WO2021008759A1

WO2021008759A1 - Belt pulley assembly

Info

Publication number: WO2021008759A1
Application number: PCT/EP2020/064093
Authority: WO
Inventors: Alfred Rehr; Christian Glück
Original assignee: Audi Ag
Priority date: 2019-07-16
Filing date: 2020-05-20
Publication date: 2021-01-21
Also published as: DE102019210503B4; DE102019210503A1

Abstract

The invention relates to a belt pulley assembly comprising a shiftable belt pulley (9) and an axially adjacent rotationally fixed belt pulley (11), both of which are arranged on a drive shaft (1). The shiftable belt pulley (9) can be coupled to the drive shaft (1) so as to transmit a torque or can be decoupled from the drive shaft by means of a clutch device, namely on the basis of different operating modes (M1, MB2, GB) of the belt pulley assembly. According to the invention, the clutch device has a freewheel clutch (K1) and a centrifugal clutch (K2), which couples or decouple the shiftable belt pulley (9) to/from the drive shaft (1) on the basis of the operating mode (MB1, MB2, GB). The freewheel clutch (K1) and the centrifugal clutch (K2) are arranged in an installation area radially within the two belt pulleys (9, 11).

Description

Pulley assembly

DESCRIPTION: The invention relates to a pulley arrangement according to the preamble of claim 1.

Conventional vehicles have a drive for auxiliary units. Driven by the internal combustion engine, an electrical 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 solely because of air conditioning needs 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, this has significant disadvantages compared to the mechanically driven air conditioning compressor in terms of procurement costs, component weight and space requirements.

A generic belt pulley arrangement has an electric machine with an electric machine shaft on which a belt pulley that can be switched via a clutch device and a non-rotatable belt pulley are arranged. The switchable pulley can be connected to an internal combustion engine shaft via an internal combustion engine belt drive. In addition, the non-rotatable belt pulley is via an aggregate Belt drive can be drivably connected to an aggregate shaft. 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 direction of rotation of the drive on the internal combustion engine. In this case, the internal combustion engine can be started, for example, or a boost operation can take place in which the running internal combustion engine is supported with an additional electromotive torque. As an alternative to this, 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, namely when the internal combustion engine is shut down, that is to say drive off the auxiliary unit independently of the internal combustion engine.

The implementation of the above first motor operation, the second motor operation and the generator operation 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 a need for components and installation space.

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

The object of the invention is to provide a pulley arrangement with a switchable pulley and a non-rotatable pulley to provide, in which, compared to the prior art, the technical control effort and the space and component requirements are reduced.

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, the coupling device for the switchable pulley can have an overrunning clutch and a centrifugal clutch. The overrunning clutch and the centrifugal clutch open or lock automatically in the two engine operating modes and in the generator operating mode of the electric machine, that is, 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, when the internal combustion engine shaft is at a standstill), the electric machine can drive the auxiliary unit, in particular a mechanical air conditioning compressor, independently of the internal combustion engine.

In the first motor operating mode, the overrunning clutch can lock in a torque-transmitting manner and the centrifugal clutch can be transmission-free. In the generator 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 with a first driving direction of the electric machine shaft. In the first engine operating mode, the machine can either be used to start the engine or to perform a boost function while the internal combustion engine is running. In contrast, the transmission-free freewheeling function of the freewheeling clutch can be activated when the electric machine is operating in a second driving direction of rotation 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 drive 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 in both the overrunning clutch and in the centrifugal clutch, that is to say without transmission in the case of the clutches. 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 current practice, the overrunning clutch can have an overrunning clutch outside and an overrunning clutch 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 to a clamping position or 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 element in its rest position can be out of engagement with the counter contour of the electric machine shaft.

According to the invention, the non-rotatable belt pulley and the switchable belt pulley are axially directly adjacent to one another on the electric machine shaft arranged. With a view to implementation that is economical in terms of space, the two pulleys provide space in which the overrunning clutch and the centrifugal clutch are arranged. It is economical if the non-rotatable belt pulley provides a radially inner installation space. The centrifugal clutch element can be positioned in the installation space of the non-rotatable belt 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 a view 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 non-rotatable belt pulley. The connection flange connects the radially inner hub portion 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 designed in a space-saving manner directly on the inner circumference of the groove ring of the non-rotatable belt pulley.

