Patent Publication Number: US-7900886-B2

Title: Valve assembly having a washer

Description:
TECHNICAL FIELD 
     The present disclosure is directed to a valve assembly and, more particularly, to a valve assembly having a washer. 
     BACKGROUND 
     Some engines such as, for example, diesel engines, rely on compression ignition, where fuel is injected into a combustion chamber after air has been compressed to cause substantially immediate combustion without requiring a sparkplug. Compression ignition engines typically include a common rail fuel injection system, directing pressurized fuel to individual fuel injectors for injection into the combustion chamber. The fuel injector may include a needle check valve assembly reciprocatingly disposed within a cylindrical bore. To inject fuel, the needle check valve assembly may be selectively moved to open a nozzle outlet, thereby allowing high pressure fuel to spray from a nozzle supply passageway into the associated combustion chamber. The needle check valve assembly is typically secured within the fuel injector by a load screw. 
     A significant amount of torque may be applied to the load screw to adequately secure the valve assembly within the fuel injector. However, the clearances associated with the valve assembly may be extremely small, e.g., on the order of micrometers. The torque required to secure the valve assembly may be large enough to cause a misalignment of the valve assembly components, resulting in malfunction or damage to the valve assembly. A common industry practice is to use lubricants on the valve assembly to prevent misalignment during torquing, but these lubricants may mix with fuel during operation of the fuel injector, which may lead to improper engine operation. 
     One attempt at providing a valve assembly that addresses these shortcomings is described in U.S. Pat. No. 2,530,128 (the &#39;128 patent) issued to Mashinter. The &#39;128 patent discloses a fuel injector for supplying fuel to a cylinder of an internal combustion engine. Fuel is supplied from an external fuel source under pressure to a first reservoir within the fuel injector. The &#39;128 patent discloses a ball and spring assembly to control the flow of fuel from the first reservoir to a second reservoir. The second reservoir has a valve assembly configured to provide fuel to a combustion chamber. The &#39;128 patent discloses that a washer having a tab may help secure the spring within the fuel injector. 
     Although the fuel injector of the &#39;128 patent may provide a method for providing fuel to a combustion chamber, it may fail to prevent and/or reduce misalignment of a fuel injector when a screw is tightened to secure a valve assembly within a fuel injector. 
     The present disclosure is directed to overcoming one or more of the shortcomings set forth above. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with one aspect, the present disclosure is directed toward a valve assembly. The valve assembly includes a housing having a first recess disposed on an interior surface of the housing and at least one valve-supporting element disposed within the housing. The valve assembly also includes a washer disposed within the housing, the washer having a first washer surface and a projection for transferring torque. The first washer surface abuts against a first valve-supporting element surface of the at least one valve-supporting element and the projection is received in the first recess. The valve assembly also includes a first fastener disposed within the housing and having a first fastener surface abutting against a second washer surface of the washer. 
     According to another aspect, the present disclosure is directed toward a method for assembling a fuel injector. The method includes inserting at least one plate into a body of the fuel injector and inserting a washer having a tab into the body. The method also includes selectively engaging a first surface of the washer with a first surface of the at least one plate and inserting the tab into a recess disposed on an interior surface of the body. The method further includes selectively threading a screw into threads disposed on the interior surface to selectively urge the at least one plate against an end wall of the body. The method also includes selectively transferring torque from the screw to the body by selectively engaging the tab with a surface of the recess. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a pictorial illustration of an exemplary disclosed fuel injector; 
         FIG. 2  is a cross-section illustration of the fuel injector of  FIG. 1 ; and 
         FIG. 3  is a pictorial illustration of an exemplary disclosed tab washer of the fuel injector of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     A machine such as, for example, a mobile machine that performs some type of operation associated with an industry such as mining, construction, farming, power generation, or transportation, may include an engine such as, for example, a four-stroke diesel engine or a gaseous fuel-powered engine. The engine may be a compression ignition engine and may include an engine block that at least partially defines a plurality of cylinders, a piston slidably disposed within each cylinder, and a cylinder head associated with each cylinder. The cylinder, piston, and cylinder head may form a combustion chamber. 
     The machine may also include a fuel system for delivering fuel to the engine. An exemplary fuel system may include components that cooperate to deliver injections of pressurized fuel into each combustion chamber. The fuel system may include a common rail fuel injection system for directing pressurized fuel to individual fuel injectors for injection into the combustion chamber. The fuel system may include a tank configured to hold a supply of fuel, and a fuel pumping arrangement configured to pressurize the fuel and direct the pressurized fuel to a plurality of fuel injectors  50 , shown in  FIG. 1 , by way of a common rail. Fuel injectors  50  may be disposed within the cylinder heads and may be fluidly connected to the common rail by a plurality of distribution lines. Each fuel injector  50  may be operable to inject an amount of pressurized fuel into an associated combustion chamber at predetermined timings, fuel pressures, and fuel flow rates. 
