A method for simulating engine cylinder head load

Abstract

The present invention provides a method for simulating the load of an engine cylinder head, comprising the following steps: S1, installing a fastening device on the surface of the cylinder head; S2, extending a loading rod through the fastening device into an injection hole or an air passage; S3, simulating the uneven state of thermal load on the intake and exhaust sides through the loading rod; S4, determining the load of the loading rod; S5, converting the loading load into an installation preload; the fastening device is in a rectangular block shape, and the fastening device includes a fastening block and a loading rod, the fastening block is provided with a No. 1 screw hole, a No. 2 screw hole and a matching hole, and the bolts respectively pass through the No. 1 screw hole and the No. 2 screw hole to fix the fastening block on the surface of the cylinder head, and the fastening block is also provided with a matching hole, and the matching hole corresponds to the injection hole or the air passage, and the loading rod is placed in the injection hole or the air passage through the matching hole. The test method of the present invention is simple and easy to install, and can be used to perform component tests in advance to verify such potential fatigue cracking failure forms, or to verify the cylinder head after optimization and improvement.

Description

Technical Field

[0001] The invention belongs to the field of engines, and in particular relates to a method for simulating the load of an engine cylinder head. Background Art

[0002] The existing mechanical component assessment test of the diesel engine cylinder head is mainly a hydraulic fatigue assessment. First, the cylinder head is installed with bolts on the test bench to simulate the preload force of the cylinder head in actual operation. Then, a hydraulic fatigue test device is used to simulate the combustion pressure in the engine cylinder and load the cylinder head. The advantage of this test method is that the preload force and explosion pressure of the cylinder head can be better simulated. The disadvantage is that the effect of thermal load cannot be considered. The connection between the cylinder head injection hole or airway and the water cavity side of the base plate (fire surface) is a common location for fatigue cracking of the cylinder head. Summary of the invention

[0003] In view of this, the present invention aims to propose a method for simulating the load of an engine cylinder head. The test method is simple and easy to install, and can be used to conduct component tests in advance to verify such potential fatigue cracking failure forms, or to verify the optimized and improved cylinder head.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A method for simulating engine cylinder head load, comprising the following steps:

[0006] S1. Install the fastening device to the surface of the cylinder head;

[0007] S2. Extend the loading rod into the oil injection hole or air passage through the fastening device;

[0008] S3, simulating the uneven state of thermal load on the intake and exhaust sides by loading the rod;

[0009] S4, determining the load of the loading rod;

[0010] S5. Convert the loading load into the installation preload;

[0011] Furthermore, the fastening device is in the shape of a rectangular block, and the fastening device includes a fastening block and a loading rod body. The fastening block is provided with a No. 1 screw hole, a No. 2 screw hole and a matching hole. Bolts respectively pass through the No. 1 screw hole and the No. 2 screw hole to fix the fastening block to the surface of the cylinder head. The fastening block also has a matching hole, and the matching hole corresponds to the injection hole or the air duct. The loading rod body passes through the matching hole and is placed in the injection hole or the air duct.

[0012] Furthermore, an internal thread is provided at the opening of the matching hole, and an external thread is provided on the surface of the loading rod body, so as to realize the threaded connection between the loading rod body and the matching hole.

[0013] Furthermore, the loading rod includes a straight rod and a carrier, wherein one side of the bottom of the straight rod is an inclined surface structure, the ratio of the inclined surface length to the diameter of the straight rod is 1:3-1:4; the angle of inclination of the inclined surface and the horizontal plane is 30°-45°; the carrier is installed on the inclined surface of the straight rod.

[0014] Furthermore, in S4, the linear relationship between the loading load and the stress and safety factor of the dangerous parts is found by using the finite element analysis method of linear increase of the load of multiple load parts, and the appropriate loading load is determined.

[0015] Compared with the prior art, the engine cylinder head load simulation method of the present invention has the following advantages:

[0016] (1) The present invention provides a method for simulating the load of an engine cylinder head. The test method is simple and easy to install. It can be used to conduct component tests to verify such potential fatigue cracking failure forms in advance, or to verify the optimized and improved cylinder head. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 A schematic diagram of a fastening device according to an embodiment of the present invention being installed on a cylinder head;

[0019] Figure 2 It is a schematic diagram of the linear relationship between the loading load, the stress of the dangerous part and the safety factor in an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of a stress-strain cloud diagram of a cylinder head under a bolt pre-tightening force according to an embodiment of the present invention;

[0021] Figure 4 It is a schematic diagram of a stress-strain cloud diagram of a cylinder head under bolt preload and temperature load according to an embodiment of the present invention;

[0022] Figure 5 It is a schematic diagram of a stress-strain cloud diagram of a cylinder head under bolt preload, temperature load and burst load according to an embodiment of the present invention;

[0023] Description of reference numerals:

