US20140283774A1

US20140283774A1 - Rocker arm assembly and method of lubricating a valve train

Info

Publication number: US20140283774A1
Application number: US13/848,844
Authority: US
Inventors: Edwin H. Langewisch
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2013-03-22
Filing date: 2013-03-22
Publication date: 2014-09-25
Also published as: CN105189944A; WO2014153401A1

Abstract

A method of lubricating one or more valve train (100) components includes delivering a lubricating fluid to the inner cavity (156) of a fluid collecting member (152) through a radially extending discharge portion (182) of a fluid passage (176) in a rocker arm insert. The insert fluid passage (176) is in fluid communication with a lubricating fluid source to dispense a controlled amount of lubricating fluid to one or more valve train components during operation of an engine. The radially extending discharge portion of the fluid passage in the insert may be positioned adjacent to a spherical end cap that is received in the inner cavity of the fluid collecting member.

Description

TECHNICAL FIELD

The present disclosure relates generally to a method of lubricating a valve train and, more particularly, to a method of lubricating one or more valve train components including dispensing a lubricating fluid through a hole extending radially through a rocker arm insert.

BACKGROUND

Internal combustion engines, including diesel engines, gasoline engines, gaseous fuel-powered engines, and other engines known in the art, typically include a valve train. The valve train includes intake and exhaust valves in a combustion chamber and a mechanism to cause the valves to open and close. The valve train may include a rocker arm that is pivoted through engagement with a cam positioned on a rotating camshaft to generate the required opening and closing of the intake and exhaust valves. In some instances the valve train may include a hydraulic lash adjuster (HLA) to maintain the desired valve lift and eliminate the need for periodic adjustment of the valves. A lubricating mechanism may also be provided in the valve train to lubricate valve train components during operation.
U.S. Patent Application Publication No. 2003/0037744 to Yates (the '744 publication) discloses a method of retaining a rocker lever ball socket on a rocker lever ball of a rocker lever. The rocker lever ball includes a first fluid channel in fluid communication with an engine and the rocker lever ball socket includes a second fluid channel. The first and second fluid channels align at a predetermined rotation of a rocker lever shaft to complete a fluid path to the exterior of the rocker lever ball socket. However, the lubrication method contemplated by the '744 publication is not ideal in all valve trains and can result in insufficient or excessive lubrication under certain conditions.
The method and apparatus of the present disclosure alleviates one or more deficiencies of the prior art.

SUMMARY OF THE INVENTION

Another aspect of the present disclosure relates to a rocker arm insert assembly comprising: a rocker arm including a first fluid passage therein; and an insert including a first end carried by the rocker arm, a second end opposite the first end, and a second fluid passage, wherein the second fluid passage in the insert is in fluid communication with the first fluid passage in the rocker arm and the second fluid passage includes a discharge portion extending radially to an outer surface of the insert.
One aspect of the present disclosure relates to a method of lubricating one or more valve train components comprising the steps of supplying a lubricating fluid to a fluid passage in an insert in a rocker arm, the insert having a first end carried by the rocker arm and a second end movably secured to a fluid collecting member; and dispensing the lubricating fluid onto the fluid connecting member through a radially extending discharge portion of the fluid passage in the insert.
One aspect of the present disclosure relates to a rocker arm assembly comprising a rocker arm including a first fluid passage therein; and an insert having a first end carried by the rocker arm, a second end opposite the first end and adapted to be movably connected to a fluid collecting member, and a second fluid passage in the insert, wherein the second fluid passage in the insert is in fluid communication with the first fluid passage in the rocker arm and the second fluid passage includes an axial portion extending longitudinally along the insert and a discharge portion extending radially to an outer surface of the insert, the discharge portion being positioned to deliver lubricating fluid to the fluid collecting member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagrammatic view of part of a valve train including a rocker arm assembly according to the concepts of the present disclosure;

FIG. 2 is a section diagrammatic view of the rocker arm assembly as indicated in FIG. 1;

FIG. 3 is a section view of a rocker arm including a rocker arm insert according to the concepts of the present disclosure, as indicated in FIG. 1; and

FIG. 4 is a section view of a rocker arm insert and fluid collecting member according to the concepts of the present disclosure;

