CA1079100A - Torque limiting clutch - Google Patents
Torque limiting clutchInfo
- Publication number
- CA1079100A CA1079100A CA315,769A CA315769A CA1079100A CA 1079100 A CA1079100 A CA 1079100A CA 315769 A CA315769 A CA 315769A CA 1079100 A CA1079100 A CA 1079100A
- Authority
- CA
- Canada
- Prior art keywords
- clutch
- recesses
- balls
- spindle
- torque
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D7/00—Slip couplings, e.g. slipping on overload, for absorbing shock
- F16D7/04—Slip couplings, e.g. slipping on overload, for absorbing shock of the ratchet type
- F16D7/06—Slip couplings, e.g. slipping on overload, for absorbing shock of the ratchet type with intermediate balls or rollers
- F16D7/10—Slip couplings, e.g. slipping on overload, for absorbing shock of the ratchet type with intermediate balls or rollers moving radially between engagement and disengagement
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- One-Way And Automatic Clutches, And Combinations Of Different Clutches (AREA)
- Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
Abstract
TORQUE LIMITING CLUTCH
ABSTRACT OF THE DISCLOSURE
A torque limiting clutch having a driving member provided with a plurality of spaced apart radially extending recesses which are adapted to hold clutch balls. A driven member is disposed around the driving member and has an inner cam surface adapted to coact with the clutch balls and force the clutch balls radially inward into their respective recesses in response to torque transmitted from the balls to the driven member. In one embodiment the balls are biased radially outward into engagement with the cam surface by a spring biased ring having a wedge sur-face coacting with the clutch balls. In another embodiment the radially extending recesses have an inclined ramp along which the balls are forced against a flat sided ring.
ABSTRACT OF THE DISCLOSURE
A torque limiting clutch having a driving member provided with a plurality of spaced apart radially extending recesses which are adapted to hold clutch balls. A driven member is disposed around the driving member and has an inner cam surface adapted to coact with the clutch balls and force the clutch balls radially inward into their respective recesses in response to torque transmitted from the balls to the driven member. In one embodiment the balls are biased radially outward into engagement with the cam surface by a spring biased ring having a wedge sur-face coacting with the clutch balls. In another embodiment the radially extending recesses have an inclined ramp along which the balls are forced against a flat sided ring.
Description
BACKGROUND OF THE INVENTION
This invention pertains to improvements in torc~le limiting or overload release clutches of the type which are used in power tools for tightening threaded fasteners and the like. The develop-ment of torque limiting clutches for power tools has resulted in numerous inventions which are generally characterized by a driving clutch member having an external polygonal cam surface and a plurality of drive balls or rollers retained in a driven member in yieldable engagement with the cam surface. At a predetermined torque the balls or rollers ride up and over the peaks of the cam surfaces to allow relative rotation between the driving and driven members to limit the torque output of the tool. The im-pulses caused by the balls riding over the cam peaks are normallysensed by the tool operator and serve as an indication that the limit .orque output of the tool has been achieved. Examples of the types of torque limiting clutches referred to above are dis-closed in U.S. Patents 2,957,323 to C.A. Elliott et al; 2,978,082 ~;~
1079~00 to B.R. Better, and 3,005,325 to R.E. Eckman. A variation of the aforementioned clutch design is disclosed in U.S. Paten~
No. 3,937,036 to W.D. Sauerwein.
In the first three above mentioned patents the driving clutch member is characterized by an external hexagonal cam configuration.
One disadvantage of this type of cam is that the peaks formed by the intersection of the sides of the hexagon are subject to con-centrated stresses which can result in rapid wear and early failure of the mechanism. Other torque limiting clutch designs character-ized b~ members which have sharp edged recesses from which thedrive balls are displaced also have the disadvantage of being subject to rapid wear and causing poor torque control because of the impacts or torque pulses which are delivered to the driven member as the balls or rollers move in and out of the recesses.
