This invention relates to mechanical couplings which connect one rotatable member to another rotatable member and, more particularly, to mechanical couplings for interconnecting rotating members which may become misaligned with respect to one another.

It is often advantageous to interconnect a pair of rotatable members so that the devices to which the members are connected can be rotated at the same speed. By way of example, one of the members may be connected to a turbine while the other of the members is connected to an electric generator or to a pump which is driven by the turbine.

It has long been recognized that the mechanical coupling which interconnects these members must be able to accept a pair of members in which the individual members may be misaligned. At times, it may be extremely difficult to install the devices to which the members are connected so that the members are exactly aligned at the installation. Even where this alignment is obtained at installation, settling of the foundation supporting these devices, bearing wear, and heat generated during the operation of the devices or numerous other variables often cause the interconnected members to become misaligned.

The resulting misalignment can occur in any one or two or all three of the following manners: It can occur in "angular misalignment" wherein the axes of the two members intersect at an angle. It can also occur in "parallel offset" wherein the axes of the two members do not intersect at all. Or, it can occur in "axial movement" comprising expansion or contraction along the axis of the members.

It has been a continuing problem in the art to provide a flexible coupling which is sufficiently flexible to accept all types of misalignment, while still having sufficient torque carrying capacity to transmit the desired level of torque between the two coupled members, while remaining in dynamic balance throughout its operation and while still misaligned, not producing large forces or moments on interconnected devices. The problem has become more acute where the members are driven at relatively high speeds of revolution because of the resulting increase in the centrifugal forces on the couplings, and where the operating environment imposes limitations on the physical size of the flexible coupling.

Those skilled in the art have attempted to fill these needs by providing flexible couplings manufactured out of one or more stacked diaphragms. Generally, this type of coupling makes use of flat discs or diaphragms of steel or other metal which are connected between the pair of shafts to be coupled. In many of these couplings, the ^' diaphragms tend to flex between bolts, located around the inner and outer circumferences of the diaphragms to accommodate misalignment which normally are present. This then allows the shafts to remain interconnected in spite of the misalignment. Where the parallel offset type of misalignment is a factor to be considered, many of these diaphragm type couplings are used in a tandem coupling assembly. In this assembly, a pair of diaphragm type couplings is separated by a coupling shaft. Each of the shafts to be interconnected by the tandem assembly is attached to a separate one of these diaphragm couplings. The position of the coupling shaft floats between the interconnected shafts as the members themselves become misaligned. Flexible diaphragms must be laterally stiff enough to support the coupling shaft and prevent any unstable vibratory motion, while being flexible enough to accommodate the misalignment.

The tandem coupling assembly has another advantage. Often, the devices from which the rotating members protrude such as turbines, pumps, and generators, have associated equipment including piping, gages, and the like, mounted near the ends of the rotating members. Thus, it is difficult to mount two such devices close together. The coupling shaft of the tandem coupling assembly can be provided in various lengths to accommodate the required distances between the rotating members of two such devices. Furthermore, by providing a coupling shaft of sufficient length, bearings and seals used with the devices can be removed by disconnecting the coupling shaft and removing these through the resulting opening, rather than by dismantling the devices.

Many of these prior art diaphragm type couplings have been used with a great deal of satisfaction for numerous industrial and commercial applications. However, further state of the art industrial improvements have required the operation of these couplings at higher speeds and for the transmission of increasing torque levels. Furthermore, there is a demand to provide couplings having the capability of accepting larger shaft misalignment', including increased parallel offset, increased angular misalignment, as well as increased axial movement. Couplings must accept the increased misalignment without producing significant forces and moments back to the devices to which the coupled rotating members are connected. Such forces and moments can cause these devices to have increased wear and, thus, have increased maintenance requirements or potential failure. Such forces and moments can also contribute to serious deleterious vibrational effects of the interconnected rotating members.

