Method and device for analyzing eccentric wear of camshaft
By establishing a three-dimensional model of the camshaft and rocker arm and conducting finite element analysis, and calculating the contact data between the roller and the camshaft, the problem of large errors in camshaft wear detection was solved, achieving more accurate eccentric wear judgment and engine performance optimization.
Patent Information
- Application Number
- CN202410250252.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-05
- Publication Date
- 2025-09-05
AI Technical Summary
In the existing technology, the camshaft wear detection error is large, which leads to the disruption of the engine valve opening pattern, increased fuel consumption and impure exhaust emissions.
By building a three-dimensional model of the camshaft and rocker arm, meshing and adding valve support reaction force, the contact data between the roller and the camshaft is calculated using finite element analysis software to determine whether the contact stress difference exceeds the preset error range to determine uneven wear.
It achieves more accurate camshaft eccentric wear detection, reduces errors, facilitates real-time adjustment of model structure, and improves engine performance.
Smart Images
Figure CN120597400A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of engine parts manufacturing, and in particular to a method and device for analyzing camshaft eccentric wear. Background Art
[0002] Rocker arms, camshafts, and rollers are all crucial engine components. When the camshaft rotates, the rollers in contact with the camshaft roll, driving the rocker arms in an up-and-down reciprocating motion, thereby controlling the opening and closing of the engine valves. Camshaft wear disrupts the engine's valve opening pattern, leading to insufficient airflow, incomplete exhaust emissions, and increased fuel consumption. Existing methods primarily use a micrometer to measure the diameter and height of the camshaft lobe to determine if uneven wear is occurring, but this method suffers from significant errors. Summary of the Invention
[0003] The purpose of the embodiment of the present invention is to provide a method and device for analyzing camshaft eccentric wear to solve the above-mentioned problems in the prior art. The method comprises: building a three-dimensional model of the camshaft and rocker arm; the three-dimensional model of the camshaft and rocker arm includes the camshaft, rocker arm, and roller;
[0004] Meshing the three-dimensional models of the camshaft and rocker arm, and adding valve branch reaction forces to establish finite element models of the camshaft and rocker arm; and
[0005] Using finite element analysis software to simulate and calculate the finite element model of the camshaft and the rocker arm, and determine contact data generated by rolling contact between the roller and the camshaft after adding the valve support reaction force, wherein the contact data includes: contact stress between the two ends of the roller and the camshaft;
[0006] When the difference in contact stress between the two ends of the roller and the camshaft exceeds a preset error range, it is determined that the camshaft has suffered eccentric wear.
[0007] Optionally, the contact data further includes:
[0008] a contact gap between both ends of the roller contacting the camshaft, and a tilting angle between the roller and the camshaft.
[0009] Optionally, a database is established to store the three-dimensional model of the camshaft and the rocker arm, the finite element model of the camshaft and the rocker arm, and the corresponding contact data simulated and calculated by the finite element analysis software.
[0010] Optionally, the corresponding contact gap values between the two ends of the roller and the camshaft are measured in advance; and a three-dimensional model of the camshaft and the rocker arm is established using the measured corresponding contact gap values between the two ends of the roller and the camshaft.
[0011] Optionally, an engine valve mounting position is provided on the rocker arm;
[0012] The valve branch reaction force is applied to the engine valve installation position.
[0013] Optionally, the camshaft rotates, driving the connected roller to rotate, and the roller rotates to drive the engine valve to move up and down, thereby controlling the corresponding opening and closing of the engine valve.
[0014] Optionally, the three-dimensional model of the camshaft and rocker arm further includes: a roller pin, a rocker arm roller, and a rocker arm mounting seat.
[0015] Optionally, when establishing the finite element models of the camshaft and the rocker arm, the manufacturing material information corresponding to the camshaft, the rocker arm and the roller is added.
[0016] Optionally, the finite element analysis software is ANSYS.
[0017] Another aspect of an embodiment of the present invention provides a device for analyzing camshaft eccentric wear. The device includes a memory and a processor, and the processor is configured to execute the method for analyzing camshaft eccentric wear.
[0018] Through the above technical solution, the present invention first establishes a three-dimensional model of the camshaft and rocker arm, then meshes the three-dimensional model of the camshaft and rocker arm, and adds valve support reaction force to establish a finite element model of the camshaft and rocker arm, and then uses finite element analysis software to solve the contact data generated by the rolling contact between the roller and the camshaft after adding the valve support reaction force. Finally, it is determined whether the camshaft has eccentric wear based on the contact data. This method has a small error, is easy to apply and implement, and can adjust the model structure in real time according to design requirements.
