DE102016209598B4 - Pulley decoupler - Google Patents

Abstract

Belt pulley decoupler (1, 1 ') for the transmission of drive torque between the belt of a starter-generator belt drive and the starter generator, comprising: - a belt pulley (2), - a hub (4, 4') to be attached to the generator shaft of the starter generator, - a decoupler spring ( 11, 11 '), which transfers the drive torque of the belt from the belt pulley (2) to the hub (4, 4') when the starter generator is driven, - and a lock that transfers the drive torque of the generator shaft from the hub (4, 4 ') to the belt pulley (2), characterized in that the lock is formed by a loop band (12, 12') which in the drive torque flow between the belt pulley (2) and the hub (4, 4 ') parallel to the decoupler spring (11, 11 ') and when the starter generator is driving, the belt pulley (2) loops against the hub (4, 4') in a torsionally rigid manner.

Description

• - eine Riemenscheibe,
• - eine auf der Generatorwelle des Startergenerators zu befestigende Nabe,
• - eine Entkopplerfeder, die bei angetriebenem Startergenerator das Antriebsmoment des Riemens von der Riemenscheibe auf die Nabe überträgt,
• - und eine Sperre, die bei antreibendem Startergenerator das Antriebsmoment der Generatorwelle von der Nabe auf die Riemenscheibe überträgt.

The invention relates to a pulley decoupler for the transmission of drive torque between the belt of a starter-generator belt drive and the starter-generator. The pulley decoupler includes:

• - a pulley,
• - a hub to be attached to the generator shaft of the starter generator,
• - a decoupling spring which, when the starter generator is driven, transfers the drive torque of the belt from the pulley to the hub,
• - and a lock that transfers the drive torque of the generator shaft from the hub to the pulley when the starter generator is driving.

Pulley decouplers (referred to as 'decouplers' or 'isolators' in the English-language specialist literature) compensate for torsional vibrations and irregularities that are introduced by the crankshaft of an internal combustion engine into its auxiliary unit belt drive, and are typically arranged on the generator. If the generator is a starter generator that drives the internal combustion engine in the electric motor mode for starting or boosting via the belt drive, the usual overtaking of the generator shaft with generator freewheels is not possible without further ado. Rather, the pulley decoupler must lock in this relative direction of rotation in order to be able to transmit the drive torque generated by the starter generator to the belt via the hub and pulley.

A generic pulley decoupler is from the EP 2 010 792 B1 famous. The lock, which transfers the drive torque from the hub to the pulley when the starter generator is driving, is formed there by circumferentially fixed end stops that limit the rotatability of the hub relative to the pulley. A major disadvantage of the fixed stops is the high level of noise that increases with the speed of the hub against the pulley.

Another generic pulley decoupler is from EP 1 730 425 B1 known and constructed in such a way that the decoupler spring is a helical torsion spring which can be loaded in both directions of rotation, ie in the opening and closing directions. In one direction of rotation, the spring transmits the drive torque emanating from the belt to the starter generator in a decoupling manner, and in the other direction of rotation the spring acts as a loop band that changes its diameter, which either opens or contracts due to the start or boost torque and the pulley is torsionally rigid against the Hub loops. A disadvantage of this construction is the considerable difficulty in satisfactorily realizing the different functions of the spring and the loop tape in the same component.

Further pulley decouplers are from the DE 11 2015 000 381 T5 , the WO 2015/103 697 A1 and the DE 11 2013 002 101 T5 famous.

Proceeding from this, the present invention is based on the object of specifying a pulley decoupler of the type mentioned at the beginning with an alternative embodiment of the lock.

The solution for this results from the features of claim 1. According to this, the lock should be formed by a loop belt that is connected in the drive torque flow between the pulley and the hub parallel to the decoupler spring and, when the starter generator is driving, loops the pulley against the hub in a torsionally rigid manner.

In contrast to the above-mentioned belt pulley decoupler with fixed stops, the loop strap causes a comparatively gentle locking process of the belt pulley with respect to the hub when the starter generator begins to transmit the drive torque from the hub to the belt pulley. In addition, the lock, which is designed as a separate loop tape, enables an optimal design of the decoupling spring and loop tape, since it is largely independent of one another.

