ONE-WAY CLUTCH ASSEMBLY AND COUPLING MEMBER FOR THEREIN WHEREIN LOCKING MEMBER DYNAMICS WITH RESPECT TO STRUT LAYDOWN SPEED ARE ENHANCED

Abstract

A coupling member for an engageable coupling assembly includes a coupling face having at least one pocket. Each pocket is sized and shaped to receive and nominally retain a locking member that lays down in its pocket during an overrunning condition of the assembly at a laydown angular velocity of the coupling member about a rotational axis of the assembly. Each pocket has a pocket axis which is angled with respect to a normal to a centerline of the coupling member to improve locking member dynamics with regards to strut laydown speed during the overrunning condition.

Claims

1. A coupling member for an engageable coupling assembly, the coupling member having a centerline through a center of the coupling member, the coupling member comprising: a coupling face having at least one pocket, each pocket being sized and shaped to receive and nominally retain a locking member that lays down in its pocket during an overrunning condition of the assembly at a laydown angular velocity of the coupling member about a rotational axis of the assembly and wherein each pocket has a pocket axis which is angled with respect to a normal to the centerline to improve locking member dynamics with regards to strut laydown speed during the overrunning condition.

2. The coupling member as claimed in claim 1, wherein the pocket axis of each pocket is rotated outwardly or counter clockwise with respect to the normal.

3. The coupling member as claimed in claim 1, wherein the pocket axis of each pocket is rotated inwardly or clockwise with respect to the normal.

4. The coupling member as claimed in claim 1, wherein the coupling member is a pocket plate.

5. The coupling member as claimed in claim 1, wherein the locking member is a locking strut.

6. The coupling member as claimed in claim 1, wherein the coupling face is an annular coupling face.

7. The coupling member as claimed in claim 1, wherein the coupling face has a plurality of pockets, each of the pockets being sized and shaped to receive and nominally retain a corresponding locking member.

8. The coupling member as claimed in claim 1, wherein each pocket has a “T” shape.

9. The coupling member as claimed in claim 1, wherein each pocket has an inner recess for receiving a biasing spring and wherein each pocket is a spring pocket.

10. The coupling member as claimed in claim 6, wherein the annular coupling face is oriented to face axially along the rotational axis.

11. The coupling member as claimed in claim 1, wherein each pocket axis is angled with respect to the normal in a range of −5° to 10°.

12. A one-way clutch assembly having a central axis, the assembly comprising: an annular pocket plate having a centerline through the central axis, the pocket plate including an annular coupling face having a plurality of pockets spaced from each other about the central axis, each of the pockets being sized and shaped to receive and nominally retain a locking member that lays down in its pocket during an overrunning condition of the assembly at a laydown angular velocity of the pocket plate about the central axis and wherein each pocket has a pocket axis which is angled with respect to a normal to the centerline to improve locking member dynamics with regards to strut laydown speed during the overrunning condition; an annular notch plate that extends around the central axis and includes notches spaced from each other about the central axis; and a plurality of locking members received within the pockets.

13. The assembly as claimed in claim 12, wherein the pocket axis of each pocket is rotated outwardly or counter clockwise with respect to the normal.

14. The assembly as claimed in claim 12, wherein the pocket axis of each pocket is rotated inwardly or clockwise with respect to the normal.

15. The assembly as claimed in claim 12, wherein each of the locking members is a locking strut.

16. The assembly as claimed in claim 12, wherein each pocket has a “T” shape.

17. The assembly as claimed in claim 12, wherein each pocket has an inner recess for receiving a biasing spring and wherein each pocket is a spring pocket.

18. The assembly as claimed in claim 12, wherein the annular coupling face is oriented to face axially along the central axis.

19. The assembly as claimed in claim 12, wherein each pocket axis is angled with respect to the normal in a range of −5° to 10°.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0043] FIG. 1 is a schematic perspective view of a coupling member in the form of a pocket plate constructed in accordance with at least one embodiment of the present invention;

[0044] FIG. 2 is a top plan view of the pocket plate of FIG. 1 and showing different possible draft angles and pocket rotation axes for 12 different pockets of the pocket plate;

[0045] FIG. 3 is a view similar to the view of FIG. 1 except the struts tips are angled inwardly;

[0046] FIG. 4 is similar to the view of FIG. 2 but with the changes shown in FIG. 3;

[0047] FIG. 5 is a schematic perspective view of a second coupling member in the form of a notch plate for use with the pocket plate of FIG. 1 and showing notches rotated to correspond to rotated pockets of a pocket plate;

[0048] FIG. 6 is a top plan view of the notch plate of FIG. 5;

[0049] FIG. 7 is an enlarged view of the circled area of FIG. 6 to better show the angle of rotation of one of the notches;

[0050] FIG. 8 is a view, partially broken away, of a portion of a pocket plate and having a rotated strut (which is typically received and retained within a rotated pocket such as one of the rotated pockets of FIGS. 1 and 2);

[0051] FIG. 9 shows graphs of resultant moment on a strut versus pocket plate RPM for various pocket rotations at a constant draft angle; and

[0052] FIG. 10 shows graphs of resultant moment on a strut versus pocket plate RPM for various wall drafts and no pocket rotation.

