GB2168780A

GB2168780A - Divided fly-wheel

Info

Publication number: GB2168780A
Application number: GB08530945A
Authority: GB
Inventors: Manfred Caspar; Bernhard Schierling; Franz Hartig
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1984-12-22
Filing date: 1985-12-16
Publication date: 1986-06-25
Also published as: JPH0735844B2; GB8530945D0; DE3447181A1; FR2575255A1; JPS61215832A

Abstract

The divided fly-wheel comprises a first fly-wheel (7) for securing through first screws (5) to the crank-shaft (3) of an internal combustion engine and a second fly wheel (17) mounted rotatably through a bearing (15) on a bearing extension (9). The bearing extension (9), independently of the screws (5) holding the first fly-wheel (7) on the crank-shaft (3), is screwed through additional screws (11) either on the fly-wheel (7) or on the crank-shaft (3). A torsional vibration damper (19) couples the second fly-wheel (17) rotationally elastically with the first fly-wheel (7). The torsional vibration damper (19) forms a construction unit separate from the first fly-wheel (7) which can be subjected to an operational test with or without the bearing extension (9). The first fly-wheel (7) separate from the torsional vibration damper (19) renders possible a test run of the internal combustion engine before the fitting of the torsional vibration damper (19) and the second fly-wheel (17). <IMAGE>

Description

SPECIFICATION Divided fly-wheel The invention relates to a divided fly-wheel for securing on a crank-shaft of an internal combustion engine.

A divided fly-wheel for securing on a crank-shaft of an internal combustion engine is known from Fed. German Publication Specification No.

2,931,423, in which a first fly-wheel is screwed with the aid of screws to the crank-shaft. The first flywheel carries in one piece a bearing extension on which a second fly-wheel is rotatably mounted. A torsional vibration damper couples the two flywheels rotationally elastically with one another.

The torsional vibration damper comprises two damper parts coupled rotationally elastically with one another through springs, of which damper parts one is firmly connected with the second flywheel and the other is connected with the first flywheel through a friction device.

In the known divided fly-wheel the torsional vibration damper and the first fly-wheel form one construction unit. In practice this leads to problems in fitting. In the motor vehicle industry it is widely usual that while the vehicle manufacturer produces the internal combustion engine, parts supplied by supplier firms, such for example as a clutch for starting and gear-changing, are fitted on the internal combustion engine. In clutches usual hitherto the torsional vibration damper is a component of the clutch disc, so that the function of the torsional vibration damper can be tested before fitting. In the known divided fly-wheel this is not possible, since the torsional vibration damper is capable of functioning only after the fitting of both fly-wheels.

On the other hand however at least the first flywheel must be balanced together with the crankshaft, and test running of the internal combustion engine is possible only together with the first flywheel.

It is the problem of the invention to indicate a way in which a divided fly-wheel can be fitted more simply.

Within the scope of the invention the first flywheel is secured on the crank-shaft by means of first screw connections independently of the torsional vibration damper. The torsional vibration damper forms a pre-fitted unit and is connected with the first fly-wheel through second screw connections. In this way the first fly-wheel can be fitted on the internal combustion engine, so that a test run can be carried out. Moreover the torsional vibration damper can be subjected to a test for function without problem, so that the vehicle manufacturer can obtain complete units which are adjusted exactly especially as regards the spring ratings and friction equipment from the manufacturer of the torsional vibration damper. the torsional vibration damper does not have, as usual hitherto, to be assembled from its individual parts on the part of the vehicle manufacturer.

There is no danger of incorrect flitting, and even individual parts cannot be lost.

In a preferred development of the invention the bearing extension on which the second fly-wheel is mounted is made as a separate component from the first fly-wheel and is screwed together with the first fly-wheel to the crank-shaft through common screws. the securing screws are arranged on a common pitch circle. However one set of the screws of the pitch circle exclusively connects the first fly-wheel with the crank-shaft and serves for the securing of the first fly-wheel on the crankshaft independently of the bearing extension. In this case the heads of these screws are seated in apertures of the bearing extension.In this way with comparatively small space requirement it is possible to produce both a provisional connection between the crank-shaft and the first fly-wheel and a subsequent connection of the second fly-wheel mounted on the bearing extension with the crankshaft. the second fly-wheel is expediently likewise detachably mounted on the bearing extension, so that the manufacturer of the internal combustion engine can pre-fit the bearing extension perhaps independently of the second fly-wheel.

