Valve rocker arm

Abstract

The application provides a valve rocker arm for acting on a cam of a camshaft of a valve system to provide different valve lifts, the valve rocker arm comprising an inner support (11) and an outer support (21), the outer support (21) being sleeved on the outer periphery of the inner support (11), two outer rollers (22) being arranged on the outer support (21), the outer rollers (22) being rotatable relative to the outer support (21), the outer rollers (22) being located between the outer support (21) and the inner support (11), and the outer rollers (22) being capable of contacting the cam when the valve rocker arm acts on the cam. The valve rocker arm according to the application has small friction with the cam and is not prone to wear.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engines for vehicles, and more specifically to a valve rocker arm for a valve system of an internal combustion engine. Background Technology

[0002] To improve the emission performance of vehicle internal combustion engines, these engines typically incorporate a valve system. Within this system, to achieve at least two different valve lifts, a switchable roller finger follower (SRFF), sometimes simply referred to as a valve rocker or rocker arm, can be used. The SRFF contacts a cam on the camshaft and transmits camshaft rotation to the valve pushrod, allowing the valve lift to switch between, for example, a "normal valve lift" and an "early valve closing lift." Such valve rockers are illustrated in, for example, Chinese patent publications CN110273725A and CN109944654A.

[0003] The valve rocker arm described in Chinese Patent Publication CN110273725A includes two rocker arms. The first rocker arm (i.e., the outer rocker arm) is rotatably connected to the second rocker arm (i.e., the inner rocker arm) via a pivot shaft. The two can rotate relative to each other or be locked. By changing the rotation angle of the inner rocker arm relative to the outer rocker arm, different motion guidance can be provided for the valve push rod connected to the inner rocker arm.

[0004] The outer rocker arm has two side plates with sliding pads on them. The contact point between the outer rocker arm and the cam is located at the sliding pad. The friction between the sliding pad and the cam during relative movement is sliding friction, which makes the sliding pad prone to wear, thus affecting the performance of the entire valve system. Summary of the Invention

[0005] The purpose of this invention is to overcome or at least mitigate the shortcomings of the prior art and to provide a valve rocker arm.

[0006] This invention provides a valve rocker arm that acts on a cam of a camshaft in a valve system to provide different valve lifts. The valve rocker arm includes an inner support and an outer support, the outer support being sleeved on the outer periphery of the inner support.

[0007] The outer support is provided with two outer rollers, which can rotate relative to the outer support. The outer rollers are located between the outer support and the inner support.

[0008] When the valve rocker arm acts on the cam, the outer roller can contact the cam.

[0009] In at least one embodiment, the outer support includes two sidewalls located on both sides of the inner support, the sidewalls protruding toward the inner support to form cylindrical bosses, and the outer rollers being rotatably connected to the bosses.

[0010] In at least one embodiment, a retaining ring is provided between the outer roller and the boss, the retaining ring restricting the outer roller to a defined position in the axial direction of the boss.

[0011] In at least one embodiment, the retaining ring has an opening and is C-shaped, and the retaining ring is elastic and can be compressed radially and return to its original shape.

[0012] In at least one embodiment, an annular retaining ring groove is formed at the axial midpoint of the boss and the outer roller, and the retaining ring is accommodated within the retaining ring groove.

[0013] The retaining ring groove includes an inner groove located on the inner periphery and an outer groove located on the outer periphery.

[0014] The inner groove is formed by the radial inward recess of the peripheral wall of the boss, and the outer groove is formed by the radial outward recess of the inner peripheral wall of the outer roller.

[0015] In at least one embodiment, the minimum outer diameter of the boss is d1, the minimum inner diameter of the outer roller is d4, the inner diameter of the retaining ring when it is in its original shape is D1, and the outer diameter of the retaining ring when it is in its original shape is D2, satisfying: (d1+(D2-D1))≤d4.

[0016] In at least one embodiment, the retaining ring contacts the outer peripheral wall of the boss, and the retaining ring extends partially into the outer groove.

