AU1881102A

AU1881102A - Friction clutch for an adjusting drive

Info

Publication number: AU1881102A
Application number: AU18811/02A
Authority: AU
Inventors: Richard Guttenberger; Werner Seichter
Original assignee: Buehler Motor GmbH
Current assignee: Buehler Motor GmbH
Priority date: 2001-02-28
Filing date: 2002-02-28
Publication date: 2002-08-29
Also published as: JP2002266891A; DE10110034A1

Description

AUSTRAL IA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT e.

Applicant(s): BUHLER MOTOR GMBH Invention Title: FRICTION CLUTCH FOR AN ADJUSTING DRIVE The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 Friction clutch for an adjusting drive Description The invention concerns a friction clutch for an adjusting drive, with a clutch shaft, a clutch input gear, a clutch output gear, a first driving tenon, a spring shackle formed into an essentially open ring that abuts against a circumferential wall of a hollow space of the clutch output gear and has a second driving tenon.

This type of clutches serve the purpose of transmitting the force of the driving motor of an adjusting drive to an *"adjusting member via a reducing transmission. In case of .:eooi the driving motor breaking down, a manual adjustment of the adjusting member should be possible. To ensure a .i reliable driving when the adjustment is made by a motor, S' in the case of clutches of this type, when being actuated by a motor the frictional force is increased by the 20 expansion of the spring shackle without a negative influence on the manual adjustability.

In the case of a known friction clutch of this type the spring shackle is arranged directly on the clutch shaft, by virtue of which the frictional diameter and the torque transmitted by it is relatively small. A protrusion on the circumferential wall of the hollow space of the clutch output gear serves as a driving tenon. The plate thickness of the spring shackle determines essentially the magnitude by which the driving tenon protrudes from the circumferential wall. The service life is limited when using plastic material.

43358.doc 3 The invention provides a friction clutch of the generic type with a reliable drive when adjusted by a motor and a reliable slippage when adjusted manually with simultaneous long service life.

In a first aspect, the invention provides a friction clutch for an adjusting drive, including a clutch shaft, a clutch input gear, a clutch output gear, a first driving tenon, a spring shackle formed into an essentially open ring that abuts against a circumferential wall of a hollow space of the clutch output gear and has a second driving tenon, characterised in that the clutch input gear is integral with a hub and the first driving tenon, the diameter of the hub is considerably greater than the 0 15 diameter of the clutch shaft and the spring shackle is provided around the hub and is held in or on the first driving tenon in a rotationally fixed manner with the second driving tenon.

20 According to the invention the clutch input gear is integral with a hub and the first driving tenon, the diameter of the hub is considerably greater than the o diameter of the clutch shaft and the spring shackle is provided around the hub and is held in or on the first driving tenon in a rotationally fixed manner with the second driving tenon. By virtue of the hub it is possible to increase the friction radius of the friction surface between the cylindrical hollow space and the spring shackle.

Due to this the driving is more reliable and the torque at which the manual adjustment commences can be more accurately defined. In this case the shape and the 43358.doc 4 dimensions of the driving tenon are also easier adaptable to suit the required torque and the required service life.

The thickness of the driving tenon no longer depends from the thickness of the sheet metal of the spring shackle.

Preferably the friction clutch achieves a friction force that in the case of manual adjustment is essentially the same in both directions.

Further developments of the invention are represented in the sub-claims.

The greater the diameter of the hub, the more accurately °f o n ftf can the torques be defined, because the diameter of the •eeoc: 15 friction surface between the circumferential wall of the cylindrical hollow space in the clutch output drive and -the spring shackle increases to the same extent. A diameter, which is at least twice as large as the diameter of the shaft, is of advantage.

For an economical manufacture it is useful to make the clutch shaft integral with the clutch input gear.

The driving tenon can be constructed as a protruding web or as a rearward resilient groove. When a groove is used, at least one end of the spring shackle has to bent inwards to make a form-locking connection possible.

If at least one end of the spring shackle and/or the first driving tenon is so constructed that during the rotation of the clutch output gear an additional key effect occurs, a further increase of the frictional torque can be 43358.doc 5 achieved; an angle between 100 and 1200 formed between the end surfaces of the spring shackle is suitable for this.

