GB1583805A

GB1583805A - Chain drive arrangement incorporating an endless link chain

Info

Publication number: GB1583805A
Application number: GB28628/77A
Authority: GB
Original assignee: Ferag AG
Current assignee: Ferag AG
Priority date: 1976-07-09
Filing date: 1977-07-07
Publication date: 1981-02-04
Also published as: DE2730998A1; AR214413A1; FI772070A; JPS5337274A; PL120177B1; DD131666A5; ATA507876A; FR2357792A1; BR7704510A; DK310877A; IT1084649B; DK152861B; SE431633B; AU2662877A; NO772389L; CH621183A5; AT354196B; PL199455A1; AU513677B2; DK152861C

Abstract

The endless link chain of the chain drive is arranged in a chain duct (2) in which the chain joints (4) are guided. In operation, the chain is not tensioned because the length of the chain duct (2) is equal to the nominal length of the chain. As a result, the chain also has the same length at all times irrespective of the unavoidable play in the chain joints, although the chain is stretched in the section in which it runs towards the chain drive and compressed in the section following the drive. In the alternately loaded chain joints (4), the lubricant flows repeatedly between the load-bearing surfaces which have just been relieved. This chain drive can be used with advantage as a newspaper transporter in a newspaper printing machine. <IMAGE>

Description

(54) A CHAIN DRIVE ARRANGEMENT INCORPORATING AN ENDLESS LINK CHAIN (71) We, FERAG AG, a Swiss Company, of 8340 Hinwil, Switzerland, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: The present invention relates to a chain drive arrangement comprising an endless link chain which is arranged within and guided by a chain track or channel.

During operation of such a chain drive, the length of an endless link chain is always indefinite. Unavoidable play occurs between the chain links, which play increases as a result of wear, and the effect of such play upon the chain length, in the sense of lengthening or shortening thereof, always depends upon the local chain tension.

However, this local chain tension is subject to considerable fluctuations as a function of the position of the drive and power take-off and the momentary load, so that the chain length continuously correspondingly alters.

In other words: an endless chain, during operation, possesses an indefinite or undefined length, and the possible changes in length are accompanied by the jerky movement, jarring and impacts applied to the chain. It is for these reasons that attempts have been heretofore made to impart to the chain a defined or predetermined length with the aid of chain-tensioners or chain-stretching devices. What is decisive in this regard was the attempt to stretch the chain and thus to eliminate the play prevailing in the chain links. This concept, however, cannot be faithfully carried out in practice. The complete elimination of the play at the chain links requires, apart from the heretofore necessary enormous tensioning forces, the complete displacement of the lubricant, something which is obviously impossible.

However, if lubricant, even in the form of a thin film, is present at the hinges or joints, then play also exists which, with the unavoidable changes in tension, can be correspondingly reduced by displacement of the lubricant or can be shifted from the Qne to the other side of the pivotal axis of a hinge or joint, with the result that the changes in length cause noisy or unsteady chain travel. It may be also generally stated that suppression of noise associated with chain travel by means of chain-tensioners can only be accomplished within limits, so that even within practical limits, due to tensioning of the chain, there is a considerable increase not only in the drive power and the wear, but also in the re quirements placed upon the lubricant.

Hence, with the foregoing in mind, it is an object of the present invention to provide a construction of chain drive having an endless link chain which avoids or minimises the aforementioned drawbacks and limitations of the prior art proposals.

According to the present invention, there is provided a chain drive arrangement comprising: chain guide means having an endless track; an endless link chain arranged and guided in said track so as to be constrained to travel therealong; means operable to drive said endless link chain along said track; said link chain having a rated length (as hereinafter defined); and the length of the track being essentially equal to the rated length of the link chain; whereby when the endless link chain is driven by said drive means, the portion of the link chain in one zone of said track assumes a tensioned state, whereas the portion of said link chain in another zone of said track assumes a compressive state.

Each link of a chain is connected to its two neighbouring links for relative pivotal movement about two axes or centres which are in theory, i.e. in the absence of any play in their associated hinges or joints, a fixed distance apart. The term "rated length" as used in this specification and appended claims is defined as the latter-mentioned theorectical distance between the said axes or centres of pivotal movement of a chain link multiplied by the number of links in the chain.