The loop tape is preferably in engagement with the belt pulley on the one hand and the hub on the other hand via a (circumferential) form fit of the loop tape ends. The form fit of the loop tape ends can be designed in such a way that it acts either unidirectionally in only one or bidirectionally in both relative directions of rotation from the belt pulley to the hub. For this purpose, the looping belt can have looping belt ends angled in the axial direction of the belt pulley decoupler which engage in recesses in the belt pulley and the hub. Alternatively, the loop tape ends can be shaped as legs deviating circumferentially from the circular shape, which positively engage in corresponding receptacles on the part of the belt pulley and the hub.

1. a.) wenn sich das Schlingband in entlastetem Zustand bereits in Reibeingriff mit dessen Reibkontaktpartnern an der Nabe und an der Riemenscheibe befindet, dann tordiert der Formschluss das Schlingband bei angetriebenem Startergenerator zweckmäßigerweise entgegen dessen Schlingrichtung, um ein ungewolltes Sperren des Schlingbands bei den entkoppelnden Relativverdrehungen der antreibenden Riemenscheibe gegenüber der Nabe zuverlässig zu verhindern. Ein auch in dazu entgegen gesetzter Relativdrehrichtung wirkender Formschluss ist optional und unterstützt den Sperrvorgang des Schlingbands bei antreibendem Startergenerator.
2. b.) wenn sich das Schlingband in entlastetem Zustand (mit Radialspiel) außer Reibeingriff mit dessen Reibkontaktpartnern an der Nabe und an der Riemenscheibe befindet, dann tordiert der Formschluss das Schlingband bei antreibendem Startergenerator zweckmäßigerweise in dessen Schlingrichtung, um das Schlingband zuverlässig in den zum Sperrvorgang führenden Reibeingriff mit dessen Reibkontaktpartnern zu bringen. Ein auch in dazu entgegen gesetzter Relativdrehrichtung wirkender Formschluss ist optional und erhöht die Sicherheit des Schlingbands gegen ungewolltes Sperren des Schlingbands bei den entkoppelnden Relativverdrehungen der antreibenden Riemenscheibe gegenüber der Nabe.

The version with unidirectional or bidirectional positive locking depends primarily on the installation conditions of the loop tape in the pulley decoupler:

1. a.) If the looped belt is already in frictional engagement with its frictional contact partners on the hub and on the pulley in the relieved state, the form fit twisted the looped belt appropriately against its looping direction when the starter generator is driven, in order to prevent the looping belt from locking undesirably during the decoupling relative rotations reliably prevent the driving pulley from the hub. A form fit that also acts in the opposite direction of relative rotation is optional and supports the locking process of the loop strap when the starter generator is driving.
2. b.) if the loop belt is in the relieved state (with radial play) out of frictional engagement with its frictional contact partners on the hub and on the pulley, then the form fit twists the loop belt appropriately in its looping direction when the starter generator is driving, in order to reliably move the loop belt into the locking process to bring leading frictional engagement with its frictional contact partners. A positive fit that also acts in the opposite direction of relative rotation is optional and increases the security of the loop tape against unintentional locking of the loop tape during the decoupling relative rotations of the driving belt pulley with respect to the hub.

The radial play simplifies the installation of the loop tape to a considerable extent, since the loop tape can be mounted axially without force or at least with little force via or in its frictional contact partner. The form fit acting in the looping direction makes it possible to pretension the looping belt in the looping direction after its axial assembly in order to achieve the torque-free transition angle of the pulley decoupler when the load changes between the driven starter generator - the decoupler spring is currently largely or completely relaxed and the looping belt does not yet lock - and driving Starter generator - the loop tape begins to block - to minimize.

In an alternative torque identification of the decoupler spring and loop tape, a comparatively large transition angle may be required in the named load change range of the pulley decoupler.

The decoupler spring is preferably a helical torsion spring extending in the axial direction of the pulley decoupler with legless spring ends which, when the starter generator is driven, transfer the drive torque from the step of an axially ramp-shaped spring plate of the pulley to the step of an axially ramp-shaped spring plate of the hub.

1. a.) größer ist, falls das Schlingband die Entkopplerfeder umschließt, oder
2. b.) kleiner ist, falls die Entkopplerfeder das Schlingband umschließt.

