CN214035816U - Rocker arm shaft and rocker arm assembly - Google Patents

Abstract

The application discloses a rocker arm shaft and a rocker arm assembly, wherein the rocker arm shaft comprises a rocker arm shaft body which can extend into a shaft hole of a rocker arm, a main oil duct and at least one group of branch oil ducts are arranged in the rocker arm shaft body, the main oil duct extends along the axial direction of the rocker arm shaft body, and the single group of branch oil ducts comprise a rocker arm shaft head oil duct and a rocker arm shaft tail oil duct with preset included angles; one end of the rocker shaft head oil duct is communicated with the main oil duct, and the other end of the rocker shaft head oil duct extends to the outer surface of the rocker shaft body so as to supply lubricating oil to the rocker shaft head oil duct; one end of the rocker arm shaft tail oil passage is communicated with the main oil passage, and the other end of the rocker arm shaft tail oil passage extends to the outer surface of the rocker arm shaft body so as to supply lubricating oil to the rocker arm tail oil passage. The rocker arm shaft provided by the application can be well lubricated, and the structure of the rocker arm assembly is simplified.

Description

Rocker arm shaft and rocker arm assembly

Technical Field

The application relates to the technical field of valve actuating mechanisms of internal combustion engines, in particular to a rocker arm shaft and a rocker arm assembly.

Background

The working principle of the valve actuating mechanism of the internal combustion engine is as follows: the convex part of the air inlet and exhaust cam of the cam shaft pushes the push rod to do periodic linear reciprocating motion in the rotating process, force and displacement are transmitted to the valve pressing plate through the rocker arm, the air inlet valve and the air exhaust valve are further pushed to be opened, and the valve is reset and closed under the action of the valve spring.

Rocker arm assemblies typically include a rocker arm, a rocker shaft, a rocker bushing, and an adjustment screw, among other things. The wear of the rocker arm mainly comprises the following four parts: the relative motion between the head of the rocker arm and the valve pressing plate is sliding, and a sliding friction pair is arranged; the relative motion of the rocker arm inner hole and the rocker arm shaft is rotation, and a sliding friction pair is arranged between matching surfaces; the tail part of the rocker arm and the concave seat of the push rod move relatively to each other to rotate, and a sliding friction pair is arranged on a contact surface; more than two rocker arms are sleeved on the same rocker arm, the motion rhythm of each rocker arm is asynchronous, the end faces of two adjacent rocker arms are attached to each other and can move relatively, and sliding friction pairs are arranged between the adjacent rocker arms.

In order to ensure good wear resistance of an existing rocker arm assembly, the structure is generally complex, wear-resistant parts are additionally arranged in a friction area, for example, a wear-resistant block is embedded in a head of a rocker arm, and a rocker arm bushing is arranged between a shaft hole of the rocker arm and a rocker arm shaft. The complex structure causes the defects of more parts, high part cost, complex assembly process, reduced product reliability and the like.

In summary, the problem to be solved by those skilled in the art is how to provide a rocker arm assembly with a simple structure and less wear.

SUMMERY OF THE UTILITY MODEL

In view of the above, it is an object of the present invention to provide a rocker arm shaft that can provide good lubricity to a rocker arm and simplify the structure of a rocker arm assembly. It is another object of the present application to provide a rocker arm assembly including the rocker arm shaft described above.

In order to achieve the above purpose, the present application provides the following technical solutions:

a rocker shaft comprising:

the rocker shaft comprises a rocker shaft body which can extend into a shaft hole of a rocker arm, wherein a main oil duct and at least one group of branch oil ducts are arranged in the rocker shaft body, the main oil duct extends along the axial direction of the rocker shaft body, and the single group of branch oil ducts comprise a rocker shaft head oil duct and a rocker shaft tail oil duct which have preset included angles; one end of the rocker shaft head oil duct is communicated with the main oil duct, and the other end of the rocker shaft head oil duct extends to the outer surface of the rocker shaft body so as to supply lubricating oil to the rocker shaft head oil duct; one end of the rocker arm shaft tail oil passage is communicated with the main oil passage, and the other end of the rocker arm shaft tail oil passage extends to the outer surface of the rocker arm shaft body so as to supply lubricating oil to the rocker arm tail oil passage.

Optionally, the rocker shaft further comprises a bottom oil passage, the bottom oil passage is arranged in the middle of the rocker shaft body, the bottom oil passage extends along the radial direction of the rocker shaft body, one end of the bottom oil passage is communicated with the main oil passage, and the other end of the bottom oil passage extends to the outer surface of the rocker shaft body.

