US20160222834A1

US20160222834A1 - Valve lifter assembly of engine

Info

Publication number: US20160222834A1
Application number: US15/095,093
Authority: US
Inventors: Jakub M. Walczak; Kevin Yoder; Sahul Hameed Peer Mohamed
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2016-04-10
Filing date: 2016-04-10
Publication date: 2016-08-04
Also published as: CN206636610U

Abstract

A valve lifter assembly for an engine is provided. The valve lifter assembly includes a first valve lifter and a second valve lifter received through a first bore and a second bore, respectively, of a cylinder head. The valve lifter assembly includes a spacer disposed between the first valve lifter and the second valve lifter. The spacer constrains rotation of the first and second valve lifters within a predefined angle range. A pair of first bevel surfaces is adapted to provide a surface contact with a first inner face of the first valve lifter. A pair of second bevel surfaces is adapted to provide a surface contact with a second inner face of the second valve lifter. A second recessed surface is defined between each of the pair of second bevel surfaces.

Description

TECHNICAL FIELD

The present disclosure relates to a valve lifter assembly of an engine.

BACKGROUND

Generally, an engine includes a camshaft and valve lifters to operate intake valves and exhaust valves of the engine. Each of the valve lifters is inserted through a bore formed in a cylinder head of the engine. The valve lifters include rollers that engage with a lobe of the camshaft such that a rotational movement of the camshaft is converted to reciprocating movement of the valve lifters within the bores of the cylinder head. In turn, the reciprocating movement of the valve lifter operates the exhaust and intake valves. During operation of the engine, each of the valve lifters may rotate within the cylinder bore about a longitudinal axis thereof Such rotational movement of the valve lifters may cause premature failure of the valve lifters due to wear thereof, which in turn may require frequent maintenance and servicing of the engine. Such rotational movement of the valve lifters may also cause degradation in performance of the engine and may lead to catastrophic engine failure,
U.S. Pat. No. 7,409,940 (the '940 patent) discloses an apparatus and a method for maintaining controlled orientation of a roller lifter follower used in conjunction with a variable phased lifter. In a variable phased valve lifter of an internal combustion engine, two or more roller lifters are allowed to move along constraining faces of a constraining mechanism in a first direction. The constraining mechanism is allowed to move freely in a second direction. As the roller lifters move through their parallel acute paths, one or more engaging surfaces of the roller lifters engage with one or more constraining faces of the constraining mechanism. Further, each roller lifter prevents the other roller lifter from rotating about its longitudinal axis. The roller lifter is thus prevented from rotating about its longitudinal axis as it moves in arcuate fashion in cooperation with the constraining mechanism. However, the constraining mechanism, as disclosed in the '940 patent, may not prevent rotation of both roller lifters about their respective longitudinal axes, independently.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a valve lifter assembly coupled to a cylinder head of an engine is provided. The valve lifter assembly includes a first valve lifter received through a first bore of the cylinder head. The first valve lifter has a first axis. The first valve lifter includes a first roller receiving portion having a first inner face. The valve lifter assembly also includes a second valve lifter received through a second bore of the cylinder head. The second valve lifter has a second axis. The second valve lifter includes a second roller receiving portion having a second inner face. The valve lifter assembly further includes a spacer coupled to an underside of the cylinder head and disposed between the first valve lifter and the second valve lifter. The spacer is adapted to constrain rotation of the first valve lifter about the first axis and the second valve lifter about the second axis, within a predefined angle range. The spacer includes a first surface. The spacer also includes a second surface distal to the first surface. The second surface is adapted to abut the underside of the cylinder head. The spacer further includes a plurality of side surfaces extending between the first surface and the second surface. The side surfaces include a pair of first bevel surfaces adapted to provide a surface contact with the first inner face of the first roller receiving portion. The side surfaces also include a first recessed surface defined between each of the pair of first bevel surfaces. The pair of first bevel surfaces and the first recessed surface are adapted to define a first clearance with the first inner face of the first roller receiving portion to receive a lubricating oil therein. The plurality of side surfaces also includes a pair of second bevel surfaces adapted to provide a surface contact with the second inner face of the second roller receiving portion. The plurality of side surfaces further includes a second recessed surface defined between each of the pair of second bevel surfaces. The pair of second bevel surfaces and the second recessed surface are adapted to define a second clearance with the second inner face of the second roller receiving portion to receive the lubrication oil therein. Further, the spacer includes at least one hole extending between the first surface and the second surface. At least one hole is adapted to receive a fastening member therethrough to couple the spacer with the cylinder head. During operation of the engine, the first clearance defined between the first inner face of the first roller receiving portion and the spacer, the second clearance defined between the second inner face of the second roller receiving portion, and the spacer constrain rotation of the first valve lifter and the second valve lifter, respectively, within the pre-defined angle range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side view of an engine having a valve lifter assembly, according to one embodiment of the present disclosure;

