Abstract:
An oil control valve system according to one example of the present disclosure incorporates a common or interchangeable oil control valve at distinct locations of an engine to direct operation of switching mechanisms over sets of three cylinders. In another aspect of the present disclosure, four interchangeable oil control valves are used in a six-cylinder engine. Utilizing interchangeable oil control valves minimizes design costs, reduces assembly time, lessens repair or replacement burdens, and allows for enhanced engine performance.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of International Patent Application No. PCT/US2014/031991 filed on Mar. 27, 2014, which claims the benefit of U.S. Patent Application No. 61/807,553 filed on Apr. 2, 2013. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to oil control valve systems in engine systems. More particularly, the present disclosure relates to an oil control valve system having multiple occurrences of a common or interchangeable oil control valve that each provides a common output pressure to various engine-switching mechanisms. 
     BACKGROUND 
     Various systems have been developed for altering valve-lift characteristics for internal combustion engines. Such systems, commonly known as variable valve timing (VVT) or variable valve actuation (WA), improve fuel economy, reduce emissions, and improve driver comfort over a range of speeds. 
     SUMMARY 
     An oil control valve system according to one example of the present disclosure incorporates a common or interchangeable oil control valve at distinct locations of an engine to direct operation of switching mechanisms over sets of three cylinders. In another aspect of the present disclosure, four interchangeable oil control valves are used in a six-cylinder engine. Utilizing interchangeable oil control valves minimizes design costs, reduces assembly time, lessens repair or replacement burdens, and allows for enhanced engine performance. 
     An oil control valve configuration for an engine having first, second, third, fourth, fifth and sixth engine cylinders is disclosed. Each engine cylinder can have a first and a second intake valve in operable contact with a switching rocker arm. The oil control valve configuration can include a first, second, third and fourth oil control valve. The first oil control valve can be in operable pressure communication with switching mechanisms of a first and second switching rocker arm of the first engine cylinder, and a switching mechanism of a first switching rocker arm of the second cylinder. The second oil control valve can be in operable pressure communication with switching mechanisms of a first and second switching rocker arm of the third engine cylinder, and a switching mechanism of a second switching rocker arm of the second cylinder. 
     The third oil control valve can be in operable pressure communication with switching mechanisms of a first and second switching rocker arm of the fourth engine cylinder, and a switching mechanism of a first switching rocker arm of the fifth cylinder. The fourth oil control valve can be in operable pressure communication with switching mechanisms of a first and second switching rocker arm of the sixth engine cylinder, and a switching mechanism of a second switching rocker arm of the fifth cylinder. 
     The first, second, third and fourth oil control valves can each be configured to provide a common output pressure to a switching mechanism of each respective switching rocker arm for a predetermined input pressure. In one example, each of the first, second, third and fourth oil control valves are interchangeable. The first, second, third and fourth oil control valves can be common oil control valves relative to each other. 
     According to some implementations, the first and second intake valves attached to the first engine cylinder open from about 30 to about 300 crank angle degrees. The first and second intake valves attached to the second engine cylinder open from about 270 to about 540 crank angle degrees. The first and second intake valves attached to the third engine cylinder open from about 510 to about 60 crank angle degrees. The first and second intake valves attached to the fourth engine cylinder open from about 150 to about 420 crank angle degrees. The first and second intake valves attached to the fifth engine cylinder open from about 390 to about 660 crank angle degrees. The first and second intake valves attached to the sixth engine cylinder open from about 630 to about 180 crank angle degrees. Each oil control valve of the first, second, third and fourth oil control valves actuates a switching rocker arm associated with two distinct engine cylinders of the first, second, third, fourth, fifth and sixth engine cylinders. 
     In other examples, a first switching window for the first and second cylinders is open from about 275 to 30 crank angle degrees. A second switching window for the second and third cylinders is open from about 515 to 270 crank angle degrees. A switching window for the fourth and fifth cylinders is open from about 395 to 150 crank angle degrees. A switching window for the fifth and sixth cylinders is open from about 635 to 390 crank angle degrees. The first oil control valve actuates a switching rocker arm associated with the first and second cylinders throughout an engine combustion cycle. The second oil control valve actuates a switching rocker arm associated with the second and third cylinders throughout the engine combustion cycle. The third oil control valve actuates a switching rocker arm associated with the fourth and fifth cylinder throughout the engine combustion cycle. The fourth oil control valve actuates a switching rocker arm associated with the fifth and sixth cylinder throughout the engine combustion cycle. 
