GB2294442A - Endless belt drive for a cable - Google Patents

Abstract

A belt drive arrangement for cable reeling purposes comprises first and second rollers 7, 8 around which is disposed a continuous drive belt 10, a plurality of idler rollers 9 disposed in an outwardly curved configuration between the first and second rollers 7, 8, a second belt 19 disposed between respective rollers 15, 16 for causing a cable (not shown) to be pressed into contact with the drive belt 10, and a drive arrangement (not shown) for causing the drive belt 10 to be driven. Intermeshing gears 17, 18 ensure simultaneous drive of the two-belts 10, 19. Pairs of idler rollers 9 in a shallow V-formulation may be provided (fig. 4, not shown). <IMAGE>

Description

Belt Drive Arrangements This invention relates to belt drive arrangements, and is especially applicable to such arrangements for use in cable reeling equipment.

It is commonplace to operate mobile robotic devices via an umbilical cable which may carry electrical signals to and from the device and also electrical, hydraulic or pneumatic power for operating the device. In such applications it is important to ensure that the umbilical cable is continuously fed out or reeled in dependent upon the movement of the robotic device, in order to ensure that no snagging or overtensioning of the cable takes place and also to ensure that excess cable is kept to a minimum. Prior art forms of cable reeling device often require the use of slip rings for guiding the cable to and from a rotating drum.

It is an object of the present invention to provide an improved form of cable belt drive arrangement.

According to the present invention there is provided a belt drive arrangement for a longitudinal object such as a cable, comprising first and second rollers around which is disposed a continuous drive belt, a plurality of idler rollers disposed in an outwardly curved configuration between the first and second rollers and around which said drive belt extends, means for causing said longitudinal object to be pressed into contact with said drive belt, and means for causing said belt to be driven for causing relative movement between said belt drive arrangement and said longitudinal object.

In a preferred arrangement in accordance with the invention, a second continuous belt is provided for causing said longitudinal object to be pressed into contact with said drive belt, with third and fourth rollers around which said second belt is disposed.

Advantageously, it may be arranged that said first and third rollers are disposed adjacent each other and said second and fourth rollers are disposed adjacent each other, the two pairs of rollers being arranged such that said second belt extends around at least some of said plurality of idler rollers.

One of the pairs of rollers may be geared together, and one of the geared rollers may be externally driven.

In one arrangement a pair of spaced rollers may be provided for pressing said second belt into contact with said longitudinal object, each of said pair of spaced rollers conveniently being a "V" shaped roller.

Advantageously, belt tensioning means may be provided associated with said drive belt and/or said second belt.

It may be arranged that all or any of said first, second, third and fourth rollers are crowned rollers.

Preferably, each ol said plurality of idler rollers comprises a pair of rollers disposed end to end in a "V" configuration.

An exemplary embodiment of the invention will now be described, reference being made to the accompanying drawings, in which: Fig. 1 is a sectional plan view of a belt drive arrangement in accordance with the present invention; Fig. 2 is a scrap section side view on the lines BB in Fig. 1; Fig. 3 is a sectional side view on the lines AA in Fig. 1; and Fig. 4 is a sectional side view on the lines CC in Fig. 1.

The belt drive arrangement depicted in the drawings is designed for use with the umbilical cable of a mobile robotic device, but it will be appreciated that it may have much wider application to longitudinal objects other than cable, e.g.

wire, rope and possibly non-circular structures.

The belt drive arrangement shown in the drawing comprises upper and lower rectangular plates 1 and 2 respectively, the periphery of each of which is strengthened by angled sections 3 and 4 respectively which are bolted to them.

The upper and lower plates 1 and 2 are connected together in spaced apart relationship by opposed side plates 5,6 which extend along the major edges of the plates 1 and 2 and are bolted to the respective angled sections 3 and 4 thereof.

Between the plates 1 and 2 there is rotatably mounted a first roller 7 and a second roller 8. Also mounted between the plates 1 and 2 are ten pairs of rotatably mounted idler rollers 9, disposed in outwardly curved configuration between the first roller 7 and the second roller 8. Each of the pairs of rollers 9 has one roller of the pair mounted angularly on the plate 1 and the other mounted angularly on the plate 2, such that the rollers of each pair are disposed end to end in a "V" configuration as is best seen at 9 in Fig. 4.