Optionally, an axial oil groove is formed in the outer surface of the rocker shaft body, the axial oil groove extends along the axial direction of the rocker shaft body, and the axial oil groove is communicated with the oil outlets of the branch oil ducts.

Optionally, the branch oil passages have three groups, and the axial oil grooves are communicated with oil outlets of the middle group of branch oil passages.

Optionally, the preset included angle is greater than 90 degrees and less than 180 degrees.

Optionally, both ends of the rocker arm shaft body are provided with mounting holes.

Optionally, two ends of the rocker arm shaft body are respectively provided with a mounting hole, and two ends of the main oil gallery respectively extend to the two mounting holes.

Optionally, the branch oil duct further includes a circumferential oil groove formed in the outer surface of the rocker shaft body, the circumferential oil groove extends along the circumferential direction of the rocker shaft body, and the circumferential oil groove is communicated with the oil outlet of the branch oil duct.

Optionally, the middle part of the circumferential oil groove is communicated with the oil outlet of the branch oil passage.

A rocker arm assembly comprising: the rocker arm comprises a rocker arm and any one of the rocker arm shafts, wherein the rocker arm shaft is in clearance fit with a shaft hole of the rocker arm.

Through above-mentioned scheme, the beneficial effect of rocking arm axle and rocking arm assembly that this application provided lies in:

the rocker arm shaft comprises a rocker arm shaft body which can extend into a shaft hole of the rocker arm, a main oil duct and at least one group of branch oil ducts are arranged in the rocker arm shaft body, the main oil duct extends along the axial direction of the rocker arm shaft body, and the single group of branch oil ducts comprise a rocker arm shaft head oil duct and a rocker arm shaft tail oil duct which have preset included angles.

In the working process, lubricating oil in the main oil passage flows to the outer surface of the rocker shaft body through the rocker shaft head oil passage and enters the rocker shaft head oil passage to provide lubricating oil for the friction surface of the rocker head; meanwhile, lubricating oil in the main oil duct flows to the outer surface of the rocker shaft body through the rocker shaft tail oil duct and enters the rocker arm tail oil duct to provide lubricating oil for the friction surface of the rocker arm tail. The lubricating oil fills the gap of each contact pair to generate a lubricating oil film, so that two parts which move relatively are not in direct contact, the supporting force is transmitted through the oil film, the flowing lubricating oil film can continuously take away heat generated by friction, the mechanical property attenuation caused by overheating of the parts is avoided, and the normal work of the rocker arm shaft and the rocker arm is ensured.

The branch oil duct enables the friction pair of the rocker arm to be well lubricated, and abrasion is reduced, so that the rocker arm can omit a wear-resistant insert block in the prior art. In addition, considering that the motion mode of the rocker arm is swinging, the swinging angle is small, and the requirement on the wear resistance is low relative to the rotation motion, the reasonable lubrication mode generates enough oil film thickness to reduce the wear, and the bushing between the rocker shaft hole and the rocker shaft can be omitted under the condition of good lubrication condition and wear resistance.

Therefore, the technical scheme provided by the application realizes the effects of simplifying the structure of the rocker arm assembly, simplifying the assembly process, reducing the cost of parts and improving the reliability of products.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a first perspective view of a rocker arm according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of a second perspective view of a rocker arm according to an embodiment of the present disclosure;

FIG. 3 is a front view of a rocker arm provided in accordance with an embodiment of the present application;

FIG. 4 is a structural diagram of an internal oil passage of a rocker arm according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram illustrating a first perspective view of a rocker shaft according to an embodiment of the present disclosure;

FIG. 6 is a second perspective structural view of a rocker shaft according to an embodiment of the present disclosure;

FIG. 7 is a block diagram of an internal oil gallery of a rocker arm shaft according to an embodiment of the present disclosure;

FIG. 8 is a block diagram of a rocker arm assembly according to an embodiment of the present disclosure.

