METHOD FOR MOUNTING A SHAFT IN A BEARING TRACK OF AN INTERNAL COMBUSTION ENGINE

Abstract

The invention relates to a method for mounting a shaft (4), in which at least one sealing ring (2) is mounted on the shaft (4) such that said sealing ring engages into a circumferential groove (3).

It is essential to the invention here that a calibrating tool (1) having at least two radially displaceable partially circular clamping jaws (6) or a band clamp (7) is used, in order to press the sealing ring (2) into the respective groove (3) and to hold it in a force-fitting and form-fitting manner.

Claims

1. A method for mounting a shaft (4), in particular a camshaft (5), in a bearing track (18) of an internal combustion engine (19), in which at least one sealing ring (2) is mounted on the shaft (4) such that the at least one sealing ring (2) is widened and is pushed onto a region (8) of the shaft (4), in which at least one circumferential groove (3) is formed on the external diameter of the shaft (4), so that the sealing ring (2) is arranged in the groove (3), characterized by a positioning of a calibrating tool (1), having at least two radially displaceable partially circular clamping jaws (6), over the at least one sealing ring (2), a radial inward displacing of the clamping jaws (6) until their smallest internal diameter is greater than the external diameter of the shaft (4) in the region of the respective groove (3) and smaller than the external diameter of the at least one sealing ring (2) which is pushed onto the shaft (4) in the region of the groove (3), a pressing in of the at least one sealing ring (2) into the respective groove (3) and force-fitting and form-fitting holding of the sealing ring (2) in the groove (3), or a positioning of a calibrating tool (1), having a displaceable band clamp (7), over the at least one sealing ring (2), a tightening and thus an inward displacing of the band clamp (7) until its smallest internal diameter is greater than the external diameter of the shaft (4) in the region of the respective groove (3) and smaller than the external diameter of the at least one sealing ring (2) which is pushed onto the shaft (4) in the region of the groove (3), a pressing in of the at least one sealing ring (2) into the respective groove (3) and force-fitting and form-fitting holding of the sealing ring (2) in the groove (3).

2. The method according to claim 1, characterized in that the shaft (4) is introduced into a bearing (20) of a bearing track (18).

3. The method according to claim 2, characterized in that the calibrating tool (1) is withdrawn or removed from the shaft (4) during the introducing of the shaft (4) into the bearing track (18).

4. The method according to one of claim 2 or 3, characterized in that the shaft (4) is cooled before the introducing into the bearing (20) of the bearing track (18) and/or before the positioning of the calibrating tool (1).

5. The method according to one of the preceding claims, characterized in that the shaft (4) is cooled before the mounting of the at least one sealing ring (2), or that the shaft (4) is cooled jointly with the already pushed-on at least one sealing ring (2).

6. The method according to one of the preceding claims, characterized in that the at least one sealing ring (2) is pressed in with the calibrating tool (1) so far into the at least one groove (3) that the internal surface area of the sealing ring (2) in the region of its smallest internal diameter does not reach a base of the respective groove (3).

7. The method according to one of the preceding claims, characterized in that a sealing ring (2) is used which is formed at least partially from an elastically deformable polymer, in particular from a polytetrafluoroethylene (PTFE).

8. The method according to one of the preceding claims, characterized in that the calibrating tool (1) is released after a first radial compressing of the sealing ring (2), the calibrating tool (1) is rotated in circumferential direction with respect to the sealing ring (2), the calibrating tool (1) compresses the sealing ring (2) radially again.

9. The method according to one of the preceding claims, characterized in that for widening the sealing ring (2) for pushing onto the shaft (4) a widening tool (10) with two ring discs (11a, 11b) and with an elastomer ring disc (12) arranged therebetween is used, wherein an external diameter of the widening tool (10) is smaller than or equal to an internal diameter of the sealing ring (2), wherein the sealing ring (2) is pushed onto the elastomer ring disc (12) of the widening tool (10), the two ring discs (11a, 11b) of the widening tool (10) are moved towards one another, so that the elastomer ring disc (12) widens radially outwards and thereby also widens the sealing ring (2), the sealing ring (2) is pushed onto the region (8) of the shaft (4) with the groove (3) and further into the groove (3).