The torque curve during the locking process of the loop tape can also be influenced by the fact that the loop tape in a central section that loops against the pulley and against the hub has a different diameter than the loop tape ends, the diameter of the central section either

1. a.) is larger, if the loop tape encloses the decoupler spring, or
2. b.) is smaller if the decoupler spring encloses the loop tape.

The radial play, which changes in the axial direction between the loop tape and its frictional contact partners, leads in both cases to a progressive torque characteristic with correspondingly “soft” engagement, since the individual turns of the loop belt do not engage with the frictional contact partners at the same time, but successively. In case a.) The wound body of the loop tape has a bulbous shape and in case b.) A centrally constricted shape.

The successive engagement of the loop tape can alternatively or additionally also be achieved by a non-cylindrical shape of the frictional contact partners. When the looped belt is in the relaxed state, the radial play difference between the narrowest point between looped belt and frictional contact partner and the widest point between looped belt and frictional contact partner should be up to about 1 mm.

• 1 den ersten Riemenscheibenentkoppler in perspektivischem Längsschnitt;
• 2 den ersten Riemenscheibenentkoppler in perspektivisch explodierter Darstellung;
• 3 das Schlingband gemäß 2 in vergrößerter Einzelteildarstellung;
• 4 die Riemenscheibe des ersten Riemenscheibenentkopplers in perspektivischer Einzelteildarstellung;
• 5 die Nabe des ersten Riemenscheibenentkopplers in perspektivischer Einzelteildarstellung;
• 6 die Drehmomentkennung der Riemenscheibenentkoppler in schematischer Diagrammdarstellung;
• 7 den zweiten Riemenscheibenentkoppler in perspektivischem Längsschnitt;
• 8 das Schlingband des zweiten Riemenscheibenentkopplers in perspektivischer Einzelteildarstellung.

Further features of the invention emerge from the following description and from the drawings, in which two exemplary embodiments of belt pulley decouplers according to the invention for a starter-generator belt drive of an internal combustion engine are shown. Show it:

• 1 the first pulley decoupler in perspective longitudinal section;
• 2 the first pulley decoupler in an exploded perspective view;
• 3 the loop tape according to 2 in an enlarged detail view;
• 4th the pulley of the first pulley decoupler in a perspective detail view;
• 5 the hub of the first pulley decoupler in a perspective detail view;
• 6th the torque characteristics of the pulley decouplers in a schematic diagram;
• 7th the second pulley decoupler in perspective longitudinal section;
• 8th the loop tape of the second pulley decoupler in a perspective view of individual parts.

the 1 and 2 show the first pulley decoupler 1 in longitudinal section or as an explosion. A hollow cylindrical pulley 2 , whose outer jacket wrapped around by the belt 3 is profiled according to the poly-V shape of the belt, the belt in the in 2 shown direction of rotation. The pulley 2 is rotatable on a hub 4th stored, which is firmly screwed to the generator shaft of a starter generator. To do this, the hub 4th in the middle section 5 an internal thread (not shown) and an internal multi-tooth on the front end section remote from the generator 6th as an engagement contour for the screwdriver. The bearing of the pulley 2 on the hub 4th takes place at the generator-side end radially and axially by means of a roller bearing 7th and at the end remote from the generator radially by means of a plain bearing 8th . The roller bearing 7th is a single row ball bearing sealed on both sides. The plain bearing 8th is a slotted radial bearing ring made of polyamide that is attached to the inner circumference of the pulley 2 is in direct sliding contact. The pulley 4th has a circumferential groove at the end remote from the generator 9 into which after screwing the pulley decoupler 1 a protective cap on the generator shaft 10 is snapped.

The one for the function of the pulley decoupler 1 essential components are a decoupling spring 11 and a loop tape that acts as a barrier 12th . The winding body of the decoupling spring designed as a helical torsion spring 11 and the loop tape 12th extend in and here concentrically to the axial direction of the pulley decoupler 1 , in this first embodiment the decoupler spring 11 the loop tape 12th encloses. The winding body of the loop tape is in the locked state 12th constricted and is located with its inner circumference in torque-transmitting static friction contact with frictional contact partners of the pulley 2 and the hub 4th . The frictional contact partner is the outer jacket 13th a cylindrical protrusion 14th the pulley 2 one hand and an outer jacket 15th the hub 4th on the other hand.

