Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
  • G01L5/04—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands
  • G01L5/06—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands using mechanical means

Definitions

• the subject invention concerns a device for indication of a predetermined tension of elongate flexible elements, primarily of belts incorporated in belt trans ⁇ missions, e. g. driving belts used in combustions engines and running around belt pulleys to drive the generator, the radiator fan, the servo pump, air conditioning unit, etcetera.
• ⁇ t is customary to simultaneously install the driving belt or belts driving the equipment items mentioned above.
• these belts are placed loosely around the various pulleys with the adjustment device of e.g. the generator in a non-tightened condition.
• the set screws of the adjustment device is then tightened by means of a suitable tool, such as a screw- driver, while at the same time the belt is tightened by means of another suitable tool, e.g. a lever acting on the generator so as to force the latter outwards.
• the magnitude of the belt tension is usually checked by the operator who, for instance with the aid of his thumb, depresses the belt at a point intermediate two adjacent pulleys, and the tightening force or belt tension is normally considered to be "correct” if the force exerted on the belt in this manner amounts to a depression corresponding approximately to 10 mm.
• this method does not make it possible to ascertain with sufficient certainty the actual value of the belt tension, in addition to which the tension may vary within very wide limits from one engine to the next. Some belts therefore wear out prematurely as a result of slippage.
• the driving belts are dimensioned for a com ⁇ paratively long serviceable life, which is a feature requested by the consumer, it is necessary to make arrangements ensuring that a value of the tensional force may be achieved in a reproduceable manner and at a carefully predetermined level with only very minute tolerance deviations.
• the purpose of the subject invention is to provide a device meeting the demands outlined above in a simple, rapid and reliable manner.
• the device comprise a base, a hub associated with the base and protruding therefrom and including a means for supporting the elongate element, two links pivotally connected to the base at their first, inner end and projecting in opposite directions from the base essentially at right angles to the hub, each link formed at its opposite, outer end with an abutment, said abutments being equidistantly spaced from the hub to support the elongate element, and a resiliently yielding member connected to the links and possessing a reactional force corresponding to the predetermined tension of the elongate element, said links being arranged for synchronized pivotal movement between two stable end positions while passing an imaginary line interconnecting the abutment means past the hub for snap- over movement, the elongate element arranged, when the links assume one of their end positions, to be moved to a position of abutment against the link abutments and the hub support surface and to be tightened upon the synchronized pivotal movement of the links against the action of the
• Fig. 1 illustrates the device in a front view which is partly cut in order to show the components behind
• Fig. 2 illustrates the same device in a view from above, and partly broken and partly cut along line II-II of Fig. 1
• Fig. 3 illustrates the device as seen from the left end in accordance with Fig. 1 and partly in a transverse sectional view.
• Fig. 4 shows one example of using the device to tighten driving belts of motor vehicle engines
• Figs. 5 - 7 illustrates successive sequences of the tightening operation.
• the device indicated generally by numeral 1 which device could also be called an indicator or a gauge, is intended to indicate the existence of a predetermined tension of the elongate flexible element 2.
• the flexible element 2 in accordance with the embodiment described is in the form of a conventional driving belt 31 of a combustion engine 3.
• the driving belt is wrapped around a driving pulley 4 mounted on the free end of a crankshaft 5, a generator pulley 6, and a radiator fan pulley 7.
• More than one driving belt 31 may be provided, for instance driving belts arranged in pairs, or driving belts arranged to drive additional equipment, such as the servo pump for servo control and air-condition compressors.
• the main components of the indicator 1 are a base 8 a hub 9, two links 10, each with an abutment 11, and a resiliently yieldable means 12.
• the base 8 comprises a rectangular metal support plate 13 with a recess 14 formed therein e.g. through milling and which recess, as seen from the front accordi to Fig. 1, extends horizontally between the opposite edg faces 15 of the support plate 13.
• the recess 14 is open the ends and is also open outwards, i.e. towards the fron as seen in Fig. 1.
• the. base 8 comprises a likewise rectangular covering plate 16 having the same outline configuration as the support plate 13 and also made from metal.
• the covering plate covers the support plate, and consequently the recess 14 formed therein, in the outward direction in such as manner that a through-channel is defined between the plates 13 and 16.
• the hub 9 has an essentially circular configuration and preferably it is made from metal or some suitable plastics material.
• the hub 9 projects from the base 8, in Fig. 1 towards the viewer, and it is secured to the base by means of an attachment plate 17 of metal having an outline configuration essentially agreeing with that of the support and coverin plates 13, 16.
• the attachment plate 17 comprises a centra circular aperture 18 with a shoulder 19 therein, in which aperture the hub 9 is rotationally mounted by means of a circularly cylindrical flange 20 abutting against the shoulder 19.
• the hub may be turned about its centre axis 21 for a purpose to be described in closer detail in the following.
• the support plate 13, the covering plate 16, and the attachment plate 17 are joined together by means of fasteners 22, for instance screws, rivets, and the like, with the plate side faces in abutting relationship in such a manner as to form a housing.
• the hub 9 has a support 23 for the belt 31 and in accordance with the embodiment illustrated the support is formed by a transverse slit 24 which is open outwards and at its ends " for reception of the belt 31.
• the slit 24 is essentially parallel with the recess 14 described in the aforegoing and comprises two parallel spaced-apart support faces 25, 26.