FIG. 2 is a bottom perspective view of a cylinder head of the engine;

FIG. 3 is a bottom perspective view of the valve lifter assembly of the engine;

FIG. 4 is an exploded view of the valve lifter assembly of FIG. 3;

FIG. 5 is a perspective view of a spacer of the valve lifter assembly of FIG. 3; and

FIG. 6 is a bottom perspective view of the valve lifter assembly of FIG. 3.

DETAILED DESCRIPTION

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. FIG. 1 is a diagrammatic view of a portion of an engine 10. The engine 10 is any internal combustion engine which runs on fuels, such as diesel, gasoline, gaseous fuels, or a combination thereof The engine 10 can be used to power various types of machines associated with an industry including, but not limited to, transportation, construction, mining, agriculture, forestry, waste management and material handling.
The engine 10 can be of a single-cylinder type (as shown), or a multi cylinder engine. The engine is an inline-type single-cylinder engine 10, however, it will be appreciated that the embodiments described herein may be used in any suitable configuration of the engine 10, including, but not limited to, V-type, radial, rotary or the like. Further, the engine 10 may be of any type, such as diesel or gasoline compression ignition engine, spark ignition engine, direct or port injection engine, and the like.
The engine 10 includes a cylinder block 12. The cylinder block 12 defines a cylinder 11 that receives a piston 13 adapted to reciprocate between a top-dead-center position and a bottom-dead-center position therein. A connecting rod 19 connects the piston 13 to a crankshaft 21 of the engine 10 such that reciprocating motion of the piston 13 between the top-dead-center position and the bottom-dead-center position results in a rotational motion of the crankshaft 21.
The engine 10 also includes a cylinder head 14 mounted on the cylinder block 12, The cylinder head 14 defines two intake ports 15 and two exhaust ports 20 (shown in FIG. 2) therein. The intake ports 15 and the exhaust ports 20 allow intake of gases into the cylinder II and exhaust of gases out of the cylinder 11, respectively. The cylinder head 14 also defines a first bore 16 (shown in FIG. 4) and a second bore 18 (shown in FIG. 4).
The engine 10 includes an inlet valve assembly 17. The inlet valve assembly 17 is actuated to control a flow of gases into the cylinder 11 through a corresponding intake port 15. In an example, the inlet valve assembly 17 includes two inlet valves 17A received within the intake ports 15, a first rocker arm 17B connected to the inlet valves 17A and a first push rod 17C connected to the first rocker arm 173. The engine 10 also includes an exhaust valve assembly (not shown) similar to the inlet valve assembly 17. The exhaust valve assembly is actuated to control a flow of exhaust gases from the cylinder 11 through the corresponding exhaust ports 20. In an example, the exhaust valve assembly also includes two exhaust valves 22 (shown in FIG, 2) received within the exhaust ports 20, a second rocker arm (not shown) connected to the exhaust valves 22 and a second push rod (not shown) connected to the second rocker arm.
The engine 10 further includes a camshaft 23 disposed within the cylinder block 12. The camshaft 23 operatively engages with the crankshaft 21 such that a rotational movement of the crankshaft 21 causes a corresponding rotational movement of the camshaft 23. In turn, rotational movement of the camshaft 23 actuates the inlet valves 17A and the exhaust valves 22, respectively, to selectively open and close the intake ports 15 and exhaust ports 20. The camshaft 23 includes multiple cam lobes 25 spaced apart from each other along a length thereof.
FIG. 2 is a bottom perspective view of the cylinder head 14 of the engine 10. The engine 10 also includes a valve lifter assembly 26 attached to the underside 64 of the cylinder head 14. Referring to FIGS. 1 and 2, the valve lifter assembly 26 is associated with the inlet valve assembly 17 and the exhaust valve assembly. Further, the valve lifter assembly 26 engages with the camshaft 23 such that rotational motion of the camshaft 23 causes actuation of the inlet valves 17A and the exhaust valves 22.
FIG. 3 is a bottom perspective view of the valve lifter assembly 26. The valve lifter assembly 26 is provided to operate the inlet valves 17A and the exhaust valves 22 of the engine 10. Alternatively, the valve lifter assembly 26 may be provided to operate one of a pair of the inlet valves 17A and one of a pair of the exhaust valves 22 of the engine 10. The valve lifter assembly 26 includes a first valve lifter 32 adapted to operate the inlet valves 17A, and a second valve lifter 34 adapted to operate the exhaust valves 22. The first valve lifter 32 and the second valve lifter 34 have a first axis A-A′ and a second axis B-B′, respectively.