As is the case with the 4th and 5 emerges, the decoupler spring lies 11 with legless spring ends 16 and 17th on a spring plate 18th the pulley 2 one hand and a spring plate 19th the hub 4th on the other hand. Both spring plates 18th , 19th rise axially in a ramp, with the spring ends 16 , 17th on the front side between the spring plate due to the axial ramp shape 18th , 19th formed levels 20th and 21 are clamped. The loop tape 12th is in the drive torque flow between the pulley 2 and the hub 4th parallel to the decoupler spring 11 switched and has loop ends 22nd and 23 in the axial direction of the pulley decoupler 1 are angled and form-fitting in recesses 24 and 25th the pulley 2 or the hub 4th intervention. With both recesses 24 , 25th it is a matter of pass-throughs in the spring plates 18th , 19 at the bottom of the respective step 20th , 21 , the hub-side recess 25th also in 1 is visible.

Due to the engagement of the loop tape ends 22nd , 23 into the recesses 24 , 25th the form fit acts in the present case in both relative directions of rotation of the pulley 2 to hub 4th so that the loop tape 12th over the loop ends 22nd , 23 is twisted both in the (locking) looping direction and thereby tied together and is also twisted counter to the looping direction and thereby widened in diameter. The pairs of forces generating the associated locking torque or opening torque are shown in 3 made clear, with each at the looping tape ends 22nd , 23 The pair of forces drawn in with black arrows generates the locking torque, and the pair of forces directed in the opposite direction and drawn in with white arrows generates the opening torque.

In the unloaded state is the inner diameter of the loop tape 12th larger than the outer diameter of the cylindrical projection 14th and the outer diameter of the outer jacket 15th to the noose 12th to be able to mount axially low-force via its friction contact partner. The extensive relative positioning of the loop tape ends 22nd , 23 , the recesses 24 , 25th , the steps 20th , 21 and the spring ends 16 , 17th is such that the mounted loop tape 12th is under bias in the blocking direction in order to reduce the radial play with respect to the frictional contact partners and, if necessary. to eliminate. In response to this pre-tensioning, the loop tape tensions 12th the steps 20th , 21 against the spring ends 16 , 17th when there is no external torque on the pulley decoupler 1 works.

The associated torques are in 6th shown schematically, the solid line the torque of the decoupler spring 11 and the dashed line is the torque of the sling 12th each depending on the relative angle of rotation of the pulley 2 to hub 4th show. The bias of the loop tape acting in the reverse direction 12th can be recognized by the offset of the torques in relation to the coordinate origin and In the event of a negative relative rotation, the locking effect of the loop tape begins essentially immediately 12th when the starter generator starts driving in the transition to electric motor operation. The torque curve of the loop tape, which drops steeply into the negative 12th is characteristic of its locking effect, in which the pulley 2 torsionally rigid against the hub 4th is looped. The decoupler spring 11 is torque-free in this operating mode.

The pulley decoupler is located when the starter generator is driven 1 positive relative angle of rotation in the operating range. This increases the torque of the decoupling spring 11 due to its relatively high rigidity, it is steeper than the loop band, which also widens in the opening direction 12th .

In the case of alternative designs not shown, the form fit between the belt pulley, hub and loop tape can have a circumferentially unidirectional effect. If, on the one hand, the unloaded loop tape - as in the illustrated embodiment - is mounted with radial play in relation to the frictional contact partners, then the (white) force couple acting in the opening direction can according to FIG 3 omitted. Because in this case the risk of uncontrolled locking of the loop strap is small. If, on the other hand, the unloaded loop belt is mounted with little or, in particular, no radial play with respect to the frictional contact partners, then the (black) force couple acting in the closing direction can according to FIG 3 omitted. Because in this case the loop tape already comes into locking engagement through the frictional contact, so that the bias of the loop tape in the closing direction can be dispensed with.

