WO2021204324A1

WO2021204324A1 - Shiftable electromagnetic clutch, and clutch assembly

Info

Publication number: WO2021204324A1
Application number: PCT/DE2021/100251
Authority: WO
Inventors: Marc Finkenzeller
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2020-04-09
Filing date: 2021-03-12
Publication date: 2021-10-14
Also published as: DE102020109940B4; CN219062268U; DE102020109940A1

Abstract

The invention relates to a shiftable electromagnetic clutch and to a clutch assembly, in particular a shiftable electromagnetic clutch for transmitting a torque on a rotational axis (1) from a drive side (10) to an output side (11). A magnetic device (20) for exerting a magnetic attractive force (24) as well as a first contact element (30) are arranged on one side of the electromagnetic clutch, and a second contact element (40), by means of which a torque can be transmitted upon contacting the first contact element (30), a hub element (60) for receiving a torque applied to the second contact element (40), and an attraction element (70), which can be axially moved relative to the hub element (60) by means of the attractive force (24) of the magnetic device (20) and which is connected to the second contact element (40) in a rotationally and axially fixed manner, are arranged on the other side of the electromagnetic clutch. The invention is characterized in that the electromagnetic clutch additionally has a positioning element (80) which is fixed to the hub element (60) or the attraction element (70) in a frictionally locking manner and which can be axially moved while overcoming a frictional force, and a stop (91) is arranged on the respective other element, i.e. the hub element (60) or the attraction element (70), on the side of the positioning element (80) axially facing the magnetic device (20).

Description

Switchable magnetic coupling and coupling arrangement

The present invention relates to a switchable magnetic coupling and a coupling arrangement which comprises the switchable magnetic coupling.

The function of the magnetic coupling is based on the effect of a magnetic field. This type of coupling includes, in particular, the electromagnetic coupling, which is also used as an electrically remotely switchable, non-positive or positive coupling in motor vehicles, and in particular is designed as a pilot coupling for actuating an actuation system of a main clutch in order to open and / or close the main clutch.

There is a constant need to be able to open and close the pilot clutch and the main clutch comfortably with little structural effort.

Magnetic couplings may have the disadvantage that the force required to close the magnetic coupling in the open state of the coupling depends on the width of the working air gap or on the distance between the components of the magnetic coupling to be axially displaced by magnetic force. This means that the larger the working air gap, the higher the required starting current must be defined in order to be able to securely close the magnetic coupling. In order to ensure that a sufficiently large magnetic force can be produced, correspondingly large or powerful magnets are to be provided, which, however, have the disadvantage that they are space-intensive and / or cost-intensive.

On the other hand, it must also be ensured that the magnetic coupling can be opened without generating drag torques in order to avoid friction-related wear when the magnetic coupling is open. Accordingly, a precisely defined, optimal air gap must be maintained between the clutch components that are in contact with one another and transmit the torque in the closed state. Furthermore, it cannot be ruled out that There are manufacturing-related tolerances in the magnetic coupling, which also make it necessary to set the working air gap with great accuracy. This is possible on the one hand by means of very precise measurement processes during assembly and the setting of the air gap using spacers. Another possibility is to store the input side and the output side of the magnetic coupling separately, which, however, has the disadvantage of having to overcome drag torques.

Proceeding from this, the present invention is based on the object of providing a magnetic coupling and a coupling arrangement equipped therewith, which combine, in a cost-effective design, low-wear operation with easy-to-implement assembly.

This object is achieved by the switchable magnetic coupling according to claim 1 and by the coupling arrangement according to claim 10. Advantageous embodiments of the switchable magnetic coupling are specified in the dependent claims 2 to 9.

The features of the claims can be combined in any technically meaningful manner, in which case the explanations from the following description and features from the figures can also be used, which include additional embodiments of the invention.

