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AU664569B2 - Winch assembly - Google Patents

Winch assembly Download PDF

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Publication number
AU664569B2
AU664569B2 AU28427/92A AU2842792A AU664569B2 AU 664569 B2 AU664569 B2 AU 664569B2 AU 28427/92 A AU28427/92 A AU 28427/92A AU 2842792 A AU2842792 A AU 2842792A AU 664569 B2 AU664569 B2 AU 664569B2
Authority
AU
Australia
Prior art keywords
clutch
tension
cable
motor
rotatably connected
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 - Fee Related
Application number
AU28427/92A
Other versions
AU2842792A (en
Inventor
Donald John Holster
Bruce Incoll
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pace Engineering Pty Ltd
Original Assignee
Pace Engineering Pty Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Pace Engineering Pty Ltd filed Critical Pace Engineering Pty Ltd
Priority to AU28427/92A priority Critical patent/AU664569B2/en
Publication of AU2842792A publication Critical patent/AU2842792A/en
Application granted granted Critical
Publication of AU664569B2 publication Critical patent/AU664569B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Description

pp.- 1 p00011 Regulation 3.2 664
AUSTRALIA
Patents Act, 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Original
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o pico a r ro rrcr~ ~roo o re oa Ir ro oa TO BE COMPLETED BY THE APPLICANT o o r rratl~rr
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~rrr~~ NAME OF APPLICANT: ACTUAL INVENTORS: ADDRESS FOR SERVICE: INVENTION TITLE: DETAILS OF ASSOCIATED PROVISIONAL APPLICATION NO(S): PACE ENGINEERING PTY. LIMITED (ACN 003 725 915) DONALD JOHN HOLSTER and BRUCE
INCOLL
Peter Maxwell Associates Blaxland House, Suite 10, 5 Ross Street, NORTH PARRAMATTA NSW 2151 WINCH ASSEMBLY PK 9514 dated 15th November, 1991 The following statement is a full description of this invention, including the best method of performing it know to me:- -1 1~.
r -T -2- The present invention relates to a winch assembly and particularly to a winch assembly where a cable is wound upon a winch drum to a desired tension.
There are many kinds of winches for a wide variety of tasks. Among the more common kinds of winches used in industry are fixed speed reversing motor winches, hydraulic winches and eddy-current coupling winches, each of which suffer from various disadvantages.
For instance, fixed speed reversing motor winches do not allow quick and sensitive control over the cable winding 0 operation because of the delay in the motor start-up time.
o .o ;Hydraulic winches suffer from the well known operational inefficiency inherent in any hydraulically operated machinery and the requirement to continuously maintain the hoses and other componentry of the sometimes °0 rather complex hydraulic system.
Eddy-current coupling winches are highly inefficient because of their inherent characteristic of constantly operating at 100% inefficiency. Furthermore, the eddy- 20 current coupling that drives such winches has high rotational 0 o S inertia which slows the winch operating response. The eddycurrent coupling componentry of such winches are also Sdifficult to make flameproof and develop a large amount of heat during operation which may make them dangerous to use in coal mines and the like.
It is an object of the present invention to overcome or substantially ameliorate the disadvantages of the prior art.
.r I i -3- According to the invention, there is provided a conveyor belt tension control mechanism comprising: a motor having an output shaft selectively, rotatably connected by first transmission means to a belt tensioner means adapted to increase tension in a conveyor belt by movement of said means in a first direction and reduce tension in said conveyor belt by movement of said means in a second direction; said motor output shaft running continuously in one direction during all operating phases of said conveyor belt tension control mechanism.
Preferably, the first transmission means comprises means for selectively engaging and disengaging said output shaft from said belt tensioner means and means for locking said belt tensioner means at a selected tension position.