Around the first and second rollers 7 and 8 and the idler rollers 9 is disposed a continuous belt 10 (Fig. 1), conveniently of leather, plastic, rubber or a suitable composite material.

A belt tensioning arrangement is provided for the belt 10 consisting of a lever 11 pivoted at one end 12 and having a roller 13 mounted on the other end which bears against the belt 10. The lever 11 is provided with a screwed adjustment device 14. By this means, the belt 10 is located in the "V" afforded by the pairs of idler rollers 9.

Also mounted between the plates 1 and 2 is a third roller 15 disposed adjacent the first roller 7, and a fourth roller 16 disposed adjacent the second roller 8. The first and third rollers 7 and 15 respectively are each provided with a gear wheel 17 and 18 respectively which intermesh with one another so that the first and third rollers rotate together but in opposite directions. Around the third and fourth rollers 15 and 16 is disposed a second belt 19 (Fig. 1) which also extends around a guide roller 20.

A belt tensioning arrangement is provided for the belt 19 consisting of a lever 30 pivoted at one end 21 and having a roller 22 mounted on the other end which bears against the belt 19. The lever 30 is provided with a gas spring 23 to provide automatic tensioning of the belt 19.

Because of the relative positioning of the third roller 15 relative to the first roller 7 and the relative positioning of the fourth roller 16 relative to the second roller 8, the belt 19, when a cable is not inserted in the arrangement, is caused to contact the belt 10 over part of the area defined by the inner ones of the pairs of idler rollers 9. In this way a cable, or other longitudinal object, when inserted between the belts 10 and 19 is pressed into contact with the belt 10 and may be driven thereby as will hereinafter be explained.

In order to increase the pressure afforded by the belt 19, a pinch arm assembly 24 is provided comprising a pair of oppositely extending arms 25,26 which extend from the shaft 27 of an operating cylinder 28 and which are provided on their free ends with "V" shaped or waisted rollers 29 which bear against the belt 19 and against any cable which is inserted in the arrangement thereby increasing the friction between the cable and the belt 10.

Drive for the belt drive arrangement thus far described is provided by external means not shown, but may, for example, take the form of a motor drive to one or other of the gear wheels 17,18. Such motor drive may be electrically, hydraulically or pneumatically operated.

The belt drive arrangement which has been described may be used in a cable reeling application in which a cable is inserted between the belts 10 and 19 and the arrangement is driven one way or the other to cause cable to be fed to or withdrawn from a cable reel.

Alternatively, the belt drive arrangement may be used as a remote driver unit in which it is mounted on a cable and is driven so that it can travel along the cable to a remote point where it can be used for monitoring or other purposes.

The belt drive arrangement which has been described works on the capstan principle and, by incorporating the curved surface afforded by the pairs of idler rollers 9, is in effect a section of a large diameter capstan or pulley.

With conventional pulleys, in order for the outer fibres of the cable or umbilical not to be subject to strains which may damage the material, the radius of the pulley should not be less than approximately 5 x the cable or umbilical diameter. Operating as a large capstan the belt drive arrangement which has been described puts the cable around a section of a relatively large radius pulley whilst the unit does not take up the room of the equivalent pulley radius.

From belt drive theory it can be shown that T1/T2 = eke Where T1 = Tension on tight side.

T2 = Tension on slack side.

k = Geometry or system constant.

Ii = Limiting coefficient of friction.

e = Angle of lap.

The belt drive arrangement which has been described has been given by way of example only and may be modified to suit any particular application. For example, the belt 19 has been provided to hold the cable against the main drive belt 10. It is envisaged that in some applications the belt 19 may be dispensed with, but its incorporation has the effect of producing an apparent increase in the coefficient of friction to above unity. This enables the arrangement to drive oily covered or slippery umbilicals or cables.

The arrangement has the ability to be used on a wide range of umbilical or cable diameters without the need for adjustment.

The arrangement imposes a minimum of crushing force on an umbilical or cable relative to the longitudinal tension generated.

The rollers 7, 8, 15 and 16 can be normal cylindrical rollers, however it is preferred to use crowned rollers for maximum load.

