GB2342412A - Torque limitation device - Google Patents
Torque limitation device Download PDFInfo
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- GB2342412A GB2342412A GB9818480A GB9818480A GB2342412A GB 2342412 A GB2342412 A GB 2342412A GB 9818480 A GB9818480 A GB 9818480A GB 9818480 A GB9818480 A GB 9818480A GB 2342412 A GB2342412 A GB 2342412A
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- driven
- torque limitation
- limitation device
- driving
- plate
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D7/00—Slip couplings, e.g. slipping on overload, for absorbing shock
- F16D7/002—Slip couplings, e.g. slipping on overload, for absorbing shock the torque being transmitted and limited by yielding of an elastomeric race
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Rollers For Roller Conveyors For Transfer (AREA)
Abstract
A torque transmitting device, eg. for a roller conveyor 10, comprises: a driving member, eg. a chain sprocket 14, having a driving surface 14.1; a driven member, eg. a reaction plate 25 fixed to a roller shaft 11 via hub 15, having a driven surface; resilient force transmitting means, eg. elastomeric balls 24, disposed in a cage/carrier 22 and in frictional contact with the driving and driven surfaces; and adjustment means 26 for adjusting to a pre-determined amount the compression of said resilient means, and hence the frictional torque capability of the device, eg. by reducing the distance between the driving and driven surfaces. The adjustment means may comprise a plate having arcuate ramps (25.2, Fig.6C) on one side thereof, which co-operate with ramps (26.2, Fig.7C) on the opposing face of a reaction plate, whereby relative movement therebetween moves the two plates apart, thereby urging the reaction plate against the resilient means. The device may also be used in an assembly in which the roller has a static axle (Fig.9).
Description
2342412 1_ TORQUE LIMITATION DEVICE This invention relates to a torque
limitation device or clutch, in particular though not exclusively a torque limitation device that is suitable for use with a conveyor. The invention also relates to conveyors, especially roller conveyors, including the toru limitation device.
In using mechanical conveyors there is a need for separate, spaced articles on the conveyor to be allowed to accumulate in line in a predetermined zone, for example for subsequent division of the line or for other processing. Although the line of articles can readily be brought to a halt by the use, for example, of a'mechanical stop, it is important to preclude the conveyor rollers from continuing to rotate relative to the bottoms of the stationary articles. Stopping the rollers by is cutting the power to the conveyor is not a practicable course of action, largely because the conveyor needs to be kept moving so as to drive rollers (usually by chain and sprocket means) in other parts of the line.
Our British Patent No. 2 290 358 discloses a torque limitation device, suitable for use with a conveyor, comprising a driving member, e.g. a chain sprocket having a driving surface; a driven member, e.g. a reaction plate fixed to a roller shaft, having a driven surface; and disposed between and in frictional contact with said driving and driven surfaces, a resilient force- transmitting means, e.g. elastomeric balls in apertures in a cage.
This torque limitation device has proved most successful in practical use. In particular, the torque limits it provides are adjustable within wide limits, and the device is thereby effective for conveyed articles of very different weights. In that torque limitation device the torque limits are normally adjusted by selecting a predetermined number of the resilient elements to be present in the cage.
The present invention now provides an improved torque limitation device which, while being adjustable so as to effect a wide selection of torque limits, does not require the device to be dismantled in order to change from one torque limit to another. 15 Accordingly, in a first aspect the present invention provides a torque limitation device which comprises:
a driving member having a driving surface; a driven member having a driven surface, said driving surface and said driven surface being so disposed as to define a gap between them; and, disposed in said gap and in frictional contact with the driving surface and the driven surface, a resilient force-transmitting means capable in a first mode of transmitting force from said driving member to said driven member and, in a second mode, of 10 ceasing to transmit the force and to rotate while in contact with said driving surface and said driven surface; -3 characterised in that said device includes adjustment means for mechanically adjusting the amount of compression applied to said resilient elements when they are in said frictional contact with said driving surface and said driven surface.
In a second aspect the invention provides a roller conveyor in which one or more of the rollers are provided with a torque limitation device according to the first aspect of the invention.
In a third aspect the invention provides an adjustment means for use with, or as part of, the torque limitation device of the invention.
The invention is concerned, in particular, with a torque limitation device for roller conveyors driven by chain and sprocket wheel means, and it is with particular reference to such conveyors that the following description relates.
In a preferred form of the invention the f orce- transmitting member comprises one or more resilient rotatable elements accommodated in a cage or other carrier, the carrier being disposed between the driving and the driven surfaces for rotation about an axis of the carrier. As the rotatable elements there can be used, for example, balls (which can be, for example, of spherical or spheroidal shape) or rollers (for example of cylindrical or frusto-conical shape). Any convenient number of rotatable elements can be used, for example any number in the range 3 to 10 (f or example 5, 6, 7 or 8), the number depending to some extent on the size of the carrier and on the torque limit required for the device. In general, the torque limit is greater the greater the number of balls or other rotatable elements.