[0019] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:
[0021] Figure 1 is a flow chart of a method for analyzing camshaft eccentric wear provided by an embodiment of the present invention;
[0022] Figure 2 Schematic diagram of the combined structure of a camshaft and a rocker arm provided by an embodiment of the present invention;
[0023] Figure 31 is a schematic structural diagram of a rocker arm provided by an embodiment of the present invention;
[0024] Figure 4 is a cross-sectional schematic diagram corresponding to the rolling contact between the roller and the camshaft provided by an embodiment of the present invention;
[0025] Figure 5 is a schematic diagram of contact stress distribution corresponding to a first contact surface between a roller and a camshaft provided by an embodiment of the present invention;
[0026] Figure 6 It is a schematic diagram of the contact stress distribution corresponding to the second contact surface between the roller and the camshaft provided by an embodiment of the present invention.
[0027] Description of Reference Numerals
[0028] 1. Camshaft
[0029] 2. Roller pin
[0030] 3. Roller
[0031] 4. Rocker roller
[0032] 5. Rocker arm mounting bracket
[0033] 6. Rocker arm
[0034] 7. Engine valve installation position DETAILED DESCRIPTION
[0035] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.
[0036] Figure 1 FIG. 1 is a flow chart of a method for analyzing camshaft eccentric wear provided by an embodiment of the present invention; FIG. Figure 1 As shown, the method for analyzing camshaft eccentric wear includes:
[0037] Step S101: construct a three-dimensional model of the camshaft and the rocker arm, wherein the three-dimensional model of the camshaft and the rocker arm includes the camshaft, the rocker arm, and the roller.
[0038] Specifically, the camshaft is a core component in the engine, controlling the opening and closing of the engine valves. This includes controlling the opening and closing time, the degree of opening, and the degree of closing of the valves, thereby controlling the inflow and outflow of fuel into the combustion chamber and ensuring proper engine operation. The valve opening degree and opening time directly affect the amount of mixed gas entering and exiting the combustion chamber and the emission effect.
[0039] Figure 2: is a schematic diagram of the combined structure of the camshaft and the rocker arm provided in an embodiment of the present invention, Figure 3 Schematic diagram of the structure of the rocker arm provided by the embodiment of the present invention. Figure 2 、 Figure 3 The three-dimensional model of the camshaft and rocker arm includes a camshaft 1, a rocker arm 6, and a roller 3. The rocker arm is provided with an engine valve mounting position 7, and the engine valve is mounted on the engine valve mounting position provided on the rocker arm.
[0040] Specifically, when the camshaft rotates, the roller in contact with the camshaft rolls, driving the rocker arm to move up and down, thereby controlling the corresponding opening and closing of the engine valve.
[0041] Figure 4 FIG. 1 is a cross-sectional schematic diagram corresponding to the rolling contact between the roller and the camshaft provided by an embodiment of the present invention, as shown in FIG. Figure 4 As shown, when the camshaft and roller are in contact, the left side of the roller ( Figure 4 The right side of the roller (S1 side) contacts the camshaft, forming the first contact surface between the two. Figure 4 The middle S2 side) contacts the camshaft, forming a second contact surface between the two.
[0042] In some embodiments, the 3D model of the camshaft and rocker arm further includes a roller pin 2, a rocker roller 4, and a rocker arm mounting bracket 5. The rocker arm mounting bracket is connected to the rocker arm and supports and secures the rocker arm. The rocker arm reciprocates up and down by rolling around the rocker roller. The roller pin is used to position and secure the roller, which rolls around the roller pin.
[0043] In some embodiments, a three-dimensional model of the camshaft and rocker arm is created based on a geometric solid model of the camshaft and rocker arm. Drawings of the camshaft and rocker arm are collected in advance to determine the dimensions of their components, the connections between them, and the forces acting between them. The three-dimensional model of the camshaft and rocker arm is then created based on the dimensions, connections, and forces acting between them.
[0044] Specifically, the corresponding contact gap values between the two ends of the roller and the camshaft are measured in advance; and the three-dimensional model of the camshaft and the rocker arm is established using the measured corresponding contact gap values between the two ends of the roller and the camshaft.
[0045] In some embodiments, the relevant parameters of the camshaft cam can also be measured in advance, including: cam profile, cam height, curvature of the cam protrusion, cam thickness, and cam surface finish. The three-dimensional model of the camshaft and rocker arm can be established using the measured relevant parameters of the camshaft cam.