The use of the pairs of "V" idler rollers 9 allows the belt 10 to wrap around the cable which improves grip and centralises the cable. An alternative is to use waisted rollers, however the changing diameter would have differing surface velocities resulting in additional wear on the rear of the belt.

In the belt drive arrangement which has been described, a cable is end fed into the arrangement and is inserted between the belts 10 and 19. In some arrangements end feeding of the cable may not be possible in which case it is envisaged that a slot will be provided in the plate 1 which extends from the opposed sides of the arrangement as viewed in Fig. 1, and which follows generally the contour of the belts 10 and 19 around the idler rollers 9, and which enables a cable to be inserted sideways into the drive arrangement. To facilitate this the gas spring 23 and the operating cylinder 28 may be adapted to release the tension on the belt 19 to permit the cable to be inserted between it and belt 10.

Claims (10)

1. A belt drive arrangement for a longitudinal object such as a cable, comprising first and second rollers around which is disposed a continuous drive belt, a plurality of idler rollers disposed in an outwardly curved configuration between the first and second rollers and around which said drive belt extends, means for causing said longitudinal object to be pressed into contact with said drive belt, and means for causing said belt to be driven for causing relative movement between said belt drive arrangement and said longitudinal object.

2. An arrangement as claimed in claim 1, comprising a second continuous belt for causing said longitudinal object to be pressed into contact with said drive belt, and third and fourth rollers around which said second belt is disposed.

3. An arrangement as claimed in claim 2, in which said first and third rollers are disposed adjacent each other and said second and fourth rollers are disposed adjacent each other, the two pairs or rollers being arranged such that said second belt extends around at least some of said plurality of idler rollers.

4. An arrangement as claimed in claim 3, in which one of the pairs of rollers is geared together.

5. An arrangement as claimed in claim 4, in which one of the geared rollers is externally driven.

6. An arrangement as claimed in any of claims 2 to 5, comprising a pair of spaced rollers for pressing said second belt into contact with said longitudinal object.

7. An arrangement as claimed in claim 6, in which each of said pair of spaced rollers is a "V" shaped roller.

8. An arrangement as claimed in any of claims 2 to 7, comprising belt tensioning means associated with said drive belt and/or said second belt.

9. An arrangement as claimed in any of claims 2 to 8, in which all or any of said first, second, third and fourth rollers are crowned rollers.

10. Cable reeling apparatus including a belt drive arrangement as claimed in any preceding claim.

10. An arrangement as claimed in any preceding claim, in which each of said plurality of idler rollers comprises a pair of rollers disposed end to end in a "V" configuration.

11. A belt drive arrangement substantially as hereinbefore described with reference to the accompanying drawings.

12. Cable reeling apparatus including a belt drive arrangement as claimed in any preceding claim.

Amendments to the claims have been filed as follows

1. A belt drive arrangement for a longitudinal object such as a cable, comprising first and second rollers around which is disposed a continuous drive belt, a plurality of idler rollers disposed in an outwardly curved configuration between the first and second rollers and around which said drive belt extends, a second continuous belt for causing said longitudinal object to be pressed into contact with said drive belt, third and fourth rollers around which said second belt is disposed, said first and third rollers being disposed adjacent each other and said second and fourth rollers being disposed adjacent each other, the two pairs or rollers being arranged such that said second belt extends around at least some of said plurality of idler rollers, and means for causing said drive belt to be driven for causing relative movement between said belt drive arrangement and said longitudinal object.

2. An arrangement as claimed in claim 1, in which one of the pairs of rollers is geared together.

3. An arrangement as claimed in claim 2, in which one of the geared rollers is externally driven.

4. An arrangement as claimed in any preceding claim, comprising a pair of spaced rollers for pressing said second belt into contact with said longitudinal object.

5. An arrangement as claimed in claim 4, in which each of said pair of spaced rollers is a "V" shaped roller.

6. An arrangement as claimed in any preceding claim, comprising belt tensioning means associated with said drive belt and/or said second belt.

7. An arrangement as claimed in any preceding claim, in which one or more of said first, second, third and fourth rollers are crowned rollers.

8. An arrangement as claimed in any preceding claim, in which each of said plurality of idler rollers comprises a pair of rollers disposed end to end in a "V" configuration.

9. A belt drive arrangement substantially as hereinbefore described with reference to the accompanying drawings.