WO2009141265A1

WO2009141265A1 - Actuator comprising a load torque lock

Info

Publication number: WO2009141265A1
Application number: PCT/EP2009/055859
Authority: WO
Inventors: Ulrich Grau; Manfred Kraus; Harald Hochmuth; Wolfgang Reiik
Original assignee: Schaeffler Kg
Priority date: 2008-05-23
Filing date: 2009-05-14
Publication date: 2009-11-26
Also published as: DE102008024910A1

Abstract

The invention relates to an actuator comprising a motor (01) and a take-off section (10) for connecting to a control element and a load torque lock for blocking the take-of section (10) to avoid undesired control movements. The invention is characterized in that the load torque lock comprises a coil spring (18).

Description

Actuator with a load torque lock

The invention relates to an actuator with a motor and a driven part for connection to an actuating element and with a load torque lock for blocking the driven part to avoid unwanted actuating movements.

Generic actuators can be used for example in motor vehicles in the chassis. Thus, in each case an actuator can be assigned to the individual wheels in a suspension, which is independently controllable and performs the desired adjustment of the body-side control element of the wheel guide.

A suspension for motor vehicles can be taken from DE 100 11 142 A1, in which a wheel-guiding element of a suspension designed as a link or adjusting element is connected at one end to a wheel carrier and is articulated at its second end by an actuator. The actuator comprises an electric motor and a ball screw, the threaded spindle is designed as a driven member which articulates the wheel guide via a hinge. Such actuators take over safety-relevant functions.

In such applications, there is a requirement that the articulated chassis parts in the de-energized state of the actuator perform no unwanted positioning movements, but are held in the last set position. It should also be ensured that external forces that are fed backwards into the actuator via the chassis are safely absorbed without the actuator performing undesired positioning movements as a result of these external forces.

In DE 10 2005 023 250 A1 an actuator with a locking mechanism is described, which blocks the output part of the actuator, when the driving force of the actuator at the output part is smaller than an outer external force acting on the output part. The actuator can be used, for example, for active adjustment. ment of the camber of a wheel of a motor vehicle can be used. From the outside in the wheel initiated shocks are forwarded only to the output part of the actuator. An introduction of these forces in the actuator to the motor is prevented because the driven part is blocked by the locking mechanism. According to a preferred embodiment, the locking mechanism is designed as a switchable Klemmrollengesperre.

The problem with actuators - in which the freewheel is designed as a Klemmrollengesperre - is that with dynamic adjustment of the actuator in the freewheel the so-called stick-slip effect can occur. Stick-slip effect refers to the jolting of mutually moving solids. At the same time, damped-coupled surface parts exert a fast sequence of movements of adhesion, distortion, separation and slipping. In generic actuators, this effect occurs when the lock closes faster than the engine can open it.

This leads to the excitation of vibrations emitted by a resonant surface as noise. In addition to occurring noise, it also leads to higher wear. Therefore, the stick-slip effect should be avoided or reduced as much as possible.

For a long time, it has been known to replace a freewheel with Klemmgesperre by a wrap spring freewheel. For example, DE 75 37 010 discloses a wrap spring freewheel in which two identical wrap spring clutches are used for clockwise and counterclockwise rotation. The wrap springs are each mounted with a bent end in a groove of the drive hub and hung with the other bent end in a rotatable outer sleeve, which is fixedly connected to the output shaft. The wrap spring freewheel described can be used for example in chain-driven child vehicles with freewheel in the forward and backward direction. WO 2003/029680 A1 includes a drive unit with wrap spring brake, in which a braking or blocking effect is achieved by means of a coil acting under bias against a starting member wrap. In this way, a rotation of the driven or the drive shaft is prevented in non-driven drive shaft and acting on the output shaft loads.

Such drive units are used for example as tubular motors for the electric drive of a winding shaft of a roller shutter or the like. Due to the blocking effect prevents the roller shutter unwinds due to its own weight coupled to the drive shaft winding shaft and the shutter closes eigentätig.

In such drive units, it may happen during the lowering process that the drive shaft or the output shaft overhauled the load to be lowered, whereby the wrap spring acts due to its bias against the starting member and the output shaft locks. This can lead to a constant change between loosening and locking between coil spring and starting member.

In order to avoid or reduce this stick-slip effect, it is proposed in WO 2003/029680 A1 to provide the starting member with a radially outward widening. As a result, when relaxing the wrap spring acts a larger contact surface of the wrap spring against the inner surface of the starting member, creating a softer braking behavior is generated and the stick-slip effect can be significantly reduced.