[0017] In at least one embodiment, the retaining ring contacts the inner peripheral wall of the outer roller, and the retaining ring extends partially into the inner groove.

[0018] In at least one embodiment, the axial section of the outer roller is arc-shaped at the edge of the outer groove, and the axial section of the boss is arc-shaped at the edge of the inner groove.

[0019] In at least one embodiment, the cross-section of the retaining ring along the axial direction of the outer roller is circular.

[0020] According to the present invention, the friction between the valve rocker arm and the cam is small, and the valve rocker arm is not easily worn. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a valve rocker arm according to an embodiment of the present invention.

[0022] Figure 2yes Figure 1 A schematic diagram of a valve rocker arm cut along the axial direction of the inner roller.

[0023] Figure 3 This is a cross-sectional view of the outer roller in its installed state.

[0024] Figure 4 This is a schematic diagram of the retaining ring in its natural state and under pressure.

[0025] Figure 5 This is a schematic diagram showing the partial dimensions of the outer roller, retaining ring, and boss.

[0026] Figures 6 to 8 This is a schematic diagram showing the installation status of retaining rings of different sizes.

[0027] Figure 9 This is a schematic diagram of the process of installing the outer roller onto the boss.

[0028] Explanation of reference numerals in the attached figures:

[0029] 10. Inner rocker arm; 11. Inner bracket; 12. Inner roller;

[0030] 20 Outer rocker arm; 21 Outer bracket; 211 Side wall; 212 Boss; 22 Outer roller;

[0031] 30mm swivel; 40mm retaining ring; 40mm retaining ring opening;

[0032] G circlip groove; G1 inner groove; G2 outer groove;

[0033] d1 Minimum outer diameter of the boss; d2 Maximum inner diameter of the outer roller; d3 Maximum outer diameter of the boss; d4 Minimum inner diameter of the outer roller; D1 Original inner diameter of the retaining ring; D2 Original outer diameter of the retaining ring; W Radial width of the retaining ring. Detailed Implementation

[0034] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement the present invention, and are not intended to exhaustively describe all possible ways of the invention, nor to limit the scope of the invention.

[0035] Reference Figures 1 to 9 The valve rocker arm according to the present invention is described.

[0036] First refer to Figure 1 The valve rocker arm according to the present invention includes an inner rocker arm 10 and an outer rocker arm 20.

[0037] The inner rocker arm 10 includes an inner support 11 and an inner roller 12, with the inner roller 12 rotatably connected to the inner support 11.

[0038] The outer rocker arm 20 includes an outer support 21 and two outer rollers 22. The outer support 21 is frame-shaped and sleeved on the outer periphery of the inner support 11. The outer support 21 and the inner support 11 are rotatably connected by a pivot 30, allowing them to rotate relative to each other or be locked. The outer rollers 22 are located inside the outer support 21 and between the outer support 21 and the inner support 11, such that the two outer rollers 22 are located on opposite sides of the inner support 11. The rotation axes of the outer rollers 22 and the inner rollers 22 are parallel.

[0039] Simultaneously refer to Figure 2 The two side walls 211 of the outer bracket 21 that are perpendicular to the rotation axis of the outer roller 22 both protrude into the inner bracket 11 to form a boss 212. The boss 212 is cylindrical, so that the boss 212 can serve as the central axis to install the outer roller 22.

[0040] Each boss 212 is fitted with an outer roller 22. From Figure 2 As can be clearly seen, the outer roller 22 is clamped between the side wall 211 and the side wall of the inner support 11 in its axial direction. The outer roller 22 can rotate relative to the boss 212, so when the outer roller 22 contacts the cam, the outer roller 22 can form rolling friction with the cam, making the outer roller 22 less prone to wear.

[0041] Preferably, a retaining ring 40 is provided between the outer roller 22 and the boss 212, and the retaining ring 40 can play the role of axially limiting the outer roller 40.

[0042] Figure 3 It is a schematic diagram of the axial cross-section of the outer roller 22, the retaining ring 40 and the boss 212.

