Patent Publication Number: US-9840944-B2

Title: Spring support and retention member for a camshaft phaser

Description:
FIELD OF INVENTION 
     The present invention relates to a support member, and, more particularly, to a spring support and retention member for a camshaft phaser. 
     BACKGROUND 
     Many camshaft phasers include a positioning spring that biases a rotor in a circumferential direction with respect to a stator by being connected at one end to the stator and at another end to the rotor. The positioning spring must be retained axially and radially during use in order to remain in its proper position within the camshaft phaser. 
     For example, U.S. Patent Application Publication No. 2009/0211549 discloses stop members for retaining a pair of spiral springs radially and a spring retention plate for retaining the springs axially. While this configuration retains the spiral spring in position, the use of a spring retention plate, separate from radial stop members, increases the number of components of the camshaft phaser, which increases cost. Further, the spring retention plate increases the size of the camshaft phaser. Due to space restrictions within an engine, it would be advantageous to minimize the size of the camshaft phaser. 
     Current configurations that do not include a spring retention plate, such as those that use press-fit nail-head pins, include other drawbacks. For example, such nail-head pins require an additional grinding operation in order to precisely size the nail-head pins so that they are reliably held in position when pressed in to the corresponding holes in the camshaft phaser housing. This additional grinding operation introduces additional cost and complexity to the assembly of the camshaft phaser. Furthermore, the nail-head pins are required to carry both bending and shear loads as they are positioned in apertures in the rotor and/or stator to retain the spring, and accordingly must be formed of a high strength, preferably steel, material to carry the loads, which makes the forming process more costly in comparison to straight steel pins, such as bearing needles, which have also been used for radial retention of such springs. 
     The present disclosure is directed to overcoming one or more problems of the prior art. 
     SUMMARY 
     In one aspect, the present disclosure is directed to a camshaft phaser. The camshaft phaser is positioned with respect to an axis of rotation. The camshaft phaser includes a stator configured to be non-rotatably connected to a drive wheel and a rotor at least partially rotatable with respect to the stator and configured to be non-rotatably connected to a camshaft. The rotor includes an aperture extending in a direction parallel to the axis of rotation. The camshaft phaser further includes a support member including a bushing including an elongated portion, a flange, and a through-bore extending through the elongated portion and the flange, and a cylindrical pin disposed in the through-bore and the aperture. The camshaft phaser also includes a positioning spring engaged with the support member and the stator to bias the rotor in a circumferential direction. 
     In another aspect, the present disclosure is directed to a method of assembling a camshaft phaser. The method includes inserting a cylindrical pin into a through-bore of a bushing and an aperture formed in a rotor such that the bushing is secured to the rotor. The method also includes engaging a positioning spring with the bushing and a stator of the camshaft phaser, thereby biasing the rotor in a circumferential direction with respect to the stator. The positioning spring is engaged with the bushing such that the positioning spring is retained radially and axially. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
       The foregoing Summary and the following detailed description will be better understood when read in conjunction with the appended drawings, which illustrate a preferred embodiment of the invention. In the drawings: 
         FIG. 1  is a perspective view of a camshaft phaser including a support member; 
         FIG. 2  is a perspective view of the camshaft phaser of  FIG. 1 , including an exploded view of the support member; 
         FIG. 3  is a cross-sectional view of a portion of the camshaft phaser of  FIGS. 1-2 , including the support member; and 
         FIG. 4  is another cross-sectional view of a portion of the camshaft phaser of  FIGS. 1-2 , including an alternative embodiment of the support member. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
       FIG. 1  shows an exemplary camshaft phaser  10  positioned with respect to an axis of rotation  100 . The camshaft phaser  10  includes a stator  12  configured to be non-rotatably connected to a drive wheel, such as a sprocket  14  or toothed pulley. The camshaft phaser  10  further includes a rotor  16  configured to be non-rotatably connected to a camshaft (not shown). The rotor  16  is at least partially rotatable with respect to the stator  12 . In this way, a camshaft may be selectively phased in order to alter a valve timing of an associated engine (e.g., in a manner known in the art). 