[0046] It's important to note that the geometric shapes of the camshaft and rocker arm can be mathematically expressed using modeling software such as CAD, CATIA, UG, and Pro / E. Specifically, a 3D model of the camshaft and rocker arm is first created using the modeling software. This model is then further divided into nodes and elements, and finally, the resulting 3D model is input into finite element analysis software for further processing. The 3D model can also be created directly within the finite element analysis software.
[0047] Step S102 : meshing the three-dimensional model of the camshaft and the rocker arm, and adding valve branch reaction force to establish a finite element model of the camshaft and the rocker arm.
[0048] Specifically, meshing can be used to divide the 3D model of the camshaft and rocker arm into many small elements, allowing them to be converted into corresponding finite element models. Meshing directly impacts solution accuracy, convergence, and speed. The meshing format directly influences the subsequent calculation accuracy and scale of the finite element analysis software. Meshes are categorized into free, mapped, and swept meshes.
[0049] After meshing is complete and the corresponding finite element model is generated, you can preview it to check whether the generated finite element model meets the actual requirements. If it does not meet the requirements, you can re-mesh it. It should be noted that although further refining the mesh can make the results more accurate, it will increase the computational overhead of hardware resources, extend the calculation time, and require more storage space. Therefore, it is necessary to balance the contradiction between computational cost and mesh refinement.
[0050] In some embodiments, when building a finite element model of the camshaft and rocker arm, loads and constraints are added to the geometric boundaries of the model. Specifically, in actual engineering, a component of a device is always interconnected with other surrounding components in a certain manner. This means that the movement of an object is restricted by other surrounding objects. These surrounding objects that restrict certain displacements of the object are called constraints. Loads refer to external forces, such as gravity and thermal loads, acting on the structural system. Types of loads mainly include static loads, dynamic loads, temperature loads, and prestressed loads.
[0051] It should be noted that during the use of rocker arms, rollers, and camshafts, there is a support reaction force at the contact point between the rocker arm and the valve. Specifically, support reaction force, also known as supporting reaction force or support reaction force, refers to the vertical reaction force borne by each support point during the operation of lifting and transportation machinery or other equipment. This reaction force is generated by the movement of the equipment or the support device being subjected to external forces, and acts on the support device.
[0052] When establishing a finite element model of the camshaft and the rocker arm, the valve branch reaction force is applied to the engine valve installation position on the rocker arm of the finite element model.
[0053] In some embodiments, when building the finite element models of the camshaft and rocker arm, material information corresponding to the camshaft, rocker arm, and roller is added, such as ductile iron, malleable iron, gray cast iron, carbon steel, rimmed steel, high-manganese low-carbon permeable steel, etc. Each material includes elastic modulus, Poisson's ratio, and mass density.
[0054] Step S103: using finite element analysis software to perform simulation calculations on the finite element models of the camshaft and the rocker arm to determine contact data generated by rolling contact between the roller and the camshaft after adding the valve support reaction force.
[0055] The contact data includes the contact stress between the roller and the camshaft at both ends. Specifically, when the camshaft rotates, the roller in contact with the camshaft rolls, driving the rocker arm to reciprocate up and down. This generates contact stress between the roller and the camshaft at both ends. Due to the inconsistent stiffness of the rocker arm, the forces acting on both ends of the roller are inconsistent. The side with greater force will cause uneven wear on the side in contact with the camshaft. Stiffness refers to the ability of a component or structure to resist deformation when under load.
[0056] In some embodiments, the contact data further includes: a contact gap between the two ends of the roller and the camshaft, a tilting angle between the roller and the camshaft, and a distribution of contact stress between the roller and the camshaft.
[0057] Specifically, Figure 5 : is a schematic diagram of contact stress distribution corresponding to the first contact surface between the roller and the camshaft provided by an embodiment of the present invention, Figure 6 It is a schematic diagram of the contact stress distribution corresponding to the second contact surface between the roller and the camshaft provided by an embodiment of the present invention.
[0058] Step S104: When the difference in contact stress between the two ends of the roller and the camshaft exceeds a preset error range, it is determined that the camshaft has eccentric wear.
[0059] Specifically, refer to Figure 5 、 Figure 6 Based on the stress distribution between the first and second contact surfaces of the roller and the camshaft, a first average stress value between the first contact surface of the roller and the camshaft and a second average stress value between the second contact surface of the roller and the camshaft can be calculated. The difference between the first average stress value and the second average stress value is determined. If the difference between the first average stress value and the second average stress value exceeds a preset error range, it is determined that the camshaft has experienced eccentric wear.
