A composite roller rocker arm assembly

Abstract

A composite roller type rocker arm assembly relates to an engine valve rocker arm assembly. The camshaft and the rocker arm shaft are installed on the engine cylinder head through the support and the bolt, the cam part of the camshaft is in contact with the outer roller of the rocker arm, the rocker arm is installed on the rocker arm shaft through the clearance fit, and the rocker arm is rotatably connected with the rocker arm shaft; the roller pin shaft is fixedly installed on the rocker arm through the press-fit interference fit, the inner roller and the outer roller are positioned and installed on the roller pin shaft through the roller groove end face of the rocker arm, the inner roller is installed on the roller pin shaft, and the outer roller is installed on the outer side of the inner roller. The utility model can effectively reduce the contact stress between the outer roller and the cam part, reduce the risk of damage of parts due to excessive contact stress, improve the contact reliability and durability, prolong the service life of the rocker arm assembly and the whole mechanical equipment, reduce the maintenance cost and downtime of the equipment, improve the working performance of the internal combustion engine and other mechanical equipment, make the operation more stable and efficient, and greatly reduce the material cost.

Description

Technical Field

[0001] This utility model relates to the technical field of engine valve rocker arm assembly, specifically a composite roller type rocker arm assembly. Background Technology

[0002] Roller-type rocker arm assemblies are commonly used units in the valve train of internal combustion engines. They primarily achieve the opening and closing of valves by the rolling contact between rollers and camshafts, thereby controlling the intake and exhaust processes of the internal combustion engine and achieving optimal performance. While alcohol-hydrogen fuel engines are cleaner and more environmentally friendly than gasoline engines, traditional roller-type rocker arm assemblies present several problems in practical applications. Due to their single-roller structure, using a manganese brass roller shaft and a GCr15 roller body, these rollers frequently experience impact and corrosion fatigue when applied to alcohol-hydrogen fuel engines, leading to premature roller failure. This is mainly because alcohol-hydrogen fuels produce small amounts of acidic corrosive gases during combustion. Combined with the high temperature and power impact of the engine, this easily causes impact and corrosion fatigue in the rollers and roller shafts, accelerating wear, pitting, and spalling of parts, resulting in premature engine failure. Summary of the Invention

[0003] To address the shortcomings of existing roller rocker arm assemblies, the present invention aims to provide a composite roller rocker arm assembly. By improving the materials, structure, and lubrication of the components, this invention effectively solves the problem of premature roller failure caused by roller corrosion, fatigue, and wear in the prior art.

[0004] To achieve the above-mentioned objectives, the present invention discloses a composite roller rocker arm assembly in which the camshaft and rocker arm shaft are mounted on the engine cylinder head via a support and bolts. The cam component of the camshaft contacts the outer roller of the rocker arm. The rocker arm is mounted on the rocker arm shaft with a clearance fit, and the rocker arm and rocker arm shaft are rotatably connected. The roller pin is fixedly mounted on the rocker arm with a press-fit interference fit. The inner roller and outer roller are positioned on the roller pin through the roller groove end face of the rocker arm. The inner roller is mounted on the roller pin, and the outer roller is mounted on the outside of the inner roller.

[0005] Furthermore, the inner roller is press-fitted onto the roller pin with a clearance fit, and the clearance between the inner roller and the roller pin is 0.03 to 0.05 mm.

[0006] Furthermore, the outer roller is press-fitted onto the outside of the inner roller with a clearance fit, and the clearance between the outer roller and the inner roller is 0.035 to 0.055 mm.

[0007] Furthermore, the surface of the inner roller is coated with a DLC coating, the grade of which is DLC-A. The inner roller is made of 40Cr material and has undergone tempering and nitriding treatment. The inner roller is equipped with dual oil channels.

[0008] Furthermore, the outer roller has a drum-shaped outer surface, which is a circular arc structure with a convex middle and slightly tapered ends. The height difference h of the convex middle is 0.008mm, the radius of curvature R of the middle is 0.0625mm, and the radius of curvature R1 of the ends is 0.044mm.