     According to additional features, an oil control valve system for an engine includes a first, second and third engine cylinder. Each cylinder has a first and second intake valve in operable contact with a switching rocker arm. The oil control valve system includes a first oil control valve and a second oil control valve. The first oil control valve is in operable pressure communication with switching mechanisms of a first and second switching rocker arm of the first engine cylinder and a switching mechanism of a first switching rocker arm of the second engine cylinder. The second oil control valve is in operable pressure communication with switching mechanisms of a first and second switching rocker arm of the third engine cylinder and a switching mechanism of a second switching rocker arm of the second engine cylinder. 
     In other features, the first and second oil control valves are each configured to provide a common output pressure to a switching mechanism of a switching rocker arm for a predetermined input pressure. The first and second oil control valves are interchangeable. The first and second oil control valves are common oil control valves relative to each other. The first and second oil control valves are opened for about 270 crank angle degrees. A switching window is delayed by about 5 crank angle degrees. A total switching window is about 480 crank angle degrees. 
     According to additional examples, a method for operating an oil control valve system fluidly coupled to a plurality of switching mechanisms provided in respective rocker arms of an engine is provided. The engine has a first, second and third cylinders. Each cylinder has a first and second intake valve that are actuated by respective first and second rocker arms. A first oil control valve is provided. The first oil control valve is in pressure communication with (i) the first rocker arm of the first cylinder, (ii) the second rocker arm of the first cylinder, and (iii) the first rocker arm of the second cylinder. A second oil control valve is provided. The second oil control valve is in pressure communication with (i) the first rocker arm of the third cylinder, (ii) the second rocker arm of the third cylinder, and (iii) the second rocker arm of the second cylinder. The first oil control valve is activated thereby actuating the first and second rocker arm of the first cylinder and the first rocker arm of the second cylinder. The second oil control valve is activated thereby actuating the first and second rocker arm of the third cylinder and the second rocker arm of the second cylinder. 
     In other features, the first oil control valve is activated to provide a first pressure at the first and second rocker arms of the first cylinder and the first rocker arm of the second cylinder. The second oil control valve is activated to provide a second pressure at the first and second rocker arms of the third cylinder and the second rocker arm of the second cylinder. The first and second pressures are substantially equivalent. 
     According to still other features, the engine further comprises a fourth, fifth and sixth cylinder. Each cylinder has a first and second intake valve that are actuated by respective first and second rocker arms. A third oil control valve is provided. The third oil control valve is in pressure communication with (i) the first rocker arm of the fourth cylinder, (ii) the second rocker arm of the fourth cylinder, and (iii) the first rocker arm of the fifth cylinder. A fourth oil control valve is provided. The fourth oil control valve is in pressure communication with (i) the first rocker arm of the sixth cylinder, (ii) the second rocker arm of the sixth cylinder, and (iii) the second rocker arm of the fifth cylinder. The third oil control valve is activated thereby actuating the first and second rocker arm of the fourth cylinder and the first rocker arm of the fifth cylinder. The fourth oil control valve is activated thereby actuating the first and second rocker arm of the sixth cylinder and the second rocker arm of the fifth cylinder. 
     In other features, the third oil control valve is activated to provide a third pressure at the first and second rocker arms of the fourth cylinder and the first rocker arm of the fifth cylinder. The fourth oil control valve is activated to provide a fourth pressure at the first and second rocker arms of the sixth cylinder and the second rocker arm of the fifth cylinder. The first, second, third and fourth pressures are substantially equivalent. The first and second intake valves attached to the first engine cylinder are opened from about 30 to 300 crank angle degrees. The first and second intake valves attached to the second engine cylinder are opened from about 270 to about 540 crank angle degrees. The first and second intake valves attached to the third engine cylinder are opened from about 510 to about 60 crank angle degrees. A switching rocker arm associated with the first, second and third cylinder is actuated throughout a combustion cycle of the engine. The first and second oil control valves are interchangeable. The first, second, third and fourth valves are interchangeable and common relative to each other. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a partial schematic diagram illustrating an oil control valve system constructed in accordance to one configuration of the present teachings and shown having one oil control valve communicating with three switching mechanisms; 
         FIG. 2  is a schematic diagram of the oil control valve of  FIG. 1  and shown in a closed position; 
         FIG. 3  is a schematic diagram of the oil control valve of  FIG. 2  and shown in an open position; 
         FIG. 4  is a detailed schematic diagram depicting an oil control valve system having four common oil control valves that each communicate oil to three switching mechanisms in a six cylinder engine; and 
         FIG. 5  is a graph demonstrating various valve-timing events and switching window periods in a high lift mode accordance with one example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     With initial reference to  FIG. 1 , an oil control valve system constructed in accordance to one example of the present teachings is shown and generally identified at reference numeral  10 . The oil control valve system  10  generally includes an oil control valve  12  that is in fluid communication with an engine oil supply  16 . In this regard, the oil control valve  12  is supplied oil from the engine oil supply  16 . The oil control valve  12  communicates oil to each of a first, second and third switching mechanism  20 ,  22  and  24  associated with a first, second and third switching rocker arm  30 ,  32  and  34 , respectively. In this regard, the oil control valve system  10  allows a single oil control valve  12  to regulate the flow of pressurized oil to the switching mechanisms  20 ,  22  and  24 . As will become appreciated from the following discussion, the oil control valve system  10  can be provided as multiple separate oil control valve systems that deliver oil to rocker arms on a single engine. Each oil control valve system  10  operates with a common or interchangeable oil control valve  12 . 