The invention relates to a switchable magnetic coupling for transmitting a torque on an axis of rotation from a drive side to an output side, a magnetic device for exerting a magnetic force of attraction and a first contact element being arranged on one side of the magnetic coupling. On the other side of the magnetic coupling are a second contact element, with which a torque can be transmitted when contacting the first contact element, as well as a hub element for absorbing a torque applied to the second contact element, and one that is axially displaceable with respect to the hub element by the attraction of the magnetic device Attraction element, which is rotatably and axially fixedly connected to the second contact element, arranged. The magnetic coupling also has a positioning element which is frictionally fixed on the hub element or the attraction element and can be axially displaced while overcoming the frictional force. On the other element of the hub element and the attraction element, a stop is arranged on a side of the positioning element axially facing the magnetic device, for contacting the positioning element in order to limit a distance of the attraction element from the magnetic device.

In the context of the present invention, the term “axial” always refers to the axis of rotation of the magnetic coupling.

The magnetic coupling thus produces a magnetic force of attraction from a drive side to an output side.

The first contact element can be designed as a first friction element, which at the same time has the function of a first hub for coupling to a first shaft, it being provided in particular that the first contact element is arranged so that it can rotate relative to the magnetic device.

Correspondingly, the second contact element can also be designed as a second friction element, with which a torque can be transmitted in a frictionally locking manner when the contact element is applied to the first contact element.

The hub element assigned to the second contact element is designed to transmit the torque applied to the second contact element directly or indirectly to a shaft connected to the hub element.

Due to the fact that the positioning element is axially displaceable, it can be positioned in a simple manner at an axial position in which the attraction element, also known as the armature disk, has an optimal and defined distance from the magnetic device when the stop is in contact with the positioning element. This ensures that the attraction element is positioned so close to the magnetic device, even when the clutch is disengaged, that the magnetic device can exert a sufficiently strong magnetic force on the attraction element to prevent the attraction element and thus also the to move the second contact element in the direction of the magnetic device in such a way that the contact elements are brought into contact with one another and can thus transmit torque.

In one embodiment it is provided that the other element of the hub element and the attraction element on the side of the positioning element axially facing away from the stop has a driving device at a distance equal to the sum of the axial width of the positioning element and a desired gap width between the first contact element and the second contact element corresponds to. The entrainment device is designed to move the positioning element axially in the direction of the magnetic device while overcoming the frictional force when the element having the entrainment device is displaced in the direction of the magnetic device.

Due to the fact that the first contact element is arranged axially fixed in relation to the magnetic device and the second contact element is arranged axially fixed in relation to the attraction element, the gap between the contact elements also defines the distance between the magnetic device and the attraction element.

The entrainment device ensures during assembly that when the attraction element and the second contact element move axially in the direction of the magnetic device, the positioning element is moved sufficiently far, overcoming the frictional force, until the contact elements are brought into contact with one another.

Due to the fact that the axial distance between the driving device and the stop corresponds to the sum of the axial width of the positioning element and the desired gap width between the first contact element and the second contact element, a distance can then be set by a restoring force between the attraction element and the hub element of the attraction element and thus also of the second contact element are carried out by the magnetic device, which, however, can only be carried out until the stop rests on the positioning element. Overall, it can thus be ensured by means of the entrainment device that the gap between the contact elements is not made too small when the magnetic coupling is installed and accordingly the occurrence of drag torques and the associated wear are prevented.

In addition, in the event of operational wear of the contact elements, in particular if they are designed as friction elements or friction disks, and an accompanying enlargement of the gap between the contact elements, the effect of the attraction force from the magnetic device on the attraction element when the driver device is in contact the positioning element, the frictional force fixing the positioning element can be overcome and accordingly the positioning element can be shifted in the direction of the magnetic device until the contact elements are in contact with one another. In this way, an automatic self-adjustment of the magnetic coupling with regard to its gap width is guaranteed.

Furthermore, it is provided in an advantageous embodiment that the attraction element and the hub element are connected to one another via a spring device for exerting a restoring force on the attraction element.

The hub element is fixed axially. The restoring force brings about a restoring movement of the attraction element and thus also of the second contact element from a closed position, in which the contact elements are in contact with one another, into an open position, in which the magnetic coupling is opened.

In particular, the spring device is formed by a plurality of leaf springs which connect the hub element to the attraction element.