In a preferred form of the invention the first transmission means comprises, in series, a first clutch rotatably connected to said output shaft, said first clutch being rotatably connected to a constantly engaged one way clutch, said one way clutch being rotatably connected to a 20 second clutch, said second clutch being rotatably connected to said belt tensioner means.
Preferably, the second transmission means operating mechanically in parallel with said first transmission means, said second transmission means adapted to selectively, rotatably engage said belt tensioner means with said output shaft under overrun conditions of said belt tensioner means whereby said motor acts to limit the movement of said belt ,RA^ tensioner means.
I
1
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i c r
I
I
i rti r '4 -o ~BLU FF g ii ii -4- In a preferred form of the invention the conveyor belt tension control mechanism is effected by winch assembly comprising: a winch drum adapted to reel in cable therearound so that an unwound portion of said cable is at a desired tension, and to pay out said cable when the said unwound portion is above the desired tension, drive means for rotatably urging said drum, said drive means including, in series, a motor rotatably connected by said motor output shaft to a first clutch which is adapted to be engaged for reeling in said cable, said first clutch being rotatably connected to a constantly engaged one-way clutch, said one-way clutch allowing reeling in said cable and being rotatably connected to a second clutch which is adapted to be disengaged for paying out said cable, said second clutch being rotatably connected to said winch drum, tension control means adapted to monitor the tension in S the unwound portion of said cable and, when it monitors a .040 tension below the desired tension, to cause the engagement of o 20 the first clutch so that the drive means rotatably urges said drum for reeling in said cable to the desired tension and, if it monitors a tension above the desired tension, to cause the disengagement of the second clutch for paying out said cable 44 to the desired tension.
In order that the invention may be more readily understood and put into practical effect, reference will be r i. i made to the accompanying drawings wherein:- I Fig. 1 is a schematic representation of a preferred winch assembly according to the invention.
Fig. 2 is a schematic representation of a winch assembly according to a second embodiment of the invention, and oa o 0 Go o 0 0 j 44 i ao o a/ 0 r i, I_ i. .cl -6- Fig. 3 illustrates a preferred manner of usage and behaviour of the winch assembly of Fig. 2 as a conveyor belt tensioning control device.
The winch assembly of Fig. 1 has an electric motor 11 rotatably connected to a first or engaging clutch 12 by a motor driven shaft 13. The engaging clutch 12 is connected to an intermediate shaft 14 which is biased to rotate in a one-way direction by a constantly engaged one-way clutch The intermediate shaft 14 is connected at its end remote from engaging clutch 12 to a second or disengaging clutch 16 such that rotation of the engaging clutch 12 by the motor 11 in the one-way direction determined by the one-way clutch will, through intermediate shaft 14, cause rotation of the disengaging clutch 16. The disengaging clutch 16 is rotatably connected by a gear drive shaft 17 to a gear train 18 which, in turn, is rotatably connected by a winch drum shaft 19 to a winch drum A cable 21 is wound around the drum and has an unwound portion 22 secured to a load (not shown). The tension of the unwound portion 22 is controlled by a tension control means I (not shown).
The motor driven shaft 13 can rotate in one direction only as dictated by the motor 11 and must be in the same direction as that for the intermediate shaft 14 dictated by the one-way clutch In order to reel in cable around the winch drum, the i 1 -7motor 11 is activated, engaging clutch 12 is engaged and the disengaging clutch 16 is engaged.
