seat ring is provided with the flow guide channel which actually corresponds to the structure of the air outlet of the cylinder head. Therefore, when the influence of different air outlet structures of the cylinder head on the air inlet performance of the test air channel needs to be tested, different seat rings can be replaced, so that the flow guide channel corresponds to the structure of the air outlet of the required cylinder head. In this way, the test is more convenient, and the test cost is also lower.

Description

Technical Field

[0001] This application relates to the field of engine technology, and in particular to cylinder head test core boxes and engine test systems. Background Technology

[0002] The design of an engine's intake manifold requires prior design completion before testing. After the intake manifold design is finalized, a core box is typically fabricated, and test intake manifolds are installed within this core box to verify its performance. The exhaust ports on the core box must correspond to the intake ports on the cylinder head to fully validate the intake manifold's effectiveness. However, when testing the impact of different cylinder head intake port structures on the test intake manifold's performance, separate core boxes must be fabricated for each test, significantly increasing the complexity and cost of the testing process. Summary of the Invention

[0003] Therefore, it is necessary to provide a cylinder head test core box and engine test system to address the problem that different core boxes need to be made separately when testing different intake port structures of cylinder heads, which leads to complicated test operations and increased test costs.

[0004] According to a first aspect of this application, a cylinder head test core box is provided. The cylinder head test core box has a test air passage inside, and is used in conjunction with testing equipment to detect the intake efficiency of the test air passage. The cylinder head test core box includes:

[0005] The core box body is provided with an air inlet channel and an air outlet channel that are connected to the test air channel; the core box body is provided with a mounting groove at the air outlet channel that is connected to the air outlet channel.

[0006] The seat ring is detachably installed in the mounting groove, and the seat ring has a flow guiding channel that is connected to the downstream side of the air outlet channel.

[0007] In one embodiment, the core box body is further recessed with a docking groove for adapting and connecting the test equipment;

[0008] The mounting groove is recessed into the bottom wall of the docking groove.

[0009] In one embodiment, a fixing hole communicating with the mounting groove is provided on the side wall of the core box body;

[0010] The cylinder head test core box also includes a fastener adapted to the fixing hole. The fastener passes through the fixing hole into the mounting groove to fix the seat ring in the mounting groove.

[0011] In one embodiment, the sidewall of the flow guiding channel includes a plurality of flow guiding portions spaced apart along the circumferential direction of the flow guiding channel; the inner sidewall of the flow guiding portion extends obliquely outward along the radial direction of the flow guiding channel.

[0012] The deflection angle of the guide portion near the center of the docking groove is 'a', and the deflection angle of the guide portion near the side wall of the docking groove is 'b', where a > b.

[0013] In one embodiment, a positioning portion is provided on the outer side of the seat ring, and the positioning portion extends in a straight line;

[0014] The sidewall of the mounting groove includes a positioning wall surface corresponding to the positioning part. The positioning wall surface is used to abut against the positioning part when the seat ring is installed, so that the seat ring is installed in the mounting groove in a preset posture.

[0015] In one embodiment, the cylinder head test core box is provided with two air outlet channels, and the bottom wall of the docking groove is recessed with two mounting grooves that correspond one-to-one with the air outlet channels;

[0016] The sidewalls of the two mounting slots overlap each other, and a connecting opening is formed at the overlap of the sidewalls of the two mounting slots, the connecting opening connecting the two mounting slots. The positioning wall is formed on the sidewall with the connecting opening, so that the two seat rings can be positioned one-to-one in the two mounting slots.

[0017] In one embodiment, the core box body is further provided with a valve mounting hole, which is used to connect the test air passage to the outside; the axis of the valve mounting hole is collinear with the axis of the air outlet passage.

[0018] The cylinder head test core box also includes a valve corresponding to the valve mounting hole. The valve stem is adjustablely installed in the valve mounting hole along the axial direction of the valve mounting hole, and the end of the valve stem away from the valve mounting hole passes through the air outlet and the flow guide channel in sequence, so that the valve head extends out of the core box body.

[0019] In one embodiment, the cylinder head test core box further includes a valve guide corresponding to the valve mounting hole, and the valve guide is detachably installed in the valve mounting hole;

[0020] The valve stem is adjustablely installed inside the valve guide along the extension direction of the valve guide.

[0021] In one embodiment, the valve guide has a flange extending radially outward at one end near the outer side of the core box body. The flange is used to abut against the periphery of the valve mounting hole opening when the valve guide is installed in the valve mounting hole.