1. 1.) Der Startergenerator befindet sich im generatorischen Betrieb und wird folglich vom Riemen in der Drehrichtung gemäß 1 angetrieben. Dabei wird das Antriebsmoment des Riemens via Außenmantel 3 der Riemenscheibe 2 - Stufe 20 des Federtellers 18 der Riemenscheibe 2 - Federende 16 der Entkopplerfeder 11 - Entkopplerfeder 11 - Federende 17 der Entkopplerfeder 11 - Stufe 21 des Federtellers 19 der Nabe 4 - Nabe 4 auf die Generatorwelle übertragen. Die Elastizität der Entkopplerfeder 11 kompensiert die Übertragung der Drehschwingungen des Riemens auf die Generatorwelle. Bei negativen Relativdrehwinkeln von Riemenscheibe 2 zu Nabe 4 wird ein Sperren infolge eines unkontrollierten Reibeingriffs des Schlingbands 12 durch dessen formschlüssig erzeugte Aufweitung gegenüber dessen Reibkontaktpartnern verhindert.
2. 2.) Der Startergenerator befindet sich im elektromotorischen Betrieb und treibt folglich den Riemen ebenfalls in der Drehrichtung gemäß 1 an. Dabei wird das Antriebsmoment der Generatorwelle via Nabe 4 - Außenmantel 15 der Nabe 4 - Innenumfang des sperrenden Schlingbands 12 - zylindrischer Vorsprung 14 der Riemenscheibe 2 - Außenmantel 3 der Riemenscheibe 2 auf den Riemen übertragen.

To the functionality of the pulley decoupler:

1. 1.) The starter generator is in generator mode and is consequently driven by the belt in the direction of rotation according to 1 driven. The drive torque of the belt is supplied via the outer jacket 3 the pulley 2 - Step 20th of the spring plate 18th the pulley 2 - end of the spring 16 the decoupler spring 11 - Decoupling spring 11 - end of the spring 17th the decoupler spring 11 - Step 21 of the spring plate 19th the hub 4th - hub 4th transferred to the generator shaft. The elasticity of the decoupler spring 11 compensates for the transmission of the belt's torsional vibrations to the generator shaft. With negative relative rotation angles of the pulley 2 to hub 4th becomes a blocking as a result of an uncontrolled frictional engagement of the loop tape 12th prevented by its positively generated expansion towards its frictional contact partners.
2. 2.) The starter generator is in the electric motor mode and consequently also drives the belt in the direction of rotation according to 1 on. The drive torque of the generator shaft is supplied via the hub 4th - outer sheath 15th the hub 4th - Inner circumference of the locking loop tape 12th - cylindrical projection 14th the pulley 2 - outer sheath 3 the pulley 2 transferred to the belt.

7th shows the second embodiment of a pulley decoupler 1 'according to the invention. This differs from the previously explained pulley decoupler with otherwise the same functionality 1 initially by the radially interchanged arrangement of loop tape 12 'and decoupling spring 11', which in this case is enclosed by loop tape 12 '. The winding directions of loop tape are accordingly 12th , 12 'and decoupling spring 11 , 11 'in the first pulley decoupler 1 same and opposite in the case of the second pulley decoupler 1 '. In the locked state, the wound body of the loop tape 12 'is widened and its outer circumference is in static friction contact with the inner jacket that transmits torque 26th a sleeve pressed into the pulley 2 ' 27 on the one hand and with the inner jacket 28 a cylindrical protrusion 29 the hub 4 'on the other hand. The sleeve 27 simplifies the production of the belt pulley 2 ', which is accessible to a low-cost turning operation with an essentially constant inner diameter.

Another difference is the non-cylindrical, bulbous shape of the loop tape 12 ', the winding body of which has a central section 30' which has a larger diameter than the loop tape ends 22 ', 23'. The largest diameter is located at the axial parting line between the projection 29 the hub 4 'and the sleeve 27 so that the radial play between these frictional contact partners and the non-blocking loop tape 12 'increases towards the loop tape ends 22', 23 ', in the present case from about 0.2 mm to 1 mm. This has the effect that the blocking effect of the frictional contact emanates from the middle section 30 'of the loop tape 12' and increases as the loop tape 12 'gradually widens up to the loop tape ends 22', 23 '. The axially changing radial play between the looping belt 12 'and its frictional contact partners makes it possible to influence the torque curve when the locking effect of the looping belt 12' begins so that the pulley decoupler 1 'with a more or less large torque gradient "hard" or "gently" in overrides the locked operating state. The torque characteristics adapted in this way can be used with the first pulley decoupler 1 realize as well. In the case of cylindrical frictional contact partners, this would be the loop tape 12th in its middle section 30th constricted in diameter.

