A low contact stress rocker shaft assembly

Abstract

The application relates to the field of engine valve train, and particularly discloses a rocker arm shaft assembly with low contact stress, which comprises 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 the shape of a nut, 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 a cam shaft cover seat 5 through a bearing, the cam shaft cover seat 5 is designed with a pit matched with the head of a cylinder head long bolt 6, the cylinder head long bolt 6 is designed in a staggered manner with the cam shaft cover seat 5 through the pit; 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 installed on the engine cylinder head 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 application has the advantages of reasonable design and convenient installation, and the contact stress is reduced through the cam shaft cover seat, the optimization of the rigidity of the two sides of the roller and the inner roller shape.

Description

TECHNICAL FIELD

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

[0002] In the valve train of an engine, the rocker shaft assembly is a key transmission component, which is subjected to combined forces from the camshaft, the rocker shaft itself and the valve bridge during operation. When the action lines of these forces are not coplanar, i.e. not in the same vertical plane, the force offset phenomenon will occur, resulting in non-uniform load distribution, which is called the eccentric load. The existence of the eccentric load will exacerbate the stress concentration in the contact area between the camshaft and the rocker roller, and 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 assembly, thereby affecting its durability and shortening its service life.

[0003] Therefore, a low contact stress rocker shaft assembly is expected. SUMMARY

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

[0005] The rocker further comprises an intake rocker and an exhaust rocker, which are installed on the engine cylinder head through the rocker shaft, and a rocker shaft fastening bolt is installed near the exhaust rocker;

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

[0007] In particular, the low contact stress rocker shaft assembly further comprises a valve bridge, which is connected with the second end of the rocker through a valve adjusting 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 of the inner roller is an arc surface, and the second side is a cylindrical surface, and the shape of the arc surface is determined according to the deformation / tilt angle of the roller under the eccentric load.

[0010] In particular, the outer roller has a cylindrical surface on both sides, and the first side of the inner roller is in contact with the outer roller.

[0011] Compared with the prior art, the low-contact-stress rocker shaft assembly provided by the application reduces the eccentric load and contact stress by designing a recess matching the head of the cylinder cover long bolt on the camshaft cover seat, adjusting the wall thickness of the roller, and optimizing the shape of the inner roller, thereby prolonging the service life of the rocker assembly. BRIEF DESCRIPTION OF DRAWINGS

[0012] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description of embodiments of the present application, when taken in conjunction with the accompanying drawings. The drawings provided in the present application are used to provide further understanding of the embodiments of the present application, and constitute a part of the specification, and are used to explain the present application together with the embodiments of the present application, and do not constitute a limitation of the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0013] Figure 1 FIG. 1 illustrates a schematic diagram of the overall structure of a low-contact-stress rocker shaft assembly according to an embodiment of the present application.

[0014] Figure 2 FIG. 2 illustrates a load eccentricity diagram of a low-contact-stress rocker shaft assembly according to an embodiment of the present application.

[0015] Figure 3 FIG. 3 illustrates a misalignment detail view of an exhaust rocker of a low-contact-stress rocker shaft assembly according to an embodiment of the present application.

[0016] Figure 4 FIG. 4 illustrates a schematic diagram of a give structure of a low-contact-stress rocker shaft assembly according to an embodiment of the present application.

[0017] Figure 5 FIG. 5 illustrates a give effect display diagram of a low-contact-stress rocker shaft assembly according to an embodiment of the present application.

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

[0019] Figure 7 FIG. 7 illustrates a rocker roller comparison diagram of a low-contact-stress rocker shaft assembly according to an embodiment of the present application.

[0020] Figure 8 FIG. 8 illustrates a schematic diagram of a roller structure of a low-contact-stress rocker shaft assembly according to an embodiment of the present application.

[0021] 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, 6 cylinder head long bolt, 7 rocker shaft fastening bolt, 8 valve bridge, 9 valve adjusting screw. DETAILED DESCRIPTION

[0022] Hereinafter, exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and thus are not to be taken to limit the whole embodiments of the present application, and it should be appreciated that the present application is not limited to the exemplary embodiments described here.

[0023] Embodiment:

[0024] As shown in Figure 1 and Figure 2 , the low contact stress rocker shaft assembly 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 with the cam 31 on the camshaft 3 through the roller 4; the second end of the rocker arm 1 is in the shape of a nut and is connected with the valve bridge 8 through a valve adjusting 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 train, and these components work together to ensure that the valve train process of the engine 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 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. During engine operation, the rocker shaft fastening bolt 7 helps to transmit the force transmitted by 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 rocker shaft assembly valve train will bear the force applied by the camshaft 3, the rocker shaft 2 and the valve bridge 8. However, during the operation cycle of the engine, if the action lines of the three groups of forces deviate from the same plane, as shown in Figure 2 and 3 , the center of the roller 4 of the right red exhaust rocker arm 12 and the valve adjusting screw 9 are not in the same vertical plane, and the force of the camshaft and the valve bridge is misaligned (the misalignment is the distance between the pink and green planes in the figure), thereby generating a partial load and increasing the contact stress of the camshaft 3 and the roller 4. As the misalignment distance of the force rises, the partial load problem becomes more serious, and the peak value of the contact stress also rises, which will lead to more serious wear of the rocker assembly, thereby reducing its service life.