10. A shaft (4), in particular a camshaft (5), in which at least one sealing ring (2) is pressed into the respective groove (3) by a method according to one of the preceding claims and is held in a force-fitting and form-fitting manner.

11. A widening tool (10) for the method according to claim 9, with two ring discs (11a, 11b) and with an elastomer ring disc (12) arranged therebetween.

12. The widening tool according to claim 11, characterized in that the two ring discs (11a, 11b) are formed from plastic or from metal and are welded or bonded with the elastomer ring disc (12).

13. A calibrating tool (1) for a method according to claim 1, first alternative, characterized in that a clamping sleeve (13) is provided with at least two radially displaceable clamping jaws (6) extending in a finger-like manner in axial direction (14), the clamping jaws (6) at their free end have respectively a conically outwardly widening outer surface (15), a fixing ring (16), which is axially displaceable on the clamping sleeve (13), is provided with a conical internal surface area (17), the finger-like clamping jaws (6) move radially inwards, in so far as the fixing ring (16) is pushed on with its conical internal surface area (17) on the conically outwardly widening external surfaces (15) of the finger-like clamping jaws (6).

Description

[0020] There are shown, respectively schematically,

[0021] FIG. 1a a view onto a calibrating tool according to the invention for carrying out a method according to the invention with closed clamping jaws,

[0022] FIG. 1b an illustration as in FIG. 1a, however with opened clamping jaws and inserted sealing ring,

[0023] FIG. 1c an illustration as in FIG. 1b, however with closed clamping jaws,

[0024] FIG. 1d a view, partially in section, of a calibrating tool with inserted shaft and pressed-down sealing rings,

[0025] FIG. 2a an illustration as in FIG. 1a, however with a calibrating tool having three clamping jaws,

[0026] FIG. 2b an illustration as in FIG. 1b, however likewise with three clamping jaws,

[0027] FIG. 2c an illustration as in FIG. 1c, however likewise with three clamping jaws.

[0028] FIG. 3 a view onto a further possible embodiment of a calibrating tool according to the invention with clamping sleeve and fixing ring,

[0029] FIG. 4 a view, partially in section, through the calibrating tool according to FIG. 3 with closed clamping jaws and with a sealing ring pressed down into a groove of a shaft,

[0030] FIG. 5 a further possible embodiment of a calibrating tool according to the invention, with a band clamp,

[0031] FIG. 6 an axial view onto the calibrating tool illustrated according to FIG. 5, with opened band clamp,

[0032] FIG. 7 an illustration as in FIG. 6, however with tightened band clamp,

[0033] FIG. 8a a sectional illustration through a widening tool according to the invention,

[0034] FIG. 8b an illustration as in FIG. 8a, however with axially compressed widening tool,

[0035] FIG. 9a an illustration as in FIG. 8a, however with sealing ring arranged thereon,

[0036] FIG. 9b an illustration as in FIG. 8b, however with a sealing ring arranged thereon and widened.

[0037] According to FIGS. 1 to 7, a calibrating tool 1 according to the invention is shown, by means of which a sealing ring 2 can be calibrated or respectively compressed and thereby pressed into a groove 3 of a shaft 4, for example a camshaft 5 (cf. FIG. 1b to d, 2b and c, FIG. 4). The calibrating tool 1 has here at least two radially displaceable partially circular clamping jaws 6, (according to FIG. 1a to d, two clamping jaws 6, according to FIG. 2a to c, three clamping jaws 6 and according to FIG. 3 a total of eleven clamping jaws 6). In the case of the calibrating tool 1 according to FIGS. 5 to 7, this has a displaceable band clamp 7, by which through a contracting, a reducing of a diameter D of the sealing ring 2 can be achieved.

[0038] A method according to the invention for mounting a shaft 4 in a bearing track 18 of an internal combustion engine 19 is configured here as follows: Firstly, at least one sealing ring 2 is mounted on the shaft 4, in particular the camshaft 5, such that the at least one sealing ring 2 is widened and is pushed onto a region 8 (cf. FIG. 1d) of the shaft 4 in which a radially circumferential groove 3 is formed on the external diameter of the shaft 4, so that the sealing ring 2 is arranged in the groove 3, as is illustrated according to FIGS. 1d and 4.

