Rocker arm shaft assembly with low contact stress

Abstract

The invention relates to the field of engine valve mechanisms, and particularly discloses a low-contact-stress rocker arm shaft assembly which comprises a rocker arm 1, a rocker arm shaft 2 and a cam shaft 3, the first end of the rocker arm 1 is provided with a roller mounting groove, the second end of the rocker arm 1 is in a nut shape, and the first end is connected with a cam 31 on the cam shaft 3 through a roller 4; the cam shaft 3 is connected with the cam shaft cover seat 5 through a bearing, a pit matched with the head of the cylinder cover long bolt 6 is designed on the cam shaft cover seat 5, and the cylinder cover long bolt 6 and the cam shaft cover seat 5 are designed in a staggered manner through the pit; the rocker arm 1 further comprises an air inlet rocker arm 11 and an exhaust rocker arm 12, the air inlet rocker arm 11 and the exhaust rocker arm 12 are installed on an engine cylinder cover through the rocker arm shaft 2, and a rocker arm shaft fastening bolt 7 is installed on the side close to the exhaust rocker arm 12. The cam shaft cover seat is reasonable in design and convenient to install, the rigidity of the two sides of the roller and the appearance of the inner roller are optimized through receding of the cam shaft cover seat, and contact stress is reduced.

Description

Technical Field

[0001] The present application relates to the field of engine valve train, and more particularly, to a rocker shaft assembly with low contact stress. Background Art

[0002] In the engine's valve train, the rocker arm shaft assembly is a key transmission component that is subjected to the combined forces of the camshaft, the rocker arm shaft itself, and the valve bridge during operation. When the lines of action of these forces are not coplanar, that is, not in the same vertical plane, it will cause force offset, resulting in non-uniform load distribution, a phenomenon known as eccentric loading. The presence of eccentric loading will aggravate the stress concentration in the contact area between the camshaft and the rocker arm roller, especially when the force offset increases, the peak value of the contact stress will also increase. This stress concentration phenomenon will accelerate the wear process of the rocker arm assembly, thereby affecting its durability and shortening its service life.

[0003] Therefore, a rocker shaft assembly with low contact stress is desired. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides the following technical solutions: a rocker shaft assembly with low contact stress, comprising: a rocker arm, a rocker shaft and a camshaft, wherein the first end of the rocker arm is provided with a roller mounting groove and the second end is in a nut shape, and the first end of the rocker arm is connected to the cam on the camshaft through a roller.

[0005] The rocker arm further comprises an intake rocker arm and an exhaust rocker arm, wherein the intake rocker arm and the exhaust rocker arm are mounted on the engine cylinder head through the rocker arm shaft, and a rocker arm shaft fastening bolt is mounted on one side close to the exhaust rocker arm;

[0006] The camshaft is connected to the camshaft cover seat through a bearing. The camshaft cover seat is designed with a pit matching the head of the long bolt of the cylinder head. The long bolt of the cylinder head is embedded and installed on the camshaft cover seat through the pit.

[0007] In particular, the rocker arm shaft assembly with low contact stress further comprises a valve bridge, and the valve bridge is connected to the second end of the rocker arm through a valve adjustment screw.

[0008] In particular, the wall thickness of the left side of the roller mounting groove is supplemented, wherein the wall thickness of the left side of the roller mounting groove is slightly thinner than that of the right side.

[0009] In particular, the roller comprises an inner roller and an outer roller, wherein the first side surface of the inner roller is an arc surface, and the second side surface is a cylinder, wherein the shape of the arc surface is determined according to the deformation / inclination angle of the roller under an eccentric load condition.

[0010] Particularly, both sides of the outer roller are cylindrical surfaces, and the first side surface of the inner roller is in contact with the outer roller.

[0011] Compared with the prior art, the present application provides a rocker arm shaft assembly with low contact stress, which reduces the eccentric load and contact stress and extends the service life of the rocker arm assembly by designing a pit on the camshaft shaft cover seat that matches the head of the long bolt of the cylinder head, adjusting the roller wall thickness and optimizing the shape of the inner roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0013] Figure 1 The figure shows a schematic diagram of the overall structure of a rocker shaft assembly with low contact stress according to an embodiment of the present application.

[0014] Figure 2 The figure shows an eccentric load display diagram of a rocker shaft assembly with low contact stress according to an embodiment of the present application.

[0015] Figure 3 A detailed view of misalignment of an exhaust rocker arm in a rocker shaft assembly with low contact stress according to an embodiment of the present application is illustrated.

[0016] Figure 4 The figure shows a schematic diagram of the yield structure of the rocker shaft assembly with low contact stress according to an embodiment of the present application.

[0017] Figure 5 The diagram illustrates the yielding effect of a rocker shaft assembly with low contact stress according to an embodiment of the present application.

