Valve rocker arm assembly

Abstract

The present invention relates to a valve rocker arm assembly. The valve rocker arm assembly includes a first rocker arm housing, a second rocker arm housing, and a first roller. The first roller is rotatably mounted on the first rocker arm housing. The second rocker arm housing has first and second side plates. The first rocker arm housing is rotatably mounted between the first and second side plates. The valve rocker arm assembly also includes a first roller pair and a second roller pair for jointly engaging a drive mechanism. The first roller pair includes two rollers rotatably coaxially mounted on opposite sides of the first side plate. The second roller pair includes two rollers rotatably coaxially mounted on opposite sides of the second side plate. The rotational axis of the first roller pair relative to the first side plate and the rotational axis of the second roller pair relative to the second side plate are respectively parallel to the rotational axis of the second rocker arm housing relative to the first rocker arm housing. The valve rocker arm assembly of the present invention can reduce wear and extend service life.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a valve rocker arm assembly for an engine system. Background Art

[0002] The valve train is a crucial component in a vehicle's engine system. Typically, the valve train includes a rocker arm mechanism that converts the cam's rotational motion into the linear motion of the valve pushrod. The rocker arm mechanism works in conjunction with the cam mechanism, controlling the timely opening and closing of the valves through its own swinging motion, thereby enabling intake and exhaust of the engine cylinders. A switchable roller finger follower (SRFF) typically comprises two pivotally connected rocker arm mechanisms. By controlling the connection between the two rocker arm mechanisms, the engagement state between the cam and the rocker arm mechanism can be changed, allowing the valve lift to switch between high and low lift or for the valve to open twice.

[0003] In the prior art, switchable valve rocker arms, such as those disclosed in CN 102892977 A, typically have two rocker arms, an inner rocker arm and an outer rocker arm. The inner rocker arm is rotatably mounted between the two side plates of the outer rocker arm. A roller assembly is mounted on the inner rocker arm, ensuring rolling contact with the cam that drives the valve rocker arm, thereby reducing friction between the two. Friction pads are provided on the two side plates of the outer rocker arm, respectively, for sliding contact with the cam. This design results in significant frictional losses between the outer rocker arm and the cam, which can easily cause wear and affect service life. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a valve rocker arm assembly that can reduce wear.

[0005] The above technical problems are solved by a valve rocker arm assembly according to the present invention. The valve rocker arm assembly includes a first rocker arm housing, a second rocker arm housing, and a first roller. The first rocker arm housing and the second rocker arm housing are rotatably connected to each other. The first roller is rotatably mounted on the first rocker arm housing for engaging a driving mechanism, such as a cam. The second rocker arm housing has a first side plate and a second side plate. The first side plate and the second side plate are spaced apart from each other in a direction of a rotation axis of the second rocker arm housing relative to the first rocker arm housing. The first rocker arm housing is mounted between the first side plate and the second side plate. The valve rocker arm assembly also includes a first roller pair and a second roller pair for jointly engaging the driving mechanism. The first roller pair includes two rollers rotatably coaxially mounted on opposite sides of the first side plate. The second roller pair also includes two rollers rotatably coaxially mounted on opposite sides of the second side plate. The rotation axes of the first roller pair relative to the first side plate and the second roller pair relative to the second side plate are respectively parallel to the rotation axis of the second rocker arm housing relative to the first rocker arm housing. Since the two rollers of each roller pair are located on opposite sides of the corresponding side plate, the loads on both sides of the side plate can be balanced, which is also conducive to smoother and more stable engagement of the drive mechanism (such as a cam). The total axial length of the second rocker arm housing engagement drive mechanism is distributed to the four rollers, so that the dispersed installation space can be more fully utilized. Therefore, it is particularly suitable for situations where there is insufficient external installation space for the rocker arm.

[0006] According to a preferred embodiment of the present invention, the rotation axis of the first roller pair relative to the first side plate can be colinear with the rotation axis of the second roller pair relative to the second side plate. Furthermore, the two rollers of the first roller pair and the two rollers of the second roller pair preferably have the same radius. This facilitates stable and synchronous engagement of the four rollers in the two roller pairs with the drive mechanism.

