Patent Application
20150053157
Example aspects described herein relate to camshaft phasers for varying the valve timing of an internal combustion engine. More particularly, the disclosed example embodiments relate to an apparatus and method to wind a return spring on a cam phaser with a two piece rotor.
Camshafts are used in internal combustion engines in order to actuate gas exchange valves. The camshaft in an internal combustion engine includes a plurality of cams that engage cam followers (i.e. bucket tappets, finger levers or rocker arms). When the camshaft rotates, the cams lift or depress the cam followers which in turn actuate gas exchange valves (intake, exhaust). The position and shape of the cams dictate the opening period and amplitude as well as the opening and closing time of the gas exchange valves.
Camshaft phasers are used to advance or retard the opening or closing period, phasing the camshaft with respect to the crankshaft rotation. Camshaft phasers generally comprise a timing gear, which can be a chain, belt or gear wheel connected in fixed rotation to a crankshaft by a chain, belt or gear drive, respectively, acting as an input to the phaser. The phaser includes an output connection to the camshaft. A phasing input is also provided in the form of a hydraulic, pneumatic or electric drive in order to phase or adjust the output rotation of the camshaft relative to the input rotation of the crankshaft.
Camshaft phasers are generally known in two forms, a piston-type phaser with an axially displaceable piston and a vane-type phaser with vanes that can be acted upon and pivoted in the circumferential direction. With either type, the camshaft phaser is fixedly mounted on the end of a camshaft. An example mounting may be performed as disclosed in U.S. Pat. No. 6,363,896, entitled “Camshaft Adjuster for Internal Combustion Engines”, by Wolfgang Speier, issued on Apr. 2, 2002, using a clamping screw forming the element of the camshaft phaser that effects centering relative to the camshaft.
Camshaft phasers that operate according to the vane-cell principle for use on single camshafts are known in the art. U.S. Pat. No. 6,805,080, entitled “Device for changing the control times of gas exchange valves of internal combustion engines, particularly rotary piston adjustment device for rotation angle adjustment of a camshaft relative to a crankshaft”, by Eduard Golovatai-Schmidt et al., issued on Oct. 19, 2004, generally shows a construction of a vane-cell type camshaft phaser for use in an internal combustion engine. These single camshaft phasers are commonly used on dual overhead cam (DOHC) engines where intake and exhaust cam lobes are located on separate intake and exhaust camshafts.
It is known to receive oil for chambers in a camshaft phaser, formed by a rotor and a stator for the phaser and used to control phasing of the phaser, in radially aligned channels opening to a radially central space. However, the requirement for a radially central space increases both the radial extent of the phaser and limits the spaces into which the phaser can be installed as well as the options for supplying oil to the chambers. With increasing engine sizes and decreasing space in engine compartments, axial and radial space is becoming limited, sometimes requiring multi-piece phaser assemblies in order to assemble a phaser in position. Commonly-owned co-pending patent application No. 61/824,033 discloses a phaser section including a stator non-rotatably connected to the drive sprocket, a rotor at least partially rotatable with respect to the stator and a rotor extension non-rotatably connected to the rotor, and a plurality of chambers formed by the rotor and the stator; and a rotor nose separately formed from the phaser section and non-rotatably connected to the phaser section, extending past a front side of the phaser section in a first axial direction. The rotor nose and rotor plate or extension are separately assembled and allow for assembly of the cam phaser assembly onto engines with restricted axial and radial space. U.S. patent application No. 61/824,033 is incorporated herein by reference.
U.S. Pat. No. 7,409,935 discloses a method and apparatus for setting a bias or return spring load during assembly of a camshaft phaser. A spring retainer is used with a first end of a bias spring engaged in a notch, the spring wrapped around the spring retainer and secured at a second end by an eccentric bolt or fastener. The spring is wound about the spring retainer and the spring retainer, in turn is secured to the rotor of the cam phaser. Where there is limited axial and radial space, such a separate component, such as a spring retainer can not be utilized. A method and apparatus for attaching and winding the return spring in a multi-piece phaser assembly is needed.
Certain terminology is used in the following description for convenience and descriptive purposes only, and is not intended to be limiting to the scope of the claims. The terminology includes the words specifically noted, derivatives thereof and words of similar import.
According to example aspects illustrated herein, there is provided a camshaft phaser, including a drive sprocket arranged to receive torque; a stator non-rotatably connected to the drive sprocket, a rotor at least partially rotatable with respect to the stator; a cover plate non-rotatably connected to the stator, having at least a first and a second post at a front face of the cover plate; a rotor plate non-rotatably connected to the rotor, the rotor plate having at least one slot at at least one circumferential position and at least one coupling feature for rotating the rotor plate; a return spring for biasing the rotor within the stator, the return spring having a first end and a second end; the first end of the spring secured into the slot; the second end of the spring secured on the stator; and the spring at least partially wrapped around a circumferential surface of the rotor plate.
According to example aspects illustrated herein, there is provided a method for assembling a return spring to a predetermined torque onto a camshaft phaser assembly, the method comprising the steps of fixing a first end of the return spring to a slot in a rotor extension; fixing a second end of the return spring to a stator; winding the return spring by rotating the rotor extension relative to the second end of the spring; stopping the winding when a pre-determined torque value is reached; and fixing the rotor extension to a rotor nested within the stator.
The above mentioned and other features and advantages of the embodiments described herein, and the manner of attaining them, will become apparent and be better understood by reference to the following description of at least one example embodiment in conjunction with the accompanying drawings. A brief description of those drawings now follows.
Identically labeled elements appearing in different ones of the figures refer to the same elements but may not be referenced in the description for all figures. The exemplification set out herein illustrates at least one embodiment, in at least one form, and such exemplification is not to be construed as limiting the scope of the claims in any manner. Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure.
The adverbs “axially,” “radially,” and “circumferentially” are with respect to an orientation parallel to axis 81, radius 82, or circumference 83, respectively. The adverbs “axially,” “radially,” and “circumferentially” also are regarding orientation parallel to respective planes.
In an example embodiment, seal plate 142 is used to seal chambers 116. In an example embodiment, bolt/bushing assembly 144 is used to non-rotatably connect plate 142, stator 108 and sprocket 104. Bolts 144 also are used to anchor spring 136. In an example embodiment, fastener/bushing 146 is used to non-rotatably connect plate 130 and rotor 110. In an example embodiment, locking pin assembly 148 is used to lock rotor 110 in a default position as is known in the art. It will be understood by one skilled in the art, that although bolts 144 are used in the present disclosure, any form of suitable fastener can be used.
Referring again to
In an alternative embodiment wrap bolt 144A and securing bolt 144B can be replaced by a wrap post and securing post located on an axially front, radially outer surface 118 of cover plate 142 or stator 108, designed for the same function as that described using bolts 144A and 144B.
In the foregoing description, example embodiments are described. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense. It will, however, be evident that various modifications and changes may be made thereto, without departing from the broader spirit and scope of the present invention.
In addition, it should be understood that the figures illustrated in the attachments, which highlight the functionality and advantages of the example embodiments, are presented for example purposes only. The architecture or construction of example embodiments described herein is sufficiently flexible and configurable, such that it may be utilized (and navigated) in ways other than that shown in the accompanying figures.
Although example embodiments have been described herein, many additional modifications and variations would be apparent to those skilled in the art. It is therefore to be understood that this invention may be practiced otherwise than as specifically described. Thus, the present example embodiments should be considered in all respects as illustrative and not restrictive.
| Number | Date | Country | |
|---|---|---|---|
| 61868605 | Aug 2013 | US |
