DE102015204588A1 - Actuator with a friction device using a wrap spring element and method for producing the wrap spring element - Google Patents

Abstract

The invention relates to an actuator with a friction device and with at least two relatively rotatable components, in particular for the actuation of a clutch of a motor vehicle, wherein between the relatively rotatable components a in a relative rotation of the components, the efficiency / the friction influencing Schlingfederelement is arranged, which has at least two one-piece interconnected effective areas, according to the invention, the wrap spring element is wound from a rectangular wire with a constant wire cross-section, and the wrap spring is at least partially reduced by at least one machining operation in its wire cross-section.

Description

The invention relates to an actuator with a friction device using a Schlingfederelementes and a method for producing the Schlingfederelementes according to the preamble of the 1st and 9th claim, wherein the friction device comprises at least two relatively rotatable components and the actuator in particular for the actuation of a clutch Motor vehicle is used.

Actuators are used for example for actuating a clutch of a vehicle and 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. As PWG actuator (PWG = Planetenwälzgewindsspindeltrieb), hydraulic slave cylinder, etc ..

Planetenwälzgewindespindeltriebe (PWG) are formed from a spindle, a spindle nut and between them arranged over the circumference, received in a planet carrier Planetenwälzkörpern. Here, the spindle, spindle nut and Planetenwälzkörper on profiling to transmit a rotational movement between the spindle and spindle nut, wherein one of the components - spindle or spindle nut - rotatably driven and the other component in a rotationally fixed arrangement along the longitudinal axis of the spindle by one of the set translation corresponding Axialweg is relocated. Here, the Planetenwälzkörper two different profile sections, which mesh on the one hand with the spindle and on the other hand with the spindle nut, the profile sections on the Planetenwälzkörper grooved and the other profile sections on the Planetenwälzkörper are generally grooved and depending on the embodiment, a complementary threaded portion on the spindle or the spindle nut and according to the groove portion is arranged on the other component. As a result, compared to a direct recording of the spindle on the spindle nut translations are achieved with which per spindle rotation with less feed a higher force is possible.

From the EP 320 621 A1 For example, a PWG is known in which the spindle has a thread and the spindle nut grooves, on which roll each planetary rolling elements by means of correspondingly complementarily formed profile sections. Here, the axially fixed and rotatably driven, for example by an electric motor spindle relative to the rotatably mounted spindle nut is rotated, so that the spindle nut is forcibly displaced axially and by the frictional rolling of the planetary body in the grooves of the spindle nut. This results in the Axialweg the spindle nut proportional to the speed of the spindle movement. To this end, according to planetary gears of the planet carrier rotates with the planetary rollers at half speed or another ratio, depending on the design of the diameter of the rotating component, namely spindle or spindle nut.

The DE 10 2010 047 800 A1 shows an application of a Planetenwälzgetriebes, in which designed as a piston of a master cylinder Aktorteil a Hydrostataktors axially fixed to the rotatably and axially displaceably arranged spindle is coupled, wherein the axially fixed spindle nut is rotationally driven by an electric motor, so that upon rotation of the spindle nut spindle and Spindle nut are shifted against each other along the Axialwegs. Since the piston accommodating and forming a pressure chamber with this cylinder housing is fixed and the spindle nut is axially supported on this, the piston builds depending on the rotary drive of the spindle nut pressure, for example for actuation of automotive components such as brakes, friction clutch and the like. It is particularly desirable for friction clutches to quickly bridge a clearance with low load request by means of a high pitch and be able to apply high loads with an electric motor with low power in the effective range of the friction clutch by means of a small slope.

In example, driven by an electric motor efficiency-optimized spindle drives (eg. PWG), especially in actuators, such as hydrostatic clutch actuators (Hydrostatic Clutch Actuator - abbreviated HCA), which work against a load, such as a clutch characteristic, there is a problem that when a required holding a Position holding current and thus a holding torque in the electric motor is required because the spindle drive (eg in a PWG) is not self-locking. In a PWG in a HCA with rotatable ring gear nut with driven spindle on which the axial movement (relative to the spindle) is tapped, takes place in an ideal rolling movement (as in a toothed planetary gear / no slip) an additional reduction of the spindle pitch, this is varied by of spindle and / or planetary roller diameter within limits freely selectable. A decisive disadvantage of such actuators is that they require a permanent holding current or, in the event of a power failure / fault (eg cable break, plug drop), the position can not be maintained. If the clutch is pressed by the actuator, then there is a great danger that the clutch will close unintentionally. It is also known the use of wrap springs, for example for clutches. A The wrap spring usually consists of a metallic wire which extends in several turns around a cylindrical part. Between this spring and the cylindrical part a friction force acts upon rotation of the cylindrical part. This can be influenced by tightening or releasing the wrap spring.