This rated length is a theoretical value, which heretofore in practice had no significance, since with a chain drive of conventional type, during its operation, such a rated length did not exist because the actual distance between the two axes or centres of pivotal movement of each link varied due to play in the associated hinges or joints. If, however, the chain track is dimensioned in accordance with the rated length of the chain, then the latter is forced, during operation, to always exhibit that exactly defined length. In other words, and notwithstanding the degree of play which will in any case increase with time, the chain can no longer experience any changes in length, and consequently, quiet running of the chain results.

By virtue of the fact that the play between the chain links is not eliminated, but instead is retained whilst being rendered innocuous or harmless, an unexpected effect additionally arises. In a chain drive arrangement embodying the invention, as distinct from conventional chain drives, the non-stretched chain is subjected to pressure or compression in a zone following or downstream of the chain drive means, and is subjected to traction or tension in a zone leading or upstream of said drive means, whilst a uniform or steady transition occurs between these two zones. As a result the play present in the hinges or joints experiences uninterrupted, alternate changes, and the lubricant therefore is displaced alternately from one to the other of the upstream and downstream sides of the pivot axes. It would be also apt to state that the chain links "breathe". In contrast to conventional chain drives in which the link chains are continually held in a stretched condition by tensioning means, in the chain drive arrangement embodying the invention, even in the presence of extreme or unfavor able loads, the danger of the chain running dry or of the hinges or joints being in sufficiently lubricated despite the presence of lubricant, is avoided.

In order that the invention may be more readily understood, reference will now be made to the annexed drawing wherein the single Figure schematically illustrates a chain drive arrangement, having an endless link chain, constructed according to one embodiment of the present invention.

Turning now to the single Figure of the drawing there is illustrated therein a chain drive arrangement having an endless link chain 1 which is enclosed throughout its entire course or extent within chain guide means comprising an endless track 2, i.e.

a track forming or defining a closed loop or path. The chain 1 is driven around the track 2 by a chain drive 3. Each chain link, indicated generally at 4, at or adjacent its opposing ends, is connected to two neigh bouring links for relative pivotal or hinging movement about two axes or centres. More particularly, the chain links 4 include hinge sockets 5 which are guided in the track 2, and hinge bodies or balls 6 which are pivotally or swivellably retained in the hinge sockets of adjacent links. In accordance with the direction in which the link chain 1 travels or revolves around the track 2, indicated by the arrow P, within the zone or section of the track 2 which follows, i.e. is downstream of, the drive 3, the hinge bodies or balls 6 of one chain link are pushed by the hinge socket 5 of the next rearmost or downstream chain link. Consequently, the hinge play between the chain links in this zone is greater in front or downstream of the pivotal axes than rearwardly or upstream of the axes relative to the direction of motion of the link chain.

The reverse holds true in the zone or section of the track 2 preceding or upstream of the chain drive 3. Here, each chain link is pulled by the next forwardmost or upstream link, the play between the links in this zone is greater rearwardly or upstream of the pivotal axes relative to the direction of motion of the link chain 1. The lubricant will thus predominantly be located in the clearance space in the rear region of each hinge of the portion of the chain being drawn towards the drive 3, and after the drive 3, the clearance space and therefore the lubricant shifts over to the front region of each hinge of the portion of the chain being thrust away from the drive.

The result of this displacement of the lubricant is that sufficient lubrication and uniform wear of the hinge surfaces is obtained at all times.

The transition from thrust drive to traction drive, i.e. from the dammed-up chain section to the stretched chain section, is accomplished, as shown in the drawing, at location 7 of the track 2. The transition location 7 can therefore, depending upon the operating conditions, migrate, for instance as a function of the magnitude and position of the load. Moreover, what is decisive in this regard is the mutual coordination or matching of the length of the track to the rated length of the chain, so that the chain will neither be stretched nor dammed-up in its static condition. While observing this condition, it is however still possible to select the site of the transition location such that the individual chain links are loaded tensionally or compressively, respectively, along the same run or length, instead of as exemplified in the Figure in which the drive 3 is located in the upper run or length, the transition location is in the lower run or length, and the chain passes around the same number of curves while loaded under tension as while loaded under compression.

