| Title of Invention | "RELEASE BEARING OF A DISCONNECTING CLUTCH" |
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| Abstract | The invention relates to a thrust washer (1) of a release bearing of a disconnecting clutch, the surface (10) of which that is remote from the clutch being in pressure contact with an annular flange of a peripheral bearing ring of the release bearing and the surface (3) of which that is near the clutch being in pressure contact with spring tongues (2) of a cup spring and additionally in positive engagement by means of holding arms (7) and webs (9) extending radially between the spring tongues (2). , An improvement of the structural strength and wear resistance as well as the securement and. noise development of the thrust washer (1) and the rapid self-centering of the release bearing is achieved by the thrust washer (1) having a reinforcement (5) and holding arms (7), preferably made of metal, and the plastic of the thrust washer (1) having a structure^ reinforcing and friction-reducing component and by microstructures being provided on the surface (10) that is remote from the clutch and on the surface of the preferably plastic-coated annular flange, for the rapid forming of a positive connection between these two surfaces. |
| Full Text | Title of the invention Release bearing of a disconnecting clutch Description Field of the invention The invention relates to a release bearing of a disconnecting clutch, in particular for motor vehicles with manual or automatic transmissions. Background of the invention DE 34 24 227 describes a plastic thrust washer' of a release bearing of a disconnecting clutch, the surface of which that is . remote from the clutch being in pressure contact with an annular flange of a peripheral bearing ring of the release bearing and the surface of which that is near the clutch being in pressure contact with spring tongues of a cup spring and additionally in positive engagement by means of holding arms and webs extending radially between the spring tongues. One of the disadvantages Of the thrust washer described is its low structural strength and high wear, which result in a correspondingly short useful life. Furthermore, the slippage between the surface of the thrust washer that is remote from the clutch and the annular flange of a peripheral bearing ring of the release bearing causes the development of a great amount of noise. Object of the invention The invention is based on the object of improving the generic thrust washer with respect to structural strength and wear resistance as well as securement, self-centering and development of noise. Summary of the invention The object is achieved by the features of independent patent claim 1. The metal reinforcement makes the thrust washer into a plastic-metal composite part of high structural strength. This avoids breaking up of the thrust washer towards the end of its useful life. The metal holding arms offer a considerably greater load-bearing capacity and useful life than the molded-on plastic holding arms from the prior art- The high structural strength and wear resistance of the thrust washer are also based on the structure-reinforcing and wear-reducing component in the plastic of tihe said washer, for example comprising carbon libers. The friction-reducing PT?E component minimizes the sliding friction between the spring tongues and their contact surface on the thrust washer and in this way facilitates the actuation of the clutch. A further advantage of the solution according to che invention is that the surface of the thrust washer that is remote from the clutch and the surface of the annular flange of the peripheral bearing ring, preferably coated with plastic, have microstructures, which lead to the rapid, positive connection between the two surfaces. As a result, the slippage between then and the accompanying noise are largely prevented and the self-centering of the release bearing is speeded up. The high wear resistance of the thrust washer according to the invention also depends on the wear-resistant, for example heat-treated, 17Cr34 sheet of the reinforcement. if the plastic overrnolding in a contact region of the spring tongues is worn, the useful life of the thrust washer is prolonged at least by the useful life of the reinforcement. The notches and apertures in the reinforcement increase its binding and structural strength. Additional stiffening is achieved by angled-away or doubled-over portions in the region of the bore and/or outside diameter and in the region of the webs. it is of advantage that the holding arms are evenly distributed over the circumference of the surface of the thrust washer that is near the clutch and can be snapped in between two neighbouring spring tongues and engage positively behind them. The way in which the holding arms are formed according to the invention has the effect that the application of axial pressure makes them snap in between two neighbouring spring tongues and engage positively behind them. In this way, a reliable axial connection is ensured between the thrust washer and the spring tongues. It is also advantageous that the holding arms are respectively arranged in pairs in the circumferential direction and that their holding projections that engage behind the spring tongues are facing away from one another. Since the holding arms and their holding projections are preferably produced according to the invention from heat-treated steel sheet or beryllium-bronze strip (CuZn37F37 or CuSn6Zn6F61)', there is no risk of them being damaged or broken off. In a further advantageous refinement of the invention, it is provided that radially extending webs, which sure of a width that is less than/equal to the distance between two neighbouring spring tongues and engage between them, are arranged between successive pairs of holding arms on the surface of the thrust washer that is near the clutch. In this way, additional prevention against twisting is created and forces occurring in the circumferential direction are kept away from the holding arms. A secure connection between the holding arms and the thrust washer is created by the holding arms being embedded in the plastic or being fastened to the latter, for example by ultrasonic welding, or fastened to the reinforcement, for example by spot welding, soldering, adhesive bonding or punch riveting, or formed in one.piece with the reinforcement. The large number of thermoplastics and their friction-and wear-reducing and strength-increasing additives make application-specific optimization of the material of the thrust washer possible. To improve the self-centering of the release bearing and to reduce the noise occurring during the self-centering as well as to support the prevention against twisting between the surface of the thrust washer that is remote from the clutch and the plastic-coated surface of the annular flange of the peripheral bearing ring, it is of advantage that ribs directed towards the center are provided on both surfaces as the microstructure and are formed as microribs that are perpendicular or inclined counter to the direction of rotation of the respective surface. As a result, the formation of a positive engagement between the contact surfaces is promoted, and- the development of noise occurring with the slippage is largely prevented. A further advantageous form of the invention is characterized in that a microstructure of the two surfaces is provided by molding on with an injection mold that has been blasted with a coarse abrasive or provided with micropyramids or microcones. The effectiveness of the micropyramids and microcones can likewise be increased by an inclination with respect to the direction of rotation of the respective surface. An advantageous development of the invention is that the microstructure is provided in the form of a corresponding crown toothing or a similarly effective shaping, which preferably can be produced on both surfaces by molding it on them or by forming it in them without removing material. The positive crown toothing 'has the effect that the release bearing is shifted forcibly, and consequently quickly, onto the axis of rotation of the clutch. This minimizes the slippage phase and the accompanying noise and the amount of wear. Brief description of the drawings Further features of the invention emerge from the following description and the drawings, in which exemplary embodiments of the invention are schematically represented and in which: Figure 1 shows a longitudinal section through a thrust washer according to the invention corresponding to the line A-A in Figure 2; Figures la,brc show a detail "Z" of Figure i in section in the various variants for improving Figure Id Figure le the positive engagement between the plastic part and the reinforcement; shows a partial section of the detail "Z" of Figure 1; shows a view of the thrust washer in the direction of the arrow "B"; Figure 2 shows a view of the thrust washer in the direction of the arrow "X" of Figure 1; Figure 3 shows a view of the thrust washer in the direction of the arrow "Y" of Figure 1; Figure 3a shows an enlarged partial view of the thrust washer in. the direction of the arrow "P" of Figure 3 with perpendicular microribs; Figure 3b shows an enlarged partial view as in Figure 3a, but with microribs inclined in a sawtooth form; Figure 4 shows a view of the thrust washer 1 in the direction of the arrow "Y" of Figure 1, but with crown toothing; Figure 4a shows a view of the thrust washer in direction "C" of Figure 4 on an enlarged scale; Figure 5 shows a view of the thrust washer 1 in the direction of the arrow "Y" of Figure 1, but with staggered toothing, and Figure 5a shows a view of the thrust washer in direction "D" of Figure 5. - 7 - Detailed description of the drawings Figure 1 shows a longitudinal section through a thrust washer 1 according to the invention corresponding to the line A-A in Figure 2. The latter represents a view of the thrust washer 1 in the direction of the arrow "X" of Figure 1, while Figure la shows a detail "Z" of Figure 1 in a broken-open form. The thrust washer 1 serves for transferring the releasing force of a release bearing to the spring tongues 2 of a cup spring of a disconnecting clutch. The disconnecting clutch with the cup spring and the release bearing are not represented. when the clutch is disengaged and engaged, sliding movements occur between the spring tongues 2 and a surface 3 of the thrust washer 1 that is near the clutch. AS a result, the latter surface becomes worn on the contact surface of the spring tongues 2. The contact surface is formed as a concavely curved peripheral channel 4, in which the ends of the spring tongues 22 engage with a curvature in the same sense. Underneath the peripheral channel 4 there is a reinforcement 5, which is also represented in Figure la. It has on the outer circumference of the thrust washer 1 an angled-away portion 6. The reinforcement 5 is formed as a circular ring, corresponding to the form of the thrust washer 1, and is overmolded with plastic apart from the angled-away portion 6. AS Figures 1, la and 2 reveal, provided on che surface 3 of the thrust washer 1 that is near the clutch are holding arms 7, which are evenly distributed over the circumference of the said surface and have holding projections 8. These holding arras can be snapped in between two neighbouring spring tongues 2 and engage positively behind them. The holding arms 7 are always arranged in pairs and the holding projections 8 that engage behind the spring tongues are always facing away from one another. In Figures Ib, Ic and Id, the reinforcement 5 is provided with doubled-over portions 14, apertures 13 and angled-away portions in the region of the bore and outside diameter, which increases the positive engagement between the plastic and the overmolded reinforcement. Separately from this/ or in addition, apertures and notches in the web region may improve the positive engagement. The holding arms 7 are produced according to the invention from spring steel or spring-elastic bronze strip, which are distinguished by elasticity and wear resistance. By applying axial pressure, they are snapped in between two neighbouring spring tongues 2 and engage positively behind the spring tongues 2. As Figure 1 reveals, the holding arms 7 are firmly connected to the reinforcement 5 by soldering, spot welding or punch riveting. They may, however, as Figure la shows, also be firmly connected to the thrust washer 1 by partial over-molding or by ultrasonic welding. In Figure Id, the holding arms 7 according to the invention are molded onto the reinforcement 5 in one piece. To prevent the thrust washer 1 from twisting with respect to the spring tongues 2, arranged on the surface 3 of the thrust washer 1 that is near the clutch are radially extending webs 9, which are connected to the said surface in one piece. Their width is less than/equal to the distance between two neighbouring spring tongues 2, between which the webs 9 engage. The latter absorb the lateral force of the - 9 .- spring tongues 2 and thereby relieve the holding arms 7 of forces acting in the circumferential direction. in Figure 3, a view of the surface 10 of the thrust washer 1 that is remote from the clutch is shown in the direction of the arrow "Y" of Figure 1. Belonging to the surface is an annular flange (not represented) of a peripheral bearing ring, which transfers the releasing force of the clutch to the surface 10. In order to minimise the slippage, along with noise and wear, occurring during clutch disengagement and to speed up the self-centering of the release bearing, friction-increasing microstructures are molded onto the corresponding surfaces and bring about a rapid, positive connection between the same. Examples of micros tructures that come into consideration are coarse-blasted surfaces, micropyramids or microcones, it also being possible for the latter to be formed in an inclined manner. In Figure 3, center-directed microribs 11, lla are arranged in the region of the detail "K". In Figures 3a, 3b, these are shown enlarged, seen from the direction of the arrow "B" of Figure 3 towards the thrust washer 1. In this case, the microribs 11 of Figure 3a stand perpendicularly on the surface 10 and the surface of the annular flange, while the microribs lla of Figure 3b are arranged in a sawtooth form, inclined counter to the direction of rotation of the surfaces, and as a result rapidly interlock with positive engagement. Particularly suitable for the synchronization and self-centering of the release bearing and the thrust washer 1 is a surface structure in the form of a crown toothing 17 or staggered toothing 18, which is arranged correspondingly on both surfaces. It may be produced - 10 - by forming it in the thrust surface of the peripheral bearing ring without removing material or by molding plastic onto the thrust washer or onto the peripheral bearing ring of the release bearing. - 11 - List of reference numerals 1 thrust washer 2 spring tongue 3 surface that is near the clutch 4 peripheral channel 5 reinforcement 6 angled-away portion 7 holding arm S holding projection 9 web 10 surface that is remote from the clutch 11 perpendicular rnicrorib lla microrib in sawtooth form 12 notch 13 apertures 14 doubled-over portion 15 angled-away portion 16 bump 17 crown toothing 18 staggered toothing Patent claims 1. A plastic thrust washer (1) of a release bearing of a disconnecting clutch, the surface (10) of which that is remote from the clutch being in pressure contact with an annular flange of a peripheral bearing ring of the release bearing and the surface (3) Of which that is near the clutch being in pressure contact with spring tongues (2) of a cup spring and additionally in positive engagement by means of holding arms (7) and webs (9) extending radially between the spring tongues (2) , characterized in that the thrust washer (1) has a reinforcement (5) and holding arms (7), preferably made of metal, and the plastic of the thrust wasber (1) has a structure-reinforcing and friction-reducing component and in that microstruetures arc provided on the surface (10) that is remote from the clutch and on the surface of the preferably plastic-coated annular flange, for the rapid forming of a positive connection between these two surfaces. 2. The thrust washer as claimed in claim 1, characterized in that the reinforcement (5) and holding arms (7) consist of thin, wear-resistant and preferably heat-treated !7Cr34 sheet, or beryllium bronze (CuSn37F37 or CuSn6Zn6FSl), which is molded onto or over with the plastic. 3. The thrust washer as claimed in claim 1, characterized in that the reinforcement (5) has notches (12) and apertures (13) in the region of the webs (9) and doubled-over portions (14) and angled-away portions (15) in the region of the bore and/or outside diameter. 4. The thrust washer as claimed in claim 1, characterized in that the holding arms (7) are distributed over the circumference of the surface (3) of the thrust washer (1) that is near the • clutch and can be snapped in between two neighbouring spring tongues (2) and engage positively behind them. 5. The thrust washer as claimed in claim ' 1, characterized in that the holding arms (7) a.re respectively arranged in pairs in the circumferential direction and their holding projections (8) that engage behind the spring tongues (2) are facing away from one another. 6. The thrust washer as claimed in claim 1, characterised in that radially extending webs (9) , which are of a width that is less than/egual to the distance between two neighbouring spring tongues (2) and engage between them, are arranged between successive pairs of holding arms (5) on the surface (10) of the thrust washer (1) that is near the clutch. 7. The thrust washer as claimed in claim 1, characterized in that the holding arms (7) are embedded in the plastic or fastened to the latter, for example by ultrasonic welding, or fastened to the reinforcement (5) , for example by spot welding, soldering, adhesive bonding or punch riveting, or formed in one piece with the reinforcement (5). 8. The thrust washer as claimed in claim 1, characterized in that, 'apart from the materials that are reinforced with a carbon fiber component PA 46 CF 30 PTFE 5 PPA-GF 30 PTFE 15 and PA46-GF 30 PTFE 5, the following materials and additives are suitable for the material of the thrust washer (1) and for the coating of the flange surface of the annular flange: thermoplastic material, preferably based on a high-temperature-resistant polyamide or other high-temperature-resistant thermoplastics, for example polyaryl ether ketones (PAEK), from the range of polyamides, preferably polyamide 46 (PA 46} or partly aromatic polyamides, preferably polyphthalamide (PPA) or polyhexamethylene-terephthalamide (PA 6T) or copolymers thereof with polyhexamethylene isophthaiamide (PA6T/6I) and/or polyhexamethylene adipinamide (PA6T/66, PA6T/6I/66) or polymethylpentamethylene terephthalamide (PA6T/MPMDT) with friction- and wear-reducing and strength-increasing additives, carbon fibers and/or aramid fibers in a proportion by weight of 1 to 40%, preferably carbon fibers with a proportion by weight of 20 to 30%, aramid fibers with a proportion by weight of 1 to 15% and solid lubricants such as molybdenum disulphide with a proportion by weight of 1 to 5%, together with or alternatively graphite in a proportion by weight of 1 to 10%, together with or alternatively polytetrafluoroethylene (PTFE) in a proportion by weight of 1 to 30%, preferably a PTFE component of 5 to 15% by weight, together with or alternatively polyphenylene sulphone (PPSo2, Ceramer] in a proportion by weight of , 1 to 30%, preferably 1 to 15% by weight. 9. The thrust washer as claimed in claim 1, characterized in that ribs directed towards the center are arranged on both surfaces as Che microstructure and are formed as microribs (11), (Ha) that are perpendicular or inclined counter to the direction of rotation of the respective surface. 10. The thrust washer as claimed in claim 1, characterized in that a microstructure of the two surfaces is provided by molding on with an injection mold that has been blasted with a coarse abrasive or provided with micropyramids or microcon.es, 11. The thrust washer as claimed in claim 1, characterized in that the microstructure is provided in the form of a corresponding crown toothing (17) or a similarly effective staggered toothing (18), which can be produced on both contact surfaces by molding it on them or by forming it in the contact surface of the peripheral bearing ring of the release bearing without removing material. |
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| Patent Number | 278147 | |||||||||
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| Indian Patent Application Number | 8595/DELNP/2007 | |||||||||
| PG Journal Number | 52/2016 | |||||||||
| Publication Date | 16-Dec-2016 | |||||||||
| Grant Date | 14-Dec-2016 | |||||||||
| Date of Filing | 07-Nov-2007 | |||||||||
| Name of Patentee | SCHAEFFLER KG | |||||||||
| Applicant Address | INDUSTRIESTRASSE 1-3, 91074 HERZOGENAURACH, GERMANY. | |||||||||
Inventors:
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| PCT International Classification Number | F16D 23/14 | |||||||||
| PCT International Application Number | PCT/EP2006/003662 | |||||||||
| PCT International Filing date | 2006-04-21 | |||||||||
PCT Conventions:
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