Device for coupling two rotary machines

Claim 2

In a frangible device for coupling two rotary machines between which power is transmitted, a first shaft connected to one said machine, having a bore in one end thereof, and a frangible groove, a second shaft connected to the other said machine and having a bore in one end thereof, means defining a dog clutch operative between the first and second shafts in a first rotational sense, an intermediate shaft accommodated in the respective end bores of the first and second shafts, fast for rotation with said shafts, and having a frangible groove adapted to fracture at a lower torque value than that of the frangible groove of the first shaft and under conditions in which the sense of motion transmission is opposite to that intended to fracture the frangible groove of the first shaft, said intermediate shaft having two parts after fracture, means operative in the event of fracture of the frangible groove of the intermediate shaft to space the first and second shafts apart and the fractured parts of the intermediate shaft whereby to avoid mutual contact of these parts, said means serving to prevent axial motion of the second shaft under these conditions, the improvement comprising the provision on the dogs of the clutch of inclined opposed faces on the two halves thereof and spaced such that alternating deflections exerted on the first and second shafts causes uncoupling of the two halves of the clutch and thus of the shafts by the inclined faces riding up the one on the other, means operative in the event of fracture of the frangible groove of the intermediate shaft to retain one part of the fractured intermediate shaft rigid with the second shaft, said means operative in the event of fracture of the frangible groove of the intermediate shaft to space the first and second shafts apart, including a first part of the second shaft, a second part of the second shaft having a bore with a groove in the bore, spline means coupling the first and second parts, balls disposed adjacent the end of an first part of the second shaft opposite said dog clutch means and in transverse apertures thereof, a compression spring, a transverse bush housing the compression spring so that opposed ends thereof bias the balls radially outwardly, the arrangement being such that in the event of axial displacement of the first part of the second shaft relative to the second part thereof, the balls are displaced outwardly under the action of the spring and centrifugal force into the groove of the bore of the second shaft and are maintained therein so that contact between the dogs of the clutch and between the fractured ends of the intermediate shaft are prevented.

Claim 3

A device according to claim 1, wherein the ratio of torque transmission in the opposed senses of rotation are in a ratio lying between 1 to 5 and 1 to 500.

Claim 4

In a frangible device for coupling two rotary machines between which power is transmitted, a first shaft connected to one said machine, having a recess in one end thereof, and a section incorporating a frangible groove, a second shaft connected to the other said machine and having a recess in one end thereof contiguous with the end recess of the first shaft, means defining a dog clutch operative between the first and second shafts in a first rotational sense, an intermediate shaft accommodated in the respective end recesses of the first and second shafts, fast for rotation with said shafts, and having a section with a frangible groove adapted to fracture at a lower torque value than that of the section with frangible groove of the first shaft and under conditions in which the sense of motion transmission is opposite to that intended to fracture the frangible groove of the first shaft, said intermediate shaft having two parts after fracture, means operative in the event of fracture of the section with frangible groove of the intermediate shaft to space the first and second shafts apart axially and also the fractured parts of the intermediate shaft whereby to avoid mutual contact of these shafts and parts, said means serving to prevent axial motion of the second shaft under these conditions, the improvement comprising the provision on the dogs of the clutch of inclined opposed faces on the two halves of the clutch and spaced such that alternating deflections exerted on the first and second shafts causes uncoupling of the two halves of the clutch and thus of the shafts by the opposed inclined faces riding up the one on the other, means operative in the event of fracture of the section with frangible groove of the intermediate shaft to retain one said part of the fractured intermediate shaft rigid with the second shaft and within said recess, said means operative in the event of fracture of the section with frangible groove of the intermediate shaft to space the first and second shafts apart, including a first, hollow, cylindrical, part of the second shaft having transverse apertures adjacent one end, a second, hollow, cylindrical, part of the second shaft having a bore with a groove in the bore, spline means coupling the first and second parts, members disposed adjacent the end of the first part of the second shaft in said transverse apertures thereof, resilient means, a transverse hollow member housing the resilient means so that opposed ends thereof bias the members radially outwardly, the arrangement being such that in the event of axial displacement of the first part of the second shaft relative to the second part thereof, the members are displaced outwardly under the action of the resilient means and centrifugal force into the groove of the bore of the second shaft and are maintained therein so that contacts between the dogs of the clutch and between the fractured ends of the intermediate shaft are prevented.

Claim 5

In a frangible device for coupling two rotary machines between which power is transmitted, a first shaft connected to one said machine, having a recess in one end thereof, and a section incorporating a frangible groove, a second shaft connected to the other said machine and having a recess in one end thereof contiguous with the end recess of the first shaft, means defining a dog clutch operative between the first and second shafts in a first rotational sense, an intermediate shaft accommodated in the respective end recesses of the first and second shafts, fast for rotation with said shafts, and having a section with a frangible groove adapted to fracture at a lower torque value than that of the section with frangible groove of the first shaft and under conditions in which the sense of motion transmission is opposite to that intended to fracture the frangible groove of the first shaft, said intermediate shaft having two parts after fracture, means operative in the event of fracture of the section with frangible groove of the intermediate shaft to space the first and second shafts apart axially and also the fractured parts of the intermediate shaft whereby to avoid mutual contact of these shafts and parts, said means serving to prevent axial motion of the second shaft under these conditions, the improvement comprising the provision on the dogs of the clutch of inclined opposed faces on the two halves of the clutch and spaced such that alternating deflections exerted on the first and second shafts causes uncoupling of the two halves of the clutch and thus of the shafts by the opposed inclined faces riding up the one on the other, means operative in the event of fracture of the section with frangible groove of the intermediate shaft to retain one said part of the fractured intermediate shaft rigid with the second shaft and within said recess, said means operative in the event of fracture of the section with frangible groove of the intermediate shaft to space the first and second shafts apart, including a first, hollow, cylindrical, part of the second shaft having transverse apertures adjacent one end, a second, hollow, cylindrical, part of the second shaft having a bore with a groove in the bore, spline means coupling the first and second parts, members disposed adjacent the end of the first part of the second shaft in said transverse apertures thereof, resilient means, a transverse hollow member housing the resilient means so that opposed ends thereof bias the members radially outwardly, the arrangement being such that in the event of axial displacement of the first part of the second shaft relative to the second part thereof, the members are displaced outwardly under the action of the resilient means and centrifugal force into the groove of the bore of the second shaft and are maintained therein so that contacts between the dogs of the clutch and between the fractured ends of the intermediate shaft are prevented.