DE19919449A1 - Automotive pulley disc with overload protection device and damping mechanism - Google Patents

Abstract

A drive pulley assembly (1) for use especially in association with chain or belt-driven automotive applications has an input section and an output section linked by an overload protection device and damping mechanism.

Description

The invention relates to a drive pulley for a belt or Chain drive, in particular for driving auxiliary units Internal combustion engine, which is characterized by a special design and Mode of operation according to the present registration documents distinguished.

Furthermore, the invention relates to a drive pulley for a belt or Chain drive, in particular for driving auxiliary units Internal combustion engine.

The present invention was based on the task of such pulleys improve, especially with regard to their function and service life. The drive pulley according to the invention is intended for optimal operation of Auxiliary units such as fans, servo pumps, air conditioning compressors, etc. from Enable internal combustion engines in motor vehicles, namely via the entire during the operation of an internal combustion engine or one  Motor vehicle occurring speed range, that means over the entire speed range from at least idle speed to the permissible Maximum engine speed. Furthermore, the Design of the drive pulley according to the invention for a given Design of a chain or pulley the possible use of this Discs for chain or belt drives with different Vibration behavior may be possible. In addition, the pulley or Drive pulley can be manufactured in a particularly simple and economical manner and are characterized by the smallest possible space requirement.

This object is achieved according to the invention in that the drive pulley is carried out in accordance with the registration documents, or in particular has an overload protection, as set out for example in claim 2 is.

By integrating overload protection, the entire Belt drive by blocking, for example one of them driven compressor can be reliably prevented. Such a drive pulley can the previously used clutches mostly consisted of magnetic couplings, replace, so that the use of permanently driven air conditioning compressors is possible. In principle, this can Drive pulley can be used on all other auxiliary units.  

In a drive pulley according to the invention, it can be advantageous if A damping device is provided between the input part and the output part is, it may be useful if the damping device in Is effective circumferential direction and has energy storage. Furthermore, it can be advantageous if the input part and output part of the drive pulley to each other are rotatably mounted, the rotatability against the action of Damping device, the energy storage also effective in the axial direction may have, may be limited in angle.

A drive pulley according to the invention can advantageously be a Identify damping device with a ramp mechanism, it it is possible to interact with the ramp mechanism with rolling elements to let.

It can be an advantage if, after exceeding a certain limit Angle of rotation between the input part and the output part not the rolling elements interact more with the ramp mechanism, where it turns out to be can prove expedient, the rolling elements after exceeding one certain angle of rotation between the input part and output part in a to bring such position that they are no longer using the ramp mechanism  can cooperate, causing the relative rotation between the input part and output part is unlimited.

It can be particularly advantageous for a drive pulley according to the invention if the overload protection is formed by a slip clutch, the Slipping clutch from an energy accumulator acting in the axial direction can be acted upon. The axially effective energy store required for this can be formed by a plate spring.

The hub part of a drive pulley according to the invention can be made of plastic and / or be made of steel. Of particular advantage for one Drive pulley according to the invention may be when the energy accumulator in Are arranged or effective circumferential direction, the Energy storage, for example, by coil springs or by Spiral springs can be formed, the latter being the Invention of overload protection can be formed by driving lugs the coil springs from these interacting grooves.

In general, it can be advantageous to use overload protection To form a slip clutch, the slip angle dependent slip torque causes. Furthermore, it can be useful if input and / or  Output part of the damping device at least partially made of plastic is / are formed.

It can be particularly advantageous in a drive pulley according to the invention prove if the force accumulators effective in the circumferential direction are large Have length / diameter ratio, these being at least approximately can be pre-curved to their installation radius.

In general, it may prove expedient to use one according to the invention Drive pulley via a bearing, in particular a roller bearing, on a housing supported rotatably.

A drive pulley according to the invention can be radially outer, axially itself extending and profiling for the endless drive means, such as belts or Own chain, exhibiting area.

A drive pulley according to the invention can advantageously be used for driving an auxiliary unit of an internal combustion engine, for example one Air conditioning compressor, which can be permanently driven, serve.

In general, it can be advantageous if a drive pulley according to the invention contains a chamber which can be at least partially filled with viscous medium.  

Furthermore, it can be advantageous if between the input part and the output part a friction device for generating hysteresis is effective.