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 blocking position. To implement the linear guide, the switchable belt pulley can be axially extended in one piece with a support ring of the same material. The support ring can be diametrically reduced compared to the switchable pulley and protrude nested in the assembly position in the installation space of the axially adjacent rotationally fixed pulley. In the support ring of the switchable pulley, at least one radially oriented 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 belt pulley can be axially open at the end face. In the assembled state, the axially open end face of the guide channel can be closed directly from the connecting flange of the non-rotatable belt pulley. In the second engine operating mode, the electric machine drives the Nebenaggre gat independently of the (shutdown) internal combustion engine. In this case, the electric machine shaft rotates together with the non-rotatable pulley which is arranged on it. In contrast, the internal combustion engine belt drive remains shut down together with the switchable pulley, so that a relative rotary movement takes place between the switchable (shut down) pulley and the non-rotating pulley and the electric machine shaft. In this case, the support ring of the switchable pulley can preferably be in sliding contact with the outer circumference of the hub section and with the connecting flange of the non-rotatable 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. As a result, the centrifugal element in its radially inner rest position can be out of sliding contact with the hub portion of the non-rotatable 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 non-rotatable 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 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 on the outer circumference of the support ring of the switchable pulley is stretched and / or moves the support ring outer circumference without interruption.

In order to position 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 is 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 grooved ring of the non-rotatable belt pulley, in which the annular spring that lifts off the inner circumference of the support ring can be inserted.

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 from the drive shaft via a coupling device to transmit torque Can be decoupled, depending on different operating modes of the pulley arrangement. 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 when the drive shaft rotates in a first drive direction of rotation, a load path L1 is formed from the drive shaft in the direction of the switchable pulley. 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 an opposite second drive direction of rotation, a load path L5 without power branching along the drive shaft is formed, namely under force - 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.

Show it:

1 to 3 are each views of a block diagram indicated

Pulley assembly in different Betriebszu states;

4 to 7 show sectional views of the coupling device with deactivated centrifugal clutch (FIGS. 4 and 5) and with activated centrifugal clutch (FIGS. 6 and 7); and

8 shows a spring force-speed diagram.

In FIG. 1, a pulley arrangement has an electric machine RSG, which is connected to a vehicle battery 14 via an electrical supply line. The electric machine RSG is drivingly connected to an internal combustion engine BKM of a vehicle and to a mechanical air conditioning compressor mKK which forms the auxiliary unit. An electric machine shaft 1 of the electric machine RSG, an aggregate shaft 3 of the air conditioning compressor mKK and an internal combustion engine shaft 5 are arranged axially parallel to one another and are driveably connected to one another via an internal combustion engine belt drive RBKM and an aggregate belt drive RmKK. The internal combustion engine belt drive RBKM has in FIG. 1 a belt pulley 7 which is seated in a rotationally fixed manner on the internal combustion engine shaft 5 and a switchable belt pulley 9 which is arranged on the electric machine shaft 1. The switchable pulley 9 can be coupled to the electric machine shaft 1 in a torque-transmitting manner or decoupled therefrom by means of a coupling device described later, depending on different operating modes MB1, MB2, GB. The Ag- The gregate belt drive RmKK has a non-rotatable belt pulley 11 arranged on the electric machine shaft 1 and a pulley 13 on the assembly side. In FIG. 1, the clutch device is made up of an overrunning clutch K1 and a centrifugal clutch K2. In the operating modes MB1, GB, MB2 illustrated with reference to FIGS. 1 to 3, these can automatically couple or uncouple so that the switching operations can be carried out without external hydraulic or electrical actuators. The operating modes MB1, GB, MB2 in which the pulley arrangement can be operated are described below with reference to FIGS. 1 to 3.

In FIG. 1, the pulley arrangement operates in the first motor mode MB1, in which the electric machine RSG executes an engine start or a boost function. In the first motor operating mode MB1, a drive torque is generated in the electrical machine RSG. At the coupling device of the switchable pulley 9 there is a power split in which the drive torque generated by the electric machine RSG is in a load path L1 from the electric machine shaft 1 in the direction of the internal combustion engine belt drive RBKM and into a load path L2 from the electric machine. Wave 1 is divided in the direction of the unit belt drive RmKK. The electric machine shaft 1 of the electric machine RSG drives with a first drive direction of rotation A1 (that is, clockwise rotation) on the internal combustion engine shaft 5 and on the assembly shaft 3, which also rotate in the first drive direction of rotation A1.

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

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

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

In addition, in order to implement the three operating modes MB1, MB2, GB in the centrifugal clutch K2, the torque-transmitting locking function is activated in the generator operating mode GB (FIG. 2). In this case, the load path L2 (FIG. 2) from the internal combustion engine BKM via the internal combustion engine belt drive RBKM and 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, however, is activated in the second motor operating mode MB2 (Figure 3), that is, when operating the electric machine RSG in the opposite second drive direction of rotation A2 (Figure 3). In the second motor operating mode MB2, the load path L5 results in which the electric machine RSG rotates in the second drive direction of rotation A2, so that the freewheel function is activated in both the freewheel clutch K1 and the centrifugal clutch K1. In this way, in an engine-off phase (that is, when the internal combustion engine BKM is temporarily shut down) or when the internal combustion engine BKM is permanently shut down, the electric machine RSG can drive the mechanical air-conditioning compressor mKK independently of the internal combustion engine BKM.