[0022] According to a second aspect of this application, an engine testing system is also provided, comprising a cylinder head test core box as described above, wherein the cylinder head test core box has a test air passage inside, and the cylinder head test core box is used to cooperate with testing equipment to detect the intake efficiency of the test air passage, the cylinder head test core box comprising:

[0023] The core box body is provided with an air inlet channel and an air outlet channel that are connected to the test air channel; the core box body is provided with a mounting groove at the air outlet channel that is connected to the air outlet channel.

[0024] The seat ring is detachably installed in the mounting groove, and the seat ring has a flow guiding channel that is connected to the downstream side of the air outlet channel.

[0025] In this application's technical solution, a test air passage is provided within the cylinder head test core box, and the cylinder head test core box can cooperate with test equipment, thus enabling the test equipment to test the intake efficiency of the test air passage. The cylinder head test core box is provided with an intake channel and an exhaust channel communicating with the test air passage, and a seat ring is detachably installed in a mounting groove communicating with the exhaust channel. The test equipment needs to supply air to the intake channel and receive the gas output through the exhaust channel via the seat ring, thereby testing the intake performance of the test air passage.

[0026] The structure at the cylinder head's exhaust port is typically located around the mounting groove and integrally formed with the core box body, making it impossible to change. In this application, however, the mounting groove is larger than existing test core boxes, and the mounting ring has a flow guide channel that corresponds to the structure at the cylinder head's exhaust port. Therefore, when testing the effect of different cylinder head exhaust port structures on the intake performance of the test air passage, different mounting rings can be used, allowing the flow guide channel to correspond to the desired cylinder head exhaust port structure. This makes testing more convenient and reduces testing costs. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an embodiment of the cylinder head test core box proposed in this application;

[0028] Figure 2 for Figure 1 Exploded view of the test core box for the middle cylinder head;

[0029] Figure 3 for Figure 1 Top view of the test core box for the middle cylinder head;

[0030] Figure 4 for Figure 3 Schematic diagram of the cross section at point AA;

[0031] Figure 5 for Figure 1 A schematic diagram of the middle seat ring.

[0032] Explanation of icon numbers:

[0033]

[0034] Detailed Implementation

[0035] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0036] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0039] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0040] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0041] The design of an engine's intake manifold requires prior design completion before testing. After the intake manifold design is finalized, a core box is typically fabricated, and test intake manifolds are installed within this core box to verify its performance. The exhaust ports on the core box must correspond to the intake ports on the cylinder head to fully validate the intake manifold's effectiveness. However, when testing the impact of different cylinder head intake port structures on the test intake manifold's performance, separate core boxes must be fabricated for each test, significantly increasing the complexity and cost of the testing process.

[0042] The inventors of this application discovered through research that different intake port structures of the cylinder head have a certain impact on the intake performance of the test air passage. Therefore, when designing the cylinder head intake passage, it is also necessary to test the impact of different intake port structures of the cylinder head on the intake performance of the test air passage. The cylinder head intake port is actually integrally set with the cylinder head body, which means that the intake port structure of the cylinder head on the existing cylinder head test core box is integrally set with the core box body, making replacement impossible.

[0043] Through further research, the inventors of this application discovered that the seat ring on the cylinder head test core box is replaceable, and the air intake structure of the cylinder head is located on the periphery of the seat ring. Therefore, the air intake structure of the cylinder head can be modified to be integrally formed with the seat ring, so that the air intake structure of the cylinder head can be replaced by replacing the seat ring. This makes the test operation simpler and the test cost lower.

[0044] In view of this, this application proposes a cylinder head test core box, which aims to solve the problem that when testing different intake port structures of cylinder heads, it is necessary to manufacture corresponding core boxes separately, which leads to complicated test operations and increased test costs. Figures 1 to 5 This is a schematic diagram of the cylinder head test core box proposed in this application.

[0045] Please see Figures 1 to 3 The cylinder head test core box 100 proposed in this application has a test air passage 200 inside. The cylinder head test core box 100 is used to cooperate with test equipment to test the intake efficiency of the test air passage 200. The cylinder head test core box 100 includes a core box body 1 and a seat ring 2. The core box body 1 has an intake channel 11 and an exhaust channel 12 that communicate with the test air passage 200. The core box body 1 has a mounting groove 13 at the exhaust channel 12 that communicates with the exhaust channel 12. The seat ring 2 is detachably installed in the mounting groove 13. The seat ring 2 has a guide channel 21 that communicates with the downstream side of the exhaust channel 12.