Another advantageous embodiment of a drive pulley according to the invention may include a slip clutch having a cam friction ring having.

Further design options and advantages of the present invention result from the claims and the description and the figures.

Some exemplary embodiments of the invention will be explained with reference to FIGS. 1 to 20.

In Figs. 1 and 2, a drive pulley is shown, which damps rotary oscillations characterized in that loaded in the axial direction of balls run up a ramp and thereby create a torsion characteristic. The overload protection is achieved in that the balls "snap", ie leave the area of the ramps and then fall into bores, so that the overload clutch can no longer transmit torque, and destruction of the belt drive when the compressor is blocked is reliably prevented. Fig. 1 shows a section through such a drive pulley, while Fig. 2 shows a development that shows on an enlarged scale the ball / ramp mechanism and one of the holes into which the balls fall when the overload protection takes effect.

Fig. 3 shows a section through a differently constructed drive pulley, Fig. 4 shows a sectional view according to the arrows IV of Fig. 3.

FIGS. 5 and 6 show a hub part, which is manufactured using plastic, while Fig. 7 illustrates a manufactured steel hub part.

In such an embodiment of a drive pulley, the damping takes place via steel compression springs, which are arranged in a plastic cage, the Force transmission into the compressor via a combined steel / plastic hub or a steel hub. The overload protection is here by a Slipping clutch realized, the slip torque depending on the spring force of the axially effective disc spring and the coefficient of friction between the drive pulley and the damper input part is determined.

In FIG. 8, a drive pulley is shown, in which the damping is effected by coil springs. FIGS. 9 and 10 each show a sectional view of the coil spring, FIG. 10 showing the unloaded state and FIG. 9 the tensioned state. With such a construction, the overload function is triggered in that the outer driving lugs disengage or disengage from the grooves in the outer part, and thus prevent the rotary movement from continuing.

FIGS. 11 and 12 show sections of a further embodiment of a drive disc, the hub and the hub flange are made entirely of plastic. The overload protection is implemented here using balls that are preloaded via a plate spring and are supported in calottes on the cage. This means that the torque is transmitted without slip via the overload clutch. In the event of an overload, the balls in the retainer cage move outwards in the bore and thus reach a track without spherical caps, which interrupts the torque transmission. An advantage of this embodiment is a relatively low noise level.

Fig. 13 shows a drive pulley to which the features of the overload function can be transferred, which drive pulley includes a damper with arc springs and is designed in a similar manner to that described in DE-OS 196 52 730, the disclosure content of which in the the present application must be considered in an integrated manner

The drive pulley shown in FIG. 14 essentially corresponds to that shown in FIGS. 3 to 7, except for the difference which is shown in FIG. 15 as an enlarged section of the area XV. The friction ring made of plastic there has axially protruding cams that wear out faster when the slip clutch slips, ie in the event of an overload, than would be the case with a "full" friction ring. Thus, the plate spring is increasingly relieved, and the risk of wear on other parts is at least significantly reduced.

FIG. 16 shows a section through a further embodiment of a drive pulley according to the invention, FIG. 17 showing a sectional view according to arrows XVII in FIG. 16.

A further embodiment of a drive pulley according to the invention is shown in the section according to FIG. 18 and the sectional view in FIG. 19 according to the arrows XIX in FIG. 18.

Another embodiment of a drive pulley according to the invention is shown in section according to FIG. 20.

In the embodiments according to FIGS. 16 to 20, the overload protection function is carried out by balls which are partially guided on one side or on both sides in bores or spherical caps and derive the torque to be transmitted to the auxiliary unit via a guide element. The balls are preloaded in the bores or spherical caps by means of a plate spring or a similarly acting energy accumulator and therefore do not allow any relative rotation in normal operation, with the exception of the play of the balls relative to the guide element. In such an embodiment, one or more balls can be arranged axially next to one another. The use of two balls axially next to each other reduces the frictional forces and thereby reduces the influence of friction. In the event of an overload, the balls move out of the holes or spherical caps and the drive pulley, which is mounted on a separate bearing element, can rotate freely. In the event of an overload, the balls can slide continuously over the bores or over the calottes or, for example, in order to avoid or at least reduce noise, be moved out of the circular orbit. Furthermore, there is the possibility of switching off the force accumulator acting in the axial direction, shown here in the form of a plate spring, which is used to preload the balls, in the event of an overload. This can be done for example by a snap spring or over-center spring in the form of a bistable spring. Furthermore, the energy accumulator can be axially relaxed or also shifted, for example via a ramp mechanism, as a result of which the pretensioning force on the balls is reduced or canceled. The embodiments shown in these figures can also be represented with or without friction damping, wherein the friction damping can also have a separate plate spring. Damping or vibration isolation in the drive pulley can be effected, for example, by steel compression springs guided in sheet metal parts, with the force being able to be transmitted via a steel or sintered hub.

To achieve an overload function according to the invention is also a Arrangement with a detonator possible when a Overload torque is ignited electrically and with their energy z. Legs Claw clutch can be opened.

All versions can be "dry" or at least partially filled with a viscous medium. For the function of the Pulley or drive pulley according to the invention it is necessary that at When the overload torque is reached, the drive pulley spins the shaft must be guaranteed during later re-engagement or a subsequent torque transmission between the drive pulley and the shaft is no longer required in all cases.

In addition, it is possible, as shown for example in FIG. 3, to equip all embodiments with a protective cap against the escape of viscous medium or against the ingress of splash water and dirt or the like.

For the following explanation of the invention, a traction sheave assumed the drive is via a belt drive, and the drive pulley transmits the torque via its hub to a shaft connected to it. Such pulleys are used to drive a Auxiliary unit of an internal combustion engine is provided. Such a thing Auxiliary unit is, for example, an air conditioning compressor, i.e. a compressor for the refrigerant of an air conditioning system in a motor vehicle. Such Air conditioning compressors are mostly connected to their electromagnetic clutch Drive pulley, which interacts with the belt drive, connected. It will however, permanently driven air conditioning compressors are also provided, in which the electromagnetic clutch is omitted, so that the air conditioning compressor at Operation of the internal combustion engine is running continuously. With such In the event of failure, air conditioning compressors can be of components of the air conditioning compressor, the entire belt drive through the blocking drive disk of the air conditioning compressor affected or be destroyed. This is said to be an overload protection prevent the present invention.

It goes without saying that such a drive pulley also with one Torque flow can be used in which the torque of one Shaft on the hub of the drive pulley and from there to the output side  Part of the pulley is guided with a drive belt or Drive chain is connected.

The drive pulley 1 shown in Fig. 1 comprises an input portion 2 and an output part 3, which is for example in the form of an air compressor, is connected via a hub 4 to the shaft 5 of a driven auxiliary unit, not shown here. The input part 2 has a substantially U-shaped cross-section, one of which has an axially extending region 6 with profiles 7 which cooperate with the endless drive means. Here, the endless drive means, not shown, is formed by a belt.

This axially directed region 6 is arranged radially on the outside on the wall 8 of the input part 2 , which receives or is connected to a further axial section 9 radially on the inside, which encloses the bearing 10 . This bearing 10 is supported axially on a shoulder 11 of the axial section 9 and, on the other hand, is accommodated on a support region 12 of the housing 13 of the unit to be driven, which is not shown in detail. On the housing side, the bearing 10 is axially fixed via the contact area 14 .

Between the input part 2 and the output part 3 of the drive pulley 1 , an overload protection 15 is provided, which essentially consists of two annular elements 16 , 17 , between which balls 18 are arranged and axially loaded by means of at least one axially acting energy accumulator 19 , here in the form of coil springs . The annular element 16 is non-rotatably connected to the axial section 9 of the input part 2 via profiles 20 , while the annular element 17 is non-rotatably connected to the axially directed wall 22 of the output part 3 via profiles 21 . The axially directed wall 22 is connected on the one hand to the wall 23 and on the other hand to the hub disk 24 , the wall 23 and at least part of the axially directed wall 22 in the area 6 extending through the axially extending area, the wall 8 and the axial section 9 of the input part 2 immerse the space formed.

The hub disk 24 is connected radially on the inside to the hub 4 , which in the present example is made of plastic. The hub 4 and thus the entire drive pulley 1 are connected to the shaft 5 of the unit to be driven via a fastening element 25 , here in the form of a screw.

The overload protection 15 is arranged in the space 26 formed by parts of the input part 2 and the output part 3 . The energy accumulators 19 are supported on the one hand on the wall 23 of the output part 3 , and on the other hand act on the annular element 17 with an axial force, as a result of which the balls 18 , as can also be seen in FIG. 2, are pressed into depressions 27 and 28 which are in the annular elements 16 and 17 are provided. As can be seen from the development according to FIG. 2, the depressions 27 and 28 each have ramps 29 and 30 on a side located in the circumferential direction.

When the input part 2 is rotated or driven counterclockwise, a force in the direction of arrow 31 is applied to the annular element 16 via the profiling 20 . This driving force counteracts the force resulting from the resistance of the unit to be driven in the direction of arrow 32 , the annular element 17 and with it, via the profiles 21, the output part 3 being driven in the circumferential direction for as long as the rotational resistance of the unit to be driven is not certain dimension exceeds.

In the event of a defect in the unit to be driven and a resultant increased torsional resistance, or when the unit is at a standstill with the engine running and therefore driven drive pulley 1 , the ring-shaped element 17 is prevented from rotating while the ring-shaped element 16 continues to move in the direction of the arrow 31 twisted or moved. Thus, the ring-shaped elements 16 and 17 move relative to one another, as a result of which the balls 18 are pushed onto the ramps 29 and 30 and thus tension the axially acting energy accumulator 19 , since the ring-shaped element is pushed towards the wall 8 in the direction of the arrow 33 . If the axial force resulting from the rotation of the annular elements 16 and 17 relative to one another in the direction of arrow 33 exceeds the spring force of the axially acting energy accumulator 19 , the annular elements 16 and 17 are pushed apart so far that the balls 18 are moved out of their recesses 27 , 28 and can dive into a further recess 34 . This recess 34 in the annular element 16 is designed so that the ball 18 can immerse it axially so far that practically no force can be transmitted between the annular elements 16 and 17 , whereby the input part 2 is separated from the output part 3 . In this way, the defective unit to be driven is separated from the drive means, for example a V-ribbed belt, whereby the entire belt drive is protected. It is no longer possible to drive the unit to be driven via shaft 5 ; the torque transmission is interrupted permanently.

As in the example shown, the hub 4 can be formed from plastic, which may result in advantages in terms of vibration technology. However, it is readily possible to form the hub 4 from metal, wherein the hub disk 24 and the hub 4 can also be made in one piece. The ring-shaped elements 16 and 17 can be produced both from a metallic material and from plastic, the latter having the advantage of enabling cost-effective production, for example when using an injection molding process.

In an embodiment of a drive pulley 101 according to FIGS. 3 to 7, the overload protection 115 between the input part 102 and output part 103 is formed by a slip clutch 135 . The slip clutch 135 comprises a slip element 136 and an axially active energy accumulator 119 . The energy accumulator 119 , which is formed here by a plate spring, is supported on the wall 108 and acts on the sliding element 136 with an axial force which presses it against the wall 137 . If necessary, a friction disk 138 can be arranged between the slide element 136 and the wall 137 , which can either be connected to the wall 137 or to the slide element 136 or can also be arranged rotatably with respect to both. In the same way, a friction disk 139 can be arranged on the axially opposite side of the sliding element 136 , which is acted upon by the force accumulator 119 acting in the axial direction with the interposition of the support disk 140 . In this manner, the slip element is held clamped in the input part 102 136 and is rotatable with respect thereto only with a particular by the friction pairings and the axial force of the energy accumulator 119 transmissible torque from the input part 102nd

In the circumferential direction, effective energy stores 141 in the form of helical springs are provided in the slide element 136 and are part of the damping device 142 . The power-assisted memory 141 in the circumferential direction on the one hand to supply regions 143 of the slide member 136, and act on the other hand in the axial direction facing arms 144 of the hub disc 124th As can be seen in particular from FIG. 4, the axially directed arms 144 protrude into recesses 145 of the slide element 136 . These recesses 145 allow the axially pointing arms 144 and thus the output part 103 to be rotated relative to the sliding element 136 . When the slide element 136 and the hub disk 124 are twisted, the force accumulators 141 are compressed and thus contribute to vibration damping or vibration isolation. The recesses 145 have a greater extent in the circumferential direction than the axially directed arms 144 , and thus define the possible angle of rotation between the hub disk 124 and the slide element 136 . After the play in the circumferential direction has been used up, the axially directed arms abut the ends of the cutouts and thus cause the sliding element 136 to rotate relative to the input part 102 , the torque that can be transmitted between these two parts being determined by the sliding clutch 135 .

A friction hysteresis generated by the friction device 146 is connected in parallel with the action of the energy stores 141 . This serves to dampen vibrations and consists of an axially effective spring element which is axially clamped between the input part 102 and the output part 103 and in the illustrated embodiment is axially supported on the hub disk 124 with the interposition of a friction ring 147 . Furthermore, the drive pulley 101 has a cover 148 which, in addition to its function as protection against contamination, can also help to reduce the noise emitted by the drive pulley.

In FIGS. 5 and 6, the output portion 103 is shown as an individual part, wherein the hub plate 124 made of metal and the hub of the hub body 104 are made of plastic or in this embodiment.

The drive pulley 101 shown in FIG. 7, unlike the drive pulley shown in FIG. 3, has no cover 148 . In addition, in this example, the output part 103 is formed by a hub disk 124 and a hub 104 likewise made of metal.

In Figs. 8 to 10, a drive pulley 201 is shown with effective power saving in the circumferential direction 241, which are formed in this embodiment by four interconnected Laid spiral springs. The coil springs 241 arranged between the input part 202 and the output part 203 are arranged with one end in recesses 249 of the input part 202 and in recesses 250 of the output part 203 . The depressions or grooves 250 are provided with essentially straight flanks, whereas the depressions 249 have bevels 251 which cooperate with the correspondingly designed ends of the spiral springs 241 .

In the event of a rotation between the input part 202 and the output part 203 , each of the spiral springs 241 is either contracted further or expanded, depending on the direction of relative rotation. This change in shape of the coil springs 241 and the associated spring action or restoring action takes place until a predetermined torque limit is reached. When this limit torque is reached, the spring ends interacting with the input part 202 in the present example slide off on the bevels 251 , so that the spring ends are pressed out of the recesses 249 and the positive engagement present there is canceled. In this state, input part 202 and output part 203 can be moved practically freely with respect to one another and are thus “decoupled” from one another. If the torque between the input part 202 and the output part 203 falls back below the value of the limit torque, the spring ends can "catch" again in the recesses 249 , as a result of which the input part 202 and the output part 203 are coupled to one another again. In this state, it is possible to drive the auxiliary unit coupled to the belt pulley or drive pulley 201 . In such an embodiment, the limit torque results, for example, from the centrifugal force acting on the spiral springs 241 , which in turn is dependent on the speed, the material pairing that determines the coefficient of friction, and the design of the bevels 251 .

In the drive pulley 301 shown in FIGS . 11 and 12, balls 318 are arranged between the slide element 336 and the support ring 352, which balls are pushed into dome-shaped recesses 327 , 328 of the slide element 336 and the support ring 352 by the axially effective energy store 319 , which is designed here as a plate spring will. Between the slide element 336 and the hub disk 324 , effective energy stores 341 are provided in the circumferential direction, which in turn serve to isolate the vibrations.

When a limit torque is exceeded, the balls 318 are pressed out of their dome-like depressions 327 and 328 against the action of the plate spring 319 and are displaced radially outward into the recesses 353 under the influence of centrifugal force. In the radial region of this recess 353 , a smooth surface without calottes is provided in the support ring 352 , so that the balls 318 can roll between the slide element 336 and the support ring 352 . The overload protection 315 is practically designed here as a "ball-bearing slip clutch". In the present example, both the slide element 336 and the support ring 352 and the output part 303 are formed from plastic, the energy stores 341 , which are designed as helical springs, which are effective in the circumferential direction being accommodated in corresponding recesses in the slide element 336 and the output part 303 .

Fig. 13 shows the basic structure of a drive pulley to which the present inventive concepts are applicable.

The drive pulley 401 shown in FIGS. 14 and 15 essentially corresponds to the embodiment shown in FIGS. 3 to 7, but here the friction ring 438 has a special configuration. The friction ring 438 is subdivided into the friction ring main body 454 , which is of essentially circular design, and in an area with axially protruding cams 455 , which are formed in one piece with the friction ring main body 454 . The friction ring 438 shown here is made of plastic and can be produced economically, for example, by an injection molding process. The friction ring 438 is pressed against the wall 437 by the force of the axially active energy accumulator 419 , which in turn is designed here as a plate spring. In the event of a relative rotation between the friction ring 438 and the wall 437 , only the cams 455 are supported on the wall 437 and thus reduce the sliding surface. Here, too, the overload protection 415 comes into operation when the slip clutch 435 begins to slip above a certain limit torque. During this relative movement between the friction ring 438 and the wall 437 , wear first occurs on the cams 455 , as a result of which the plate spring 419 relaxes with increasing wear. With further increasing wear, the cams 455 are ground down until the friction ring base body 454 comes into contact with the wall 437 and the friction surface thus increases again. By relaxing the axially acting energy accumulator 419 , however, the frictional force caused by it is already reduced accordingly.

In Figs. 16 and 17, a further drive wheel 501 according to the invention is shown. The input part 502 and the output part 503 are in turn coupled to one another in a rotationally elastic manner via force accumulators 541 effective in the circumferential direction, which in the present case are formed by coil springs. The friction hysteresis generated by the friction device 546 is connected in parallel with the effect of this energy store 541 . In this embodiment, the overload protection 515 is formed by pairs of balls distributed over the circumference and containing two axially adjacent balls 518 , which are clamped between the annular element 516 and the wall 537 under the influence of the axially acting energy accumulator 519 . For this purpose, the annular element 516 has recesses or bores 528 and the wall 515 has recesses or bores 527 . The balls 518 are guided through the element 536 between the annular element 516 and the wall 537 .

When a limit torque is exceeded, the overload protection comes into operation in that the wall 537 and the annular element 516 are rotated relative to one another, as a result of which the balls are pressed out of the recesses 527 and 528 against the pretensioning force of the axially active force accumulator 519 , so that the drive part or Input part 502 and the output part 503 are decoupled from each other.

The drive pulley 601 shown in FIGS. 18 and 19 is essentially comparable to that shown in FIGS. 16 and 17, wherein the balls 618 do not abut one another directly axially, but are separated from one another by the element 636 . Here, too, the balls 618 are fixed in recesses by the axially active energy store 619 until a certain limit torque is exceeded when the input part 602 and the output part 603 are rotated. After this limit torque has been exceeded, the balls 618 are pressed out of their depressions against the action of the plate spring 619 and the input part 602 and output part 603 are thus separated from one another. The embodiment shown here also has force accumulators 641 which are effective in the circumferential direction and are used for vibration isolation.

The embodiment of a drive pulley 701 according to the invention shown in FIG. 20 in turn comprises, in the circumferential direction, force accumulators 741 which are arranged between the input part 702 and the output part 703 and which serve to isolate the vibrations. For this purpose, the energy accumulators 741 are supported on the one hand on the hub disk 724 , while on the other hand they are supported and received between the side disks 756 and 757 arranged on both sides of the hub disk 724 . Radially outside the energy accumulators, balls 718 are arranged in recesses in the side disks 756 , 757 , which are pressed into the recesses 727 of the wall 737 by the spring force of the axially active energy accumulator 719 and the support disk 740 and thus form the overload protection 715 . When a limit torque is reached during a relative rotation between the input part 702 and the output part 703 , the balls 718 are pushed out of these recesses or bores 727 against the spring force of the plate spring 719 , which in turn decouples the input part 702 from the output part 703 .

The claims submitted with the application are drafted strikes without prejudice for obtaining further patent protection. The  The applicant reserves the right to add more, so far only in the description and / or Drawings to claim disclosed features.

Relationships used in subclaims point to further training the subject of the main claim by the features of the respective towards subclaim; they are not considered a waiver of achieving one independent, objective protection for the characteristics of the back-related To understand subclaims.

However, the subjects of these subclaims also form independent inventions dungen, which is one of the objects of the preceding subclaims have independent design.

The invention is also not based on the exemplary embodiments of the description limits. Rather, numerous changes and modifications are within the scope of the invention Modifications possible, especially such variants, elements and comm combinations and / or materials, for example by combination or Ab conversion of individuals in conjunction with those in the general description and embodiments and the claims described and in the drawing inventions contained features or elements or process steps and are combinable features to a new item or  lead to new process steps or process step sequences, also insofar as they Manufacturing, testing and working procedures concern.

Claims (31)

1. Drive pulley for a belt or chain drive, in particular for driving ancillaries of an internal combustion engine, characterized by its special design and mode of operation in accordance with the present application documents. 2. Drive pulley for a belt or chain drive, especially for the drive of auxiliary units of an internal combustion engine, such as on a shaft Drive shaft of an auxiliary unit, can be fastened and an input part and has an output part, characterized in that between A Overhead protection and output part is provided. 3. drive pulley, in particular according to one of claims 1 or 2, characterized characterized in that a damper between the input part and the output part tion device is provided.   4. Drive pulley, in particular according to claim 3, characterized in that the damping device is effective in the circumferential direction and energy storage having. 5. drive pulley, in particular according to one of claims 1 to 4, characterized characterized in that the input part and the output part can be rotated relative to one another are stored. 6. drive pulley, in particular according to one of claims 1 to 5, characterized characterized in that the damping device effective in the axial direction Has energy storage. 7. drive pulley, in particular according to one of the preceding claims, characterized in that the damping device has a ramp has mechanism 8. drive pulley, in particular according to one of the preceding claims, characterized in that the ramp mechanism with rolling elements cooperates. 9. drive pulley, in particular according to one of the preceding claims, characterized in that after a certain Ver  angle of rotation between the input part and the output part not the rolling elements interact more with the ramp mechanism. 10. drive pulley, in particular according to one of the preceding claims, characterized in that the rolling elements after exceeding a be agreed twist angle between the input part and output part in one such a situation that they are no longer with the ramp can interact and thus the relative rotation between the input part and output part is unlimited. 11. drive pulley, in particular according to one of the preceding claims, characterized in that the overload protection by a slip clutch lung is formed. 12. Drive pulley, in particular according to claim 12, characterized in that the slip clutch of an effective energy store in the axial direction is applied. 13. drive pulley, in particular according to one of the preceding claims, characterized in that the axially active energy store by a Belleville spring is formed.   14. drive pulley, in particular according to one of the preceding claims, characterized in that the hub part is formed from plastic. 15. drive pulley, in particular according to one of the preceding claims, characterized in that the hub part is made of steel. 16. drive pulley, in particular according to one of the preceding claims, characterized in that the energy storage is in the circumferential direction are arranged. 17. Drive pulley, in particular according to one of claims 4, 6 or 16, there characterized in that the energy accumulator gebil by coil springs det. 18. drive pulley, in particular according to one of the preceding claims, characterized in that the energy accumulator is formed by spiral springs are. 19. Drive pulley, in particular according to claim 18, characterized in that the overload protection is formed by driving lugs of the spi Notch ral springs from these interacting grooves.   20. drive pulley, in particular according to one of the preceding claims, characterized in that the overload protection by a slip clutch is formed, which causes a slip torque dependent slip angle. 21. Drive pulley, in particular according to one of the preceding claims, characterized in that the input and / or output part of the damper is at least partially made of plastic. 22. drive pulley, in particular according to one of the preceding claims, characterized in that the effective force in the circumferential direction cher have a large length / diameter ratio. 23. Drive pulley, in particular according to claim 23, characterized in that that the energy storage is at least approximately on their installation radius are crooked. 24. drive pulley, in particular according to one of the preceding claims, characterized in that the drive pulley via a bearing, in particular re a roller bearing is rotatably supported on a housing. 25. drive pulley, in particular according to one of the preceding claims, characterized in that the drive pulley has a radially outer, axial  extending and profiling for the endless drive means, such as Belt or chain, possessing area. 26. Drive pulley, in particular according to one of the preceding claims, characterized in that it is used to drive an auxiliary unit Internal combustion engine is provided. 27. Drive pulley, in particular according to claim 26, characterized in that that the drive pulley is provided for driving an air conditioning compressor. 28 drive pulley, in particular according to claim 27, characterized in that they propose to drive a permanently driven air conditioning compressor is seen. 29. Drive pulley, in particular according to one of the preceding claims, characterized in that it includes a chamber which at least partially fillable with viscous medium. 30. drive pulley, in particular according to one of the preceding claims, characterized in that between the input part and the output part Friction device is effective.   31. drive pulley, in particular according to one of the preceding claims, characterized in that the slip clutch verse one with cams has the friction ring.