The reference numbers in the figures are: the rocker arm comprises a rocker arm 1, a rocker arm body 11, a rocker arm head 111, a rocker arm middle part 112, a rocker arm tail 113, a shaft hole 12, a rocker arm head friction surface 13, a rocker arm tail friction surface 14, a rocker arm head oil passage 15, a rocker arm head first oil passage 151, a rocker arm head second oil passage 152 and a rocker arm tail oil passage 16; rocker shaft 2, rocker shaft body 21, main oil gallery 22, branch oil gallery 23, rocker shaft head oil gallery 231, rocker shaft tail oil gallery 232, circumferential oil groove 233, bottom oil gallery 24, axial oil groove 25 and mounting hole 26; push rod 3, valve pressing plate 4, valve 5.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 1 to 4, the rocker arm 1 provided by the present application may be an intake rocker arm, an exhaust rocker arm, or an injector rocker arm, the rocker arm 1 includes a rocker arm body 11, the rocker arm body 11 is provided with a shaft hole 12, the rocker arm body 11 is provided with a rocker arm head friction surface 13 and a rocker arm tail friction surface 14, and a rocker arm head oil passage 15 and a rocker arm tail oil passage 16 are provided inside the rocker arm body 11.

Specifically, rocker arm body 11 includes rocker arm head 111, rocker arm middle part 112 and rocker arm tail 113, and rocker arm middle part 112 is located the centre of rocker arm head 111 and rocker arm tail 113, and rocker arm body 11 formula structure as an organic whole specifically indicates: the rocker arm head 111, the rocker arm middle part 112 and the rocker arm tail part 113 are of an integrated structure and are made of the same material.

The shaft hole 12 is arranged in the middle of the rocker arm body 11, and the rocker arm body 11 is sleeved on the periphery of the rocker arm shaft 2 through the shaft hole 12.

The friction surface refers to a surface which is in contact with other components on the rocker arm 1 and has relative displacement; the rocker arm head friction surface 13 is used for being in sliding fit with the valve pressure plate 4, and the rocker arm head friction surface 13 is specifically arranged on the rocker arm head 111; the rocker arm tail friction surface 14 is used for being matched with the push rod 3 in a sliding mode, and the rocker arm tail friction surface 14 is arranged on the rocker arm tail 113.

The rocker head oil passage 15 extends from the shaft hole 12 to the rocker head frictional surface 13 so that the lubricating oil can flow from the shaft hole 12 to the rocker head frictional surface 13; the rocker arm tail oil passage 16 extends from the shaft hole 12 to the rocker arm tail friction surface 14 so that lubricating oil can flow from the shaft hole 12 to the rocker arm tail friction surface 14.

The rocker arm 1 with the structure has the beneficial effects that: the rocker arm shaft has a good lubricating effect, adopts an integrated structure, does not need to arrange a bushing in the shaft hole 12 of the rocker arm shaft 2, does not need to arrange a wear-resistant insert, and has the advantages of simple structure, convenience in assembly and lower cost.

Alternatively, in one embodiment, the axis of the rocker arm head oil passage 15 and the axis of the rocker arm tail oil passage 16 intersect at a point inside the shaft hole 12. Specifically, the rocker arm head oil passage 15 and the rocker arm tail oil passage 16 intersect in the axis, which means that the two oil passages are coplanar and are convenient to match with the oil outlet hole on the rocker arm shaft 2.

Optionally, in one embodiment, the rocker arm head friction surface 13 is a circular arc surface. Specifically, the relative sliding direction between the rocker arm 1 and the valve pressure plate 4 is always tangent to the friction surface of the rocker arm head 111, so that the friction resistance can be reduced.

Alternatively, to improve the wear resistance of the rocker arm body 11, the friction surface may be heat treated, for example, by applying a suitable heat treatment process to the rocker arm head friction surface 13 after machining.

Alternatively, in one embodiment, the rocker arm head friction surface 13 is a bottom surface of the rocker arm head 111 that can push the valve pressure plate 4 downward; accordingly, the rocker head oil passage 15 includes a rocker head first oil passage 151 and a rocker head second oil passage 152, the rocker head first oil passage 151 extends from the shaft hole 12 to a side end surface of the rocker head 111 of the rocker arm body 11, an upper end of the rocker head second oil passage 152 communicates with a middle region of the rocker head first oil passage 151, and a lower end of the rocker head second oil passage 152 extends to a bottom surface of the rocker head 111. Specifically, in the rocker arm head oil passage 15 having such a structure, the rocker arm head second oil passage 152 directly supplies lubricating oil to the rocker arm head friction surface 13 during operation, and the rocker arm head first oil passage 151 can discharge excess lubricating oil, considering that the lubricating oil in the oil passages has a certain oil pressure.