[0043] An annular retaining ring groove G is formed at the midpoint of the axial direction of the boss 212 and the outer roller 22, and the retaining ring 40 is accommodated in the retaining ring groove G. The retaining ring groove G includes an inner groove G1 located on the inner periphery and an outer groove G2 located on the outer periphery. Specifically, the peripheral wall of the boss 212 is concave radially inward to form the annular inner groove G1, and the inner peripheral wall of the outer roller 22 is concave radially outward to form the annular outer groove G2.

[0044] Figure 4 This is a schematic diagram of the retaining ring 40 viewed along the axial direction of the outer roller 22. The solid line represents the shape of the retaining ring 40 in its natural state (also referred to as the original shape of the retaining ring 40), and the dashed line represents the shape of the retaining ring 40 after being deformed under pressure.

[0045] The retaining ring 40 is C-shaped.

[0046] The snap ring 40 is radially elastic. In particular, when an external force directed radially inward acts on the outer periphery of the snap ring 40, the snap ring 40 is compressed and deformed, causing the opening 40m to become smaller. At this time, the snap ring 40 has a tendency to return to its original shape. When the external force decreases or is removed, the snap ring 40 can partially or completely return to its original shape. The material for making the snap ring 40 is, for example, steel.

[0047] Next, in combination with Figures 5 to 9 the limiting effect of the snap ring 40 on the outer roller 22 will be introduced.

[0048] Figure 5 Several parameters affecting the positioning effect of the snap ring 40 are shown. They are: the minimum outer diameter d1 of the boss, the maximum inner diameter d2 of the outer roller, the maximum outer diameter d3 of the boss, the minimum inner diameter d4 of the outer roller, the original inner diameter D1 of the snap ring (the inner diameter when the snap ring 40 is in its original shape), the original outer diameter D2 of the snap ring (the outer diameter when the snap ring 40 is in its original shape), and the radial width W of the snap ring, where W = (D2 - D1) / 2.

[0049] To enable the snap ring 40 to have a limiting effect, after the outer roller 22 is installed, the snap ring 40 may be in two states: (i) the snap ring 40 returns to its original shape, (ii) the snap ring 40 remains in a compressed state.

[0050] In the first state (i), the snap ring 40 may contact the outer peripheral wall of the boss 212 (as Figure 6 shown), or may contact the inner peripheral wall of the outer roller 22 (as Figure 7 shown). In the second state (ii), the snap ring 40 contacts the inner peripheral wall of the outer roller 22 (as Figure 8 shown).

[0051] To ensure the effective limiting of the outer roller 22 by the snap ring 40, it is necessary to satisfy that in all the above cases, part of the snap ring 40 is located in the inner groove G1 and part is located in the outer groove G2.

[0052] Specifically, when the snap ring 40 contacts the outer peripheral wall of the boss 212, it is necessary to satisfy: D2 ≤ d2 (the snap ring 40 is not in a compressed state), D1 > d1 (the snap ring 40 is not in a state of being expanded at this time), and D2 > d4 (the snap ring 40 partially extends into the outer groove G2).

[0053] When the snap ring 40 contacts the inner peripheral wall of the outer roller 22, it is necessary to satisfy: D2 ≥ d2 (the snap ring 40 contacts the inner peripheral wall of the outer roller 22), and (d2 - 2×W) < d3 (the snap ring 40 partially extends into the inner groove G1).

[0054] Figure 9 A schematic diagram of an intermediate state in the process of installing the outer roller 22 onto the boss 212 is shown, and the snap ring 40 in the figure is in a compressed state.

[0055] In order for the retaining ring 40 to be installed between the outer roller 22 and the boss 212, it is necessary to satisfy that when the retaining ring 40 is placed in the inner groove G1, the smallest inner diameter of the outer roller 22 can allow the retaining ring 40 to pass through, that is, (d1+2×W)≤d4, or (d1+(D2-D1))≤d4.