[0046] In the technical solution of this application, a test air passage 200 is provided inside the cylinder head test core box 100, and the cylinder head test core box 100 can cooperate with test equipment, so that the test equipment can test the intake efficiency of the test air passage 200. The cylinder head test core box 100 is provided with an intake channel 11 and an exhaust channel 12 that communicate with the test air passage 200, and the seat ring 2 is detachably installed in the mounting groove 13 that communicates with the exhaust channel 12. The test equipment can supply air to the intake channel 11 and receive the gas output through the exhaust channel 12 via the seat ring 2, thereby testing the intake performance of the test air passage 200.

[0047] The structure at the cylinder head's exhaust port is typically located around the mounting groove 13 and integrally formed with the core box body 1, making it impossible to change the structure at the cylinder head's exhaust port. However, in this application, the mounting groove 13 is larger than existing test core boxes, and the seat ring 2 is provided with a flow guide channel 21. The flow guide channel 21 corresponds to the structure at the cylinder head's exhaust port. Therefore, when testing the effect of different cylinder head exhaust port structures on the intake performance of the test air passage 200, different seat rings 2 can be replaced, allowing the flow guide channel 21 to correspond to the desired cylinder head exhaust port structure. This makes the test more convenient and reduces testing costs.

[0048] Please see Figure 1 and Figure 3In some embodiments, the core box body 1 is further recessed with a docking groove 14 for adapting and connecting test equipment. The mounting groove 13 is recessed in the bottom wall of the docking groove 14.

[0049] In actual use, the cylinder head test core box 100 needs to be connected and fitted with the test equipment along the axial direction of the air outlet channel. The test equipment will inflate the test air passage 200 through the air inlet channel 11 and then allow air to enter through the air outlet channel 12 to test the air intake performance of the test air passage 200. Therefore, the test equipment needs to be connected to the air outlet channel 12 to receive the air entering through the test air passage 200. Therefore, the recessed mating groove 14 of this application is located at the opening of the air outlet channel 12, and the mounting groove 13 is recessed on the bottom wall of the mating groove 14. When the core box body 1 is adapted to connect with the test equipment, the test equipment is also connected to the air outlet channel 12.

[0050] In some embodiments, a fixing hole 15 communicating with the mounting groove 13 is provided on the side wall of the core box body 1. The cylinder head test core box 100 also includes a fixing member 4 adapted to the fixing hole 15. The fixing member 4 passes through the fixing hole 15 into the mounting groove 13 to fix the seat ring 2 in the mounting groove 13.

[0051] When the seat ring 2 is installed in the mounting groove 13, it may move within the mounting groove 13. Therefore, this application also provides a fixing member 4. The fixing member 4 can extend into the mounting groove 13 from the side wall of the mounting groove 13 through the fixing hole 15 and abut against the seat ring 2 in the mounting groove 13, thereby fixing the seat ring 2 in the mounting groove 13. It should be noted that there are many ways for the fixing member 4 to cooperate with the fixing hole 15. The fixing member 4 and the fixing hole 15 can be directly connected by threads to tighten the seat ring 2. The fixing member 4 can also be installed in the fixing hole 15 by snap-fit ​​to tighten the seat ring 2.

[0052] Please refer to the figure. Figures 3 to 5 In some embodiments, the sidewall of the flow channel 21 includes a plurality of flow guiding portions 211 spaced apart along the circumferential direction of the flow channel 21. The inner sidewall of the flow guiding portion 211 extends obliquely outward along the radial direction of the flow channel 21. The oblique angle of the flow guiding portion 211 near the center of the docking groove 14 is α, and the oblique angle of the flow guiding portion 211 near the sidewall of the docking groove 14 is β, where α > β.

[0053] The flow guide channel 21 actually corresponds to the structure at the cylinder head's exhaust port. Therefore, when it is necessary to test the effect of different cylinder head exhaust port structures on the intake performance of the test air passage 200, different seat rings 2 can be replaced to make the flow guide channel 21 correspond to the required cylinder head exhaust port structure. In fact, the flow guide channel 21 is provided with multiple flow guide sections 211 to achieve the flow guide effect. The inner sidewalls of the multiple flow guide sections 211 extend outward at an angle along the radial direction of the flow guide channel 21, thereby forming an outwardly expanding structure for flow guidance.

[0054] In practical applications of cylinder heads, the outward expansion angle of the intake port is not necessarily better the larger it is. Specifically, the outward expansion angle of the portion of the intake port closest to the cylinder wall should not be too large. If the outward expansion angle of this portion is too large, part of the guide section 211 may extend above the cylinder sidewall, creating an intake dead zone. In practical applications, airflow may stagnate in this dead zone, affecting intake efficiency.