The first valve lifter 32 includes a first roller receiving portion 36 and a first roller 38 rotatably mounted on the first roller receiving portion 36. The first roller receiving portion 36 is an elongated member extending along the first axis A-A′. The first roller receiving portion 36 defines a first cavity 40 at a first end 42. The first cavity 40 of the first roller receiving portion 36 receives the first roller 38. In particular, the first roller 38 is connected to the first roller receiving portion 36 via a bearing member (not shown) at the first end 42, such that the first roller 38 is rotatable about a first transverse axis C-C′ perpendicular to the first axis A-A′. The first roller 38 engages with a corresponding cam lobe 25 for actuating the inlet valves 17A such that the rotational motion of the camshaft 23 causes reciprocating motion of the first valve lifter 32. Further, a second end 43 (see FIG. 1) of the first valve lifter 32 engages with the first push rod 17C for transferring the reciprocating motion of the first valve lifter 32 to the inlet valves 17A via the first push rod 17C and the first rocker arm 17B. However, during operation, the first valve lifter 32 may rotate about the first axis A-A′ thereof within the first bore 16.
The second valve lifter 34 includes a second roller receiving portion 44 and a second roller 46 mounted on the second roller receiving portion 44. The second roller receiving portion 44 is an elongated member extending along the second axis B-B′. The second roller receiving portion 44 defines a second cavity 48 at a first end 50 thereof The second cavity 48 of the second roller receiving portion 44 receives the second roller 46. In particular, the second roller 46 is connected to the second roller receiving portion 44, via a bearing (not shown), such that the second roller 46 is rotatable about a second transverse axis D-D′ perpendicular to the first axis B-B′. The second roller 46 engages with a corresponding cam lobe 25 for actuating the exhaust valves 22 such that the rotational motion of the camshaft 23 causes reciprocating motion of the second valve lifter 34. Further, a second end (not shown) of the second valve lifter 34 engages with the second push rod for transferring the reciprocating motion of the second valve lifter 34 to the second push rod. In turn, the reciprocating motion is transferred through the second push rod and the second rocker arm to move the exhaust valves 22 between the open position and the closed position. However, during operation, the second valve lifter 34 may rotate about the second axis B-B′ thereof within the second bore 18.
FIG. 4 is an exploded view of the valve lifter assembly 26. The first valve lifter 32 is received through the first bore 16 of the cylinder head 14. Further, the first roller receiving portion 36 has a first inner face 52 and a first outer face 54 spaced apart from the first inner face 52. Similarly, the second valve lifter 34 is received within the second bore 18 of the cylinder head 14 along. The second valve lifter 34 is spaced apart from the first valve lifter 32 such that a space 56 is defined between the first valve lifter 32 and the second valve lifter 34. Further, the second roller receiving portion 44 has a second inner face 58 and a second outer face 60 spaced apart from the second inner face 58.
As shown in FIGS. 3 and 4, the valve lifter assembly 26 includes a spacer 62 positioned within the space 56 defined between the first valve lifter 32 and the second valve lifter 34. The spacer 62 is fastened to the underside 64 (see FIG. 3) of the cylinder head 14, via a first fastening member 66 and a second fastening member 68. The first fastening member 66 and the second fastening member 68 are adapted to engage with a first threaded opening 70 and a second threaded opening 72 of the cylinder head 14, respectively, to couple the spacer 62 with the cylinder head 14.
FIG. 5 is a perspective view of the spacer 62 of the valve lifter assembly 26. The spacer 62 includes a first surface 74 and a second surface 76 distal to the first surface 74. The second surface 76 abuts the underside 64 of the cylinder head 14. The second surface 76 defines a recess 78. The spacer 62 also includes a plurality of side surfaces 82 extending between the first surface 74 and the second surface 76. The side surfaces 82 include a front surface 84 and a rear surface 86. The front surface 84 and the rear surface 86 extend between the first surface 74 and the second surface 76 at a front end 88 and a rear end 90, respectively, of the first surface 74.
The side surfaces 82 include a pair of first bevel surfaces 92 extending between the first surface 74 and the second surface 76 at a first end 77 of the first surface 74. The pair of first bevel surfaces 92 includes a first front bevel surface 94 and a first rear bevel surface 96 distal to the first front bevel surface 94. The first front bevel surface 94 is positioned adjacent to the front end 88 of the first surface 74. The first front bevel surface 94 is adapted to provide a surface contact with the first inner face 52 of the first roller receiving portion 36, upon rotation of the first valve lifter 32. Further, the first rear bevel surface 96 is positioned adjacent to the rear end 90 of the first surface 74. The first rear bevel surface 96 is also adapted to provide a surface contact with the first inner face 52 of the first roller receiving portion 36, upon rotation of the first valve lifter 32.