Optionally, in an embodiment, the rocker arm body 11 is provided with a rocker arm tail through hole, and the rocker arm tail friction surface 14 is an inner side wall of the rocker arm tail through hole. Specifically, the periphery of push rod 3 is located through rocking arm afterbody through-hole cover to rocking arm body 11, and push rod 3 can retrain the rotation direction of rocking arm 1, plays limiting displacement.

Alternatively, in one embodiment, the rocker arm tail oil passage 16 extends from the shaft hole 12 to the outer surface of the rocker arm body 11, and the middle portion of the rocker arm tail oil passage 16 passes through the rocker arm tail through hole. Specifically, at this time, the rocker arm tail oil passage 16 is divided into two parts by the shaft hole 12, the two parts are a rocker arm tail first oil passage and a rocker arm tail second oil passage respectively, axes of the two parts are collinear, the rocker arm tail first oil passage extends from the shaft hole 12 to the rocker arm tail through hole, the rocker arm tail second oil passage extends from the rocker arm tail through hole to the side end face of the rocker arm tail 113, and the rocker arm tail second oil passage can discharge redundant lubricating oil.

Optionally, in an embodiment, the inner side wall of the shaft hole 12 is provided with a mesh structure and matched with a suitable roughness, the mesh structure is provided with a plurality of fine pits, so that a lubricating oil film is formed conveniently, oil can be stored, the friction coefficient is reduced, and dry friction is avoided.

Optionally, in an embodiment, an end surface of the shaft hole 12 protrudes from a surface of the rocker arm body 11, when a plurality of rocker arms 1 are sleeved outside the same rocker arm shaft 2, end surfaces of the shaft holes 12 of adjacent rocker arms 1 contact and rub, at this time, the lubricating oil in the shaft holes 12 may directly flow out along a gap between the shaft hole 12 and the rocker arm shaft 2, and the gap between the end surfaces of the shaft holes 12 of adjacent rocker arms 1 is filled to lubricate the end surfaces of the rocker arms 1.

Referring to fig. 5 to 7, the rocker arm shaft 2 provided by the present application includes a rocker arm shaft body 21, the rocker arm shaft body 21 can extend into the shaft hole 12 of the rocker arm 1, the rocker arm shaft body 21 is provided therein with a main oil passage 22 and at least one set of branch oil passages 23, and the number of the sets of branch oil passages 23 may be consistent with the number of the rocker arms 1 provided on a single rocker arm shaft 2. The main oil gallery 22 extends in the axial direction of the rocker shaft body 21.

The single group of branch oil passage 23 includes two radial oil passages, which are a rocker shaft head oil passage 231 and a rocker shaft tail oil passage 232, respectively, both of which extend in the radial direction of the rocker shaft body 21 and have a predetermined included angle. In addition, one end of the rocker shaft head oil passage 231 is communicated with the main oil passage 22, and the other end extends to the outer surface of the rocker shaft body 21 and corresponds to the rocker arm head oil passage 15, so that lubricating oil is provided for the rocker arm head oil passage 15, and the lubricating oil lubricates a friction pair between the rocker arm 1 and the valve pressure plate 4; the rocker arm shaft tail oil passage 232 has one end communicating with the main oil passage 22 and the other end extending to the outer surface of the rocker arm shaft body 21 and corresponding to the rocker arm tail oil passage 16 so as to supply lubricating oil to the rocker arm tail oil passage 16 so that the lubricating oil lubricates the friction pair between the rocker arm 1 and the pushrod 3.

In the working process of the rocker arm shaft 2 with the structure, lubricating oil from a lubricating system of an internal combustion engine firstly flows into the main oil passage 22 and respectively enters the rocker arm shaft head oil passage 231 and the rocker arm tail oil passage 16 under the action of oil pressure, so that the rocker arm 1 is well lubricated, and the abrasion of the rocker arm 1 is avoided.

Optionally, in an embodiment, the rocker shaft 2 further includes an axial oil groove 25, the axial oil groove 25 is disposed on an outer surface of the rocker shaft body 21 and extends in an axial direction of the rocker shaft body 21, and the axial oil groove 25 is communicated with the oil outlet of the branch oil passage 23. Specifically, the axial oil groove 25 ensures that the oil film thickness in the width direction is uniformly distributed. In addition, when a plurality of rocker arms 1 are sleeved outside the same rocker arm shaft 2, and the length of the axial oil groove 25 is greater than the thickness of a single rocker arm 1, the axial oil groove 25 can also lubricate gaps between end faces of adjacent rocker arms 1.