• these support faces are spaced different distances A and B from the centre axis 21 of the hub and are intended for different belts which, although of different thicknesses, are to be given the same degree of taugtness.
• the two links 10 are configured as elongate, rather flat arms and they, too, are preferably made from metal.
• the links 10 are pivotally mounted to the base 8, more precisely in the recess 14 of the support plate 13, and they extend in opposite directions therefrom, essentially at right angles to the hub 9.
• the links 10 and the support and covering plates 13, 16 are formed with aligned holes 28 for reception therein of pivot pins 29 or similar means for the pivotal connection of the links 10 to the base 8.
• each link 10 supports an abutment 11 for engagement with the belt 31.
• these abut ⁇ ments are in the shape of pins 32, each one of which projects in both directions from its associated link 10 in parallel with the hub 9.
• the pins 32 are spaced equal distances from the latter.
• One half of each pin 32 forms the abutment means II proper and projects in the same direction as the hub 9, thus allowing the belt 31 to run around these pin halves.
• the pins 32 thus project through attachment holes 33 formed in the associated links 10, and the other half of each pin protrudes from the face of the links 10 opposite the abutments 1.1 so as to form a member 34 on which may be attached the resiliently yieldable means 12.
• the resiliently yieldable means 12 is a helical tension sprin 35 the ends 36 of which are secured to the attachment member 34 of the pins 32, in this case by means of flat connective washers 37.
• a protective sleeve 38 of plastics or a similar material is threaded onto the helical tension spring 35.
• the helical tension spring 35 is dimensioned and calibrated so as to ensure that it exerts a reactional force corresponding to the predetermined tension of the belt 31. This reactional force or counter-force and tension, respectively, may typically mount to 425 + 25 N for a particular application.
• the links 10 described previously are arranged to be shifted in synchrony between two stable end positions, C in Fig. 1 and D in Fig. 7 while passing an imaginary line E interconnecting the abutments 11, past the hub 9, i.e. the centre axis 21 thereof, and thus to snap over from one to the other end position.
• the recess 14 in the support plate 13 described previously is formed with oblique abutment faces 39 adjacent its open ends near the plate edges 15.
• the inclination of each one of these oblique abutment faces 39 corresponds to essentially half the angle of pivo ⁇ ement, and under the action of the helical traction spring 35 the upper and lower edge faces 40, 41 on the links 10 may be moved to a position wherein they abut against the oblique abutments 39.
• this synchro ⁇ nizing mechanism Adjacent the inner ends of the links 10, at a point interiorly of the pivot pins 29, i.e. at a point inter- mediate the latter and the free link ends, see Figs. 1 and 2, a synchronizing mechanism 42 interconnects the links 10 to ensure their synchronized pivotal movement.
• this synchro ⁇ nizing mechanism comprises a metal pin 43 extending through aligned holes 44 formed in the links and having a height essentially agreeing with the thickness of each link, whereby it will be enclosed by the links and not interfere with the pivotal movement of the links about th pivot pins 29 in the recess 14.
• the links 10 are formed with facing recesses 45, whereby the innermost portions of the inner ends 27 of the links 10 will overlap and have face- o-face contact, the synchro ⁇ nizing mechanism 42 being arranged in the area of these end portions.
• the links 10 are formed with inner, evenly curved end edge faces 46, each in rolling abutment against its associated counter edge faces 47 formed by the point where the associated recess 45 merges into the links 10 and having straight side portions and a centrally positioned cam nose 48.
• the edge faces 46 and the counter edge faces 47 thus form cooperating cam faces which, upon synchroniz ⁇ ed pivotal movement of the links against the action of the helical tension spring 35 determine the point where the snap-over action is to take place.
• the hole 44 in one of the links 10 is essentially circular whereas the hole 44 in the opposite link is essentially oblong with its major axis extending in the lengthwise direction of the associated link.
• the pin 43 is allowed some lateral movement, in the embodiment illustrated over a distance corresponding to approximately 1/4 of the diameter of the pin 43, in compensation for the mutual lateral movement of the holes 44 over the same distance that will occur when the links 10 pivot about the pivot pins 29 from one to the other of the two stable end positions C, D defined by the abutments 39 in the recess 14.
• the function of the indicator 1 described in the aforegoing and illustrated in Figs. 4 - 7 is as follows:
• the belt 31 may be placed around and in abutment against the two abutment means 11 on the links and against one of the support faces 25 in the slit 24 of the hub 9.
• the belt 31 is then tightened, for instance by the generator pulley 6 being forced outwards, i.e. to the lef as seen in Fig. 4, while the links 10 are pivoted in syn ⁇ chrony against the action of the helical tension spring 35 until the belt 31 extends along an essentially straight line between the abutment means, see Fig. 6.
• the predetermined tension of the belt 31 agrees with the dimensioned and calibrated counter- force of the helical tension spring 35, and under the influence of said helical tension spring, it effects snap- over of the links 10 to their second upper and stable end position D, see Fig. 7.
• This snap-over movement is the audible and visible indication of obtainment of the predetermined tension of the belt 31.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)
• Tires In General (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20383364

Family Applications (1)

Country Status (6)

Cited By (2)

Citations (4)

Family Cites Families (3)

• 1991
  • 1991-07-22 SE SE9102218A patent/SE467277B/sv not_active IP Right Cessation
• 1992
  • 1992-07-17 EP EP92915937A patent/EP0621945B1/en not_active Expired - Lifetime
  • 1992-07-17 JP JP50244393A patent/JP3151218B2/ja not_active Expired - Fee Related
  • 1992-07-17 AU AU23334/92A patent/AU2333492A/en not_active Abandoned
  • 1992-07-17 WO PCT/SE1992/000520 patent/WO1993002343A1/en active IP Right Grant
  • 1992-07-17 DE DE69216857T patent/DE69216857T2/de not_active Expired - Fee Related

Patent Citations (4)

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