Examples of embodiment of the invention are to be explained in greater detail below with reference to drawings, wherein: Figures 1 and 2 show axial longitudinal sections through the upper and lower halves of a first form of embodiment of a divided fly-wheel for an internal combustion engine; Figure 3 shows a representation of principle with the arrangement of screws for the securing of a first fly-wheel on the crank-shaft; Figure 4 shows a partial axial longitudinal section through a first variant of the divided fly-wheel according to Figure 1; Figure 5 shows a partial axial longitudinal section through a second variant of the fly-wheel according to Figures 1 and 2; Figures 6 to 10 show partial axial longitudinal sections through details of further variants of the divided fly-wheel.Figure 8 representing a sectional view seen along a line VIII-VIII in Figure 5; Figures 11 and 12 show the upper and lower halves of an axial longitudinal section through a second form of embodiment of a divided flywheel; Figure 13 shows a partial axial longitudinal section through a third form of embodiment of a divided fly-wheel, and Figure 14 shows a partial axial longitudinal section through a fourth form of embodiment of a divided fly-wheel.

Figures 1 and 2 show a motor vehicle crank-shaft 3 rotating about a rotation axis 1, to which shaft a first fly-wheel 7 is secured by means of necked screws 5. A bearing extension 9 separate from the first fly-wheel 7 and arranged on the side of the fly-wheel 7 remote from the crank-shaft 3 is likewise secured on the crank-shaft 3 with the aid of securing screws, especially necked screws 11. As shown by Figure 3, the screws 11 are arranged together with the screws 5 at equal angular intervals on a common pitch circle 13 and serve at the same time for the securing of the fly-wheel 7. A second fly-wheel 17 is rotatably mounted on the bearing extension 9 in a manner explained in greater detail hereinafter by means of a bearing 15, for example a ball bearing or even a plain bearing. A torsional vibration damper 19 couples the fly-wheels 7, 17 rotationally elastically with one another.The second fly-wheel 17 in the usual manner forms a counter-pressure face 20 for a clutch disc 21 of a motor vehicle friction clutch, the clutch housing of which is indicated at 23.

The second fly-wheel 17 is fixed rotatably but axially fixedly on the bearing extension 9 through the torsional vibration damper 19 and the bearing 15.

By means of the screws 5 of the flywheel 7 can be fitted on the crank-shaft 3 independently of the torsional vibration damper 19 and the second flywheel 17, so that a test running of the internal combustion engine can be carried out even before the torsional vibration damper 19 and the second fly-wheel 17 are fitted. A few screws 5, for example two or three, suffice for this provisional securing of the fly-wheel 7. The final securing of the fly-wheel 7 takes place together with the bearing extension 9 by means of the screws 11, which are longer than the screws 5. The heads of the screws 5 here engage in openings 25 of the bearing extension 9 which are covered by a washer 27 for the support of the screws 11.A dowel pin 29 arranged in the region of the pitch circle 13, preferably on the pitch circle 13, ensures correct orientation of the bearing extension 9 in relation to the first fly-wheel 7.

