DE102015220920B4 - Assembly with a friction device - Google Patents

Abstract

Assembly with a torque-transmitting input element, preferably a rotor, a spindle or the like, with a torque or linear force-transmitting output element, such as a spindle or a spindle nut or the like, the input element and the output element being coupled to one another, in particular for actuation a clutch of a vehicle and wherein the assembly is at least part of a transmission and/or actuator, wherein the torque is transmitted via a torque path from the input element to the output element, wherein a friction device is provided parallel to the torque path, which generates additional friction between the input and output element, wherein the additional friction is generated as a function of the direction of rotation of the input and/or output element, characterized in that the friction device comprises at least two components (2, 3) rotatable relative to one another, between which three accessible components (2, 3) there is a wrap spring element (1) which influences the efficiency/friction when the components (2, 3) rotate relative to each other and which has at least two active areas (1.1, 1.2) nested radially and axially in one another and connected to one another in one piece. having.

Description

The invention relates to an assembly with a friction device and with at least two components that can be rotated relative to one another, which is used in particular for actuating a clutch of a motor vehicle and is at least part of a transmission and/or actuator.

The actuators used, for example, to actuate a clutch of a motor vehicle can convert the rotational movement of a component into an axial movement of another component. The actuator itself can be any type of linear actuator, z. B. a PWG actuator (PWG planetary roller screw drive), a hydraulic slave cylinder, etc.

Planetary roller screw drives (PWG) usually consist of a spindle, a spindle nut and planetary rolling elements arranged between them over the circumference and accommodated in a planetary carrier. In this case, the spindle, spindle nut and planetary rolling elements have profiling in order to transmit a rotary movement between the spindle and spindle nut, with one of the components spindle or spindle nut being driven in rotation and the other component in a non-rotatable arrangement along the longitudinal axis of the spindle being displaced by an axial path corresponding to the gear ratio set . Here, the planetary rolling elements have two different profile sections, which mesh with sections of the spindle or the spindle nut designed in a complementary manner. As a result, better efficiency is achieved compared to mounting the spindle directly on the spindle nut.

From the DE 10 2010 047 800 A1 For example, an arrangement of a planetary roller gear is known in which an actuator part of a hydrostatic actuator designed as a piston of a master cylinder is coupled axially fixed to the spindle arranged in a rotationally fixed and axially displaceable manner, the axially fixed spindle nut being driven by an electric motor. If the spindle nut is rotated, the spindle and spindle nut are displaced axially in relation to one another. Since the cylinder housing that accommodates the piston and forms a pressure chamber with it is fixed and the spindle nut is supported axially on it, the piston builds up pressure depending on the rotary drive of the spindle nut, for example to actuate motor vehicle components such as brakes, friction clutches and the like.

In such efficiency-optimized and z. B. by means of an electric motor driven spindle drives, which are used in actuators such as hydrostatic clutch actuators, and which work against a load, for example a clutch characteristic, there is a problem that when it is necessary to hold a specific position, a holding current and thus a holding torque is required in the electric motor because the spindle drive (e.g. PWG) is not self-locking. These actuators therefore require a permanent holding current or in the event of a power failure/fault (e.g. cable break, connector drop) this position cannot be maintained. When the clutch is pushed open by the actuator, there is a risk that the clutch will close unintentionally.

It is also known to use wrap springs, for example for clutches. A wrap spring usually consists of a metallic wire which extends in several coils around a cylindrical part. A frictional force acts between this spring and the cylindrical part when the cylindrical part rotates. This can be influenced by tightening or releasing the wrap spring.

A wrap spring clutch usually consists of a helical spring wound on a shaft or cylindrical body, which is attached to the drive on one side. The entrainment effect is based on the fact that the entrainment torque increases and accumulates with each turn due to friction. As a result, due to the wrap, the force causing this friction increases at the same time. In the opposite direction, there is only a small amount of friction. The spring slightly increases in diameter, but does not unwind. The wrap spring is also used in slipping clutches due to the friction that remains in freewheeling operation. As a freewheel element, it has a self-reinforcing (blocking) effect in one direction and a cancellation of this function in the other direction, with the spring only having to be twisted against its basic friction.

