Patent Application
20220127978
The present application relates to variable camshaft timing (VCT) assemblies and, more particularly, to deformable features on at least a portion of a VCT assembly.
Internal Combustion Engines (ICEs) include one or more camshafts that open and close intake/exhaust valves and are rotationally driven by a crankshaft via an endless loop, such as a chain. The camshafts have shaped lobes that open and close valves as the camshafts are rotated. The opening and closing of the valves is precisely controlled based on the angular position of the camshaft(s) relative to the angular position of the crankshaft. In the past, the angular position of the crankshaft was fixed relative to the angular position of the camshaft(s). However, the ability to change the angular position of the camshaft relative to the angular position of the crankshaft such that ignition timing is advanced or retarded can help increase engine performance in a variety of ways, such as by improving engine smoothness at low-operating temperatures or by increasing fuel efficiency. The ability of change the angular position of the camshaft relative to the angular position of the crankshaft is often referred to as variable camshaft timing (VCT).
VCT can be implemented in a variety of ways. For example, VCT can be implemented using devices such as camshaft phasers that are actuated electrically or hydraulically. With respect to hydraulically-actuated camshaft phasers, a stator receives a rotor having one or more vanes and the rotor rotates relative to the stator. The stator can include a camshaft sprocket that engages the endless loop and communicates rotational energy from a crankshaft sprocket that also engages the endless loop. The vane(s) can be received by chamber(s) formed in the stator so that a radially-outward end of the vane abuts a radially-inward facing surface of the chamber to divide the chamber(s) into an advancing chamber section and a retarding chamber section. Supplying fluid, such as engine oil, to one chamber section while permitting fluid to exit another chamber section can move the rotor in one angular direction relative to the stator. Various mechanisms exist for supplying this fluid. Creating and maintaining clearances between different components of the camshaft phaser help ensure that the phaser properly functions. For example, ensuring that proper tolerances exist between the rotor and the stator or the rotor and a cover can permit fluid to flow within an intended space and prevent binding of the rotor relative to the stator. However, creating these tolerances can involve significant resources.
In one implementation, a variable camshaft timing (VCT) assembly includes a rotor having a hub from which one or more vanes extend radially outwardly; and a stator having a stator cavity that receives the rotor and permits the rotor to rotate relative to the stator about an axis of rotation, wherein the stator includes a deformable extension that regulates a distance between the stator and another component of the VCT assembly.
In another implementation, a variable camshaft timing (VCT) assembly includes a rotor having a hub from which one or more vanes extend radially outwardly; a stator having a stator cavity that receives the rotor and permits the rotor to rotate relative to the stator about an axis of rotation, wherein the stator includes a deformable extension that regulates a distance between the stator and another component of the VCT assembly and an end plate extension that is configured to be mechanically deformed to join an end plate to the stator.
A variable camshaft timing (VCT) assembly, such as a camshaft phaser, can have a stator formed from a substrate that includes a deformable extension regulating a distance between the stator and another component of the assembly. The VCT assembly can be assembled from a rotor, the stator, and end plates, for instance. The distance or tolerances between these elements can be specified and controlled using a deformable extension located on the stator. As the stator is manufactured, the deformable extension can be created as part of the initial casting of the part. Later, the size of the deformable extension can be mechanically altered based on a tolerance value to control the distance between the stator and other elements of the VCT assembly, such as an axial face of the rotor, the end plate, or both. In the past, the stator and other elements of the VCT assembly have been manufactured and later machined to more carefully control the dimensions of the stator and other elements. But subsequent machining of VCT assembly parts involves time and expense and use of the deformable extension can reduce or eliminate machine processing of VCT assembly parts. Another, different part of the stator can also be mechanically deformed so as to cabin the end plate in between the stator and the deformable extension thereby creating a mechanical connection or joint between these elements. The term stator, included here in the specification, can be interpreted to include any component of the VCT assembly having the deformable extension and should not be limited to embodiments disclosed herein.
