Patent Application
20060009297
Not Applicable
Not Applicable
This invention relates to flexible shaft couplings, and more particularly, to composite flexible couplings for transmitting torque between two shafts approximately aligned on a shaft axis, i.e., to flexible couplings joining a pair of axially spaced shafts. Flexible diaphragm couplings comprising a pair of shoes joined by a generally U-shaped flexible center element, such as disclosed in U.S. Pat. Nos. 4,634,400; 6,080,065; 6,117,015; 6,196,926; and 6,257,985, all issued to the assignee of the present application, can accommodate axial misalignments (i.e. the spacing between the shafts is not optimum per coupling design) and angular misalignments (i.e. the shaft axes intersect at a point) without large stresses by using a bellows actions. U.S. Pat. Nos. 4,634,400; 6,080,065; 6,117,015; 6,196,926; and 6,257,985 are all fully incorporated herein by reference.
These known couplings, however, have difficulty accommodating lateral misalignment (i.e. the shaft axes do not intersect and are not coaxial). One known method for coupling laterally misaligned shafts is to provide a flexible diaphragm coupling having an oversized flexible center element that can accommodate the bellows action in orthogonal directions. Unfortunately, the oversized flexible center element increases the coupling mass which increases the loads and forces on the hub attachment assembly. Moreover, the large flexible element can decrease the torsional stiffness of the coupling and increase wind up deformation. Accordingly, a need exists for an improved coupling which can accommodate axial, lateral, and angular shaft misalignments.
The present invention provides a flexible coupling for transmitting torque between two shafts approximately aligned on a shaft axis, and a method of making the novel coupling. The coupling can accommodate axial, lateral, and angular shaft misalignments without the problems associated with prior art couplings. One embodiment of a flexible coupling incorporating the present invention includes an arcuate flexible center element having two axially spaced radially extending leg portions joined by an axially extending bridging portion. The axially extending bridging portion has at least two opposing re-entrant folds defining a T-shaped cross-section in a radial plane extending from and along the shaft axis.
A general objective of the present invention is to provide a flexible coupling that can accommodate axial, lateral, and angular shaft misalignments without the problems associated with prior art diaphragm couplings. This objective is accomplished by providing a coupling having a center element including a bridging portion with at least two opposing re-entrant folds defining a T-shaped cross-section in a radial plane extending from and along the shaft axis.
The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention.
Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of the construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
A composite flexible diaphragm coupling 11 for transmitting torque between first and second axially spaced and oppositely extending shafts 13 and 15 which are approximately aligned on a shaft axis 17 is shown in
Because the first and second composite members 21 and 23 are generally identically constructed, only the first composite member 21 will be described in detail. More specifically, the first and second shoes 31 and 33 are also of generally identical construction and each arcuately extends for an arcuate distance which can be almost 180 degrees. In addition, the first and second shoes 31 and 33 extend axially in opposite directions to each other. More particularly, the first and second shoes 31 and 33 each include an inner part 51 which is bonded to the central element 41, and an outer part 53 which extends from the inner part 51 and which is adapted, in any suitable way, to be connected to an associated one of the oppositely extending shafts 13 and 15. In the particularly illustrated construction, the outer parts 53 each include one or more apertures 55 which permit the shoes 31 and 33 to be fixed by bolts 30 to generally cylindrical hubs 32. The hubs 32 include central bores 34 housing the shafts 13 and 15.
The shoes 31 and 33 can take any number of suitable configurations and, in the disclosed construction, the inner and outer parts 51 and 53 are preferably of generally semi-cylindrical configuration. In addition, the shoes 31 and 33 can be fabricated of any suitable metallic or plastic material and, in the disclosed construction, are preferably fabricated of suitable plastic material.
The center element 41 is formed from a composite sheet material, and includes first and second leg portions 61 and 63 which are generally identically constructed and which are axially spaced from each other and joined by a bridging portion 65. The sheet material is preferably a glass fiber fabric impregnated with a vinyl ester resin, however any flexible material, such as a urethane material, can be used without departing from the scope of the invention. The leg portions 61, 63 and bridging portion 65 extend arcuately for an arcuate distance which is approximately 180 degrees.
Referring to
Advantageously, the bridging portion 65 including at least one pair of centrally located, opposing, outward, re-entrant folds 67, 69 which defines the T-shaped cross-section accommodates axial, lateral, and angular misalignments without the accompanying increase of coupling mass, loads and forces on the shafts, and wind up deformation, associated with prior art U-shaped cross-section center elements. Moreover, the center element 41 including the bridging portion 65 having the T-shaped cross-section provides a coupling with a diameter that is smaller than a prior art coupling sized for the same torque loads and misalignments.