[0018] Figure 6 The diagram illustrates a comparison diagram of the yielding of a rocker shaft assembly with low contact stress according to an embodiment of the present application.

[0019] Figure 7 A comparison diagram of a rocker arm roller of a rocker arm shaft assembly with low contact stress according to an embodiment of the present application is illustrated.

[0020] Figure 8 The figure shows a schematic diagram of the roller structure of the rocker shaft assembly with low contact stress according to an embodiment of the present application.

[0021] In the figure: 1 rocker arm, 11 intake rocker arm, 12 exhaust rocker arm, 2 rocker shaft, 3 camshaft, 31 cam, 4 roller, 41 inner roller, 42 outer roller, 5 camshaft cover seat, 6 cylinder head long bolts, 7 rocker shaft fastening bolts, 8 valve bridge, 9 valve adjustment screws. DETAILED DESCRIPTION

[0022] Below, exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the exemplary embodiments described here.

[0023] Example:

[0024] like Figure 1 and Figure 2 As shown, the rocker shaft assembly with low contact stress of the embodiment of the present application comprises: a rocker arm 1, a rocker shaft 2, a camshaft 3 and a valve bridge 8, wherein the first end of the rocker arm 1 is provided with a roller mounting groove for mounting a roller 4, and the first end of the rocker arm 1 is connected to the cam 31 on the camshaft 3 through the roller 4; the second end of the rocker arm 1 is in a nut shape and is connected to the valve bridge 8 through a valve adjustment screw 9. Based on this, the precise control of the camshaft 3, the leverage of the rocker arm 1, the stability of the rocker shaft 2 and the synchronization of the valve bridge 8 together constitute the core function of the engine valve mechanism, and these components work together to ensure that the engine valve process is carried out according to the design requirements, thereby ensuring the efficient operation of the engine.

[0025] In particular, the rocker arm 1 further comprises an intake rocker arm 11 and an exhaust rocker arm 12, which are mounted on the engine cylinder head via the rocker arm shaft 2, and a rocker arm shaft fastening bolt 7 is mounted on a side close to the exhaust rocker arm 12. When the engine is working, the rocker arm shaft fastening bolt 7 helps transmit the force transmitted from the camshaft 3 to the valve through the rocker arm 1, ensuring that the valve can be correctly opened and closed according to the design requirements.

[0026] During the operation of the engine, the valve train of the rocker shaft assembly will be subjected to the forces applied by the camshaft 3, the rocker shaft 2 and the valve bridge 8. However, during the operation cycle of the engine, if the lines of action of the three groups of forces deviate from the same plane, such as Figure 2 and 3 As shown, the center of the roller 4 of the right red exhaust rocker arm 12 is not in the same vertical plane as the valve adjustment screw 9, and the forces received from the camshaft and the valve bridge are misaligned (the misalignment is the distance between the pink and green planes in the figure), which results in an eccentric load and increases the contact stress between the camshaft 3 and the roller 4. As the force misalignment distance increases, the eccentric load problem becomes more serious, and the peak value of the contact stress also increases, which will cause more severe wear of the rocker arm assembly, thereby reducing its service life.

[0027] In particular, if Figure 4 and 6 As shown, the camshaft 3 is connected to the camshaft cover seat 5 through a bearing. In the original design, a long cylinder head bolt 6 is installed on the side of the camshaft cover seat 5 away from the exhaust rocker arm 12. This design makes the installation hole of the rocker shaft fastening bolt 7 and the long cylinder head bolt 6 have a large spacing, which leads to a large offset between the exhaust rocker arm 12 and the valve bridge 8. Therefore, in order to reduce the eccentric load and contact stress and ensure the long-term operation of the rocker arm assembly, the design of the rocker arm shaft assembly is further optimized to ensure that the force lines of the camshaft 3, the rocker arm shaft 2 and the valve bridge 8 are as coplanar as possible to reduce the eccentric load phenomenon.

[0028] Specifically, Figure 4 and Figure 5 As shown, the cylinder head long bolt 6 below the camshaft cover seat 5 is designed to give way, shorten the distance between the mounting hole of the rocker shaft fastening bolt 7 and the cylinder head long bolt 6, so that the position of the exhaust rocker arm 12 and the valve bridge 8 is shortened. That is, a bolt head-shaped pit is designed on the camshaft cover seat 5, and the shape of this pit matches the head of the cylinder head long bolt 6. When the cylinder head long bolt 6 is installed, the bolt head will be embedded in this pit. Figure 6 As shown, this design not only ensures that the long bolts 6 of the cylinder head will not interfere with the camshaft cover seat 5 during installation, but also optimizes the space below the camshaft cover seat 5, shortening the distance between the rocker shaft fastening bolts 7 and the long bolts 6 of the cylinder head. Such a design allows the exhaust rocker arm 12 to move toward the long bolts 6 of the cylinder head, thereby reducing the offset of the roller 4 of the exhaust rocker arm 12 and the valve adjustment screw 9 in the vertical plane, achieving the goal of reducing contact stress. However, the disadvantage of such a design is that the camshaft cover seat 5 is more difficult to cast.