The torsional vibration damper 19 comprises two annular side discs 31,33 arranged with axial spacing from one another which are firmly connected with one another in the region of their external circumference by a plurality of distance rivets 35 distributed in the circumferential direction. Radially within the distance rivets 35 the side discs 31, 33 are secured to one another by further distance rivets 37. A hub disc 39 is arranged rotatably through a limited angle of rotation in relation to the side discs 31,33 axially between these discs. The hub disc 39 has on its internal circumference a hub 41 fixed axially on the bearing 15. Helical compression springs 49 which couple the side parts 31, 33 rotationally elastically with the hub disc are seated in windows 43 of the hub disc 39 for one part and windows 45, 47 aligned axially thereto of the side discs 31, 33 for the other part.Figure 1 shows only one of the springs 49, although several springs are provided in distribution in the circumferential direction. The side disc 33 adjacent to the first flywheel 7 is screwed to the first fly-wheel 7 from the side of the second fly-wheel 17 with the aid of screws 51 in the region of the external circumference of the side disc 33. The second fly-wheel 17 is screwed with the aid of screws 53 to the external circumference of the hub disc 39 from the side of the second fly-wheel 17 remote from the first flywheel 7. the screws 53 are arranged on a pitch circle the radius of which is larger than that of the pitch circle of the screws 51. The screws 51 are axially accessible to screwdrivers through openings 55 of the second fly-wheel 17, apertures 57 of the side disc 31 and openings 59 of the hub disc 39.

Both the screws 51 and the screws 53 are arranged on the side of the spring 43 radially remote from the axis 1 of rotation.

While in the upper half of Figure 1 the side disc 33 encloses a distance sleeve 61 axially fixing the bearing 15, in Figure 2 a variant is illustrated in which the side disc 33 is prolonged radially inwards between the bearing extension 9 and the first fly-wheel 7. The screws 11 are used at the same time for the securing of the internal circumference of the side disc 33. Furthermore in Figure 2 the screws 11 represented in Figure 1 as necked screws are formed as tight-fit screws, so that the dowel pin 29 as represented in Figure 1 may if desired be omitted.

The torsional vibration damper 19 comprises two friction devices 63, 65 which can be of conventional formation and are arranged axially between the side discs 31, 33. The friction devices 63, 65 are components of the construction unit which forms the torsional vibration damper.

For the fitting of the divided fly-wheel according to Figures 1 and 2 firstly the first fly-wheel 7 is provisionally secured on the crank-shaft 3 by means of the screws 5 for the test run of the internal combustion engine. Then the torsional vibration damper is fitted by means of screws 11 and 51. After the fitting of the torsional vibration damper the second fly-wheel 17 is screwed on by means of the screw 53, represented in Figure 1 in a partial section offset in the circumferential direction. Thereupon the fitting of the clutch disc 21 and the clutch cover 23 on which for example the presser plate and the spring devices of the clutch are held takes place as usual.

Variants and other forms of embodiment of the divided fly-wheel are to be explained below. Parts of like effect are provided with the same reference numerals and with an additional letter for distinction. For more detailed explanation reference is made to the description of Figures 1 to 3.

Figure 4 shows a divided fly-wheel which differs from the fly-wheel according to Figures 1 and 2 essentially only in that the screws 51a screwed in from the side of the crank-shaft 3a for the securing of the side disc 33a of the torsional vibration damper 19a are secured on the first fly-wheel. The screws 51a are accessible to screwdrivers either axially or from radially outwards through apertures 67 of the first fly-wheel 7. The openings or apertures 55, 57 and 59 can be omitted in this case.

The divided fly-wheel according to Figure 5 differs from the fly-wheel according to Figure 1 essentially only in the nature of the screw fastening with which the side disc 33b of the torsional vibration damper 19b is secured in the region of its external circumference to the first fly-wheel 7b and in the nature of the screw fastening with which the second fly-wheel 17b is held on the hub disc 39b.

In place of screws screwed into the side disc, a stay bolt 51b is seated in an opening 69 of the side disc 33b. The stay bolt has a head 71 welded to the side disc 33b ion the side of the side disc 33b remote from the fly-wheel 7b. A nut 73 for securing to the fly-wheel 7b is screwed on to the stay bolt 51b. The nut 73 is radially accessible through an aperture 75. In place of the screws 53 screwed into the hub disc 39b, in the case of the fly-wheel according to Figure 5 stay bolts 53b are provided which carry an annular collar 77 on the side adjacent to the fly-wheel 17b and are riveted into a flat head 79 on the side of the hub disc 39b remote from the annular collar 77. The annular collar 77 serves at the same time as spacer between the hub disc 39b and the second fly-wheel 17b.The second fly-wheel 17b is screwed to the hub disc 39b with the aid of nuts 81 which are accessible from the side of the second fly-wheel 17b remote from the first fly-wheel 7b.