SUMMARY OF THE INVENTION
The present invention provides for a torque limiting clutch for a power tool or the like which is operable to allow the tool motor and drive train ahead of the clutch to continue operating when a limit torque has been exceeded without causing excessive wear on the clutch members and while maintaining superior control of the predetermined limit torque over an extensive torque range.
In the torque limiting clutch of the present invention im-proved cperating life of the clutch is realized ~y a design wherein one of the clutch members includes cam surfaces for engagement with a plurality of drive balls which cam surfaces are not subject to concentrated stresses and the rapid wear associated therewith.
In the present invention the driving or driven clutch member may be characterized by a bore having an inner surface geometry or profile which is operable to permit movement of the balls over the cam surfaces at an accurately controlled predetermined torque and with an unexpected improvement in the operating life of the cam.
~ -2-107~100 In accordance with one broad aspect, the invention relates to a torque limiting clutch for use in a power operated tool for tightening threaded fasteners and the like, said clutch including: a rotatable driven member; a driving member rotatable with respect to said driven member at a predetermined torque transmitted by said clutch to a driven spindle; one of said members being characterized by a continuously curved internal cam surface including a plurality of spaced apart recesses extending radially outwardly with respect to the axis of rotation of said spindle and in a plane perpendicular to the axis of rotation of said one member said recesses are formed by substantially concave curved surface portions which are interconnected by substantially convex curved surface portions disposed radially inwardly of said concave curved surface portions with respect to the axis of rotation of said one member; the other of said members including a radially, outwardly extending rim having at least one transverse face and a plurality of radially extending grooves in said rim opening to said face and being spaced apart so as to be respectively alignable with said recesses; movable elements disposed in said grooves and operable to be biased radially outwardly into said recesses for coupling said driving and driven members for rotation together to transmit torque to said spindle; a third member having a surface disposed adjacent said transverse face on said other member and engaged with said movable elements; and, resilient means engaged with said third member for causing said third member to yieldably urge said movable elements into said recesses in said one member and whereby at a predetermined limit torque said elements are forced radially inwardly in said grooves by said cam surface to allow said driving member to rotate with respect to said driven member.
iO79100 One embodiment of the present invention also provides a torque limiting clutch which may be adapted to operate over a large range of limiting torques by interchanging an inexpensive member of the clutch assembly.
The present invention further provides for a torque limiting clutch which has a relatively few working parts, is inexpensive, and is easy to manufacture.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a lcngi~udinal sectional view of one embodiment of a torque limiting clutch of the present invention;
Fig. 2 is a section view taken along the line 2-2 of Fig. l;
Fig. 3 is a longitudinal sectional view of an alternate em-bodiment of the torque limiting clutch;
Fig. 4 is a section view taken along the line 4-4 of Fig. 3;
and, Fig. 5 is a perspective view of an alternate torque control ring for use with the clutch embodiment shown in Figs. 1 and 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Fig. 1 a torque limiting clutch in accordance with the present invention is generally designated by the numeral 10 and is shown disposed in a housing 12 comprising a portion of a power tool for tightening threaded fasteners and the like. The housing 12 is adapted to be removably connected to a tool motor unit, not shown, in a conventional manner. The housing 12 includes a bore 14 comprising bearing means for supporting a rotatable spindle 16. The spindle 16 includes a removable sleeve 18 having a polygonal bore 20 engaged with one end of the spindle and adapted to receive a tool bit or the like, not shown. The opposite end of the spindle 16 includes a cylindrical bearing portion 22 on which is mounted a driving member 24 of the torque limiting clutch 10.
The member 24 is retained on the bearing portion 22 by a retaining iO79100 ring 26 and is operable to rotate relative to the spindle 16, a portion of which comprises the driven clutch member to be described herein, when a limit torque is exceeded.
