A CLUTCH

THIS INVENTION relates to a clutch.

The invention is to be used in the context of protecting rotary motors and/or rotationally driven components against damage arising from torque overload conditions.

In accordance with the invention there is provided a clutch which includes: a housing; an input clutch component located in the housing, the clutch being provided with a connection formation for rotatingly connecting an output shaft of a rotary drive to the input clutch component; an output clutch component located in the housing, the clutch being provided with a connection formation for connecting an input shaft of a rotationally driven component to the output clutch component; at least one coupling element located in the housing and arranged for interacting with the input clutch component and the output clutch component, each coupling element having a coupling condition in which it rotatingly couples the input clutch component and the output clutch component, to permit transmission of rotary motion from the input clutch component to the output clutch component, and an uncoupled condition in which it resists transmission of rotary motion from one of the input clutch component and the output clutch component to the other one of said clutch components; and an urging arrangement located in the housing, the urging arrangement permanently urging each coupling element towards its coupling condition, the urging arrangement and each coupling element being arranged such that when torque transmitted from one of the input clutch component and the output clutch component to the other one of said clutch components exceeds a predetermined maximum, each

coupling element automatically assumes its uncoupled condition, so that transmission of rotary motion between the clutch components is resisted.

The clutch may have a rotation axis, the connection formations associated with the output clutch component and with the input clutch component being arranged such that an output shaft of a rotary drive and an input shaft of a rotationally driven component connected to the respective connection formations are co-axial with the rotation axis of the clutch.

One of the input clutch component and the output clutch component may be irrotatably received in the housing, such that the housing, in use, rotates with said one of the input clutch component and the output clutch component, the other one of the input clutch component and the output clutch component being rotatably supported in the housing, such that with each coupling element in its coupling condition, said other one of the input clutch component and the output clutch component rotates with the housing about the rotation axis, and with each coupling element in its uncoupled condition, the housing and said rotatably supported clutch component rotate relative to each other about the rotation axis. Each clutch component thus rotates, when applicable, about the rotation axis of the clutch.

Said one of the input clutch component and the output clutch component which is irrotatably received in the housing may be slideably received in the housing for sliding along the rotation axis of the clutch, such that it is moveable along said rotation axis relative to the other one of the input clutch component and the output clutch component, with the urging arrangement acting on said one of the input clutch component and the output clutch component which is slideably received in the housing, each coupling element being located between the two clutch components, and the urging arrangement being arranged to urge said slideably received one of the input clutch component and the output clutch component and, accordingly each coupling element, towards the other one of the input clutch component and the output clutch component.

The housing and said slideably received clutch component may be provided with complementary slide formations, the slide formations interacting with each other to

permit sliding of the slideably received clutch component along the rotation axis of the clutch relative to the housing.

The input clutch component and the output clutch component may each define a coupling face, the input clutch component and the output clutch component being arranged such that their coupling faces face each other, and each coupling element being in the form of a roller element located between the coupling faces of the clutch components, the coupling faces of the input and output clutch components being provided with complementary recesses or seats radially spaced from the rotation axis of the clutch for receiving or seating each roller element when the roller element is in its coupling condition, and the coupling face of one of the components being provided with an annular track surrounding the rotation axis of the clutch and connecting each recess or seat provided in said coupling face, the annular track being shallower than each recess or seat in its associated coupling face, such that each roller element is moved from its recess or seat to run along the track when in its uncoupled condition.

The clutch may include a plurality of coupling elements, the coupling faces of the input and the output components each being provided with a like plurality of recesses or seats that are circumferentially spaced about the rotation axis of the clutch. Each coupling element may be in the form of a ball bearing.

The urging arrangement may include an urging face provided by said one of the input clutch component and the output clutch component which is slideably received in the housing or by a component fast therewith, the urging face facing in the opposite direction than the coupling face of said one of the input and output clutch components, and at least one spring acting on and held captive under compression between the housing and the urging face.

The sliding formations of the housing may be in the form of a plurality of elongated sliding pins fast with the housing, the sliding pins having longitudinal axes which are spaced from and parallel to the rotation axis of the clutch, the sliding formations of said slideably received clutch component being in the form of openings spaced from the rotation axis of the clutch, with one said spring being received over

each sliding pin, and a free end of each sliding pin being received through one of the openings in said clutch component.

The input clutch component may be irrotatably and slideably received in the housing, the output clutch component being rotatably supported in the housing.

The urging arrangement may be arranged to permit adjustment of an urging force exerted thereby on each coupling element, so that said predetermined maximum torque transferable between the two clutch components is adjustable.