Furthermore, a need has arisen for couplings which will meet the increased performance demands and will fit into smaller spaces. It is still a further object of this invention to provide a flexible, diaphragm type coupling for use in a tandem coupling assembly which provides for increased misalignment of the interconnected shafts, while avoiding the development of high levels of stress within the coupling diaphragms.

In Anderson, United States Patent No. 3,808,837, the applicant provided a flexible diaphragm type coupling that transmits torque through a plurality of flexible diaphragms held apart by separate incompressible fillers to support the flexing areas apart to prevent contact between flexure points. The Anderson Patent, has provided to be proven extremely satisfactory in typical industry service. However, under extreme conditions of required flexibility or diameter restriction, the filler edge will contact the outside and highly stressed inside diameter of the diaphragm flex area, producing fretting and unsatisfactory service life.

Increasing the thickness of the separate filler approximately beyond 1.5 times the- flexible portion thickness to allow for a greater filler radius to reduce fretting or increases spacing by other means can produce an unacceptable stress in the outer diaphragms , since the further a diaphragm is from the center of the pack, the more it must bend at a given angular misalignment. Separation with elastomers, which would minimize fretting, is unsuccessful under high performance conditions since clamping loads and centrifugal forces will cause the elastomer to extrude from between the diaphragm surfaces. Increasing the flex area beyond certain limits is also not satisfactory, since the diaphragms become unstable and buckle under torque or exceed diameter restrictions.

Other previous inventions cannot sustain a single diaphragm failure and maintain mechanical stability under torque, misalignment and speed since the diaphragms are attached in series, unless a cumbersome back-up device is included in the design.

STATEMENT OF THE INVENTION Briefly stated, and in accordance with one aspect of this invention, a flexible diaphragm member is provided for use in a flexible coupling assembly. In this assembly, a first rotatable member is connected to a second rotatable member through the use of a pair of diaphragm type flexible coupling members which are separated by a coupling shaft. Each of the rotatable members is attached to a separate one of the flexible coupling members in this type of an assembly. In the flexible coupling member, the torque is transmitted through a plurality of circular diaphragms. Each of these diaphragms has at least one and no more than about four circumferentially extending convolutions, each of these convolutions being identical in shape and identical in position on its respective diaphragm with respect to a corresponding convolution on the other diaphragms. Inner and outer clamping parts are used to secure the diaphragms in a stacked con iguration to form a pack or flexible coupling member. Inner and outer separating or filler portions are provided along the inner and outer periphery of each diaphragm. The filler portions extend along both sides of each diaphragm member in the stack to support and separate them in place. The diaphragms are held in place along their filler portions by inner and outer clamping parts. The clamping parts are secured together by holding means such as bolts. The filler portions are generally coextensive with the clamping parts, and are as thick or thicker in cross section than the flexible convoluted nortion, thus providing integral incompressible spacing

means, to prevent the diaphragms from contacting one another during the operation of the flexible coupling member. Neither the spacing means nor any other solid extends into the space between the convolutions of adjacent diaphragms. Thus, when the diaphragms are flexed in the area containing the convolutions, surface damage from contacting flexure points of the convolution is avoided.

The integral filler design allows the separation of the diaphragms to be minimal which stiffens the assembly laterally allowing for higher rotational speeds without damaging vibration, higher misalignment capability at a smaller diameter than the previous Anderson et al design. Since all flexure contact points are eliminated including the transition point and the diaphragms are assembled in parallel, mechanical stability will be present when properly designed with single and even multiple diaphragm failures. This produces a design of substantially smaller diameter, lighter weight and a built-in fail safe feature for reliability and life which is particularly suited for extreme conditions such as aircraft applications or critical industrial applications. By attaching the diaphragms in parallel, rather than in series, this invention can sustain diaphragm failures and maintain mechanical stability under torque, misalignment and speed.

