Patent Publication Number: US-2015059678-A1

Title: Cylinder head assembly with oil reflector for lubrication of a rocker arm

Description:
TECHNICAL FIELD OF INVENTION 
     The present invention relates to an internal combustion engine with a rocker arm for transmitting opening and closing motion from a camshaft to a combustion valve; more particularly to such an internal combustion engine with a rocker arm which is switchable between a high lift mode and a low lift mode; and even more particularly to such an internal combustion engine which includes an oil reflector for receiving a spray of oil and directing the spray of oil to a follower of the rocker arm. 
     BACKGROUND OF INVENTION 
     It is known in art of internal combustion engines to provide variable valve actuation devices which are switchable between a low lift mode and high lift mode, thereby opening a combustion valve, for example an intake valve, to a low lift and a high lift respectively. One such variable valve actuation device is disclosed in United States Patent Application Publication No. US 2009/0078225 to Hendriksma, hereinafter referred to as Hendriksma, the disclosure of which is incorporated herein by reference in its entirety. Hendriksma teaches a rocker arm with a rocker arm body within which is mounted a center high lift follower which is selectively allowed to pivot relative to the rocker arm body. A pair of low lift followers are mounted to the rocker arm body and flank the high lift follower. The high lift follower follows a high lift lobe of a camshaft to selectively transmit high valve lifting motion to a combustion valve while the low lift followers follow respective low lift lobes of the camshaft to selectively transmit low valve lifting motion to the combustion valve. 
     A latching mechanism is provided to selectively allow the high lift follower to pivot relative to the rocker arm body and to selectively prevent the high lift follower from pivoting relative to the rocker arm body. In order to position the latching mechanism to prevent the high lift follower from pivoting relative to the rocker arm body, thereby allowing high valve lifting motion to be transmitted to the combustion valve from the high lift lobe, pressurized oil is supplied to the latching mechanism. The pressurized oil urges a lock pin into engagement with the high lift follower. A spray hole is provided in the rocker arm body to allow some of the pressurized oil supplied to the latching mechanism to be sprayed onto the interface between the high lift follower and the high lift lobe, thereby lubricating the interface between the high lift follower and the high lift lobe. 
     Conversely, in order to position the latching mechanism to allow the high lift follower to pivot relative to the rocker arm body, thereby allowing low valve lifting motion to be transmitted to the combustion valve from the low lift lobes, oil is drained from the latching mechanism and a latch spring pushes the lock pin out of engagement with the high lift follower. Consequently, the high lift lobe causes the high lift follower to pivot cyclically within the rocker arm body. Since pressurized oil is not being supplied to the latching mechanism, oil is not sprayed onto interface between the high lift follower and the high lift lobe which may be acceptable in the low lift mode because the load between the high lift lobe and the high lift follower is relatively low. 
     The rocker arm of Hendriksma is considered to be a default low lift two-step rocker arm because the rocker arm is placed in the low lift mode when no pressurized oil is supplied to the latching mechanism. It is known to provide a two-step rocker arm similar to the rocker arm of Hendriksma with the exception of modifying the latching mechanism to place the rocker arm in the high lift mode when pressurized oil is not supplied to the latching mechanism, thereby resulting in a default high lift two-step rocker arm. Such a modified latching mechanism is disclosed in FIG. 2 of U.S. Pat. No. 7,761,217 to Waters et al., hereinafter referred to as Waters, the disclosure of which is incorporated herein by reference in its entirety. However, since pressurized oil is not used to place the latching mechanism in the high lift mode, pressurized oil is not available from the latching mechanism to lubricate the interface between the high lift lobe and the high lift follower. Consequently, an oil spray bar may be provided exclusively for lubricating the interface between the high lift lobe and the high lift follower. The addition of an oil spray bar exclusively for lubricating the interface between the high lift lobe and the high lift follower may add cost and complexity and may require an oil pump of increased capacity which may lead to decreased fuel efficiency of the internal combustion engine. 
     What is needed is an internal combustion engine which minimizes or eliminates one or more of the shortcomings as set forth above. 