[0007] According to another preferred embodiment of the present invention, the two rollers of the first roller pair and the two rollers of the second roller pair may have the same axial length. This allows the load to be evenly distributed across the four rollers when the drive mechanism engages the rollers on the second rocker arm housing, thereby facilitating balance and stability of the rocker arm structure.

[0008] According to another preferred embodiment of the present invention, the axial length of each roller of the first roller pair and the second roller pair can be smaller than the axial length of the first roller. This means that the axial length of a single roller on the second rocker arm housing is relatively small, thereby not occupying excessive installation space and avoiding interference with other structures.

[0009] According to another preferred embodiment of the present invention, the first roller pair and the second roller pair can be symmetrically positioned about the first roller in the direction of their rotation axis, so that the driving force acting on the second rocker arm housing is symmetrically distributed about the first roller, thereby facilitating smooth rotation of the second rocker arm housing relative to the first rocker arm housing.

[0010] According to another preferred embodiment of the present invention, the two rollers of the first roller pair can be rotatably mounted on the first side panel via a first common mounting pin passing through the first side panel, and correspondingly, the two rollers of the second roller pair can also be rotatably mounted on the second side panel via a second common mounting pin passing through the second side panel. Particularly preferably, the two rollers of the first roller pair can be symmetrically positioned about the first side panel in the direction of their rotational axis, and correspondingly, the two rollers of the second roller pair can also be symmetrically positioned about the second side panel in the direction of their rotational axis. In other words, the two rollers in the same roller pair can be equidistant from the corresponding side panel. The two rollers in the same roller pair are supported on the corresponding side panel via a common mounting pin, so that the torques acting on both ends of the common mounting pin are approximately the same, which is beneficial to the balance and stability of the rollers on both sides and reduces stress concentration in the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention is further described below with reference to the accompanying drawings. Elements with the same function are represented by the same reference numerals in the drawings.

[0012] Figure 1 A perspective view showing a valve rocker arm assembly according to an embodiment of the present invention; and

[0013] Figure 2 A top view of a valve rocker arm assembly according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0014] The following detailed description and accompanying drawings are used to illustrate the principles of the present invention. The present invention is not limited to the preferred embodiments described. The scope of protection of the present invention is defined by the claims.

[0015] According to an embodiment of the present invention, a valve rocker arm assembly is provided. Figure 1 and Figure 2The figure shows a perspective view and a top view of the valve rocker arm assembly, respectively. This valve rocker arm assembly is used in a valvetrain with switchable valve lift. As shown, the assembly comprises two rocker arm housings: a first rocker arm housing 1 and a second rocker arm housing 2. The first and second rocker arm housings 1 and 2 are each elongated, extending generally longitudinally. They are connected at their respective ends by a cylindrical pivot pin 6, enabling relative rotation about the central axis of the pivot pin 6, which is perpendicular to the longitudinal direction. The second rocker arm housing 2 has two side panels: a first side panel 21 and a second side panel 22. These side panels 21 and 22 are spaced apart along the rotation axis and connected to each other at their respective longitudinal ends. The first rocker arm housing 1 is mounted between the two side panels 21 and 22 of the second rocker arm housing 2. The first rocker arm housing 1 also has two side panels: a third side panel 11 and a fourth side panel 12. A first roller 3 in the form of a roller is rotatably mounted between the third side plate 11 and the fourth side plate 12 in the longitudinal middle portion of the first rocker arm housing 1 (e.g., by a mounting pin, not shown) so as to rollingly engage a drive mechanism (e.g., a cam mechanism, not shown), and the rotation axis of the first roller 3 relative to the first rocker arm housing 1 is parallel to the rotation axis of the second rocker arm housing 2 relative to the first rocker arm housing 1. Preferably, the axial midpoint of the first roller 3 may coincide with the midpoint between the two side plates 11, 12.