In order to provide for flexibility in use, it is convenient to use a carrier having apertures to accommodate the rotatable elements in a number greater than the minimum number required.
For example, the carrier can comprise a rotatable disc having formed therein, for example, 6 to 10 apertures in which are disposed, normally equi-angularly, the balls or other rotatable elements, which can be, for example, 3 to 10, for instance 5,6 7 or 8, in number. If desired every one of the apertures can contain a rotatable element.
The rotatable elements are preferably disposed equiangularly with respect to each other; they are conveniently disposed at a common radial distance from the axis of rotation of the carrier.
The rotatable elements normally are ones having a substantial degree of resilience. The resilience of the ball or other rotatable member is preferably such that it is in a compressed, distorted state in its location between the driving surface and the driven surface. Thus, where the rotatable elements are spherical balls in their normal, relaxed state, they will assume a spheroidal shape when in a compressed state between the driving and driven surfaces.
The ball or other rotatable element is conveniently of a polyurethane elastomer having an appropriate resilience.
Suitable materials are polyurethane elastomers having a Shore A hardness in the range from 80 to 100, for example in the range from 90 to 98.
A preferred form of carrier is a cylindrical plate having formed therein a plurality of apertures each to accommodate an element rotatable within its respective aperture or recess. The apertures are preferably disposed equi-angularly in the plate and preferably disposed at a common radial distance from the axis of rotation of the plate.
The driven surface can be one having formed therein a plurality of recesses each sequentially to receive the rotatable elements as they move relative to the driven surface.
In normal operation the balls or other resilient members have two modes of operation. In the first, torque- transmitting, -6mode the resilient members are in a compressed state between the driving and driven members and do not move with respect to either. In the second mode the resilient members, still in a compressed state, roll gainst an adjacent surface of the driving and/or driven member. This rolling motion is normally without slipage.
Reference is now made to the adjustment means of the torque limitation device of the invention.
In one form the adjustment means comprises means to mechanically adjust, by incremental amounts, the width of the gap between the driving surface of the driving member and the driven surface of the driven member, and thereby adjust the degree of compression of said resilient elements.
In another form, for example in combination with said first form, the adjustment means comprises a first member for transmitting a lateral force to the driven member so as to urge it against the resilient elements in the cage, a second member adapted for rotational movement co-axial with that of the driven member, and means operatively connecting said first and second members whereby said rotational movement of the second member results in lateral force being applied to the first member. In one embodiment of said another form said first member is carried by, or is comprised by, the reaction plate and said second member is a plate mounted co-axially with the reaction plate. The means operatively connecting the first and second members is conveniently a ramp device comprising co-operating ramps disposed for relative motion while in face-to-face contact.
In a preferred embodiment the adjustment means includes an adjustment plate mounted co-axially and substantially parallel to the reaction plate for relative rotational movement and relative axial movement. The opposed faces of the reaction plate and the adjustment plate each carries co-operating arcuate ramps disposed for face-to-face sliding contact, whereby relative movement between them results in the reaction plate and adjustment plate being moved apart, thereby urging the reaction plate against the resilient balls or other resilient elements.
The present invention provides torque limitation devices suitable for use with conveyors having rotatable axles and torque limitation devices suitable for use with conveyors having static axles. Normally, in a rotatable axle conveyor the axles rotate in the conveyor frame and the rollers are f ixed on the axles, whereas in a static axle conveyor the axles are fixed in the conveyor frame and roller rotate on the axles. Normally, in chain and sprocket conveyors, if the torque limitation device is for the use with a rotatable axle conveyor the device is mounted outboard of the chain-driven sprocket; if it is for use with a static axle conveyor it is normally mounted inboard of the chain driven sprocket.
A further advantage provided by the present invention is in starting up the conveyor, in which circumstance the torque limitation device acts as a clutch and smooths the transmission of power from the driven sprocket wheel to the driven member.
The balls or other rotatable elements can be of any suitable material that provides a suitable resilience and/or coefficient of friction. Suitable materials, mentioned by way of example, are thermoplastic polyurethane elastomers, for instance those sold by BASF under the trade mark 11Elastollanll, especially those of the C series based on polyester, for example C90A and C74D.