DETAILED DESCRIPTION

Referring now to FIG. 1, a portion of a valve train is depicted and is indicated generally by the numeral 100. Valve train 100 is a sub-assembly of an internal combustion engine and generates the necessary opening and closing of the intake and exhaust valves in the combustions chambers.
Valve train 100 includes one or more rocker arms 102 mounted on and capable of pivoting about a rocker arm shaft 104 (FIG. 2). Although not shown in FIG. 1, each rocker arm shaft 104 extends along at least a portion of the length of an engine adjacent to the intake and exhaust valves 106 and 108. The rocker arm shaft 104 may include a passage 107 configured to convey lubricating fluid from a lubricating fluid reservoir such as an engine, for example, through the rocker arm shaft 104 to one or more valve train components. As best shown in FIG. 1, the rocker arms 102 are axially spaced so that they each align with intake or exhaust valves, 106 and 108 respectively. A camshaft 111 includes a plurality of axially spaced cams 110 to provide the desired timing to the valve train. A connecting rod 112 extends between each of the cams 110 on the camshaft 111 and a hydraulic lash adjuster (HLA) 113 that is positioned at one end of and engaged with the rocker arm 102. Each connecting rod 112 may include a roller assembly 109 that engages the cam 110 on the camshaft 111.
Referring to FIG. 2, the HLA 113 may include a body 114 and a plunger 116, each having an internal oil cavity. The oil may flow into a low pressure chamber 118 in the plunger 116 and then may pass through a one-way valve 120 into a high pressure chamber 122 within the body 114. The plunger 116 may slide within the body 114 to increase the effective length of the HLA 113, thereby taking up any clearance within the valve train. The one-way valve 120 may prevent the plunger 116 from retracting into the body and thereby decreasing the effective length of the HLA 113.
In operation of the engine the roller assembly 109 rides on the outer surface of the cam 110 to generate a reciprocating motion of the connecting rod 112, causing pivoting of the rocker arms 102 about the rocker arm shaft 104. The number and spacing of the rocker arms 102 and cams 110, and the related components, may vary depending upon the particular size and design of the engine, and in particular depending upon the number of intake and exhaust valves 106 and 108.
Referring now to FIGS. 2 and 3, rocker arm 102 will be described in greater detail. Each rocker arm 102 includes a body 124 having a hole 126 adapted to receive a rocker arm bearing 128. Rocker arm bearing 128 may be positioned within the hole 126 to rotatably support the rocker arm shaft 104 (FIG. 2) to reduce friction forces and facilitate pivoting of the rocker arm about the shaft, as is customary. The rocker arm bearing 128 may include one or more openings or channels 130 (FIG. 3) to allow for fluid transfer from the rocker arm shaft 104. The hole 126 through body 124 may be generally cylindrical in shape, and the bearing 128 may be generally annular in shape with an outer diameter generally corresponding to the inner diameter of the 126.
As best seen in FIG. 3, the body 124 of the rocker arm 102 includes a first arm 132 extending in a first radial direction away from the hole 126 and a second arm 134 extending in a second radial direction away from the hole 126. One or both of the first and second arms 132, 134 may have a reduced cross sectional area as it extends away from the hole 126 in the body 124. The first arm 132 may include a first enlarged end portion 133 at an end opposite the hole 126, the first enlarged end portion 133 adapted to receive an insert therein. Similarly, the second arm 134 may include a second enlarged end portion 135 at an end opposite the hole 126, the second enlarged end portion 135 adapted to receive an insert therein. One or both of the first and second enlarged end portions 133, 135 may have a generally cylindrical outer surface, the cylindrical outer surface defining a center axis that is oriented generally perpendicular to the axis of rotation of the rocker arm shaft 104.
A first bore 136 may be provided in the first enlarged end portion 133 of the first arm 132. The first bore 136 may be generally cylindrical in shape and may be positioned substantially concentrically within the first enlarged end portion 133. Thus, the first bore 136 may have a center axis that is oriented generally perpendicular to the axis of rotation of the rocker arm shaft 104. In an exemplary embodiment, the first bore 136 may be a blind bore extending less than entirely through the first enlarged end portion 133 of first arm 132. However, it is also contemplated that a through bore may be provided that extends though the entirety of the first enlarged end portion 133.
Similarly, a second bore 138 may be provided in the second enlarged end portion 135 of the second arm 134. The second bore 138 may be generally cylindrical in shape and may be positioned substantially concentrically within the second enlarged end portion 135. Thus, the second bore 138 may have a center axis that is oriented generally perpendicular to the axis of rotation of the rocker arm shaft 104. In the embodiment depicted, the second bore 138 is a through bore that extends through the entirety of the second arm 134. However, similar to first bore 136, the second bore 138 may alternatively be provided as a blind bore.