     SUMMARY OF THE INVENTION 
     Briefly described a cylinder head assembly is provided for an internal combustion engine having a piston reciprocatable within a cylinder, a crankshaft rotated by the piston, a combustion chamber defined between the cylinder head assembly and the piston. The cylinder head assembly allows air into the combustion chamber and also allows exhaust gases out of the combustion chamber. The cylinder head assembly includes a cylinder head defining a port for selectively communicating the air to the combustion chamber or for selectively discharging the exhaust gases from the combustion chamber. The cylinder head also defines a valve seat between the port and the combustion chamber. A combustion valve is mounted in the cylinder head and is selectively seated and unseated with the valve seat. A camshaft mounted in the cylinder head is rotatable about a camshaft axis and has a high lift lobe and a low lift lobe. A rocker arm is engaged with the combustion valve and has a high lift follower and a low lift follower. The rocker arm is switchable between 1) a high lift mode for receiving high lift valve opening and closing motion from the high lift lobe of the camshaft and 2) a low lift mode for receiving low lift opening and closing motion from the low lift lobe of the camshaft, whereby rotation of the camshaft about the camshaft axis causes the rocker arm to pivot, thereby seating and unseating the combustion valve with the valve seat in a cyclic pattern. An oil spray source provides a spray of oil while an oil reflector is configured to receive the spray of oil and direct the spray of oil to one of the high lift follower and the low lift follower to provide lubrication between the interface of the high lift follower and the high lift lobe or between the interface of the low lift follower and the low lift lobe. 
     Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       This invention will be further described with reference to the accompanying drawings in which: 
         FIG. 1  is a schematic drawing of an internal combustion engine in accordance with the invention; 
         FIG. 2  is an elevation cross-sectional view of the internal combustion engine of 
         FIG. 1  taken through section line  2 - 2 ; 
         FIG. 2A  is an enlarged view of an intake valve and an intake valve seat of  FIG. 2  shown in the intake closed position; 
         FIG. 2B  is an enlarged view of the intake valve and the intake valve seat of  FIG. 2  shown in the intake open position; 
         FIG. 2C  is an enlarged view of an exhaust valve and an exhaust valve seat of  FIG. 2  shown in the exhaust closed position; 
         FIG. 2D  is an enlarged view of the exhaust valve and the exhaust valve seat of 
         FIG. 2  shown in the exhaust open position; 
         FIG. 3  is an elevation view of a camshaft bearing of the internal combustion engine in accordance with the invention; 
         FIG. 4  is a cross-sectional view of a rocker arm of the internal combustion engine in accordance with the invention; 
         FIG. 5  is an isometric view of an oil spray reflector of the internal combustion engine in accordance with the invention; 
         FIG. 6  is a cross-sectional view of the oil spray reflector of  FIG. 5 , now shown in conjunction with a portion of the internal combustion engine in accordance with the invention; and 
         FIG. 7  is an isometric view of an alternative oil spray reflector of the internal combustion engine in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     In accordance with a preferred embodiment of this invention and referring to  FIGS. 1 and 2 , an internal combustion engine  10  with an engine block  12  is shown. As shown, internal combustion engine  10  is a multi-cylinder engine, however, for brevity, only one cylinder  14  defined by engine block  12  and the components and features relating to cylinder  14  will be described since cylinder  14  is substantially the same as the others. A piston  16  is reciprocatable within cylinder  14  and a cylinder head assembly  18  is mounted to engine block  12  such that a combustion chamber  20  is defined between piston  16  and cylinder head assembly  18 . A fuel injector  22  may be provided for injecting fuel directly into combustion chamber  20  for combustion of the fuel within combustion chamber  20  which causes piston  16  to reciprocate within combustion chamber  20 . A lower end of piston  16  is attached to a crankshaft  24  which rotates about a crankshaft axis  26  as a result of reciprocation of piston  16  within combustion chamber  20 . Cylinder head assembly  18  selectively allows air into combustion chamber  20  to support combustion of the fuel and selectively allows exhaust gases out of combustion chamber  20  that result from the combustion of the fuel. Alternatively, but not shown, fuel injector  22  may inject fuel upstream of combustion chamber  20  such that the fuel is introduced into combustion chamber  20  along with air that is supplied by cylinder head assembly  18 . A spark plug (not shown) may be provided to initiate combustion of the fuel within combustion chamber  20 . Internal combustion engine  10  may be an in-line four cylinder engine as shown; however, it should be understood that a greater or lesser number of cylinders may be included and other cylinder arrangements may be used, for example only, an internal combustion engine having banks of cylinders arranged at an angle to each other which are commonly known as “V” configurations. 