The motor driven shaft 13, the intermediate shaft 14, the gear drive shaft 17 and the winch drum shaft 19 become rotatably connected so as to cause motor driven reeling in of cable 21. The gear train 18 changes the rotational speed of the combined shafts 13, 14 and 17 dictated by the motor 11 to provide a winch drum rotational speed appropriate to the required reel in speed of the cable.
During this reel in operation, the tension control means continuously monitors the increasing tension in the unwound cable portion 22.
When the tension control means monitors the desired tension, the engaging clutch 12 is disengaged.
The one-way clutch 15 prevents the intermediate shaft 14 and ultimately the winch drum 20 from rotating in the opposite direction, thereby holding the cable wound on the winch drum at the desired tension and restricting the winch drum from paying out cable under the influence of cable tension.
If the tension control means monitors a cable tension *higher than the desired tension, the disengaging clutch 16 is disengaged which allows the cable tension to rotate the winch drum 20 and gear train 18 in a direction opposite to that for reeling in of cable, thereby allowing the winch drum 20 to pay out cable.
During this paying out operation, the tension control
I
-8means continuously monitors the decreasing tension in the unwound cable portion 22.
When the tension control means monitors the desired tension, the disengaging clutch is engaged, and, as mentioned above, the one-way clutch 15 restricts the winch drum 20 from further rotation in the opposite direction, thereby restricting the winch drum 20 from paying out further cable.
Where the engaging clutch 12 is hydraulically, electrically or pneumatically engaged and the disengaging clutch 16 is spring engaged, an advantage of the preferred embodiment of the present invention is that, if there is a power failure during the maintaining of the desired tension, the disengaging clutch 16 remains engaged, thereby not allowing any loss of cable tension, and the engaging clutch 12 becomes disengaged, thereby preventing any inertia stored in the motor 11 from translating through the combined shafts to the winch drum 20 during the power failure.
With reference to Fig. 2 a second embodiment of the invention is shown in schematic form wherein like numbers 20 represent the same components as in respect of the first :1 embodiment illustrated in Fig. 1.
The additional components of the drive train as illustrated in Fig. 2 include an overrun clutch 23 rotatably connected by a first overrun shaft to gear train 18 (which, in turn, remains connected to winch drum shaft 19). The output side of overrun clutch 23 is rotatably connected by second overrun shaft 25 to second gear train 26 which kL -9rotatably connects second overrun shaft 25 to motor shaft drive 13.
The function of overrun clutch 23 is to rotatably engage second overrun shaft 25 to first overrun shaft 24 when first overrun shaft 24 exceeds a predetermined overspeed rotational velocity, thereby directly connecting winch drum shaft 19 to the motor drive shaft 13.
In this embodiment electric motor 11 is a three phase squirrel cage induction motor having a torque speed curve of the type characteristic of such motors as illustrated in the inset in Fig. 2.
As is indicated by the torque speed curve the motor 11 will seek to resist having its motor drive shaft 13 rotate above its synchronous speed with a torque value which varies with the overspeed/slip value relative to synchronous speed/slip. Provided the motor 11 is appropriately rated and geared to cope with the maximum torque which can be exerted upon winch drum 20 then the motor will act to limit the rotational velocity of motor drive shaft 13 to around the 20 synchronous speed of the motor under overrun conditions when overrun clutch 23 is engaged.
The assembly of the second embodiment has particular use as a tension controller for large conveyor belts (refer side section view of conveyor belt in Fig. 3).
As illustrated in Fig. 2 when used for this purpose, cable 22 is connected to tension carriage 27 which rotatably supports conveyor belt idler pulley 28 having a portion of conveyor belt 29 wound therearound.