A first rocker arm insert 140 may be carried by and extend from the first enlarged end portion 133. At least a portion of the first rocker arm insert 140 may be received in the first bore 136 and secured therein to resist removal. Similarly, a second rocker arm insert 142 may be carried by and extend from the second enlarged end portion 135. At least a portion of the second rocker arm insert 142 may be received in the second bore 138 and secured therein to resist removal. The first and second rocker arm inserts 140, 142 may be secured in the first and second bores 136, 138, respectively, by any method or mechanism known to those skilled in the art, including, but not limited to, a press fit, a threaded attachment, or other mechanical retention system.
The first rocker arm insert 140 may include body member 144 having a first end 146 and a second end 148 located on opposing longitudinal ends of the body member 144. The axial distance between the first end 146 and second end 148 defines a longitudinal length L of the first rocker arm insert 140. At least a portion of the body member 144 adjacent to the first end 146 may have a shape, as defined by an outer surface 150, that is adapted to be received in the first bore 136 in the first arm 132 of the rocker arm body 124.
The second end 148 of the first rocker arm insert 140 may be movably connected to a fluid collecting member 152 to allow the first rocker arm insert 140 to pivot relative to the fluid collecting member 152. In an exemplary embodiment, the second end 148 of the first rocker arm insert 140 may include a spherical cap 154, and the fluid collecting member 152 may include an inner cavity 156 having a generally spherical well portion 157. The spherical cap 154 may be formed by a generally spherical end portion having a shoulder 158 defined by an intersecting plane on an upper side of the spherical end portion. The spherical cap 154 and the generally spherical well portion 157 together form a ball-and-socket type joint that allows a degree of rotational movement between the fluid collecting member 152 and the first rocker arm insert 140. While a particular movable connection has been described herein and shown in the drawings, it is also contemplated that other known movable connecting mechanisms may be used to movably secure the first rocker arm insert 140 to the fluid collecting member 152.
The fluid collecting member 152 may further include an annular depression 160 at a top edge of the generally spherical well portion 157, the annular depression 160 having an increased diameter D₄as compared to the diameter D₃of the generally spherical well portion 157 and providing an increased volume of the inner cavity 156 formed within the fluid collecting member 152 (see FIG. 4). In exemplary embodiments, the annular depression 160 may have a diameter D₄of between approximately 8 and 24 mm. The inner cavity 156 in the fluid collecting member 152 may include an upper opening 162 having a diameter D₅approximately equal to the diameter D₃of the generally spherical well portion 157.
The spherical cap 154 of the insert may have a diameter D₁larger than the diameter D₂of the body member 144 and approximately equal to the diameter D₃of the generally spherical well portion 157 in the fluid collecting member 152. Thus, the dimensional relationship of the components may be described as follows:
D ₂<(D ₁ , D ₃ , D ₅)<D ₄
where D₁is the diameter of the spherical cap 154, D₂is the diameter of the body member 144, D₃is the diameter of the generally spherical well portion 157, D₄is the diameter of the annular depression 160 and D₅is the diameter of the upper opening 162.
The diameter D₁of the spherical cap 154, and therefore the approximate diameters D₃and D₅of the generally spherical well portion 157 and the upper opening 162 respectively, may be between approximately 7 and 22 mm, in other embodiments between approximately 10 and 20 mm, and in yet other embodiments between approximately 12 and 17. In an exemplary embodiment, the diameter D₂of the body member 144 may be between approximately 4 and 10 mm and the diameter D₅of the upper opening may be between 7 and 22 mm.
The inner cavity 156 of the fluid collecting member 152 may have a height H₁measured from the bottom of the spherical well portion 157 to a top surface 153 of the fluid collecting member 152 adjacent to the upper opening 162 that is between approximately 4 and 12 mm, and in an exemplary embodiment is approximately 10 mm.
In particular embodiments, the fluid collecting member 152 may be provided in the form of a rocker arm button positioned on a top surface of a bridge 163 (FIG. 2) that extends between two adjacent valve retainers projecting from the intake valves 106 or exhaust valves 108. The generally spherical cap 154 of the first rocker arm insert 140 and the generally spherical well portion 157 in the fluid collecting member 152 may allow for pivoting movement between the rocker arm 102 and the bridge 163.