[0009] Furthermore, the rocker arm shaft has a hollow structure, and a lubricating oil hole is provided in the middle of the bottom of the roller groove.

[0010] Furthermore, the lubricating oil hole is connected to the lubricating oil hole on the rocker arm shaft, and the center line of the lubricating oil hole on the rocker arm shaft is concentric with the center line of the lubricating oil hole on the roller groove.

[0011] Furthermore, the roller pin is made of 20Cr material and is manufactured through nitrocarburizing treatment, and the roller pin is provided with symmetrical multi-oil channels.

[0012] Furthermore, a valve adjusting screw is installed on the threaded hole of the rocker arm. The elephant foot and the ball head of the valve adjusting screw are connected by a shrinkage joint riveting. After riveting, the bowl of the elephant foot and the neck of the screw are connected by a hinged rivet. An annular oil groove is designed in the middle of the valve adjusting screw. The annular oil groove is connected to the transverse oil passage and the straight oil passage in the valve adjusting screw. The annular oil groove is also connected to the oil passage of the rocker arm body. A nut is installed on the valve adjusting screw.

[0013] Compared with the prior art, this utility model has the following advantages: 1. Reduced contact stress: Through the unique double roller structure design, especially the drum-shaped outer surface design of the outer roller, point contact between the outer roller and the cam component is effectively avoided, the contact stress is dispersed, the contact stress is greatly reduced, and the risk of damage to parts due to excessive contact stress is reduced.

[0014] 2. Improved contact reliability and durability: Good contact condition makes the movement between the outer roller and the cam component smoother and more reliable, reduces abnormal wear and failure, significantly improves the contact reliability and durability between the two, extends the service life of the rocker arm assembly and the entire mechanical equipment, and reduces equipment maintenance costs and downtime.

[0015] 3. Improve mechanical performance: A stable and reliable rocker arm assembly mechanism can ensure the normal operation of components such as valves, thereby improving the working performance of mechanical equipment such as internal combustion engines, making them run more stably and efficiently.

[0016] 4. Reduced manufacturing costs: Traditional rocker arm pins are made of manganese brass alloy, which is expensive. Once the roller and cam make point contact, the contact stress is large and the wear is fast. The roller pin of this utility model is made of alloy steel with surface carburizing treatment, which not only improves the wear resistance of the parts, but also greatly reduces the material cost. Attached Figure Description

[0017] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram of the rocker arm drive mechanism of this utility model.

[0018] Figure 2 yes Figure 1 Side view.

[0019] Figure 3 yes Figure 1 A cross-sectional view of the double roller rocker arm structure.

[0020] Figure 4 yes Figure 1 A schematic diagram showing the contact between the rocker arm roller and the cam component of the camshaft.

[0021] Figure 5 This is an enlarged schematic diagram of the outer roller drum-shaped structure.

[0022] Figure 6 yes Figure 5 A cross-sectional view of the elephant foot structure of the rocker arm.

[0023] Figure 7 for Figure 6 AA sectional view.

[0024] Figure 8 for Figure 6 BB cross-sectional view.

[0025] In the diagram: 1. Camshaft; 2. Rocker arm; 3. Rocker arm shaft; 4. Outer roller; 5. Inner roller; 6. Pin; 7. Roller groove; 8. Lubricating oil hole; 9. Multiple oil passages; 10. Double oil passages; 11. Valve adjusting screw; 12. Valve adjusting screw ball head; 13. Elephant foot; 14. Threaded hole; 15. Bowl mouth; 16. Screw neck; 17. Annular oil groove; 18. Transverse oil passage; 19. Straight oil passage; 20. Nut; 21. Rocker arm body oil passage. Detailed Implementation

[0026] To make the invention's objectives, technical solutions, and advantages clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the scope of protection of the present invention.