A simple assembly is assured by the lead-in slope that is provided in the axial direction on the first driving tenon.

In a further embodiment the second driving tenon is constructed in the form of an end region of the spring shackle bent approximately towards the centreline of the hub and/or of the clutch shaft. By virtue of this a reliable drive is assured, in particular when the length *"of the second driving tenon and the thickness of the hub are matched to suit and full use is made of the thickness 15 of the hub.

To prevent a backlash, attempt is made to place that end of the spring shackle which is bent in the direction of the centreline of the hub and/or of the clutch shaft e 20 without any play in the rearward resilient groove.

To ensure a uniform slipping torque in both directions of rotation, it is suggested to bend one end region of the spring shackle inclined inward as a second driving tenon, the angle of the associated tangent on the open ring (spring shackle 5) being between 300 and 600. Due to this the ring will expand in both directions of rotation, in one direction in the form of a key effect and in the opposite direction by direct expansion. In the case of appropriately harmonised angle this expansion effect is the same for both directions of rotation.

43358.doc 6 A uniformity can also be achieved by that at least parts of both ends of the spring shackle are bent in the direction of the centreline of the hub and/or of the clutch shaft and they can be placed without any play in the rearward resilient groove. This will also be achieved when the ends of the spring shackle are slotted, whereby only a portion of the ends of the spring shackle is bent in the direction of the centreline of the hub and/or of the clutch shaft and a portion is frictionally connected on the inside circumference of the clutch output gear as a resilient element.

*"In a second aspect, the present invention provides a friction clutch for an adjusting drive, with a clutch shaft, a clutch input gear, a clutch output gear, a first driving tenon, a spring shackle formed into an essentially open ring that abuts against a circumferential wall of a hollow space of the clutch output gear and has a second driving tenon, characterised in that the second driving 20 tenon is provided in a region between the end regions of the spring shackle, whereby both driving tenons engage one another and independently from the actual diameter of the circumferential wall are joined with one another in a form-locking manner without any or almost without any play, while the force necessary to overcome the friction is completely or almost completely independent from the direction of rotation.

The second driving tenon is provided in a region between the ends of the spring shackle, whereby both driving tenons engage one another and independently from the actual diameter of the circumferential wall are joined with one another in a form-locking manner without any or 43358.doc 7 almost without any play, while the force necessary to overcome the friction is completely or almost completely independent from the direction of rotation.

The second driving tenon can be constructed as a bead, fold, protuberances produced by partial stamping, recess, cut-out, notch, protrusion or a combination of these.

The first driving tenon of a hub is preferably constructed as a recess in the hub.

In the following embodiments are explained in detail based on the drawing. They show in:

S*

S

Fig.l 1 an exploded illustration of a first embodiment of the friction clutch according to the invention, Fig.2 an exploded illustration of a first version of the first embodiments, Fig.3 a spring shackle of a first version of the first embodiment, Fig.4 a spring shackle of a second version of the first embodiment, a spring shackle of a third version of the first embodiment, Fig.6 a spring shackle of a second embodiment of the invention, 43358.doc 8 Fig.7 a spring shackle of a first version of the second embodiment, Fig.8 a spring shackle of a second version of the second embodiment, Fig.9a a spring shackle of a third version of the second embodiment, Fig.9b a sectioned illustration of Fig.9a along 'AA', 0096: and an adjusting drive with the friction clutch according to the invention.

.oo..i Fig.l shows an exploded illustration of a first embodiment of a friction clutch 1 according to the invention, with a clutch shaft 2, a clutch input gear 3, a first carrier 4a, a spring shackle 5 bent as an open ring, a clutch output 20 gear 6, a hub 7, a cylindrical hollow space 8 and a circumferential wall 9 acting as a friction surface. The clutch input gear 3, driven by a driving motor, in particular by a DC motor, possibly via a reducing transmission, is constructed integrally with the clutch shaft 2, the hub 7 and the driving tenon 4a. In the assembled state (not illustrated) the spring shackle surrounds the hub 7, and a second driving tenon 4b in the form of end surfaces 10, 11 and consequently end regions 13, 14 of the spring shackle 5 abut against the driving tenon 4a and they transmit the torque on to the circumferential wall 9 of the cylindrical hollow space 8 of the clutch output gear 6, said circumferential wall 9 interacting with the spring shackle 5 in a friction-locked 43358.doc 9 manner. When driven by a motor, the driving tenon spreads the end regions 13, 14 of the spring shackle 5 and consequently increases the frictional force. Due to the symmetrical design this effect is independent from the direction of rotation. When adjusted manually this spreading is not at all or at least not quite by the same extent, consequently an adjustment is possible without endangering the reducing transmission.

Fig.2 shows a first version of the first embodiment of the invention with a modified spring shackle 5 and hub 7. In this case as second driving tenon 4b an inwardly, :"approximately in the direction of the centre of the open ring, bent end region 14 of the spring shackle 5 is used, .ee.o) said second driving tenon engaging a rearward resilient groove 12 in the hub 7. The advantage of this embodiment is the assured driving of the steel shackle 5 by the driving tenon. However, the frictional forces can be different depending from the direction of rotation.

Fig.3 shows the spring shackle 5 of the first version of .*.the first embodiment with the two end regions 13, 14 and the second driving tenon 4b.

Fig.4 shows a second version of the first embodiment, wherein both end regions 13, 14 of the spring shackle are constructed as driving tenons 4b. The spring shackle is so symmetrically constructed that the same forces will act in both directions and the same torques can be transmitted.

Fig. 5 shows a particularly advantageous third version of the first embodiment of the invention, whereby only one 43358.doc 10 end region 14 of the spring shackle 5 is constructed as second driving tenon 4b. The peculiarity in this case is the direction in which the second driving tenon 4b is bent away from the open ring. The second driving tenon 4b is bent in such a manner that it is not inclined towards the centre nor as a tangent. The exact angle of the second driving tenon 4b is so chosen that the radial force remains essentially constant on the end region 14 for both directions of rotations. When rotating the spring shackle 5 clockwise, illustrated in Fig.5, always an expansion occurs. In contrast, when rotating it anti-clockwise, in the case of a too steep a second driving tenon 4b, a narrowing of the opening angle is the result. Only when the angle becomes flatter will a key-effect take place .:e.ei that expands the opening angle. To achieve this, the rearward resilient groove in the hub is formed with an incline to correspond to the driving tenon.

Fig.6 shows a second embodiment of the invention, with a 20 second driving tenon 4b that is situated in a region between the two end regions 13, 14 of the spring shackle In the case of this embodiment too, the same torque can be transmitted in both directions of rotation. Fig.7 shows a first version of this second embodiment. On this occasion the second driving tenon 4b has a wider construction than the second driving tenon 4b of Fig.6, as a result of which thicker sheet metals can be also used.

Fig.8 shows a second version of the second embodiment of the invention, wherein a region of the spring shackle produced, for example, by cutting in, is bent inwards as a second carrier 4b.

43358.doc 11 Figs.9a and 9b show a third version of the second embodiment of the invention, wherein a lateral notching from the spring shackle 5 between the two end regions 13, 14 serves as a second driving tenon 4b.

In the case of all embodiments and versions, with the exception of Figs.l, 9a and 9b, on the hub 7 at least one rearward resilient groove 12 is formed as a first driving tenon 4a, matching to suit the second driving tenon 4a. In the case of the embodiments according to Figs.l, 9a and 9b the first driving tenon 4a is formed as a protrusion.

Fig.l0 shows an example of an adjusting drive with the "4 friction clutch according to the invention. One deals here with a mirror drive 20, that can pivot a mirror glass about two pivot axes 23, 24 positioned perpendicularly to one another, each pivot axis having an electric motor 17, a first worm 18 (motor worm), a first worm gear (not visible), a second worm 19, a second worm gear 21, a third 20 worm 22, the clutch input gear 3, the friction clutch 1, the clutch output gear 6 and the clutch shaft 2, while all .*.electric motors and transmission elements are provided and I mounted in a drive housing 25. The drive of the mirror glass is carried out by means of cogged tension belts (not illustrated), which engage the relevant clutch output gear in a driving manner. The tension belts are connected under bias with a driven plate (not illustrated) in a pivoting manner, said driven plate carrying the mirror glass (not illustrated). The electric motors 17 and a portion of the transmission elements are snapped into the drive housing A transmission element is rotatably mounted between a first and a second part of the drive housing (not illustrated).

43358.doc

Claims

2. A friction clutch according to claim i, characterised in that the diameter of the hub is at least twice as large as the diameter of the shaft. 20 3. A friction clutch according to claim 1 or 2, characterised in that the clutch shaft is integral with the clutch input gear. o•
4. A friction clutch according to claim 1, 2 or 3, characterised in that the first driving tenon is constructed in the form of at least one protruding web or at least one recess, in particular as a rearward resilient groove.
5. A friction clutch according to at least one of the preceding claims, characterised in that at least one end region of the spring shackle and/or the first driving tenon are constructed in such a manner that during the
43358.doc 13 rotation of the clutch output gear an additional key effect occurs. 6. A friction clutch according to claim characterised in that the ends of the spring shackle are bent inwardly inclined in such a manner that an angle between 100 and 1200 formed between their end surfaces. 7. A friction clutch according to at least one of the preceding claims, characterised in that the first driving tenon has a lead-in slope at least in one axial direction. 8. A friction clutch according to claim 4, o characterised in that the second driving tenon is constructed in the form of an end region of the spring shackle bent approximately towards the centreline of the hub and/or of the clutch shaft. a.. 9. A friction clutch according to claim 8, 20 characterised in that that end of the spring shackle which is bent in the direction of the centreline of the hub and/or of the clutch shaft can be placed without any play in the rearward resilient groove. 10. A friction clutch according to claim 4, characterised in that one end region of the spring shackle is bent inclined inward as a second driving tenon, in such a manner that an angle of the associated tangent on the open ring (spring shackle 5) is between 300 and 11. A friction clutch according to claim 4 or 8, characterised in that at least parts of both ends of the spring shackle are bent in the direction of the centreline 43358.doc 14 of the hub and/or of the clutch shaft and they can be placed without any play in the rearward resilient groove. 12. A friction clutch according to claim 11, characterised in that the end regions of the spring shackle are slotted, whereby only a portion of the ends of the spring shackle is bent in the direction of the centreline of the hub and/or of the clutch shaft and a portion is frictionally connected on the inside circumference of the clutch output gear as a resilient element. ooeoe S13. A friction clutch according to claim 1, characterised in that a region between the end regions of 15 the spring shackle is bent in the direction of the centreline of the hub and/or of the clutch shaft and it can be placed in the rearward resilient groove. 14. A friction clutch for an adjusting drive, with a 20 clutch shaft, a clutch input gear, a clutch output gear, a first driving tenon, a spring shackle formed into an essentially open ring that abuts against a circumferential wall of a hollow space of the clutch output gear and has a second driving tenon, characterised in that the second driving tenon is provided in a region between the end regions of the spring shackle, whereby both driving tenons engage one another and independently from the actual diameter of the circumferential wall are joined with one another in a form-locking manner without any or almost without any play, while the force necessary to overcome the friction is completely or almost completely independent from the direction of rotation. 43358.doc 15 A friction clutch according to claim 14, characterised in that the second driving tenon is a bead. 16. A friction clutch according to claim 14, characterised in that the second driving tenon is a fold. 17. A friction clutch according to claim 14, characterised in that the second driving tenon is a protuberance produced by partial stamping. 18. A friction clutch according to claim 14, characterised in that the second driving tenon is at least *.one recess, cut-out, notch or protrusion or a combination of these. 19. A friction clutch according to at least one of the claims 14-18, characterised in that the first driving :tenon is a hub. S" 20 20. A friction clutch according to at least one of the claims 14-19, characterised in that the first driving tenon is a recess in the hub. S. 21. A friction clutch according to at least one of the preceding claims, characterised in that the hub is provided axially offset relative to the clutch input gear. 22. A friction clutch according to at least one of the preceding claims, characterised in that the friction clutch is provided in a mirror drive and acts between an electric motor and a mirror glass. 43358.doc 16 23. A friction clutch according to at least one of the preceding claims, characterised in that the end regions of the spring shackle are bent inward at least slightly. 24. A friction clutch substantially as herein described with reference to the accompanying drawings. Dated this 28th day of February 2002 BUHLER MOTOR GmbH 15 By their Patent Attorneys S. GRIFFITH HACK 0*0** 0* 06 0 43358.doc