     The stator  12  includes a stator body and may further include one or more additional components. For example, the stator  12  may include one or more circumferentially extending hydraulic chambers, pressure plates and/or sealing plates non-rotatably connected to the stator body. The stator  12  further includes an opening  18  for receiving at least a portion of the rotor  16  therein. 
     The rotor  16  includes a rotor body and may further include one or more additional components. In one embodiment, the rotor  16  may include one or more components configured to cause the rotor  16  to rotate with respect to the stator  12 . For example, the rotor  16  may include vanes that extend into and divide the chambers in the stator as well as hydraulic components known in the art (e.g., solenoid valve, pin, spring, etc.) for causing the rotor  16  to rotate with respect to the stator  12 , for example by pressurizing one or both sides of the divided hydraulic chambers to cause the vane to move in one or the other circumferential directions or to be fixed in position. 
     The camshaft phaser  10  further includes a positioning spring  20 . The positioning spring  20  biases the rotor  16  in a circumferential direction toward an angular position with respect to the stator  12 . The rotor  16  is rotatable (e.g., via the hydraulic components described above) against the force of the positioning spring  20 . The positioning spring  20  includes a stator end  22  and a rotor end  24 . The stator end  22  is connected to the stator  12  and the rotor end  24  is connected to the rotor  16 . 
     The camshaft phaser  10  further includes a plurality of support members  26  configured to secure the positioning spring  20  to the stator  12  and/or the rotor  16 . The positioning spring  20  engages the support members  26  to bias the rotor  16  in the circumferential direction. For example, the support members  26  include one or more stator support members  28  configured to guide the spring and/or secure the stator end  22  to the stator  12  and one or more rotor support members  30  configured to guide the spring and/or secure the rotor end  24  to the rotor  16 . 
     In an exemplary embodiment, the positioning spring  20  includes a connection feature  32  at one or both of the stator end  22  or the rotor end  24  for securing the positioning spring  20  to a support member  26 . For example, the stator end  22  may include a first hook  34  configured to be placed around a selected stator support member  28  and the rotor end  24  may include a second hook  36  configured to be placed around a selected rotor support member  30 . 
     In an exemplary embodiment, at least one of the support members  26  is configured to radially and axially retain the positioning spring  20  on the stator  12  and/or rotor  16 . For example, at least the rotor support members  30  may include a bushing  38  configured to radially and axially retain the positioning spring  20  on the rotor  16 . 
     The bushing  38  includes an elongated portion  40  and a flange  42 . In an exemplary embodiment, the elongated portion  40  retains the positioning spring  20  radially. For example, the second hook  36  is placed around an exterior of the elongated portion  40  such that the positioning spring  20  is prevented from shifting in at least one radial direction. The flange  42  retains the positioning spring  20  axially. For example, the flange  42  extends over at least a portion of the positioning spring  20  such that at least a portion of the positioning spring  20  is prevented from shifting axially away from the rotor  16 . 
       FIG. 2  further illustrates the components of rotor support members  30 , which each include the bushing  38  and a cylindrical pin  44 . As shown in  FIG. 2 , the rotor  16  further includes an aperture  46  corresponding to the location of each of the rotor support members  30 . The aperture  46  extends in a direction parallel to the axis of rotation  100 . 
     The bushing  38  further includes a through-bore  48  extending through the elongated portion  40  and the flange  42 . Further, the elongated portion  40  and the flange  42  of the bushing  38  may be integrally formed as one piece. In an exemplary embodiment, the cylindrical pin  44  consists only of a solid cylinder (i.e., the cylindrical pin  44  does not include additional shapes and/or features). Preferably, this is made of steel, and can be, for example, a bearing needle that is precision ground to a precise size that allows for uniform assembly with an interference fit and sufficient strength to carry both shear and bending loads from the spring. 