Furthermore, it is known from the use of wrap springs in manual window regulators that they work stick-slip-free.

The object of the present invention, starting from DE 10 2005 023 250 A1, is therefore to provide an actuator with a load moment lock, in which a stick-slip effect is to be effectively avoided even with dynamic adjustment of the actuator. Weight- Torque lock should be easy to install in the actuator and cause only a small additional cost.

To achieve the object according to the invention, an actuator according to the appended claim 1 is used.

An inventive actuator is characterized in that a load torque lock is formed by a wrap spring, which is provided between a stationary housing of the actuator and a drive part. The wrap is oversize, d. H. arranged with a press fit on a ring connected to the housing and has at its two ends outwardly bent driver elements which cooperate with a provided on a drive driver, so that upon rotation of the drive first the wrap spring is released and then the drive part can rotate freely.

A significant advantage of the solution according to the invention is the fact that by using a load torque lock based on a wrap spring even with dynamic adjustment of the freewheel essentially no stick-slip effect and associated with this effect negative side effects occur.

The load torque lock can be easily integrated into the actuator.

A wrap spring freewheel used according to the invention comprises only a single wrap spring. Compared to previously known freewheels with Klemmroll- engesperre a wrap spring freewheel is therefore much simpler structure, which can save costs and not least also significantly reduces the maintenance effort.

According to a preferred embodiment, the actuator comprises a motor and a ball screw with one connected to a driven part Threaded spindle and a driven by the motor spindle nut as a driving part.

In a particularly favorable embodiment, the spindle nut is arranged circumferentially fend a ring, which is rigidly connected to a, for receiving the motor, the load torque lock and the ball screw drive housing.

The wrap spring is arranged between the ring and the spindle nut. The wrap spring contracts in a locking position due to the friction in the winding direction and thus blocks the spindle nut.

In a release position, the wrap spring is opened against its winding direction and thus allows rotation of the spindle nut.

If the drive is the motor, the wrap spring is opened against its winding direction. The spindle nut can now rotate freely.

In the event that there is no drive from the motor, for example in the de-energized state, it is necessary to fix the position of the spindle nut. For this purpose, it is expedient if the wrap with a slight oversize sitting directly on the ring and presses against the outer diameter of the spindle nut. In the event that the spindle nut, for example, due to the application of external forces, wants to rotate, the wrap spring contracts due to the applied friction in the winding direction and thus blocks the spindle nut. In this way, unwanted positioning movements can be effectively avoided.

In an advantageous embodiment, the threaded spindle is formed integrally with the driven part of the actuator. This results in both manufacturing technology and mounting advantages. According to a further advantageous embodiment, a bellows is attached to the housing and the driven part, which encloses the threaded spindle. The bellows is tight against the housing and the driven part. The bellows can prevent the ingress of contaminants into the ball screw drive.

The use of the actuator according to the invention in an active suspension link of a motor vehicle, in particular for adjusting the camber, has proved to be advantageous. Due to its high reliability, the actuator according to the invention is particularly suitable for such safety-related applications. However, it should not be limited to the applications mentioned, other applications are quite possible.

Further advantages, details and developments of the present invention will become apparent from the following description of a preferred embodiment with reference to the drawings. Show it:

1 shows an actuator according to the invention in a longitudinal sectional view;

2 shows a wrap spring freewheel in a front view and a sectional view;

3 is an assembly drawing of the wrap spring freewheel according to FIG. 2.

Fig. 1 shows an actuator according to the invention in a longitudinal sectional view. The actuator according to the invention comprises a motor designed as an electric motor 01 with a stator 02 and a rotor 03. The rotor 03 also serves as a motor shaft. The electric motor 01 is arranged within a housing 04.

The actuator according to the invention further comprises a trained as a ball screw gear with a spindle nut 06, which acts as a drive part, and a threaded spindle 07 as a driven part. The spindle nut 06 is mounted in the housing 04 via a roller bearing 08.

The threaded spindle 07 is designed in one piece with the driven part 10 in the embodiment shown. Between the spindle nut 06 and the threaded spindle 07 balls 11 are arranged, which roll on raceways 12, 13 of the spindle nut 06 and the threaded spindle 07 and rotate in endless ball tracks. A rotation of the spindle nut 06 is converted into a translation of the threaded spindle 07.

In the embodiment shown in FIG. 1, the threaded spindle 07 or the driven part 10 projects beyond the housing 04 on the front side (shown on the right). In order to prevent ingress of contaminants in the ball screw, in particular in the threaded spindle 07, the actuator is provided on this side with a bellows 15. One end of the bellows 15 is attached to the output part 10 opposite end face of the housing 04. The other end of the bellows 15 is connected to the output member 10. The bellows 15 is close to the housing 04 and the output member 10 at. As a result, the threaded spindle 07 is completely sealed to the outside and can not pollute.

The spindle nut 06 encompassing a ring 17 is arranged with a U-shaped profile, which is rigidly connected to the housing 04.

On the ring 17 a wrap spring 18 is arranged. Between wrap spring 18 and ring 14 is an interference fit.

Based on Figures 2 and 3, the operation of the wrap spring freewheel will be explained. Fig. 2 shows in Figure a) a front view and in Figure b) is a sectional view along the section line AA in Figure a). In Fig. 3 is an assembly drawing of the wrap spring freewheel is shown. The actuator works as follows: To trigger a setting process, the electric motor 01 is actuated. About a driver 20 (see FIGS. 2 and 3) of the electric motor 01, the wrap spring 18 is opened against its winding direction. For this purpose, two outwardly bent ends 21 are formed on the wrap spring 18. When rotating the rotor and thus the output part of the motor 01, the ends 21 are moved depending on the direction of rotation of the motor in the direction of the rotary arrows 22, 23, whereby the wrap spring 18 is opened and thereby lifts off the ring 17. The spindle nut 06 now has enough space to turn, driven by the driver 20 to rotate. For this purpose, the spindle nut 06 has two, partially in the circumferential direction extending stop segments 24. The wrap 18 rotates at angetriebner spindle nut 06 with. The rotation of the spindle nut 06 is converted into a translation of the threaded spindle 07. Depending on the direction of rotation, the threaded spindle 07 is extended out of the housing 04 or retracted into the housing 04.

In the event that the electric motor 01 is de-energized or if, for example due to potholes, large impact forces in the longitudinal direction of the driven part 10 are introduced into the ball screw, it must be ensured that the spindle nut 06 is not rotated, and thereby unwanted positioning movements can be caused.

This is achieved in that the wrap spring 18 is seated with slight oversize on the ring 17 of the spindle nut 06, which presses against the inner diameter 26 of the spindle nut 18. If the spindle nut 06 now wants to rotate, the wrap spring 18 contracts due to the friction occurring in the winding direction and thereby blocks the spindle nut 06.

In Figure a) of Fig. 2, the closed position of the wrap spring 18 is shown, while Figure b) represents the open position of the wrap spring freewheel.

The opening of the wrap spring 18 is independent of the direction of rotation of the motor right or left. LIST OF REFERENCE NUMBERS

01 electric motor

02 stator 03 rotor

04 housing

05 -

06 spindle nut

07 Threaded spindle 08 Rolling bearings

09 -

10 stripping section

11 balls of the ball screw

12 Track of the spindle nut 13 Track of the threaded spindle

14 -

15 bellows

16 -

17 ring 18 wrap spring

19 -

20 drivers

21 bent end

22 Direction of rotation 23 Direction of rotation

24 stop segment

25 -

26 inner diameter

Claims

claims

1. Actuator with a motor (01) and a Abthebsteil (10) for connection to an actuator and a load torque lock for blocking the output member (10) to avoid unwanted positioning movements, characterized in that the load torque lock by a wrap spring (18) is.

2. Actuator according to claim 1, characterized in that it comprises a ball screw with a driven part (10) connected to the threaded spindle (07) and one of the motor (01) driven spindle nut (06).

3. Actuator according to claim 2, characterized in that it comprises a housing (04) for receiving the motor (01), the load torque lock and the ball screw.

4. Actuator according to claim 2 or 3, characterized in that opposite to the spindle nut (06) with the housing (04) rigidly connected ring (17) is arranged, that the wrap spring (18) between the ring (17) and the spindle nut (06) is arranged, wherein the wrap spring (18) in a blocking position, the spindle nut (06) blocks and in a release position, a rotation of the spindle nut (06) allows.

5. Actuator according to one of claims 2 to 4, characterized in that the wrap spring (18) with oversize on the outer diameter of the spindle nut (06) sits.

6. Actuator according to one of claims 2 to 5, characterized in that the threaded spindle (07) is formed integrally with the driven part (10).

7. Actuator according to one of claims 2 to 6, characterized in that it comprises a on the housing (04) and on the driven part (10) sealingly mounted bellows (15), wherein the bellows (15) surrounds the threaded spindle (07) ,

8. Actuator according to one of claims 1 to 7, characterized in that it is part of an active suspension arm of a motor vehicle, in particular for adjusting a camber.