     As illustrated in  FIG. 1 , each fuel injector  50  may include a solenoid assembly  52 , a valve assembly  54 , a nozzle assembly  56 , an alignment pin  58 , and a quill cone  60 . Solenoid assembly  52  may be any suitable solenoid actuator known in the art for actuating valve assembly  54 . Solenoid assembly  52  may energize to displace components of valve assembly  54 . In an alternative embodiment, any other suitable actuator such as, for example, a piezo actuator may be used to actuate valve assembly  54 . Nozzle assembly  56  may include a needle check valve  57  configured to block and unblock fuel flow from fuel injector  50  into the combustion chamber. Alignment pin  58  may serve to align fuel injector  50  when it is inserted into the cylinder head. Quill cone  60  may be configured to receive a fuel quill for receiving fuel. 
     As illustrated in  FIG. 2 , a housing  62  of fuel injector  50  may be configured to receive valve assembly  54 . Valve assembly  54  may include valve-supporting elements such as a first plate  64 , a second plate  66 , a shim  68 , one or more fasteners  70 , and a valve  72 . First plate  64 , second plate  66 , and shim  68  may be configured to support valve  72  within housing  62 . First plate  64 , second plate  66 , and shim  68  may include bores aligned in a longitudinal direction of fuel injector  50  and may be configured to allow valve  72  to pass through plates  64  and  66  and shim  68 . First plate  64 , second plate  66 , and shim  68  may be dimensioned to fit snugly within housing  62 , substantially preventing displacement of valve  72  in directions other than a longitudinal direction of fuel injector  50 . Valve assembly  54  may also include guides (not shown) to maintain the longitudinal alignment of valve  72 . A thickness of shim  68  may be varied to ensure a snug fit in a longitudinal direction of fuel injector  50  of valve assembly  54  within housing  62 . Plates  64  and  66  and shim  68  may also include bores for receiving one or more fasteners  70 . Fastener  70  may be any suitable fastener in the art such as, for example, a screw. An end of each fastener  70  may be attached to housing  62  so that one or more fasteners  70  may retain plates  64  and  66  and shim  68  within housing  62 . Plates  64  and  66  and shim  68  may also include fuel drain lines in fluid connection with a drain line  85  of fuel injector  50 . It is contemplated that valve assembly  54  may block and unblock flow through fuel drain line  85 , thereby affecting a displacement of needle check valve  57  of nozzle assembly  56  to affect fuel injection as described below. 
     An end  74  of valve  72  may be connected to armature assembly  76  via a bolt  78 . Armature assembly  76  may include an armature  80  disposed within a recess  82  of housing  62 . Armature  80  may include a bore and may be attached to bolt  78  via the bore. Bolt  78  may be operably connected to solenoid assembly  52  so that solenoid assembly  52  may displace armature assembly  76  within recess  82  in a longitudinal direction of fuel injector  50 . Because bolt  78  may be connected to valve  72 , a displacement of armature assembly  76  may cause a longitudinal displacement of valve  72  within fuel injector  50 . A spring  84  may apply a force to bias armature assembly  76  in a first position, where armature  80  bears against a load screw  86 . Load screw  86  may include a recess configured to receive bolt  78  when armature  80  is in the first position. 
     Solenoid assembly  52  may energize to overcome the bias of spring  84  and cause armature  80  to displace from the first position to a second position within recess  82 . In the second position, armature  80  may bear against a solenoid housing  88  of solenoid assembly  52 . When armature  80  is in the first position, valve  72  may block drainage of fuel through valve assembly  54 . This blockage may cause an area of nozzle assembly  56  above needle check valve  57  to be pressurized, affecting needle check valve  57  to be urged against a valve seat of nozzle assembly  56 , effectively blocking the flow of fuel from fuel injector  50  into the combustion chamber. When armature  80  is in the second position, valve  72  may allow the drainage of fuel through valve assembly  54 . Allowing fuel to drain may cause an area of nozzle assembly  56  above needle check valve  57  to decrease to a pressure less than a pressure of an area of nozzle assembly  56  below needle check valve  57 . The pressure differential may cause needle check valve  57  to be urged away from the valve seat of nozzle assembly  56  and effectively allow the flow of fuel from fuel injector  50  into the combustion chamber. The displacements of armature assembly  76  and valve assembly  54  caused by solenoid assembly  52  may be relatively small such as, for example, 22 μm or less. It is contemplated that solenoid assembly  52 , valve assembly  54 , and armature assembly  76  may cooperate with needle check valve  57  of nozzle assembly  56  to block and unblock fuel flow into the combustion chamber. 
