WO2014037199A1

WO2014037199A1 - Reducing gear unit, particularly for an adjusting device of a motor vehicle

Info

Publication number: WO2014037199A1
Application number: PCT/EP2013/067052
Authority: WO
Inventors: Christian Sturm
Original assignee: C. Rob. Hammerstein Gmbh & Co. Kg
Priority date: 2012-09-06
Filing date: 2013-08-15
Publication date: 2014-03-13
Also published as: DE102012022788B3; DE102012022788B8

Abstract

The invention relates to a reducing gear unit (10) with a housing (15) and an input shaft (20) rotatable relative to the housing (15) and connected via a gear unit to an output shaft (40) rotatably mounted in the housing (15). A friction element (25) is connected for conjoint rotation to a gear element of the reducing gear unit (10) rotatable relative to the housing (15) and cooperates with a brake element (50). The magnitude of the moment of friction between the friction element (25) and the brake element (50) is dependent on the rotational direction of the input shaft (20). According to the invention, the brake element (50) comprises a thread (54), which cooperates with a thread (16) on the housing (15), and the brake element (54) is seated rotatably and axially movably in the housing (15).

Description

Reduction gear, in particular for an adjusting device of a

Motor vehicle seat

The invention relates to a reduction gear, in particular for a

Adjustment device of a motor vehicle seat, having the features of the preamble of claim 1. State of the art

From the prior art reduction gears are known, which are driven by an electric motor, and whose output shaft serving as the output is provided with a wrap spring brake, which is released upon actuation of the electric motor. Such reduction gears have the disadvantage that

In particular when driving a height adjustment device of a motor vehicle seat different adjustment speeds in the upward and downward direction occur because the electric motor due to the force acting on the seat weight forces in the upward direction must deliver a significantly higher performance than in

Downward direction. A necessary axial play compensation in the engine also causes clacking noises when changing the direction of rotation. In order to avoid an undesired adjustment, the toothing between a worm and a worm wheel of the reduction gear is designed in particular such that it lies clearly in the region of self-locking, which considerably reduces the efficiency of the reduction gear. From DE 196 28 520 A1 discloses a self-locking gear with a mounted in a bush-like friction element drive shaft is known. The friction element is slotted in the axial direction and generates a dependent of the direction of rotation of the drive shaft friction force on the drive shaft in the manner of a self-energizing brake.

DE 200 12 830 U1 discloses a helical gear transmission with a brake acting only in one direction of rotation, which is actuated by an axial force of helical spur gears. For the two directions of rotation different, different from zero, braking torques are not feasible.

A linear drive with a non-self-locking screw spindle, which is rotatable in both directions of rotation and with a drive nut, which is screwed axially movable on the screw, is known from EP 0 662 573 A1. A drive of the screw spindle comprises a coil spring, which is fastened with one end in a drive housing, and which surrounds the screw spindle with several turns. In one direction of rotation, the turns of the coil spring tighten, so that it acts as a brake.

A seat adjuster for a motor vehicle seat with an effective in only one direction braking device to prevent chattering noise is known from DE 31 02 402 C2.

task

The invention is based on the object to improve a reduction gear of the type mentioned, in particular with simple means to adjust the adjustment speeds of a drive a height adjustment of a motor vehicle seat in the upward and downward direction by different, rotational direction-dependent braking moments, to avoid noise and running with a To reduce the reduction gear connected adjusting device of a motor vehicle seat with swinging seat load. solution

This object is achieved according to the invention by a reduction gear with the features mentioned in claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

Characterized in that the brake element comprises a thread which cooperates with a thread of the housing, and the brake element - due to

Thread pairing is at least slightly - rotatably mounted and axially movable in the housing, the brake element can be guided by simple means and a reproducible force, for example by per se known energy storage, against the friction element and in particular biased against this.

