US3817113A

US3817113A - Chain drive with idler wheel tensioning means biased by elongated pads

Info

Publication number: US3817113A
Application number: US00215590A
Authority: US
Inventors: E Pfarrwaller
Original assignee: Sulzer AG
Current assignee: Sulzer AG
Priority date: 1971-01-18
Filing date: 1972-01-05
Publication date: 1974-06-18
Anticipated expiration: 1991-06-18

Abstract

The chain drive has one run deflected and biased about a tensioning wheel which is mounted on a pivotal support. The support is, in turn, mounted on a pivot axis by means of an elongated tension spring element made up of a pair of concentric tubes and a resilient material between the tubes. The resilient material allows deflection of the support when an abrupt tension force is imparted to the chain as in the case upon braking.

Description

United States Patent 1 1 1111, 3 7, Pfarrwaller June 18, 1974 CHAIN DRIVE WITH IDLER WHEEL 1,982,299 11/1934 Hapgood 74/24211 R TENSIONING MEANS E BY 2,087,253 7/1937 Herold 248/374 ELONGATED PADS 3,136,170 6/1964 Murray 74/242.ll R 3,391,807 7/1968 Buschbom... 74/242.1 R 75 l t: Ew'nPf 'll ,W't th, I 1 or f,{, er er FOREIGN PATENTS OR APPLICATIONS 1 380,671 9/1964 S t l d [73] Asslgneel g l f f Wmterthur, 413,422 7/1934 01151 132 2311] 74/24211 B w1 zer an [22] Filed: Jan. 5, 1972 Primary Examiner-Benjamin W. Wyche Assistant Examiner-Allan Russell Burke [21] Appl' 215590 Attorney, Agent, or Firm-Kenyon & Kenyon Reilly Carr & Chapin [30 Foreign Application Priority Data Feb. 5, 1971 Switzerland 724/71 [57] ABSTRACT 52 us. (:1. 74/2421 R 74/24211 R The Chain drive has One deflected and biased [51] Int. Cl. Fl6h 7/12 about a tensioning wheel which mounted on a 5s 1 Field ofSearch ..74/242.15 11,2421 R, otal Support The Support is, in mounted a 74/242 1 119342; "i" 1f f *j3' pivot axisby means of an elongated tension spring ele- 7 2 ment made up of a pair of concentric tubes and a resilient material between the tubes. The resilient mate- [56] References Cited rial allows deflection of the support when an abrupt tension force is imparted to the chain as in the case UNITED STATES PATENTS uponrbraking 622,526 4/1899 Nies et al 74/240 1,045,875 12/1912 Nilsen 16/189 9 Claims, 7 Drawing Figures CHAIN DRIVE IDLER WHEEL TENSIONING MEANS BIASED BY ELONGATED PADS This invention relates to a chain drive and, more particularly, to a means for absorbing tension in the chain of a chain drive. Still more particularly, this invention relates to a chain drive for textile machines.

As is known, chain drives may be used, for example, to drive a dobby such as a cam or card dobby or to drive a Jacquard mechanism. Such drives may have to be abruptly stopped and re-started, for example, in the event of yarn breakage, so that the chain has to take considerable tension duringsuch abrupt stopping and starting.

According to the present invention, a chain drive is provided with a means to absorb the tension imparted to the chain. This means includes a chain tensioning wheel situated on a pivotal support, and an elongate torsion spring element situated between the support and the pivotal axis and extending in a direction parallel with the axis; The plane containing the tensioning wheel substantially coincides with a central plane perpendicular to the axis which passes through the center of the torsion spring element.

The inclusion of the torsion spring element means that the chain does not have to take the considerable tension during abrupt stopping and starting but can momentarily yield slightly while the chain tensioning wheel moves away from the chain. In the event of an abrupt tension being imposed on the chain, the torsion spring element is stressed uniformly on either side of the tensioning wheel and the central plane without any tilting.

Conveniently, the drive includes a chain deflector wheel which is concentric with the axis. Thus, the direction of the chain run which arrives at the deflector wheel is kept constant. The drive may include a slideway for the chain which is situated upstream of the deflector wheel. In this way, the chain is prevented from rattling or undergoing any appreciable deflection due to vibration.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a first embodiment of a chain drive according to the invention;

FIG. 2 illustrates a view taken on line ll-II of FIG. 1.

FIG. 3 illustrates a second embodiment of a chain drive according to the invention;

FIG. 4 illustrates a view taken on line lV-IV of FIG.

FIG. 5 illustrates a third embodiment of a chain drive according to the invention; and

FIGS. 6 and 7 illustrates views taken on lines VI-VI and VII-VII of FIG. 5, respectively.

Referring to FIG. 1, a shaft 1 carries a driving sprocket wheel 2 and rotates, for example, at the same speed as a main shaft (not shown).of an associated loom. A sprocket wheel 5 mounted on a shaft 6 is driven in the direction of arrow 4 via a roller link chain 3. A Jacquard mechanism (not shown) is driven from the shaft 6.