The clutch may include an adjustment arrangement for adjusting the urging force exerted by the urging arrangement on each coupling element for permitting said adjustment of the predetermined maximum transferable torque.

The housing may be of two-part construction, the connection formation associated with the input clutch component being fast with or provided by one part of the housing, the connection formation associated with the output clutch component being fast with or provided by the other part of the housing, the housing being constructed such that the two parts thereof are moveable relative to each other along the rotation axis of the clutch to provide for adjustment of the urging force exerted by the springs.

The two parts of the housing may be screw threadedly connected to the other part of the housing, such that said relative movement of the two parts is effected via said screw threaded connection. In one embodiment, the clutch may also include an electrically operated mechanism mounted on the housing for effecting relative movement of the tow parts of the housing. The electrically operated mechanism may be a remote controlled mechanism, and may include an electrical motor.

The clutch may which include a torque overload sensing arrangement mounted on the housing for sensing when each coupling element is in its uncoupled condition.

The invention extends to a drive arrangement, the drive arrangement including a rotary drive having an output shaft, a driven component having an input shaft, and a clutch drivingly connecting the output shaft of the rotary drive and the input shaft of the driven component for transferring rotational motion from the rotary drive to the driven component, the clutch being a clutch as hereinbefore described.

The invention is now described, by way of non-limiting example, with reference to the accompanying diagrammatic drawings.

In the drawings:

Figure 1 shows, schematically, a drive arrangement including a clutch in accordance with the invention;

Figure 2 shows, schematically, an end elevation of the clutch in accordance with the invention; Figure 3 shows, schematically, an axial sectional elevation of the clutch in accordance with the invention, the section being taken at III - III in Figure 2, the clutch being shown with coupling elements thereof in coupled conditions;

Figure 4 shows, schematically, an axial sectional elevation of the clutch in accordance with the invention corresponding to that shown in Figure 3, the clutch being shown with the coupling elements thereof in uncoupled conditions;

Figure 5 shows, schematically, a face-on elevation of an output clutch component forming part of the clutch in accordance with the invention;

Figure 6 shows, schematically, a sectional side elevation of the output clutch component shown in Figure 5, the section being taken at Vl - Vl in Figure 5; and Figure 7 shows, schematically, a face-on elevation of an input clutch component forming part of the clutch in accordance with the invention.

With reference to Figure 1 of the drawings, a drive arrangement which includes a clutch in accordance with the invention is generally designated by reference numeral 10. The drive arrangement 10 includes a rotary motor 12 (shown in concept only) having an output shaft 14. The drive arrangement 10 further includes a rotationally driven component 16 (also shown in concept only) having an input shaft 18. The output shaft 14 of the rotary motor 12 is drivingly connected to the input shaft 18 of the rotationally driven component 16 by means of the clutch, designated by reference

numeral 20, in accordance with the invention, so that the motor 12 drives the component 16 via the clutch 20. The clutch 20 is shown in concept only in Figure 1 , but shown in greater detail in further figures.

The clutch 20, as will become more apparent hereunder, is arranged to transmit rotational motion from the rotary motor 12 to the rotationally driven component 16 during normal operating conditions of the drive system 10, and is arranged to resist transmission of rotary motion from the rotary motor 12 to the rotationally driven component 16 during torque overload conditions, thereby protecting both the rotary motor 12 and the rotationally driven component 16 against damage arising from torque overload conditions. In other words, the clutch 20 rotationally couples the motor 12 and the rotationally driven component 16 during normal operating conditions, and rotationally uncouples them during torque overload conditions. As described in detail hereunder, the clutch 20 permits, in accordance with requirements of a particular application, adjustment of the maximum torque that can be transmitted thereby between the motor 12 and the rotationally driven component 16.

The clutch 20 includes a housing 22 defining a hollow circular cylindrical interior. The housing 22 is of two-part construction, comprising a roughly cup-shaped shell 24 having one open end, and a closure disc 26 closing said open end of the shell 24. The shell 24, at its open end is provided with an internal screw thread 27, and the disc 26 is provided with an external screw thread 28, by means of which screw threads 27, 28 the two parts of the housing 22 are releasably connected together.

The clutch 20 includes an input clutch component in the form of a squat cylinder or input disc 30 (hereinafter referred to as the input disc 30). The input disc 30 is irrotatably, i.e. relative to the housing 22, received or located in the shell 24 of the housing 22 and radiates outwardly from a rotation axis 32 of the clutch 20. The shell 22 at its end opposite from its open end is provided with an outwardly projecting, centrally located connection formation 33 defining a passage 34 which is circular cylindrical and is concentric about the rotation axis 32 of the clutch for receiving the output shaft 14 of the rotary motor 12. The shaft 14 is, in use, secured to the connection formation 34 by means of a key 35.