[0016] In addition to the first roller 3 mounted on the first rocker arm housing 1, the valve rocker arm assembly also includes two other roller pairs: a first roller pair 4 and a second roller pair 5. The first roller pair 4 includes two rollers in the form of wheels: a second roller 41 and a third roller 42. These two rollers 41, 42 are rotatably mounted on the longitudinal center portion of the first side plate 21 of the second rocker arm housing 2 about a common rotation axis. The rotation axis is parallel to the rotation axis of the second rocker arm housing 2 relative to the first rocker arm housing 1. In the direction of the rotation axis, the second roller 41 and the third roller 42 are respectively located on opposite sides of the first side plate 21. Similarly, the second roller pair 5 also includes two rollers in the form of wheels: a fourth roller 51 and a fifth roller 52. These two rollers 51 and 52 are also rotatably mounted in the longitudinal center portion of the second side plate 22 about a common rotational axis. This rotational axis is colinear with the rotational axis of the first roller pair 4 relative to the first side plate 21. In the direction of this rotational axis, the fourth roller 51 and the fifth roller 52 are respectively located on opposite sides of the second side plate 22. The longitudinal mounting positions of the first and second roller pairs 4 and 5 on the second rocker arm housing 2 substantially correspond to the longitudinal mounting position of the first roller 3 on the first rocker arm housing 1. In other words, during relative rotation of the first and second rocker arm housings 1 and 2, the rotational axes of the first and second roller pairs 4 and 5 relative to the second rocker arm housing 2 and the rotational axis of the first roller 3 relative to the first rocker arm housing 1 can be substantially aligned at a certain rotational position. However, this is not required and the two can also be slightly offset.

[0017] The four rollers in the two roller pairs 4 and 5 all have identical dimensions, specifically, the same axial length and radius, to facilitate joint engagement with the drive mechanism. However, the axial lengths of the four rollers are all less than the axial length of the first roller 3. The two rollers in each roller pair can be rotatably mounted to the corresponding side plate via a common mounting pin extending through the corresponding side plate, wherein the two rollers can independently rotate relative to the common mounting pin, or the two rollers can be fixed to the common mounting pin, which can rotate relative to the corresponding side plate. The two rollers in each roller pair are positioned symmetrically with respect to the side plate located between them in the direction of their rotational axis, specifically at equal distances from the side surfaces of the corresponding side plates. The first roller pair 4 and the second roller pair 5 are also positioned symmetrically with respect to the first rocker arm housing 1 in the direction of their rotational axis, specifically with respect to the first roller 3 mounted on the first rocker arm housing 1.

[0018] The valve rocker arm assembly according to an embodiment of the present invention replaces the two sliding pads on the outer rocker arm in the prior art with two roller pairs to engage the cam mechanism that drives the rocker arm. This converts sliding friction between the outer rocker arm and the cam into rolling friction, thereby significantly reducing wear. Furthermore, the two rollers in each roller pair are supported on opposite sides of the rocker arm side plate via a common mounting pin, so that the torques acting on both ends of the common mounting pin are approximately equal, which promotes balance and stability of the rollers on both sides, thereby reducing stress concentration in the support structure. Furthermore, because the total axial length of the outer rocker arm engaging the cam is distributed among the four rollers, more efficient use can be made of the dispersed installation space, particularly significantly reducing the installation space required on the outer side of the outer rocker arm. This is particularly useful when there is insufficient installation space on the outside of the rocker arm.

[0019] It should be noted that the present invention aims to reduce friction between the valve rocker arm assembly and the drive cam by utilizing additional roller pairs. This technical solution is applicable to various types of switchable valve rocker arms, and is not limited to the specific configuration shown in the above embodiment. For example, in different application scenarios, the longitudinal installation position of each roller may be offset toward the end rather than located in the center; or the specific connection relationship between the two rocker arm housings may vary, such as the push rod connection end of the valve rocker arm can be located on either rocker arm housing. Furthermore, the common mounting pin of the roller pair and the corresponding side plate and roller may be in direct sliding contact, or rolling contact may be provided by needle rollers, and this is not limited by the present invention.