[0027] In particular, as shown in Figure 4 and 6 , the camshaft 3 is connected to the camshaft cover seat 5 through a bearing. In the original design, the cylinder head long 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 far away from the cylinder head long bolt 6, resulting in a large misalignment offset between the exhaust rocker arm 12 and the valve bridge 8. Therefore, in order to reduce the eccentric load and contact stress, ensure the long-term operation of the rocker arm assembly, and further optimize the design of the rocker arm shaft assembly, it is necessary 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, and to reduce the eccentric load phenomenon.

[0028] Specifically, as shown in Figure 4 and Figure 5 , the cylinder head long bolt 6 below the camshaft cover seat 5 is designed to be accommodated, shortening the distance between the installation hole of the rocker shaft fastening bolt 7 and the cylinder head long bolt 6, and shortening the position of the exhaust rocker arm 12 and the valve bridge 8. That is, a bolt head-shaped recess is designed on the camshaft cover seat 5, the shape of the recess matches the head of the cylinder head long bolt 6, and when the cylinder head long bolt 6 is installed, the bolt head will be embedded in the recess. As shown in Figure 6 , this design not only ensures that the cylinder head long bolt 6 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 bolt 7 and the cylinder head long bolt 6. Such a design allows the exhaust rocker arm 12 to move towards the cylinder head long bolt 6, thereby reducing the offset of the roller 4 of the exhaust rocker arm 12 and the valve adjusting 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 difficult to cast.

[0029] In addition, as shown in Figure 7 , due to the thin left wall and thick right wall of the roller installation groove of the exhaust rocker arm 12, the contact stress distribution on both sides of the roller 4 is uneven, resulting in an eccentric load phenomenon, that is, the stress on one side of the roller 4 when it contacts the camshaft 3 may be greater than that on the other side. Therefore, the left wall thickness of the roller 4 is adjusted to increase the support stiffness of the rocker arm 1, thereby balancing the contact stress on both sides of the roller 4 and reducing wear. Specifically, the left wall thickness of the roller installation groove is supplemented, where the left wall thickness is slightly thinner than the right wall, thereby increasing the left stiffness and its contact stress (4% to 8%), achieving the purpose of reducing the right (wearing side) contact stress (3% to 7%).

[0030] In particular, as shown in Figure 1 and Figure 8As shown, the roller 4 includes an inner roller 41 and an outer roller 42, wherein the first side of the inner roller 41 is an arc surface and the second side is a cylindrical surface, wherein the shape of the arc surface is determined according to the deformation / tilt angle of the roller 4 under the eccentric load condition; the two sides of the outer roller 42 are both cylindrical surfaces. The first side 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 tilt 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 low contact stress rocker shaft assembly according to the embodiments of the present application is illustrated, which includes a rocker 1, a rocker shaft 2 and a camshaft 3, wherein the first end of the rocker 1 is provided with a roller mounting groove, the second end is in the shape of a nut, the first end is connected with the cam 31 on the camshaft 3 through the roller 4, the camshaft 3 is connected with the camshaft cover seat 5 through a bearing, the camshaft cover seat 5 is designed with a recess matching the head of the cylinder head long bolt 6, through the recess, the cylinder head long bolt 6 is designed in a staggered manner with the camshaft cover seat 5; the rocker 1 further includes an intake rocker 11 and an exhaust rocker 12, the intake rocker 11 and the exhaust rocker 12 are installed on the engine cylinder head through the rocker shaft 2, and the rocker shaft fastening bolt 7 is installed on the side close to the exhaust rocker 12. The present application has reasonable design and is easy to install, which realizes the reduction of contact stress through the camshaft cover seat accommodation, the optimization of the stiffness of the two sides of the roller and the shape of the inner roller.

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

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting, and although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit of the present application.

Claims

1. A rocker arm shaft assembly with low contact stress, characterized in that, include: The rocker arm (1), rocker arm shaft (2) and cam shaft (3) are provided. The first end of the rocker arm (1) is provided with a roller mounting groove and the second end is nut-shaped. The first end of the rocker arm (1) is connected to the cam (31) on the cam shaft (3) through a roller (4). 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 mounted on the engine cylinder head via the rocker arm shaft (2). A rocker arm shaft fastening bolt (7) is installed on the side near 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 bolt (6). The cylinder head bolt (6) is embedded in the camshaft cover seat (5) through the recess to shorten the distance between the rocker arm shaft fastening bolt (7) and the cylinder head bolt (6), allowing the exhaust rocker arm (12) to move toward the cylinder head bolt (6) and reducing the offset of the roller (4) of the exhaust rocker arm (12) and the valve adjusting screw (9) in the vertical plane. The wall thickness of the roller mounting groove on the left side near the rocker arm shaft fastening bolt (7) is increased, wherein the wall thickness on the left side of the roller mounting groove is slightly thinner than that on the right side.

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

3. The rocker arm shaft assembly with low contact stress according to claim 2, characterized in that, The roller (4) includes an inner roller (41) and an outer roller (42), wherein the first side of the inner roller (41) is radially outer and the second side is radially inner. The shape of the arc surface is determined according to the deformation / tilt angle of the roller (4) under eccentric loading.

4. The rocker arm shaft assembly with low contact stress according to claim 3, characterized in that, The outer roller (42) has cylindrical surfaces on both its inner and outer radial sides, and the first side of the inner roller (41) is in contact with the outer roller (42).

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