Rotary shafts – gudgeons – housings – and flexible couplings for ro – Overload release coupling – Torque transmitted via frictional engagement of planar...
Reexamination Certificate
1999-02-16
2001-08-28
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Overload release coupling
Torque transmitted via frictional engagement of planar...
Reexamination Certificate
active
06280331
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a cable reel drive assembly and, more particularly, is concerned with a torque limiting slip clutch apparatus and a cable reel drive assembly employing the slip clutch apparatus.
2. Description of the Prior Art
Motor-driven constant-torque reel drive assemblies are used in various industrial applications where cables and hoses of varying lengths reeled out from a stationary source of supply are needed to provide power and control to machinery and equipment that move relative to the stationary supply source. As used hereafter, the term “cable” is meant to include within the scope of its definition electrical cables, hydraulic hoses and the like.
Well-known examples of where such reel drive assemblies are used are levelwind and monospiral cable reels commercially available from Gleason Reel Corp. of Mayville, Wis., a subsidiary of Hubbell Corporation. The levelwind and monospiral cable reels are used in conjunction with the operation of container and raw material handling cranes for unloading ships. The levelwind cable reel stores cable in, and thus pays out cable from, a side-by-side single-layer configuration of cable on the reel. The monospiral reel stores cable in, and thus pays out cable from, a single multiple-layer configuration of cable on the reel.
There are various factors which can adversely affect the operational efficiency of a cable reel drive assembly. These factors include different rotation speed and output torque requirements during cable payout as opposed to cable rewind and the inertia effects of various components on cable tension during cable payout in response to machinery accelerations. Consequently, a need still remains for innovations to a cable reel drive assembly which will give due consideration to these factors and thereby reduce their adverse impact on operational efficiency of the cable reel drive assembly.
SUMMARY OF THE INVENTION
The present invention provides a torque limiting slip clutch apparatus and a cable reel drive assembly employing the slip clutch apparatus designed to satisfy the aforementioned need. The slip clutch apparatus of the present invention accommodates the different rotational speed and output torque requirements during cable payout as opposed to cable rewind when the operation of a drive motor is not needed and thus shutoff during cable payout. The shutoff of the drive motor operation enables the slip clutch to function as a slip brake restraining the rotation of a cable supply spool to the speed at which the cable is pulled from the spool by the movement of machinery connected to the cable and to function as a holding brake preventing further rotation of the cable supply spool when movement of the machinery has ceased. The slip clutch apparatus of the present invention also isolates and prevents any torque forces (referred inertia) required to accelerate components of the drive assembly from reaching the cable supply spool and cable thereon so that such torque forces are not translated as tension in the cable. By reducing cable tension the spoke size of the cable supply spool can be reduced which, in turn, lowers spool inertia requiring a lower drive torque (or rotary force) to rotate the spool. The lower torque drive, in turn, means even lower cable tension. The combined effect of these reductions is to increase the overall efficiency of the cable reel drive assembly.
Accordingly, the present invention is directed to a torque limiting slip clutch apparatus for use in a cable reel drive assembly. The slip clutch apparatus comprises: (a) an elongated drive shaft mounted to undergo rotational movement; (b) an annular rotary drive member mounted about the drive shaft to undergo rotational movement relative to the drive shaft and translational movement along the drive shaft; (c) an annular drive plate fixed mounted about the drive shaft adjacent to the rotary drive member to undergo rotational movement with the drive shaft and relative to the rotary drive member; (d) means mounted between and engagable with the rotary drive member and drive plate for generating friction therebetween that reduces the rotational movement of the drive plate and drive shaft relative to the rotary drive member in response to translational movement of the rotary drive member along the drive shaft toward the drive plate; and (e) means mounted along the drive shaft adjacent to a side of the rotary drive member opposite from the drive plate for generating a biasing force against the rotary drive member to cause translational movement of the rotary drive member along the drive shaft toward the drive plate and generation of friction between the rotary drive member and drive plate. The slip clutch apparatus further comprises a torque adjustment mechanism disposed adjacent to the biasing force generating means and being operable to adjust the size of the biasing force generated by the biasing force generating means.
The present invention also is directed to a cable reel drive assembly which comprises: (a) a rotary power source operable to provide rotary drive motion at a predetermined input speed; (b) a cable supply spool storing a cable and being rotatable to payout and rewind the cable; and (c) a speed reducer unit disposed between and drivingly connecting the rotary power source to the cable supply spool. The speed reducer unit is operable in cable payout and rewind rotation modes to cause the cable supply spool to correspondingly payout and rewind the cable. The speed reducer unit includes a first speed reduction stage having an input drive shaft and a torque limiting slip clutch. The input drive shaft is drivingly coupled to the rotary power source and mounted to undergo rotational movement in response to the rotary drive motion provided at the predetermined input speed by the rotary power source. The slip clutch is drivingly coupled to the input drive shaft to undergo rotational movement therewith and operable to receive the rotary drive motion at the input speed from the input drive shaft and to reduce the rotary drive motion to and provide the rotary drive motion as output at a first speed less than the input speed.
The speed reducer unit also includes a second speed reduction stage and a third speed reduction stage. The second speed reduction stage is drivingly coupled to the slip clutch of the first speed reduction stage and operable to receive the rotary drive motion at the first speed from the first speed reduction stage and to reduce the rotary drive motion to and provide the rotary drive motion as output at a second speed less than the first speed. The third speed reduction stage is rotatable to cause the cable supply spool to payout and rewind the cable and is drivingly coupled to the second speed reduction stage to receive the rotary drive motion at the second speed from the second speed reduction stage and to reduce the rotary drive motion to and provide the rotary drive motion at a third speed less than the second speed and thereby rotate the cable supply spool to correspondingly payout and rewind cable at the third speed. The second speed reduction stage also includes means for sensing in which of the cable payout and rewind rotational modes the speed reducer unit is operating at any given time to cause shutoff of operation of the rotary power source in response to sensing the cable payout rotational mode but not the cable rewind rotational mode to thereby enable the slip clutch to function as a slip brake restraining the rotation of the cable supply spool to the speed at which the cable is pulled from the cable supply spool by movement of machinery connected to the cable and to function as a holding brake preventing further rotation of the cable supply spool when movement of the machinery has ceased.
These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and descri
'Hubbell Incorporated
Binda Greg
Browne Lynne H.
Swartz Michael R.
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