The side surfaces 82 also include a first recessed surface 98 defined between the first front bevel surface 94 and the first rear bevel surface 96. The first recessed surface 98 has a first sectioned radius “R1”. The first recessed surface 98 defines a first clearance 100 (shown in FIG. 3) with the first inner face 52 of the first roller receiving portion 36 to receive lubrication oil therein.
The side surfaces 82 include a pair of second bevel surfaces 102 extending between the first surface 74 and the second surface 76 at a second end 103 of the first surface 74. The pair of second bevel surfaces 102 includes a second front bevel surface 104 and a second rear bevel surface 106 distal to the second front bevel surface 104. The second front bevel surface 104 is positioned adjacent to the front end 88. The second front bevel surface 104 is adapted to provide a surface contact with the second inner face 58 of the second roller receiving portion 44, upon rotation of the second valve lifter 34. Further, the second rear bevel surface 106 is positioned adjacent to the rear end 90 of the first surface 74. The second rear bevel surface 106 is adapted to provide a surface contact with the second inner face 58 of the second roller receiving portion 44.
The side surfaces 82 also include a second recessed surface 108 defined between the second front bevel surface 104 and the second rear bevel surface 106. The second recessed surface 108 has a second sectioned radius “R2”. The second recessed surface 108 defines a second clearance 110 (shown in FIG. 3) with the second inner face 58 of the second roller receiving portion 44 to receive lubrication oil therein.
The spacer 62 also includes a first hole 112 and a second hole 114 extending between the first surface 74 and the second surface 76. The first hole 112 receives the first fastening member 66 therethrough and the second hole 114 receives the second fastening member 68 therethrough to couple the spacer 62 with the cylinder head 14. In one example, the first hole 112 and the second hole 114 are through holes.
Referring to FIG. 6, a bottom perspective view of the valve lifter assembly 26 is illustrated. The spacer 62 is adapted to constrain rotation of the first valve lifter 32 and the second valve lifter 34 about the first axis A-A′ and the second axis B-B′, respectively, within a pre-defined angle range. During operation of the engine 10, the first clearance 100 defined between the first inner face 52 of the first roller receiving portion 36 and the spacer 62, the second clearance 110 defined between the second inner face 58 of the second roller receiving portion 44, and the spacer 62 constrain rotation of the first valve lifter 32 and the second valve lifter 34, respectively, within the pre-defined angle range.
As shown in FIG. 6, when the first valve lifter 32 is rotated about the first axis A-A′ in a first rotational direction ‘D1’ to a first position, the first inner face 52 of the first valve lifter 32 contacts the first rear bevel surface 96 of the spacer 62, thereby preventing further rotation of the first valve lifter 32 in the first rotational direction ‘D1’. Further, during operation of the engine 10, the first valve lifter 32 also rotates about the first axis A-A′ in a second rotational direction ‘D2’ opposite to the first rotational direction ‘D1’ to a second position (not shown). At the second position, the first inner face 52 of the first valve lifter 32 abuts the first front bevel surface 94 to constrain further rotation of the first valve lifter 32 in the second rotational direction ‘D2’. Therefore, the first valve lifter 32 is rotatable within the pre-defined angle range defined between the first position and the second position.
Similarly, as shown in FIG. 6, when the second valve lifter 34 is rotated about the second axis B-B′ in a third rotational direction ‘D3’ to a third position, the second inner face 58 of the second valve lifter 34 contacts the second rear bevel surface 106 of the spacer 62, thereby preventing further rotation of the second valve lifter 34 in the second rotational direction ‘D3’. Further, during operation of the engine 10, the second valve lifter 34 rotates about the second axis B-B′ in a fourth rotational direction ‘D4’ opposite to the first rotational direction ‘D3’ to a fourth position (not shown). At the fourth position, the second inner face 58 of the second valve lifter 34 abuts the second front bevel surface 104 to constrain further rotation of the second valve lifter 34 in the fourth rotational direction ‘D4’. Therefore, the second valve lifter 34 is rotatable within the pre-defined angle range defined between the third position and the fourth position.