From the pamphlet DE 10 2007 047 394 A1 For example, a torsional vibration damper is known which has at least two parts which can be rotated relative to one another counter to the action of a damping device with energy storage devices acting in the circumferential direction, one of which can be connected to a drive machine and the other to a shaft to be driven, with an additional between the two parts being connected to the A damping device is provided with a torque limiter connected in series, which is effective in at least one of the possible relative directions of rotation between the two parts and comprises at least one wrap spring clutch which acts as a freewheel when a predetermined angle of rotation is reached between the two parts and comprises at least one wrap spring element. This solution is characterized in that at least one End of the wrap-spring element is non-rotatably connected to a ring element, which has support areas for the energy storage device acting in the circumferential direction and/or control areas for the freewheeling effect. The ring element serves to absorb forces and to introduce them into the wrap spring element. The wrap-spring element is preferably arranged between two ring elements in the axial direction. At least one shell is arranged in the radial direction between the wrap-spring element and the energy stores in order, among other things, to support centrifugal forces of the energy stores acting in the circumferential direction.

In an as yet unpublished technical solution by the applicant, an assembly with a friction device with at least two mutually rotatable components, in particular for actuating a clutch of a vehicle, is proposed, in which between the components that can be rotated relative to one another, a relative rotation of the components increases the efficiency/ the friction influencing coil spring is arranged. The helical spring forms a coil spring, at least in some areas, which can be a simple coil spring, a double coil spring or a coil torsion spring. The double wrap spring described here has two active areas that are arranged axially one behind the other. As a result, a relatively large axial space is required. Such a solution is in the post-published WO 2015/048 961 A2 shown.

Another technical solution by the applicant that has not yet been published also describes an assembly with a friction device with at least two components that can be rotated relative to one another, between which a wrap spring is arranged, which has two wrap spring regions coupled to one another, with a slight rotation of the components in one direction of rotation Friction and in the other direction a high friction can be generated. The two wrap spring areas are coupled by a connecting piece, which is designed as a sleeve or ring and positions the two wrap spring areas radially nested in one another in such a way that torques can be transmitted from the first wrap spring area to the second wrap spring area and vice versa. The two wrap spring areas are here realized by two different wrap springs. This solution is characterized by a smaller space requirement in the axial direction. In addition, larger drag torque differences can be realized with this design due to the different cross-sections/diameters of the inner and outer springs. However, there is the disadvantage here that the multi-part structure of the wrap spring makes assembly more difficult and the costs increase due to the use of the connecting element connecting the two wrap spring areas.

The object of the invention is to provide an assembly with a torque-transmitting input element, preferably a rotor, a spindle or the like, with a torque or linear force-transmitting output element, such as a spindle or a spindle nut or the like, the input element and the output element having are coupled to one another, in particular for the actuation of a clutch of a vehicle and wherein the assembly is at least part of a transmission and/or actuator, with the torque being transmitted via a torque path from the input element to the output element, with which the friction and thus the efficiency between the relative to each other rotatable components is variable.

The object is solved by the features of the first claim. Advantageous configurations result from the dependent claims.

The assembly has a friction device parallel to the torque path, which generates additional friction between the input and output elements, the additional friction being generated as a function of the direction of rotation of the input and/or output element.

There is more friction in one direction of rotation and less friction in the other direction.

The relationship between the direction of rotation and friction is advantageously selected so that when the assembly changes state from an energetically less favorable state to an energetically more favorable state, higher friction is generated than in the opposite case, so that self-locking is achieved in a state for which otherwise energy would have to be expended to maintain it.

The dependence of the friction device on the direction of rotation is preferably so pronounced that only the relative direction of rotation of the output element to the input element or vice versa is important.

The input element can be a rotor of an electric motor that actuates the assembly, a shaft or a spindle, in particular a threaded spindle or a similar component which is driven by the electric motor.

The output element, in turn, can be a spindle, in particular a threaded spindle, which is driven by the rotor as the input element, or it can be a corresponding shaft or a similar rotating component, or it can also be a spindle nut or a piston, which is driven through the spindle into a rotary and / or linear movement is offset.