i The carriage 27 and pulley 28 are of conventional design as known in the art of tensioning arrangements for large cr'veyor belts arranged in the manner illustrated in Fig. 3.
The winch assembly of Fig. 2 is utilised to maintain the tension of conveyor belt 29 within a predetermined range during all operational phases of the belt 29 (eg startup, shutdown, running empty, running full, running intermittently loaded) i. the following manner.
A programmable logic controller (PLC) 30 controls the engagement/disengager 'nt of clutch 12 by means of output A.
It controls the disengagement/engagement of clutch 16 by means of output B. It receives information as to the current tension in belt 29 from analog input C connected to load cell 31.
In use three phase squirrel cage induction motor 11 is connected directly to the mains and left running. If PLC determines that belt 29 is overtensioned as indicated by input C from load cell 31 then a payout phase is commenced simply by disengaging clutch 16 via output B and allowing winch 20 to payout cable 22. The rate of payout is limited to approximately the synchronous speed of the induction motor 11 by the engagement of overrun clutch 23 as previously described.
If PLC 30 senses that conveyor belt 29 is undertensioned as indicated at input C reflecting the value of load cell 31 then a wind in operation is commenced simply by engaging clutch 16 via output B.
c i ;~t -11- In the steady state that is when the load cell indicator set point tension overrun clutch 23 and clutch 12 are disengaged whilst clutch 16 is engaged whereby tension is maintained on cable 22 by the resisting action of one way clutch With reference to the graphs in Fig. 3 it can be seen that the tensioning control system thus effected of conveyor belt 29 is a simple on/off arrangement essentially controlled entirely with reference to the tension of belt 29 as reflected at input C and by the condition of clutch 16 (whether engaged or disengaged as controlled by output B).
Whilst the control arrangement is simple and has a short time constant (of the order of 0.2-0.5 seconds is achievable with conventional programmable controllers and 15 clutch components) it can achieve close control of the tension in belt 29 under all expected operational conditiu' Graph 1 in Fig. 3 illustrates the actual tension condition in conveyor belt 29 as it accelerates from rest up to operational speed with the conveyor belt tensioning 20 arrangement illustrated in Fig. 2 operational. It can be seen that the conveyor belt tension value oscillates within a close band about a value of 25 kN.
Graph 2 in Fig. 3 shows the actions of the winch assembly of Fig. 2 to achieve that control, namely relatively short wind on periods to counteract the lowering of tension in the conveyor belt on the feed out side of conveyor drive pulley 32 during acceleration from rest followed by short bursts of payout (when induction motor 11 goes into a
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-12regenerate mode as and when overrun clutch 23 engages) so as to limit overshoot of tension as the conveyor belt 29 comes up to operational speed.
Typical cor-'"onents to achieve the 25 kN tension level in belt 29 would include the following: motor 11: squirrel cage induction motor 30 kW engaging clutch 12: normally disengaged 0.2 second pull in and disengagement time.
disengaging clutch 16: normally engaged 0.2 second pull in and disengagement time overrun clutch 23: normally disengaged engagement/disengagement time- 0.2 seconds PLC 30: manufacturer Siemens maximum response time seconds.
Accordingly it can be seen that the electrical and mechanical efficiency of the winch assembly 10 is relatively high thereby ensuring relatively little heat dissipation whilst the time constant of the resulting system is more than adequate to control the tension within a large conveyor belt 20 29 to within relatively close tolerances.
"ft The winch assembly 10 of the second embodiment may be retro-fitted to existing tension carriages 27 to replace j longer time constant/less adequate control mechanisms.
Various modifications may be made in details of design and construction without departing from the scope or ambit of the invention.
L I-