Substantially improved performance has been obtained where the size of the flexing area is such that the ratio of the radius of the inside circumference of the flexing area is less than approximately six-tenths. A particularly advantageous size flexing area comprises one in which the ratio of the radius of the inside circumference to that of the radius of the outside circum erence of the flexing area is between about four-tenths and about six-tenths. Where the convolution in the flexing area consist of a pair of convolutions forming an S-shape, substantially improved performance is obtained when the product of the thickness of

a diaphragm (h) expressed in inches, and the peak-to-peak height of the two convolutions (s), measured at the center lines of the diaphragm material and also expressed in inches, is greater than about 0.0015 and less than about 0.0035.

Each diaphragm member comprises a single member having an annular flexible convoluted portion, an integral annular inner clamping or filler portion defining about its inner periphery, a hole, an integral annular outer clamping or filler portion defined about its outer periphery. The inner and outer filler portions being uniform thickness and being thicker in cross section than the flexible convoluted portion. An annular inner transition portion extends between the flexible convoluted portion and the annular inner filler portion provides a smooth transition from the thicker inner filler portion to the flexible convoluted portion. An outer transition portion is provided between the flexible convoluted portion and the outer filler portion and provides a smooth transition from the outer filler portion to the flexible convoluted portion. The inner and outer filler portions are defined by two flat parallel sides which permit the diaphragm members to be stacked with the outer filler portions resting on one another and the inner filler portions resting on one another and the flexible convoluted portions being disposed in spaced nested relation to one another so that in operation, the flexible convoluted portions are spaced from one another sufficiently that they are prevented from chafing one another. The flexible convoluted portions are uniform in thickness throughout their length. An independent means of clamping the diaphragm pack together is provided in the coupling design so that the diaphragm pack acts as a cohesive member. The thickness of the inner filler portion may be about 2.5 times greater than the thickness of the flexible convoluted portion. The inner clamping parts comprise first and second

annular engaging members approximately co-extensive with and overlying inner annular filler portions of the stacked plurality of diaphragm members that are held together by inner holding means providing a diaphragm pack as a unit when diaphragm members are supported in an operating position, the outer clamping parts comprise first and second annular outer engaging members that are approximately coextensive with overlaying annular filler portions of the plurality of diaphragm members. Outer holding means are provided for supporting the outer clamping parts engaged with the outer filler portions, thus holding this pack together in a unit when the diaphragm members are supported in an operating position. The inner filler portions and the outer filler portions may be approximately twice as thick as the flexible convoluted portion in cross section.

The specification concludes with claims particularly pointing out and distinctly claiming the subject matter of this invention. The organization and manner and process of making and using this invention, together with further objects and advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings. The same number is used to designated identical parts shown in more than one drawing.

It is an object of the invention to provide an improved flexible coupling capable of higher misalignments, smaller physical dimensions and lower weight at higher rotational speeds.

Another object of the invention is to provide an improved diaphragm pack for use in a flexible coupling.

Another object of the invention is to provide a flexible coupling that is simple in construction, economical to manufacture and simple and efficient to use.

Another object of the invention is to provide a flexible coupling with stability during a single diaphragm failure at high misalignments or restricted diameters.

With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawing and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions and minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIGURE 1 is a longitudinal cross sectional view of a flexible diaphragm coupling according to the invention.

FIGURE 2 is an end view of a flexible diaphragm.

FIGURE 3 is a cross sectional view taken on line 3-3 of Figure 2.

FIGURE 4 is a view similar to Figure 3 of a flexible diaphragm pack.

FIGURE 5 is an enlarged view of a portion of an outer periphery of one of the flexible diaphragms.

FIGURE 6 is an enlarged view of a portion of an inner periphery of one of the flexible diaphragms.

FIGURE 7 is an enlarged view of an outer periphery of one of the diaphragm packs.

FIGURE 8 is an enlarged view of the inner periphery of the flexible diaphragm packs.

FIGURE 9 is a longitudinal cross sectional view of a flexible disc coupling with one diaphragm pack according to the invention.

FIGURE 10 is a view of the diaphragm pack cross section constructed from separated diaphragms at high misalignments that illustrates the potential for contact and chafing between flexing members and possible failures.

FIGURE 11 is a view of a diaphragm pack cross section constructed from integral filler diaphragms where at high misalignments contact is eliminated between critical flexing surfaces.