The input disc 30 is, as mentioned, irrotatably received in the housing 22, but is arranged such that displacement or movement thereof along the rotation axis 32 relative to the shell 24 is permitted. Said movement is enabled by sliding formations which are described in more detail hereunder.

The clutch 22 further includes an output clutch component in the form of a squat cylinder or output disc 36 (hereinafter referred to as the output disc 36), the output disc 36 also being located in the housing 22. The output disc 36 is provided with an output shaft connection formation for connecting the input shaft 18 of the rotationally driven component 16 thereto. In this example, the connection formation is in the form of a stub shaft 38 projecting form the disc 36. In this example, the shaft 38 is shown as being integrally formed with the disc 36. It is to be appreciated that, in other examples, the shaft 38 and the disc 36 can be separate components which are merely connected together. In such examples, the disc 36 will be provided with a central opening for receiving one end of the shaft 38. As will be appreciated, in such examples, the input shaft 18 will be secured to the output disc 36 by means of a key or other securing formation. In use, as shown in Figure 1 , the shaft 38 is rotationally connected to the input shaft 18 of the rotationally driven component 16 by means of a coupling 39 (also shown in concept only).

To permit passing of the shaft 38, the disc 26 is provided with a central opening 40, which passes the shaft 38 with clearance. As can be seen, a free end of the shaft 38 projects from the housing 22.A roller bearing 42 is received over the shaft 38, the bearing 42 rotatingly supporting the shaft 38 and being located on an exterior of the housing 22. The bearing 42 is covered by a cap 44 secured to the disc 26. The cap 44 is provided with a central opening 45 concentric about the rotation axis 32 of the clutch 20, which opening 45 passes the shaft 38 with rotating clearance. Although not shown as such, a seal can be provided between the cap 44 and the shaft 38 for resisting contamination of the bearing 42. The output disc 36 is thus rotatably received in the housing 22, and it is fixed against movement along the rotation axis 32.

The input disc 30 is provided with a coupling face 46, which coupling face is substantially flat, and the output disc 36 is provided with a substantially similar coupling

face 48, the coupling faces 46, 48 being spaced from each other along the rotation axis 32 and facing each other.

Referring now in particular to Figure 5 of the drawings, a face-on elevation of the coupling face 48 of the output disc 36 is shown. The output disc 36, on its coupling face 48, is provided with a plurality of, in this example eight, dome-shaped recesses or seats 50. The recesses or seats 50 are circumferentially spaced around the rotation axis 32, and each recesses or seat 50 is somewhat shy of being semi-spherical. An annular track 52 intrudes into the coupling face 48 of the disc 36, the annual track 52 being shallower than the recesses or seats 50 and connecting the recesses or seats 50 together.

Turning now in particular to Figure 7, which shows an axial face-on elevation of the input disc 30, the input disc 30 is provided with eight semi-spherical recesses or seats 54, the recesses or seats 54 being circumferentially spaced about the rotation axis 32. The spacing of the recesses or seats 50 and the recesses or seats 54 are such that they can be aligned, as will become more apparent hereunder.

The clutch 20 further includes a plurality of coupling elements, in this example eight, each of which is in the form of a ball bearing 56. Each ball bearing 56 is displaceable between a coupling condition in which it is received in aligned recesses or seats 50, 54, to couple the input disc 30 to the output disc 36, and an uncoupled condition in which it is unseated from the associated seat 50. For illustrative purposes, the ball bearings 56 are shown as being somewhat loosely received in the recesses 50, 54. In practice, they will be snugly received in the recesses 50, 54. When the ball bearings 56 are in their coupling conditions, transmission of rotary motion, and accordingly torque, from the rotary motor 12 to the rotationally driven component 16 is permitted. In turn, as will become more apparent hereunder, when a torque overload condition exists, each ball bearing 56 is displaced into its uncoupled condition, in which uncoupled condition transmission of rotary motion, and accordingly torque, from the rotary motor 12 to the rotationally driven component 16 is resisted. When assuming its uncoupled condition, each ball bearing 56 is, by virtue of the recesses or seats 50 being shallower than the recesses or seats 54, unseated from its recess or seat 50 and caused to roll along the annular track 52.