Physical properties of members of the Elastollan C series are as is follows:
Units DIN C78A C80A C85A C90A C59D C60D C64D C74:b Hardness shore A 53505 80 82 87 93 "S Hardness shore D 3 53505 36 41 57 60 63 j Density 1 ctr, 2 53479 1.18 1.19 1.19 1.20 1.23 1.23 1.24 1.25 Tensile strenth NIMM 53504 45 45 so so 55 55 55 55 1 0, Elongation at break m 2 53504 600 600 600 550 400 400 400 350 20% Tensile modulus N / miri 2 53504 2 2.5 3 7 12 16 17 28 100' Tensile modulus N /rnm 53504 j.5 4.5 5.5 9 17 20 24 30 0 1 2 35)s 35 300% Tensile modulus N lmm 53504 7.5 8.5 9.5 15 30 Modulus of elasticity tensile test (lest 2 specimen 3mm) NIMM 53457 250 330 390 730 Tear strength N/om 53515 60 65 75 100 170 190 210 250 3 5 Abrasion loss mm 53516 30 30 30 30 35 35 1 3 Compression set at)s 1 40 40 40 room temperature.1 53517 25 25 25 30 Compression set at 700C % 53517 35 35 35 40 so 50 55 60.
Tensile strength alfter storace in water at B011C 2 48 48 50 for 21 days NIMM 53504 35 38 40 48 Elongatio at break -orage in water after st. r3504 650 150 480 450 420 3,80 at 800C for 21 davs 01. - 650 650 1 measured with test spezimen S2 with a strain rate of 100 mmimin.
ThE test samples were punched out of 2mrr. or 6mm injection.4noulded sheets and tempered at loo,c for 20 hours The driven surface can, if desired, have formed therein a plurality of recesses to provide an increase in torque. Thus, for example, these recesses can be recesses bounded by a spherical or conical surf ace or can be in the f orm of grooves radially disposed in the driven surf ace. The balls or other rotatable elements, when in engagement with the respective recesses, can be either in a relaxed, uncompressed state or in a distorted, compressed state. In either event, when the balls move from a first recess to the next adjacent recess they assume a distorted, compressed state between the first recess and said adjacent recess. In one f orm, given by way of example, the recesses can be shallow conical recesses disposed equi-angularly and at a common radial distance f rom the centre of a driven plate.
The number and disposition of the recesses is preferably such that there is some misalignment of the recesses with the resilient balls so as to avoid all of the balls being located in recesses at the same time and all moving out of the recesses at the same time. This latter arrangement, though included in the invention is not preferred because it results in sudden changes in the torque transmitted by the resilient balls. Instead, it is preferred that balls move into, and out of, the recesses in a consecutive manner. For example, where the balls are disposed equi-angularly in their carrier and the recesses are disposed equiangularly in the driven surface, the number of balls is unequal to the number of recesses (either greater than or less than), thereby providing that some but not all of the balls are located in recesses at any one time.
There are now described, by way of example and with reference to the accompanying drawings, preferred embodiments of torque limitation devices of the present invention and of conveyors equipped with the devices. FIG. 1 to FIG. 8C relate to a conveyor having rotatable axles and FIG. 9 and FIG. 10 relate to a conveyor having static axles.
In the drawings:
FIG. I is a median cross-section of an accumulator roller assembly including a torque limitation device of the present invention; FIG. 2 is an enlargement of the torque limitation device portion of the roller assembly of FIG. 1; FIG. 3 is an enlargement of a portion of FIG. 2 showing, in greater detail, a hub and a bush, both components of the torque limitation device; FIG. 4A is an elevation of the hub shown in FIG. 3; FIG. 4B and FIG. 4C are opposed end views of the hub of FIG. 4A; FIG. 4D is a median cross-section of the hub of FIG. 4A; FIG. 5A and FIG. 5B are opposed end views of the bush -12 shown in FIG. 3; FIG. SC is a cross-section on the line A-A of FIG. 5A; FIG. 6A and FIG, 6B are opposed face views of a pressure plate of a pressure adjustment device; FIG. 6C is a cross-section on the line A-A of FIG. 6B; FIG. 7A and FIG. 7B are opposed f ace views of an adjustment ring of the pressure adjustment device; FIG. 7C is a side elevation of the adjustment ring of FIG. 7A and 7B; FIG. 7D is a cross-section on the line A-A of FIG. 7A; FIG. 8A and FIG. 8B are opposed face views of an index disc of the pressure adjustment device; FIG. 8C is a cross-section on the line A-A of FIG. 8A; FIG. 9 shows in its lower portion an elevation and in its upper portion a section of an accumulator roller assembly including a torque limitation device of the present invention, the roller assembly having a static axle; and -13FIG. 10 is an enlargement of the torque limitation device portion of the roller assembly of FIG. 9.