The driving member 24 includes axially projecting teeth 28 which are cooperable with similar interfitting teeth 30 formed on a drive shaft 32 which is adapted to be driven by the tool motor in a known way. The positive engaging clutch formed by the teeth 28 and 30 becomes engaged in response to axial pressure exerted on the spindle 16 by the tool operator which will move the spindle and the clutch 10 into position to engage the teeth 28 with the teeth 30 on the drive member 32. When this axial pressure is relieved a spring 34 disposed in a bore 36 in the spindle 16 will return the spindle to the position shown in Fig. 1, disengaging the member 24 from the member 32.
Referring to Fig. 2 also, the driving member 24 of the torque limiting clutch is further characterized by an integral axially projecting cylindrical part 38 having an internal cam surface formed by a plurality of equally spaced concavely curved recesses 40 extending radially outwardly with respect to the axis of rota-tion 42 of the spindle 16. The cam surface is further characterized by convex curved portions 44 interposed between adjacent recesses 40 and preferably tangent to the concave curved surfaces at their respective meeting points. Alternatively, the portions 44 may be flat or slightly concave surfaces.
The spindle 16 has an integral rim portion 46 disposed acjacent the internal cam surface on the driving member 24 and having a plurality of radially extending equally spaced grooves 48 which open to the circumference of the rim and also to one transverse face 50 of the rim. As shown in Fig. 2 also, the torque limiting clutch 10 includes spherical balls 52 disposed in each of the grooves 48 which are equal in number to the recesses 40. The balls 52 are retained in the grooves 48 by a ring 54 disposed on --4~
lC~7~100 the spindle 16 and biased into engagement with the balls by a compression coil spring 56. The spring 56 is retained on the spindle 16 by a nut 58 engaged with a threaded portion 60 of the spindle. The compression force exerted by the spring 56 on the ring 54 may be varied by changing the position of the nut.
An axially slidable washer 62 is interposed between the spring 56 and the nut 58 and includes a detent ball 64 which engages a recess 66 in the nut to prevent unwanted rotation thereof with respect to the spindle 16.
The ring 5~ includes an axially sloping or frustoconical surface 66 which is in engagement with the balls 52 and biases the balls radially outwardly into the recesses 40 as shown in Fig. 2. The angle that the surface 66 forms with respect to the axis of rotation 42 of the spindle 16 affects the torque value at which the balls 52 may be forced radially inwardly in the grooves 48 to allow the member 24 to rotate with respect to the spindle 16 to limit the torque transmitted by the clutch. The torque limit setting of the clutch 10 is also controlled, of course, by the compression of the spring 56 and the axial force exerted thereby on the ring 54. The compression of the spring 56 may be adjusted by turning the nut 58 in one direction or the other.
The torque range of the clutch 10 may be extended by inter-changing the ring 54 with, for example, a ring 70 as shown in Fig. 5 which has an axially sloping surface 72 which forms an angle with the central axis of the ring different from the surface 66. Since the force transmitted from the balls 52 to the ring 54 is normal to the surface 66 the axial force component of the net force transmitted to the ring increases with the slope of the surface 66. Accordingly, a ring similar to the ring 54 with a more steeply sloping ball engaging surface will cause the clutch 10 to slip at a lower torque for a given setting of the compression iO7~100 of the spring 56. Accordingly, by merely interchanging the ring 54 with the ring 70 the overall range of torques for which the clutch may be operated may be extended.
In the operation of a hand-held power operated tool including the clutch 10 the clutch formed by the teeth 28 and 30 is engaged by applying axial pressure to the spindle 16 through a bit or the like disposed in the socket 20. When the driving torque of the motor transmitted by the clutch 10 exceeds the limit value the balls 52 are forced radially inwardly in the grooves 48 by the i0 cam surfaces 40 and 44 on the driving member 24 as the ring 54 is forced axially away from the grooves, and the driving member rotates with respect to the spindle 16 which normally stalls at the limit torque. The continued rotation of the driving member 24 imparts gentle reaction impulses to the tool housing which are sensed by the tool operator to indicate that the tool operating cycle is complete. The smooth curved contour of the internal cam surface formed by the recesses 40 and the convex portions 44 eliminates any highly stressed areas on the cam and promotes longer service life of the clutch parts. The cam surfaces on the driving member 24 also reduce the magnitude of the impacts or torque pulses which are transmitted by prior art clutches and which result in inaccurate final torques applied to the fastener.
