WO1994004899A1

WO1994004899A1 - Automatic balancing system

Info

Publication number: WO1994004899A1
Application number: PCT/GB1993/001815
Authority: WO
Inventors: Edward Walter Goody
Original assignee: Euroflex Transmissions Limited
Priority date: 1992-08-25
Filing date: 1993-08-25
Publication date: 1994-03-03
Also published as: AU4970493A; GB9218068D0

Abstract

An automatic balancing device for mounting to a rotatable body to compensate for the presence of an out-of-balance condition during rotation thereof. The balancing device comprises movably mounted weights which by remote control means might be adjusted in response to the detection of an out-of-balance condition in the body during rotation thereby continuously to compensate for the out-of-balance condition as the body rotates.

Description

AUTOMATIC BALANCING SYSTEM

The present invention relates to an automatic balancing system for rotating bodies such as rotating machinery parts.

BACKGROUND OF THE INVENTION

It is of paramount importance to reduce, to the lowest levels possible, vibration in rotating machinery such as high speed turbines, compressors and pump drives caused mainly by the various rotating parts of such machinery being out- of-balance.

Out-of-balance forces in rotating machinery can be caused by a number of factors such as errors in machining and differences in the weight of added components.

At the present time, out-of-balance forces in a particular piece of machinery are reduced to an acceptable level by first mounting the machinery On a sensitive balancing machine which measures magnitude and position of the various applied forces which act on the machinery whilst it is rotating. Material is then either added or removed to compensate for the out-of-balance condition.

This known process is both time consuming and expensive. Moreover for various reasons it is not possible to produce a perfect and repeatable balance since there will always be a residual unbalance when various machinery parts which have been individually balanced are connected together.

The additive effect of these individual residual unbalanced forces may place the complete system outside acceptable operational limits.

As a means of reducing the problem in connecting couplings for example, trim balance holes have been introduced in the flanges of the couplings which allows the trimming, or fine tuning, of balance after assembly. This process is time consuming and expensive as the whole train of machinery has to run up to speed and be monitored for vibration on the shut down and then weights added at the positions indicated by the vibration monitors. The process may have to be repeated several times before satisfactory results are obtained.

Moreover, further complications arise out of the fact that when a train of machinery is in operation, the vibration levels may progressively change and consequent trimming of the balance is required. To enable this to be done, a substantial amount of equipment may require to be removed in order to get at the machinery.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome the problems of the prior art and to provide a device for attachment to a rotatable body such as a rotatable machinery part to enable such to be brought into an acceptably balanced condition by automatically compensating for an out-of-balance condition in the body during rotation and without manual interference with the rotating system.

According to the present invention there is provided an automatic balancing device for mounting to a rotatable body to compensate for the presence of an out-of-balance condition during rotation thereof comprising a support for mounting to the rotatable body, one or more weighting means movably mounted on the support, and remotely controlled operable means for adjusting the position of the or each said weighting means in response to detection of an out-of-balance condition in the body during rotation thereby continuously to compensate for said out-of-balance condition as the body rotates.

Preferably the support is a threaded rod and the or each weighting means an irrotational threaded weight mounted on the rod. said rod being mounted in a housing for rotation about its own axis to move the or each weight to selectable positions along the rod and an axis of rotation corresponding to the axis of rotation of the body to move the or each weight to selectable positions in the plane of rotation of the rod. Advantageously there may be two threaded rods arranged at right angles to one another and in a common rotational plane.

The remotely controlled operable means may be a servo-motor mounted to the housing and actuable in response to the generation of output signals representative of an out-of-balance condition.

Preferably the detection of an out-of-balance condition is effected by vibration monitors which provide said output signals, and means for actuating said servo¬ motor to move the position of the weights in response to said output signals until a balanced condition has been achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention taken with reference to the accompanying drawings wherein;

Fig 1 is a cross-sectional view of an automatic balancing device mounted in a hollow coupling according to one embodiment of the invention;

Figs 2a and 2b of Fig 2 show respectively a cross-sectional view of an automatic balancing device mounted in the hollow shaft of a coupling according to another embodiment of the invention and a cross-section view along the line A- A of Fig 2a;

Fig 3 shows a cross-sectional view of an automatic balancing device mounted in the hollow shaft of a coupling according to another embodiment of the invention;

Fig 4a and 4b of Fig 4 show respectively the cross-sectional view of an automatic balancinii device accordinc to another embodiment of the invention and a cross sectional view along the line A-A thereof; and Fig 5 shows a cross-sectional view of an automatic balancing device according to a still further embodiment of the invention.

PREFERRED EMBODIMENTS OF THE INVENTION

In the following description the same reference numerals will be used to identify identical parts as between the various embodiments of the invention illustrated in the drawings.

The balancing device shown in Fig 1 is mounted inside a tubular centre section 1 of a flexible coupling.

It comprises a fixed housing 2 provided with an annular flange 3 which is fixedly mounted in a corresponding annular recess 4 in an end face of the coupling and held therein by fixings 5 as shown.

The fixed housing 2 has a hub portion 6 which extends within the interior of the tubular section 1.

