Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Nonmetallic element
Reexamination Certificate
1999-01-19
2001-04-17
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Nonmetallic element
C464S082000, C464S030000, C446S075000, C384S208000
Reexamination Certificate
active
06217453
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to torsional drive couplings. More particularly, the present invention is directed to a resilient torsional coupling including a resilient element.
BACKGROUND OF THE INVENTION
Flexible drive couplings are transmission devices that connect between a driving and driven member, such as in a drive train, to provide misalignment accommodation, torque carrying capability and appropriate stiffness for vibration isolation. Couplings are used, for example, in a drive train between an engine and a unit to be rotated, such as a jet drive unit in a personal watercraft or a propeller in a boat. The coupling's torsional stiffness is designed to minimize torsional vibrations that may cause damage to the drive train components. Moreover, such couplings, as taught in U.S. Pat. No. 4,516,956 to Staiert, and U.S. Pat. No. 4,041,730 to Kress may include a torque overload feature where the bonded member slips inside the housing after a limit torque is exceeded. This may occur, for example, when the driven component becomes jammed or when it strikes another object.
Further Prior Art couplings are shown in
FIGS. 1 and 2
. These coupling connect between a flywheel and a output shaft in a personal watercraft. Each coupling
10
includes a driving member
11
, a driven member
12
, and a elastomer member
13
positioned between them. The elastomer member
13
is bonded to the driven member
12
and is received in an interference fit (precompressed) and unbonded relationship in a pocket
14
formed in the driving member
11
. The
FIG. 1
Prior Art coupling includes a low cocking stiffness of about 14,400 lbf.-in./radian (1,627 N-m/radian). This low stiffness prevents any parallel or cocking misalignment between the members
11
,
12
from being converted into large radial forces which are then transmitted through engine mounts into the hull liner (frame), and finally to the operator of the personal watercraft. However, the
FIG. 1
coupling includes a low radial stiffness, about 56,200 lbf./in. (9,835 N/mm). Any rotational unbalance present will be aggravated at higher rotational frequencies because the unbalance tends to move further outward from the central axis because of the low radial spring rate. Moreover, the concentricity between the driving and driven member can be poor when a low radial stiffness is provided, thereby possibly further aggravating any unbalance present.
To combat the low radial stiffness, a pivot bearing
15
was added in the
FIG. 2
Prior Art coupling. This substantially increased the radial stiffness to approximately 219,000 lbf./in. (38,352 N/m), thereby improving any unbalance problem present. However, the positioning of the pivot bearing
15
is offset from the elastomer member
13
, therefore, any parallel or cocking misalignment between the members
11
,
12
causes the elastomer member to be loaded in radial compression. This results in a much higher cocking stiffness (approximately 426,700 lbf.-in./radian (48,217 N-m/radian)) than compared in the
FIG. 1
coupling, and, therefore, resultantly higher loads generated should any cocking or parallel misalignment be present. Moreover, because of the high cocking stiffness it may be necessary to shim various driveline components to minimized such cocking or parallel misalignment, thus increasing manufacturing costs.
Although, in general, these prior art couplings have adequate performance and/or durability, they each exhibit certain performance limitations. For example, the
FIG. 1
embodiment exhibits low radial stiffness thereby, in some installations, this can lead to unwanted radial vibrations in the drive train due to rotational unbalances in, and concentricity between, the members
11
,
12
. In an effort to provide increased radial stiffness, a pivot bearing
15
was added in the
FIG. 2
embodiment. However, this pivot bearing
15
limits the degree of cocking misalignment that is achievable by the coupling as well as substantially increases the cocking stiffness thereof.
Accordingly, there has been a long felt, and unmet need for a coupling capable of transmitting torques, which exhibits both increased radial stiffness as well as low cocking stiffness.
SUMMARY OF THE INVENTION
The present invention is a resilient coupling providing increased radial stiffness and at the same exhibiting a low cocking stiffness. Moreover, the coupling can accommodate substantial cocking and/or parallel misalignment. The coupling is most useful for transmitting torque, accommodating misalignment, and reducing vibration in the driveline components of personal watercraft.
According to the invention, the coupling comprises a driving member including an inner surface; a driven member including an outer surface; a flexible member intervening between the outer surface and the inner surface, the flexible member including an elastic center; and a pivot cooperating between the driving and driven members wherein an axial location of the pivot substantially coincides with an axial location of the elastic center.
According to another aspect of the invention, the coupling comprises a driving member including a bridging portion, an outer projection axially extending from said bridging portion, and an inner projection axially extending from said bridging portion and spaced radially inward from said outer projection, said outer projection including an inner surface and said inner projection including a first bearing member, a driven member including a main body portion including first and second projecting portions projecting axially therefrom, an outer surface formed on said first projecting portion and a second bearing member formed on said second projecting portion, a flexible member bonded to said outer surface of said driven member and received in a radially precompressed and unbonded relation with said inner surface, said elastomer member including an elastic center, and a pivot formed by said first and second bearing members, wherein an axial location of said pivot substantially coincides with said elastic center.
According to a further aspect of the invention, a coupling is provided comprising a first member including a generally hollow cylindrical outer projection having an inner surface, and an generally cylindrical inner projection concentric with said outer projection, said inner projection including a first bearing member, a second member including a generally cylindrical first projecting portion and a second projecting portion generally concentric with said first projecting portion, said first projecting portion including an outer surface and said second projecting portion including a second bearing member, an annular flexible member bonded to said outer surface and received in a radially precompressed and unbonded relation with said inner surface, said flexible member including an elastic center, and a pivot formed by said first and second bearing members, and wherein axial location of said pivot substantially coincides with an axial position of said elastic center.
In yet another aspect, a bonded subassembly is provided which is adapted to be received in the driving member of a coupling. The bonded subassembly comprises a driven member including first and second projecting portions extending in an axial direction from a main body portion of said driven member, said first projecting portion including an outer surface formed thereon, said second projecting portion including a bearing member formed on a radially outward surface thereof, a flexible member bonded to an outer surface, said flexible member including an elastic center (EC), a third projection which projects in a axial direction from a main body portion in a direction opposite from said projecting portions, and an axial location of said bearing member is substantially axially aligned with an axial position of said elastic center.
In accordance with another aspect, the invention comprises a vehicle, comprising a structure; an engine mounted to said structure; a drive component interconnected to and rotated by said engine; a cou
Browne Lynne H.
Dunwoody Aaron
Gnibus Michael M.
Lord Corporation
Wayland Randall S.
LandOfFree
Flexible coupling and bonded subassembly having a central... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flexible coupling and bonded subassembly having a central..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flexible coupling and bonded subassembly having a central... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2530429