       FIG. 3  illustrates a cross-sectional view of a portion of the camshaft phaser  10  that includes a rotor support member  30 . As shown, the bushing  38  is connected to the rotor  16  via the cylindrical pin  44  being positioned in the aperture  46 , preferably with an interference fit, and the through-bore  48 , preferably also with an interference fit. The bushing  38  is positioned entirely outside of the aperture  46  in the rotor  16 . 
     In an exemplary embodiment, the cylindrical pin  44  is formed with a diameter that is slightly larger than the diameters of the aperture  46  and the through-bore  48  such that the cylindrical pin  44  may be press-fit into the aperture  46  and through-bore  48  to connect the bushing  38  to the rotor  16 . It should be understood, however, that other configurations of the cylindrical pin  44  are possible. For example, adhesive, welding, threading, etc., may be used. 
     In order to secure the bushing  38  to the rotor  16 , the cylindrical pin  44  is inserted (e.g., press-fit) in the through-bore  48  and the aperture  46  such that the bushing  38  is secured to the rotor  16 . It should be understood that different sequences of steps for attaching the bushing  38  to the rotor  16  are possible. In one exemplary embodiment, the through-bore  48  is first aligned with the aperture  46  and the cylindrical pin  44  is inserted into the aligned aperture  46  and through-bore  48 . 
     In other embodiments, the cylindrical pin  44  may be preassembled with the bushing  38  or the rotor  16 . For example, in one embodiment, a first end of the cylindrical pin  44  is inserted into the through-bore  48  to form a bushing assembly. The bushing assembly is thereafter secured to the rotor  16  by inserting a second end of the cylindrical pin  44  that projects from the bushing  38  into the aperture  46 . In another exemplary embodiment, a first end of the cylindrical pin  44  is first inserted into the aperture  46  such that a second end of the cylindrical pin  44  projects from the rotor  16 . The bushing  38  is thereafter secured to the cylindrical pin  44  such that the second end of the cylindrical pin  44  is disposed in the through-bore  48 . 
     It should be understood that one or more of these disclosed methods may be used to attach the bushing  38  to an aperture  46  in the rotor  16  to form the rotor support members  30 , and/or to attach a bushing  38  to an aperture (not shown) in the stator  12  to form the stator support members  28 . After the bushing  38  is secured to the rotor  16  (and/or stator  12 ), the positioning spring  20  is positioned to engage the stator support members  28  and the rotor support members  30 . For example, the positioning spring  20  is positioned such that a first side contacts the elongated portion  40  and a second side contacts the flange  42 , thus radially and axially retaining at least a portion of the positioning spring  20  in position on the camshaft phaser  10 . 
       FIG. 4  illustrates another cross-sectional view of a portion of the camshaft phaser  10 , including a support member  26  according to an alternative embodiment. In the embodiment of  FIG. 4 , the support member  26  includes a bushing  38 A. The bushing  38 A is the same as the bushing  38 , except that the bushing  38 A additionally includes a base flange  50  positioned on an opposite end of the elongated portion  40  from the flange  42 . As shown in  FIG. 4 , the base flange  50  abuts a surface of the rotor  16 . The base flange  50  provides a supporting base to the bushing  38 , acting as a stop and helping to distribute any axial forces placed on the support member  26 . 
     The disclosed support member  26  is particularly applicable to retaining a positioning spring on a camshaft phaser, as described herein. The configuration of the support member  26 , including a separate bushing  38  and cylindrical pin  44 , provide several advantages. For example, the combination of the elongated portion  40  and flange  42  retains at least a portion of the positioning spring  20  radially and axially, thus removing the need for a separate spring retention plate and helping to minimize a size of the camshaft phaser  10 . Moreover, the use of the cylindrical pin  44 , which may be made inexpensively, to bear the load, helps to reduce cost as compared to headed pins that require an additional grinding operation. Further, because the bushing  38  is positioned entirely outside of the aperture  46 , it is not exposed to a shear force that may cause failure and allows the bushing  38  to be fabricated from a relatively inexpensive material, such as a lower grade steel, and with larger tolerances. 
     Having thus described the presently preferred embodiments in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the inventive concepts and principles embodied therein. It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. The present embodiments and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.