Patent Application
20090261286
The present disclosure is directed to a valve assembly and, more particularly, to a valve assembly having a washer.
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 '128 patent) issued to Mashinter. The '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 '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 '128 patent discloses that a washer having a tab may help secure the spring within the fuel injector.
Although the fuel injector of the '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.
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.
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
As illustrated in
As illustrated in
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
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.