DETAILED DESCRIPTION/EXAMPLE EMBODIMENTS

[0053] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0054] Besides the many previously described factors effecting the “laydown” or “lockdown” speed of a strut, the inventors of this application have discovered that “pocket rotation angle” (i.e. angle of the entire pocket (or the outer wall and inner pocket ear of the pocket) within the pocket plate) is another factor that affects laydown speed as shown in FIG. 9. Counter-clockwise (i.e. outward) pocket rotation lowers laydown speed for a rotating pocket plate thereby allowing or compensating for relatively large draft angles which allows lower manufacturing costs. Clockwise (i.e. inward), pocket rotation raises laydown speed as also shown in FIG. 9. The desired speed (i.e. RPM) at which struts laydown determines the clutches ability to engage. Therefore, if it is desired that the clutch engage at a relatively high speed (i.e. RPM), than inward pocket rotation would be used.

[0055] With the addition of a pocket rotation, the geometric composition of the strut and its pocket change, resulting in the generation of a new moment due to the centripetal force now acting on the strut. Centripetal force is the physical force causing the strut/lock wall dynamics as described herein. This new moment arises from the relative change of point of rotation about which the strut rises or descends.

[0056] Referring now to FIGS. 1 and 2, there is illustrated a coupling member, generally indicated at 10, for an engageable coupling assembly. The coupling member or pocket plate 10 has a centerline 20 through a center 16 of the coupling member 10. The coupling member 10 includes a coupling face 12 having at least one pocket and, preferably, a plurality of pockets 14 labeled pocket #1-2 in FIG. 2. Each of the pockets 14 has a different draft angle and pocket axis angle, Φ, for illustrative purposes. However, it is to be understood that preferably the pockets 14 have the same draft angle and the same pocket axis angle. Each pocket 14 is sized and shaped to receive and nominally retain a locking member such as a locking strut 15 (i.e. FIG. 8) that lays down in its pocket 14 during an overrunning condition of the assembly at a laydown angular velocity of the coupling member 14 about a rotational axis 16 of the assembly. Each pocket 14 has a pocket axis 17 (only shown for pocket #1 in FIG. 2) which is angled with respect to a normal 18 to the centerline 20 to improve locking member dynamics during the overrunning condition.

[0057] The pocket axis 17 of each pocket 14 is rotated outwardly or counter clockwise with respect to the normal as shown in FIG. 2.

[0058] The locking member 15 is preferably a locking strut.

[0059] The coupling face 12 is preferably an annular coupling face 12. The coupling face 12 has the plurality of pockets 14 and each pocket 14 has a “T” shape.

[0060] Each pocket 14 has an inner recess 24 (FIG. 8) for receiving a biasing spring (not shown) wherein each pocket 14 is a spring pocket.

[0061] The annular coupling face 12 is oriented to face axially along the rotational axis 16. Splines 22 are provided on the inner diameter of the plate 10 to transfer torque to or from the plate 10.

[0062] FIGS. 3 and 4 show a coupling member or pocket plate 10′ which is substantially identical to the pocket plate 10 of FIGS. 1 and 2 and, consequently, like parts have the same reference number but a single prime designation. The pocket plate 10′ is substantially identical to the pocket plate 10 except the pockets 14′ have an inward rotation. Each pocket 14′ of pocket plate 10′ has the same draft angle and the same magnitude of rotation as the corresponding pocket 14 in pocket plate 10. As previously mentioned, the pocket plate embodiment of FIGS. 3 and 4 (i.e. inward pocket rotation) is used when it is desired that the resulting clutch engage at a relatively high RPM as shown in FIG. 9.

[0063] Each pocket axis 17 is angled with respect to the normal 18 in a range of −5° to 10° as shown in FIG. 9.

[0064] A combination of the pocket plate 10 with a second coupling member 20 of FIGS. 5 and 6 and one or more locking struts 15 form a coupling or clutch assembly having the central axis 16.