[0055] In the actual application of the cylinder head test core box 100, the size of the mating groove 14 is set to correspond to the cross-section of the cylinder, and the relative positional relationship between the mounting groove 13 and the mating groove 14 also corresponds to the relative positional relationship between the cylinder head air inlet and the cylinder, thereby making the test effect of the cylinder head test core box 100 more realistic. Therefore, in this embodiment, the deflection angle of the guide portion 211 near the center of the mating groove 14 is greater than the deflection angle of the guide portion 211 near the side wall of the mating groove 14, thus avoiding the formation of dead zones. The guide portion 211 at the center of the mating groove 14 does not form dead zones and can be deflected at a larger angle, resulting in better guide effect.

[0056] In some embodiments, a positioning portion 22 is provided on the outer side of the seat ring 2, and the positioning portion 22 extends in a straight line. The side wall of the mounting groove 13 includes a positioning wall surface corresponding to the positioning portion 22, which is used to abut against the positioning portion 22 when the seat ring 2 is installed, so that the seat ring 2 is installed in the mounting groove 13 in a preset posture.

[0057] In practical applications, the seat ring 2 is generally circular, which requires the seat ring 2 to be fixed in position during installation to ensure that the installation position of the guide portion 211 corresponds to the tilt angle. Therefore, in this embodiment, the outer side of the seat ring 2 is provided with a linearly extending positioning portion 22, and the side wall of the mounting groove 13 includes a positioning wall surface corresponding to the positioning portion 22. This allows the positioning portion 22 to abut against the positioning wall surface during installation, thus restricting the movement of the seat ring 2 and ensuring that the seat ring 2 is fixedly installed in the mounting groove 13 in a preset posture, thereby making the test of the cylinder head test core box 100 more accurate.

[0058] Please see Figure 1 , Figure 3 and Figure 4In some embodiments, the cylinder head test core box 100 is provided with two air outlet channels 12, and the bottom wall of the mating groove 14 is recessed with two mounting grooves 13 corresponding to the air outlet channels 12. The side walls of the two mounting grooves 13 overlap each other, and a connecting opening is formed at the overlap of the side walls of the two mounting grooves 13, the connecting opening connecting the two mounting grooves 13. The positioning wall is formed on the side wall with the connecting opening, so that the two seat rings 2 can be positioned one-to-one in the two mounting grooves 13.

[0059] In this embodiment, the two mounting slots 13 overlap each other, and a connecting opening is provided at the overlap. This conforms to the actual setting of the cylinder head's air intake, making the air intake efficiency of the cylinder head test core box 100 more consistent with the actual air intake efficiency of the air intake channel. Furthermore, this arrangement allows the positioning parts 22 of the two seat rings 2 to abut against each other through the connecting opening during installation, thus securing them together. The overlap of the two mounting slots 13 and the abutment of the two positioning parts 22 result in a smaller space occupied by the two mounting slots 13, leading to a higher degree of consistency between the air intake efficiency and the actual effect.

[0060] Please see Figure 2 and Figure 4 In some embodiments, the core box body 1 is further provided with a valve mounting hole 16, which is used to connect the test air passage 200 to the outside. The axis of the valve mounting hole 16 is collinear with the axis of the air outlet passage 12. The cylinder head test core box 100 also includes a valve corresponding to the valve mounting hole 16. The valve stem is adjustablely installed in the valve mounting hole 16 along the axial direction of the valve mounting hole 16, and the end of the valve stem away from the valve mounting hole 16 passes through the air outlet passage 12 and the guide channel 21 in sequence, so that the valve head extends out of the core box body 1.

[0061] The cylinder head test core box 100 is also equipped with valves. The valve stem is adjustablely installed within the valve mounting hole 16 along its axial direction, allowing for adjustment of the valve opening. Therefore, the cylinder head test core box 100 proposed in this application can test the intake efficiency of the cylinder head intake manifold under different valve openings, and then statistically calculate the intake efficiency of the cylinder head intake manifold based on the statistical calculations. Thus, the cylinder head test core box 100 can perform repeated tests by adjusting the valve opening, and the results of multiple tests can be used for calculation, making the test results more accurate.

[0062] In some embodiments, the cylinder head test core box 100 further includes a valve guide 3 corresponding to the valve mounting hole 16, the valve guide 3 being detachably installed in the valve mounting hole 16. The valve stem is adjustablely installed within the valve guide 3 along the extending direction of the valve guide 3.

[0063] In this embodiment, the valve mounting hole 16 is also provided with a valve guide 3. The valve stem passes through the valve guide 3, which ensures that the valve moves in a straight line and prevents it from deflecting, thus ensuring that the test results are not affected. Furthermore, the valve guide 3 is detachably installed in the valve mounting hole 16. When it is necessary to replace a different type of valve, only the corresponding valve guide 3 needs to be replaced, ensuring that the valve and valve guide 3 remain in close contact and guaranteeing the guiding effect of the valve guide 3.

