192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
1998-02-05
2001-02-20
Marmor, Charles A (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S098000
Reexamination Certificate
active
06189670
ABSTRACT:
The present invention relates to the field of clutch-release bearings, particularly for motor vehicles.
In general, clutch-release bearings comprise an operating member which can move in terms of translation on a guide tube under the action of a control member such as a clutch-release fork or the piston of a hydraulically controlled system, a thrust ball bearing intended to act on the clutch-release device of a clutch, such as a diaphragm and, between the thrust ball bearing and the operating element, a self-centering connection providing the axial connection between the thrust ball bearing and the operating element and allowing the thrust ball bearing to self-centre with respect to the diaphragm should the axis of the diaphragm and the axis of the thrust ball bearing not be exactly concurrent at the time of assembly.
The operating element may, on its free end, have a scraping seal. This scraping seal may serve to prevent dirt from getting in between the parts that can move relative to one another in translation. The problem is that a build up of assorted dirt between the guide tube and the operating element has detrimental effects on the correct operation of the mechanism because of the increase in the axial operating force, the deterioration of the contacting parts, and the risk of the mechanism seizing.
The scraping seal may also serve to hold a lubricant interposed between the operating element and the guide tube in the case of a mechanically controlled thrust bearing. In the case of a hydraulically controlled thrust bearing, the scraping seal also serves to prevent oil from leaking in the direction of the friction linings of the clutch disc, as such leaks could give rise to problems with the operating of the clutch, such as slipping or juddering.
Hydraulically controlled self-centring release bearings fitted with a scraping seal are described, for example, in document WO-A-96/24782. This type of thrust bearing requires several special components for acting as the scraping seal, for sealing the bearing, and for providing the self-centering connection. What is more, the bearing has a complicated shape and is relatively bulky in the radial direction.
Also known from the prior art is document FR-A-2,663,702 which relates to a clutch-release bearing equipped with an elastic self-centering connecting sleeve which has a front lip that forms a seal for the bearing. A release bearing of this kind has no scraping seal.
The object of the present invention is to overcome the drawbacks of the above devices.
Also, the subject of the present invention is a device for operating a clutch which provides an effective and inexpensive seal between the guide tube and the operating element.
The device for operating a clutch, according to the invention, is of the type comprising a thrust ball bearing, equipped with a non-rotating race and with a rotating race, capable of acting on a diaphragm of a clutch mechanism, an operating element comprising a tubular portion and a radial flange, which can move axially along a guide tube, and an elastic self-alignment member arranged radially between the thrust ball bearing and the tubular portion of the operating element. The elastic self-alignment member comprises an annular scraping lip which rubs against the guide tube to form a scraping seal. This thus provides a sealing element which is inexpensive and simple to mount, preventing the ingress of dirt between the operating element and the guide tube during the relative axial movement of these two parts under the action of an operating device, and also preventing any possible leaks of lubricant or of oil.
In one embodiment of the invention, the scraping lip is directed axially towards the clutch mechanism and radially towards the inside in order to provide good scraping.
Advantageously, the elastic self-alignment member and the scraping lip are of one piece. This then makes the device easier to mount while at the same time reducing the costs of manufacture.
In one embodiment of the invention, the elastic self-alignment member comprises a sleeve in contact with the bore of the non-rotating race of the thrust ball bearing. The bore of the sleeve has a number of ribs projecting radially towards the inside and extending axially along the width of the sleeve. The ribs are inclined and are in the form of strips, the free ends of which rest on the tubular portion of the operating member in order to achieve good self-centering.
Advantageously, the elastic self-alignment member comprises an additional annular lip which provides a seal between the non-rotating and the rotating races of the thrust ball bearing so that the said member fulfils three functions in an economic way.
In one embodiment of the invention, the free end of the tubular portion of the operating member comprises an annular bulge directed radially outwards to form an axial stop for the elastic self-alignment member. The thrust ball bearing is thus secured axially to the operating element. This securing is easy to achieve, the bearing fitted with the self-alignment member being mounted by sliding it in axially.
As a preference, the scraping lip is in contact with a bearing surface of the free end of the tubular portion of the operating member. The bearing surface may be oblique, for example at 45° forming a chamfer on the free end of the tubular portion and makes it possible to prevent any inverting of the scraping lip as the operating element moves relative to the guide tube. The bearing surface may advantageously be produced by means of the bulge on a surface thereof that faces the diaphragm but it is of course possible to provide the said bearing surface independently of the annular bulge, whether or not the latter exists.
The elastic self-alignment member may be secured to the non-rotating race by means of mating shapes, but securing may just as well be achieved by overmoulding or by bonding the said member into the said race.
The clutch-operating device may be mechanically, electro-mechanically or hydraulically controlled.
Thus an elastic self-alignment member capable simultaneously of fulfilling at least the functions of providing a self-centering connection and of a scraping seal is produced simply and economically, and this makes it possible to produce the number of parts and to simplify the bearing, the races of which are advantageously made of pressed sheet metal.
REFERENCES:
patent: 4077504 (1978-03-01), Ernst et al.
patent: 5113988 (1992-05-01), Caron
patent: 5205387 (1993-04-01), Checa
patent: 5743370 (1998-04-01), Thomire
patent: 2045380 (1980-10-01), None
patent: 2107818 (1983-05-01), None
Kromwel Jean Michel
Ponson Frederic
Marmor Charles A
Pang Roger
SKF France
Smith , Gambrell & Russell, LLP
LandOfFree
Device for operating a clutch with an elastic self-alignment... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for operating a clutch with an elastic self-alignment..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for operating a clutch with an elastic self-alignment... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2608647