The other half of the device comprises a housing 7 which rotates around the hub portion 6 on bearings 8. A chamber 9 is formed between the transverse end wall 6' of the hub 6 and the transverse end wall 7' of the rotatable housing 7, the axis of rotation of the housing 7 being on the rotational axis R of the shaft 1.

A threaded rod 10 is mounted in the chamber 9 and is rotatable therein on bearings 11 in a plane at right angles to the axis of rotation R.

A pair of weights 12 are threadedly received on the rod 10, the weights 12 being square in section and prevented from rotation by being in engagement between the facing surfaces of the transverse end walls 6' and 7' of the fixed and rotatable housings 2 and 7 respectively.

The threaded rod 10 is rotatable around its own axis to move the weights 12 by means of a remotely controllable geared motor 13 acting through a pair of bevel gears 14, 15 connected to the motor 13 and threaded rod 10 respectively. Energisation of the motor 13 in response to an out-of-balance condition in whichever rotatable direction of the threaded rod 10 causes one of the weights 12 to move towards the axis R of the coupling and the other away from that axis, thereby doubling the effect of the out-of-balance correction.

A further remotely controllable geared electric motor 16 is located within the fixed housing 2 to rotate the rotatable housing 7 with the rod 10 and on the bearings 8.

Using suitable internal wiring, the electric motors 13, 16 may be energised from an external source, either through contacting brushes or by means of telemetry.

Due to the low current required to operate the motors, the power cells may be in the form of a re-chargeable battery. This could be recharged during normal running of the coupling and operating signals for the motors could then be translated by telemetry.

By using high ratio gearing, the weights 12 can be accurately positioned either angularly or radially to counter any out-of-balance forces in the coupling.

In a long coupling shaft, such as for example a coupling spacer, one balancing device may be mounted at each end to effect two plane balancing.

In the embodiment shown in Fig 2, two threaded rods 10 are arranged at right angles in the rotatable housing 7 to act as an additional counterbalance to an out-of-balance condition in the coupling.

In this embodiment, the rotatable housing 7 rotates on bearings B positioned in the transverse end face 6' of the fixed housing 2, the hub 6 of which is in engagement with the inner surface of the tubular shaft 1.

A servo-motor 17 is mounted for rotation about the axis R and drives one of the threaded rods 10 bv means of the bevel αears 14. 15 as before. A further servo-motor 18 is mounted on the axis R and drives the other threaded rod 10 by means of a bevel gear 19.

The servo-motors 17, 18 operate respectively to adjust the position of the weights 12 on the rods 10, and the position of the rods 10, with the weights, in the rotational plane of the rods 10.

The arrangement shown in Fig 3 is similar to the Fig 1 embodiment in that the weights 12 are moved on the rod 10 via bevel gears 20 and 20' from a high ratio geared motor 21 mounted on the rotational axis R in a casing 22 fastened to the transverse wall 7' of the housing 7.

In this embodiment however, positioning of the weights 12 in the rotatable plane of the rod 10 is achieved in a different way.

This is accomplished by means of a solenoid 23 mounted in the fixed housing 2 and having an energisable central rod 24 carrying a plate 25, the side 26 of which is conical to mate with a corresponding conical surface 27 formed in the transverse wall 6' of the hub 6 of the fixed casing 2. The front face 28 of the plate 25 has pins 29 which engage slots 30 in the casing 7.

The front face 28 of the plate 25 also has a protuberance 31 provided with a conical peripheral surface 32 which matches that on the gear 20'. -An O-ring or similar soft insert is set into the conical surface 32 on the protuberance 31.

In operation, the central rod 24 of the solenoid 23 is held axially away from the motor 21 such that the conical surface 26 on the plate 25 and the matching surface 27 on the fixed housing 2 are in contact.

In this position, the rotatable housing 7 is locked to the fixed housing 2 and any rotation of the motor 21 will move the weights radially 12 by means of the threaded rod 10. When energised, the central rod 24 of the solenoid 23 moves towards the motor 21 releasing the plate 25 such that the protuberance 31 engages the gear 20'. In this position the gear 20' is locked via the plate 25 and locking pins 29 to the rotatable housing 7. Energy supply to the motor 21 will now cause the rotatable housing 7 to revolve around the fixed housing 2 on bearings 8 to displace the weights 10 radially to the desired position. The solenoid 24 will then be de-energised.

The balancing device shown in Fig 4 employs the principle of vectoring balance weights to correct an out-of-balance condition and comprises pair of spaced plates 33 of a support casing (not shown) mounted in fixed diametrical planes in the tubular shaft 1 of a coupling.

A gear ring 34 is arranged between the plates 33, the diameter of the gear ring 34 corresponding to the diameter of the tubular shaft 1.

A geared motor 35 is attached to the side of each plate 33, each motor 35 driving a gear 36 disposed to either side of an inner divider plate 37 loosely located inside the gear ring 34.

Weights in the form of gears 38 are mounted between each motor gear 36 and the peripheral gear ring 34 to either side of the plate 37, such that selective rotation of the motors 35 will move the gear weights 38 angularly and independently to positions such that the combined action of the weights 37 forms a resultant vector opposing the out-of-balance condition in the tubular shaft 1.