The leg portions 61 and 63 each include a radially inner part 71 bonded to the cylindrical portion of the associated one of the shoes 31 and 33. The inner parts 71, respectively, include oppositely facing, arcuately extending recesses 75 which receive, and are bonded to, the inner parts 51 of the associated shoes 31 and 33. Any suitable method for bonding the shoes 31 and 33 to the inner parts 71 can be employed.
In
Each arcuate members 121, 123 is preferably formed from a suitable material as a single piece. The material is preferably a glass fiber fabric impregnated with a vinyl ester resin, however, as in the above described embodiments, any flexible material, such as polyether urethane, can be used without departing from the scope of the invention. Because the first and second arcuate members 121 and 123 are generally identically constructed, only the first arcuate member 121 will be described in detail.
The arcuate member 121 including an arcuate flexible T-shaped center element 141 having integral shoes 131, 133. The T-shaped center element 141 includes first and second leg portions 161, 163 joined by a bridging portion 165. The bridging portion 165 includes a pair of centrally located, opposing, outward, re-entrant folds 167, 169. Each fold 167, 169 is joined to one of the leg portions 161, 163 by a radially extending base portion 177, 179 to define a generally T-shaped cross-section in a radial plane extending from and along the shaft axis 117, wherein the T-shape has a radially extending stem 181 with a top 183 substantially perpendicular to the stem 181. As in the first embodiment, although only one pair of opposing, outward, re-entrant folds is shown, more than one pair of opposing, outward, re-entrant folds can be provided without departing from the scope of the invention.
Advantageously, as in the first embodiment, the T-shaped cross-section accommodates axial, lateral, and angular misalignments without the accompanying increase of coupling mass, loads and forces on the shafts, and wind up deformation, associated with prior art U-shaped cross-section center elements. Moreover, the center element 141 including the bridging portion 165 having the T-shaped cross-section provides a coupling with a diameter that is smaller than a prior art coupling sized for the same torque loads and misalignments.
The first and second leg portions 161, 163 extend in axially opposite directions from the bridging portion 165. Outer parts 162, 164 of the first and second leg portions 161, 163 form the integral shoes 131, 133 formed of the same material as the center element 141. The shoes 131, 133 are generally identically constructed and axially spaced from each other. Preferably, the shoes 131, 133 have a material thickness greater than the thickness of the material forming the bridging portion 165 to increase the shear strength of each shoe 131, 133. The additional thickness can be formed by applying additional material forming the shoes 131, 133 over the outer parts 162, 164 of the first and second leg portions 161, 163, or a different material, such as metal, an elastomer, and the like, can be embedded in, bonded to, or mechanically fastened to, to the outer parts 162, 164 of the first and second leg portions 161, 163 forming the shoe 131, 133.
Apertures 155 formed through shoes 131 and 133 receive bolts 130 which fix the coupling 111 to the shafts 113, 115. The bolts 130 pass through the apertures 155 and threadably engage hubs 132 fixed to the shafts 113, 115 to fix the coupling 111 to the shafts 113, 115. Of course, other methods for fixing the coupling to the shafts can be used, such as pinning (i.e. using pins extending through the coupling into the shafts), bonding (i.e. adhesives and other chemical fasteners), mechanically interlocking the coupling with the shafts, and the like, without departing from the scope of the invention. Grommets can be fixed in the apertures 155 to strengthen the aperture peripheries.
Referring now to
Once the material forming the coupling is applied onto the mandrel 187, molds 193, 195 axially slipped onto the mandrel 187 from opposing sides of the T-shape form 189 encloses the material applied to the mandrel 187 and T-shaped form 189, and urges the material to conform to the shape of the mandrel 187 and T-shape form 189. Resin, such as a vinyl ester resin, is injected into the mold to impregnate the glass fiber material and any other impregnable material forming part of the coupling 111, as is known in the art. The resin impregnated material is then cured, and cut axially along a plane intersecting the coupling axis to form the two arcuate members 121, 123. Advantageously, the center element 141 wrapped around the T-shaped form 189 is flexible to allow the removal of the arcuate members 121, 123 from the mandrel 187 and T-shaped form 189. Of course, the above method can used to make the flexible center element 41 of the first embodiments shown in
While there has been shown and described what are at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims. Therefore, various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.