The conveyor includes a plurality of parallel cylindrical rollers (10), respective rollers being fixedly secured to hexagonal axles (11) whose end portions are journalled in bearings (12). The conveyor is driven by a motor (not shown) through a drive sprocket wheel (not shown) and a chain (13) which engages sprocket wheels (14), one of which is shown in FIGS. 1, 2 and 3. The sprockets (14) have formed therein hexagonal bores and are a sliding fit on the respective axles (11).
The mechanism is enclosed in housing (29) having secured thereto a polyethylene wear strip guard (13.1).
With particular reference to FIGS. 1 and 2, the end portion of axle (11) carries, as a sliding f it, a hub (15) comprising an annular portion (15.1) having a bore of hexagonal cross-section and a periphery of circular cross-section, and a flange portion (15.2) Thus, the hub (15) can be regarded, in practice as part of the axle. The hub is held in position on the axle by means of a washer (16) and a retaining bolt (17) engaging a screw threaded recess (18), and at the other end by a spacer (19) which spaces it apart from bearing (12). An annular bush (20) on which sprocket (14) can rotate, is carried on the hub.
As shown in particular in Figures 4A to 4D, the annular portion (15.1) of the hub (15) has formed therein three like, -14parallel, longitudinally extending, grooves (15.3) spaced apart from each other by 1200, the purpose of which is described below. The hub annular portion also has a circumferential groove (15.4) to accommodate circlet clip (21), the purpose of which is described below.
On the annular portion of hub (15) and adjacent to sprocket (14) is mounted an annular cage (22); the latter contains, in a plurality of spaced apertures (23), a plurality of resilient balls (24). In the embodiment illustrated in the drawings the cage is in the form of a circular, annular disc rotatably mounted on hub (15) and having a plurality of circular apertures (23) disposed equi-angularly and at a common radial distance from the centre of the disc, each aperture containing a like torquetransmitting polyurethane rubber ball (24) of high resilience. The balls have a common diameter which is greater than the thickness of disc and thus the balls protrude from each face of the disc.
An annular reaction (pressure) plate (25) is fixedly mounted on hub (15). The cage (22) is disposed between the reaction plate (25) and sprocket (14) so that the resilient balls are in contact both with driving surface (14. 1) of the sprocket and with the driven surface (25.1) of the reaction plate.
The reaction plate (25) (shown in greater details in FIGS. 6A, 6B and 6C), has an inner periphery of circular cross-section to e ngage the annular portion of hub (15). However, it is -is- prevented from relative rotation on hub (15) by means of like equi- angularly spaced lugs (25.1) which engage respectively the parallel grooves (15.3) in hub (15). As shown in FIGS. 6A to 6C, the reaction plate is of a generally annular shape. One face (FIG. 6A) is substantially planar; the other face (FIG. 6B) has three, like, inclined portions or ramps (25.2) each of arcuate shape and rising in an anti-clockwise direction from the 11 - 91 sign to the 11 + "sign. The ramps can be contiguous, the upper end of one ramp being adjacent the lower end of the next adjacent ramp. The angle of inclination of the ramps is, for example, a uniform angle, for example in the range 0.50 to 50, for instance in the range 20 to 40. In the embodiment shown in the drawings the angle of the ramps was a uniform angle of 2.20.
Adjacent the upper end of each ramp is a stop (25.3). Each ramp is preferably accompanied by a scale of values, for example 0 to 9 as shown in FIG. 6B, to facilitate pre-determined setting of the device.
FIGS. 7A, 7B, 7C and 7D show an adjustment ring (26) disposed adjacent, and in contact with, the reaction plate (25) but, unlike the latter, mounted for rotation on hub (15).
Adjustment ring (26) is an annular plate, conveniently of the same or similar dimensions to the reaction plate (25). On a first face (FIG. 7A) it includes inclined portions or ramps (26.2) for co-operation with the ramps (25.2) of the reaction plate, and stops (26.5). The shape and dimensions of the ramps of the adjustment ring and/or stops (26.5) are conveniently the same as, or similar to, those of the reaction plate. On its -16 other (second) face (FIG. 7B) the adjustment ring (26) has calibration means, for example, a plurality of like protrusions (26.3), depressions or other engagement means for co-operation with means carried by the index disc described below.
The adjustment ring preferably has slots (26.4) or equivalent by means of which the ring can be engaged by a spanner or other tool to adjust the angular position of the ring with respect to the reaction plate (25). The slots or other means can be conveniently disposed equi-angularly of each other in the periphery of the adjustment plate. Said means can be so dimensioned and positioned as to provide an observation aperture to observe respective aligned index numbers of the reaction plate.
FIGS. 8A, 8B and 8C illustrate an index means which is, in this embodiment, a disc (27) fixedly mounted on hub (15), being prevented from rotation thereon by means of lugs (27.1) which engage, respectively, the parallel grooves (15.3) in the hub. The index disc has means for said co-operation with the calibration means of the adjustment plate, for example a plurality of depressions (27.2) (or protrusions) to engage a plurality of protrusions (26.3) (or depressions) of the adjustment plate.