Figure 6 shows a variant of the divided fly-wheel according to Figure 5 in which the hub disc 39c of the torsional vibration damper again carried stay bolts 53c for the securing of the second fly-wheel 17c. The stay bolt 53c has a head 85 guided fast in rotation by means of a shape-engaging connection in a depression 83 on the side of the hub disc 39c remote from the fly-wheel 17c. Between the hub disc 39c and the fly-wheel 17c a distance sleeve 87 is arranged on the stay bolt 53c. A nut 89 tightens the fly-wheel 17c through the distance sleeve 87 against the hub disc 39c. The nuts 89 are again freely accessible from the drive-output side of the clutch disc.

Figure 7 shows a variant in which collared nuts 91 are pressed into the hub disc 39d, into which nuts headed screws 53d are screwed from the drive-output side of the divided fly-wheel for the securing of the second fly-wheel 17d. The headed screws 53d serve at the same time for the securing of the clutch cover 23d.

Figure 8 shows a variant of the divided fly-wheel according to Figure 5 in which the side disc 33e is screwed to the fly-wheel 7e by means of screw connections each consisting of a stay bolt 51e and a nut 73e. The screw connection differs from the form of embodiment according to Figure 5 merely in the nature of the fastening of the head 71e of the stay bolt 51e. the head has securing faces 91 departing from the circular form and is held fast in rotation by material accumulations 93 which are swaged out of the side disc 33e. In the axial direction the head 71 is secured by a peened-over portion 95 on a material accumulation 97.

Figure 9 shows a further variant for the securing of the side disc 33f on the first fly-wheel 7f by means of a stay bolt 51f. The stay bolt 51f has a annular collar 99 on the side facing the fly-wheel 7f and is riveted into a head 101 on the side remote from the fly-wheel 7f. The fly-wheel 7f is secured on the side disc 33f by nuts 73f screwed on to the stay bolts.

In the variant according to Figure 10 into the side disc 339 to be secured to the first fly-wheel 79 there is inserted a collared nut 103 into which a screw 51g is screwed from the side of the flywheel 7g remote from the side disc 33g. The screw 51g is accessible from radially outwards through an aperture 679.

In the configuration of the divided fly-wheel as explained above the first fly-wheel, adjacent to the crank-shaft, is connected with a side disc of the torsional vibration damper, while the hub disc of the torsional vibration damper is secured on the second fly-wheel and guided rotatably but axially fixedly through the hub disc on the bearing. In the examples of embodiment according to Figures 11 to 14, explained below, it is ensured that the torsional vibration damper is independent of the bearing extension provided for the bearing mounting of the second fly-wheel, and does not have to be fitted together with the bearing extension. The bearing extension and the bearing of the second fly-wheel therefore do not have absolutely to pertain to the extent of the supply of the torsional vibration damper.In the forms of embodiment explained below again however parts of like effect are designated by reference numerals of Figure 1.

Figures 11 and 12 show a first fly-wheel 7h which is secured both through necked-down screws 5h and also through a bearing extension 9h by means of necked-down screws 11h on the crank-shaft 3h. A hub 41h is mounted rotatably on the bearing extension 9h through a bearing 15h, to which hub, in contrast to the forms of embodiment explained above, the two side discs 31h and 33h of the torsional vibration damper 19h are secured through the rivets 37h. The side discs 31h and 33h radially inwardly overlap the bearing 15h, for the axial fixing of the torsional vibration damper 19h.

Axially between the side discs 31h and 33h there is rotatably arranged an intermediate disc 39h which, in departure from the hub disc 39 in Figures 1 and 2, is rotatable in relation to the hub 41h. The intermediate disc 39h is moreover screwed with screws 41 h to the first fly-wheel 7h. The screws are accessible to screwdrivers from the drive-output side through openings 55h and 57h of the second flywheel 17h and the side disc 31h respectively. The second fly-wheel 17h is screwed, as represented in Figure 12, by means of screws 53h to collared nuts 105 which are inserted into the side disc 31h. If desired the securing of the clutch cover 23h can take place together with the second fly-wheel 17h, as represented in Figure 12 by prolonged screws 107.