[0056] It should be understood that Figures 2 to 9 The spacing between the outer roller 22, boss 212 and retaining ring 40 shown is only schematic and is not intended to represent the actual spacing or proportion between the components.

[0057] Preferably, the cross-section of the retaining ring 40 along the axial direction of the outer roller 22 is circular, the edge of the cross-section of the outer roller 22 along the axial direction at the outer groove G2 is arc-shaped, and the edge of the cross-section of the boss 212 along the axial direction at the inner groove G1 is arc-shaped. These features facilitate the installation of the outer roller 22, the boss 212, and the retaining ring 40, and reduce the friction between the retaining ring 40 and the outer roller 22 or the boss 212 during the rotation of the outer roller 22 relative to the boss 212.

[0058] This invention has at least one of the following advantages:

[0059] (i) According to the present invention, the friction between the valve rocker arm and the cam of the camshaft is small, and the valve rocker arm is not easily worn, thereby improving the reliability of the entire valve system.

[0060] (ii) The limiting structure of the outer roller 22 of the valve rocker arm is simple and the outer roller 22 is easy to install.

[0061] Of course, the present invention is not limited to the above embodiments. Those skilled in the art can make various modifications to the above embodiments of the present invention under the guidance of the present invention, without departing from the scope of the present invention.

Claims

1. A valve rocker arm for acting on a cam of a camshaft of a valve system to provide different valve lifts, said valve rocker arm comprising an inner support (11) and an outer support (21), said outer support (21) being sleeved on the outer periphery of said inner support (11), wherein, The outer support (21) is provided with two outer rollers (22), which are rotatable relative to the outer support (21). The outer rollers (22) are located between the outer support (21) and the inner support (11). When the valve rocker arm acts on the cam, the outer roller (22) can contact the cam. The outer support (21) includes two sidewalls (211) located on both sides of the inner support (11). The sidewalls (211) protrude towards the inner support (11) to form a cylindrical boss (212). The outer roller (22) is rotatably connected to the boss (212). A retaining ring (40) is provided between the outer roller (22) and the boss (212). The retaining ring (40) restricts the outer roller (22) to a certain position in the axial direction of the boss (212).

2. The valve rocker arm according to claim 1, characterized in that, The retaining ring (40) has an opening (40m) and is C-shaped. The retaining ring (40) is elastic and can be compressed radially and return to its original shape.

3. The valve rocker arm according to claim 1, characterized in that, The boss (212) and the outer roller (22) have an annular retaining ring groove (G) formed at their axial center, and the retaining ring (40) is accommodated in the retaining ring groove (G). The retaining ring groove (G) includes an inner groove (G1) located on the inner periphery and an outer groove (G2) located on the outer periphery. The inner groove (G1) is formed by the radial inward recess of the peripheral wall of the boss (212), and the outer groove (G2) is formed by the radial outward recess of the inner peripheral wall of the outer roller (22).

4. The valve rocker arm according to claim 3, characterized in that, The minimum outer diameter of the boss (212) is d1, the minimum inner diameter of the outer roller (22) is d4, the inner diameter of the retaining ring (40) when it is in its original shape is D1, and the outer diameter of the retaining ring (40) when it is in its original shape is D2, satisfying: (d1+(D2-D1))≤d4.

5. The valve rocker arm according to claim 3, characterized in that, The retaining ring (40) contacts the outer peripheral wall of the boss (212), and the retaining ring (40) extends partially into the outer groove (G2).

6. The valve rocker arm according to claim 3, characterized in that, The retaining ring (40) contacts the inner peripheral wall of the outer roller (22), and the retaining ring (40) extends partially into the inner groove (G1).

7. The valve rocker arm according to any one of claims 3 to 6, characterized in that, The axial section of the outer roller (22) is arc-shaped at the edge of the outer groove (G2), and the axial section of the boss (212) is arc-shaped at the edge of the inner groove (G1).

8. The valve rocker arm according to any one of claims 1 to 6, characterized in that, The cross section of the retaining ring (40) along the axial direction of the outer roller (22) is circular.

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