[0027] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, in this utility model, the camshaft 1 and rocker arm shaft 3 of the rocker arm drive mechanism of a composite roller rocker arm assembly are mounted on the engine cylinder head by a support and bolts. The cam component of the camshaft 1 contacts the outer roller 4 of the rocker arm 2. The rocker arm 2 is mounted on the rocker arm shaft 3 by clearance fit, and the rocker arm 2 and the rocker arm shaft 3 are rotatably connected. The roller pin 6 is fixedly mounted on the rocker arm 2 by press-fit interference fit. The inner roller 5 and the outer roller 4 are positioned on the roller pin 6 by the end face of the roller groove 7 of the rocker arm 2. The inner roller 5 is mounted on the roller pin 6, and the outer roller 4 is mounted on the outside of the inner roller 5. The inner roller 5 and the roller pin 6, and the inner roller 5 and the outer roller 4 can rotate flexibly.

[0028] Preferably, the inner roller 5 is press-fitted onto the roller pin 6 with a clearance fit. The clearance between the inner roller 5 and the roller pin 6 is 0.03–0.05 mm to ensure that the inner roller 5 can rotate flexibly on the roller pin 6. The surface of the inner roller 5 is coated with a DLC coating, the grade of which is DLC-A. The DLC coating combines the high hardness of diamond with the lubricity of graphite. It is an amorphous coating film composed of carbon and hydrogen. The DLC coating is mainly synthesized using PVD or PACVD processes at a temperature of 100℃–300℃. It has advantages such as high hardness, good wear resistance, strong corrosion resistance, low coefficient of friction, and excellent lubrication performance, and also has characteristics such as electrical insulation, chemical stability, and light transmittance. The inner roller 5 is made of 40Cr material and undergoes a composite treatment process of tempering, nitriding, and DLC coating. At the same time, the inner roller 5 is also designed with double oil passages 10, which are connected to the multiple oil passages 9 on the roller pin 6, which can ensure good lubrication between the inner surface of the inner roller 5 and the roller pin 6, and between the outer surface of the inner roller 5 and the contact surface of the outer roller 4.

[0029] Preferably, the outer roller 4 is press-fitted onto the outside of the inner roller 5 with a clearance fit. The clearance between the outer roller 4 and the inner roller 5 is 0.035 to 0.055 mm. The outer roller 4 is made of 20CrMnTi material and is carburized to ensure high surface hardness and high wear resistance. At the same time, the core has good toughness and can ensure good contact fatigue.

[0030] Preferably, the outer roller 4 has a drum-shaped outer surface, which is a circular arc structure with a convex center and slightly tapered ends. The height difference h of the convex center is 0.008 mm, the radius of curvature R of the center is 0.0625 mm, and the radius of curvature R1 of the ends is 0.044 mm. The main significance of designing the outer roller 4 as a drum shape is reflected in the following aspects: (a) Adaptive compensation for rocker arm swing offset and correction of contact line offset The contact line between the outer roller 4 and the cam component will shift axially due to changes in angle (especially under large swing angle conditions). The drum-shaped profile of the outer roller 4 (large curvature in the middle and small curvature at both ends) ensures that the contact line between it and the cam component is always kept in the middle of the outer roller 4, avoiding excessive wear at the edges.

[0031] (b) Reduce edge stress concentration If the axial width of a regular arc-shaped roller is large, an "edge effect" (excessive local stress) is likely to occur during edge contact, resulting in uneven contact pressure distribution. The drum-shaped outer surface design of the outer roller 4, with its high center and low ends, allows the contact pressure to be distributed in a parabolic pattern of "high center - low ends," reducing the risk of edge wear.

[0032] (c) Adapting to cam axial tolerance: When there is a small axial runout or installation deviation in the camshaft 1, the drum-shaped outer roller 4 can adaptively adjust the contact area through the curved surface to avoid local overload.