List of reference symbols

1

Pulley decoupler

2

Pulley

3

Outer jacket of the pulley

4th

hub

5

Central section of the hub

6th

Internal serration

7th

roller bearing

8th

bearings

9

Circumferential groove

10

protective cap

11

Decoupling spring

12th

Loop tape

13th

Outer jacket (cylindrical projection of the pulley)

14th

cylindrical projection of the pulley

15th

Outer jacket of the hub

16

Spring end (on the pulley side)

17th

Spring end (on the hub side)

18th

Spring plate (on the part of the belt pulley)

19th

Spring plate (on the hub side)

20th

Step (on the pulley side)

21

Stage (on the part of the hub)

22nd

Loop strap end (on the side of the belt pulley)

23

Loop end (on the hub side)

24

Recess (on the side of the pulley)

25th

Recess (on the hub side)

26th

Inner jacket of the sleeve

27

Sleeve

28

Inner jacket (cylindrical projection)

29

cylindrical projection

30th

middle section

Claims (8)

Belt pulley decoupler (1, 1 ') for the transmission of drive torque between the belt of a starter-generator belt drive and the starter generator, comprising: - a belt pulley (2), - a hub (4, 4') to be attached to the generator shaft of the starter generator, - a decoupler spring ( 11, 11 '), which transfers the drive torque of the belt from the belt pulley (2) to the hub (4, 4') when the starter generator is driven, - and a lock that transfers the drive torque of the generator shaft from the hub (4, 4 ') to the belt pulley (2), characterized in that the lock is formed by a loop band (12, 12') which in the drive torque flow between the belt pulley (2) and the hub (4, 4 ') parallel to the decoupler spring (11, 11 ') and when the starter generator is driving, the belt pulley (2) loops against the hub (4, 4') in a torsionally rigid manner. Pulley decoupler (1, 1 ') according to Claim 1 , characterized in that the loop band (12, 12 ') is in engagement with the belt pulley (2) on the one hand and the hub (4, 4') on the other hand via a form fit of the loop band ends (22, 22 ', 23, 23'). Pulley decoupler (1, 1 ') according to Claim 2 , characterized in that the loop strap (12, 12 ') has angled loop strap ends (22, 22', 23, 23 ') in the axial direction of the pulley decoupler (1, 1') which form-fit in recesses (24, 25) of the belt pulley ( 2) and the hub (4, 4 ') engage. Pulley decoupler (1, 1 ') according to Claim 2 or 3 , characterized in that the loop belt (12, 12 ') with the belt pulley (2) and the hub (4, 4') is in engagement such that the belt pulley (2) when the starter generator is driven, the loop belt (12, 12 ') twisted against its looping direction. Pulley decoupler (1, 1 ') according to one of the Claims 2 until 4th , characterized in that the loop tape (12, 12 ') twisted over the form fit of the loop tape ends (22, 22', 23, 23 ') both in the opposite direction and in the direction of the loop. Pulley decoupler (1, 1 ') according to one of the Claims 2 until 5 , characterized in that the loop tape (12, 12 ') is mounted twisted in the pulley decoupler (1, 1') over the form fit of the loop tape ends (22, 22 ', 23, 23') with pretension in the looping direction. Pulley decoupler (1, 1 ') according to one of the preceding claims, characterized in that the decoupler spring (11, 11') is a helical torsion spring with legless spring ends (16, 17) which extends in the axial direction of the pulley decoupler (1, 1 ') when the starter generator is driven, the drive torque from stage (20) is axially ramp-shaped the rising spring plate (18) of the belt pulley (2) is transferred to the step (21) of an axially ramp-shaped rising spring plate (19) of the hub (4, 4 '). Pulley decoupler (1 ') Claim 7 , characterized in that the loop tape (12 ') in a central section which loops against the pulley (2) and against the hub (4') has a different diameter than the loop tape ends (22 ', 23'), the The diameter of the middle section is either a.) Larger if the loop tape (12 ') surrounds the decoupler spring (11'), or b.) Is smaller if the decoupler spring surrounds the loop tape.

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