Referring to Figs. 3 and 4 of the drawings an alternate em-bodiment of a torque limiting clutch in accordance with the present
This invention pertains to improvements in torc~le limiting or overload release clutches of the type which are used in power tools for tightening threaded fasteners and the like. The develop-ment of torque limiting clutches for power tools has resulted in numerous inventions which are generally characterized by a driving clutch member having an external polygonal cam surface and a plurality of drive balls or rollers retained in a driven member in yieldable engagement with the cam surface. At a predetermined torque the balls or rollers ride up and over the peaks of the cam surfaces to allow relative rotation between the driving and driven members to limit the torque output of the tool. The im-pulses caused by the balls riding over the cam peaks are normallysensed by the tool operator and serve as an indication that the limit .orque output of the tool has been achieved. Examples of the types of torque limiting clutches referred to above are dis-closed in U.S. Patents 2,957,323 to C.A. Elliott et al; 2,978,082 ~;~
1079~00 to B.R. Better, and 3,005,325 to R.E. Eckman. A variation of the aforementioned clutch design is disclosed in U.S. Paten~
No. 3,937,036 to W.D. Sauerwein.
In the first three above mentioned patents the driving clutch member is characterized by an external hexagonal cam configuration.
One disadvantage of this type of cam is that the peaks formed by the intersection of the sides of the hexagon are subject to con-centrated stresses which can result in rapid wear and early failure of the mechanism. Other torque limiting clutch designs character-ized b~ members which have sharp edged recesses from which thedrive balls are displaced also have the disadvantage of being subject to rapid wear and causing poor torque control because of the impacts or torque pulses which are delivered to the driven member as the balls or rollers move in and out of the recesses.
SUMMARY OF THE INVENTION
The present invention provides for a torque limiting clutch for a power tool or the like which is operable to allow the tool motor and drive train ahead of the clutch to continue operating when a limit torque has been exceeded without causing excessive wear on the clutch members and while maintaining superior control of the predetermined limit torque over an extensive torque range.
In the torque limiting clutch of the present invention im-proved cperating life of the clutch is realized ~y a design wherein one of the clutch members includes cam surfaces for engagement with a plurality of drive balls which cam surfaces are not subject to concentrated stresses and the rapid wear associated therewith.
In the present invention the driving or driven clutch member may be characterized by a bore having an inner surface geometry or profile which is operable to permit movement of the balls over the cam surfaces at an accurately controlled predetermined torque and with an unexpected improvement in the operating life of the cam.
~ -2-107~100 In accordance with one broad aspect, the invention relates to a torque limiting clutch for use in a power operated tool for tightening threaded fasteners and the like, said clutch including: a rotatable driven member; a driving member rotatable with respect to said driven member at a predetermined torque transmitted by said clutch to a driven spindle; one of said members being characterized by a continuously curved internal cam surface including a plurality of spaced apart recesses extending radially outwardly with respect to the axis of rotation of said spindle and in a plane perpendicular to the axis of rotation of said one member said recesses are formed by substantially concave curved surface portions which are interconnected by substantially convex curved surface portions disposed radially inwardly of said concave curved surface portions with respect to the axis of rotation of said one member; the other of said members including a radially, outwardly extending rim having at least one transverse face and a plurality of radially extending grooves in said rim opening to said face and being spaced apart so as to be respectively alignable with said recesses; movable elements disposed in said grooves and operable to be biased radially outwardly into said recesses for coupling said driving and driven members for rotation together to transmit torque to said spindle; a third member having a surface disposed adjacent said transverse face on said other member and engaged with said movable elements; and, resilient means engaged with said third member for causing said third member to yieldably urge said movable elements into said recesses in said one member and whereby at a predetermined limit torque said elements are forced radially inwardly in said grooves by said cam surface to allow said driving member to rotate with respect to said driven member.
iO79100 One embodiment of the present invention also provides a torque limiting clutch which may be adapted to operate over a large range of limiting torques by interchanging an inexpensive member of the clutch assembly.