[0020] While the foregoing descriptions illustrate possible embodiments, it should be understood that numerous variations exist through combinations of all known and other technical features and implementations readily conceivable to a skilled artisan. Furthermore, it should be understood that the exemplary embodiments serve merely as examples and in no way limit the scope, application, or configuration of the present invention. The foregoing descriptions are intended primarily to provide a skilled artisan with technical guidance for implementing at least one exemplary embodiment. Various modifications, particularly regarding the functionality and structure of the components described, may be made without departing from the scope of the claims.

[0021] Reference Signs

[0022] 1 First rocker arm housing

[0023] 11 Third side panel

[0024] 12 Fourth side panel

[0025] 2 Second rocker arm housing

[0026] 21 First side panel

[0027] 22 Second side panel

[0028] 3 First roller

[0029] 4 First roller pair

[0030] 41 Second roller

[0031] 42 Third roller

[0032] 5 Second roller pair

[0033] 51 Fourth Roller

[0034] 52 Fifth Roller

[0035] 6 Pivot pin

Claims

1. A valve rocker arm assembly, comprising a first rocker arm housing (1), a second rocker arm housing (2) and a first roller (3), wherein the first rocker arm housing (1) and the second rocker arm housing (2) are rotatably connected to each other, the first roller (3) is rotatably mounted on the first rocker arm housing (1) for engaging a drive mechanism, the second rocker arm housing (2) having a first side plate (21) and a second side plate (22), the first rocker arm housing (1) being mounted between the first side plate (21) and the second side plate (22), It is characterized by: The valve rocker arm assembly further comprises a first roller pair (4) and a second roller pair (5) for jointly engaging the drive mechanism, wherein the first roller pair (4) comprises two rollers (41, 42) rotatably coaxially mounted on opposite sides of the first side plate (21), and the second roller pair (5) comprises two rollers (51, 52) rotatably coaxially mounted on opposite sides of the second side plate (22), and the rotation axis of the first roller pair (4) relative to the first side plate (21) and the rotation axis of the second roller pair (5) relative to the second side plate (22) are respectively parallel to the rotation axis of the second rocker arm housing (2) relative to the first rocker arm housing (1).

2. The valve rocker arm assembly according to claim 1, characterized in that: The rotation axis of the first roller pair (4) relative to the first side plate (21) and the rotation axis of the second roller pair (5) relative to the second side plate (22) are collinear.

3. The valve rocker arm assembly according to claim 2, characterized in that: The two rollers (41, 42) of the first roller pair (4) and the two rollers (51, 52) of the second roller pair (5) have the same radius.

4. The valve rocker arm assembly according to claim 3, characterized in that: The two rollers (41, 42) of the first roller pair (4) and the two rollers (51, 52) of the second roller pair (5) have the same axial length.

5. The valve rocker arm assembly according to claim 4, characterized in that: The axial length of each roller (41, 42, 51, 52) of the first roller pair (4) and the second roller pair (5) is smaller than the axial length of the first roller (3).

6. The valve rocker arm assembly according to claim 3, characterized in that: The first roller pair (4) and the second roller pair (5) are symmetrically positioned with respect to the first roller (3) in the direction of their rotation axes.

7. The valve rocker arm assembly according to any one of claims 1 to 6, characterized in that: The two rollers (41, 42) of the first roller pair (4) are rotatably mounted on the first side plate (21) via a first common mounting pin passing through the first side plate (21), and the two rollers (51, 52) of the second roller pair (5) are rotatably mounted on the second side plate (22) via a second common mounting pin passing through the second side plate (22).

8. The valve rocker arm assembly according to claim 7, characterized in that: The two rollers (41, 42) of the first roller pair (4) are symmetrically positioned about the first side plate (21) in the direction of their rotational axis, and the two rollers (51, 52) of the second roller pair (5) are symmetrically positioned about the second side plate (22) in the direction of their rotational axis.

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