[0064] In some embodiments, a flange 31 is provided at one end of the valve guide 3 near the outer side of the core box body 1, extending radially outward along the valve guide 3. The flange 31 is used to abut against the periphery of the opening of the valve mounting hole 16 when the valve guide 3 is installed in the valve mounting hole 16.

[0065] When the valve guide 3 extends into the valve mounting hole 16, the flange 31 will gradually approach the end of the valve mounting hole 16 located on the outside of the cylinder head test core box 100. Therefore, when the valve guide 3 is installed in the valve mounting hole 16, the flange 31 abuts against the periphery of the opening of the valve mounting hole 16, thereby preventing the air in the intake manifold from escaping to the outside through the valve mounting hole 16, reducing the influence of the valve mounting hole 16 on the intake manifold, and making the experimental results more accurate.

[0066] This application also proposes an engine testing system, including the cylinder head test core box 100 as described in any of the above embodiments. Any engine testing system that includes the cylinder head test core box 100 as described above falls under the category of engine testing systems described in this application.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A cylinder head test core box, characterized in that, The cylinder head test core box has a test air passage inside. The cylinder head test core box is used in conjunction with test equipment to test the intake efficiency of the test air passage. The cylinder head test core box includes: The core box body is provided with an air inlet channel and an air outlet channel that are connected to the test air channel; the core box body is provided with a mounting groove at the air outlet channel that is connected to the air outlet channel. A seat ring is detachably installed in the mounting groove. The seat ring has a flow guiding channel, which is connected to the downstream side of the air outlet channel. The core box body is also recessed with a docking groove for adapting and connecting the test equipment; The mounting groove is recessed into the bottom wall of the docking groove; The outer side of the seat ring is provided with a positioning part, which extends in a straight line; The sidewall of the mounting groove includes a positioning wall surface corresponding to the positioning part. The positioning wall surface is used to abut against the positioning part when the seat ring is installed, so that the seat ring is installed in the mounting groove in a preset posture. The cylinder head test core box is provided with two air outlet channels, and the bottom wall of the docking groove is recessed with two mounting grooves that correspond one-to-one with the air outlet channels; The sidewalls of the two mounting slots overlap each other, and a connecting opening is formed at the overlap of the sidewalls of the two mounting slots. The connecting opening connects the two mounting slots. The positioning wall is formed on the sidewall with the connecting opening so that the two seat rings can be positioned one-to-one in the two mounting slots. The positioning parts of the two seat rings will abut against each other through the connecting opening.

2. The cylinder head test core box according to claim 1, characterized in that, The side wall of the core box body is provided with a fixing hole that communicates with the mounting groove; The cylinder head test core box also includes a fastener adapted to the fixing hole. The fastener passes through the fixing hole into the mounting groove to fix the seat ring in the mounting groove.

3. The cylinder head test core box according to claim 1, characterized in that, The sidewall of the flow guiding channel includes a plurality of flow guiding sections spaced apart along the circumferential direction of the flow guiding channel; the inner sidewall of the flow guiding section extends obliquely outward along the radial direction of the flow guiding channel. The deflection angle of the guide portion near the center of the docking groove is 'a', and the deflection angle of the guide portion near the side wall of the docking groove is 'b', where a > b.

4. The cylinder head test core box according to claim 1, characterized in that, The core box body is also provided with a valve mounting hole, which is used to connect the test air passage to the outside; the axis of the valve mounting hole is collinear with the axis of the air outlet passage. The cylinder head test core box also includes a valve corresponding to the valve mounting hole. The valve stem is adjustablely installed in the valve mounting hole along the axial direction of the valve mounting hole, and the end of the valve stem away from the valve mounting hole passes through the air outlet and the flow guide channel in sequence, so that the valve head extends out of the core box body.

5. The cylinder head test core box according to claim 4, characterized in that, It also includes a valve guide disposed corresponding to the valve mounting hole, the valve guide being detachably installed in the valve mounting hole; The valve stem is adjustablely installed inside the valve guide along the extension direction of the valve guide.

6. The cylinder head test core box according to claim 5, characterized in that, The valve guide has a flange extending radially outward at one end near the outer side of the core box body. The flange is used to abut against the periphery of the valve mounting hole opening when the valve guide is installed in the valve mounting hole.

7. An engine testing system, characterized in that, Includes the cylinder head test core box as described in any one of claims 1 to 6.

Images