Patent Publication Number: US-2016222834-A1

Title: Valve lifter assembly of engine

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 &#39;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 &#39;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  17 A received within the intake ports  15 , a first rocker arm  17 B connected to the inlet valves  17 A and a first push rod  17 C 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  17 A 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  17 A 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  17 A 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  17 A 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  17 A, 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  17 A 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  17 C for transferring the reciprocating motion of the first valve lifter  32  to the inlet valves  17 A via the first push rod  17 C and the first rocker arm  17 B. 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 “R 1 ”. 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 “R 2 ”. 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 ‘D 1 ’ 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 ‘D 1 ’. 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 ‘D 2 ’ opposite to the first rotational direction ‘D 1 ’ 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 ‘D 2 ’. 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 ‘D 3 ’ 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 ‘D 3 ’. Further, during operation of the engine  10 , the second valve lifter  34  rotates about the second axis B-B′ in a fourth rotational direction ‘D 4 ’ opposite to the first rotational direction ‘D 3 ’ 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 ‘D 4 ’. 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.