[0033] (d) Optimize lubrication and heat dissipation When the drum-shaped surface of the outer roller 4 contacts the cam component, the raised part in the middle can squeeze the lubricating oil to form a "wedge-shaped oil film" during the rolling process, which strengthens the oil wedge effect. Compared with a flat surface or ordinary arc, the oil film thickness increases by about 30%, which can effectively improve the anti-wear performance, especially under cold start or high load conditions.

[0034] (e) Optimized heat dissipation area: The curved surface transition of the outer roller 4 drum-shaped profile is smoother, which can reduce the accumulation of frictional heat. Combined with the surface DLC coating of the inner roller 5, the temperature can be further reduced.

[0035] Preferably, the rocker arm shaft 3 is a hollow structure, and a roller groove 7 is provided between the outer roller 4 and the rocker arm 2. A lubricating oil hole 8 with a diameter of φ0.7 is designed in the middle of the bottom of the roller groove 7 to ensure good lubrication between the outer roller 4 and the cam component. The lubricating oil hole 8 is connected to the lubricating oil hole on the rocker arm shaft 3, and the center line of the lubricating oil hole on the rocker arm shaft 3 is concentric with the center line of the lubricating oil hole 8 on the roller groove 7.

[0036] Preferably, the roller pin 6 is made of 20Cr material and is manufactured through nitrocarburizing treatment. The roller pin 6 is provided with symmetrical multiple oil passages 9. The roller pin 6 has the characteristics of high hardness, high wear resistance, high resistance to formic acid gas corrosion and low coefficient of friction. The structural design of the multiple oil passages 9 on the roller pin 6 can better ensure the instantaneous and complete establishment of the lubricating oil film, ensure good lubrication of the mating surface between the roller pin 6 and the inner roller 5, and effectively reduce the corrosion and wear of parts.

[0037] Preferably, a valve adjusting screw 11 is mounted on the threaded hole 14 of the rocker arm 2. The foot 13 and the valve adjusting screw ball head 12 of the valve adjusting screw 11 are connected by a constriction joint riveting. After riveting, the bowl 15 of the foot 13 and the screw neck 16 form a hinged riveting lock. The valve adjusting screw 11 is made of 42CrMo material with quenching and tempering treatment and induction hardening of the ball head surface, so that the strength grade of the stem of the valve adjusting screw 11 can reach 12.9 grade, and the spherical surface hardness of the valve adjusting screw ball head 12 can reach 56HRC~60HRC to ensure valve adjustment. The screw 11 and the ball head 12 of the valve adjusting screw have high wear resistance; the valve adjusting screw 11 has an annular oil groove 17 in the middle, which is connected to the transverse oil passage 18 and the straight oil passage 19 inside the valve adjusting screw 11. The annular oil groove 17 is also connected to the rocker arm body oil passage 21; the nut 20 is installed on the other end of the valve adjusting screw 11 and is locked to the end face of the threaded hole 14 of the rocker arm body 2 by screwing. The elephant foot 13 can rotate 360° around the axis of the valve adjusting screw 11. When working, the valve adjusting screw 11 does not rotate, and the elephant foot 13 can move flexibly at multiple angles.

[0038] When the camshaft 1 rotates, the cam assembly rotates accordingly. Since the cam assembly is in contact with the outer surface of the outer roller 4, the rotational motion of the camshaft 1 is transmitted to the rocker arm assembly through the outer roller 4. During this process, the inner roller 5, which is mounted on the pin 6, can rotate freely, while the pin 6 is fixed on the rocker arm 2. At the same time, the surface of the inner roller 5 is coated with DLC coating, which has the characteristics of high hardness, good wear resistance, strong corrosion resistance, and low coefficient of friction, which can effectively reduce the corrosion and wear of parts. Meanwhile, the outer roller 4 can rotate on the outer surface of the inner roller 5. This double roller structure design increases the contact area between the inner roller 5 and the rocker arm 2. Meanwhile, the drum-shaped outer surface structure of the outer roller 4 ensures that even when the rocker arm assembly tilts slightly, the outer roller 4 and the camshaft 1 can still maintain good contact, avoiding point contact and reducing contact stress. This ensures that the rocker arm assembly can stably transmit the cam's motion to components such as valves, achieving normal mechanical motion and force transmission. This effectively solves the problem of early failure of the rocker arm assembly's rollers due to impact, corrosion, and fatigue under the special operating conditions of "ethanol-hydrogen fuel" new energy engines.