The index plate is captured on the axle (11) by means of circlet clip (21) which engages circumferential groove (15.4) of hub (15).
In the embodiment illustrated in the drawings the diameter of index disc (27) is sufficiently smaller than that of adjustment plate that it does not obscure the respective index numbers of pressure plate (25) that are visible in windows (26.4) of the adjustment ring.
The balls used in the preferred embodiment described above were of a polyurethane elastomer having the following a Shore A Hardness of 98.
MODE OF OPERATION OF THE FIRST EMBODIMENT is A general mode or method of operation of the torque limiting device described above with reference to FIGS. 1 to 8C of the accompanying drawings can, for example, be as follows:
When the conveyor is in its normal operating mode, that is, being driven by the motor through the drive sprocket wheel, chain (13) and driven sprocket wheel (14), torque is transmitted from the sprocket wheel (14) through the balls (24) to the reaction plate (25), which causes the axle (11) and roller (10) to rotate at the same angular velocity as the sprocket wheel, the balls (24), in a compressed state, being stationary with respect to the driving surface (14. 1) of sprocket wheel (14) and the driven surface (25.1) of reaction plate (25). In this mode a line of articles carried by the conveyor moves forward at a constant -18 linear velocity. If that flow of articles is interrupted,for example by means of a mechanical stop, the articles accumulate on the conveyor and a torque is set up in the rollers supporting the articles, this torque being transmitted through axle (11) to reaction plate (25) When the torque limit of the torque limitation device is reached the balls begin to rotate while remaining compressed and in contact both with the driving surface (14.1) and with the driven surface (25.1); and the drive between sprocket wheel (14), and reaction plate (25) is thereby disengaged allowing the rollers (10) supporting the articles to come to rest.
When the mechanical stop or other braking means is removed frictional force between the balls (24) and the driving and driven surfaces is re-established, the balls come to rest between the surfaces and transmission of power from the sprocket wheels (14) to reaction plate (25) is resumed.
A cylindrical oil shield (28), secured to sprocket (14) by welding, is disposed coaxially with respect to the cage (22) to prevent accidental ingress of oil.
The dimensions and disposition of the various component parts are such that, in use, the balls are held in compression between sprocket and reaction member. The degree of compression is such that the diameter of the balls is, for example, about one and a half mm. less in the fully compressed state than in their uncompressed state.
The balls used in the embodiment described above were spherical balls and composed of Elastollan C90A (or alternatively Elastollan C74D).
The size and number of balls used in the device described above with reference to the drawings were as follows:
Number of balls 10 Diameter of balls 8 mm As stated above, the degree of compression of the balls can be one and a half mm. The term "degree of compression,' in this context indicates the difference between the diameter of the balls in their uncompressed state and the distance between the driving surface (for example the sprockets shown in the drawings) and the driven surface (for example the reaction plates shown in the drawings). Degrees of compression other than one and a half mm can, if desired be used; the greater the degree of compression the greater is the torque limit that can be obtained. Suitable alternative degrees of compression are in the range 0.5mm to 4mm, for example, 1, 2 or 2.5mm.
The degree of compression can be adjusted, for example, by choosing balls or other resilient rotatable elements of a particular size; an increase in the diameter of resilient balls, for instance, results in a greater degree of compression and, in consequence, an increase in the torque limit of the device.
-20 The adjustment means feature of the torque limitation device can be used as follows. By way of example, it is assumed that the lowest value of torque limit is required. Accordingly, the adjustment ring (26) is turned, as necessary, by means of a spanner (or other suitable tool) so that the index digit 11011 of the pressure plate/reaction plate (25) appears in each of the slots/windows (26.4) thereby indicating that the co-operating ramps (25.2) of the reaction plate (25) and the (26.2) of the adjustment ring overlap to a minimum extent (if any). In this position the face (25.1) of pressure plate (25) in contact with balls (24) exerts a minimum pressure on them. Thus, a low torque limit of the torque limitation device is effected. The adjustment ring (26) is held in position with respect to reaction plate (25) by the engagement of the protrusion calibration means (26.3) of the adjustment ring with the depression calibration means (27.2) of the index disc (27).