Referring back to the first rocker arm insert 140, as best shown in FIG. 3, a rocker arm fluid passage 166 extends through the rocker arm body 124 from an opening 168 at the inner surface of the hole 126 and terminates at an opening 170 in the first bore 136. A substantially circumferential recess 164 may be provided in the outer surface 150 of the body member 144 adjacent to the first end 146. This circumferential recess 164 may create a generally circumferential fluid chamber between the first rocker arm insert 140 and the first bore 136. The opening 168 in the hole 126 may be aligned with the bearing channel 130 in the rocker arm bearing 128, and the opening 170 in the first bore 136 is in fluid communication with the circumferential recess 164. In a particular embodiment, the rocker arm fluid passage 166 may be formed as a through bore, thereby creating an access bore 172 extending from the first bore 136 to an end of the first arm 132 of the rocker arm body 124. This access bore 172 may be sealed by a plug or gasket 174, or other sealing mechanisms known to those skilled in the art.
An insert fluid passage 176 can extend through at least a portion of the first rocker arm insert 140 and may have an opening in the outer surface 177 of the spherical cap 154. The insert fluid passage 176 may include an axial portion 178 extending longitudinally along the first rocker arm insert 140 at least partially between the first end 146 and second end 148. In a particular embodiment the axial portion 178 of the insert fluid passage 176 may be a blind bore extending from the outer surface 177 of the spherical cap 154 to an end point 179 adjacent to the first end 146. A radial inlet passage 180 may extend through the first rocker arm insert 140 between the axial portion 178 of the insert fluid passage 176 and the circumferential recess 164 to facilitate fluid communication between the rocker arm fluid passage 166 and the insert fluid passage 176.
The insert fluid passage 176 may also include a discharge portion 182 extending radially from the axial portion 178 to the outer surface 150 of the first rocker arm insert 140. The discharge portion 182 may be located in the body member 144 of the first rocker arm insert 140 adjacent to the spherical cap 154. The discharge portion 182 may define an exit orifice 184 in the outer surface 150 of the body member 144. The exit orifice 184 may be positioned adjacent to the shoulder 158 of the spherical cap 154. In an exemplary embodiment the discharge portion 182 may extend at an approximate right angle relative to the axial portion 178 of the insert fluid passage. However, it is contemplated that the discharge portion 182 may be alternatively oriented relative to the axial portion 178 while extending radially toward the outer surface 150, such as, for example, by extending at an approximately 45 degree angle relative to the axial portion 178.
In certain embodiments, the discharge portion 182 of the first rocker arm insert 140 may have a diameter of less than approximately 1.75 mm (0.07 inch), in other embodiments a diameter of less than approximately 1.70 mm (0.07 inch), and in yet other embodiments a diameter of less than approximately 1.65. In the same or other embodiments, the discharge portion 182 of the first rocker arm insert 140 may have a diameter of between approximately 1.40 and 1.80 mm (0.06 and 0.07 inch), in other embodiments between 1.45 and 1.75 mm (0.06 and 0.07 inch), and in yet other embodiments between 1.50 and 1.70 mm (0.06 and 0.07 inch). In a particular embodiment, the discharge portion 182 may have a diameter of approximately 1.60 mm (0.06 inch). In an exemplary embodiment the axial portion 178 of the insert fluid passage 176 may have a diameter equal to the diameter of the discharge portion 182 to allow for manufacturing efficiency.
The exit orifice 184 of the discharge portion 182 may be longitudinally spaced from a distal end 185 of the spherical cap 154 by a distance H₂of between approximately 4 and 10 mm. The distance H₂that the exit orifice 184 is spaced from the distal end 185 may be less than the height H₁of the inner cavity 156 to ensure that the exit orifice 184 is positioned within the inner cavity 156 when the first rocker arm insert 140 is movably secured to the fluid collecting member 152.
The second rocker arm insert 142 may be similar in many respects to the first rocker arm insert 140, and in certain embodiments may be substantially identical absent the spherical cap 154 feature. However, it is also contemplated that the second rocker arm insert 142 may include distinctions from the first rocker arm insert 140. In an exemplary embodiment the second rocker arm insert 142 may be secured in the second bore 138 by a nut 186 threaded over a threaded top portion 188 of the second rocker arm insert 142.
The second rocker arm insert 142 may be operatively engaged with the connecting rod 112. In a particular embodiment, the bottom surface 190 of the second rocker arm insert 142 may engage the plunger 116 of the HLA 113 (FIG. 2), the HLA being operatively engaged with the connecting rod 112 extending toward the camshaft 111 (FIG. 1). The HLA 113 may be in fluid communication with the rocker arm shaft 104 through one or more fluid passages 192, 194 in the second arm 134 of the rocker arm body 124 and second rocker arm insert 142, respectively. Hydraulic fluid may be delivered through an opening 196 in the bottom surface 190, as defined by the fluid passage 194 in the second rocker arm insert 142, into the low pressure chamber 118 within the HLA 113.