Optionally, in an embodiment, there are three sets of branch oil passages 23, the axial oil grooves 25 are communicated with oil outlets of the middle set of branch oil passages 23, the oil outlets refer to intersection positions of the radial oil passages and the outer surface of the rocker shaft body 21, and the axial oil grooves 25 may be communicated with any one of the radial oil passages. For the case that three rocker arms 1 are arranged on the rocker arm shaft 2, the rocker arms 1 on the two sides are respectively an intake rocker arm and an exhaust rocker arm, the rocker arm 1 in the middle is an oil injector rocker arm, and because the load of the rocker arm 1 in the middle is larger, the axial oil groove 25 can be arranged on the branch oil passage 23 in the middle, so that the lubricating effect in the middle of the rocker arm shaft 2 is improved.

Optionally, in an embodiment, the rocker arm shaft 2 further includes a bottom oil passage 24, the bottom oil passage 24 extends in a radial direction of the rocker arm shaft body 21, and one end of the bottom oil passage 24 is communicated with the main oil passage 22, and the other end extends to the outer surface of the rocker arm shaft body 21. Specifically, the lubricating oil of the bottom oil gallery 24 fills the gap between the rocker arm shaft 2 and the shaft hole 12 of the rocker arm 1. In addition, in view of the greater load on the middle portion of the rocker shaft 2, it is preferable that the bottom oil gallery 24 be provided in the middle portion of the rocker shaft body 21 to further improve the lubricating effect on the middle portion of the rocker shaft 2.

Optionally, in an embodiment, considering that the friction surface 13 of the head of the rocker arm and the friction surface 14 of the tail of the rocker arm are distributed at two ends of the rocker arm 1, the preset included angle is an obtuse angle, and the preset included angle is greater than 90 degrees and less than 180 degrees, so that the lubricating oil can more conveniently enter the oil passage of the rocker arm 1 from the oil passage of the rocker arm shaft 2.

Optionally, in one embodiment, the rocker shaft body 21 is provided with mounting holes 26 at both ends. Specifically, when mounting, two mounting holes 26 each pass through one mounting shaft, thereby fixing the rocker shaft body 21.

Alternatively, in one embodiment, the rocker shaft body 21 is provided with one mounting hole 26 at each of the two ends, and the main oil gallery 22 extends to the two mounting holes 26 at each of the two ends. Specifically, the mounting hole 26 may serve as an oil inlet of the main oil gallery 22. In practical applications, one of the mounting holes 26 may be used as an oil inlet of the main oil gallery 22, and the other mounting hole 26 may be closed.

Optionally, in an embodiment, the branch oil passage 23 further includes a circumferential oil groove 233, the circumferential oil groove 233 is disposed on an outer surface of the rocker shaft body 21 and extends in a circumferential direction of the rocker shaft body 21, the circumferential oil groove 233 is communicated with an oil outlet of the branch oil passage 23, and the circumferential oil groove 233 may be communicated with any one of the radial oil passages. Specifically, the circumferential oil groove 233 ensures that the lubricating oil can enter the oil passage inside the rocker arm 1 at a low flow resistance within the range of the swing angle of the rocker arm 1.

Optionally, in an embodiment, in consideration that the rocker arm 1 needs to swing up and down around the rocker arm shaft 2, in order to ensure that lubricating oil can enter the oil passage of the rocker arm 1 from the oil passage of the rocker arm shaft 2 in the process of swinging up and down of the rocker arm 1, the middle part of the circumferential oil groove 233 is communicated with the oil outlet of the branch oil passage 23, that is, the circumferential oil grooves 233 are distributed on both circumferential sides of the oil outlet of the branch oil passage 23. It is understood that the branch oil passage 23 may be any one of the radial oil passages. Preferably, the oil outlet of each radial oil passage is provided with a circumferential oil groove 233.

Optionally, in an embodiment, the outer surface of the rocker arm shaft 2 is a heat treated surface, and after the outer surface of the rocker arm shaft 2 is machined, the heat treatment is adopted to improve the surface wear resistance.

During actual design, the GT-Suite is used for analyzing a lubricating oil film, the most reasonable matching clearance between the rocker arm shaft 2 and the rocker arm 1 is calculated, the hole diameter and tolerance of the shaft hole 12 of the rocker arm 1 are determined, the outer diameter and tolerance of the rocker arm shaft 2 are determined, and a reasonable lubricating oil channel arrangement scheme is obtained. Stress distribution conditions of the rocker arm 1 and the rocker arm shaft 2 can be obtained through Ansys analysis, and a lightweight design structure is obtained on the premise that the requirements for fatigue strength and rigidity are met.