In distinction from Figures 1 and 2 the bearing 15h is fixed axially on the side axially remote from the first fly-wheel 7h by the annular disc 27h protruding radially outwards beyond the bearing extension 9h. Since the annular disc 27h is secured by means of the screws 11h which hold the bearing extension 9h, the bearing extension 9h can be supplied separately from the torsional vibration damper 19h. The dowel pin 29h reaches from the bearing extension 9h through the first fly-wheel 7h into the crank-shaft 3h. The torsional vibration damper 19h again comprises two friction devices 63h and 65h, of which the one is arranged axially between the bearing extension 9h and the side disc 33h adjacent to the first fly-wheel 7h and the other axially between the two side discs 31h and 33h.

In the case of the fly-wheel according to Figures 11 and 12 the friction unit 62h is clamped in between shoulders of the bearing extension 9h and the side disc 33h which point axially towards one another. This has certain disadvantages in fitting if the bearing extension 9h does not pertain to the scope of what is supplied with the torsional vibration damper 19h. However it is ensured in every case by the annular disc 27h that the bearing extension 9h can also be supplied separately from the torsional vibration damper 19h, if desired. If the bearing extension 9h pertains to what is supplied with the torsional vibration damper 19h, the annular disc 27h can be scured on the bearing extension by additional securing screws (not shown).

However the final securing takes place by means of the screws 11 h.

In the fly-wheel according to Figures 11 and 12 the bearing 15h pertains to what is supplied with the torsional vibration damper 19h, since it is riveted in between the side discs 31h and 33h. Figure 13 shows a variant of a divided fly-wheel in which the torsional vibration damper 19i for the one part and the bearing extension 9i including the bearing 15i and possibly the hub 41i for the other part form separately supplied units. The bearing 15i is fixed axially on the bearing extension 9i similarly to the fly-wheel according to Figures 11 and 12 by the annular disc 27i, which is prolonged radially outwards beyond the bearing extension 9i. The annular disc 27i is held on the bearing extension 9i by additional securing screws, independently of the securing screws 11i.The side disc 33i, which is firmly connected with the side disc 31i by means of distance rivets 35i and 37i, is screwed from the drive-output side to the first fly-wheel 7i by means of screws 51 i, on the side of the springs 49i remote from the axis 1i of rotation. The screws are accessible to screwdrivers through openings 55i of the second fly-wheel 17i. In contrast to the forms of embodiment as explained above, the second flywheel 17i is not screwed on the side of the hub disc 39i radially remote from the rotation axis li, but is attached in the region of its internal circumference by means of screws 111 accessible from the drive-output side. The hub disc 39i is connected at its internal circumference by means of a toothing 113 fast in rotation with the hub 41i.In this way the torsional vibration damper 19i can be pushed axially on to the hub 41i and is fixed axially by means of the screws 51i. A friction device 65i arranged axially between the two side discs 31i and 33i fixes the hub disc 39i in relation to the side discs 31i, 33i. Axially between the faces of the hub 41 i and of the second fly-wheel 17i which are pressed against one another by means of the screws 111 an annular disc 113 is inserted which grasps radially inwards over the bearing 15i and fixes the hub 41i axially on the bearing 15i. In addition an annular thermal insulating washer 115 is inserted between the second fly-wheel 17i and the annular disc 113 which thermally insulates the bearing 15i from the second fly-wheel 17i. so that bearing damage due to over-heating is avoided.

The clutch cover 23i is secured to the second flywheel 17i separately with screws 117.