INDUSTRIAL APPLICABILITY

The present disclosure is related to the valve lifter assembly 26 of the engine 10. The valve lifter assembly 26 includes the spacer 62 that constrains rotation of the first valve lifter 32 and the second valve lifter 34 about the first axis A-A′ and the second axis B-B′, respectively within the predefined angle range. Specifically, upon rotation of the first valve lifter 32 about the first axis A-A′, the first inner face 52 of the first valve lifter 32 contacts one of the pair of first bevel surfaces 92 to prevent further rotation of the first valve lifter 32. Also, upon rotation of the second valve lifter 34 about the second axis B-B′, the second inner face 58 of the second valve lifter 34 contacts one of the pair of second bevel surfaces 102 to prevent further rotation thereof. Thus, rotation of the first and second valve lifters 32, 34 about corresponding axes is constrained independently. Further, the pair of first bevel surfaces 92 and the pair of second bevel surfaces 102 provide surface contact with the first valve lifter 32 and the second valve lifter 34 during rotation thereof about corresponding axes. This reduces impact between the first and second valve lifters 32, 34 and the spacer 62. Furthermore, the first clearance 100 and the second clearance 110 receive lubrication oil therein, thereby causing minimal damage to the first and second valve lifters 32, 34.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

What is claimed is:

1. A valve lifter assembly coupled to a cylinder head of an engine, the valve lifter assembly comprising:

a first valve lifter received through a first bore of the cylinder head, the first valve lifter has a first axis, the first valve lifter includes a first roller receiving portion having a first inner face;

a second valve lifter received through a second bore of the cylinder head, the second valve lifter has a second axis, the second valve lifter includes a second roller receiving portion having a second inner face; and

a spacer coupled to an underside of the cylinder head and disposed between the first valve lifter and the second valve lifter, the spacer is adapted to constrain rotation of the first valve lifter about the first axis and the second valve lifter about the second axis, respectively, within a pre-defined angle range, the spacer including:

a first surface;

a second surface distal to the first surface, the second surface is adapted to abut the underside of the cylinder head;

a plurality of side surfaces extending between the first surface and the second surface, wherein the plurality of side surface includes:

a pair of first bevel surfaces adapted to provide a surface contact with the first inner face of the first roller receiving portion;

a first recessed surface defined between each of the pair of first bevel surfaces, wherein the pair of first bevel surfaces and the first recessed surface are adapted to define a first clearance with the first inner face of the first roller receiving portion to receive a lubricating oil therein;

a pair of second bevel surfaces adapted to provide a surface contact with the second inner face of the second roller receiving portion; and

a second recessed surface defined between each of the pair of second bevel surfaces, wherein the pair of second bevel surfaces and the second recessed surface are adapted to define a second clearance with the second inner face of the second roller receiving portion to receive the lubricating oil therein; and

at least one hole extending between the first surface and the second surface, the at least one hole is adapted to receive a fastening member therethrough to couple the spacer with the cylinder head,

wherein, during operation of the engine, the first clearance defined between the first inner face of the first roller receiving portion and the spacer, the second clearance defined between the second inner face of the second roller receiving portion, and the spacer constrain rotation of the first valve lifter and the second valve lifter, respectively, within the pre-defined angle range.