[0039] Subsequently, in a first alternative of the method according to the invention, a positioning of a calibrating tool 1, having at least two radially displaceable and partially circular clamping jaws 6, over the at least one sealing ring 2 (cf. FIGS. 1 to 4) and subsequently a radially inward displacing of the clamping jaws 6 until their smallest common internal diameter is greater than the external diameter of the shaft 4 in the region of the respective groove 3 and smaller than the external diameter D of the at least one sealing ring 2 which is pushed onto the shaft 4 in the region of the groove 3. Through the radial inward displacing of the clamping jaws 6, the diameter of the sealing ring 2 is reduced from D.sub.1 to D.sub.2, whereby the sealing ring 2 is pressed into the groove 3. Through the calibrating tool 1 in addition a force-fitting and form-fitting holding of the sealing ring 2 in the groove takes place on a later introducing of the shaft 4 or respectively of the camshaft 5 in bearing 20 of the bearing track 18, for example of an internal combustion engine 19.

[0040] In a second alternative embodiment of the method according to the invention, the use of the calibrating tool 1, having the band clamp 7, according to FIGS. 5 to 7 takes place, in which firstly the calibrating tool 1, having the displaceable band clamp 7, is positioned over the at least one sealing ring 2 (cf. FIGS. 5 and 6). Subsequently, a tightening (cf. FIG. 7) and thus an inward displacing of the band clamp 7 takes place until its smallest internal diameter is greater than the external diameter of the shaft 4, for example of the camshaft 5, in the region of the respective groove 3 and is smaller than the external diameter of the at least one sealing ring 2 which is pushed on the shaft 4 in the region of the groove 3. This is illustrated according to FIG. 7. For calibrating or respectively compressing the sealing ring 2 and thus for a reducing of the external diameter D.sub.1 to D.sub.2, for example two retaining brackets 9a and 9b of the calibrating tool 1 are moved towards one another, so that their originally formed angle α.sub.1>0° (cf. FIG. 6) is reduced to α.sub.2=0° (cf. FIG. 7). Hereby, a pressing in of the at least one sealing ring 2 into the respectively associated groove 3 takes place, and a force- and form-fitting holding of the sealing ring 2 in the groove 3.

[0041] Also in the second alternative embodiment of the method according to the invention, the shaft 4, for example the camshaft 5 can be subsequently introduced or respectively pushed into bearings 20, not shown, of a bearing track 18, wherein the calibrating tool 1, during the introducing of the shaft 4 or respectively of the camshaft 5 into the bearing track 18 is withdrawn or removed from the shaft 4 or respectively the camshaft 5. By means of the calibrating tool 1 according to the invention, in particular an unintended projecting of an external diameter of the sealing ring 2 over the external diameter of the shaft 4 or respectively its region 8 with the groove 3 and thereby a damage to the sealing ring 2 on introducing into the bearing track 18 can be prevented here. For a facilitated mounting, the shaft 4 can be cooled before the introducing into the bearings 20 of the bearing track 18 and/or before the positioning of the calibrating tool 1 before the mounting of the at least one sealing ring 2, whereby the external diameter of the shaft 4 can be reduced and thereby a simplified arranging into the bearing track 18 can be achieved. The shaft 4 or respectively the camshaft 5 can be cooled before the mounting of the at least one sealing ring 2, wherein alternatively it is also conceivable that the shaft 4 or respectively the camshaft 5 is cooled jointly with the already pushed-on at least one sealing ring 2. In both cases, a reducing of the external diameter of the shaft 4, in particular its region 8 and thus also of the groove 3 is possible, in the second case also of the sealing ring 2, whereby the mounting in the bearing track 18 can be facilitated and a risk of damage to the sealing ring 2 can be reduced.

[0042] The at least one sealing ring 2 is pressed here with the calibrating tool 1 so far into the at least one groove 3 that an internal surface area of the sealing ring 2 in the region of its smallest internal diameter does not reach a base of the respective groove 3. Hereby, a damage to the respective sealing ring 2 on mounting can be prevented and, at the same time, the sealing effect which is able to be achieved through the elastic deformation of the sealing ring 2 can be improved, because the latter does not touch the base of the respective groove 3 both on mounting and also in operation of the respective internal combustion engine 19.