     Cylinder head assembly  18  generally includes a cylinder head  28  fastened to engine block  12 ; an intake valve  30  mounted within cylinder head  28 ; an exhaust valve  32  mounted within cylinder head  28 ; an intake camshaft  34  mounted within cylinder head  28 ; an exhaust camshaft  36  mounted within cylinder head  28 ; an intake rocker arm  38  engaged with intake camshaft  34  and intake valve  30  and pivotable about an intake lash adjuster  39 ; an exhaust rocker arm  40  engaged with exhaust camshaft  36  and exhaust valve  32  and pivotable about an exhaust lash adjuster  41 ; and a valve cover  42  defining a cylinder head assembly compartment  44  with cylinder head  28  which encloses intake valve  30 , exhaust valve  32 , intake camshaft  34 , exhaust camshaft  36 , intake rocker arm  38 , intake lash adjuster  39 , exhaust rocker arm  40 , and exhaust lash adjuster  41 . Cylinder head assembly  18  will be described in greater detail in the paragraphs that follow. As illustrated, cylinder  14  includes respective pairs of exhaust valves  32 , intake rocker arms  38 , intake lash adjusters  39 , exhaust rocker arms  40 , and exhaust lash adjusters  41 ; however, it should be understood that each cylinder  14  may include different numbers of each depending on the design of internal combustion engine  10 . 
     Cylinder head  28  defines an air intake port  46  for selectively communicating air to combustion chamber  20 , an exhaust port  48  for selectively discharging exhaust gases from combustion chamber  20 , an intake valve seat  50  between air intake port  46  and combustion chamber  20 , and an exhaust valve seat  52  between exhaust port  48  and combustion chamber  20 . Intake valve  30  is selectively seated ( FIG. 2A ) and unseated ( FIG. 2B ) in a cyclic pattern with intake valve seat  50  via input from intake camshaft  34  and intake rocker arm  38  as will be discussed in greater detail below. Similarly, exhaust valve  32  is selectively seated ( FIG. 2C ) and unseated ( FIG. 2D ) in a cyclic pattern with exhaust valve seat  52  via input from exhaust camshaft  36  and exhaust rocker arm  40  as will be discussed in greater detail below. 
     With continued reference to  FIGS. 1 and 2  and now with additional reference to  FIG. 3 , intake camshaft  34  and exhaust camshaft  36  are mounted within cylinder head  28  via a plurality of camshaft bearings  54  which are each defined by a first semicircular recess  56  defined within cylinder head  28  and a second semicircular recess  58  formed in a bearing cap  60  which is secured to cylinder head  28  with fasteners illustrated as bearing cap bolts  62  which pass through bearing cap  60  and threadably engage cylinder head  28  to clamp bearing cap  60  to cylinder head  28 . In this way, intake camshaft  34  and exhaust camshaft  36  are captured between respective first semicircular recesses  56  and second semicircular recesses  58  such that intake camshaft  34  and exhaust camshaft  36  define journal bearing interfaces with respective camshaft bearings  54 . In this way, intake camshaft  34  rotates about an intake camshaft axis  64  and exhaust camshaft  36  rotates about an exhaust camshaft axis  66  via input from crankshaft  24  through a drive member (not shown), which may be, for example only, a chain, belt, or gear arrangement. 
     Again with reference to  FIGS. 1 and 2 , intake camshaft  34  includes a center high lift intake lobe  68  flanked by a pair of outer low lift intake lobes  70 . High lift intake lobe  68  selectively transmits a high lift valve opening and closing motion to intake valve  30  through intake rocker arm  38  as will be described in greater detail later while low lift intake lobes  70  selectively transmit a low lift valve opening and closing motion to intake valve  30  through intake rocker arm  38  as will also be described in greater detail later. The high lift valve opening and closing motion as used herein is meant to be a motion that will open intake valve  30  a greater magnitude from intake valve seat  50  than the low lift valve opening and closing motion. 
     Exhaust camshaft  36  includes an exhaust lobe  72  which transmits valve opening and closing motion to exhaust have 32 through exhaust rocker arm  40  as will be described in greater detail later. 
     With continued reference to  FIGS. 1 and 2  and now with additional reference to  FIG. 4 , intake rocker arm  38  includes an intake rocker arm body  74  within which is mounted a center high lift follower  76  which is selectively pivotable within intake rocker arm body  74  about a pivot shaft  78 . High lift follower  76  follows high lift intake lobe  68  of intake camshaft  34  in a sliding interface. A pair of low lift followers  80 , illustrated as rollers which flank high lift follower  76 , are mounted to intake rocker arm body  74  on a roller shaft  82 . Each low lift follower  80  follows a respective low lift intake lobe  70  of intake camshaft  34  in a rolling interface. A first end of intake rocker arm body  74  engages and pivots about intake lash adjuster  39  while a second end engages intake valve  30 , thereby causing intake valve  30  to seat and unseat with intake valve seat  50  as intake rocker arm  38  pivots about intake lash adjuster  39 . 