The embodiment shown in Fig 5, although similar to that of Fig 4, utilises only one motor. In this embodiment a weight 39 is mounted in two slotted plates 40 and 41 giving the ability when rotated individually to vary the vector sum of the weights 39 and when rotated simultaneously to vary the position of the effective mass of the weights 39.

The plates 40 and 41 are installed in a housing 42 containing a motor 43 and two battery power cells 44 used to power the motor 43. The motor 43 and housing 42 are connected via a motor housing plate 45 to a bearing flange 46. The bearing flange 46 is connected to the housing 42 through a bearing 47 and an annular flange 48.

The rotating plates 40 and 41 which carry the balance weights 39 are held between the annular flange 48, bearing ring 47, and bearing flange 46 as shown.

A rotatable shaft 49 is connected to the output shaft of the motor 43 and runs in bearings 50 and 51 fitted at either end. The inner bearing 51 is located in the bearing flange 46 and the outer bearing 50 is located in the annular flange 48.

The rotating plates 40, 41 are each attached to clutch housings 52 and separated by thrust bearing 53.

The clutch housings 52 are connected to the main shaft 49 using roller or sprag clutches 54.

The clutches 54 permit rotation of the plates 40, 41 in one direction only. Thus by mounting the roller clutches 21 the opposite way round for each of the plates 40, 41 forward rotation of the motor 43 will rotate one plate, say plate 40 forward, leaving the other plate 41 stationary.

Reverse rotation will rotate the other plate, namely plate 41 backwards leaving the previously mentioned plate stationary.

The overall effect is that by a series of forward and reverse motions of the motor 43, the plates 40, 41 and thus the balance weights 39 can be positioned independently to precise required locations.

As an alternative, it would be possible to mount one plate, say plate 40, through its clutch housing 52 directly to the main shaft 49 without the use of the clutch utilising only one clutch connected to the other plate 41. Under these conditions rotating the motor 43 in one direction will move the fixed plate 40 only, the roller clutch 54 permitting the other plate 41 to remain stationary.

For rotating the motor in motor 43 in the other direction, will move both plates 40 and 41 together. In this case the first rotation enables the variation of position of the two balanced weights 39 relative to one another giving a variation in the vector sum of the two weights. The second rotation moving the two plates 40, 41 together thus varies the angular position of the vector sum.

With reference to the Fig 5 embodiment, it should be stated that the use of a single motor with one or two roller clutches may, by various means, be incorporated into any one of the Figs 1 to 4 embodiments described herein.

The power source for the motors in all the embodiments described above may be from an external source or via batteries which may be rechargeable or of long life.

Finally, in the Fig 5 embodiment it would be possible to use, instead of individual balance weights 39, rotating plates with substantial amounts of material removed from one side to give the overall effect of an eccentric mass.

Claims

1. An automatic balancing device for mounting to a rotatable body to compensate for the presence of an out-of-balance condition during rotation thereof comprising a support for mounting to the rotatable body, one or more weighting means movably mounted on the support, and remotely controlled operable means for adjusting the position of the or each said weighting means in response to detection of an out-of-balance condition in the body during rotation thereby continuously to compensate for said out-of-balance condition as the body rotates.

2. An automatic balancing device as claimed in claim 1 wherein the support is a threaded rod and the or each weighting means an irrotational threaded weight mounted on the rod, said rod being mounted in a housing for rotation about its own axis to move the or each weight to selectable positions along the rod and an axis of rotation corresponding to the axis of rotation of the body to move the or each weight to selectable positions in the plane of rotation of the rod.

3. An automatic balancing device as claimed in claim 2 wherein there are two threaded rods arranged at right angles to one another and in a common rotational plane.

4. An automatic balancing device as claimed in claim 1 wherein the support comprises a pair of spaced plates for fixedly mounting to the rotatable body, an annular gear ring mounted between the spaced plates, a freely movable divider plate mounted between the spaced plates, an inner gear wheel arranged on either side of the divider plate, and two driven gear elements forming said weighting means mounted respectively between the annular gear ring and each inner gear wheel.

5. An automatic balancing device as claimed in claim 4 wherein said operable means is in the form of a servo-motor for independent operation of the inner gear wheels to effect selective angular positional movement of the gear driven elements.

6. An automatic balancing device as claimed in claim 1 wherein the weighting means is in the form of balance weights mounted in two independently movable support plates.

7. An automatic balancing device as claimed in claim 6 wherein said operable means is in the form of a servo-motor, and clutch means for enabling the plates to be rotated individually by the servo-motor to vary the vector sum of the balance weights and simultaneously by the servo-motor to vary the position of the effective mass of the balance weights, thereby to compensate for the out-of-balance condition as the body rotates.

8. An automatic balancing device as claimed in any preceding claim wherein the detection of an out-of-balance condition is effected by vibration monitors which provide output signals representative thereof, and means for actuating the servo-motor or motors to move the position of the weights in response to said output signals until a balanced condition has been achieved.