Claims (13)

1. A conveyor belt tension control mechanism comprising a motor having an output shaft selectively, rotatably connected by first transmission means to a belt tensioner means adapted to increase tension in a conveyor belt by movement of said means in a first direction and reduce tension in said conveyor belt by movement of said means in a second direction; said motor output shaft running continuously in one direction during all operating phases of said conveyor belt tension control mechanism.
2. The mechanism of claim 1 wherein said first transmission means comprises means for selectively engaging and disengaging said output shaft from said belt tensioner means and means for locking said belt tensioner means at a selected tension position.
3. The mechanism of claim 2 wherein said first S*4' t, transmission means comprises, in series, a first clutch 'rotatably connected to said output shaft, said first clutch So:o, being rotatably connected to a constantly engaged one way 0 8 clutch, said one way clutch being rotatably connected to a second clutch, said second clutch being rotatably connected 0 0 to said belt tensioner means. oia
4. The mechanism of claim 3 wherein said first clutch is iS 'normally disengaged, said second clutch is normally engaged and said one way clutch comprises said means for locking said belt tensioner means.
5. The mechanism of claim 1 further including second 0 i -14- transmission means operating mechanically in parallel with said first transmission means, said second transmission means adapted to selectively, rotatably engage said belt tensioner means with said output shaft under overrun conditions of said belt tensioner means whereby said motor acts to limit the movement of said belt tensioner means.
6. A conveyor belt tension control mechanism as claimed in claim 1 effected by a winch assembly comprising: a winch drum adapted to reel in cable therearound so that an unwound portion of said cable is at a desired tension, and to pay out said cable when the said unwound portion is above the desired tension, drive means for rotatably urging said drum, said drive means including, in series, a motor rotatably connected by said motor output shaft to a first clutch which is adapted to be engaged for reeling in said cable, said first clutch being rotatably connected to a con.3tantly engaged one-way clutch, said one-way clutch allowing reeling in said cable and being rotatably connected to a second clutch which is adapted to be disengaged for paying out said cable, said second clutch being rotatably connected to said winch drum, S. 1 tension control means adapted to monitor the tension in Sa the unwound portion of said cable and, when it monitors a tension below the desired tension, to cause the engagement of the first clutch so that the drive means rotatably urges said drum for reeling in said cable to the desired tension and, if it monitors a tension above the desired tension, to cause the c~ D, o 0 0 0 0 0 0 0 0 0000 0000 0 00 0 00 e 0 0 o o 00 0 e 0 00 0 0 05 0 S 0 0 a 0 6 0 Q a o QS o a disengagement of the second clutch for paying out said cable to the desired tension.
7. The tension control mechanism of claim 6 wherein the first clutch is hydraulically, electrically or pneumatically engaged and is disengaged by a spring release mechanism.
8. The tension control mechanism of claim 7 wherein the constantly engaged one-way clutch is self actuating and comprises either a sprag type clutch, a ramp and roller type clutch or a cam clutch.
9. The tension control mechanism of claim 8 wherein the second clutch is engaged by a spring engaging mechanism and is hydraulically, electrically or pneumatically disengaged. The tension control mechanism of claim 6 wherein the tension control means monitors the tension in the unwound portion of the cable either directly or indirectly.
11. The tension control mechanism of claim 10 wherein the tension control means comprises an electronically operated controller that includes an electronic sensor for monitoring cable tension, a programmabJe data reference bank for comparing the monitored tension with the desired tension, and electronically driven actuators for causing the engagement and disengagement of both the first and second clutches at the appropriate periods in the winching operation.
12. The tension control mechanism of claim 6 further including an overrun clutch rotatably connecting said drum to said motor prior to said first clutch whereby the overrun speed of said drum when said second clutch is disengaged is t) -16- Slimited by the torque/speed characteristic of said motor. i 13. The tension control mechanism of claim 12 wherein said motor is a squirrel cage induction motor.
14. A conveyor belt tension control mechanism as hereinbefore particularly described with reference to what is shown in the accompanying drawings. Dated this 25th day of September, 1995. PACE ENGINEERING PTY. LIMITED By their Patent Attorneys PETER MAXWELL ASSOCIATES 6o 00 0 1 I r ABSTRACT A winch assembly 10 includes a first transmission assembly rotatably connecting a motor 11 to a winch drum comprising clutches 12, 16 adapted to rotatably engage an output shaft 13 of the motor 11 to a winch drum shaft 19 of the winch drum 20 to wind in cable 22 onto the winch drum and to payout cable 22 from the winch drum 20 by disengagement of motor drive shaft 13 from winch drum shaft
19. SThe winch assembly 10 further includes a second transmission assembly comprising an overrun clutch 23 rotatably connecting winch drum shaft 19 to motor drive shaft 13 if and when the payout speed of cable 22 from drum exceeds a predetermined value. The winch assembly 10 is particularly suited to control conveyor belt tension in relatively large conveyor belts by simple on/off control of the clutches 12, 16 in response to sensed conveyor belt tension. I S t A -t
AU28427/92A 1991-11-15 1992-11-16 Winch assembly Expired - Fee Related AU664569B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU28427/92A AU664569B2 (en) 1991-11-15 1992-11-16 Winch assembly

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPK9514 1991-11-15
AUPK951491 1991-11-15
AU28427/92A AU664569B2 (en) 1991-11-15 1992-11-16 Winch assembly

Publications (2)

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AU2842792A AU2842792A (en) 1993-05-20
AU664569B2 true AU664569B2 (en) 1995-11-23

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AU28427/92A Expired - Fee Related AU664569B2 (en) 1991-11-15 1992-11-16 Winch assembly

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU4573679A (en) * 1978-04-04 1979-10-11 Vickers Shipbuilding Group Limited Winch mechanisms
AU525041B2 (en) * 1978-07-21 1982-10-14 Aquila Steel Company Limited Cranes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU4573679A (en) * 1978-04-04 1979-10-11 Vickers Shipbuilding Group Limited Winch mechanisms
AU525041B2 (en) * 1978-07-21 1982-10-14 Aquila Steel Company Limited Cranes

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