The present invention further provides for a torque limiting clutch which has a relatively few working parts, is inexpensive, and is easy to manufacture.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a lcngi~udinal sectional view of one embodiment of a torque limiting clutch of the present invention;
Fig. 2 is a section view taken along the line 2-2 of Fig. l;
Fig. 3 is a longitudinal sectional view of an alternate em-bodiment of the torque limiting clutch;
Fig. 4 is a section view taken along the line 4-4 of Fig. 3;
and, Fig. 5 is a perspective view of an alternate torque control ring for use with the clutch embodiment shown in Figs. 1 and 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Fig. 1 a torque limiting clutch in accordance with the present invention is generally designated by the numeral 10 and is shown disposed in a housing 12 comprising a portion of a power tool for tightening threaded fasteners and the like. The housing 12 is adapted to be removably connected to a tool motor unit, not shown, in a conventional manner. The housing 12 includes a bore 14 comprising bearing means for supporting a rotatable spindle 16. The spindle 16 includes a removable sleeve 18 having a polygonal bore 20 engaged with one end of the spindle and adapted to receive a tool bit or the like, not shown. The opposite end of the spindle 16 includes a cylindrical bearing portion 22 on which is mounted a driving member 24 of the torque limiting clutch 10.
The member 24 is retained on the bearing portion 22 by a retaining iO79100 ring 26 and is operable to rotate relative to the spindle 16, a portion of which comprises the driven clutch member to be described herein, when a limit torque is exceeded.
The driving member 24 includes axially projecting teeth 28 which are cooperable with similar interfitting teeth 30 formed on a drive shaft 32 which is adapted to be driven by the tool motor in a known way. The positive engaging clutch formed by the teeth 28 and 30 becomes engaged in response to axial pressure exerted on the spindle 16 by the tool operator which will move the spindle and the clutch 10 into position to engage the teeth 28 with the teeth 30 on the drive member 32. When this axial pressure is relieved a spring 34 disposed in a bore 36 in the spindle 16 will return the spindle to the position shown in Fig. 1, disengaging the member 24 from the member 32.
Referring to Fig. 2 also, the driving member 24 of the torque limiting clutch is further characterized by an integral axially projecting cylindrical part 38 having an internal cam surface formed by a plurality of equally spaced concavely curved recesses 40 extending radially outwardly with respect to the axis of rota-tion 42 of the spindle 16. The cam surface is further characterized by convex curved portions 44 interposed between adjacent recesses 40 and preferably tangent to the concave curved surfaces at their respective meeting points. Alternatively, the portions 44 may be flat or slightly concave surfaces.
The spindle 16 has an integral rim portion 46 disposed acjacent the internal cam surface on the driving member 24 and having a plurality of radially extending equally spaced grooves 48 which open to the circumference of the rim and also to one transverse face 50 of the rim. As shown in Fig. 2 also, the torque limiting clutch 10 includes spherical balls 52 disposed in each of the grooves 48 which are equal in number to the recesses 40. The balls 52 are retained in the grooves 48 by a ring 54 disposed on --4~
lC~7~100 the spindle 16 and biased into engagement with the balls by a compression coil spring 56. The spring 56 is retained on the spindle 16 by a nut 58 engaged with a threaded portion 60 of the spindle. The compression force exerted by the spring 56 on the ring 54 may be varied by changing the position of the nut.
An axially slidable washer 62 is interposed between the spring 56 and the nut 58 and includes a detent ball 64 which engages a recess 66 in the nut to prevent unwanted rotation thereof with respect to the spindle 16.