A specific structure of the switchable pulley 9 and the non-rotatable belt pulley 11 with the two freewheel and centrifugal clutches K1 and K2 is described below with reference to FIGS. 4 to 7: Accordingly, the two switchable and non-rotatable pulleys 9, 11 are axially immediately adjacent to one another the electric machine shaft 1 arranged. A base body 12 of the switchable belt pulley 9 is arranged on the electric machine shaft 1 with the radial interposition of the overrunning clutch K2. As can be seen from FIGS. 4 and 5, the centrifugal clutch K2 has a total of three centrifugal force elements 15 that can be subjected to centrifugal force distributed uniformly around the circumference and that are positioned between a rest position shown in FIGS. 4 and 5 and a locking position shown in FIGS. 6 and 7 are adjustable. The base body 12 of the switchable belt pulley 9 is lengthened in FIG. 4 in a uniform and one-piece manner with a support ring 17 of reduced diameter. The support ring 17 of the switchable pulley 9 protrudes into a space 19 of the rotationally fixed pulley 11. In Fig. 1, the installation space 19 is between a radially outer groove ring 21, a radially inner hub portion 23 and a connection Flange 25 of the non-rotatable pulley 11 is arranged, which section 23 connects the Nabenab with the radially outer groove ring 21.

In FIG. 5, each of the centrifugal force elements 15 is guided in a radially adjustable manner in a radially aligned guide channel 27. The respective guide channel 27 is designed in the support ring 17 of the switchable pulley 9 to be axially open at the front. In the assembled state shown in FIG. 4, the axially open end face of the respective guide channel 27 is closed by the connecting flange 25 of the non-rotatable belt pulley 11, so that operationally reliable linear guidance of the centrifugal force elements 15 is ensured.

According to FIG. 5, a mating contour 29 is formed on the inner circumference of the grooved ring 21 of the rotationally fixed pulley 11. When centrifugal force is applied, this interacts with a form-fitting contour 16 (indicated by dashed lines in FIG. 5) of the respective associated centrifugal force element 15. In the rest position shown in FIG 11 a radial free space 31. When centrifugal force is applied (FIGS. 6 and 7), the respective centrifugal force element 15 can come into engagement with the counter contour 29 formed on the inner circumference of the groove ring 21 of the non-rotatable pulley 11, using up the radial free space 31 In the free space 31 there is an annular spring 33 which, according to FIG. 8, is stretched with a predefined spring force F1 on the outer circumference of the support ring and in a rest position (FIG. 5) holds the centrifugal force elements 15 in their rest position.

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

In the event of a very high centrifugal force load, the annular spring 33 can lift off radially outward from the outer circumference of the supporting ring. In order to maintain a perfect annular spring positioning in this case, FIG. 4 or FIG 6 on the inner circumference of the ring of grooves 21, a circumferential spring groove 37 is formed. The ring spring 33, which lifts off the inner circumference of the support ring when the action of centrifugal force is very strong, can therefore move radially outward into the spring groove 37 formed on the inner circumference of the groove ring 21.

As can be seen from the spring force-speed diagram in FIG. 8, the annular spring 33 is stretched with the predefined spring force F1 on the outer circumference of the support ring, the value of which is approximately 750 N by way of example. With a centrifugal force (that is, in generator operation GB), the centrifugal force elements 15 push radially outward until reaching the locking position (Fi gur 6 or 7). This leads to an expansion of the ring spring 33, with the spring force being built up to a value of F2, which is approximately 1200 N in FIG. In FIG. 8, the effect of centrifugal force relies on the centrifugal force elements 15 a at a rotational speed of the switchable pulley 9 by way of example, about 270 min ^1. When a speed of approximately 330 min ^{-1 is reached} , the centrifugal force elements 15 are shifted to their locking position.