In particular, it is provided that the input element is coupled to the output element. The coupling can take place mechanically and/or magnetically.

If a torque path is discussed here, this essentially describes the path taken by the torque originally generated as torque in order to be actuated, preferably by means of a linear movement of another component, such as a piston, a spindle nut supported with respect to a direction of rotation, or a slave cylinder to do.

The friction device is preferably arranged parallel to a rotating component.

The friction device is preferably arranged parallel to a spindle, in particular a threaded spindle, or parallel to a rotor which drives a spindle, in particular a threaded spindle.

In the embodiment according to the invention, the assembly has a friction device with at least two components that can be rotated relative to one another, which is used in particular to actuate a clutch of a motor vehicle and is at least part of a transmission and/or actuator in the event of a relative rotation of the components, the wrap-spring element that influences the efficiency/friction is arranged, which has at least two radially and axially nested, integrally connected effective regions. As a result, large torque differences can also be generated over a small effective radius. This can be implemented cost-effectively and by means of simple assembly with a small installation space requirement, in particular in the axial direction, and by saving on components.

The inner diameter of the active area of the wrap spring element located radially on the inside is non-rotatably or frictionally connected to an outer diameter of the first component, and the outer diameter of the active area of the wrap spring element located radially on the outside is non-rotatably or non-rotatably connected to an inner diameter of the second component.

Advantageously, the radially inner active area and the radially outer active area of the wrap-spring element are connected to one another in one piece by a transition area.

Further preferred is the formation of the friction device with exactly one element, namely the one wrap spring element with two effective areas. It is a sleeveless friction device which interacts with a first component on the outside and with a second component on the inside, e.g. a spindle, threaded spindle or shaft.

A preferred embodiment provides that the loop spring element/the active areas consist of a spring strip/wire with a rectangular cross section.
The spring band/the wire of the radially outer effective area is wound around the radially inner effective area.

In a particularly advantageous embodiment, the spring strip/wire is rotated/twisted by 90° in the transition area, as a result of which the cross section of the spring strip/wire has a first orientation in the outer active area and a rotated orientation thereto in the inner active area.

A further advantageous embodiment provides that the inner effective area of the wrap-spring element has an interference or oversize/superposition to the first component, which has a small effective radius. Likewise, the outer effective area of the wrap-spring element has an interference with the second component, which has a large effective radius. The interference of the outer effective range to the second component is preferably greater than the interference of the inner effective range to the first component.

In a further advantageous embodiment, the inner active area of the wrap-spring element is equipped with a higher number of turns than the outer active area.

When the assembly with a friction device is used in an actuator, the latter has a gear that can be actuated by a drive, which preferably converts a rotary movement into an axial movement, for example a PWG or a gear of another type, in such a way that a direction-dependent friction is created by the between the first component and the second component is increased slightly against a load when the actuator is driving or significantly increased when the load is driving in order to hold a non-self-locking gear, eg PWG, in the event of a fault/failure of the drive or to reduce or avoid a holding current. At When the friction device according to the invention is used in a PWG, the inner and outer effective areas are arranged between a rotary element of the PWG and a part of the actuator fixed to the housing or between two elements of the PWG that can rotate relative to one another at different speeds.

For example, the wrap-spring element can be integrated between a spindle that can be driven in rotation by the drive (first component) of the PWG and a spring cup that is fixed to the frame/housing (second component) or within the housing of the PWG between two components that can rotate relative to one another.

For example, the friction device designed as a wrap spring element can also be arranged between an outer diameter of a ring gear meshing with the planets of the PWG and an inner diameter of a sleeve encasing the PWG in the area of the ring gear.

By using the wrap spring element with two active areas, one inner and one outer, it is possible to generate low (if possible no) friction in one direction of rotation and high, defined friction in the other direction. This can prevent the load from pushing the actuating device back again when the engine is switched off (self-locking in one direction).

1. 1. Der radial innere Wirkbereich mit dem kleineren Durchmesser ist „fest“ mit dem ersten Bauteil (Welle) verbunden und der äußere Wirkbereich erzeugt eine hohe Reibung zum zweiten Bauteil (Nabe) - eine Selbsthemmung des Aktors wird erzielt.
2. 2. Der radial äußere Wirkbereich „drückt“ mit seinem Außendurchmesser nach außen auf den Innendurchmesser des zweiten Bauteils (Nabe), wodurch der innere Wirkbereich seine Anpresskraft an die Welle reduziert und somit eine geringere Reibung wirkt.

A radial force component in the same direction of the basic radial force can be superimposed in each case by both effective areas of the wrap spring element. There are then two extreme states depending on the direction of rotation:

1. 1. The radially inner effective area with the smaller diameter is "firmly" connected to the first component (shaft) and the outer effective area generates high friction to the second component (hub) - self-locking of the actuator is achieved.
2. 2. The radially outer effective area "pushes" outwards with its outer diameter on the inner diameter of the second component (hub), whereby the inner effective area reduces its contact pressure on the shaft and thus less friction acts.

• 1 eine dreidimensionale Darstellung eines erfindungsgemäßen, einteilig ausgebildeten, Schlingfederelementes mit zwei radial ineinander geschachtelten Wirkbereichen,
• 2 eine Vorderansicht des Schlingfederelementes nach 1,
• 3 eine Seitenansicht des Schlingfederelementes nach 1 in einem Längsschnitt,
• 4 eine Prinzipdarstellung des Schlingfederelementes in Einbaulage,
• 5 einen Längsschnitt des freien Schlingfederelementes nach 4,
• 6 einen Ausschnitt eines Schlingfederelementes, das in einem Übergangsbereich zwischen zwei Wirkbereichen im Querschnitt gedreht/verdrillt ist,
• 7 einen Längsschnitt eines Aktors mit dem erfindungsgemäßen Schlingfederelement.

The invention is explained in more detail below using exemplary embodiments and associated drawings. Show it:

• 1 a three-dimensional representation of a one-piece wrap spring element according to the invention with two radially nested active areas,
• 2 a front view of the wrap spring element 1 ,
• 3 a side view of the wrap spring element 1 in a longitudinal section,
• 4 a schematic representation of the wrap spring element in the installation position,
• 5 a longitudinal section of the free wrap spring element 4 ,
• 6 a section of a wrap spring element that is turned/twisted in cross section in a transition area between two effective areas,
• 7 a longitudinal section of an actuator with the wrap spring element according to the invention.

The 1 shows a three-dimensional representation of a wrap spring element 1 according to the invention with two radially nested effective areas 1.1, 1.2, wherein the effective area 1.1 is provided radially on the inside and the effective area 1.2 is provided radially on the outside. A transition area 1.3 connects the two active areas 1.1 and 1.2 with one another, so that the wrap-spring element 1 is designed in one piece. The wrap spring element 1 preferably consists of a spring band or a wire which is wound radially around the inner effective area 1.1 in the form of the outer active area 1.2.

in the in 2 shown front view as well as in 3 The side view of the wrap-spring element 1 shown clearly shows the radial nesting of the two active areas 1.1, 1.2, with the active area 1.2 located radially on the outside having an outer diameter D2, via which the wrap-spring element 1 comes into contact with an inner diameter of a component arranged radially on the outside, for example a hub or of a ring gear/spring cup (not shown here). The radially inner active area 1.1 has an inner diameter d1, which can be brought into active connection with an outer diameter of a component located radially on the inside, for example a shaft or a spindle (not shown here). Both active areas 1.1, 1.2 are connected to one another in one piece by the transition area 1.3.

In the in the 3 shown longitudinal section of the wrap-spring element 1 is also visible that the cross-section of the spring strip / the wire is rectangular (here square). A spring band/wire with a round cross-section, for example, would have a higher surface pressure on components 2 and 3 (e.g. spindle and spring pot) and thus result in higher wear. The rectangular cross-section of the spring strip has a height h and a width b, where hb is preferred (see Fig. 6 ).

In 4 1 is a schematic representation of the wrap-spring element 1 located in an installed position between the component 2 designed as a shaft and the component 3 designed as a hollow shaft/hub. The shaft 2 and the hub 3 are arranged around a longitudinal axis/axis of rotation A. The radially inner effective area 1.1 is assigned to the shaft 2 and the radially outer effective area 1.2 to the hub 3.

In 5 the wrap-spring element 1 shown in a longitudinal section is located immediately before installation in the in 4 Schematically illustrated components shaft 2 and hub 3. The inner effective area 1.1 has an oversize or an interference a2 to the shaft 2, which has a small effective radius, while the outer effective area 1.2 to the hub 3 (large effective radius) has an interference a1. In the illustrated embodiment, there is preferably a ratio a1 a2. The inner diameter d1 of the inner active area 1.1 and the outer diameter D2 of the outer active area 1.2 shown here illustrate the interferences a1, a2.

The 6 shows a section of the wrap spring element 1 with the effective area 1.2 provided radially on the outside, which is wound around the effective area 1.1 located radially on the inside, and with the transition area 1.3 connecting the two effective areas 1.1, 1.2 in one piece. (For a better representation of the transition from the outer active area 1.2 to the inner active area 1.1, both areas are not shown here radially nested.) The wrap spring element 1 is rotated/twisted in cross section in the transition area 1.3, whereby the cross section of the spring strip/wire in the outer active area 1.2 has a first orientation and in the inner effective area 1.1 has an orientation that is rotated thereto. The spring band of the outer active area 1.2 has a cross section hxb, while the spring band of the inner active area 1.1 has a cross section h*xb*, where h*=b and b*=h. It is also favorable if the inner active area 1.1 has a higher number of turns than the outer active area 1.2 in order to ensure or increase the blocking effect of the active area 1.1.

The 7 shows a preferred application example for the wrap spring element 1 according to the invention. The active area 1.2 of the wrap spring element 1 located on the outside is operatively connected to a spring pot that is arranged radially on the outside and forms the component 3, which in turn is connected in a rotationally fixed manner to a bearing carrier 4 of the spindle bearing that is fixed to the housing or frame. The inner diameter d1 of the inner working area 1.1 surrounds the outer diameter of the spindle 2, while the outer diameter D2 of the outer working area 1.2 is surrounded by the inner diameter of the spring cup 3. The spindle 2 driven by an electric motor (not shown) is accommodated in a housing 5 (PWG sleeve).

• Bei einer Relativdrehung (erste Drehrichtung) zwischen dem ersten Bauteil 2 (Welle/Spindel) und dem zweiten Bauteil 3 (Nabe/Hohlwelle/Federtopf) wird beim Schlie-ßen des inneren Wirkbereichs 1.1 zum Bauteil 2 der Innendurchmesser d1 des Wirkbereichs 1.1 so reduziert, dass dieser drehfest mit dem Außendurchmesser des Bauteils 2 verbunden ist. Durch Mitnahme des über den Übergangsbereich 1.3 mit dem inneren Wirkbereich 1.1 einteilig verbundenen äußeren Wirkbereichs 1.2 wird letzterer in Richtung des Bauteils 3 geöffnet, wodurch eine hohe Reibung generiert und so vorzugsweise eine Selbsthemmung erzeugt wird.

The mode of operation of the assembly with the friction device according to the invention is as follows:

• During a relative rotation (first direction of rotation) between the first component 2 (shaft/spindle) and the second component 3 (hub/hollow shaft/spring cup), when the inner working area 1.1 closes to the component 2, the inner diameter d1 of the working area 1.1 is reduced in such a way that that this is non-rotatably connected to the outer diameter of the component 2. By entraining the outer active area 1.2, which is integrally connected to the inner active area 1.1 via the transition area 1.3, the latter is opened in the direction of the component 3, which generates high friction and thus preferably self-locking.

If, with the opposite relative rotation (second direction of rotation) between component 2 (shaft/spindle) and component 3 (hub/hollow shaft/spring cup), the outer active area 1.2 is closed to component 3, the outer diameter D2 of the outer active area 1.2 increases so that it is pressed against the inner diameter of the component 3 in a torque-proof manner. By entraining the inner working area 1.1, which is integrally connected to the working area 1.2, this is enlarged in its inner diameter d1 in such a way that it slips through on the component 2. Only a small amount of friction is generated.

With the solution according to the invention, an assembly with a friction device is created which also generates large torque differences over a small effective radius. The two effective areas 1.1, 1.2 of the wrap spring element 1 thus form two spring sections with a larger outer diameter D2 for a large braking torque (radially outer effective area 1.2) and a smaller inner diameter d1 for a small braking torque (radially inner effective area 1.1). In this case, there is a small space requirement, particularly in the axial direction, with components being saved as a result of the one-piece design of the wrap-spring element 1 with the two active regions 1.1, 1.2. Thus, the assembly according to the invention is inexpensive and can be realized by means of simple assembly. The friction device with the wrap-spring element 1 assumes the holding function of the electric motor, with a drag torque being realized that is greater than that holding torque is. Depending on the relative direction of rotation, the friction between the components when the actuator is driving against a load is increased only slightly and significantly (by a specific value) when the load is driving, in order to hold, for example, efficiency-optimized, non-self-locking spindle drives in the event of a fault (e.g. in the event of a power failure).

Reference List

1

wrap spring element

1.1

Effective area arranged radially on the inside

1.2

Effective area arranged radially on the outside

1.3

transition area

2

component/shaft/spindle

3

Component/hub/hollow shaft/spring pot

4

bearing carrier

5

Housing/PWG sleeve

A

longitudinal axis

d1

Inner diameter of the inner effective range

D2

Outside diameter of the outer effective range

b

Width of the spring band/wire of the outer effective area

H

Height of the spring band/wire of the outer effective area

b*

Width of the spring band/wire of the inner effective area

H*

Height of the spring band/wire of the inner effective area

Claims (10)

Assembly with a torque-transmitting input element, preferably a rotor, a spindle or the like, with a torque or linear force-transmitting output element, such as a spindle or a spindle nut or the like, the input element and the output element being coupled to one another, in particular for actuation a clutch of a vehicle and wherein the assembly is at least part of a transmission and/or actuator, wherein the torque is transmitted via a torque path from the input element to the output element, wherein a friction device is provided parallel to the torque path, which generates additional friction between the input and output element, wherein the additional friction is generated depending on the direction of rotation of the input and / or output element, characterized in that the friction device comprises at least two relatively rotatable components (2, 3), between which relatively rotatable ble components (2, 3), a wrap spring element (1) that influences the efficiency/friction when the components (2, 3) rotate relative to each other is arranged, which has at least two radially and axially nested, integrally connected active areas (1.1, 1.2) having. assembly claim 1 , characterized in that the radially inner active area (1.1) of the wrap-spring element (1) with its inner diameter (d1) is non-rotatably or frictionally engaged with an outer diameter of the first component (2) and the radially outer active area (1.2) of the wrap-spring element (1) is operatively connected with its outer diameter (D2) to an inner diameter of the second component (3) in a frictional or non-rotatable manner. assembly claim 1 or 2 , characterized in that the radially inner active area (1.1) and the radially outer active area (1.2) are connected to one another in one piece by a transition area (1.3). Assembly according to one of Claims 1 until 3 , characterized in that the loop spring element (1)/the active areas (1.1, 1.2) consist of a spring strip/wire with a rectangular cross section. assembly claim 4 , characterized in that the spring band/the wire is turned/twisted by 90° in the transition area (1.3) and thus the cross section of the spring band/wire in the outer active area (1.2) has a first orientation and in the inner active area (1.1) a rotated one has orientation. Assembly according to one of Claims 1 until 5 , characterized in that the radially outer active area (1.2) is wound around the radially inner active area (1.1). Assembly according to one of Claims 1 until 6 , characterized in that the inner effective area (1.1) of the wrap-spring element (1) has an interference (a2) to the first component (2), which has a small effective radius. Assembly according to one of Claims 1 until 7 , characterized in that the outer effective area (1.2) of the wrap-spring element (1) has an interference (a1) with the second component (3), which has a large effective radius. assembly claim 7 or 8th , characterized in that the interference (a1) of the outer active area (1.2) to the second component (3) is greater than the interference (a2) of the inner active area (1.1) to the first component (2). Assembly according to one of claims 2 until 10 , characterized in that the inner active area (1.1) of the wrap spring element (1) has a higher number of turns than the outer active area (1.2).

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