Patent Application
20100037848
Many gasoline and diesel cylinder head covers are isolated systems. The covers may be balanced between elastomeric isolator grommets and an elastomeric perimeter gasket. One approach to improve sealing capability is to increase the overall stiffness of the isolation system. However, increasing stiffness of the isolation system may increase Noise Vibration and Harshness (NVH) of the engine and/or cylinder head cover. Conversely, decreasing stiffness of the isolation system may increase the risk of oil leaks.
As one example compromise between sealing and stiffness, U.S. Pat. No. 6,371,073 to Billimack et al. discloses a cover member having a peripheral flange portion fixedly secured to an upstanding wall portion of an engine cylinder block. A sealing flange member is interposed between the peripheral flange and the upstanding wall portion. In addition, an isolation member, fabricated from an elastomeric material, is interposed between the sealing flange member and the peripheral flange. The three piece assembly, i.e. the peripheral flange portion, the isolation member, and the sealing flange member, is then secured to the upstanding wall portion with a plurality of bolts.
However, the inventors herein have recognized several issues with such an approach. As one example, the approach requires the addition of an upstanding wall portion to be added to the surface of the engine block, which may increase manufacturing costs, and affect the vibration characteristics of the engine block.
Thus, in one example, the above issues may be addressed by a cylinder head cover for an internal combustion engine wherein the sealing function and the NVH isolation function are decoupled from one another. The cylinder head cover may include a bottom carrier having a first end configured to be disposed in sealing engagement with a cylinder head. The bottom carrier may also have a second end. A cover body may be configured to provide a covering surface, and may have a side wall extending toward the cylinder head. A resilient joining element may connect the bottom carrier second end to an edge of the cover body side wall in sealing engagement.
The bottom carrier may serve to seal the cylinder head cover at a juncture between the cylinder head and the bottom carrier first end. By connecting the bottom carrier to the edge of the cover body at the second end of the bottom carrier, i.e. spaced from the first end, the sealing function and the NVH isolation function may be separated, and may be individually optimized. Further the joining member may serve to provide both a portion of the covering function of the cylinder head cover, and at least a portion of the NVH isolation functionality. In this way an efficient, and cost effective, structure may be provided.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
A valve cover for an internal combustion engine is described having spaced apart and/or separate sealing and NVH isolation functions. In this way each of the functions may be optimized.
In various embodiments, the perimeter of the cylinder head cover may be hard mounted to the cylinder head. This may enable a sealing gasket to be hard mounted onto the cylinder head. This may provided improved sealing performance. This may also enable a gasket with a smaller gasket cross-section to be used. The improved sealing performance may also enable larger fastener spans, and therefore fewer fasteners to be used.
In various embodiments the NVH isolation may be moved up the cover. This may enable the NVH isolation to be optimized, and therefore improved NVH performance. Embodiments may enable elimination of the elastomeric grommet, and the isolator sleeve that may be otherwise be required.
Referring now to
Combustion chamber 30 may receive intake air from an intake manifold 44, and may exhaust combustion gases via exhaust passage 48. Intake manifold 44 and exhaust passage 48 may selectively communicate with combustion chamber 30 via respective intake valve 52 and exhaust valve 54. In some embodiments, combustion chamber 30 may include one or more intake valves and/or one or more exhaust valves.
In this example, intake valve 52 and exhaust valves 54 may be controlled by cam actuation via respective cam actuation systems 51 and 53. Cam actuation systems 51 and 53 may each include one or more cams and may utilize one or more of cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT) and/or variable valve lift (VVL) systems that may be operated by the controller to vary valve operation. The position of intake valve 52 and exhaust valve 54 may be determined by position sensors 55 and 57, respectively. In alternative embodiments, intake valve 52 and/or exhaust valve 54 may be controlled by electric valve actuation. For example, cylinder 30 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including CPS and/or VCT systems.
Fuel injector 66 is shown coupled directly to combustion chamber 30 for injecting fuel directly therein in proportion to a pulse width of a signal that may be received from the controller. In this manner, fuel injector 66 provides what is known as direct injection of fuel into combustion chamber 30. The fuel injector 66 may be mounted in the side of the combustion chamber or in the top of the combustion chamber, for example. Fuel may be delivered to fuel injector 66 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some embodiments, combustion chamber 30 may alternatively or additionally include a fuel injector arranged in intake passage 44 in a configuration that provides what is known as port injection of fuel into the intake port upstream of combustion chamber 30.