REFERENCE LIST

I electrical machine shaft

3 aggregate shaft

5 internal combustion engine shaft

7 engine-side pulley

9 switchable pulley of the electric machine shaft

I I non-rotatable pulley of the electric machine shaft

12 Basic body of the switchable pulley

13 Belt pulley on the unit side

15 centrifugal elements

16 Form-fit contour of the respective centrifugal force element

17 support ring

19 installation space

21 grooved ring

23 hub section

25 connecting flange

27 guide channel

29 Counter contour

31 radial clearance

33 ring spring

35, 37 spring grooves

39 freewheel outside

40 pivot bearings

41 clamping elements

42 pivot bearings

43 Freewheel inside

BKM internal combustion engine

RSG electric machine

mKK mechanical air conditioning compressor

RBKM internal combustion engine belt drive

RmKK aggregate belt drive

A1 first drive direction of rotation

A2 second drive direction of rotation

L1, L2, L3, L4, L5 load paths

Claims

PATENT CLAIMS:

1. Belt pulley arrangement with a switchable belt pulley (9) and an axially adjacent non-rotatable belt pulley (11), both of which are arranged on a drive shaft (1), the switchable

Belt pulley (9) can be coupled to the drive shaft (1) in a torque-transmitting manner by means of a coupling device or can be decoupled therefrom, depending on different operating modes (MB1, MB2, GB) of the pulley arrangement, characterized in that the coupling device has a One-way clutch

(K1) and a centrifugal clutch (K2) which, depending on the operating mode (MB1, MB2, GB), provide a coupling or decoupling between the switchable belt pulley (9) and the drive shaft (1), and that the overrunning clutch (K1 ) and the centrifugal clutch (K2) are arranged in a space radially inside the two belt pulleys (9, 11).

2. Belt pulley arrangement according to claim 1, characterized in that the switchable belt pulley (9) is arranged on the drive shaft (1) with a radial interposition of the overrunning clutch (K2), and / or that the non-rotatable belt pulley (11) has an installation space (19 ) provides, in which a centrifugal force element (15) of the centrifugal clutch (K2) is arranged, and that in particular the centrifugal force element (15) is adjustable under the effect of centrifugal force between a rest position and a locking position, and / or that the centrifugal force element (15) in the

Locking position is in engagement with a mating contour (29) of the generator shaft (1), and in the rest position is out of engagement therewith.

3. Belt pulley arrangement according to one of claims 1 or 2, characterized in that the installation space (19) is formed on the side of the non-rotatable belt pulley (11) facing the switchable belt pulley (9), and / or that the installation space (19 ) between a radially outer ring of grooves (21), a radially inner hub section (23) and a connecting flange (25) of the torsion-proof belt Human disk (11) is arranged, which connects the hub portion (23) and the groove ring (21) with each other, and / or that the counter contour (29) is formed on the inner circumference of the groove ring (21) of the non-rotatable belt pulley (11).

4. Pulley arrangement according to one of claims 2 or 3, characterized in that the centrifugal clutch (K2) has a line arführung, by means of which the centrifugal element (15) is adjustable between its rest position and its locking position, and that in particular to realize the Linear guide, the switchable belt pulley (9) is axially extended with a support ring (17) which protrudes in the assembly position into the installation space (19) of the axially adjacent non-rotating pulley (11), and that the switchable in the support ring (17) Belt pulley (9) has at least one guide channel (27) in which the centrifugal force element (15) is guided in a radially adjustable manner.

5. Pulley arrangement according to one of claims 2 to 4, characterized in that the centrifugal force element (15) is spring-biased with a spring (33) in its radially inner rest position, and / or that the centrifugal force element (15) in its radially inner rest position with a radial stop of the switchable pulley (9) is in contact, that is in particular out of sliding contact with the Na benabschnitt (23) of the rotationally fixed pulley (11).

6. Pulley arrangement according to one of claims 4 or 5, characterized in that in the radial direction between the support ring (17) of the switchable pulley (9) and the inner circumference of the grooved ring (21) of the rotationally fixed pulley (11) a radial free space (31 ) is formed, and that when centrifugal force is applied, the centrifugal force element (15) comes into engagement with the counter-contour (29) formed on the inner circumference of the grooved ring (21) of the rotatable pulley (11), using up the radial free space (31).

7. Pulley arrangement according to claim 6, characterized in that the spring (33) is arranged in the radial free space (31), which is preferably continuously open on the circumference, and that in particular the spring (33) is an annular spring which is applied to the outer circumference of the support ring (17) of the switchable pulley (9) is stretched and / or moves around the outer circumference of the support ring (17).

8. Pulley arrangement according to claim 7, characterized in that a circumferential spring groove (35) is formed on the outer circumference of the support ring (17) of the switchable pulley (9) and on the outer circumference of the centrifugal force element (15), in which the annular spring (33) runs.

9. Belt pulley arrangement according to claim 7 or 8, characterized in that when the centrifugal force is very high, the ring spring (33) lifts off radially outward from the outer circumference of the support ring, and that on the inner circumference of the grooved ring (21) of the non-rotatable belt pulley (11) a circumferential spring groove (37) is formed into which the annular spring (33) lifted from the inner circumference of the support ring can be inserted.