By virtue of the aforementioned measures the chain 1 travels effectively completely quietly in the guide or chain track 2 without being stretched or tensioned, and the chain links are always located in a stable guide position. In addition, the hinges, irrespec tive of the course or path prescribed by the chain track 2, and irrespective of whether one is concerned with a dam-up zone or a traction zone, are always supported in the track. Of course, the chain track 2 can be of any desired length and can follow any required course. If desired, the track can be provided with a number of chain drives.

The chain itself can be constructed in a number of different ways. Thus, for instance, ball-and-socket joints or link chains can be employed which can be twisted to a limited degree, and the hinges can possess sliding or rolling guide elements, quite independent of the remaining construction of the chain.

The chain guide means or track 2 itself can likewise take a variety of forms. In the case of a drive chain the track can take the form of a completely closed tube or duct which surrounds the chain. In the case of a conveying chain, the track can take the form of one or more channels defining one or more slots or equivalent structure extending around, i.e. lengthwise of, the track, as generally indicated at 10. Also, any suitable power take-off device, as indicated at 12, may be operatively associated with the link chain 1. In each case, the drive means 3 and the power takeoff means 12 can be arranged in respective closed housings 3a and 12a.

Without limiting the field of application of such chain drive arrangement, it is worthwhile mentioning at this point that the advantages are especially realized in the case of conveying or conveyor chains, which are often an appreciable length and follow a complicated course or path of travel. A preferred field of application of the described chain drive arrangement is its use in conjunction with newspaper transporting devices or the like.

The chain drive arrangement is not restricted to a particular length, nor must it follow a particular course or path. Consequently, the chain track or channel can be formed to its required length and path configuration by assembling together different elements, and can also be subsequently easily modified or changed. It is possible to employ, for instance, insertable or otherwise easily interconnectable track or channel elements. The same is also true for the construction of the chain links.

The described chain drive arrangement also, however, has particular significance in conjunction with drive chains insofar as the latter may now travel completely encapsulated and under effectively faultless lubrication conditions, for instance in an oil bath. Even the sprocket wheels or other drive or driven elements may then be located in closed housing, out of which there can sealingly protrude only the drive shaft or power take-off shaft, respectively.

As a modification it is possible for the chain track or channel, depending upon the proper ties of the chain and its division, to also possess interruptions, especially in the trac tion or tension zone. A chain track or channel which is slotted or interrupted in particular sections, or along its entire length, allows (possibly without otherwise altering the course of travel of the chain) the anchorage of units for the drive or power take-off at random locations, for instance, by attachment to the chain track or channel. In this way the versatility of the chain drive arrangement is increased, especially if the chain track or channel is composed of elements which can be easily coupled with one another.

In any event, a relatively light holder or support for the chain track or channel is required, and heavy foundations are not required.

In each embodiment of the chain drive arrangement a relatively jerk-free start-up is achieved, especially at moderate speeds, and this is accomplished notwithstanding the fact that the play in the hinges or joints is not eliminated, as is otherwise usual, for instance, with the aid of chain-tensioners.

On the contrary, the described chain drive arrangement gains the benefit from the play, which was heretofore considered to be disadvantageous, in that the aforementioned "breathing" of the chain links increases the loadability and longevity of the link chain. This is also true even when using plastic in (lubricant-free) joints or hinges, since such material often tends to flow when under continuous load.

WHAT WE CLAIM IS: 1. A chain drive arrangement comprising: chain guide means having an endless track; an endless link chain arranged and guided in said track so as to be constrained to travel therealong; means operable to drive said endless link chain along said track; said link chain having a rated length (as hereinbefore defined); and the length of the track being essentially equal to the rated length of the link chain; whereby, when the endless link chain is driven by said drive means, the portion of the link chain in one zone of said track assumes a tensioned state, whereas the portion of said link chain in another zone of said track assumes a compressive state.

