| Title of Invention | MUFF COUPLING ASSEMBLY |
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| Abstract | A muff coupling assembly for coupling ends of shafts to each other is disclosed. |
| Full Text | FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE Specification (See section 10 and rule 13) MUFF COUPLING ASSEMBLY KIRLOSKAR BROTHERS LTD., an Indian Company of Udyog Bhavan, Tilak Road, Pune 411 002, Maharashtra, India THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. FIELD OF INVENTION This invention relates to shaft couplings. In particular this invention relates to Muff couplings used for transmission of power between shafts. BACKGROUND A coupling is used to connect two in-line shafts to allow one shaft (driver) to drive the second shaft (driven) at the same speed. A coupling can be rigid or, it can be flexible allowing relative radial, axial or angular misalignment of the two shafts. A rigid or flexible coupling is not designed for an engage-disengage type of operation. The coupling is disconnected only for maintenance or dismantling the drive unit. Various types of couplings are used to suit different applications and the most commonly used couplings are: Rigid Coupling Flanges are locked onto each of the shafts with keys and key-ways. One of the flanges is provided with recess on the mating face and the other with matching spigot. Flanges are bolted together to form rigid coupling. This coupling allows no tolerance for misalignment of the shafts namely radial, angular or axial misalignments. Muff Coupling A long cylindrical coupling is bored and keyed to fit over both shafts. The coupling is split axially and clamped over both shafts with recessed bolts. 2 Muff couplings are rigid couplings used for transmitting high torques at high speeds. Pin and bush type couplings These are similar to rigid couplings but flanges are not provided with recess and spigot for alignment purpose. The bolts are replaced by pins with rubber bushes. This design allows certain flexibility and accommodates marginal misalignment of the shafts. Flexible Rubber disc couplings These are similar to rigid couplings except that a thick rubber disc bonded between steel plates is located between the flanges. The plates are bolted to the adjacent coupling flanges. This design also allows certain flexibility and accommodates misalignment of the shafts. Spider type Coupling In this design both halves of the couplings have three shaped lugs. When the coupling halves are fitted together the lugs on one half fit inside the spaces between the lugs on the other side. A Rubber insert with six legs fits within the spaces between the lugs. The driver shaft coupling half transmits the torque through the rubber spider spacer to the driven shaft. This coupling is used only for low power drives. Chain Coupling Flanges are replaced by sprockets on each shaft. The coupling is by a duplex chain wrapped over both adjacent coupling. 3 Gear Coupling Both coupling halves have a raised rim machined as an external gear. The sleeve which couples the two shafts comprises two halves bolted together, each half having a machined internal gear. This coupling requires lubrication. The coupling is capable of high speeds and high power capacity. Metastream Coupling Coupling halves are connected using stainless steel diaphragms. These couplings have high speed, high torque capability with good dynamic balance. Single coupling will accommodate angular and radial misalignment and fitted in pairs also allows lateral misalignment. Fluid Coupling Shafts are connected to coupling halves having vanes within a housing containing viscous fluid. The rotation is transmitted from one side to the other via the viscous fluid. These couplings provide a soft start and are used in application having high static loads on the driven shaft. The selection of coupling to be used for a specific application would depend on power to be transmitted, shaft speed, space availability, level of vibration permissible and location of the coupling with reference to the bearings. Muff couplings are used in high power high speed transmission drives where there is limited availability of space around the shaft and ease of removal of system component is an essential consideration. Muff couplings have been used in applications where accurate alignment of the shaft is possible as 4 these couplings do not have any provision to accommodate radial, angular or axial misalignment of the shafts. In applications like vertical turbine pumps and wet pit vertical sump pumps where the prime mover is at a considerable distance from the impeller in the pump unit, a series of shafts, connected by rigid couplings are used to transmit the power. These shafts are enclosed in protection pipes and column pipes. The protection pipes protect the shafting from corrosive and erosive attack of liquid flowing in the column pipes. As the space available around the couplings is limited these couplings should have bare minimum outside diameter. Also components like gland packing, mechanical seal and bearings have to be replaced regularly to maintain the unit in good working condition. These couplings therefore should be easy to assemble and dismantle while maintaining the alignment accuracies. Also in these applications the transmission of power has to be through positive mechanical means like keys locking the shaft and the hub to prevent seizure of coupling with the shafts. In applications where limited space is available to mount tools required for verification of shaft alignment, accurate alignment of the shafts to be coupled is difficult and time consuming. 