If, by way of example, it is then wished to use the highest value of torque limit, the adjustment ring (26) is turned until the index digit 1191' of reaction plate (25) appears in each of the slot/windows (26,4), thereby indicating that the co-operating ramps (25.2) of reaction plate and (26.2) of the adjustment ring overlap, in face-to-face contact, to a maximum, or substantially maximum, extent. In that position the reaction plate is displaced in a lateral direction from adjustment ring, exerts a substantially maximum pressure on balls (24) and thereby compresses them to a substantial extent. Thus, a high torque limit of the torque limitation device is effected. As before, -21 the adjustment ring (26) is held in position with respect to reaction plate (25) by the engagement, in a new position, of the protrusion calibration means (26.3) of the adjustment ring with the depression calibration means (27.2) of the index disc (27).
A second embodiment of the invention, given by way of example, is now described with reference to FIGS. 9 and 10. In this embodiment the axles of the conveyor are static, that is static with respect to the conveyor frame, and each carries a roller rotatably mounted thereon. Thus, the conveyor includes a plurality of parallel cylindrical rollers (110) each mounted, by means of bearings (110.1), on a static axle (111) held in the conveyor frame and driven by a motor through a drive sprocket wheel (not shown) and a chain (not shown) which engages sprocket wheels one of which (112) is shown in FIGS. 9 and 10.
The roller comprises a hollow cylindrical member (110.2) secured by crimping to an end piece (110.3). The end piece (110.3) comprises a cylindrical portion (110.4) and a flange portion (110.5). The outer surface of the end piece has secured thereto an annular wear plate (110.6 which provides a driven surface of the torque limitation device. In the angle of the end piece there is secured by welding an annular spacer (110. 8) whose purpose is to hold the bearing (110.1) apart from the flange (110.5).
Axle (111) has secured to it first and second stops (111.1 and 111.2).In between the first stop (111.1) and adjacent -22 bearing the axle carries a compression spring (111.3) against which the axle can be moved axially and thereby compress the spring in locating the axle in the conveyor frame.
Axle (111) carries a hub (113) which has a hexagonal bore, by means of which it is a sliding fit on the axle and has cylindrical periphery. The hub is held in position on the axle by said second stop (111.2) at one end and by the conveyor frame (not shown) at the other end. Sprocket (112) is mounted on the hub by means of bearing (114) which is prevented from outward movement by circlip (115) located in a circumferential groove inthe hub. Sprocket bearing (114) is protected from the ingress of dust or other contamination by annular dust cap (114.1) whose annulus is a push fit on the end of hub (113). Sprocket (112) includes an inwardly directed annular flange or extension portion (116) carrying three equally-angularly spaced lugs one of which (117) is shown in FIGS. 9 and 10.
On the hub (113) is rotatably mounted a carrier or cage (118) in the form of a circular plate and having a plurality of spaced apertures containing a plurality of resilient balls (119).
The carrier and/or balls can be, for example, similar to those described above with reference to FIGS. 1 to 8C. The resilient balls are disposed between, on one side, a pressure plate or other pressure member (120) and on the other side the wear plate (110.6) of the roller end piece (110.3). The pressure member (120) is conveniently in the form of a circular plate and is so disposed that it rotates synchronously with the sprocket (112).
This synchronous operation can be effected, for example, by slots formed in the pressure plate to engage respectively the lugs (117) carried by the sprocket extension (116). The pressure plate includes a wear plate for contact with the resilient balls (119).
Thus, in terms of the general concept of the invention, the pressure plate (120) comprises the driving member and the pressure plate wear strip (120.1) comprises the driving surface; and the roller end piece (110.3) comprises the driven member and the roller end piece wear plate (110.6) comprises the driven surface.
The outer face (that is the face nearer sprocket 112) of the pressure plate (120) has formed therein three, like, inclined portions or ramps each of arcuate shape. These ramps can, for example, be identical with, or similar to, the ramps described above with reference to FIGS. 6A, 6B and 6C.
In between the outer face of the pressure member and the opposed inner face of the sprocket extension (116) there is disposed an adjustment ring (121) rotatably mounted on hub (113) and in contact with sprocket extension (116), whose purpose is similar to the adjustment ring described above with reference to FIGS. 7A to 7D, being formed on the face directly opposed to the outer face of pressure member (120) with inclined portions or ramps for co-operation with the ramps of the pressure member. The shape and dimensions of the ramps of the adjustment ring -24and/or stops are conveniently the same as, or similar to, those of the pressure member.
Adjustment ring (121) has slots or their equivalent, by means of which the ring can be engaged by a spanner or other tool to adjust the angular position of the ring. The ring preferably has a display of comparative values of torque. On its other face the adjustment ring has calibration means, for example a plurality of protrusions, depressions or engagement means for co operation with corresponding means carried by the opposed face of the sprocket extension (116).
Roller end piece (110.3) carries an outwardly extending circular flan5e (122) as an oil shie ld to prevent the ingress of oil onto the carrier (118).
In FIG. 9 the values of 1115.5 or 11.5 mm" for the dimension "XII are given by way of example.