Referring to fig. 8, the present application further provides a rocker arm assembly, which includes a rocker arm 1 and a rocker shaft 2, wherein the rocker arm 1 may be any one of the rocker arms 1, the rocker shaft 2 may be any one of the rocker arms 2, the rocker shaft 2 is in clearance fit with the shaft hole 12 of the rocker arm 1, and no bushing is disposed therebetween.

Optionally, the rocker arm assembly may further include a cam, a push rod 3, and a valve pressing plate 4, an outer contour of the cam is attached to a lower end of the push rod 3, an upper end of the push rod 3 is matched with a rocker arm tail friction surface 14 of the rocker arm 1, and the valve pressing plate 4 is matched with a rocker arm head friction surface 13 of the rocker arm 1. In the working process, the cam rotates and pushes the push rod 3 to do periodic linear reciprocating motion, force and displacement are transmitted to the valve pressing plate 4 through the rocker arm 1, the valve 5 is further pushed to be opened, and the valve 5 is reset and closed under the action of the valve spring.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The rocker arm shaft and rocker arm assembly provided herein have been described in detail above. The principles and embodiments of the present application are explained herein using specific examples, which are provided only to help understand the method and the core idea of the present application. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.

Claims (10)

1. Rocker arm shaft (2), characterized in that it comprises:

the rocker shaft comprises a rocker shaft body (21) capable of extending into a shaft hole (12) of a rocker arm (1), wherein a main oil duct (22) and at least one group of branch oil ducts (23) are arranged inside the rocker shaft body (21), the main oil duct (22) extends along the axial direction of the rocker shaft body (21), and a single group of branch oil ducts (23) comprise a rocker shaft head oil duct (231) with a preset included angle and a rocker shaft tail oil duct (232); one end of the rocker arm shaft head oil passage (231) is communicated with the main oil passage (22), and the other end of the rocker arm shaft head oil passage extends to the outer surface of the rocker arm shaft body (21) so as to supply lubricating oil to the rocker arm head oil passage (15); one end of the rocker arm shaft tail oil passage (232) is communicated with the main oil passage (22), and the other end of the rocker arm shaft tail oil passage extends to the outer surface of the rocker arm shaft body (21) to supply lubricating oil to the rocker arm tail oil passage (16).

2. The rocker arm shaft (2) of claim 1, further comprising a bottom oil passage (24), wherein the bottom oil passage (24) is formed in the middle of the rocker arm shaft body (21), the bottom oil passage (24) extends in the radial direction of the rocker arm shaft body (21), one end of the bottom oil passage (24) is communicated with the main oil passage (22), and the other end of the bottom oil passage extends to the outer surface of the rocker arm shaft body (21).

3. The rocker shaft (2) of claim 1, wherein the outer surface of the rocker shaft body (21) is provided with an axial oil groove (25), the axial oil groove (25) extending in the axial direction of the rocker shaft body (21), the axial oil groove (25) communicating with the oil outlet of the branch oil passage (23).

4. The rocker shaft (2) of claim 3, wherein there are three sets of branch oil passages (23), and the axial oil grooves (25) communicate with oil outlets of the middle set of branch oil passages (23).

5. The rocker shaft (2) of claim 1, in which the predetermined included angle is greater than 90 degrees and less than 180 degrees.

6. The rocker shaft (2) of claim 1, in which the rocker shaft body (21) is provided with mounting holes (26) at both ends.

7. The rocker shaft (2) of claim 6, in which the rocker shaft body (21) is provided with one mounting hole (26) at each end, and the main oil gallery (22) extends to two of the mounting holes (26) at each end.

8. The rocker shaft (2) of any one of claims 1 to 7, wherein the branch oil passage (23) further comprises a circumferential oil groove (233) provided in the outer surface of the rocker shaft body (21), the circumferential oil groove (233) extending in the circumferential direction of the rocker shaft body (21), the circumferential oil groove (233) communicating with an oil outlet of the branch oil passage (23).

9. The rocker shaft (2) of claim 8, wherein the middle of the circumferential oil groove (233) communicates with the oil outlet of the branch oil passage (23).

10. A rocker arm assembly, comprising a rocker arm (1) and a rocker arm shaft (2) according to any of claims 1 to 9, the rocker arm shaft (2) being clearance-fitted in a shaft bore (12) of the rocker arm (1).

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