Figure 14 shows a variant of a divided fly-wheel in which similarly to the fly-wheel according to Figure 13 the torsional vibration damper 19k forms a construction unit which can be prepared as a delivered unit separate from the bearing extension 9k and the bearing 15k. The fly-wheel differs from the fly-wheel according to Figure 13 essentially in that both the side discs 31k, which are connected with one another by distance rivers (not shown), and the intermediate disc 39k are mounted rotatably on the hub 41k. The intermediate disc 39k is screwed in the region of its external circmference to the first fly-wheel 7k from the drive output side by means of screws 51k. The screws 51k are accessible axially to screwdrivers through apertures 55k and 57k of the second fly-wheel 17k and of the side disc 31k adjacent to the second fly-wheel 17k.For the rotation-fast connection of the side discs with the second fly-wheel 17k the side disc 31k carries collared nuts 119 into which screws (not further illustrated) are screwed from the drive-output side of the second fly-wheel 17k. The second fly-wheel is additionally screwed in the region of its internal circumference by means of screws 121 to the hub 41k, and similarly to the parts 113,115 in Figure 13 an annular disc 123 axially fixing the torsional vibration damper 19k and thermal insulation washer 125 are inserted between the hub 41k and the second fly-wheel 17k. In this way the torsional vibration damper can be supplied in a delivery unit with or even without the second fly-wheel 17k or also with or without the bearing 15k and/or the bearing extension 9k.Similarly to the forms of embodiment as explained above, it comprises a friction device 65k arranged axially between the two side discs 31k and 33k and a friction device 63k clamped in axially between the hub 41k and the bearing extension 9k. The annular disc 123 also protrudes radially inwards beyond the hub 41k and fixes the hub 41k to the bearing 15k. The bearing 15k is fixed axially according to Figure 13 by the annular disc 27k secured on the bearing extension 9k. The annular disc 27k can again be secured on the bearing extension 9k by additional securing screws 127, independently of the screws 11k.

The examples of embodiment of a divided flywheel as explained above render possible the manufacture and testing of the damper devices independently of the first fly-wheel for securing to the crank-shaft. Thus the first fly-wheel can be secured on the crank -shaft independently of the vibration damper, so that test running of the internal combustion engine is possible before the fitting of the torsional vibration damper. The second flywheel can be fitted independently. Thus repair of individual parts of the divided fly-wheel is easily possible. The extent of supply of the components of the divided fly-wheel is variable.

Claims

1. Divided fly-wheel for securing on a crankshaft (3) of an internal combustion engine, comprising a. a first fiy-wheel (7) screwable to the crankshaft (3) through first screw connections (5), b. a bearing extension (9) stationary in relation to the first fly-wheel (7), c. a second fly-wheel (17) mounted on the bearing extension (9) rotatably in relation to the first fly-wheel (7), d. a torsional vibration damper (19) having two damper parts (31, 33, 39) rotatable in relation to one another through a limited angle of rotation and connected rotationally elastically with one another through a plurality of springs (49), of which one of the two damper parts comprises two side discs (31,33) arranged with axial spacing from one another and connected fast in rotation with one another and with one of the two fly-wheels (7,17) and the other damper part comprises an intermediate disc (39) arranged between the side discs (31, 33) and connected fast in rotation with the other of the two fly-wheels (7, 17), characterised in that the torsional vibration damper (19) forms a preassembled unit and is fittable on the first fly-wheel (7) through second screw connections (11) independently of the first screw connections (5).

2. Fly-wheel according to Claim 1, characterised in that the damper part of the torsional vibration damper (19) connected with the second fly-wheel (17) is mounted rotatably but axially fixedly on the bearing extension (9) and in that the bearing extension (9) is made as a component separate from the first fly-wheel (7) and is disengageably con nected with the first fly-wheel (7) through the second screw connections (11).

3. Fly-wheel according to Claim 2, characterised in that the first screw connections (5) and second screw connections (11) are arranged substantially on a common circle (13), in that the second screw connections (11) penetrate the first fly-wheel (7) and secure the bearing extension (9) through the first fly-wheel (7) on the crank-shaft (3) and in that the bearing extensions (9) is provided with apertures (25) in the region of the first screw connections (5).

4. Fly-wheel according to one of Claims 1 to 3, characterised in that third screw connections (51) secure the damper part of the torsional vibration damper (19), connected with the first fly-wheel (7), to the first fly-wheel (7).