MODE OF OPERATION OF THE SECOND EMBODIMENT The mode or method of operation of the embodiment described above with reference to FIGS. 9 and 10 can, for example, be similar to that described above with reference to FIGS. 1 to 8C but taking into account the f act that in the FIGS. 9 and 10 embodiment the torque limitation device lies inboard of the sprocket whereas in the FIGS. 1 to 8C embodiment the devices lies -25 outboard of the sprocket. In general terms, in thesecond embodiment the transmission of power from sprocket (112) to the roller (110) is provided, in succession by pressure member (120) as the driving member, resilient balls (119) and roller end piece (110.3) as the driven member. The adjustment ring or other adjustment means (121) is comprised by the ramp means of the pressure plate and the ramp means of the adjustment ring and (optionally) by the calibration means.
The resilient balls used in the embodiments of the invention described with reference to the drawings were either Elastollan C 90 A 55 000 or Elastollan C 98A 10 000. These elastomers have the following properties:
Elastollan C 90 A 55 000 Property Value Unit Test Method MFR g/10 min Density 1.20 0.01 g/cm' DIN 53479 Hardness shore A 93 2 DIN 53505 Hardness shore D Tensile strength 45 N/mm2 DIN 53504 Elongation at break ?:450 t DIN 53504 Tear strength 80 N/mm DIN 53515 Abrasion loss 35 mm 3 DIN53516 Elastollan C 98 A 10 000 Property Value Unit Test Method MFR g/10 min Density 1.22 0.01 g/cm, DIN53479 Hardness shore A 98 2 DIN 53505 Hardness shore D 52 3 Tensile strength 35 N/ffffn2 DIN53504 Elongation at break 400 01 DIN 53504 Tear strength 110 N/mm DIN53515 Abrasion loss 45 Tmn 3 DIN53516 REP/mw A1302. 25a A1302 -27-
Claims (21)
1. A torque limitation device which comprises:
a driving member having a driving surface; a driven member having a driven surf ace, said driving surface and said driven surface being so disposed as to define a gap between them; and, disposed in said gap and in frictional contact with the driving surface and the driven surface, a resilient f orce- transmitting means capable, in a first mode, of transmitting force from said driving member to said driven member and, in a second mode, of ceasing to transmit the force and to rotate while in contact with said driving surface and said driven surface; is characterised in that said device includes adjustment means for adjusting to a pre-determined extent the amount of compression of said resilient force-transmitting means when it is in said frictional contact with said driving surface and said driven surface, the adjustment means comprising a first element adapted for movement in a direction substantially transverse to said driven surface, and a second element 'operatively connected to the first element and adapted for rotatable movement thereby to effect said movement of the first element.
2. A torque limitation device according to Claim 1, wherein said movement of the first element results in adjustment of the size of said gap between said driving surface and said driven surface.
3. A torque limitation device according to Claim 1 or 2, wherein said first element is carried by, or is comprised by, the driven member.
4. A torque limitation device according to Claim 1, 2 or 3, wherein said second element is mounted co-axially with the driven member.
is
5. A torque limitation device according to any of the preceding claims, wherein a means operatively connecting the first and second elements comprises a ramp device comprising co-operating ramps disposed for relative motion while in face-to-face contact.
J
6. A torque limitation device according to Claim 1, wherein said driven member comprises a reaction plate, and the adjustment means includes an adjustment plate mounted co-axially and substantially parallel to the reaction plate for relative rotational movement and relative axial movement therewith; the opposed faces of the reaction plate and the adjustment plate each carries co-operating arcuate ramps disposed for face-to-face sliding contact, whereby relative movement between the cooperating arcuate ramps results in the reaction plate and adjustment plate being moved apart, thereby urging the reaction plate against the resilient force-transmitting means.
7. A torque limitation device according to any of Claims 1 to 6, wherein the f orce- transmitting means comprises one or more resilient rotatable elements carried by a carrier, said carrier being disposed between the driving and the driven surfaces for rotation about an axis of the carrier.
8. A torque limitation device according to Claim 7, wherein the carrier comprises a plate having formed therein a plurality of apertures or recesses each to accommodate a resilient rotatable element so as to be rotatable within its respective aperture or recess.
9. A torque limitation device according to Claim 8, wherein said apertures or recesses are disposed equi-angularly in the plate.
10. A torque limitation device according to Claim 8 or 9, wherein all of said elements are accommodated in apertures in said plate and all said elements are in contact with said driving surface and with said driven surface.
11. A torque limitation device according to any of Claims 7 to 10, wherein the elements are resilient balls and the apertures are circular.
12. A torque limitation device according to Claim 11, wherein the balls are spherical balls and, in use, they are compressed to the shape of a spheroid.