     A latching mechanism  84  is disposed within intake rocker arm body  74  at the end thereof which engages intake lash adjuster  39 . Latching mechanism  84  includes a latch bore  86  in intake rocker arm body  74  within which a latch pin  88  is slidably disposed. Latch pin  88  selectively engages high lift follower  76 , thereby preventing relative movement between high lift follower  76  and intake rocker arm body  74 . Latch pin  88  also selectively disengages high lift follower  76 , thereby allowing high lift follower  76  to pivot relative to intake rocker arm body  74  about pivot shaft  78 . A latch spring  90  urges latch pin  88  into engagement with high lift follower  76  when high lift of intake valve  30  is desired. Conversely, pressurized oil is supplied to latch pin  88  through an oil passage  89 , thereby compressing latch spring  90  and disengaging latch pin  88  from high lift follower  76  when low lift of intake valve  30  is desired. The supply of pressurized oil to latch pin  88  may be controlled, for example, by an oil control valve  92  which receives oil from an oil supply  94  of internal combustion engine  10 . 
     A lost motion spring  96 , illustrated for example only as a compression coil spring, is disposed operatively between high lift follower  76  and intake rocker arm body  74 . When latch pin  88  is disengaged from high lift follower  76 , lost motion spring  96  is compressed and uncompressed in a cyclic pattern by high lift intake lobe  68 . In this way, lost motion spring  96  maintains contact between high lift follower  76  and high lift intake lobe  68  while not permitting valve lifting motion to be transferred from high lift intake lobe  68  to intake valve  30 . 
     Further features and characteristics of intake rocker arm  38  are shown in United States Patent Application Publication No. 2009/0078225 to Hendriksma and U.S. Pat. No. 7,761,217 to Waters et al. which are incorporated herein by reference in their entirety. 
     Again with reference to  FIGS. 1 and 2 , exhaust rocker arm  40  includes an exhaust rocker arm body  98  within which an exhaust rocker arm follower  100  is mounted on roller shaft  101 . Exhaust rocker arm follower  100 , illustrated as a roller, follows exhaust lobe  72  of exhaust camshaft  36  in a rolling interface. A first end of exhaust rocker arm body  98  engages and pivots about exhaust lash adjuster  41  while a second end engages exhaust valve  32  thereby causing exhaust valve  32  to seat and unseat with exhaust valve seat  52  as exhaust rocker arm  40  pivots about exhaust lash adjuster  41  as a result of exhaust lobe  72 . 
     With continued reference to  FIGS. 1 and 2  and now with additional reference to  FIGS. 5 and 6 , cylinder head assembly  18  includes an oil reflector  102  which receives a spray of oil from an oil spray source and directs the spray of oil to high lift follower  76  in order to lubricate the interface between high lift intake lobe  68  and high lift follower  76 . Oil reflector  102  includes a mounting portion  104  for attaching oil reflector  102  to cylinder head assembly  18 . Mounting portion  104  may be substantially planar and may include mounting holes  106  for receiving bearing cap bolts  62  therethrough which clamp mounting portion  104  between the head of bearing cap bolts  62  and bearing cap  60 . Oil reflector  102  also includes at least one directing portion  108  extending from mounting portion  104  in the same direction as intake camshaft axis  64 . Directing portion  108  is substantially dome-shaped and includes a concave side  110  which generally faces toward intake rocker arm  38  and a convex side  112  which generally faces toward valve cover  42 . At least a portion of the spray of oil from the oil spray source is received by the concave side  110  and is directed by concave side  110  to impinge on high lift follower  76  to lubricate the sliding interface of high lift follower  76  and high lift intake lobe  68 . As shown, oil reflector  102  includes two directing portion  108  separated by mounting portion  104  such that oil reflector  102  serves to lubricate high lift followers  76  of two intake rocker arms  38  of cylinder  14 . Oil reflector  102  may be made of, for example only, sheet metal which is formed into the desired shape for example only by stamping, punching, and/or bending. While directing portion  108  is illustrated as substantially dome-shaped, it should be understood that directing portion  108  may be other shapes that are tailored to provide the desired lubrication of the interface of high lift follower  76  and high lift intake lobe  68 . 
     The oil spray source may be camshaft bearing  54 . The interface of camshaft bearing  54  and intake camshaft  34  is lubricated by oil from oil supply  94  through an oil gallery  114  ( FIG. 3 ) in cylinder head  28 . Oil from oil supply  94  is supplied to oil gallery  114  under pressure, for example, by a pump (not shown). The oil is then forced into the interface of camshaft bearing  54  and intake camshaft  34 . Oil from the interface of camshaft bearing  54  and intake camshaft  34  (journal bearing interface) is discharged therefrom to form the spray of oil which is received by the concave side  110  and is directed by concave side  110  to impinge on high lift follower  76  to lubricate the sliding interface of high lift follower  76  and high lift intake lobe  68 . In this way, the oil that is used to lubricate the interface of camshaft bearing  54  and intake camshaft  34  is also used to lubricate the interface of high lift follower  76  and high lift intake lobe  68 . Consequently, the pump used to pressurize oil from oil supply  94  does not need to be increased in size to accommodate an additional oil spray bar that would be used exclusively to lubricate the interface between high lift follower  76  and high lift intake lobe  68 . For clarity,  FIG. 6  includes arrows  116  to illustrate the spray of oil coming from camshaft bearing  54  and directed by oil reflector  102  to high lift follower  76 . 