[0029] In addition, if Figure 7 As shown, since the wall thickness of the roller mounting groove of the exhaust rocker arm 12 is thinner on the left side and thicker on the right side, the contact stress distribution on both sides of the roller 4 is uneven, resulting in an eccentric load phenomenon, that is, when the roller 4 contacts the camshaft 3, the stress on one side may be greater than that on the other side. Therefore, the wall thickness on the left side of the roller 4 is adjusted to enhance the supporting stiffness of the rocker arm 1, thereby balancing the contact stress on both sides of the roller 4 and reducing wear. Specifically, the wall thickness of the left side of the roller mounting groove is supplemented, wherein the wall thickness of the left side is slightly thinner than that of the right side, thereby increasing the stiffness and contact stress of the left side (4% to 8%), and achieving the purpose of reducing the contact stress on the right side (wear side) (3% to 7%).

[0030] In particular, if Figure 1 and Figure 8As shown, the roller 4 includes an inner roller 41 and an outer roller 42, wherein the first side surface of the inner roller 41 is an arc surface, and the second side surface is a cylinder surface, wherein the shape of the arc surface is determined according to the deformation / inclination angle of the roller 4 under the eccentric load; both sides of the outer roller 42 are cylinder surfaces. And the first side surface of the inner roller 41 is in contact with the outer roller 42. In this way, by optimizing the shape of the inner roller 41, the eccentric load inclination angle is compensated, so that the outer roller 42 and the cam 31 maintain good contact and reduce the contact stress.

[0031] In summary, the rocker shaft assembly with low contact stress according to the embodiment of the present application is explained, which includes: a rocker arm 1, a rocker shaft 2 and a camshaft 3, wherein the first end of the rocker arm 1 is provided with a roller mounting groove, the second end is in a nut shape, the first end is connected to the cam 31 on the camshaft 3 through the roller 4, the camshaft 3 is connected to the camshaft cover seat 5 through a bearing, the camshaft cover seat 5 is designed with a pit matching the head of the cylinder head long bolt 6, through the pit, the cylinder head long bolt 6 and the camshaft cover seat 5 are staggered; the rocker arm 1 also includes an intake rocker arm 11 and an exhaust rocker arm 12, the intake rocker arm 11 and the exhaust rocker arm 12 are installed on the engine cylinder head through the rocker shaft 2, and a rocker shaft fastening bolt 7 is installed near the exhaust rocker arm 12. The present application is reasonably designed and easy to install, and the contact stress is reduced by giving way to the camshaft cover seat, optimizing the rigidity of both sides of the roller and the shape of the inner roller.

[0032] It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit of the technical solution of the present invention.

Claims

1. A rocker shaft assembly with low contact stress, characterized in that: include: A rocker arm (1), a rocker arm shaft (2) and a cam shaft (3), wherein the first end of the rocker arm (1) is provided with a roller mounting groove, the second end is in a nut shape, and the first end of the rocker arm (1) is connected to a cam (31) on the cam shaft (3) via a roller (4); The rocker arm (1) further comprises an intake rocker arm (11) and an exhaust rocker arm (12); the intake rocker arm (11) and the exhaust rocker arm (12) are mounted on the engine cylinder head via the rocker arm shaft (2); a rocker arm shaft fastening bolt (7) is mounted on a side close to the exhaust rocker arm (12); The camshaft (3) is connected to the camshaft cover seat (5) via a bearing. The camshaft cover seat (5) is designed with a recess that matches the head of the cylinder head long bolt (6). The cylinder head long bolt (6) is embedded and installed on the camshaft cover seat (5) through the recess.

2. The rocker shaft assembly with low contact stress according to claim 1, characterized in that: It also comprises a valve bridge (8), wherein the valve bridge (8) is connected to the second end of the rocker arm (1) via a valve adjustment screw (9).

3. The rocker shaft assembly with low contact stress according to claim 2, characterized in that: The wall thickness of the left side of the roller mounting groove is supplemented, wherein the wall thickness of the left side of the roller mounting groove is slightly thinner than that of the right side.

4. The rocker shaft assembly with low contact stress according to claim 3, characterized in that: The roller (4) comprises an inner roller (41) and an outer roller (42), wherein the first side surface of the inner roller (41) is an arc surface, and the second side surface is a cylinder surface, wherein the shape of the arc surface is determined according to the deformation / inclination angle of the roller (4) under an eccentric load condition.

5. The rocker shaft assembly with low contact stress according to claim 4, characterized in that: Both sides of the outer roller (42) are cylindrical surfaces, and the first side surface of the inner roller (41) is in contact with the outer roller (42).

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