By the mounting of the brake element in the described thread pairing of the thread of the brake element and the thread of the housing, a braking effect can be generated, which is dependent on the direction of rotation of the cooperating with the braking element friction element by the

Brake element is slightly rotated in the thread pairing due to the braking action between the brake element and the friction element and thereby occurs at a reversal of rotation relative rotation between the brake element and the friction element, a change in the contact force between the brake element and friction element. The braking effect can be adjusted inter alia by the choice of thread pitch. Preferably, the brake member is rotatably mounted and axially movable in the direction of the input shaft of the reduction gear and biased. The friction element is then preferably secured to a brake element facing the end of the input shaft, in particular rotatably secured. In a seat height adjustment, the reduction gear according to the invention is designed so that in a direction of adjustment of the seat up the smaller friction torque and in the adjustment down the larger Frictional torque is generated. Furthermore, the friction torque avoids a professional in the art as drains designated, unintentional adjustment of the adjusting device with oscillating load. The threads of the brake element and the housing are preferably designed by correspondingly large thread pitches so that the

Thread pairing is outside the self-locking, so that an axial force on the brake element in the direction of the input shaft leads to a rotation between an external thread and an internal thread and thus to an axial movement of the brake element in the direction of the friction element.

A preferred thread pairing provides that the brake element a

External thread and the housing comprises an internal thread. A reverse threaded arrangement in which the brake element has an internal thread and the housing an external thread, for example on a mandrel connected to the housing, is also possible.

Preferably, the axis of rotation of the brake element is aligned with the

Central axis of the applied thread on the brake element coincides with the axis of rotation of the input shaft, so that tilting moments between the brake element and the input shaft can be reduced.

In a preferred embodiment, the friction element is designed as a friction wheel and rotatably connected to the input shaft of the reduction gear. The friction torque influencing the speed of the transmission then arises before the first gear stage of the reduction gear. As a result, comparatively small changes in the frictional torque can significantly influence the speed of the output shaft of the reduction gear. The friction torque can be generated particularly effectively when the

Brake element comprises a braking surface which bears against a friction surface of the friction wheel and with rotating input shaft, the friction surface relative to the braking surface rotates and thereby the friction torque arises. Preferably, the braking surface of the brake element has a coefficient of friction that is greater than that

Coefficient of friction of the remaining brake element and / or the friction surface of the friction wheel has a coefficient of friction which is greater than the friction coefficient of the remaining friction wheel. Particularly high coefficients of friction can be achieved by coatings or surface treatments.

The housing preferably comprises a first housing section which at least partially accommodates the input shaft and a second housing section which at least partially accommodates the output shaft. The first housing portion and the second housing portion partially penetrate each other. In the area of the penetration, the inner cavities of the first housing section and the second housing section are connected to one another. As a result, gear elements of the first housing section arranged in the cavities can cooperate with gear elements of the second housing section. Under gear elements shafts, gears, worms, worm wheels, friction wheels or other known transmission elements are to be understood.

Particularly easy, the axial movement or preload of

Bremselementes done by means of a particular designed as a spring force accumulator, which moves the brake element against the friction wheel and biases against this. This results in an additional advantage when the spring via the brake element and the friction element always biases the input shaft in the direction of the electric motor, so that components within the electric motor, which are movable due to an axial clearance to each other, do not start against each other and thereby cause noise.

The reduction gear is preferably used such that the

Input shaft is driven by an electric motor. This can be the

Motor output shaft of the electric motor can be made in one piece with the input shaft of the reduction gear or connected thereto.

Preferably, the input shaft of the reduction gear is identical to the Motor output shaft and protrudes into the housing without being stored directly in this. However, instead of an electric motor, other known per se actuators or motors can drive the reduction gear. Reduction gear, comprising a screw which rotatably with the

Input shaft is connected and cooperates with a worm gear as a gear, can be particularly effective according to the invention perform, since these reduction gear have high reduction ratios. Preferably, a reduction gear according to the invention comprises a pinion which is rotatably connected to the output shaft and cooperates with the adjustment device of a motor vehicle seat. This provides a common interface to known adjustment devices. However, instead of the pinion, the output shaft can also have any other known coupling element for connecting shafts with other machine elements.

The use of the reduction gear is not limited to Sitzhöhenverstellvorrich- tions of motor vehicle seats, but can for example also be advantageous in conjunction with Sitzskissenneigungsverstellvorrichtungen or Lehnenneigungsverstellvorrichtungen or in applications outside the motor vehicle seat.

Figures and embodiments of the invention

In the following the invention is explained in more detail with reference to an advantageous embodiment shown in the figures. However, the invention is not limited to this embodiment. Show it:

Fig. 1: a perspective view of one with an electric motor

connected reduction gear according to the embodiment with a cut housing in the region of the motor shaft,

2 is a view corresponding to FIG. 1 in exploded view, 3 shows a detailed view of the cut-open housing in the region of the motor shaft, and FIG. 4 shows a view of the gear stage between worm and worm wheel without a housing.

The reduction gear 10 shown in Figure 1 comprises a housing 15 in which the individual transmission elements described below are mounted. An electric motor 12 is fixed to the housing 15, in the present case screwed. Alternatively, the housing of the electric motor 12 may be integrated into the housing 15. The electric motor 12 may also be an integral part of the reduction gear 10. The housing 15 comprises a first housing section 15a and a second housing section 15b. The first housing portion 15a comprises an elongated, hollow sleeve inside with a substantially circular cross section, which is closed at its end facing away from the electric motor 12 end. At a the electric motor 12 facing the end of the sleeve of the first housing portion 15 a, a flange for fixing the electric motor 12 to the housing 15 is provided.

The second housing portion 15b is designed substantially cylindrical. The cylinder longitudinal axis of the second housing portion 15b is aligned at right angles to the longitudinal axis of the first housing portion 15a. The first housing portion 15a and the second housing portion 15b penetrate each other partially. In the area of the penetration, the inner cavities of the first housing section 15a and of the second housing section 15b are connected to one another. As a result, gear elements of the first housing section 15a can interact with gear elements of the second housing section 15b in the manner described below. The electric motor 12 comprises a rotatable motor output shaft which in the present case at the same time forms an input shaft 20 of the reduction gear 10 projecting into the first housing section 15a of the housing 15. In a modification of the embodiment, the input shaft 20 is additionally rotatably mounted in the housing 15. In this case, the input shaft can be made in one piece with the motor output shaft of the electric motor 12 or rotatably connected thereto. In the embodiment and in the modifications of the embodiment thus rotates upon actuation of the electric motor 12, the input shaft 20 with the rotational speed of the electric motor 12th

A helical screw 22 is rotatably connected to the input shaft 20 and thus rotates upon actuation of the electric motor 12 at the speed thereof. A worm wheel 30 is in this case rotatably connected to an output shaft 40. The output shaft 40 is rotatably supported in the second housing portion 15b of the housing 15, preferably at an angle of 90 ° to the input shaft 20. The worm 22 engages the worm wheel 30, so that both in

Transmission connection with each other and with a rotational movement of the

Worm 22, the worm wheel 30 and thus the output shaft 40 is rotated.

A rotatably connected to the output shaft 40 pinion 42 is operatively connected to an adjusting device, not shown in the figures of a vehicle seat by the pinion 42 engages, for example, in a rack or in a gear of the adjusting device and thus the adjusting device can be actuated. In a modification of the embodiment, a further gear stage is arranged between the worm wheel 30 and the output shaft 40, For example, a wobble gear, as is known from DE 103 27 103 B4, the disclosure of which is expressly included in this regard.

In the region of the end remote from the electric motor 12 end of the input shaft 20, a friction element in the form of a friction wheel 25 is rotatably connected to the input shaft 20. The friction wheel 25 has a cylindrical basic geometry. Of the

Cylinder outer diameter is stepped once along the cylinder axis. The cylinder portion with the smaller outer diameter faces the electric motor 12; the cylinder portion with the larger outer diameter is remote from the electric motor 12 and has at its from the electric motor 12th

facing away from a friction surface 25a. Along its cylinder axis, the friction wheel 25 has an opening, preferably a circular bore 25b, whose diameter is slightly smaller than the outer diameter of the

Input shaft 20 is. The friction wheel 25 is on its bore 25 b on the

Slid input shaft 20 and pressed due to the mentioned diameter ratios. Alternatively, other known joining techniques for generating a rotationally fixed connection between the friction wheel 25 and

Input shaft 20 possible. The friction wheel is pushed onto the input shaft 20 far enough that the end of the input shaft 20 facing away from the electric motor 12 protrudes from the friction surface 25a, i. protrudes beyond the friction surface 25a.

A brake member 50 is guided along a direction aligned with the input shaft 20 in a manner described below axially movable in the first housing portion 15 a of the housing 15 and biased by means of a spring 60 designed as energy storage in the direction of the friction wheel 25. The brake element 50 has, on its end surface facing the friction surface 25a, a braking surface 52 which is in contact with the friction surface 25a due to the bias of the spring 60.

The brake element 50 has a cylindrical basic shape on which a

External thread 54 is applied. The external thread 54 is in an internal thread de 16 of the first housing portion 15 a screwed. The pitches of external threads 54 and internal threads 16 are designed to engage with each other outside of the self-locking so that a force in the axial direction (through spring 60) will twist the brake element 50 within internal thread 16 and thereby move axially within first housing section 15a can. Along its cylinder axis, which is aligned with the axis of the input shaft 20, the brake element 50 has an opening 50a, preferably a circular bore whose diameter is preferably slightly larger than the outer diameter of the input shaft 20. The protruding from the friction surface 25a end of the input shaft 20 is received by the opening 50a in the brake element.

The spring 60 is designed as a compression spring and also aligned with the

Input shaft 20. At a side facing away from the brake element 50 end of the spring 60, the spring 60 is supported on a surface of the first housing portion 15 a from. With a brake element 50 facing the end of the spring 60, the spring 60 is supported on a braking surface 52 facing away from the end face of the brake member 50 and pushes the braking surface 52 against the friction surface 25a of the friction wheel 25. The brake member 50 is thus in the axial direction between the spring 60 and the friction wheel 25 clamped and therefore can only move in the axial direction, when the spring 60 is tensioned under the circumstances described below. Thus, upon actuation of the electric motor 12 between the co-rotating with the input shaft 20 friction surface 25a and the non-co-rotating brake surface 52 to a relative movement, the one

Frictional torque generated. The friction torque is greater, the greater the force of the spring 60 and thus the contact pressure of the braking surface 52 on the friction surface 25a.

Due to the frictional torque between the friction surface 25 a of the with the

Input shaft 20 rotatably connected friction wheel 25 and the braking surface 52 of the brake element 50 experiences the brake element 50 upon actuation of the electric motor 12, a torque about the longitudinal axis, which tends to External thread 54 of the brake element 50 in the internal thread 16 of the first housing portion 15 a to rotate.

Upon rotation of the input shaft 20 in a first direction of rotation, the brake element 50 is pulled in the direction of the friction wheel 25, so that the

Contact pressure on the friction surface 25a continues to rise and thus the friction torque increases. Upon rotation of the input shaft 20 in an opposite, second rotational direction, the brake element 50 is minimally rotated due to the friction torque and moved away in the direction of the further exciting spring 60 of the friction surface 25a, so that the contact pressure on the friction surface 25a is reduced, which is the friction torque reduced accordingly.

Due to the direction of rotation dependency of the frictional torque, over the

Input shaft 20 acts on the electric motor 12, the Verstellgeschwindig- speeds can be unified in the upward and downward direction of an adjustment device. For example, in a seat height adjuster of a motor vehicle seat, the reduction gear is designed so that in a direction of adjustment of the seat up no or the smaller friction torque and in the adjustment direction down the larger friction torque is generated. The speed differences due to the weight of the occupant and seat are thus compensated.

The spring 60 also biases the input shaft 20 in the direction of the electric motor 12, so that all due to an existing axial play within the electric motor 12 slightly axially movable components are biased in one direction and thus noise due to the axial play, especially in a reversal of direction can be avoided.

In the modifications of the embodiment not shown in the figures, a friction element, in particular a friction wheel rotatably connected to the output shaft 40 or another arranged between the input shaft 20 and output shaft 40 and rotatable relative to the housing 15 gear member and acts with a mounted in the housing 15 brake element in appropriate Way together. The friction torque between the friction element and the brake element is dependent on the direction of rotation of the input shaft 20 as in the described embodiment. The features disclosed in the foregoing description, the claims and the drawings may be of importance both individually and in combination for the realization of the invention in its various forms.

LIST OF REFERENCE NUMBERS

Reduction gear

electric motor

casing

a first housing section

b second housing section

inner thread

input shaft

slug

Friction wheel, friction element

a friction surface

b bore

worm

output shaft

pinion

braking element

a opening

brake surface

external thread

feather

Claims

claims

1 . Reduction gear (10) with a housing (15), a relative to

Housing (15) rotatable input shaft (20) which is in gearbox connection with an output shaft (40) rotatably mounted in the housing (15), wherein a friction element (25) rotatably with a rotatable transmission element of the reduction gear (10) relative to the housing (15) is connected and with a braking element (50) cooperates, wherein the amount of a frictional torque between the friction element (25) and the brake element (50) on the direction of rotation of the input shaft (20) depends, characterized in that the braking element (50) is threaded (54) cooperating with a thread (16) of the housing (15) and the braking element (54) is rotatably and axially movably mounted in the housing (15).

2. reduction gear (10) according to claim 1, characterized in that the braking element (50) in an input shaft (20) at least partially receiving the first housing portion (15a) is mounted.

3. reduction gear (10) according to claim 1 or 2, characterized in that the braking element (54) has an external thread (54) and in an internal thread (16) of the housing (15, 15 a) is mounted.

4. reduction gear (10) according to one of claims 1 to 3, characterized

characterized in that an axis of rotation of the brake element (50) is aligned with the axis of rotation of the input shaft (20).

5. reduction gear (10) according to one of claims 1 to 4, characterized

in that the housing (15) comprises a second housing section (15b) which at least partially accommodates the output shaft (40).

6. reduction gear (10) according to claim 5, characterized in that the second housing portion (15b) comprises a cylindrical portion and the first housing portion (15a) and the second housing portion (15b) partially penetrate each other.

7. reduction gear (10) according to one of claims 1 to 6, characterized

characterized in that the friction element (25) is non-rotatably connected to the input shaft (20).

8. reduction gear (10) according to one of claims 1 to 7, characterized in that the friction element (25) is a friction wheel.

9. reduction gear (10) according to one of claims 1 to 8, characterized

characterized in that the braking element (50) comprises a braking surface (52) abutting a friction surface (25a) of the friction element (25), and in that the friction surface (25a) rotates relative to the braking surface (52) as the input shaft (20) rotates thereby the friction torque is created.

10. reduction gear (10) according to one of claims 1 to 9, characterized

characterized in that the braking element (50) by means of an energy accumulator (60) is biased against the friction element (25).

1 1. Reduction gear (10) according to one of claims 1 to 10, characterized in that the input shaft (20) by an electric motor (12) is drivable and with an engine output shaft of the electric motor (12) is identical.

12. reduction gear (10) according to one of claims 1 to 10, characterized in that the input shaft (20) by an electric motor (12) is drivable and with an engine output shaft of the electric motor (12) is connectable.

13. Reduction gear (10) according to one of claims 1 to 12, characterized in that a worm (22) rotatably connected to the input shaft (20) and the worm (22) cooperates with a worm wheel (30) as a gear stage.

14, reduction gear (10) according to claim 13, characterized in that the worm (22) cooperates with the worm wheel (30) as a first gear stage.

15. reduction gear (10) according to one of claims 1 to 14, characterized in that a pinion (42) rotatably connected to the output shaft (40) and the pinion (42) cooperates with an adjusting device of a motor vehicle seat.