A wrap spring clutch usually consists of a wound on a shaft or a cylindrical body coil spring, which is fixed on one side to the drive. The entrainment effect is based on the fact that the driving torque with each turn amplified by the friction and adds up. This increases because of the wrap at the same time the friction causing this force. In the opposite direction occurs only a slight friction - the spring slightly increases its diameter, but does not wrap. Due to their friction remaining in free-running operation, the wrap spring is also used for slipping clutches. As a freewheeling element, it has a self-reinforcing (blocking) effect in one direction and a cancellation of this function in the other direction, wherein the spring only has to be rotated against its basic friction.

From the publication DE 10 2007 047 394 A1 For example, a torsional vibration damper is known which has at least two counter to the action of a damping device with circumferentially acting energy storage to each other rotatable parts, one of which is connectable to a prime mover and the other with a driven shaft, wherein between the two parts additionally with the Damping device is provided in series connected torque limiter, which is effective at least in one of the relative rotational directions between the two parts and at least one Schlingenfederkupplung includes, which acts upon reaching a predetermined angle of rotation between the two parts as a freewheel and at least one loop spring element comprises. This solution is characterized in that at least one end of the loop spring element is non-rotatably connected to a ring element which has support regions for the energy storage devices acting in the circumferential direction and / or activation regions for the freewheeling effect.

In a not yet published technical solution of the applicant, an assembly with a friction device with at least two mutually rotatable components, in particular for the actuation of a clutch of a vehicle, proposed in which between the relatively rotatable components at a relative rotation of the components, the efficiency / the friction influencing coil spring is arranged. At least partially, the helical spring forms a wrap spring, which may be a simple wrap spring, a double wrap spring or a loop torsion spring. The double-loop spring described here has two effective regions, which are arranged axially one behind the other.

Another not yet published technical solution of the applicant also describes an assembly with a friction device with at least two relatively rotatable components, between which a wrap spring is arranged, which has two coupled Schlingfederbereiche, wherein in a relative rotation of the components in one direction of rotation a small Friction and in the other direction a high friction can be generated. In this case, the coupling of the two Schlingfederbereiche by a connector which is formed as a sleeve or a ring and the two radially interleaved Schlingfederbereiche positioned to each other, such that torques from the first Schlingfederbereich on the second Schlingfederbereich and vice versa are transferable. The two Schlingfederbereiche be realized here 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 in this embodiment by the different cross sections / diameter of the inner and outer spring. However, there is the disadvantage here that assembly is made more difficult by the multi-part construction of the wrap spring and the costs increase due to the use of the connecting element connecting the two wrap spring regions.

In another not yet published technical solution of the applicant an assembly with a friction device and at least two relatively rotatable components is described, wherein between the relatively rotatable components arranged at a relative rotation of the components, the efficiency / the friction Schlingfederelement arranged, which at least has two radially nested, one-piece interconnected, effective areas. The radially inwardly located effective region of the wrap spring element is non-rotatably or frictionally engaged with an inner diameter of the second component with its inner diameter rotationally or frictionally engaged with an outer diameter of the first component and the radially outwardly active region of the Schlingfederelementes with its outer diameter frictionally engaged or non-rotatably.

The use of a common wire for both spring sections results in the representation of a high friction torque, a radially high and axially short wire cross-section. For tolerance-related realistic coverage of the Low friction loop spring section results in an unintentionally high friction torque in this area.

The object of the present invention is to develop an actuator with a friction device using a wrap spring element and a method for producing the wrap spring element, wherein the wrap spring has a wrap spring geometry, which despite using a wire with constant over its length cross section in the region of low friction despite tolerance-insensitive (and thus relatively large) overlap with the shaft, only a small frictional torque is generated.

The object is solved by the characterizing features of the first and ninth patent claim. Advantageous embodiments emerge from the subclaims.

The actuator with a friction device has at least one wrap spring element and at least two relatively rotatable components, and is used in particular for the actuation of a clutch of a motor vehicle, wherein between the relatively rotatable components in a relative rotation of the components the efficiency / friction influencing Schlingfederelement is arranged, which has at least two interconnected effective areas, wherein the wrap spring element according to the invention is wound from a wire with a constant wire cross section and at least partially reduced by at least one machining operation in its wire cross section.

The wire cross section of the wrap spring element is preferably rectangular or square and the wire cross-section is reduced at least over the length of an effective range by at least one cutting and / or non-cutting machining operation from an output cross section to an end cross section.

As an alternative to a rectangular wire, it is also possible to choose a wire with a round cross section or another arbitrary cross section, which is at least partially reduced in its cross section by at least one machining operation.

The wire cross section of the wrap spring is reduced at least in some areas over a length range by machining in the form of grinding, milling or turning or a combination of the aforementioned machining operations. Alternatively, it is also possible to use an electrochemical removal method for reducing the wire cross section, which may also be combined with a machining operation that takes place before or after.

The wrap spring element is advantageously wound in one piece and has at least two effective areas, which are at least two axially separate effective areas with different friction moments. A first effective range causes a lower friction torque and a second effective range a higher friction torque.

In particular, the wrap spring element is wound in the second effective range for the higher friction torque to a larger diameter, as in the first effective range for the lower friction torque.

It has proved to be particularly favorable when the wrap spring element has a larger number of turns / windings in the first effective range for the lower friction torque than in the second effective range for the higher friction torque.

In one embodiment, the wire cross-section is selected with respect to the requirements for the high friction torque and the spring is wound in one piece over its entire length. In order to reduce this to a necessary minimum in the region of the low frictional torque, a maximum of many windings are wound for this purpose in order to lock securely when the large frictional torque is to act, and the wire cross section is reduced by a downstream processing operation.

In an advantageous embodiment, the cross section of the wrap spring element is reduced in the first effective range for the lower friction torque at its outer and / or inner diameter.

The loop spring resulting from the machining process is then comparable to a loop spring wound from a wire of variable cross-section, which, however, is considerably more complex in terms of production technology and therefore not to be preferred.

Alternatively, both friction regions of the wrap spring can be nested radially and the inner wrap spring region can be reduced in cross-section preferably at its inner diameter.

• a. Wickeln des Schlingfederelementes aus einem Draht mit konstantem Querschnitt, wobei das Schlingfederelement im Bereich für das höhere Reibmoment auf einen größeren Durchmesser gewickelt wird als im Bereich für das geringere Reibmoment,
• b. bereichsweise Reduzieren des Querschnittes des Schlingfederelementes durch wenigstens einen weiteren Bearbeitungsvorgang.

Also according to the invention is a method for producing a wire wound loop spring element, comprising the following steps:

• a. Winding the wrap spring element of a wire with a constant cross section, wherein the wrap spring element in the range for the higher friction torque to a larger diameter is wound as in the area for the lower friction torque,
• b. partially reducing the cross section of the wrap spring element by at least one further machining operation.

Preferably, the wrap spring element is first wound from a wire having a rectangular wire cross section and then the wire cross section is reduced at least over the length of an effective range of Schlingfederelementes by at least one cutting and / or non-cutting machining operation from an initial cross section to an end cross section, in particular a second effective range for a higher Friction torque is wound to a larger diameter than a first effective range for the lower friction torque and that the first effective range for the lower friction torque at its outer and / or inner diameter to reduce the wire cross-section is processed by at least one cutting and / or non-cutting machining operation.

Roof of the reduction of the cross section through the machining on the outer and / or inner diameter, in addition, at least the machined region can be processed by means of a beam processing method. This can e.g. a beam processing by means of sand or glass balls or other suitable materials, by which any burr that has arisen during the machining, is removed and / or solidification of the surface is realized.

The invention will be explained in more detail with reference to embodiments and accompanying drawings, without being limited to these. Showing:

1 an inventive Schlingfederelement 1 with at the outer diameter of the first effective range 6 for the lower friction torque abraded cross section,

2 an inventive Schlingfederelement 1 with at the inner diameter of the first effective range 6 For the lower friction torque abraded cross section.

In the 1 and 2 is an inventive Schlingfederelement 1 shown, which is a Innenreibfläche 2 having, which cooperates with an outer diameter of a friction partner, not shown. It is also a sanded area 3 present, which extends over the length of the internal friction surface. It is still a Außenreibfläche 4 present, which in the axial direction substantially to the Innenreibfläche 2 connects and cooperates with the inner diameter of another friction partner, not shown. The wrap spring element 1 is made of a wire with rectangular wire cross-section wound in one piece. This will be a first effective area 6 which extends axially along the internal friction surface 2 extends and a second effective range 7 that extends axially along the external friction surface 4 extends, formed. In the second effective range 7 is the output cross section 1A represented the used rectangular wire. This was the Schlingfederelement 1 wound over its entire length, but the output outer diameter D6a of the first effective range 6 smaller wound than the outer diameter D7 of the second effective range 7 , Since the output cross section 1A is the same, there is an initial inner diameter d6a of the first effective range 6 , which is smaller than the inner diameter d7 of the second effective range 7 , In the first effective range 6 to reduce the cross section was in the variant after 1 in the first effective range 6 a sanded area 3 generated at the outer diameter, whereby the output outer diameter D6a has been reduced to the final outer diameter D6b. This has been in the first effective range 6 the wire cross section on an end cross section 1B reduced.

In the variant after 2 is the abraded area 3 on the inner circumference of the first effective range 7 because the initial inner diameter d6a was increased to a final inner diameter d6b by a preferably mechanical working method.

In both variants, the first effective range 6 for a lower friction torque and the second effective range 7 designed for a higher friction torque.

LIST OF REFERENCE NUMBERS

1

wrap

1A

 Output section

1B

 final section

2

inner friction

3

abraded area

4

Außenreibfläche

5

Original section

6

 Low frictional torque range / first effective range

D6a

 Output outer diameter of the first effective range

D6A

 Starting inner diameter of the first effective range

D6b

End outside diameter of the first effective range

D6B

 End inside diameter of the first effective range

7

 High friction torque range / second effective range

D7

 Outer diameter of the second effective range

d7

 Inner diameter of the second effective range

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 320621 A1 [0004]
• DE 102010047800 A1 [0005]
• DE 102007047394 A1 [0008]

Claims (10)

Actuator with a friction device using a wrap spring element ( 1 ), wherein the friction device comprises at least two relatively rotatable components and the actuator is used in particular for the actuation of a clutch of a motor vehicle, wherein between the relatively rotatable components relative to a relative rotation of the components the efficiency / the friction influencing Schlingfederelement ( 1 ), which has at least two interconnected effective areas ( 6 . 7 ), characterized in that the wrap spring element ( 1 ) is wound from a wire with a constant wire cross section and is at least partially reduced by at least one machining operation in its wire cross section. Actuator according to claim 1, characterized in that the wire cross section of the wrap spring element ( 1 ) is rectangular and that the wire cross-section at least over the length of an effective range ( 6 . 7 ) by at least one machining and / or non-cutting machining operation of an output cross-section ( 1A ) to an end cross-section ( 1B ) is reduced. Actuator according to claim 1 or 2, characterized in that the wire cross section of the wrap spring is at least partially reduced by a machining in the form of grinding or milling or turning or a combination of the aforementioned machining operations. Actuator according to claim 2, characterized in that a non-cutting machining of the wrap spring element ( 1 ) by an electrochemical process. Actuator according to one of claims 1 to 4, characterized in that the wrap spring element ( 1 ) is wound in one piece. Actuator according to one of claims 1 to 5, characterized in that the first active regions ( 6 ) and the second effective range ( 7 ) at least two axially separate regions with different friction moments ( 6 . 7 ), where the first effective range ( 6 ) a lower friction torque and the second effective range ( 7 ) cause a higher friction torque. Actuator according to one of claims 1 to 6, characterized in that - the wrap spring element ( 1 ) in the second effective range ( 7 ) is wound to a larger diameter than in the region for the lower friction torque ( 6 ) and / or - that the wrap spring element ( 1 ) in the first effective range ( 6 ) has a larger number of windings for the lower friction torque than in the second effective range ( 7 ) for the higher friction torque. Actuator according to one of claims 1 to 7, characterized in that the wrap spring element ( 1 ) in its first effective range ( 6 ) is reduced for the lower friction torque at its outer and / or inner diameter. Method for producing a wrap spring element ( 1 ) for an actuator according to claim 1, wherein the wrap spring element is wound from wire, characterized in that: a. the wrap spring element ( 1 ) is first wound from a wire with a constant wire cross-section and then b. at least partially, the wire cross-section of the wrap spring element ( 1 ) is reduced by at least one machining operation. A method according to claim 9, characterized in that - the wrap spring element ( 1 ) is wound from a wire with a rectangular wire cross-section and - that the wire cross-section at least over the length of an effective range ( 6 . 7 ) of the wrap spring element ( 1 ) by at least one machining and / or non-cutting machining operation of an output cross-section ( 1A ) to an end cross-section ( 1B ), in particular a second effective range ( 7 ) is wound for a higher friction torque to a larger diameter than a first effective range ( 6 ) for the lower friction torque and that the first effective range ( 6 ) is processed for the lower friction torque at its outer and / or inner diameter for reducing the wire cross-section by at least one cutting and / or non-cutting machining operation.

Images