The clutch 20 includes an urging arrangement which permanently causes each bearing 56 to be urged towards its coupling condition. The urging arrangement includes an urging plate 58 which provides an urging face 59. The urging plate, which is also in the form of a disc, is connected to the disc 30. The urging face 59 faces in the opposite direction than the coupling face 46 of the disc 30. Although the input disc 30 and the urging plate 58, in the illustrated example, are tow components which are connected together, it is to be appreciate that, in other examples, they can be integrally formed with each other to form a single component, the urging plate portion of said component being in the form of a flange radiating from the disc portion of said single component. In such examples, the urging face 59 will thus be provided by the input disc 30.

Six circumferentially spaced sliding pins 60 are mounted on the interior of the shell 24, the pins 60 being mounted on a wall of the shell 24 providing its closed end. Longitudinal axes of the pins 60 are parallel to one another and parallel to the rotation axis 32 of the clutch 20. The urging plate 58, in turn, is provided with six openings 62 through which free end portions of the pins 60 are slideably received. The urging plate 58 and the input disc 30 is thus slidable relative to the pins 60, so that the input disc, although irrotatably mounted on the housing 20, is slideable relative thereto along the rotation axis 32. The pins 60 and the openings 62 define slide formations permitting said movement of the input disc 30 along the rotation axis 32. Further, a coil spring 64 is received over each sliding pin 60, the springs 64 being held captive between and acting on the wall providing the closed end of the shell 24 and the urging plate 58. The springs 64 are arranged to be under compression, so that they permanently urge the input disc 30 towards the output disc 36, thereby urging each ball bearing into its coupling condition.

In use when a torque overload condition exists, each ball bearing will be unseated form its associated recess 50, causing the springs 64 to be compressed and the input disc 30 to move away form the output disc 36, and roll along the track 52. When it reaches the next recess 50, each ball bearing 56 will, if the torque overload condition has ceased to exist, by virtue of an urging force exerted by the springs 64, be seated in said recess 50 and remain there, so that rotary motion can again be transferred. In turn, if the torque overload condition still exists, each bearing 56 will

continue to roll along the track 52. Thus, in use, if a torque overload condition ceases to exist, the clutch 20 will automatically resume to transfer rotary motion. Thus, upon a torque overload condition, the clutch 20 will slip.

The clutch 20 further includes an adjustment arrangement for adjusting the urging force exerted by the springs 60 on the input disc 30. The adjustment arrangement is constituted by the screw threads 27, 28 of the shell 24 and the disc 26. By threading the disc 26 deeper into the interior of the shell 24, the compression under which the springs 64 are held is increased, i.e. the urging force exerted thereby is increased, so that said maximum torque which can be transferred is increased. In turn, by loosening the disc 26, the compression under which the springs are held is decreased, thereby lowering the maximum torque which can be transmitted.

As mentioned above, during normal operating conditions, each of the ball bearings 56 is in its coupled condition, so that the input disc 30 is coupled to the output disc 36, thereby permitting transmission of rotary movement, and accordingly torque, from the rotary motor 12 to the rotationally driven component 16. In turn, when a torque overload condition occurs, such as for example when the rotationally driven component

16 malfunctions in a fashion which resists rotation thereof, the torque transmitted from the disc 30 to the disc 36 will overcome the urging force exerted by the springs 64 and, accordingly, transfer of rotary motion is resisted, thereby protecting the motor 12 against overload. With each bearing 56 in its uncoupled condition, transfer of rotary motion from the output disc 36 to the input disc 30 is thus also resisted. The clutch 20 thus also acts to protect the rotary motor 12 against damage arising from torque overload conditions caused by the rotationally driven component 16. For example when the motor malfunctions in a fashion which resists rotation thereof and the rotationally driven component 16, by virtue of inertia, transmits or attempts to transmit rotary motion to the motor 12, the clutch 20 will resist transmission of rotary motion to the motor 12.

The clutch 20 in some examples, but not in the shown example, can further be provided with a sensor mounted on the housing 22 and arranged to sense when each ball bearing 56 assumes its uncoupled condition, i.e. the sensor senses when the clutch slips upon torque overload conditions. The sensor can be connected to any communication means, for example an alarm or a transmitter, for communicating

existence of a torque overload condition to a monitoring device or authority. Said communication can take place wirelessly.

The invention as described and illustrated thus provides a clutch which protects a rotary drive and/or a rotationally driven component against damage arising from torque overload conditions. By virtue of the particular construction of the clutch, adjustment of a maximum permissible torque which can be transmitted from a rotary motor to a rotationally driven component, or vice versa, can be adjusted. Further, by virtue of the construction of the clutch as described and illustrated, the clutch, after a torque overload condition ceases to exist, automatically again provides for transmission of rotary motion from a rotary motor to a rotationally driven component.