The ring 5~ includes an axially sloping or frustoconical surface 66 which is in engagement with the balls 52 and biases the balls radially outwardly into the recesses 40 as shown in Fig. 2. The angle that the surface 66 forms with respect to the axis of rotation 42 of the spindle 16 affects the torque value at which the balls 52 may be forced radially inwardly in the grooves 48 to allow the member 24 to rotate with respect to the spindle 16 to limit the torque transmitted by the clutch. The torque limit setting of the clutch 10 is also controlled, of course, by the compression of the spring 56 and the axial force exerted thereby on the ring 54. The compression of the spring 56 may be adjusted by turning the nut 58 in one direction or the other.
The torque range of the clutch 10 may be extended by inter-changing the ring 54 with, for example, a ring 70 as shown in Fig. 5 which has an axially sloping surface 72 which forms an angle with the central axis of the ring different from the surface 66. Since the force transmitted from the balls 52 to the ring 54 is normal to the surface 66 the axial force component of the net force transmitted to the ring increases with the slope of the surface 66. Accordingly, a ring similar to the ring 54 with a more steeply sloping ball engaging surface will cause the clutch 10 to slip at a lower torque for a given setting of the compression iO7~100 of the spring 56. Accordingly, by merely interchanging the ring 54 with the ring 70 the overall range of torques for which the clutch may be operated may be extended.
In the operation of a hand-held power operated tool including the clutch 10 the clutch formed by the teeth 28 and 30 is engaged by applying axial pressure to the spindle 16 through a bit or the like disposed in the socket 20. When the driving torque of the motor transmitted by the clutch 10 exceeds the limit value the balls 52 are forced radially inwardly in the grooves 48 by the i0 cam surfaces 40 and 44 on the driving member 24 as the ring 54 is forced axially away from the grooves, and the driving member rotates with respect to the spindle 16 which normally stalls at the limit torque. The continued rotation of the driving member 24 imparts gentle reaction impulses to the tool housing which are sensed by the tool operator to indicate that the tool operating cycle is complete. The smooth curved contour of the internal cam surface formed by the recesses 40 and the convex portions 44 eliminates any highly stressed areas on the cam and promotes longer service life of the clutch parts. The cam surfaces on the driving member 24 also reduce the magnitude of the impacts or torque pulses which are transmitted by prior art clutches and which result in inaccurate final torques applied to the fastener.
Referring to Figs. 3 and 4 of the drawings an alternate em-bodiment of a torque limiting clutch in accordance with the present
2~ invention is shown and generally designated by the numeral 80. The torque limiting clutch 80 is disposed in a housing 82 including bearing means 84 for supporting a rotatable and axially slidable spindle 86. The spindle 86 includes a socket 88 for receiving the shank of a screwdriver bit or the like, not shown. The spindle 86 also includes an axially projecting trunnion 88 which partially supports a rotatable shaft 90 adapted to be suitably connected to a motor, not shown. A coil spring 92 disposed in a bore 94 iO79100 in the shaft 90 biases the axially slidable spindle 86 in the position shown in Fig. 3.
In the clutch embodiment of Figs. 3 and 4 a driven clutch member 96 is mounted on the shaft 90 and is rotatable with respect to the shaft on suitable bearing balls 98 disposed in cooperating grooves on the shaft and the driven member, respectively. The member 96 is characterized by an axially extending cylindrical portion 100 having an internal cam surface formed by concavely curved recesses 102 which are spaced apart equidistant from each other and are interconnected by flat surface portions 104. The cam surface on the driven member 100 is disposed around a radially extending rim 106 on the shaft 90 which includes a plurality of equally spaced grooves 108 equal in number to the recesses 102.
The grooves 108 open to the circumference of the rim 106 and also to a transverse face 110 of the rim. As shown in Fig. 3 the grooves 108 have an inclined bottom surface 112 which intersects the face 110 and the circumference of the rim 106.
The clutch 80 is further characterized by a flat sided ring 114 which is disposed adjacent to the face 110 and is biased toward the face by a coil spring 116 disposed around the shaft 90.
The spring 116 is retained on the shaft by a washer 62 and a nut 58 whereby the compression of the spring may be varied to control the limit tor~ue of the clutch 80 in the same manner as the clutch 10. The ring 114 is engaged with spherical balls 118 disposed one in each of the grooves 108. The balls 118 are biased radially outwardly to be seated in the recesses 102 by the force of the spring 116 acting through the ring 114.