The spring device also serves to transmit the torque from the second contact element to the hub element.

The maximum restoring force brought about by the spring device on the attraction element should be less than the frictional force fixing the positioning element. This ensures that the positioning element cannot be displaced by the restoring force even when the contact elements are in contact with one another, so that the set width of the gap between the contact elements is maintained.

Furthermore, the magnetic device can be arranged so that it can rotate, and the first contact element can be arranged so as to be rotatable with respect to the magnetic device. The magnetic device can include a housing in which one or more magnets of the magnetic device are accommodated.

In one embodiment, a rotary bearing is arranged between the magnetic device and the first contact element for the purpose of supporting the first contact element on the magnetic device while at the same time enabling the relative rotation.

The first contact element can also be designed as a hub.

The magnetic device can be positioned on the side of the first contact element axially opposite the gap or the second contact element, so that the first contact element is axially between the magnetic device and the second contact element and the magnetic attraction force produced by the magnetic device is applied the attraction element acts through the first contact element.

In particular, the second contact element and the displaceable attraction element can be designed as an integral component.

The second contact element can be formed by a shaped element facing the first contact element or a friction surface.

When the attraction element is attracted by the magnetic device, the second contact element is correspondingly also displaced and brought into contact with the first contact element. In a further advantageous embodiment of the switchable magnetic coupling, the two contact elements are friction elements for the frictional transmission of torque from the drive side to the output side.

For this purpose, each of the contact elements can have a friction lining.

The positioning element can be designed as a friction ring which, with a radially oriented side, rests against the hub element or against the attraction element under radial prestress. Correspondingly, a radial normal force acts on the friction ring, from which the friction force fixing the friction ring results as a function of the friction factor acting between the friction ring and the element carrying the friction ring.

A groove can be formed in the element on which the stop is arranged, in which the friction ring is arranged and which forms the stop with its wall facing the magnetic device and forms the entrainment device with its wall facing away from the magnetic device. In one embodiment, it is provided that the positioning element, designed as a friction ring, sits with its radial inside under radial tension on a cylinder jacket surface of a shoulder of the hub element. The radial outside of the friction ring is located in a groove that is formed in the attraction element. The axial width of the groove is as large as the sum of the width of the friction ring and the set gap between the contact elements.

Another aspect of the present invention is a clutch arrangement for a motor vehicle, which comprises a switchable magnetic clutch according to the invention and a main clutch, the switchable magnetic clutch serving as a pilot clutch of the main clutch.

This means that the magnetic coupling is designed as a device for actuating an actuation system of the main coupling in order to open and / or close the main coupling. The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way restricted by the purely schematic drawings, it being noted that the exemplary embodiments shown in the drawings are not restricted to the dimensions shown. It is shown in

Figure 1: the switchable magnetic coupling in the open state,

FIG. 2: the switchable magnetic coupling in the closed state, and FIG. 3: a force-displacement diagram.

First, the structure of the switchable magnetic coupling is explained with reference to FIG. The switchable magnetic coupling comprises, arranged on a common axis of rotation 1 on a drive side 10, a magnetic device 20 which comprises a magnet 21 in a housing 22. A first contact element 30, which is arranged rotatably with respect to the magnetic device 20, is mounted radially and axially on the housing 22 via a rotary bearing 23.

This first contact element 30 is used to contact a second contact element 40, which is arranged on the output side 11 of the magnetic coupling.

In the embodiment shown here, the second contact element 40 is designed as an integral component comprising an attraction element 70 of the magnetic coupling. Correspondingly, an attractive force 24 can be exerted on the attraction element 70 by means of the magnetic device 20, so that the latter moves in the direction of the magnetic device 20 while overcoming a gap 50 between the second contact element 40 and the first contact element 30. Due to the fact that the attraction element 70 and the second contact element 40 are designed as an integral component, the second contact element 40 thus comes to bear on the first contact element 30.

Furthermore, the magnetic coupling comprises a hub element 60 on the output side 11, which is rotationally fixed to the attraction element 70 via a spring device 100 is coupled. In the embodiment shown here, the spring device 100 is formed by a plurality of leaf springs 110 distributed around the circumference.