     In order to lubricate high lift follower  76  of each intake rocker arm  38  for each cylinder  14 , an oil reflector  102  may be provided at each camshaft bearing  54  of intake camshaft  34 . Alternatively, and now with reference to  FIG. 7 , an oil reflector  102 ′ may be substituted for multiple oil reflectors  102 . Oil reflector  102 ′ includes mounting portions  104 ′ corresponding to each camshaft bearing  54  of intake camshaft  34 . Each mounting portion  104 ′ includes mounting holes  106 ′ for receiving bearing cap bolts  62  therethrough. Oil reflector  102 ′ also includes directing portions  108 ′ which each correspond to a respective intake rocker arm  38 . Oil reflector  102 ′ may perform substantially identical to multiple oil reflectors  102 ; however, fewer individual parts are needed and assembly of oil reflector  102 ′ may be simplified. 
     While exhaust rocker arm  40  has been illustrated as a conventional rocker arm which provides only one magnitude of lift, it should be understood that exhaust rocker arm  40  may be configured to be a two-step rocker arm as has been illustrated by intake rocker arm  38 . If exhaust rocker arm  40  is configured to be a two-step rocker arm, oil reflector  102  or oil reflector  102 ′ may be similarly utilized to lubricate exhaust rocker arm  40 . 
     While intake rocker arm  38  has been illustrated as defaulting to the high lift mode, i.e. high lift follower  76  is prevented from pivoting relative to intake rocker arm body  74 , it should now be understood that intake rocker arm  38  may be arranged to default to the low lift mode, i.e. high lift follower  76  is permitted to pivot relative to intake rocker arm body  74 . If intake rocker arm  38  is arranged to default to the low lift mode, a spray hole may be provided in intake rocker arm body  74  as disclose in United States Patent Application Publication No. 2009/0078225 to Hendriksma in order to lubricate high lift follower  76 . However, oil reflector  102  or oil reflector  102 ′ may still be used in order to provide supplemental lubrication high lift follower  76 . For example, high lift intake lobe  68  of intake camshaft  34  may mask a portion of high lift follower  76  from the oil spray provided by the spray hole. Oil reflector  102  may aid in lubricating the portion of high lift follower  76  that is masked by high lift intake lobe  68 . Furthermore, intake rocker arm  38  may be a conventional rocker arm which provides only one magnitude of lift similar to exhaust rocker arm  40  described above. If intake rocker arm  38  is a conventional rocker arm with only one follower, oil reflector  102  or oil reflector  102 ′ may be used in order to provide lubrication to the follower. 
     While oil reflector  102  and oil reflector  102 ′ have been illustrated as being mounted to cylinder head assembly  18  by securing oil reflector  102  and oil reflector  102 ′ to camshaft bearings  54 , it should be understood that other mounting arrangements may be contemplated. For example only, oil reflector  102  and oil reflector  102 ′ may alternatively be secured to valve cover  42 . Consequently, valve cover  42  and oil reflector  102  or oil reflector  102 ′ may be provided as a complete assembly to quicken the assembly process of internal combustion engine  10 . 
     While high lift follower  76  has been illustrated as being a sliding interface with high lift intake lobe  68 , it should now be understood that high lift follower  76  may alternatively be a rolling interface with high lift intake lobe  68 . Similarly, while low lift followers  80  have been illustrated as being a rolling interface with low lift intake lobes  70 , it should now be understood that low lift followers  80  may alternatively be a sliding interface with low lift intake lobes  70 . Consequently, oil reflector  102  or oil reflector  102 ′ may also/alternatively be used to lubricate the interface between low lift followers  80  and low lift intake lobes  70 . 
     While camshaft bearing  54  has been illustrated as the oil spray source for providing the spray of oil which is received and directed by oil reflector  102  or oil reflector  102 ′, it should now be understood that other oil spray sources may be utilized. For example only, an adjacent exhaust rocker arm  40  may provide a spray of oil which is received and directed by oil reflector  102  or oil reflector  102 ′. 
     While this invention has been described in terms of preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.