2. The chain drive arrangement as claimed in claim 1, wherein said drive means for the link chain is arranged along the course of the chain guide means and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. By virtue of the aforementioned measures the chain 1 travels effectively completely quietly in the guide or chain track 2 without being stretched or tensioned, and the chain links are always located in a stable guide position. In addition, the hinges, irrespec tive of the course or path prescribed by the chain track 2, and irrespective of whether one is concerned with a dam-up zone or a traction zone, are always supported in the track. Of course, the chain track 2 can be of any desired length and can follow any required course. If desired, the track can be provided with a number of chain drives. The chain itself can be constructed in a number of different ways. Thus, for instance, ball-and-socket joints or link chains can be employed which can be twisted to a limited degree, and the hinges can possess sliding or rolling guide elements, quite independent of the remaining construction of the chain. The chain guide means or track 2 itself can likewise take a variety of forms. In the case of a drive chain the track can take the form of a completely closed tube or duct which surrounds the chain. In the case of a conveying chain, the track can take the form of one or more channels defining one or more slots or equivalent structure extending around, i.e. lengthwise of, the track, as generally indicated at 10. Also, any suitable power take-off device, as indicated at 12, may be operatively associated with the link chain 1. In each case, the drive means 3 and the power takeoff means 12 can be arranged in respective closed housings 3a and 12a. Without limiting the field of application of such chain drive arrangement, it is worthwhile mentioning at this point that the advantages are especially realized in the case of conveying or conveyor chains, which are often an appreciable length and follow a complicated course or path of travel. A preferred field of application of the described chain drive arrangement is its use in conjunction with newspaper transporting devices or the like. The chain drive arrangement is not restricted to a particular length, nor must it follow a particular course or path. Consequently, the chain track or channel can be formed to its required length and path configuration by assembling together different elements, and can also be subsequently easily modified or changed. It is possible to employ, for instance, insertable or otherwise easily interconnectable track or channel elements. The same is also true for the construction of the chain links. The described chain drive arrangement also, however, has particular significance in conjunction with drive chains insofar as the latter may now travel completely encapsulated and under effectively faultless lubrication conditions, for instance in an oil bath. Even the sprocket wheels or other drive or driven elements may then be located in closed housing, out of which there can sealingly protrude only the drive shaft or power take-off shaft, respectively. As a modification it is possible for the chain track or channel, depending upon the proper ties of the chain and its division, to also possess interruptions, especially in the trac tion or tension zone. A chain track or channel which is slotted or interrupted in particular sections, or along its entire length, allows (possibly without otherwise altering the course of travel of the chain) the anchorage of units for the drive or power take-off at random locations, for instance, by attachment to the chain track or channel. In this way the versatility of the chain drive arrangement is increased, especially if the chain track or channel is composed of elements which can be easily coupled with one another. In any event, a relatively light holder or support for the chain track or channel is required, and heavy foundations are not required. In each embodiment of the chain drive arrangement a relatively jerk-free start-up is achieved, especially at moderate speeds, and this is accomplished notwithstanding the fact that the play in the hinges or joints is not eliminated, as is otherwise usual, for instance, with the aid of chain-tensioners. On the contrary, the described chain drive arrangement gains the benefit from the play, which was heretofore considered to be disadvantageous, in that the aforementioned "breathing" of the chain links increases the loadability and longevity of the link chain. This is also true even when using plastic in (lubricant-free) joints or hinges, since such material often tends to flow when under continuous load. WHAT WE CLAIM IS:

1. A chain drive arrangement comprising: chain guide means having an endless track; an endless link chain arranged and guided in said track so as to be constrained to travel therealong; means operable to drive said endless link chain along said track; said link chain having a rated length (as hereinbefore defined); and the length of the track being essentially equal to the rated length of the link chain; whereby, when the endless link chain is driven by said drive means, the portion of the link chain in one zone of said track assumes a tensioned state, whereas the portion of said link chain in another zone of said track assumes a compressive state.

is secured thereto.

3. The chain drive arrangement as claimed in claim 2, wherein said drive means includes structure for driving the chain arranged in a closed housing.

4. The chain drive arrangement as claimed in claim 1, 2 or 3, including power take-off means provided for said link chain.

5. The chain drive arrangement as claimed in claim 4, wherein the power take-off means is arranged along the course of the chain guide means and is secured thereto.

6. The chain drive arrangement as claimed in any preceding claim, wherein the chain guide means surrounds the link chain.

7. The chain drive arrangement as claimed in any of claims 1 to 5, wherein said chain guide means is in the form of a channel having at least one lengthwise extending slot defining the track.

8. The chain drive arrangement as claimed in any preceding claim, wherein the link chain is devoid of any chain-tensioning means.

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