[0039] The above description is merely a preferred embodiment of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model. Structures, devices, and operating methods not specifically described or explained in this utility model, unless otherwise specified or limited, shall be implemented using conventional methods in the field.

Claims

1. A composite roller rocker arm assembly, wherein a camshaft (1) and a rocker arm shaft (3) are mounted on an engine cylinder head via supports and bolts, characterized in that: The cam portion of the camshaft (1) contacts the outer roller (4) of the rocker arm (2). The rocker arm (2) is mounted on the rocker arm shaft (3) with clearance fit. The rocker arm (2) and the rocker arm shaft (3) are rotatably connected. The roller pin (6) is fixedly mounted on the rocker arm (2) with press-fit interference fit. The inner roller (5) and the outer roller (4) are positioned on the roller pin (6) through the end face of the roller groove (7) of the rocker arm (2). The inner roller (5) is mounted on the roller pin (6), and the outer roller (4) is mounted on the outside of the inner roller (5).

2. The composite roller rocker arm assembly according to claim 1, characterized in that: The inner roller (5) is press-fitted onto the roller pin (6) with a clearance fit, and the clearance between the inner roller (5) and the roller pin (6) is 0.03 to 0.05 mm.

3. The composite roller rocker arm assembly according to claim 1, characterized in that: The outer roller (4) is press-fitted onto the outside of the inner roller (5) with a clearance fit, and the clearance between the outer roller (4) and the inner roller (5) is 0.035 to 0.055 mm.

4. The composite roller rocker arm assembly according to claim 1, characterized in that: The inner roller (5) is coated with DLC coating, the grade of which is DLC-A. The inner roller (5) is made of 40Cr material and is subjected to tempering and nitriding treatment. The inner roller (5) is provided with double oil passages (10).

5. A composite roller rocker arm assembly according to claim 1, characterized in that: The outer roller (4) has a drum-shaped outer surface, which is a circular arc structure with a raised middle and slightly tapered ends. The height difference h of the raised middle is 0.008mm, the radius of curvature R in the middle is 0.0625mm, and the radius of curvature R1 at both ends is 0.044mm.

6. A composite roller rocker arm assembly according to claim 1, characterized in that: The rocker arm shaft (3) is a hollow structure, and a lubricating oil hole (8) is provided in the middle of the bottom of the roller groove (7).

7. A composite roller rocker arm assembly according to claim 6, characterized in that: The lubricating oil hole (8) is connected to the lubricating oil hole on the rocker arm shaft (3), and the center line of the lubricating oil hole on the rocker arm shaft (3) is concentric with the center line of the lubricating oil hole (8) on the roller groove (7).

8. A composite roller rocker arm assembly according to claim 1, characterized in that: The roller pin (6) is made of 20Cr material and is treated with nitrocarburizing. The roller pin (6) is provided with symmetrical multi-oil channels (9).

9. A composite roller rocker arm assembly according to claim 1, characterized in that: The rocker arm (2) has a threaded hole (14) fitted with a valve adjusting screw (11). The elephant foot (13) and the valve adjusting screw ball head (12) of the valve adjusting screw (11) are connected by a shrinkage joint riveting. After riveting, the bowl mouth (15) of the elephant foot (13) and the screw neck (16) are connected by a hinged rivet lock. The valve adjusting screw (11) has an annular oil groove (17) in the middle. The annular oil groove (17) is connected to the transverse oil passage (18) and the straight oil passage (19) in the valve adjusting screw (11). The annular oil groove (17) is also connected to the rocker arm body oil passage (21). The nut (20) is installed on the valve adjusting screw (11).

Images