5 Prior Art Several attempts have been made in this field to provide muff couplings which are easy to assemble and at the same time fulfill the other essential functional requirements. US Patent 4240762 discloses a self-aligning rigid coupling assembly consisting of a pair of cylindrical rigid hubs, split rings, split spacer and shims to provide vertical position adjustment of pump shaft relative to driver shaft. Use of two separate cylindrical hubs and split spacer increases the number of components to be fastened and placement of split shims in the mating face having bolting arrangement is difficult. US Patent 5333963 discloses a shaft coupler with a cylindrical solid muff for fitment on one of the shafts and a split muff for fitment on the other shaft. Interconnection of the couplings is through fasteners provided on the flange face. Assembly and dismantling of the coupling will be time consuming as number of fasteners has to be tightened or loosened. Objects of the invention One of the objects of the present invention is to provide a muff coupling which self aligns the shaft for assembly Another object of the present invention is to provide a muff coupling which is suitable for in situ assembly 6 Yet another object of the present invention is to provide a muff coupling designed for repeated interchangeable assembly while maintaining the accuracy of alignment. Yet another object of the present invention is to provide a muff coupling which can be dismantled easily. Yet another object of the present invention is to provide a muff coupling which is economical to use. Summary of the invention According to the present invention there is provided a muff coupling assembly for coupling ends of shafts to each other; said assembly defined by, i. a stepped profile formed at the end of each of the shafts; ii. a split ring having at least two elements which in their operatively assembled configuration contouringly enclose the profiled ends of the two shafts in a non abutting engagement with respect to each other, characterised in that, the split ring elements define reentrant flanges at their ends which collectively form a nestling enclosure for receiving and permitting nestling of the stepped profiled ends in a spaced apart configuration there within; in said operatively assembled configuration the outer surfaces of the elements of the split ring are in alignment with the outer surface of the shaft; 7 iii. a muffin the form of a sleeve defining an inner passage adapted to receive and contour the coupled ends of the shaft nestled in said split ring elements; and iv. a set of complementary keys adapted to removably lock the shafts with reference to the muff. Typically each of the shafts has a key slot adapted to receive a complementary key. Typically the stepped profile formed on the shafts has chamfered ends. Typically the split ring has more than two elements. Typically the split ring elements have longitudinal v grooves formed on the outer surface along the mating faces of the elements. Typically the outer periphery of the muff is a profile selected from profiles consisting of circle, ellipse, square, triangle, rectangle and polygon. Typically the inner passage of the muff has a key way slot adapted to receive said complementary keys. Typically the muff has at least two radial threaded holes provided with fasteners, adapted to lock the key in the muff and the shaft. Typically the shaft axes are collinear and are operatively vertical in an assembled operative configuration. Typically the shaft axes are collinear and are operatively horizontal in an assembled operative configuration. Typically the shaft axes are collinear and are operatively inclined in an assembled operative configuration. 8 Brief description of drawings.: All the aspects and advantages of the invention will become apparent with the description of the preferred, non-limiting embodiment, when read together with the accompanying drawings in which: Figure 1 is the assembled view of the muff coupling; Figure 2 is the elevation of the shafts of the muff coupling of Figure 1; Figure 3 is the sectional elevation of the split ring of the muff coupling of Figure 1; Figure 4 is the plan of the split ring of the muff coupling of Figure 1; Figure 5 is the sectional elevation of coupling pusher used for assembly of muff coupling of Figure 1; Figure 6 is the plan view of coupling pusher used for assembly of muff coupling of Figure 1; Figure 7 Shows the perspective view of wedge tool used for disassembly of split ring from the muff coupling of Figure 1; Figure 8 Shows the exploded view of the muff coupling of Figure 1. Detailed description of the invention: Referring to the accompanying drawings, the muff coupling according to this invention is indicated generally by the reference numeral 10. 