INDUSTRIAL APPLICABILITY

The disclosed method of lubricating one or more valve train components, and the disclosed rocker arm assembly and rocker arm insert, may be useful in any internal combustion engine including diesel engines, gasoline engines, gaseous fuel-powered engines, and other engines known in the art. More particularly, the disclosed method and apparatus may be useful in an internal combustion engine that includes an HLA within the valve train. The HLA may render known valve train lubrication methods and mechanisms ineffective due, at least in part, to reduced clearances between components of the valve train.
The method of the present disclosure contemplates lubricating one or more components of the valve train by dispensing lubricating fluid from a radial discharge portion 182 of a fluid passage 176 in a rocker arm insert. The lubricating oil is provided to the rocker arm bearing 128 by a hole in the rocker arm shaft 104. The oil then travels through the rocker arm fluid passage 166 in the first arm 132 of the rocker arm body 124. The lubricating fluid then flows from the rocker arm fluid passage into the insert fluid passage 176 and exits from the insert through a radial discharge portion 182 and exit orifice 184. The lubricating fluid may then be captured by the inner cavity 156 in the fluid collecting member 152, thereby minimizing the amount of oil mist generated, which in turn may minimize the oil load on a crankcase ventilator mounted adjacent to the rocker arm assembly.
It will be apparent to those skilled in the art that various modifications and variations can be made to the method of lubricating a valve train and rocker arm insert of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the method and device disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalent.

Claims

What is claimed is:

1. A rocker arm assembly comprising:

a rocker arm including a first fluid passage therein; and

an insert including a first end carried by the rocker arm, a second end opposite the first end, and a second fluid passage,

wherein the second fluid passage in the insert is in fluid communication with the first fluid passage in the rocker arm and the second fluid passage includes a discharge portion extending radially to an outer surface of the insert.

2. The rocker arm assembly of claim 1, the second fluid passage in the insert including an axial portion extending between the first end and the discharge portion.

3. The rocker arm assembly of claim 1, further comprising a radially extending inlet passage extending from the outer surface of the insert to the second passage adjacent to the first end of the insert.

4. The rocker arm assembly of claim 3, further comprising a recess in the outer surface in axial alignment with the radially extending inlet passage.

5. The rocker arm assembly of claim 1, wherein said second fluid passage, including the discharge portion, has a diameter of between approximately 1.4 and 1.8 mm.

6. A method of lubricating one or more valve train components comprising the steps of:

(a) supplying a lubricating fluid to a fluid passage in an insert in a rocker arm, the insert having a first end carried by the rocker arm and a second end movably secured to a fluid collecting member; and

(b) dispensing the lubricating fluid onto the fluid connecting member through a radially extending discharge portion of the fluid passage in the insert.

7. The method of claim 6, wherein the step of supplying a lubricating fluid includes delivering the lubricating fluid to the rocker arm through a rocker arm shaft.

8. The method of claim 7, wherein the step of supplying a lubricating fluid further includes conveying the lubricating fluid from the rocker arm shaft through a fluid passage in the rocker arm to the rocker arm insert.

9. The method of claim 6, further comprising the step of conveying the lubricating fluid through an axial portion of the passage in the rocker arm insert and then into the radially extending discharge portion of the fluid passage in the insert.

10. The method of claim 6, wherein the fluid collecting member is a rocker arm button having a recess that receives the second end of the insert, and wherein the lubricating fluid is dispensed into the recess in the rocker arm button.

11. A rocker arm assembly comprising:

a rocker arm including a first fluid passage therein;

a fluid collecting member including an inner cavity; and

an insert having a first end carried by the rocker arm, a second end received in the inner cavity of the fluid collecting member and movable relative to the fluid collecting member, and a second fluid passage,

wherein the second fluid passage in the insert is in fluid communication with the first fluid passage in the rocker arm and the second fluid passage includes an axial portion extending longitudinally along the insert and a discharge portion extending radially to an outer surface of the insert and terminating in an exit orifice, the discharge portion positioned to deliver lubricating fluid to the inner cavity of the fluid collecting member.

12. The rocker arm assembly of claim 11, further comprising a radially extending inlet passage extending from the outer surface of the insert to the axial portion of the second passage adjacent to the first end of the insert.

13. The rocker arm assembly of claim 12, further comprising a recess in the outer surface in axial alignment with the radially extending inlet passage.

14. The rocker arm insert assembly of claim 11, wherein the inner cavity has a height H₁and the exit orifice is spaced from the second end of the insert by a distance H₂, the distance H₂being less than the height of the inner cavity H₁.

15. The rocker arm assembly of claim 11, wherein the insert is generally cylindrical in shape and the axial portion of the second fluid passage is positioned substantially concentrically within the insert.