In order to absorb tension in the chain 3, a toothed chain tensioning wheel 7 is situated to mesh in one run 3a of the chain 3. The wheel 7 is rotatably mounted on 2 two bearing parts 9 (FIG. 2) between which a ballor roller bearing 8 is disposed. The wheel 7 rotates about a spindle 11 which is secured in: two parallel rocking arms 12 by means of a screw connection 13.

Referring to FIG. 2, the rocking arms 12 form the support for the chain tensioning wheel 7. One end of each of the arms 12 is welded at 14 to an outer square tube 15 which encloses an inner square tube 16. Between the

square tubes

15 and 16 are disposed four pads 17 of resilient material, for example, of rubber. Each pad 17 is elongated and is initially disposed to lie between a flat side of the tube 16 and a corner of the outer tube 15. The inner square tube 16 encloses a fixed spindle 19 which is secured to a base plate 22 by means of a screw connection 21. At the right hand end of the spindle 19 (as viewed) a retaining ring 23 is secured by a screw 24 so as to bear on the inner square tube 16. The base plate 22 is arranged to move on the machine frame 27 of an associated Jacquard mechanism (not shown) by means of screws 25 and slots 26.

The parts 15, l6, l7 fonn a torsion spring element. As will be apparent from FIG. 2, the torsion spring element l5 17 extends longitudinally outwardly on both sides of the plane of the support arms 12 in parallel relationship to the fixed spindle 19. A central plane 20 which passes through the center of the total length of the spring element contains the plane of the chain tensioning wheel 7 and extends perpendicularly to the spindle 19. Consequently, when the tensioning wheel 7 pivots as described hereinbelow, the loading or stressing of the torsion spring element 15 17 and more particularly of the pads 17 is symmetrical and uniform on either side of the plane 20.

Referring to FIG. 1, the torsion spring element 15 17 is shown in a tensioned (twisted) position. In this position, the element tends to turn the outer square tube 15 and hence the arms 12 in an anti-clockwise direction as viewed back into the untensioned (untwisted) position in which the pads are disposed between the flat walls'of the inner tube 16 and the respective corners of the outer tube 15. Consequently, the chain tensioning wheel 7 is continuously pressed against the chain run 3a. If the Jacquard mechanism and the associated loom have to be stopped abruptly,'for example, due to a weft or warp yarn breakage, the mechanism and loom are braked and a force component 28 occurs in the chain 3 and momentarily urges the tensioning wheel 7 to the right as viewed. Under these conditions, the force exerted on the wheel 7 by the torsion spring element 15 17 is temporarily exceeded and the wheel 7 moves slightly to the right. When the instantaneous high braking force on the chain 3 ceases, the tensioning wheel 7 is returned to the left to the position illustrated as a result of the force exerted by the torsion spring element 15 17.

Once the yarn breakage in the loom has been cleared and the loom and the Jacquard mechanism have been re-started there is an increased tension in the chain 3, together with a force component 28 so that the reciprocating movement of the tensioning wheel 7 described above is repeated.

Referring to FIGS. 3 and 4, wherein like reference characters indicate like parts as above, rocking arms 12a are used as supports for the tensioning wheel 7 and the arms have projections 31 extending beyond the torsion spring element. A stop formed from a square web 32 is situated between the projections and a buffer 33 of resilient material, for example, of rubber, is situated on the web 32. An arm 34 is also secured, for example by shrinking, onto the fixed spindle l9 and carries an adjusting screw 35 at the free lower end. The screw 35 is situated in a screw-thread 37 which can be radially tightened by means of a screw 36, and co-operates with the

stop

32, 33.

The screw 35 serves to adjust the degree of prestressing of the torsion spring element 15 17. For example, referring to FIG. 4, the nut 21 can be released and the

tensioningwheel unit

7, 12a, 15 17, 34 can be removed completely from the plate 22. The screw 36 is then moved to permit the screw 35 to be turned, for example, until the projections 31 and the arm 34 are farther apart. The stress in the rubber pads 17 is thus increased. The screw 36 is re-tightened in a suitable position and the tensioning wheel unit is fitted into the plate 22 and secured by the nut 21 in a position such that the chain wheel 7 is operative, with practically no tension, simply to deflect the chain 3 as shown in FIG. 3. The torsion spring element 15 17 is then pre-stressed. Only when the pull on the chain 3 increases, for example, during a sudden stopping or starting, is the pre-stressing force momentarily overcome by the additional force component 28 and the chain tensioning wheel 7 temporarily pivoted in a clockwise direction as viewed in FIG. 3.

Referring to FIGS. to 7, wherein like reference characters indicate like parts as above, rocking arms 12b are used which, as shown in FIG. 7, contain the stop 32 for the adjusting screw 35. The screw 35 is mounted in a projection 38 on a ring 39 secured on the fixed spindle 19.

The outer square tube and the inner square tube 16 of the torsion spring element 15 17 are split as can be seen in FIG. 6. A chain deflecting wheel 42 is rotatably mounted between the two parts of the inner square tube 16 and between the wheel 42 and the two parts of the tube is a roller bearing 41. The chain run 3a passes through a slideway 43 while the run 3b passes through a slideway 44. The slideways prevent transverse movements of the chain due to vibration.