FIGURE 12 is a view which shows the offset stress due to filler section thickness which is related to the distance from the diaphragm pack center line.

FIGURE 13 is a longitudinal cross section view of a flexible diaphragm coupling with diaphragm packs connected in series to facilitate even larger misalignments as outlined in this invention.

PREFERRED EMBODIMENT OF THE INVENTION Now with more particular reference to the drawings , Figure 1 shows a longitudinal cross sectional view of flexible coupling 10 according to the invention for providing a flexible connection between first rotatable member 11 and second rotatable member 12 through first drive flange 13 and second drive flange 14. First drive flange 13 and second drive flange 14 may be attached to diaphragm pack 20 to provide a flexible coupling between first rotatable member 11 and second rotatable member 12.

To increase the distance between the first drive flange

13 and the second drive flange 14 the shaft 15 may be provided in a suitable length and be attached at first end 16 which is attached to diaphragm pack 20 and may be attached at second end 17 which is connected to another diaphragm pack 20. Diaphragm pack 20 at first end 16 may be attached to first drive flange 13 and another diaphragm pack 20 at second end 17 may be attached to second drive flange

14 to provide a complete flexible coupling 10 capable of transmitting all misalignments between first rotatable member 11 and second rotatable member 12. Diaphragm packs 20 may also be placed in series by separating the outside diameter of the diaphragm packs with spacers 39 and on each end of the series, the diaphragm pack on the first end may be attached to first drive flange 13 and the diaphragm pack on the second end may be attached to second drive flange 14 to provide even greater flexibility.

Each diaphragm pack 20 is made up of a plurality of diaphragm members 22, inner annular clamping parts 44 and outer annular clamping parts 46. Each diaphragm member 22 has annular flexible convoluted portion 24, annular inner filler portion 26, annular outer filler portion 28, annular inner transition portion 30, annular outer transition portion 32. Annular inner filler portion 26 and annular outer filler portion 28 are substantially thicker than annular flexible convoluted portion 24. Annular inner transition portion 30 provides a smooth transition from the thicker annular inner filler portion 26 to the thinner annular flexible convoluted portion 24. Annular outer transition portion 32 provides a smooth transition from the thicker outer filler portion 28 to the thinner annular flexible convoluted portion 24. Each annular inner filler portion 26 comprises two flat parallel sides 34 which are adapted to engage the flat parallel sides of the adjoining filler portions 26 when the diaphragm members are stacked together in an operating position. The inner flat surfaces of the stack of one or more diaphragm members 22 are engaged by annular inner clamping part 44, on each side of the diaphragm pack 20. Each annular inner filler portion 26 has an inner periphery defining hole 38. Each annular outer filler portion 28 comprises two flat parallel sides 36 which are adapted to engage the flat parallel sides of the adjoining filler portions 28 when the diaphragm members are stacked together. The outer flat surfaces of the stack of one or more diaphragm members 22 are engaged by annular inner clamping part 46.

Each diaphragm member 22 is constructed so that they may be stacked with the flat sides of outer filler portions 28 resting against one another and the flat sides of inner clamping portions 26 resting against one another so that flexible convoluted portions 24 of diaphragm member 22 will be disposed in spaced nested relation to one another, and

thus, not touching one another when flexible coupling 10 is operated so that flexible convoluted portions 24 and transitions 30 and 32 are prevented from chafing one another.

In a preferred embodiment, flexible convoluted portion 24 is uniform in thickness throughout its area and further flexible convoluted portions of diaphragm members 22 are sinuous in cross section.

Outer transition portion 32 lies between outer filler portion 28 and flexible convoluted portion 24 of diaphragm member 22.