[0060] In some embodiments, it is also possible to determine whether the camshaft has eccentric wear based on the contact gap between the roller and the two ends of the camshaft. For details, refer to Figure 4 , the left contact position between the camshaft and the roller ( Figure 4 The contact gap between the camshaft and the roller (S1 position) is the first contact gap, and the right contact position of the camshaft and the roller ( Figure 4 The contact gap between the first contact gap and the second contact gap is calculated. When the difference between the first contact gap and the second contact gap is greater than a preset threshold, it is determined that the camshaft has eccentric wear.
[0061] In some embodiments, it is also possible to determine whether the camshaft has eccentric wear based on the tilt angle of the roller and the camshaft during operation. Figure 4 The first tilt angle is the angle between the roller axis and the camshaft axis bracket during assembly, and the second tilt angle is the angle between the roller axis and the camshaft axis during operation. When the second tilt angle exceeds a preset threshold, the camshaft is determined to have eccentric wear. It should be noted that when the roller and camshaft are in operation, the smaller the second tilt angle, the less likely eccentric wear will occur.
[0062] In some embodiments, a wear experiment can be designed in advance to induce eccentric wear on the camshaft. The difference in average contact stress between the roller and the camshaft at both ends of the contact state during eccentric wear is measured, and a range of differences used to determine camshaft wear is determined based on this difference in average contact stress. Accordingly, the contact gap between the roller and the camshaft at both ends during eccentric wear, as well as the tilt angle between the roller and the camshaft, can also be measured to set corresponding judgment thresholds.
[0063] In some embodiments, a database can be established to store the three-dimensional model of the camshaft and rocker arm, the finite element model of the camshaft and rocker arm, and the corresponding contact data calculated by the finite element analysis software, to facilitate reference and comparison for later design and analysis. Specifically, various database software such as MySQL, SQLite, and Oracle can be used for data storage, with MySQL being preferred.
[0064] In some embodiments, the finite element analysis software is ANSYS. It should be noted that various finite element analysis software such as Algor, HyperMesh, and ABAQUS can also be used.
[0065] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.
Claims
1. A method for analyzing camshaft eccentric wear, characterized in that: The method includes: Build a three-dimensional model of the camshaft and rocker arm; the three-dimensional model of the camshaft and rocker arm includes the camshaft, rocker arm, and roller; Meshing the three-dimensional models of the camshaft and rocker arm, and adding valve branch reaction forces to establish finite element models of the camshaft and rocker arm; and Using finite element analysis software to simulate and calculate the finite element model of the camshaft and the rocker arm, and determine contact data generated by rolling contact between the roller and the camshaft after adding the valve support reaction force, wherein the contact data includes: contact stress between the two ends of the roller and the camshaft; When the difference in contact stress between the two ends of the roller and the camshaft exceeds a preset error range, it is determined that the camshaft has suffered eccentric wear.
2. The method according to claim 1, characterized in that The contact data also includes: a contact gap between both ends of the roller contacting the camshaft, and a tilting angle between the roller and the camshaft.
3. The method according to claim 1, characterized in that A database is established to store the three-dimensional model of the camshaft and the rocker arm, the finite element model of the camshaft and the rocker arm, and the corresponding contact data calculated by the finite element analysis software simulation.
4. The method according to claim 1, wherein The corresponding contact gap values between the two ends of the roller and the camshaft are measured in advance; and a three-dimensional model of the camshaft and the rocker arm is established using the measured corresponding contact gap values between the two ends of the roller and the camshaft.
5. The method according to claim 1, wherein The rocker arm is provided with an engine valve mounting position; The valve branch reaction force is applied to the engine valve installation position.
6. The method according to claim 5, characterized in that The camshaft rotates to drive the connected roller to rotate, and the rotation of the roller drives the engine valve to move up and down, thereby controlling the corresponding opening and closing of the engine valve.
7. The method according to claim 1, characterized in that The three-dimensional model of the camshaft and rocker arm also includes: a roller pin, a rocker arm roller, and a rocker arm mounting seat.
8. The method according to claim 1, characterized in that When establishing the finite element model of the camshaft and rocker arm, add the manufacturing material information corresponding to the camshaft, rocker arm and roller respectively.
9. The method according to claim 1, characterized in that The finite element analysis software is ANSYS.
10. A device for analyzing camshaft eccentric wear, characterized in that: The apparatus includes a memory and a processor, wherein the processor is configured to execute the method according to any one of claims 1 to 9.