The clutch embodiment shown in Figs. 3 and 4 includes a posi-tive engaging clutch comprising axially projecting interfitting teeth 120 and 122 disposed on the spindle 86 and the clutch member 96.
iO79100 The operation of the clutch 80 is similar to the clutch 10 shown in Figs. 1 and 2. With the teeth 120 and 122 interengaged, as a result of axial force applied to the spindle 6, the member 96, shaft 90 and the spindle may be rotated in unison. At a pre-determined limit torque the balls 118 will move radially inwardlyin the grooves 108 as they are forced out of the recesses 102 and along the flat surface portions 104. The shaft 90 may then con-tinue to rotate while a gentle impulse action is sensed by the operator of the tool to indicate that a limiting torque has been applied to the spindle 86. The clutch 30 includes the advantages of the embodiment shown in Figs. 1 and 2. The internal cam sur-face formed by the concavely curved recesses 102 and the inter-connecting f-lat surface portions 104 does not have any sharp projections or portions which are highly stressed. Moreover, the contour of the cam surface reduces the sharp impacting and torque variations normally encountered with prior art torque limiting clutches.
L ~
In the clutch embodiment of Figs. 3 and 4 a driven clutch member 96 is mounted on the shaft 90 and is rotatable with respect to the shaft on suitable bearing balls 98 disposed in cooperating grooves on the shaft and the driven member, respectively. The member 96 is characterized by an axially extending cylindrical portion 100 having an internal cam surface formed by concavely curved recesses 102 which are spaced apart equidistant from each other and are interconnected by flat surface portions 104. The cam surface on the driven member 100 is disposed around a radially extending rim 106 on the shaft 90 which includes a plurality of equally spaced grooves 108 equal in number to the recesses 102.
The grooves 108 open to the circumference of the rim 106 and also to a transverse face 110 of the rim. As shown in Fig. 3 the grooves 108 have an inclined bottom surface 112 which intersects the face 110 and the circumference of the rim 106.
The clutch 80 is further characterized by a flat sided ring 114 which is disposed adjacent to the face 110 and is biased toward the face by a coil spring 116 disposed around the shaft 90.
The spring 116 is retained on the shaft by a washer 62 and a nut 58 whereby the compression of the spring may be varied to control the limit tor~ue of the clutch 80 in the same manner as the clutch 10. The ring 114 is engaged with spherical balls 118 disposed one in each of the grooves 108. The balls 118 are biased radially outwardly to be seated in the recesses 102 by the force of the spring 116 acting through the ring 114.
The clutch embodiment shown in Figs. 3 and 4 includes a posi-tive engaging clutch comprising axially projecting interfitting teeth 120 and 122 disposed on the spindle 86 and the clutch member 96.
iO79100 The operation of the clutch 80 is similar to the clutch 10 shown in Figs. 1 and 2. With the teeth 120 and 122 interengaged, as a result of axial force applied to the spindle 6, the member 96, shaft 90 and the spindle may be rotated in unison. At a pre-determined limit torque the balls 118 will move radially inwardlyin the grooves 108 as they are forced out of the recesses 102 and along the flat surface portions 104. The shaft 90 may then con-tinue to rotate while a gentle impulse action is sensed by the operator of the tool to indicate that a limiting torque has been applied to the spindle 86. The clutch 30 includes the advantages of the embodiment shown in Figs. 1 and 2. The internal cam sur-face formed by the concavely curved recesses 102 and the inter-connecting f-lat surface portions 104 does not have any sharp projections or portions which are highly stressed. Moreover, the contour of the cam surface reduces the sharp impacting and torque variations normally encountered with prior art torque limiting clutches.