     Load screw  86  may serve to secure valve assembly  54  by tightening plates  64  and  66  and shim  68  against an end  87  of housing  62 . Load screw  86  may include a bore configured to allow valve  72  to pass through load screw  86 . An outside surface of load screw  86  may include threading  89  that may be received by threading of an interior surface of housing  62 . Load screw  86  may be torqued by any suitable tool known in the art, threading load screw  86  into housing  62  and thereby tightening first plate  64 , shim  68 , and second plate  66  against each other and end  87 . A washer  90  may be associated with load screw  86  and may be disposed between load screw  86  and first plate  64 . 
     Washer  90  may be a tab washer. Washer  90  may include a projection such as tab  92  that may be integral with washer  90 . A recess  94  may be disposed within an interior wall of housing  62  and may be configured to receive tab  92 . Tab  92  may protrude from a side of washer  90  and may have a slightly curved end configured to correspond to a curvature of housing  62 , so that tab  92  may fit within recess  94 . Recess  94  may be large enough to allow tab  92  to displace within recess  94  in a longitudinal and transverse circumferential direction of fuel injector  50 . In an exemplary embodiment provided as an illustration and not as a limitation, recess  94  may have a depth extending into housing  62  of 1.75±0.3 mm, a width extending in a transverse direction of fuel injector  50  of 4.00±0.5 mm, and a height extending in a longitudinal direction of fuel injector  50  of 2.00±0.3 mm. 
     As illustrated in  FIG. 3 , washer  90  may be substantially rectangular. Washer  90  may also be square, circular, or oval in shape. A surface  96  of load screw  86  may abut a surface  98  of washer  90 , and both surfaces may be smooth to reduce friction between surfaces  96  and  98 . Tab  92  may be configured to engage recess  94  to transfer forces between load screw  86  and housing  62 . Tab  92  may be initially inserted into recess  94  so that no side of tab  92  contacts a side of recess  94 . As load screw  86  is tightened, the torquing force may twist washer  90  so that tab  92  displaces transversely within recess  94 . A side of tab  92  may engage a side of recess  94 , substantially preventing further twisting of washer  90  and transferring additional torque as a bearing force between tab  92  and recess  94 . It is contemplated that washer  90  may transfer torque forces due to tightening load screw  86  into housing  62  via tab  92  and recess  94  to prevent and/or reduce the torque from twisting and thereby misaligning first plate  64  relative to second plate  66 . 
     INDUSTRIAL APPLICABILITY 
     Fuel injector  50  may provide a method for maintaining the alignment of valve assembly  54 . During torquing to secure valve assembly  54  within fuel injector  50 , washer  90  may transfer torque via tab  92  and recess  94  of housing  62 , thereby reducing and/or preventing misalignment of valve assembly  54 . Additionally, the alignment of fuel injector  50  may be maintained without the need for lubrication that may mix with fuel and cause an engine to malfunction. 
     Plates  64  and  66  and shim  68  of valve assembly  54  may be disposed within housing  62  of fuel injector  50 . Washer  90  may be disposed between first plate  64  and load screw  86 . Tab  92  of washer  90  may be inserted into recess  94  of housing  62 . Torque may be applied to load screw  86  by threading load screw  86  into the threading on the interior surface of housing  62 . As load screw  86  is threaded into housing  62 , load screw  86  may displace toward washer  90  and may bias plates  64  and  66  and shim  68  against end  87  and into a relatively tight fit within housing  62 . As torque is applied to thread load screw  86  into housing  62 , the torque may cause washer  90  to twist. As washer  90  twists, tab  92  may displace within recess  94  so that a side of tab  92  engages a side of recess  94 , thereby transferring torque to housing  62  via tab  92  and recess  94 . Because torque may be transferred to housing  62  via washer  90 , instead of to first plate  64 , twisting and misalignment of first plate  64  relative to shim  68  and second plate  66  may be reduced and/or prevented. 
     Because valve assembly  54  may be securely fastened within housing  62  via appropriate torquing of load screw  86 , while not causing misalignment, fuel injector  50  may properly operate to provide fuel to the combustion chamber. Proper alignment may allow valve  72  to block and unblock fuel drainage through valve assembly  54 , thereby affecting a displacement of needle check valve  57  of nozzle assembly  56  and allowing fuel injection into the combustion chamber. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed valve assembly. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.