     With continued reference to  FIG. 1 , the switching rocker arm  30  will be briefly described. It will be appreciated that the configuration and function of the rocker arm  30  is merely exemplary and that the oil control valve system  10  can be suitable for other VVT or VVA configurations. For example, other valvetrain and rocker arm configurations suitable for accommodating the oil control valve system  10  may be found in commonly owned and co-pending U.S. Provisional Patent Application Ser. No. 61/722,765 entitled “DEVELOPMENT OF A SWITCHING ROLLER FINGER FOLLOWER FOR CYLINDER DEACTIVATION IN GASOLINE ENGINE APPLICATIONS”, the disclosure of which is fully incorporated herein. 
     While only the switching rocker arm  30  is shown in detail, the rocker arms  32  and  34  are constructed similarly. The switching rocker arm  30  can include a three lobed cam  40 , a lash adjuster  42 , a valve  44 , a spring  46  and a spring retainer  48 . The three lobed cam  40  has a first and a second high-lift lobe  50 ,  52  and a low lift lobe  54 . The switching rocker arm  30  has an outer arm  56  and an inner arm  58 . During operation, the high lift lobes  50 ,  52  contact the outer arm  56  while the low lift lobe  54  contacts the inner arm  58 . The lobes  50 ,  52  and  54  cause periodic downward movement of the outer arm  56  and the inner arm  58 . The downward motion is transferred to the valve  44  by the inner arm  58 , thereby opening the valve  44 . The switching mechanism  20  of the switching rocker arm  30  switches between a high lift mode and a low lift mode. It will be appreciated that the switching mechanisms  22  and  24  are configured similarly. Actuation of the switching mechanism  20  between the low and high lift modes results from pressurized oil communicated from the oil control valve  12 . In the particular example shown, the oil control valve  12  delivers oil at higher pressure to switch the switching mechanism  20  to a low lift mode. In one example, the switching mechanism  20  includes a latch assembly that selectively latches the inner arm and outer arms for concurrent movement. The switching rocker arm  30  then alters the intake valve opening and closing by varying the lift provided by the arm. Other configurations are contemplated. For example, while the above configuration is directed toward a default latched condition where oil is delivered to the switching mechanism  20  to change the operating state from latched to unlatched, the configuration may be reversed such that the default condition is unlatched where oil is delivered to the switching mechanism  20  to change the operating state from unlatched to latched. 
     In the high lift mode, the outer arm  56  is latched to the inner arm  58 . During engine operation, the high lift lobes  50 ,  52  periodically push the outer arm  56  downward. Because the outer arm  56  is latched to the inner arm  58 , the high lift motion is transferred from the outer arm  56  to the inner arm  58  and further to the valve  44 . 
     When the switching rocker arm  30  is in an unswitched mode, the outer arm  56  is not latched to the inner arm  58 , and so high lift movement exhibited by the outer arm  56  is not transferred to the inner arm  58 . Instead, the low lift lobe  54  contacts the inner arm  58  and generates low lift motion that is transferred to the valve  44 . When unlatched from the inner arm  58 , the outer arm  56  pivots about an axle  60 , but does not transfer motion to the valve  44 . Further explanation of the switching rocker arm  30  and related latch assembly may be found in commonly owned and co-pending U.S. Patent Application Publication No. 2011/0226208 entitled “SWITCHING ROCKER ARM”, the disclosure of which is fully incorporated herein. 
     With further reference now to  FIGS. 2 and 3 , additional features of the oil control valve  12  will be described. It will be appreciated by those skilled in the art that the depiction of the oil control valve  12  is merely exemplary and other configurations may be employed for delivering oil from the engine oil supply  16  to the respective switching mechanisms  20 ,  22  and  24  of the switching rocker arms  30 ,  32  and  34 , respectively. In general, the oil control valve  12  has a valve body  70  that defines a cavity  72 . The valve body defines a high pressure oil inlet  74  and an outlet  76 . In the example shown, the outlet  76  delivers oil to a primary oil delivery line  80  that separates into discrete oil delivery lines  82 ,  84  and  86 . The oil delivery lines  82 ,  84  and  86  fluidly connect to the switching mechanisms  20 ,  22  and  24 , respectively. A bypass oil line  88  can deliver a nominal oil pressure continuously to the respective switching mechanisms  20 ,  22  and  24  regardless of an operational state of the oil control valve  12 . The oil pressure provided by the bypass oil line  88  is insufficient to alter the switching mechanisms  20 ,  22  and  24 . 
     The oil control valve  12  includes a solenoid plunger  90  that actuates between a first position ( FIG. 2 ) and a second position ( FIG. 3 ). When the oil control valve  12  is in an “OFF” state, the high pressure oil inlet  74  is blocked by the solenoid plunger  90 . The respective switching mechanisms  20 ,  22  and  24  do not receive pressurized oil in this state.  FIG. 3  shows the oil control valve  12  in an “ON” state. In this state, the plunger  90  is withdrawn from the inlet  74 , allowing high pressure oil to flow from the inlet  74 , through the cavity  72  to the outlet  76 . The switching mechanisms  20 ,  22  and  24  receive pressurized oil in this state by way of respective oil delivery lines  82 ,  84  and  86 . 
     With continued reference to  FIGS. 1-3  and additional reference to  FIG. 4 , the oil control valve system  10  will be described in greater detail and implemented in an engine  100  having six cylinders numbered one to six. The engine  100  has two cylinder banks  102  and  104  with three cylinders in each cylinder bank. As shown, the oil control valve  12  delivers oil through oil delivery lines  82 ,  84  and  86  to the switching mechanisms  20 ,  24  and  26  of the respective switching rocker arms  30 ,  32  and  34 . 
     The engine  100  has intake valves numbered I X,Y  where X corresponds to the cylinder number and Y has the values 1 or 2, corresponding to the first or second valve. The intake valves I X,Y  selectively actuate to allow air to enter the combustion chambers of the cylinders. The engine  100  further includes exhaust valves numbered E X,Y  where X corresponds to the cylinder number and Y has the values 1 or 2, corresponding to the first or second valve. The exhaust valves E X,Y  selectively actuate to allow emissions to exit the combustion chambers of the cylinders. 
     The oil delivery lines  82 ,  84  and  86  allow the oil control valve  12  to maintain operable pressure communication with the respective switching mechanisms  20 ,  22  and  24  of the rocker arms  30 ,  32  and  34 . While the switching mechanisms  20 ,  22  and  24  are generally depicted as incorporated into the rocker arms  30 ,  32  and  34 , they may be incorporated into another feature such as a respective lash adjuster (see lash adjuster  42 ,  FIG. 1 ). Furthermore, while the instant description is specifically directed toward oil control valve systems for use with the intake valves, one skilled in the art will readily appreciate that a similar system may be used for use with the exhaust valves. 
     According to the present disclosure, the oil control valve system  10  is replicated as oil control valve system  110 ,  210  and  310 . In this regard, a second oil control valve  112  delivers oil through oil lines  182 ,  184  and  186  to switching mechanisms  120 ,  122  and  124  of respective switching rocker arms  130 ,  132  and  134 . Similarly, a third oil control valve  212  delivers oil through oil lines  282 ,  284  and  286  to switching mechanisms  220 ,  222  and  224  of respective switching rocker arms  230 ,  232  and  234 . Additionally, a fourth oil control valve  312  delivers oil through oil lines  382 ,  384  and  386  to switching mechanisms  320 ,  322  and  324  of respective switching rocker arms  330 ,  332  and  334 . In sum, each of the oil control valves  12 ,  112 ,  212  and  312  deliver oil to three of twelve switching rocker arms. Again, according to additional aspects of the present disclosure, interchangeable oil control valves can be similarly incorporated to facilitate opening of the exhaust valves. Moreover, while the engine  100  is shown with two engine banks  102  and  104 , the engine  100  may incorporate one, three or four banks. In an engine configuration having one engine bank, two common and interchangeable oil control valves would control six intake valves of three engine cylinders. 
       FIG. 5  is a graph illustrating valve-timing events and switching window periods for the engine  100  shown in  FIG. 4 . Briefly, a switching window can be generally defined as a crank angle window or time available to switch between the high lift mode and the low lift mode. As shown in  FIG. 5 , the intake valves I 1,1  and I 1,2  attached to the first cylinder open from about 30 to about 300 crank angle degrees. The intake valves I 2,1  and I 2,2  attached to the second cylinder open from about 270 to about 540 crank angle degrees. The intake valves I 3,1  and I 3,2  attached to the third cylinder open from about 510 to about 60 crank angle degrees. The intake valves I 4,1  and I 4,2  attached to the fourth cylinder open from about 150 to about 420 crank angle degrees. The intake valves I 5,1  and I 5,2  attached to the fifth cylinder open from about 390 to about 660 crank angle degrees. The intake valves I 6,1  and I 6,2  attached to the sixth cylinder open from about 630 to about 180 crank angle degrees. 
     A switching window for the first and second cylinders is open from about 275 to 30 crank angle degrees. The switching window for the second and third cylinders is open from about 515 to 270 crank angle degrees. The switching window for the fourth and fifth cylinders is open from about 395 to 150 crank angle degrees. The switching window for the fifth and sixth cylinders is open from about 635 to 390 crank angle degrees. 
     With continued reference to  FIG. 5 , the total switching window for the first and second cylinders is 475 crank angle degrees. Similarly, the total switching window for the second and third cylinders, fourth and fifth cylinders, and fifth and sixth cylinders is 475 degrees. The switching window for any given cylinder is limited only by the switching window lag needed to avoid critical shift. A brief description of critical shift will now be described. In prior art systems that switch between a high lift mode and a low lift mode, a latch may slip and become only partially engaged with the rocker arm during high lift mode without adversely affecting performance. However, if the latch slips further and becomes fully disengaged, a valve spring accelerates to cause an impact between a bearing and a cam shaft. Such a slip may be referred to as a critical shift. This improper impacting can cause engine strain, wear, and rounding of engine components. Repeated critical shifts can prevent an engine from operating reliably. 
     The switching windows shown in  FIG. 5  lag behind the opening of a valve to avoid delivering pressure to a rocker arm at an improper time in the combustion cycle. Such a lag avoids a critical shift in the engine, such as the critical shift described above. In the example provided, the switching window lags behind the opening of the intake valves by about five degrees. The oil control valve systems  10 ,  112 ,  212  and  312  shown in  FIG. 4  provides a maximized switching window across multiple cylinders (see also  FIG. 5 ), which in turn maximizes the opportunity to move a switching mechanism during a combustion cycle. This is desirable when the engine is operating at high speeds or low temperatures because an oil control valve has less time to move a switching mechanism at high speeds. At low temperatures, oil viscosity increases and switching time increases. As one example, an engine is considered to operate reliably when the total switching window for the engine system is about 480 crank angle degrees to about 715 crank angle degrees. This can be about five percent to about 50 percent more time to actuate a switching mechanism as compared with an oil control valve system using two different oil control valves among three cylinders. The increased window can improve cold weather or high speed performance. 
     As an engine cools, the viscosity of oil in the engine rises, causing the switching time to increase. The switching windows shown in  FIG. 5  allow the engine more time to actuate a switching mechanism, which enhances performance at cool temperatures or at high speeds. 
     As discussed in detail herein, the oil control valve system of the present disclosure requires only a single oil control valve configuration. Explained further, the oil control valves  12 ,  112 ,  212  and  312  are common relative to each other and interchangeable. Utilizing interchangeable oil control valves throughout the engine  100  minimizes time and cost associated with design and assembly. Accordingly, the oil control valves  12 ,  112 ,  212  and  312  can have consistent performance attributes. 
     The oil control valves applied in arrangements such as those shown in  FIG. 4  may also be interchangeable, such as a set of oil control valves sharing a common specification, such as would be shared by commonly manufactured parts of a particular part number. Common oil control valves will apply consistent pressure output to the engine cylinders when coupled to a given pressure source such as the engine oil supply  16 . The oil control valve configuration according to the present disclosure has two sets of two common oil control valves. Two oil control valves  12  and  112  are implemented on one engine bank  102 . Two oil control valves  212  and  312  are implemented on the other engine bank  104 . The configuration of the two oil control valves  212  and  312  is substantially symmetric to the two oil control valves  12  and  112 . 
     By incorporating four common or interchangeable valves  12 ,  112 ,  212  and  312  throughout the engine  100 , common valve characteristics can be realized. For example, common characteristics can include, steady state output pressure as a function of input pressure; valve opening/closing characteristics such as the speed of the opening or closing; any delay in opening or closing, and transient behaviors of oil flow on opening and closing of the valve. It will be appreciated that oil control valves having a different configuration than one another yet be within specifications for use according to aspects of the present disclosure. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.