13. A torque limitation device according to Claim 12, wherein the major axis of the spheroid is disposed diametrically with respect to the respective circular aperture and the minor axis is disposed transversely to the respective circular aperture.
14. A torque limitation device according to any of Claims 7 to 13, wherein the driven surface has formed therein a plurality of like recesses disposed equi-angularly in said surface and each sequentially to receive said elements as they move relative to the driven surface.
15. A torque limitation device according to any of the preceding claims, wherein the driving member is a sprocket wheel and the 3 driven member is a reaction plate.
16. A torque limitation device according to Claim 1, substantially as described heein with reference to the accompanying drawings.
17. A torque limitation device substantially as described herein and substantially as shown in the accompanying drawings.
18. A roller conveyor in which one or more of the rollers are provided with a torque limitation device as claimed in any of the preceding claims.
19. A roller conveyor according to Claim 18, having a plurality of parallel rollers, said driving member is comprised by, or is secured to, a chain-driven sprocket wheel and said driven member is a member comprised by, or secured to, one of the rollers.
20. A roller conveyor according to Claim 18, substantially as described herein with reference to the accompanying drawings.
is
21. A roller conveyor as described herein and substantially as: shown in the accompanying drawings.
A 1302.19a
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9818480A GB2342412A (en) | 1998-08-26 | 1998-08-26 | Torque limitation device |
AU59483/99A AU5948399A (en) | 1998-08-26 | 1999-08-19 | Torque limitation device |
PCT/GB1999/002760 WO2000012910A1 (en) | 1998-08-26 | 1999-08-19 | Torque limitation device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9818480A GB2342412A (en) | 1998-08-26 | 1998-08-26 | Torque limitation device |
Publications (2)
Publication Number | Publication Date |
---|---|
GB9818480D0 GB9818480D0 (en) | 1998-10-21 |
GB2342412A true GB2342412A (en) | 2000-04-12 |
Family
ID=10837778
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9818480A Withdrawn GB2342412A (en) | 1998-08-26 | 1998-08-26 | Torque limitation device |
Country Status (3)
Country | Link |
---|---|
AU (1) | AU5948399A (en) |
GB (1) | GB2342412A (en) |
WO (1) | WO2000012910A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10907313B1 (en) | 2019-10-18 | 2021-02-02 | James P. Shea | Temporary tape removal hub for tape removal machine |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2290358A (en) * | 1993-02-15 | 1995-12-20 | Powerveyor Products Ltd | Torque limitation device |
GB2321504A (en) * | 1997-01-23 | 1998-07-29 | Moog Inc | Friction slip clutch |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1351150A (en) * | 1962-03-21 | 1964-01-31 | Gomma Antivibranti Applic | Energy dissipating device |
US3477252A (en) * | 1968-01-18 | 1969-11-11 | Ibm | Slip clutch |
DE1932790A1 (en) * | 1969-06-27 | 1971-01-07 | Inst Plasmaphysik Gmbh | Torque limiting clutch |
DE2305452A1 (en) * | 1973-02-03 | 1974-08-08 | Ruediger Dipl Ing Hoffmann | TORQUE LIMITER AS OVERLOAD PROTECTION DURING ROTATION AND / OR SPECIALLY FOR INSTALLATION IN THE HOUSING OF BELT ROLLERS |
DE2514738A1 (en) * | 1975-04-04 | 1976-10-14 | Herbert Brockel | Vehicle drive hydraulic torque coupling - has inclined contact surfaces between tapered rollers and coupling |
CA1063545A (en) * | 1976-05-14 | 1979-10-02 | Harry Major | Accumulating roll conveyor |
GB2214577B (en) * | 1988-02-01 | 1991-03-13 | John Graeme Walker | Sprocket clutch |
FR2673974B1 (en) * | 1991-03-14 | 1995-10-20 | Bellanger Robert | SECURITY DEVICE FOR A TILTING GARAGE DOOR. |
-
1998
- 1998-08-26 GB GB9818480A patent/GB2342412A/en not_active Withdrawn
-
1999
- 1999-08-19 WO PCT/GB1999/002760 patent/WO2000012910A1/en active Application Filing
- 1999-08-19 AU AU59483/99A patent/AU5948399A/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2290358A (en) * | 1993-02-15 | 1995-12-20 | Powerveyor Products Ltd | Torque limitation device |
GB2321504A (en) * | 1997-01-23 | 1998-07-29 | Moog Inc | Friction slip clutch |
Also Published As
Publication number | Publication date |
---|---|
AU5948399A (en) | 2000-03-21 |
GB9818480D0 (en) | 1998-10-21 |
WO2000012910A1 (en) | 2000-03-09 |
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Legal Events
Date | Code | Title | Description |
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WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |