DE102019210502B3 - Pulley assembly - Google Patents

Abstract

The invention relates to a belt pulley arrangement with an electric machine (RSG) with an electric machine shaft (1), which can be drivably connected to an internal combustion engine shaft (5) via an internal combustion engine belt drive (RBKM), and via an assembly belt drive (RmKK) with an auxiliary unit, in particular a mechanical air conditioning compressor (mKK), is drivingly connectable, with a switchable pulley (9), which is part of the internal combustion engine belt drive (RBKM), and a non-rotatable belt pulley (11) arranged on the electric machine shaft (1) which is part of the unit belt drive (RmKK), whereby the switchable belt pulley (9) can be coupled to or decoupled from the electric machine shaft (1) to transmit torque via a coupling device depending on different operating modes (MB1, MB2, GB). According to the invention, in a first motor operating mode (MB1) on the clutch device, a power split takes place in which a drive torque generated by the electric machine (RSG) is transferred into a load path (L1) from the electric machine shaft (1) towards the internal combustion engine belt drive (RBKM) and in a load path (L2) from the electric machine shaft (1) in the direction of the unit belt drive (RmKK) is divided. In a second motor operating mode (MB2), a drive torque generated by the electric machine (RSG) is transmitted from the electric machine shaft (1) in a load path (L5) in the direction of the unit belt drive (RmKK) without power split.

Description

The invention relates to a pulley arrangement for an internal combustion engine auxiliary unit, in particular a mechanical air conditioning compressor, according to the preamble of claim 1.

Conventional vehicles have a drive for auxiliary units. Driven by the internal combustion engine, an electric machine and a mechanical air conditioning compressor, among other things, are supplied with power. The introduction of start-stop or hybrid systems, as well as “sailing” operation and the like, greatly reduces the running time of the internal combustion engine and thus the availability of the mechanical air conditioning compressor. If air conditioning is required, there is therefore a so-called “start-stop veto”. In this case, the internal combustion engine must run or be started, although there is no request for vehicle propulsion. Starting the engine simply because there is a need for air conditioning affects the energy balance in the entire vehicle. An alternative is to provide an electrically driven air conditioning compressor instead of a mechanical air conditioning compressor. However, compared to the mechanically driven air conditioning compressor, this has significant disadvantages in terms of procurement costs, component weight and space requirements.

A pulley arrangement has an electric machine with an electric machine shaft on which a pulley, which can be switched via a clutch device, and a non-rotatable pulley are arranged. The switchable pulley can be drivably connected to an internal combustion engine shaft via an internal combustion engine belt drive. In addition, the non-rotatable belt pulley can be connected to an assembly shaft via an assembly belt drive. In a first motor operating mode, the electric machine drives via its electric machine shaft and the internal combustion engine belt drive in a first driving direction of rotation on the internal combustion engine. In this case, an engine start of the internal combustion engine can take place, for example, or a boost operation can take place in which the running internal combustion engine is supported with an additional electromotive torque. Alternatively, in a generator operating mode, the internal combustion engine can drive onto the electric machine in the first drive direction of rotation via its internal combustion engine shaft and the internal combustion engine belt drive. In this case, the vehicle battery connected to the electric machine can be charged and the air conditioning compressor can also be driven.

The electric machine can also operate in an additional operating mode, that is to say a second engine operating mode. In the second motor operating mode, the electric machine can drive onto the auxiliary unit via its electric machine shaft and the unit belt drive, specifically when the internal combustion engine is shut down, that is, drive off onto the auxiliary unit independently of the internal combustion engine.

The implementation of the above first motor mode, the second motor mode and the generator mode is only possible in the prior art with additional actuators that have to be controlled by an external control unit. The provision of such actuators is therefore complex in terms of control technology and requires components and installation space.

From the EP 1 454 043 B1 a variable belt drive for auxiliary units is known. From the DE 197 54 872 A1 a pulley for overrunning clutches with two belts is known. From the DE 10 2013 108 839 A1 a pulley assembly is known.

From the DE 10 2009 016 911 A1 a generic belt-driven generator-starter system for a hybrid vehicle is known. From the DE 10 2008 006 578 A1 a vehicle propulsion system is known.

The object of the invention is to provide a belt pulley arrangement for an internal combustion engine auxiliary unit, in particular a mechanical air conditioning compressor, in which the control effort and the installation space and component requirements are reduced compared to the prior art.

The object is achieved by the features of claim 1. Preferred developments of the invention are disclosed in the subclaims.

According to the invention, actuators that can be controlled externally by means of electronic control devices are dispensed with. Instead, according to the characterizing part of claim 1, the coupling device for the switchable belt pulley has an overrunning clutch and a centrifugal clutch. The overrunning clutch and the centrifugal clutch open or lock automatically in the two engine operating modes as well as in the generator operating mode of the electric machine, that is to say without the influence of, for example, electrical or hydraulic external energy. In this way, especially when the internal combustion engine is at a standstill (that is to say when the internal combustion engine shaft is at a standstill), the electric machine can be the auxiliary unit, in particular a mechanical air conditioning compressor, independent of the internal combustion engine.

In the first engine operating mode, the overrunning clutch can lock in a torque-transmitting manner and the centrifugal clutch can be transmission-free. In the generator operating mode, the overrunning clutch can be transmission-free and lock the centrifugal clutch in a torque-transmitting manner. In the second motor operating mode, both the overrunning clutch and the centrifugal clutch can be transmission-free.

Against this background, in a technical implementation, the torque-transmitting locking function of the overrunning clutch can be activated in the first motor operating mode in a first direction of drive rotation of the electric machine shaft. In the first engine operating mode, the electric machine can either be used to start the engine or to perform a boost function while the internal combustion engine is running. The transmission-free freewheeling function of the freewheel clutch, on the other hand, can be activated when the electric machine is operating in a second driving direction of rotation which is opposite to the first driving direction of rotation.

The torque-transmitting locking function of the centrifugal clutch can be activated in the generator operating mode of the electric machine. In contrast to this, their transmission-free freewheeling function can be activated when the electric machine is operating in the opposite, second driving direction of rotation.

With the above embodiment variant, the electric machine can rotate in the second drive direction of rotation in the second motor operating mode (that is, drive the auxiliary unit when the internal combustion engine shaft is shut down). In the second drive direction of rotation, the freewheel functions are activated both in the overrunning clutch and in the centrifugal clutch, that is, both clutches are free of transmission. The electric machine can therefore drive the auxiliary unit even when the internal combustion engine is shut down.

In a specific embodiment variant, the switchable belt pulley can be arranged on the electric machine shaft with the overrunning clutch being radially interposed. In common practice, the overrunning clutch can have an overrunning clutch on the outside and an overrunning clutch on the inside. Adjustable clamping elements are arranged between the overrunning clutch inside and the overrunning clutch outside. Depending on the direction of rotation of the inside and the outside, the clamping elements can be adjusted into a clamping position or into a release position due to a relative movement.

The centrifugal clutch can have at least one centrifugal force element that can be acted upon by centrifugal force. The centrifugal force element can be displaced between a rest position and a locking position under the action of centrifugal force. In the locked position to which centrifugal force is applied, the centrifugal force element can be in engagement with a mating contour of the electric machine shaft. In contrast, the centrifugal force element can be out of engagement with the mating contour of the electric machine shaft in its rest position.

In an embodiment variant that is advantageous in terms of installation space, the non-rotatable belt pulley and the switchable belt pulley can be arranged axially directly adjacent to one another on the electric machine shaft. With regard to an implementation that is economical in terms of installation space, it is preferred if the non-rotatable belt pulley provides a radially inner installation space. The centrifugal force element of the centrifugal clutch can be positioned in the installation space of the rotationally fixed pulley. The radially inner installation space of the non-rotatable belt pulley can be formed on the side of the non-rotatable belt pulley facing the switchable belt pulley. With regard to the largest possible installation space, this can be formed between a radially outer groove ring, a radially inner hub section and a connecting flange of the rotationally fixed pulley. The connecting flange connects the radially inner hub section with the radially outer groove ring. With this geometry of the non-rotatable belt pulley, the mating contour that interacts with the centrifugal force element can be formed directly on the inner circumference of the ring of grooves of the non-rotatable belt pulley in a space-saving manner.

In a structurally simple embodiment variant, the centrifugal clutch can have a linear guide by means of which the centrifugal element can be linearly adjusted between its rest position and its locking position. To implement the linear guide, the switchable belt pulley can be axially extended in one piece and made of the same material with a support ring. The support ring can be reduced in diameter compared to the switchable belt pulley and, in the assembled position, protrude nested in the installation space of the axially adjacent non-rotatable belt pulley. In the support ring of the switchable belt pulley, at least one radially aligned guide channel can be formed in which the centrifugal force element is guided in a radially adjustable manner.

In a structurally simple development, the guide channel formed in the support ring of the switchable pulley can be axially open on the end face. In the assembled state, the axially open end face of the guide channel can be closed directly by the connecting flange of the rotationally fixed pulley.

In the second engine operating mode, the electric machine drives the auxiliary unit independently of the (shut down) internal combustion engine. In this case, the electric machine shaft rotates together with the non-rotatable belt pulley arranged on it. In contrast, the internal combustion engine belt drive together with the switchable pulley remains shut down, so that a relative rotational movement takes place between the switchable (shut down) pulley and the rotating, non-rotating pulley and the electric machine shaft. In this case, the support ring of the switchable belt pulley can preferably be in sliding contact with the outer circumference of the hub section and with the connecting flange of the rotationally fixed belt pulley or be slightly spaced therefrom.

With regard to perfect functionality, it is preferred if the centrifugal force element is spring-preloaded into its radially inner rest position with a spring. In this case, the centrifugal force element can be in its radially inner (spring-preloaded) rest position in contact with a radial stop formed on the switchable belt pulley. Therefore, in its radially inner rest position, the centrifugal element can be out of sliding contact with the hub portion of the rotationally fixed pulley.

A radial free space can be provided between the support ring of the switchable pulley and the inner circumference of the ring of grooves of the rotationally fixed pulley. When centrifugal force is applied, the centrifugal force element can come into engagement with the counter-contour formed on the inner circumference of the ring of grooves of the non-rotatable belt pulley, using up this radial free space.

It is advantageous in terms of installation space if the spring is arranged in the radial free space between the support ring of the switchable pulley and the inner circumference of the grooved ring of the non-rotatable pulley. The radial free space can be continuously open all the way round (that is, without interruption). In this case, the spring can preferably be an annular spring, which is stretched onto the outer circumference of the support ring of the switchable pulley and / or moves around the support ring outer circumference without interruption.

With a view to positioning the annular spring in the correct position, a circumferential spring groove in which the annular spring is arranged can be formed on the outer circumference of the support ring of the switchable pulley. If the centrifugal force is very high, there may be a risk that the ring spring will lift off radially outward from the outer circumference of the support ring. Against this background, a circumferential (radially inwardly open) spring groove can also be formed on the inner circumference of the ring of grooves of the rotationally fixed pulley, in which the annular spring lifting off the inner circumference of the support ring can be retracted.

Regardless of the concrete structure of the pulley arrangement set out above, a general aspect of the invention is generally directed to a switchable pulley which is arranged on a drive shaft (i.e. in particular the electric machine shaft) and can be coupled to or decoupled from the drive shaft via a coupling device to transmit torque, depending on different modes of operation of the pulley assembly. In a first operating mode (in particular the above-mentioned first motor operating mode) the coupling device couples the drive shaft to the switchable pulley in such a way that a load path L1 is formed from the drive shaft in the direction of the switchable pulley when the drive shaft rotates in a first drive direction of rotation. In a second operating mode (i.e. in particular the generator operating mode) the coupling device couples the drive shaft to the switchable pulley in such a way that when the drive shaft rotates in the first drive direction of rotation, an opposing load path L3 is formed from the switchable pulley into the drive shaft. In a third operating mode (i.e. in particular the second motor operating mode), the coupling device decouples the drive shaft from the switchable pulley, so that when the drive shaft rotates in a second opposite direction of drive rotation, a load path L5 is formed without power split along the drive shaft, and with considerable relief or decoupling of the switchable pulley from the drive shaft.

An exemplary embodiment of the invention is described below with reference to the accompanying figures.

• 1 bis 3 jeweils Ansichten einer als Blockschaltdiagramm angedeuteten Riemenscheibenanordnung in unterschiedlichen Betriebszuständen;
• 4 bis 7 in Schnittdarstellungen die Kupplungseinrichtung mit deaktivierter Fliehkraftkupplung (4 und 5) sowie mit aktivierter Fliehkraftkupplung (6 und 7); und
• 8 ein Federkraft-Drehzahl-Diagramm.

Show it:

• 1 to 3 in each case views of a pulley arrangement indicated as a block diagram in different operating states;
• 4th to 7th in sectional views the clutch device with deactivated centrifugal clutch ( 4th and 5 ) as well as with activated centrifugal clutch ( 6th and 7th ); and
• 8th a spring force-speed diagram.

In the 1 a pulley assembly includes an electric machine RSG on, which is connected to a vehicle battery 14 via an electrical supply line. The electric machine RSG is with an internal combustion engine BKM of a vehicle and a mechanical air conditioning compressor forming the auxiliary unit mKK drive connected. An electric machine shaft 1 the electric machine RSG , an aggregate wave 3 of the air conditioning compressor mKK as well as an internal combustion engine shaft 5 are arranged axially parallel to one another and via an internal combustion engine belt drive R _BKM and via an aggregate belt drive R _mKK connected with each other instinctively. The internal combustion engine belt drive R _BKM points in the 1 one fixed against rotation on the engine shaft 5 seated pulley 7th as well as a switchable pulley 9 on that on the electric machine shaft 1 is arranged. The switchable pulley 9 is by means of a clutch device described later, depending on different operating modes MB1, MB2, GB with the electric machine shaft 1 Can be coupled or decoupled to transmit torque. The aggregate belt drive R _mKK has one on the electric machine shaft 1 arranged, non-rotatable pulley 11 and a pulley on the unit side 13 on.

In the 1 the clutch device is made up of an overrunning clutch K1 and a centrifugal clutch K2. These can be found in the 1 to 3 the illustrated modes of operation MB1, GB, MB2 automatically couple or decouple so that the switching operations can be carried out without external hydraulic or electric actuators. The following are based on the 1 to 3 the operating modes MB1, GB, MB2 described, in which the pulley arrangement can be operated.

In the 1 the pulley arrangement works in the first motor mode MB1, in which the electric machine RSG carries out an engine start or a boost function. In the first motor operating mode MB1 is in the electric machine RSG generates a drive torque. On the clutch device of the switchable pulley 9 there is a power split in which this is done by the electric machine RSG generated drive torque in a load path L1 from the electric machine shaft 1 in the direction of the internal combustion engine belt drive R _BKM and into a load path L2 from the electric machine shaft 1 in the direction of the unit belt drive R _mKK is divided. The electric machine wave 1 the electric machine RSG drives with a first drive direction of rotation A1 (i.e. clockwise rotation) on the engine shaft 5 and on the aggregate shaft 3 from, which is also in the first driving direction of rotation A1 rotate.

In the 2 works the pulley assembly in a generator mode GB, in which one of the internal combustion engine BKM generated drive torque in a load path L3 from the engine shaft 5 via the internal combustion engine belt drive R _BKM to the electric machine shaft 1 and on to the electric machine RSG is transmitted. In addition, there is a power split in the case of the load path L3 a load path L4 branches off from the electric machine shaft 1 via the unit belt drive R _mKK to the air conditioning compressor mKK is led. The internal combustion engine shaft 5 the electric machine RSG drives with the first drive direction of rotation A1 (i.e. clockwise rotation) on the electric machine shaft 1 and on the aggregate shaft 3 from, which is also in the first driving direction of rotation A1 rotate. In the GB generator operating mode, the electric machine is charged RSG connected vehicle battery 14 and at the same time a drive for the air conditioning compressor mKK .

In the 3 the pulley assembly operates in a second motor mode MB2. In the second motor operating mode MB2, a is from the electric machine RSG generated drive torque in a load path L5 without power split from the electric machine shaft 1 in the direction of the unit belt drive R _mKK transfer. The switchable pulley 9 is switched load-free by the clutch device in the second engine operating mode MB2. In contrast to the first motor operating mode MB1 and the generator operating mode GB, the electric machine drives RSG with the opposite second drive direction of rotation A2 (i.e. left turn) on the unit belt drive R _mKK from. The second motor operating mode MB2 takes place when the internal combustion engine is shut down BKM . In this case, the air conditioning compressor mKK , regardless of the internal combustion engine BKM , from the electric machine RSG be supplied with drive power.

To implement the above three operating modes MB1, MB2, GB, the torque-transmitting blocking function is activated in the overrunning clutch K1 in the first motor operating mode MB1. In this case the load path runs L1 ( 1 ) from the electric machine RSG via the locked overrunning clutch K1 and in the first direction of drive rotation A1 to the internal combustion engine BKM . The transfer-free freewheel function of the freewheel clutch K1, on the other hand, is in the second engine operating mode MB2 ( 3 ) activated, i.e. when the electric machine is operating RSG in the direction of rotation of the first drive A1 opposite second drive direction of rotation A2 .

In addition, to implement the three operating modes MB1, MB2, GB in the centrifugal clutch K2, the torque-transmitting locking function in the generator operating mode GB ( 2 ) activated. In this case the load path runs L2 ( 2 ) from the internal combustion engine BKM via the internal combustion engine belt drive R _BKM as well as via the locked centrifugal clutch K2 to the electric machine RSG , while at the same time the freewheel function is activated in the overrunning clutch K1.

The transmission-free freewheeling function of the centrifugal clutch K2, on the other hand, is in the second engine operating mode MB2 ( 3 ) activated, i.e. when the electric machine is operating RSG in the opposite second drive direction of rotation A2 ( 3 ). The load path results in the second motor operating mode MB2 L5 , where the electric machine RSG in the second drive direction of rotation A2 rotates, so that the freewheel function is activated in both the overrunning clutch K1 and in the centrifugal clutch K1. In this way, in an engine-off phase (that is, when the internal combustion engine is temporarily shut down BKM ) or when the internal combustion engine is permanently shut down BKM the electric machine RSG the mechanical air conditioning compressor mKK independent of the internal combustion engine BKM drive.

The following is based on the 4th to 7th a concrete structure of the switchable pulley 9 as well as the non-rotatable pulley 11 with the two freewheel and centrifugal clutches K1 and K2: Accordingly, the two switchable and non-rotatable pulleys 9 , 11 axially immediately adjacent to one another on the electric machine shaft 1 arranged. A basic body 12th the switchable pulley 9 is with the radial interposition of the overrunning clutch K2 on the electric machine shaft 1 arranged. As from the 4th and 5 As can be seen, the centrifugal clutch K2 has a total of three centrifugal force elements which can be subjected to centrifugal force and which are arranged uniformly distributed around the circumference 15th on that between one in the 4th and 5 shown rest position and one in the 6th and 7th Locked position shown are adjustable. The basic body 12th the switchable pulley 9 is in the 4th with a diameter-reduced support ring 17th uniform material and elongated in one piece. The support ring 17th the switchable pulley 9 protrudes into an installation space 19th the non-rotating pulley 11 a. In the 1 is the installation space 19th between a radially outer ring of grooves 21st , a radially inner hub portion 23 and a connecting flange 25th the non-rotating pulley 11 arranged that the hub portion 23 with the radially outer ring of grooves 21st connects.

In the 5 is each of the centrifugal elements 15th in a radially aligned guide channel 27 guided radially adjustable. The respective guide channel 27 is in the support ring 17th the switchable pulley 9 axially open at the front. In the, in the 4th The assembly state shown is the axially open end face of the respective guide channel 27 from the connecting flange 25th the non-rotating pulley 11 closed, so that a reliable linear guide of the centrifugal force elements 15th is guaranteed.

According to the 5 is on the inner circumference of the ring of grooves 21st the non-rotating pulley 11 a counter contour 29 educated. When subjected to centrifugal force, this acts with a (in the 5 form-fitting contour indicated by dashed lines 16 of the respectively assigned centrifugal force element 15th together. In the in the 5 The rest position shown is between the support ring 17th the switchable pulley 9 and the inner circumference of the ring of grooves 21st the non-rotating pulley 11 a radial free space 31 educated. With a centrifugal force ( 6th and 7th ) can the respective centrifugal element 15th using up the radial free space 31 until it is in engagement with the one on the inner circumference of the ring of grooves 21st the non-rotating pulley 11 trained counter contour 29 come. In the radial space 31 is a ring spring 33 arranged according to the 8th is stretched with a predefined spring force F1 on the outer circumference of the support ring and in a rest position ( 5 ) the centrifugal elements 15th in their resting position.

Both on the outer circumference of the support ring and on the radially outer side of the centrifugal force elements 15th are spring grooves 35 formed in which the ring spring 33 is arranged.

If the centrifugal force is very high, the ring spring 33 Lift off radially outward from the outer circumference of the support ring. In order to maintain correct ring spring positioning in this case, the 4th or 6th on the inner circumference of the ring of grooves 21st a circumferential spring groove 37 educated. The ring spring lifts off the inner circumference of the support ring when there is a very strong centrifugal force 33 can therefore radially outward up to the inner circumference of the ring of grooves 21st formed spring groove 37 drive in.

As from the spring force-speed diagram of the 8th is the ring spring 33 clamped with the predefined spring force F1 on the outer circumference of the support ring, the value of which is approximately 750 N as an example. In the event of centrifugal force (i.e. in GB generator operation), the centrifugal force elements press 15th radially outwards until reaching the locking position ( 6th or 7th ). This leads to a stretching of the ring spring 33 , while building up the spring force up to a value of F2, which is in the 8th is approximately 1200 N by way of example. In the 8th sets the effect of centrifugal force on the centrifugal force elements 15th at one speed of the switchable pulley 9 of approximately 270 min ^{-1 as} an example. When a speed of approximately 330 min ^{-1 is reached} , the centrifugal force elements are 15th relocated to their locked position.

List of reference symbols

1

Electric machine shaft

3

Aggregates shaft

5

Internal combustion engine shaft

7th

Internal combustion engine-side pulley

9

switchable pulley of the electric machine shaft

11

non-rotating pulley of the electric machine shaft

12

Basic body of the switchable pulley

13

unit-side pulley

15th

Centrifugal elements

16

Form-fitting contour of the respective centrifugal force element

17th

Support ring

19th

Installation space

21st

Grooved wreath

23

Hub section

25th

Connecting flange

27

Guide channel

29

Counter contour

31

radial clearance

33

Ring spring

35, 37

Spring grooves

39

Freewheel outside

40

Pivot bearing

41

Clamping elements

42

Pivot bearing

43

Freewheel inside

BKM

Internal combustion engine

RSG

Electric machine

mKK

mechanical air conditioning compressor

R _BKM

Internal combustion engine belt drive

R _mKK

Unit belt drive

A1

first drive direction of rotation

A2

second drive direction of rotation

L1, L2, L3, L4, L5

Load paths

Claims (9)

Belt pulley arrangement with an electric machine (RSG) with an electric machine shaft (1) which can be driveably connected to an internal combustion engine shaft (5) via an internal combustion engine belt drive (R _BKM ), and via an _assembly belt drive (R _mKK ) with a Ancillary unit, in particular a mechanical air conditioning compressor (mKK), can be driven, with a switchable belt pulley (9), which is part of the internal combustion engine belt drive (R _BKM ), and a non-rotatable belt pulley (11) being arranged on the electric machine shaft (1) , which is part of the unit belt drive (R _mKK ), whereby the switchable belt pulley (9) can be coupled to or decoupled from the electric machine shaft (1) to transmit torque via a coupling _device depending on different operating modes (MB1, MB2, GB), wherein in a first engine operating mode (MB1) a power split takes place on the clutch device, in which a from the electric machine (RSG) gene ered drive torque in a load path (L1) from the electric machine shaft (1) in the direction of the internal combustion engine belt drive (R _BKM ) and in a load path (L2) from the electric machine shaft (1) in the direction of the unit belt drive (R _mKK ) is divided, and in a second motor operating mode (MB2) a drive torque generated by the electric machine (RSG) can be transmitted from the electric machine shaft (1) in a load path (L5) in the direction of the unit belt drive (R _mKK ) without power _split with a switchable belt pulley (9) decoupled from the electric machine shaft (1) in terms of force by means of the clutch device, characterized in that the clutch device has an overrunning clutch (K1) and a centrifugal clutch (K2), and that the two clutches ( K1, K2), depending on the mode of operation (MB1, MB2, GB), automatically creates a coupling or decoupling between the switchable pulley (9) and the drive shaft (1) place. Pulley arrangement according to Claim 1 , characterized in that in a generator mode (GB) a drive torque generated by the internal combustion engine (BKM) in a load path (L3) from the internal combustion engine (BKM) via the internal combustion engine belt drive (R _BKM ) to the electric machine shaft (1) and further to Electric machine (RSG) and a load path (L4) from the electric machine shaft (1) via the unit belt drive (R _mKK ) to the auxiliary unit (mKK). Pulley arrangement according to Claim 1 or 2 , characterized in that in the first motor operating mode (MB1) the overrunning clutch (K1) blocks torque-transmitting and the centrifugal clutch (K2) is transmission-free, that in the generator operating mode (GB) the overrunning clutch (K1) is transmission-free and the centrifugal clutch (K2) blocks torque-transmitting , and / or that in the second motor operating mode (MB2) both the overrunning clutch (K1) and the centrifugal clutch (K2) are free of transmission, and / or that in particular the torque-transmitting locking function of the overrunning clutch (K1) in the first motor operating mode (MB1) is activated, and the transmission-free freewheeling function is activated when the electric machine (RSG) is operated in a second driving direction (A2) opposite to the first driving direction of rotation (A1), and / or that the torque-transmitting locking function of the centrifugal clutch (K2) is activated in the generator mode (GB) is, and their transmission-free freewheeling function be is activated in the operation of the electric machine (RSG) in the opposite second drive direction of rotation (A2), and that in particular in the second motor operating mode (MB2) the electric machine (RSG) rotates in the second drive direction of rotation (A2) in which both the overrunning clutch (K1 ) and in the centrifugal clutch (K2) the freewheel function is activated, so that when the internal combustion engine (BKM) is shut down, the electric machine (RSG) drives the auxiliary unit (mKK) independently of the internal combustion engine (BKM). Pulley arrangement according to one of the preceding claims, characterized in that in the first motor operating mode (MB1) and in the generator operating mode (GB) the shafts (1, 3, 5) of the auxiliary unit (mKK), the electric machine (RSG) and the internal combustion engine (BKM ) rotate in the first drive direction of rotation (A1), and that in the second motor operating mode (MB2) the internal combustion engine shaft (5) is stationary and the electric machine shaft (1) and the unit shaft (3) in the opposite second drive direction of rotation (A2 ) rotate. Belt pulley arrangement according to one of the preceding claims, characterized in that the switchable belt pulley (9) is arranged on the electric machine shaft (1) with the overrunning clutch (K1) in between. Belt pulley arrangement according to one of the preceding claims, characterized in that the centrifugal clutch (K2) has at least one centrifugal force element (15) which can be acted upon by centrifugal force and which is adjustable between a rest position and a blocking position, and that the centrifugal force element (15) in the blocking position engages a mating contour (29) of the electric machine shaft (1), and is disengaged therefrom in the rest position. Pulley arrangement according to Claim 6 , characterized in that the non-rotatable belt pulley (11) and the switchable belt pulley (9) are arranged axially adjacent to one another on the electric machine shaft (1), and that in particular the non-rotatable belt pulley (11) provides an installation space (19) in which the centrifugal element (15) of the centrifugal clutch (K2) is arranged. Pulley arrangement according to Claim 7 , characterized in that the installation space (19) is formed on the side of the non-rotatable belt pulley (11) facing the switchable pulley (9), and / or that the installation space (19) is between a radially outer groove ring (21), a radially inner hub portion (23) and a connecting flange (25) of the rotationally fixed pulley (11) is arranged, which connects the hub portion (23) and the groove ring (21) to one another. Pulley arrangement according to Claim 8 , characterized in that the mating contour (29) is formed on the inner circumference of the grooved ring (21) of the non-rotatable pulley (11), and / or that the centrifugal clutch (K2) has a linear guide by means of which the centrifugal element (15) between its rest position and its locked position is adjustable.

Images