The effect of the deflector wheel 42 is such that the direction of the chain run 3a in the region of the slideway 43 remains constant if the tensioning wheel 7 is temporarily pivoted in the clockwise direction as a result of a sudden force component 28. Since the direction of the chain run upstream of the deflector wheel 42 is constant, the slideway 43 can be used for this run of the chain although the pivotable tensioning wheel 7 is provided. The chain tensioning unit 15 17, 19, 7, 41, 39 is screwed onto the base plate 22 by means of a tensioning ring 46 and screws 47.

In all the embodiments, the plane containing the chain tensioning wheel 7 coincides with the central plane of the torsion spring element 15 17. The chain tensioning wheel 7 is always mounted in the rock ing arms 12 which are symmetrical with respect to the central plane 20; the arrangement is always such that the rocking arms 12 forming the support are secured symmetrically of the central plane 20 on the outer square tube 15 of the torsion spring element 15 17. The welding of the arms 12 to the outer tube 15 maintains the symmetry and thus prevents any tilting of the tensioning wheel 7 in the event of sudden loading by the chain 3.

In a modified embodiment, a chain tensioner, for example, as in the embodiments described, may be pro vided on the chain run 3b so that two chain tensioners are provided. The tensioning wheel 7 may, if required,

be shifted slightly out of the central plane 20. Depending on the size of the components, the maximum amount for this is a few millimeters, and in any case must be such as to avoid any harmful unsymmetrical loading and stressing of the torsion spring element 15 17.

The chain drive can be advantageously applied to machines other then textile machines, particularly if increased tension occurs in a roller link chain 3 for a brief period during operation or if such increased tension must be expected.

Other possible constructions are those in which the torsion spring element 15 17 is not pre-stressed. In that case, for example, as shown in FIGS. 1 and 2, the chain tensioning unit 15 l7, 7, 19, is screwed on to the base plate 22 by means of the screw 21 so that the chain run 3a is simply deflected and is practically unstressed by the tensioning wheel 7 during normal operation. When the increased tension occurs, for example on stoppage, and when the tensioning wheel 7 is pivoted due to the corresponding force component 28, there is no pre-stressing of the torsion spring element 15 17 to be overcome so that even a relatively slight force component 28 will temporarily pivot the wheel 7.

a toothed chain tensioning wheel rotatably mounted on said support for engaging a travelling chain; and

an elongated torsion spring element secured to said support about said pivot axis and extending longitudinally outwardly on both sides of the plane of said support parallel to said pivot axis, said tensioning wheel being disposed in a central plane perpendicular to said pivot axis with said plane passing through the center of said torsion spring element, said spring element including a pair of concentric tubes and a plurality of elongated pads of material between said tubes.

2. A chain drive as set forth in claim 1 which further includes a chain deflector wheel rotatably mounted on said support concentrically of said pivot axis for deflecting a travelling chain therearound.

3. A chain drive as set forth in claim 2 which further includes a chain slideway situated upstream of said deflector wheel relative to the direction of travel of a chain passing therebetween.

4. A chain drive as set forth in claim 1 wherein said support is secured to the outer tube of said concentric tubes.

5. A chain drive as set forth in claim 1 wherein said support includes a pair of arms situated symmetrically of said central plane.

6. In combination with a chain drive including an endless chain having a pair of runs and means for driving said chain; means for absorbing tension in at least one of said runs, said means including a support pivotally mounted about a pivot axis transverse to said support, a toothed tensioning wheel rotatably mounted on said support and engaging said one run, and an elongated torsion spring element secured to said support about said pivot axis and extending longitudinally outwardly on both sides of the plane of said support parallel to said pivot axis, said spring element including a pair of concentric tubes and a plurality of elongated pads of resilient material between said tubes with said support secured to the outer tube of said concentric tubes, said tensioning wheel being disposed in a central plane perpendicular to said pivot axis with said plane passing through the center of said torsion spring element.

7. The combination as set forth in claim 6 wherein outer tube of said concentric tubes.

Claims

1. A chain drive including a support pivotally mounted about a pivot axis transverse to said support; a toothed chain tensioning wheel rotatably mounted on said support for engaging a travelling chain; and an elongated torsion spring element secured to said support about said pivot axis and extending longitudinally outwardly on both sides of the plane of said support parallel to said pivot axis, said tensioning wheel being disposed in a central plane perpendicular to said pivot axis with said plane passing through the center of said torsion spring element, said spring element including a pair of concentric tubes and a plurality of elongated pads of material between said tubes.

7. The combination as set forth in claim 6 wherein said spring element is pre-stressed to urge said wheel against said one run.

8. The combination as set forth in claim 7 wherein said means further includes an adjusting means for adjusting the amount of pre-stress of said wheel against said one run.

9. The combination as set forth in claim 6 wherein said spring element includes a pair of concentric tubes and a plurality of elongated pads of resilient material between said tubes and said support is secured to the outer tube of said concentric tubes.