9 Referring to Figure 1, the muff coupling consists of shafts 12 and 20 having ends formed to stepped profiles 14 and 22. The shafts also have machined key way slots 16 and 24 (refer Figure 2).Keys 18 and 26 are used to lock the shafts to the muff sleeve 40. Split ring consisting of at least two elements 30 and 32 have machined inner contours 34 (refer Figure 3) complementing the stepped profile 14 and 22 machined on the shaft ends. In its assembled configuration the split ring elements 30 and 32 enclose the step profiles 14 and 22 and hold the shafts in alignment with each other and with predetermined clearances on the end faces. Also the outer surface of the split ring elements align with the out side diameter of the shafts 12 and 20. The muff 40 in the form of a sleeve has inner dimension complementing that of the shafts. In its final assembled configuration the muff contours and encloses the shafts (12, 14) and split rings (30, 32). Referring to figure 3 the split ring 30 and 32 have machined inner contours 34 with chamfers 38 provided to protect the step profile 14 and 22 machined on the shaft ends and position the shafts with reference to each other with adequate and predetermined clearances on the end faces. The split rings 30 and 32 have V grooves 36 on their mating faces for easy disassembly of the coupling. For quick assembly of the muff coupling a coupling pusher (refer Figure 5 and 6) indicated generally by the reference numeral 50 is used. The coupling pusher consists of two halves 52 and 54 bolted together with fasteners 58. The coupling pusher is tightened on one of the shafts and threaded bolts 56 are tightened in a sequential manner to push the muff along the shaft to its final position. 10 Figure 8 shows a split ring wedge tool used to quickly dislodge the split rings 30 and 32 during dismantling of the coupling. The tool has an included wedge angle sufficient to split the rings with out damaging the outer surfaces. Figure 9 shows the solid exploded view of the muff coupling. While considerable emphasis has been placed herein on the particular features of a, muff coupling assembly for coupling ends of shafts to each other, the improvisation with regards to it, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiment without departing from the principles of the invention. These and other modifications in the nature of the invention or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. 11 We Claim: 1. A muff coupling assembly for coupling ends of shafts to each other; said assembly defined by, i. a stepped profile formed at the end of each of the shafts; ii. a split ring having at least two elements which, in their operatively assembled configuration, contouringly enclose the profiled ends of the two shafts in a non abutting engagement with respect to each other, characterised in that, the split ring elements define reentrant flanges at their ends which collectively form a nestling enclosure for receiving and permitting nestling of the stepped profiled ends in a spaced apart configuration therewithin and in said operatively assembled configuration the outer surfaces of the elements of the split ring are in alignment with the outer surface of the shaft; iii. a muffin the form of a sleeve defining an inner passage adapted to receive and contour the coupled ends of the shaft nestled in said split ring elements; and . iv. a set of complementary keys adapted to removably lock the shafts with reference to the muff. 2. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein each of the shafts has at least one key slot adapted to receive at least one complementary key. 3. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein said stepped profile formed on the shafts has chamfered ends. 12 4. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein the split ring has more than two elements. 5. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein the split ring elements have longitudinal 'V grooves machined on the outer surface along the mating faces of the elements. 6. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein the outer periphery of the muff has a profile selected from profiles consisting of a circle, an ellipse, a square, a triangle, a rectangle and a polygon. 7. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein said inner passage of the muff has at least one key way slot adapted to receive said complementary keys. 8. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein the muff has at least two radial threaded holes provided with fasteners, adapted to lock the keys in the muff and the shaft. 9. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein the shaft axes are collinear and are operatively vertical in an assembled operative configuration. 13 10. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein the shaft axes are collinear and are operatively horizontal in an assembled operative configuration. 11. A muff coupling assembly for coupling ends of shafts to each other as claimed in claim 1, wherein the shaft axes are collinear and are operatively inclined in an assembled operative configuration. 12. A muff coupling assembly for coupling ends of shafts to each other as described herein with reference to the accompanying drawings. 14 ABSTRACT A muff coupling assembly for coupling ends of shafts to each other is disclosed. |
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| Patent Number | 270567 | |||||||||
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| Indian Patent Application Number | 1236/MUM/2007 | |||||||||
| PG Journal Number | 01/2016 | |||||||||
| Publication Date | 01-Jan-2016 | |||||||||
| Grant Date | 31-Dec-2015 | |||||||||
| Date of Filing | 28-Jun-2007 | |||||||||
| Name of Patentee | KIRLOSKAR BROTHERS LTD. | |||||||||
| Applicant Address | UDYOG BHAVAN, TILAK ROAD, PUNE. | |||||||||
Inventors:
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| PCT International Classification Number | E04G7/20, F16B7/04, E04G7/00 | |||||||||
| PCT International Application Number | N/A | |||||||||
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PCT Conventions:
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