5. Fly-wheel according to Claim 4, characterised in that the side disc (33) adjacent to the first flywheel (7) is screwed to the fly-wheel (7) by means of the third screw connections (51).

6. Fly-wheel according to Claim 5, characterised in that the third screw connections (51a, g; 73, e, f) have engagement parts for screwdrivers accessible on the side of the first fly-wheel (7a, b, e, f, g) axi ally remote from the side disc (33a, b, e, f, g).

7. Fly-wheel according to Claim 6, characterised in that the third screw connections comprise stay bolts (51 b, e, f) held on the side disc (33b, e, f).

8. Fly-wheel according to Claim 7, characterised in that the stay bolts (51f) are riveted to the side disc (33f).

9. Fly-wheel according to Claim 7, characterised in that the stay bolts (51b) have a head (71) welded to the side disc (33b) on the side remote from the first fly-wheel (7b).

10. Fly-wheel according to Claim 7, character ised in that the stay bolts (51e) have a head (71e) guided fast in rotation on a shoulder (93) oif the side disc (33e), on the side remote from the first fly-wheel (7e).

11. Fly-wheel according to Claim 10, characterised in that the shoulder is formed by a material accumulation (93, 97) pressed on the side disc (33e) and in that the head (71e) is secured axially by a peaned-over portion (95) of the material accumulation (93,97).

12. Fly-wheel according to Claim 6, characterised in that the third screw connections comprise collared nuts (103) inserted into the side disc (339).

13. Fly-wheel according to Claim 4, characterised in that the third screw connections (51, h, i, k) secure the intermediate disc (39h, k) or the side disc (33, i) of the torsional vibration damper (19, h, i, k)adjacent to the first fly-wheel (7, h, i, k) and have, on the side of the intermediate disc (39h, k) or of the side disc (33, i) remote from the first flywheel (7, h, i, k), engagement elements for screwdrivers which are accessible through apertures (55, 57, 59) of the second fly-wheel (17, hi, k).

14. Fly-wheel according to Claims 1 to 13, characterised in that the second fly-wheel (17) is secured by means of fourth screw connections (53) on the damper part of the torsional vibration damper (19).

15. Fly-wheel according to Claim 14, characterised in that the second fly-wheel (17) is screwed, on the side of the springs (49) of the torsional vibration damper (19) radially remote from the bearing extension (9), to the intermediate disc (39) ot the axially adjacent side disc (31) of the torsional vibration damper (19), and in that the fourth screw connections (53) comprise engangement parts for screwdrivers which are accessible on the side of the second fly-wheel (17) remote from the first flywheel (7).

16. Fly-wheel according to Claim 15, characterised in that the fourth screw connections comprise stay bolts (53b, c) held on the intermediate disc (39b, c).

17. Fly-wheel according to Claim 16, characterised in that the stay bolts (53b) are riveted to the intermediate disc (39b).

18. Fly-wheel according to Claim 16, characterised in that the stay bolts have a head welded to the intermediate disc on the side remote from the second fly-wheel.

19. Fly-wheel according to Claim 16, characterised in that the stay bolts (53c) have, on the side remote from the second fly-wheel (17c), a head (85) guided fast in rotation in a depression (83) of the intermediate disc (39c).

20. Fly-wheel according to Claim 14, characterised in that the second fly-wheel (17 i, k) is secured by means of screw connections (111; 144) to a flange ring (41i, k) mounted rotatably but axially fixedly on the bearing extension (9i, k)

21. Fly-wheel according to Claim 20, characterised in that a thermal insulating washer (115; 125) is arranged between the second fly-wheel (17i, k) and the flange ring (41i, k).

22. Fly-wheel according to Claim 2, characterised in that at least the second screw connections (11) are formed as necked-down screws and in that the bearing extension (9) is fixed in relation to the first fly-wheel (7) by means of a dowel pin (29) parallel to the axis of rotation and engaging preferably also in the crank-shaft (3).

23. A divided fly-wheel as claimed in Claim I, substantially as described herein with reference to and as illustrated by the embodiments shown in the accompanying drawings.