In the embodiment shown here, the first contact element 30 serves as a positively locking connecting element with a first shaft, not shown. In the embodiment shown here, the hub element 60 is used for the form-fitting connection to a second shaft, not shown here.

On a shoulder 61 of the hub element 60 sits a positioning element 80 designed as a friction ring with a radially acting preload 82, so that a normal force 83 acts radially on the radial inside of the positioning element 80, which depending on the prevailing friction conditions between the positioning element 80 and the shoulder 61 corresponding frictional force forms, which fixes the positioning element 80 in the axial direction.

The positioning element 80 is located within a groove 90 formed by the attraction element 70. In the situation shown in FIG remove the attraction element 70 and consequently also the second contact element 40 coupled therewith too far from the magnetic device 20.

During the assembly of the magnetic coupling, the frictional force fixing the positioning element 80 can be adjusted in its axial position in such a way that a gap 50 with an optimal gap width 51 is formed between the contact elements 30, 40.

When the magnet 21 of the magnetic device 20 is activated, a magnetic flux 25, as shown in FIG. 2, forms in the magnetic coupling. As a result, an attractive force 24 is exerted on the attraction element 70 by the magnetic device 20, so that it is displaced in the direction of the magnetic device 20 and the gap 50 shown in FIG. 1 is closed so that the two contact elements 30, 40 rest against one another. In the embodiment shown here, the first contact element 30 comprises a friction lining 31 to increase the friction factor between the contact elements 30, 40 for the purpose of frictional transmission of a torque between the contact elements 30, 40. Due to the axial displacement of the attraction element 70 and thus also of the second contact element 40 in the direction of the magnetic device 20, the stop 91 of the groove 90 in the attraction element 70 has become detached from the positioning element 80. It can now be seen that the positioning element 80 rests with its side axially opposite the stop 91 against a driver device 92, which is also formed by the groove 90. This entrainment device 92 ensures that when the magnetic coupling is installed, the positioning element 80 can be pushed in the direction of the magnetic device 20 by means of the entrainment device 92, overcoming the frictional force, until the contact elements 30, 40 come to rest against one another. The width of the groove 90 is dimensioned such that it corresponds to the sum of the axial width 81 of the positioning element 80 and the gap width 51.

When the magnetic effect is canceled and due to a restoring force 111 exerted on the attraction element 70 by the spring device 100, the attraction element 70 is moved again into an axial position, which is shown in FIG. 1, in which the positioning element 80 rests against the stop 91. The restoring force 111, which is brought about by the spring device 100 or its leaf springs 110, must not be greater than the frictional force fixing the positioning element 80.

The entrainment device 92 ensures that in the event of an increase in the gap width 51 due to wear and a resulting larger axial displacement of the second contact element 40, the positioning element 80 can be displaced while overcoming the fixing frictional force to such an extent that the contact elements 30, 40 come to rest again come. An automatic readjustment can accordingly take place through the magnetic coupling.

FIG. 3 shows a force-displacement diagram to illustrate the attraction force 24 acting as a function of the gap width 51. It can be seen that an attraction force 24 caused by the magnetic device 20 is greater, the smaller the distance to be covered between the contact elements 30, 40 is or the smaller the gap width 51 is. It can also be seen from this that the decrease in the attractive force 24 runs exponentially as the gap width 51 increases. The positioning element 80 and the stop 91 ensure that the second contact element 40 and thus also the attraction element 70 cannot move so far away from the magnetic device 20 that the attraction force becomes so low that the contact elements 30, 40 cannot reliably contact can be guaranteed to each other.

The entrainment device 92 in turn has the effect that when the clutch is disengaged, the contact elements 30, 40 cannot be positioned so close to one another that a drag torque between the contact elements 30, 40 and consequently increased wear can occur. In particular, it is provided that the working area 120 shown here can be achieved by a corresponding axial positioning of the

Positioning element 80 as well as by a corresponding distance between the stop 91 and the entrainment device 92 is realized.

With the magnetic coupling proposed here, the working air gap can be reduced to a minimum, so that the magnetic device only has to be dimensioned so powerfully that the minimum working air gap can be closed. Correspondingly, a lower current is also required in order to be able to close the magnetic coupling. Furthermore, the magnetic coupling has the advantage that the assembly can be carried out with less effort.

Reference list

I axis of rotation

10 drive side

I I output side

20 magnetic device

21 magnet

22 housing

23 pivot bearings

24 attraction

25 magnetic flux

30 first contact element

31 friction lining

40 second contact element

50 gap

51 gap width

60 hub element

61 paragraph

70 element of attraction

80 positioning element

81 axial width of the positioning element

82 radial preload

83 normal force

90 groove

91 stop

92 Take-away device

100 spring device 110 leaf spring

I I I restoring force

120 work area

Claims

1. Switchable magnetic coupling for transmitting a torque on an axis of rotation (1) from a drive side (10) to an output side (11), with a magnetic device (20) for exerting a magnetic force of attraction (24) and a first on one side of the magnetic coupling Contact element (30) are arranged, and on the other side of the magnetic coupling a second contact element (40), with which a torque can be transmitted when contacting the first contact element (30), as well as a hub element (60) for receiving a contact element (40) on the second contact element (40) ) applied torque, and a relative to the hub element (60) by attraction (24) of the magnetic device (20) axially displaceable attraction element (70), which is rotationally fixed and axially fixed to the second contact element (40), are characterized that the magnetic coupling is furthermore a frictionally fixed on the hub element (60) or the attraction element (70) and under over winding of the frictional force has axially displaceable positioning element (80), and a stop (91) is arranged on the respective other element of the hub element (60) and attraction element (70) on a side of the positioning element (80) axially facing the magnetic device (20) for engaging the positioning element (80) to limit the distance of the attraction element (70) from the magnetic device (20).

2. Switchable magnetic coupling according to claim 1, characterized in that the other element of the hub element (60) and attraction element (70) on the side of the positioning element (80) axially facing away from the stop (91) has a driving device (92) at a distance, which corresponds to the sum of the axial width (81) of the positioning element (80) and a desired gap width (51) between the first contact element (30) and the second contact element (40), wherein the entrainment device (92) is set up for a displacement of the element (60,70) having the entrainment device (92) in the direction of the magnetic device (20) To move the positioning element (80) axially in the direction of the magnetic device (20) while overcoming the frictional force.

3. Switchable magnetic coupling according to one of the preceding claims, characterized in that the attraction element (70) and the hub element (60) are connected to one another via a spring device (100) for exerting a restoring force (111) on the attraction element (70).

4. Switchable magnetic coupling according to claim 3, characterized in that the maximum restoring force (111) caused by the spring device (100) on the attraction element (70) is less than the frictional force fixing the positioning element (80).

5. Switchable magnetic coupling according to one of the preceding claims, characterized in that the magnetic device (20) is arranged non-rotatably and the first contact element (30) is arranged rotatably with respect to the magnetic device (20).

6. Switchable magnetic coupling according to one of the preceding claims, characterized in that the second contact element (40) and the displaceable attraction element (70) are designed as an integral component.

7. Switchable magnetic coupling according to one of the preceding claims, characterized in that the two contact elements (30, 40) are friction elements for the frictional transmission of torque from the drive side (10) to the output side (11).

8. Switchable magnetic coupling according to one of the preceding claims, characterized in that the positioning element (80) is designed as a friction ring which, with a radially oriented side, is radially pretensioned (82) on the hub element (60) or on the attraction element (70) is present.

9. Switchable magnetic coupling according to claim 8, characterized in that a groove (90) is formed in the element on which the stop is arranged, in which the friction ring is arranged, and which with its wall facing the magnetic device (20) forms the stop (91) and forms the entrainment device (92) with its wall facing away from the magnetic device (20).

10. Coupling arrangement for a motor vehicle, comprising a switchable magnetic coupling according to one of claims 1 to 9 and a main clutch, the switchable magnetic coupling serving as a pilot clutch of the main clutch.