[0024] 1. Fastening device; 12. Fastening block; 13. Loading rod; 131. Straight rod; 132. Carrying body; 133. Inclined surface; 14. No. 2 bolt; 15. Matching hole; 16. Matching hole; 17. No. 1 bolt; 2. Cylinder head; 3. Dangerous point; 4. Injection hole. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0028] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0029] The joint between the cylinder head injection hole or airway and the water cavity side of the base plate (fire surface) is a common location for fatigue cracking of the cylinder head. The stress-strain cloud diagram of the cylinder head under the bolt preload is shown in the figure below. Figure 3 As shown in the figure, the strain and stress at the connection between the airway wall or the injector hole and the base plate (hereinafter referred to as the dangerous point) are not large. When there is a thermal load, the cylinder head fire surface is obviously "protruding" outward. At this time, the dangerous part is mainly tensile stress. The stress-strain cloud diagram under preload and temperature load is as follows Figure 4 As shown in the figure, the stress-strain cloud diagram of the cylinder head under the explosion pressure is as follows: Figure 5 As shown, at this time, the deformation of the base plate is "recovered", and the displacement within the "engine cylinder diameter" range is the largest. At this time, the stress at the dangerous point becomes a compressive stress state again; through the analysis of the stress-strain results of the cylinder head, it can be seen that the tensile stress generated by the cylinder head under the action of the thermal load is the main load for cracking in the dangerous part. If the loading is not considered during the component test, it will be difficult to simulate the actual stress state of the cylinder head.

[0030] Therefore, a method for simulating engine cylinder head load is proposed, comprising the following steps:

[0031] S1. Install the fastening device to the surface of the cylinder head;

[0032] S2. Extend the loading rod into the oil injection hole or air passage through the fastening device;

[0033] S3, simulating the uneven state of thermal load on the intake and exhaust sides by loading the rod;

[0034] S4. Determine the load on the loading rod; use the finite element analysis method of linear increase of multiple load parts to find the linear relationship between the loading load and the stress and safety factor of the dangerous parts, and determine the appropriate loading load.

[0035] S5. Convert the loading load into installation preload.

[0036] Preferably, Figure 1 As shown, the fastening device is in the shape of a rectangular block, and the fastening device includes a fastening block and a loading rod body. The fastening block is provided with a No. 1 screw hole, a No. 2 screw hole and a matching hole. Bolts respectively pass through the No. 1 screw hole and the No. 2 screw hole to fix the fastening block to the surface of the cylinder head. The fastening block also has a matching hole, and the matching hole corresponds to the injection hole or the air duct. The loading rod body passes through the matching hole and is placed in the injection hole or the air duct.

[0037] Preferably, an internal thread is provided at the opening of the matching hole, and an external thread is provided on the surface of the loading rod body, so as to realize a threaded connection between the loading rod body and the matching hole.

[0038] Preferably, the loading rod includes a straight rod and a carrier, wherein one side of the bottom of the straight rod is an inclined structure, the ratio of the inclined length to the diameter of the straight rod is 1:3-1:4; the angle of inclination of the inclined surface and the horizontal plane is 30°-45°; the carrier is installed on the inclined surface of the straight rod.

[0039] Preferably, the force on the intake and exhaust sides can be distributed by the length and angle of the inclined surface to simulate the uneven state of the thermal load on the intake and exhaust sides; when determining the load of the loading rod, such as Figure 2 As shown, the linear relationship between the loading load, stress at dangerous parts and safety factor is found by using the finite element analysis method of linear increase of loads at multiple load parts, and the appropriate loading load is determined, and then the loading load is converted into the installation preload.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for simulating engine cylinder head load, comprising the following steps: S1. Install the fastening device to the surface of the cylinder head; S2. Extend the loading rod into the oil injection hole or air passage through the fastening device; S3, simulating the uneven state of thermal load on the intake and exhaust sides by loading the rod; S4, determining the load of the loading rod; S5. Convert the loading load into the installation preload; The fastening device is in the shape of a rectangular block, and comprises a fastening block and a loading rod body. The fastening block is provided with a No. 1 screw hole, a No. 2 screw hole and a matching hole. Bolts are respectively passed through the No. 1 screw hole and the No. 2 screw hole to fix the fastening block on the surface of the cylinder head. The fastening block is also provided with a matching hole, and the matching hole corresponds to the injection hole or the air passage. The loading rod body passes through the matching hole and is placed in the injection hole or the air passage. The loading rod includes a straight rod and a carrier, wherein one side of the bottom of the straight rod is an inclined surface structure, the ratio of the inclined surface length to the diameter of the straight rod is 1:3-1:4; the angle of the inclined surface and the horizontal plane is 30°-45°; the carrier is installed on the inclined surface of the straight rod.

2. The method for simulating engine cylinder head load according to claim 1, characterized in that: An internal thread is arranged at the opening of the matching hole, and an external thread is arranged on the surface of the loading rod body, so as to realize the threaded connection between the loading rod body and the matching hole.

3. The method for simulating engine cylinder head load according to claim 1, characterized in that: In S4, the linear increase analysis method of multiple load parts using finite element is used to find the linear relationship between the loading load and the stress and safety factor of the dangerous parts, and determine the appropriate loading load.

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