Method and apparatus for winding a return spring with a two piece rotor for a cam phaser

Abstract

A camshaft phaser, including: a drive sprocket; a stator; a rotor at least partially rotatable with the stator; a rotor extension fixedly connected to the rotor, having a slot at at least one outer circumferential position; a spring for biasing the rotor relative to the stator, having a first and a second end, the first end secured in the slot in the rotor extension and the second end secured on the stator.

Claims

1. A camshaft phaser comprising; a drive sprocket arranged to receive torque; a stator non-rotatably connected to the drive sprocket; a cover plate non-rotatably connected to the stator, having at least a first and a second post at a front portion of the cover plate; a rotor at least partially rotatable with respect to the stator and cover plate; a 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; and the second end of the spring secured on the first of the posts; wherein, in a first state the rotor plate is rotatable attached to the rotor and the rotor plate is rotated until the return spring is wound to a first torque value, and in a second state the rotor plate is non-rotatable attached to the rotor after the return spring is wound to the first torque value.

2. The phaser of claim 1, wherein the at least two posts are fasteners used to non-rotatably connect the cover plate to the stator.

3. The phaser of claim 2, wherein the spring extends from the first post around an outer surface of the second post prior to wrapping around the rotor plate.

4. The phaser of claim 1, wherein the coupling feature is comprised of at least two bolt holes for bolts extending through the phaser and securing the phaser to a camshaft of an engine.

5. 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.

6. The method of claim 5, further comprising a step of correlating number of rotations of the rotor extension to a torque value of the return spring.

7. The method of claim 6, wherein in the step of stopping the winding when a pre-determined torque value is reached, the step includes stopping the winding when the number of rotations of the rotor extension correlating to the torque value of the return spring is reached.

8. The phaser of claim 1, wherein the rotor plate has a substantially circular outer circumference.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) 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.

(2) FIG. 1A is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application;

(3) FIG. 1B is a perspective view of an object in the cylindrical coordinate system of FIG. 1A demonstrating spatial terminology used in the present application;

(4) FIG. 2 is a perspective exploded assembly view of a camshaft phaser according to one example embodiment.

(5) FIG. 3 is a perspective partial exploded assembly view of the camshaft phaser of FIG. 2.

(6) FIG. 4 is a front perspective assembly view of the camshaft phaser of FIG. 2.

(7) FIG. 5 is a front view of the camshaft phaser of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

(8) 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.

(9) 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.

(10) FIG. 1A is a perspective view of cylindrical coordinate system 80 demonstrating spatial terminology used in the present application. The present disclosure is at least partially described within the context of a cylindrical coordinate system. System 80 has a longitudinal axis 81, used as the reference for the directional and spatial terms that follow. The adjectives axial, radial, and circumferential are with respect to an orientation parallel to axis 81, radius 82 (which is orthogonal to axis 81), and circumference 83, respectively. The adjectives axial, radial and circumferential also are regarding orientation parallel to respective planes. To clarify the disposition of the various planes, objects 84, 85, and 86 are used. Surface 87 of object 84 forms an axial plane. That is, axis 81 forms a line along the surface. Surface 88 of object 85 forms a radial plane. That is, radius 82 forms a line along the surface. Surface 89 of object 86 forms a circumferential plane. That is, circumference 83 forms a line along the surface. As a further example, axial movement or disposition is parallel to axis 81, radial movement or disposition is parallel to radius 82, and circumferential movement or disposition is parallel to circumference 83. Rotation is with respect to axis 81.

(11) 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.

(12) FIG. 1B is a perspective view of object 90 in cylindrical coordinate system 80 of FIG. 1A demonstrating spatial terminology used in the present application. Cylindrical object 90 is representative of a cylindrical object in a cylindrical coordinate system and is not intended to limit the present invention in any manner. Object 90 includes axial surface 91, radial surface 92, and circumferential surface 93. Surface 91 is part of an axial plane, surface 92 is part of a radial plane, and surface 93 is a circumferential surface.

(13) FIG. 2 is a perspective exploded assembly view of camshaft phaser 100 according to one example embodiment.

(14) FIG. 3 is a perspective partial exploded assembly view of camshaft phaser 100 of FIG. 2.

(15) FIG. 4 is a front perspective assembly view of the camshaft phaser of FIG. 2.

(16) FIG. 5 is a front view of the camshaft phaser of FIG. 2. The following description should be viewed in light of FIGS. 2 through 5. Phaser 100 includes drive sprocket 104 arranged to receive torque; stator 108 non-rotatably connected to the drive sprocket; rotor 110 at least partially rotatable with respect to the stator and having radially aligned channels 112; and chambers 116 formed by the rotor and the stator, and open to (fed by) radially aligned channels 112. Rotor 110 includes vanes 126 and rotor plate mounting surface 150 for rotor plate or extension 130 non-rotatably connected to rotor 110. The terms rotor plate and rotor extension are used interchangeably in the following description.

(17) 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.

(18) Referring again to FIGS. 2 through 5, an exemplary method and apparatus is further described. Spring 136 is used to provide a default positioning force for rotor 110. Tab 138 formed at a first end of coil 164 of spring 136 is engaged with slot 140 in extension 130. Spring 136 includes spring coil 164, formed as a flat steel ribbon in this embodiment, wrapped around a circumferential surface of rotor plate 130, in consecutive expanding radial layers in the final assembled state, best shown in FIGS. 4 and 5. Semi circular securing contour 160 is formed at a second end of coil 164, at outer coil 164A of spring 136, and positioned to wrap around a radially outer circumferential surface 181 of securing bolt 144B. Outer coil 164A then extends tangentially from bolt 144B to wrap bolt 144A, an inner surface 170 of coil 164A contacting and wrapping around at least a portion of radially outer circumferential surface 180 of bolt 144A, forming wrap contour 162. In one embodiment, spring 136 is then wound using a tool (not shown) inserted into bolt clearance holes 185, holes 185 provided to allow fasteners (not shown) to extend through phaser 100 and secure phaser 100 to a camshaft of an internal combustion engine (not shown). It will be understood by one skilled in the art that alternate positions and methods of winding can be utilized without changing the scope of the present disclosure, including, but not limited to a single coupling feature on a front axial face of the rotor plate used to rotate the rotor plate. Once spring 136 is wound in consecutive radial layers as shown in FIGS. 4 and 5 and set to a predetermined torque value, as measured, for example, by a torque meter, fastener 146 is used to secure rotor plate 130 to rotor 110 and hold rotor assembly 190 (comprising rotor 110 and rotor plate 130) in a predetermined angular position relative to stator 108. Spring 136 is thus preloaded such that tab 138 urges plate 130 (and hence rotor 110 which is non-rotatably connected to plate 130 using fastener 146 in this embodiment) in rotational direction RD1.

(19) 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.

(20) 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.

(21) 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.

(22) 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.