[0043] A shaft 4, in particular a camshaft 5, produced by the method according to the invention or respectively installed into a bearing track 18 of an internal combustion engine 19, and an internal combustion engine 19 with such a shaft 4, in particular such a camshaft 5, is of course also to be placed under protection.

[0044] The sealing ring 2 can be formed for example from an elastically deformable polymer, for example polytetrafluoroethylene (PTFE), which is of great advantage in particular for an application in internal combustion engines, because PTFE is resistant with respect to oil and, at the same time, has an extremely low friction coefficient. In addition, PTFE offers the great advantage that both the coefficient of static friction and also the coefficient of sliding friction are of equal amount, which facilitates in particular a rotation start of the shaft 4.

[0045] In order to be able to push the sealing ring 2 onto the region 8 of the shaft 4, it must firstly be widened, for which for example a widening tool 10 (cf. FIGS. 8 and 9) can be used. This widening tool 10 according to the invention has here two ring discs 11a and 11b and an elastomer ring disc 12 arranged therebetween, wherein an external diameter D.sub.3 of the widening tool 10 is smaller than, or maximally of equal size as, an internal diameter of the sealing ring 2. Hereby, it is possible to push the sealing ring 2 onto the widening tool 10 without difficulty, as is illustrated according to FIG. 9a. For widening the sealing ring 2, subsequently the two ring discs 11a and 11b of the widening tool 10 are moved towards one another (cf. FIGS. 8b and 9b), whereby the elastomer ring disc 12 arranged therebetween is compressed and the latter widens radially outwards, which leads to a widening of the sealing ring 2, which is arranged on the elastomer ring disc 12. The internal diameter D.sub.3 of the sealing ring 2 thus increases according to FIG. 9a on widening to the internal diameter D.sub.4 according to FIG. 9b. The widened internal diameter D.sub.4 of the sealing ring 2 corresponds here to the external diameter of the region 8 of the shaft 4, whereby a problem-free pushing of the sealing ring 2 onto the region 8 of the shaft 4 is made possible.

[0046] The two ring discs 11a, 11b can be formed for example from plastic or from metal, wherein the elastomer ring disc 12 which is arranged therebetween, is welded or bonded with the two ring discs 11a, 11b. Of course, for the moving of the two ring discs 11a, 11b towards one another and thus for a compressing of the elastomer ring disc 12 which is arranged therebetween, in addition a corresponding displacement mechanism must be provided, which can be realized for example by a sleeve and a stamp which is guided therein.

[0047] Observing further the calibrating tool 1 illustrated according to FIGS. 3 and 4, it can be seen that it has a clamping sleeve 13 with at least two radially displaceable clamping jaws 6 extending in a finger-like manner in axial direction 14, which clamping jaws have at their respective free end respectively a conically outwardly widening outer surface 15. A fixing ring 16, axially displaceable on the clamping sleeve 13, having a conical inner surface area 17, is also provided, wherein the finger-like clamping jaws 6 move radially inwards in so far as the fixing ring 16 is pushed with its conical inner surface area 17 onto the conically outwardly widening outer surfaces 15 of the clamping jaws 6, as is illustrated according to FIG. 4. Hereby, a calibrating or respectively compressing of the sealing ring 2 and thus a pressing thereof into the groove 3 can also be achieved.

[0048] In order to achieve as great a roundness as possible and, if applicable, to compensate effects, such as bulging, occurring at an impact of the calibrating tool 1, for example at the transition between the clamping jaws 6, the calibrating tool 1 can be moved apart again after a first calibrating step, and can subsequently be closed again, rotated about an angle. The calibrating tool 1 is thus released after a first radial compressing of the sealing ring 2, is subsequently rotated in circumferential direction to the sealing ring 2 and again subsequently closed again, whereby the sealing ring 2 is compressed radially once again.

[0049] With the method according to the invention, with the widening tool 10 according to the invention and with the calibrating tool 1 according to the invention, a comparatively simple calibrating or respectively compressing of the sealing ring 2, and requiring little installation space in axial direction 14, is possible and of great advantage, which would not be possible in particular in modern and confined internal combustion engines 19, in which the use of a longitudinally displaceable sleeve would not be possible. With the calibrating tool 1 according to the invention, of course also several sealing rings 2 can be calibrated, i.e. compressed, at the same time.