[0065] The annular notch plate 30 extends around the central axis 16 and includes notches 34 spaced from each other about the central axis 16. The notches 34 are formed in a coupling face 32 of the notch plate 30. The notches 34 are angled Φ which corresponds to at least one of the angles Φ of the pocket plate 10 or −Φ when used with the pocket plate 10′.

[0066] The following equations relate to the previously described new moment on a strut due to centripetal force and other factors affecting laydown speed, wherein: [0067] Sm=Strut Moment [0068] M=strut mass [0069] R=pitch radius of strut [0070] W=angular velocity of pocket plate [0071] Sf=spring force [0072] Ls=distance between pocket lock up face and spring center [0073] Lo=distance between pocket lock up face and outer overrun face [0074] Ew=Ear width [0075] Θ=draft angle [0076] Φ=entire pocket (or, alternatively, outer wall and inner pocket ear of pocket) rotation angle [0077] Fc=coefficient of friction [0078] Pm=distance between strut pivot point to strut center of mass [0079] Bp=distance between back of strut to strut pivot point [0080] St=thickness of strut [0081] ε=front ear wall angle [0082] For angle Φ<0 (i.e. inward rotation)

Inward Strut Rotation (CW Pocket Rotation, strut tip towards ID (i.e. inner diameter of plate 10) Sm−Sf*Ls+((M*r*ŵ2*Cos(̂Φ))/(Cos(Θ)−Fc*Sin(Θ)))*(Sin(Θ)*(Pm+Bp)−Fc*Cos(Θ) *(Pm+Bp))+M*r*ŵ2*Sin(Φ)*St/2 [0083] For angle Φ>0 or, Φ=0) (no rotation or outward rotation)

Outward Strut Rotation (CCW Pocket Rotation, strut tip towards OD (i.e. outer diameter of plate 10) Sm=Sf*(Ls−Lo+Ew)+M*r*ŵ2*(Sin(Θ)*Cos(Θ)−Fc*(Cos(Θ))̂2)*(Pm)−M*r*ŵ2*Sin (Φ)*(St+(Fc*(Sin(ε)*(St−Tan(ε)*(Ew))+(Ew/Cos(ε)))−Cos(ε)*(St−Tan(ε)* (Ew))/(Fc*Sin(ε)−Cos(ε)+Fĉ2*Cos(ε)−Fc*Sin(ε))))

[0084] In summary, the inventors discovered that the orientation of a locking member or strut with respect to the normal of the centerline of the pocket plate has an effect on the dynamic characteristics with regards to strut laydown speed. Counter clockwise rotation of the pocket axis tends to decrease the speed at which the strut lays down, whereas clockwise rotation tends to increase the laydown speed.

[0085] Counter clockwise rotation of the pocket(s) (i.e. with strut tip(s) towards outer diameter of the clutch) can reduce the sensitivity to oil requirements as well as aid in manufacturability by opening functional dimensional tolerances. Counter-clockwise rotation of the pocket(s) tends to decrease the strut laydown speed. This has a tendency to increase the resilience of the clutch to low oil conditions which might otherwise increase strut instability.

[0086] Conversely, clockwise rotation of the pocket(s) (i.e. with strut tip(s) towards the inner diameter of the clutch) tends to increase the strut laydown speed. This can be beneficial in clutch applications wherein the struts are required to be active at higher speeds, such as a dynamic application in which the clutch is required to be able to engage at high pocket plate and notch plate speeds.

[0087] Based on the discoveries of the inventors, instead of having the orientation of pocket primary or pocket axis normal to a center line passing through MD, the inventors made the strut's primary or pocket axis differ by an angle normal to that of the plate's center line.

[0088] The previously described “strut instabilities” and the damage it causes relates to improper dynamics of the strut. The strut dynamics are engineered such that at certain conditions (usually identified by a pocket plate RPM range as shown in FIGS. 9 and 10) the strut is no longer able to rise and remains in the pocket, compressing its biasing spring for the duration it is seated within the pocket. When these dynamics are altered the strut is allowed to leave the pocket during inappropriate circumstances, the result is strut instability which manifests as a distinct sound and vibration emanating from the component, and ultimately leads to failure.

[0089] As shown in FIG. 9, rotation of the pockets significantly alters the strut dynamics of the clutches. Inward rotation of the pocket contributes to a moment that would tend to raise the strut from the pocket; conversely, an outward rotation tends to lower it, acting against the spring force.

[0090] The graphs of FIG. 9 shows that from the baseline laydown speed of 3000 RPM, a −4° rotated pocket increases this speed to nearly 4500 RPM, a 50% increase. Conversely, the laydown speed can be reduced from the baseline laydown speed by nearly 50% by adding a positive rotation angle as also shown in FIG. 9. This rotation angle improves strut dynamics.

[0091] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.