The thickness of annular inner filler portion 26 and outer filler portion 28 may be about 2 to 2.5 times greater than the thickness of flexible convoluted portion 24. Inner annular clamping parts 44 are generally coextensive with and overlay the annular inner filler portions 26 of the stack of diaphragm members 22. Inner clamping parts 44 consist of first inner engaging member 43 and second inner engaging member 45. Inner holding means 41 are provided for supporting the annular inner filler portions 26 engagement with the inner engaging members when the diaphragm members 22 are supported in operating position. Annular outer clamping parts 46 are approximately coextensive with and overlying the annular outer filler portions 28 of the stack of diaphragm members 22. Outer clamping parts 46 consist of first outer engaging member 47 and second outer engaging member 48. Outer holding means 42 is provided for supporting outer engaging members in engagement with outer filler portions 28 so that diaphragm members 22 are supported in operating position. Annular inner filler portions 26 and outer filler portions 28 are of a uniform thickness and may be approximately twice as thick as flexible convoluted portion 24 of diaphragm member 22. The inner transition portion may comprise an arcuate continuation which extends tangentially from each side of

the flexible convoluted portion 24 and is defined by arcuate surfaces which extend outwardly and terminate at flat parallel sides 34 of annular inner filler portion 26. The arcuate continuation may consist of a surface defined by a radius tangent to each side of the flexible convoluted portion 24, the radius surfaces extend outwardly and terminate at flat parallel sides 34 of annular inner filler portion 26 on each side. Similarly.annular outer transition portion 32 may comprise an arcuate continuation extending tangentially from the side of flexible convoluted portion 24, the arcuate continuation being defined by surfaces which extend outwardly and terminate at flat parallel sides 36 of the outer filler portion on each side. The arcuate continuation may consist of a surface defined by a radius tangent to each side of flexible convoluted portion 24, the radius surfaces extend outwardly and terminate at flat parallel sides 36 of annular outer clamping portion 28 on each side. Flexible convoluted portion 24 of diaphragm members 22 are sinuous in cross section. Each sinuous flexible convoluted portion 24 of each diaphragm member 22 may be comprised of first arcuate part 50 having first end 51, second 52 and first radius of curvature 53. Second arcuate part 54 of flexible convoluted portion 24 may have first end 55, second end 56 and second radius of curvature 57. First end 51 of first arcuate part 50 being integrally attached to first end 55 of second arcuate part 54. Second end 52 of first arcuate part 50 being integrally attached to annular inner transition portion 30, second end 56 of second arcuate part 54 being integrally attached to annular outer transition portion 32. First radius of curvature and second radius of curvature may be selected to maximize operation of diaphragms and each may be larger than, smaller than, or same as the other which would make the first and second arcuate parts 50 and 54 same as, longer than or shorter than

the other. Annular outer transition portion 32 may comprise arcuate continuation extending tangentially from each side of the flexible convoluted portion of the arcuate continuation being defined by surfaces which extend outwardly and terminate at flat parallel sides 36 of the annular outer clamping portion on each side. Arcuate continuations may comprise radius surface tangent to each side of flexible convoluted portion 24, radius surfaces terminating at annular outer filler portion 28 on each side.

Coupling shaft 15 may be connected between first diaphragm pack 18 and second diaphragm pack 19 to provide a tandem coupling. The first end 16 of coupling shaft 15 may be connected to first diaphragm pack 18, second end 17 of coupling shaft 15 may be connected to second diaphragm pack 19 and each diaphragm pack 20 may be made up of a plurality of thin annular diaphragm members 22, annular inner clamping parts 44 and annular outer clamping parts 46.

A plurality of diaphragm packs 20 may be employed by placing a spacer 39 between each adjacent pair of diaphragm packs, the coupling spacer 39 being suitably attached between each of the diaphragm packs. At the first end of the flexible diaphragm coupling series,- first drive flange 13 connects the first rotatable member to the inner diameter of the first end diaphragm pack 20, and at the second end of a flexible diaphragm coupling train, second drive flange 14 connects the second rotatable member to the inner diameter of the second end diaphragm pack 20.

The foregoing speci ication sets forth the invention in its preferred, practical forms but the structure shown is capable of modification within a range of equivalents without departing from the invention which is to be understood is broadly novel as is commensurate with the appended claims.