L ~
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A torque limiting clutch for use in a power operated tool for tightening threaded fasteners and the like, said clutch including:
a rotatable driven member;
a driving member rotatable with respect to said driven member at a predetermined torque transmitted by said clutch to a driven spindle;
one of said members being characterized by a continuously curved internal cam surface including a plurality of spaced apart recesses extending radially outwardly with respect to the axis of rotation of said spindle and in a plane perpendicular to the axis of rotation of said one member said recesses are formed by substantially concave curved surface portions which are interconnected by substantially convex curved surface portions disposed radially inwardly of said concave curved surface portions with respect to the axis of rotation of said one member;
the other of said members including a radially, outwardly extending rim having at least one transverse face and a plurality of radially extending grooves in said rim opening to said face and being spaced apart so as to be respectively alignable with said recesses;
movable elements disposed in said grooves and operable to be biased radially outwardly into said recesses for coupling said driving and driven members for rotation together to transmit torque to said spindle;
a third member having a surface disposed adjacent said transverse face on said other member and engaged with said movable elements; and, resilient means engaged with said third member for causing said third member to yieldably urge said movable elements into said recesses in said one member and whereby at a predetermined limit torque said elements are forced radially inwardly in said grooves by said cam surface to allow said driving member to rotate with respect to said driven member.
a rotatable driven member;
a driving member rotatable with respect to said driven member at a predetermined torque transmitted by said clutch to a driven spindle;
one of said members being characterized by a continuously curved internal cam surface including a plurality of spaced apart recesses extending radially outwardly with respect to the axis of rotation of said spindle and in a plane perpendicular to the axis of rotation of said one member said recesses are formed by substantially concave curved surface portions which are interconnected by substantially convex curved surface portions disposed radially inwardly of said concave curved surface portions with respect to the axis of rotation of said one member;
the other of said members including a radially, outwardly extending rim having at least one transverse face and a plurality of radially extending grooves in said rim opening to said face and being spaced apart so as to be respectively alignable with said recesses;
movable elements disposed in said grooves and operable to be biased radially outwardly into said recesses for coupling said driving and driven members for rotation together to transmit torque to said spindle;
a third member having a surface disposed adjacent said transverse face on said other member and engaged with said movable elements; and, resilient means engaged with said third member for causing said third member to yieldably urge said movable elements into said recesses in said one member and whereby at a predetermined limit torque said elements are forced radially inwardly in said grooves by said cam surface to allow said driving member to rotate with respect to said driven member.
2. The invention set forth in claim 1 wherein said spindle includes an axially extending cylindrical portion comprising bearing means for rotatably supporting said driving member.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US89486878A | 1978-04-10 | 1978-04-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1079100A true CA1079100A (en) | 1980-06-10 |
Family
ID=25403612
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA315,769A Expired CA1079100A (en) | 1978-04-10 | 1978-11-03 | Torque limiting clutch |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1079100A (en) |
| GB (1) | GB2018368A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3023541C1 (en) * | 1980-06-24 | 1981-10-01 | Uni-Cardan Ag, 5200 Siegburg | Overload clutch |
| DE3230817C2 (en) * | 1982-08-19 | 1985-05-09 | Jean Walterscheid Gmbh, 5204 Lohmar | Safety ratchet clutch |
| US5005684A (en) * | 1988-12-03 | 1991-04-09 | Tsubakimoto Emerson Co. | Overload clutch |
| GB9716166D0 (en) * | 1997-08-01 | 1997-10-08 | British Autogard | Torque limiting clutch |
| CN1107817C (en) * | 1999-05-31 | 2003-05-07 | 王胜 | Multi-function coupling |
| JP5171619B2 (en) | 2005-06-23 | 2013-03-27 | トムソン ライセンシング | Portable playback device, method and system compatible with digital rights management (DRM) |
| US8382595B2 (en) | 2009-06-15 | 2013-02-26 | Neapco Llc | Torque limiting driveline |
-
1978
- 1978-11-03 CA CA315,769A patent/CA1079100A/en not_active Expired
- 1978-11-15 GB GB7844666A patent/GB2018368A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB2018368A (en) | 1979-10-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |