ARRANGEMENT FOR CENTERING A BEARING UNIT OF A PULL-TYPE CLUTCH

Abstract: Upon fitting of a so-called pull-type clutch between engine (1) and gearbox (4) in vehicles, difficulties arise in achieving correct coupling between the declutching me­ chanism (5) and the declutching bearing during bringing together of engine and gearbox. A bearing unit (15) includ­ ing a declutching bearing is freely rotatable in a pre-assem­ bled condition and needs to be centred in a certain angular position for correct coupling to be obtained. In order to achieve this centring of the angular position of the bearing unit (15) it is proposed according to the invention that the bearing unit is connected to a housing (6), which is fixed relative to the engine, via an extensible element (25, 28) by means of which the said angular position may be fixed.

Description: The present invention relates to an arrangement according to the preamble of the main claim. So-called pull-type clutches on the drive units of motor vehicles have advantages with regard to function, service life and manufacturing costs when compared with so-called push-type clutches. The latter, however, have the advantage that they can be fitted simply when engine and gearbox are brought together, since the declutching mechanism only has to press on the declutching bearing. With a pull-type clutch, on the other hand, a coupling is required between the declutching bearing and the declutching mechanism. Since it is difficult, when engine and gearbox are brought together, to reach the declutching bearing and the declutching mechanism from the outside, it is desirable that the coupling as well as the uncoupling of these takes place substantially automatically. In the event that the declutching mechanism includes a declutching fork, its legs must then be moved, while engine and gearbox are brought together, into a position behind the lugs or the like which are generally found formed on the declutching bearing for interaction with the legs. A solution for achieving this is previously known from Swedish patent application 8501248-2. In this a wire spring arranged on the declutching bearing is used to interact with the legs of the declutching fork. With the rotatable declutching bearing and with it the wire spring in a pre-set angular position, the legs of the likewise pre-set declutching fork are then caused to move towards the wire spring, while engine and gearbox are brought together, so that the legs of the fork are moved to a position behind the lugs of the declutching bearing. The known solution referred to has disadvantages when applied to freely rotatable declutching bearings which, as a consequence of a non-symmetrical construction, can scarcely be pre-set in the angle of rotation position which is required in order that the desired interaction with the declutching fork can take place. The aim of the present invention is to achieve an arrangement as stated at the outset in which the disadvantages referred to are eliminated. To this end the invention is characterized by what is specified in the characterizing clause of the main claim. By virtue of the presence of the connecting element, which is referred to there and which fixes the angular position, between the declutching bearing housing and the housing which is fixed relative to the engine, the declutching bearing can be pre-set at the precise angular position in which to be correctly brought together with the legs of the declutching fork. The displaceability of the declutching bearing which is necessary for the declutching movement during normal operation of the vehicle can be achieved, notwithstanding the connecting element, by virtue of the stated extensibility. A further aim of the present invention has been to integrate, by means of the connecting element, a lubricant transfer to a sliding bearing situated in the declutching bearing. In one embodiment of the invention, therefore, the connecting element includes a flexible pipe which makes it possible to supply lubricant to the sliding bearing of the declutching bearing from outside. Other features characterizing the invention emerge from the accompanying patent claims and the following description of an embodiment illustrating the invention. In the description reference is made to the accompanying figures in which figure 1 shows a partial schematically reproduced view from above of an arrangement according to the invention before an imminent bringing together of engine and gearbox, figure 2 shows the said arrangement after bringing together, and figure 3 shows essentially a section along A-A in figure 1. It can be seen from figure 1 how a bearing unit 1 for a declutching bearing 2 is pre-assembled. The arrangement shown in the figures comprises a clutch 2 which is mounted on an engine 1 and which is brought, from a position before bringing together, by means of an axle 3 moving into a gearbox 4 and also by means of a declutching fork 5 mounted on the gearbox to an assembled operating position according to figures 2 and 3. The clutch 2 according to the arrangement according to the invention is of the conventional friction disc type which does not constitute part of the present invention and is consequently not described in greater detail here. It can be seen from figures 1 and 2 how the clutch 2 is surrounded by a flywheel housing 6 which is fixed to the engine 1. A diaphragm spring 8, which is non-rotatably connected to the flywheel 7 of the engine in a conventional manner which is not described here in greater detail, is attached centrally to the one ball race 10 of the declutching bearing 9. The other ball race 1 1 of the declutching bearing is firmly fixed in a housing 12 which has a radially inward-turned cylindrical casing surface 13. Together with the declutching bearing 9 the housing 12 is henceforward referred to as the bearing unit 15. The bearing unit 15 has an axial cylindrical hole running through it which is limited by the casing surface 13 and through which the inward moving axle 3 of the gearbox extends. Furthermore, the housing 12 of the bearing unit is provided with radially projecting lugs 16, one on each side of the housing. In between the housing is designed with a guide element 17 in the form of two legs 18 which are positioned radially and in a peripheral direction at a distance from one another. The said lugs 16 and the guide element are intended to interact with the declutching fork 5 which is fixed to the gearbox. The fork is pivotably mounted on a bearing bracket 19 which is fixed to the end wall 20 of the gearbox. The bearing bracket 19 is designed with a guide boss 21 which engages between the legs 18 of the guide element 17 in order to prevent turning of the bearing unit 15 during operation. In addition, the bearing unit 15 is provided with a radial boring (not shown). To this is fixed a connection 22 to a tube 23 for the supply of lubricant via the boring to the hole through the bearing unit 15. The cylindrical inner surface 13 of the hole in fact forms a sliding bearing together with a stay tube 24 which encloses the axle 3 and is fixed to the gearbox 4. The said sliding bearing makes possible axial displaceability between the bearing unit 15 and the stay tube 24 for carrying out the necessary declutching movement during normal operation of the vehicle. The supply of lubricant is intended to take place at predetermined service times for the vehicle. To the tube 23, therefore, a flexible hose 25 is attached which, at its radially outer end, is connected via a further tube 26 to a lubricator nipple 27 located outside the flywheel housing. Parallel with the hose 25 a tension spring 28 extends between the metal tubes 23, 26. Both the hose 25 and the spring 28 are designed as an extensible element which, during operation, makes possible the necessary declutching movement. In all positions, however, the tension spring 28 exerts a tensile force between the tubes 23, 26 and thus exerts a force for fixing the angular position on the bearing unit 15. The radially outer part of the declutching fork 5 passes through an opening 30 made for this purpose in a clutch housing 31 which is fixed to the gearbox. Outside the clutch housing 31 the outer end of the declutching fork interacts, in a way which is not shown here, with a piston rod issuing from a compressed air cylinder which is part of a manually actuable manoeuvring mechanism for the clutch. The radially inner part of the declutching fork consists of two legs 32, 33 which are intended to grip around the bearing unit 15. The ends of the legs 32, 33 are thus intended to interact with the lugs 16 of the bearing unit by assuming a position by the side of the lugs 16 which is turned away from the gearbox. It can be seen from figure 1 how the declutching fork 5, before bringing together of the gearbox and engine, has been pulled back to its maximum rearward position. Both the declutching fork 5 and the extensible element 25, 28 have an essentially horizontal extension which has the effect that the bearing unit 15, which is freely rotatable during bringing together, tends to turn itself, under the influence of gravity, out of a correct angular position for bringing together. According to the invention, however, the bearing unit 15 can be centred by attaching the outer section of tube 26 of the lubricant pipe 23, 25, 26 to the flywheel housing in a pre-determined position. This can be done either by mounting the outer section of tube 26 in a pre-determined hole in the flywheel housing 6 or by providing the outer section of tube 26 - as is the case in the figures - with a catch 35 which can grip around the edge of the flywheel housing 6 close by a pre-determined mark on the housing 6. The last-mentioned solution means that minor adjustments to the angular position of the bearing unit 15 can be made simply from outside in order to facilitate the passing of the declutching fork 5 between the legs 18 of the guide element 17. During bringing together the inward moving axle 3 of the gearbox 4 and its surrounding stay tube 24 are first passed into the hole in the bearing unit 15. The ends of the legs 32, 33 of the declutching fork 5 are then moved to a position seen from the engine side in front of the lugs 16 of the bearing unit 15 according to figure 1 at the same time as the guide boss 21 is moved in between the legs 18 of the guide element 17. When bringing together is completed by the housings 6, 31 having come into contact with one another, the ends of the legs of the declutching fork are brought into contact with the lugs 16 by manual actuation of the manoeuvring mechanism of the clutch. In the clutch housing a recess 36 is formed in which the tube 26 is accommodated when the housings 6, 31 make contact with one another. The above exemplary embodiment is not intended to have a limiting effect on the invention but it can be modified, within the scope of the following claims, in a number of embodiments. Thus, the extensible element 25, 28 between the bearing unit 15 and the flywheel housing 6 does not necessarily have to contain a lubricant pipe if, for example, the sliding bearing between the bearing unit 15 and the stay tube 24 is of a permanently lubricated type. In such a case it can be designed with just one extensible spring of the type shown in the figures or in the form of a plate spring. Nor does the extensibility in itself need to be achieved by means of a spring but can be achieved, for example, with a double pivoted connecting element between the bearing unit 15 and the flywheel housing 6. The flexibility of the element should then simply make possible the displaceability of the bearing unit 15 in an axial direction but not allow any turning of the bearing unit 15 around the inward moving axle 3.

Claims: Arrangement for centring of the angular position of a bearing unit (15) for a declutching bearing on a so-called pull-type clutch (2) between an engine (1) and a gearbox (4) in a vehicle, said bearing unit (15) being preassembled to and rotatable relative to a clutch (2) which is fixed to the engine (1) prior to a bringing together of the gearbox (4) and the engine (1), said clutch (2) being intended to be connected to and operated by a declutching mechanism (5) after the gearbox and the engine have been brought together, said declutching mechanism (5) being preassembled to the gearbox (4), characterized in that the bearing unit (15) is connected to a housing (6) fixed in relation to the engine (1) via an extensible element (25,28) by means of which the angular position of the bearing unit (15) is fixed prior to the bringing together of the gearbox (4) and the engine (1) to assume a fitted position adjusted for the connection with the declutching mechanism (5). Arrangement according to claim 1, characterized in that the extensible element includes a spring (28). Arrangement according to claim 2, characterized in that the extensible element includes a flexible pipe (25) connected in parallell to the spring (28) for the transfer of lubricant to the bearing unit (15). Arrangement according to claim 3, characterized in that the extensible element (25,28) is connected to the fixed housing (6) via a non-flexible tube (26) which is attached to the housing (6) and which is provided with a nipple (27) located radially outside the housing (6) and for transferring lubricant to a sliding bearing in the bearing unit (15). Arrangement according to claim 3, characterized in that the connection of the extensible element to the fixed housing (6) consists of a catch (35) which grips around one edge of the housing (6) for simple adjustability of the bearing unit (15) around a pre-determined angular position.

Inventors: LIONELL, HAKAN
Applicants: SAAB-SCANIA AKTIEBOLAG
Application year: 1988
Main classification: F16D23
IPC codes: F16D23