Ignition system 88 may provide an ignition spark to combustion chamber 30 via spark plug 92 in response to a spark advance signal SA from the controller, under select operating modes. Though spark ignition components are shown, in some embodiments, combustion chamber 30 or one or more other combustion chambers of engine 10 may be operated in a compression ignition mode, with or without an ignition spark.
Cylinder head 94 may be coupled to a cylinder block 96. The cylinder head 94 may be configured to operatively house, and/or support, the intake valve(s) 52, the exhaust valve(s) 54, and the associated valve actuation systems 51 and 53 and the position sensors 55 and 57, and the like. Other components, such as spark plug 92 may also be housed and/or supported by the cylinder head 94. The cylinder block 96 may be configured to house the piston 36.
As described above,
The bottom carrier 102 may be configured to couple with and/or to partially house a gasket 115. The gasket 115 may be held adjacent the cylinder head 94 in sealing engagement with the cylinder head 94.
The joining element 112 may have a membranoid structure. A combination of the bottom carrier 102, the joining element 112, and the cover body 108 may form a substantially continuous seal over the cylinder head 94. The joining element 112 may provide at least some vibration isolation between the bottom carrier 102, and the cover body 108 at a spaced apart distance 120 from the bottom carrier first end 104. In this way the sealing features, for example the gasket 115 may be made a stiff as may be necessary to provide effective sealing properties, and the isolation features, for example the joining element 112 may be made as soft as may be necessary to provide effective NVH isolation properties.
The joining element 112 may span a spanning distance 123. In various embodiments the spanning distance 123 may be greater than the joining element thickness 122. In some embodiments the spanning distance 123 may be two or three or more times the joining element thickness 122.
The bottom carrier second end 106 may be bonded to the joining element 112 at a joining element first edge 130, and the cover body side wall 110 may be bonded to the joining element 112 at a joining element second edge 132. The bonding may be done via adhesives, welding, using fasteners, and the like.
In addition, or alternatively, one of the joining element second edge 132 and the side wall connecting edge 114 may have a second notched profile 138 and the other of the joining element second edge 132 and the side wall connecting edge 114 may have a second protrusion 140 configured to matingly fit within the notched profile 138.
As illustrated
Referring in particular to
Now, referring more specifically again to
With this system 200 the bottom carrier 102, the joining element 112, and the cover body 108 may collectively form a sealing cover over the cylinder head 94. The distance 120 from the first end 104 may be sufficient to include a sealing housing 142 that may be configured to provide for the sealing engagement and to provide for a stiffening structure. The stiffening structure may include a number of stiffening elements 144 spaced along a perimeter of the bottom carrier 102.
In various embodiments the sealing housing 142 may be configured to house a gasket 115 configured to provide the sealing engagement of the bottom carrier 102 with the cylinder head 94. The sealing housing 142 may include an inside wall 146 configured to extend from the cylinder head 94, and an outside wall 148 spaced from the inside wall 146, and disposed substantially parallel with the inside wall 146. A joining flange 150 may be configured to join the outside wall 148 to the inside wall 146. The extension portion 126 may be made substantially integrally with the inside wall 146 and may have an inside surface 152 disposed substantially coplanar with an inside surface 154 of the inside wall 146.
In various embodiments the cylinder head covering system 200 may further include one or more stiffening elements 144 extending from the joining flange 150 to the extension portion 126. In this way the stiffening elements 144 may provide additional strength to the bottom carrier 102, and may help provide a separation between the sealing function of the cylinder head covering system 200 and the NVH isolation function of the cylinder head covering system 200.
In various embodiments the cover body 108 may be made from a thermoplastic. In the same, or in other embodiments, the joining element 112 may be made from an elastomeric material. The joining element 112 may be integrated into the valve covering system 200 to provide at least a portion of the enclosing characteristics of the valve covering system 200.
Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts, operations, or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts may graphically represent code to be programmed into the computer readable storage medium in the engine control system.
It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.
The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.