An implementation of a VCT assembly in the form of a hydraulically-controlled camshaft phaser 10 is shown in
The stator 14 can include a camshaft sprocket 26 on a radially-outer surface of the stator 14. The camshaft sprocket 26 can engage an endless loop, such as a chain, that also engages a crankshaft sprocket that transmits rotational force from the crankshaft to the stator 14. The rotor 12 can be positioned within the stator 14 to rotate relative to the stator 14 and angularly displace the rotor 12 relative to the stator 14 and change the phase of the camshaft relative to the crankshaft. The rotor 12 can be received within a stator cavity 28 formed within the stator 14 such that the vanes 20 extend into fluid chambers 24 formed within the stator cavity 28. The fluid chambers 24 are located radially-outwardly from the hub 18 such that each vane 20 can divide the fluid chamber 24 into an advancing chamber portion 30 and a retarding chamber portion 32. The rotor 12 can rotate about the axis of rotation (x) within the stator cavity 28 in response to fluid supplied to or exiting from the advancing or retarding chamber portions 30, 32 thereby changing the angular position of the camshaft relative to the angular position of the stator 14.
The stator 14 can be formed from a substrate in a mold to create an initial form that includes a deformable extension 34. The deformable extension 34 in this implementation can extend from an axial face of the stator 36 along the axis of rotation (x). The deformable extension 34 can create or define an axial distance 40 between the axial face of the stator 36 and an axial face of the rotor 40. The deformable extension 34 can create or define an axial distance between the axial face of the stator 36 and the end plate 16. In this implementation, the deformable extension 34 can follow a portion of the axial face of the stator 36 along the radially-outer surface of the stator 42 as well as following the contour of the fluid chambers 24. The stator 14 can be formed using a mold that includes the deformable extension 34 as part of the initial shape of the stator 14. In one implementation, powdered metal can be filled in the mold that includes the deformable extension 34. After applying heat to the powdered metal in the mold, the stator 14 can emerge from the mold as a metal substrate. In other implementations, a metal or metal alloy can be heated to a temperature at which it exists in a molten state and then applied to the mold. After cooling, the formed stator 14 can be removed from the mold.
After emerging from the mold, the deformable extension 34 exists at an initial axial length extending along the axis of rotation (x). The initial axial length may be the largest axial length. Depending on a desired distance between the stator 14 and other elements of the VCT assembly 10, force can be applied to the deformable extension 34 in a direction at least substantially toward the axial face of the stator 36 to reduce the axial length of the deformable extension 34. The amount and/or duration of the force can depend on the amount of change in axial length of the deformable extension 34 desired. In one implementation, the application of force on the deformable extension 34 can be accomplished using metal roll-forming techniques. After application of force on the deformable extension 34, a final axial length can be created. The length or magnitude of the deformable extension 34 at the final axial length can define the relative position of the axial face of the stator relative to the axial face of the rotor. The length or magnitude of the deformable extension 34 at the final axial length can also define the clearance between the end plate 16 and the axial face of the rotor 40.
The end plate 16 (shown in
Another implementation of a VCT assembly in the form of a hydraulically-controlled camshaft phaser 100 is shown in
The stator 14′ can be formed from a substrate in a mold to create an initial form that includes a deformable extension 34 and an end plate extension 46. The deformable extension 34 in this implementation can extend from the axial face of the stator 36 along the axis of rotation (x). The deformable extension 34 can create or define an axial distance 38 between the axial face of the stator 36 and an axial face of the rotor 40. The deformable extension 34 can create or define an axial distance between the axial face of the stator 14′ and an end plate 16. In this implementation, the deformable extension 34 can follow a portion of the axial face of the stator 36 along the radially-outer surface of the stator 42. In addition to the deformable extension 34, the stator 14′ can be formed with the end plate extension 46 that is later mechanically deformed to secure the end plate 16 to the stator 14′. The stator 14′ and the end plate 16 can include apertures 48 through which studs 50 can extend thereby preventing the rotation of the stator 14′ relative to the end plate 16.
The end plate extension 46 can be mechanically deformed to connect the end plate 16 to the stator 14′.
It is to be understood that the foregoing is a description of one or more embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.
As used in this specification and claims, the terms “e.g.,” “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
