GB2313898A - Divided flywheel - Google Patents

Abstract

A divided flywheel with two coaxial, relatively rotatable flywheels (3, 11 Fig 1 which can turn relative to each other against the action of swivel centrifugal weights 17 which act between them. The centrifugal weights are a component part of a torsion vibration damper and are mounted to swivel on one of the flywheels and to have a connection 34 with the other of the flywheels. By means of this connection, when there is relative rotation between the flywheels, the centrifugal weights are automatically swivelled about their bearings 18. A torque restricting device 33 is provided in active connection between the two flywheels and is arranged in series with the centrifugal weights 17 which form a torsion vibration damper 16.

Description

DIVIDED FLYWHEEL The invention relates to a divided flywheel with two flywheels arranged coaxial with each other and which can turn relative to each other against the action of swivel centrifugal weights which can act between same. These centrifugal weights form a component part of a torsion vibration damper which is dependent on centrifugal force.

The centrifugal weights are mounted for swivel movement on one of the flywheels and have a connection with the other of the flywheels by means of which during relative rotation between the two flywheels the centrifugal weights are swivelled automatically about their bearing, namely against the turning resistance which is produced as a result of the centrifugal force acting on the centrifugal weights.

Divided flywheels of this kind have been proposed for example through WO 89/01097, WO 92/140476, W094/10477 and WO 94/20769. It is clearly apparent from this prior art that, with divided flywheels operating on the principle already described, there are still considerable problems regarding their damping capacity, functioning and service life The invention is based on the knowledge that with divided flywheels with a functioning principle according to the aforesaid prior art only a very slight turning resistance can be produced between the two flywheels through the centrifugal weights at very low speeds. Since through the attachments of the centrifugal weights with the flywheels a comparatively large turning angle is possible between same before through additional damping means an increased turning resistance comes into action between the flywheels, at least at low speeds and simultaneous appearance of high torque fluctuations or torque shocks the flywheels undergo very high accelerations relative to each other and thus high relative speeds. The energy which is to be absorbed or eliminated between the flywheels can thereby be so large that a damping is not sufficient or not possible through the aforesaid additional damping means and thus even after just a short operating time the entire flywheel is destroyed or no longer able to function reliably at least from the vibration point of view for the use in question. This problem is also apparent from the development which can be drawn from the said prior art. This development shows that the damping means which are provided in addition to the centrifugal weights and which at the same time define the relative rotation between the two flywheels can become more and more expensive during the course of development without however being able to overcome the basic problem, namely an at least partial destruction of the divided flywheel in the event of very high torque shocks.

High torque shocks of this kind can occur for example when starting up and turning off the engine which interacts with a divided flywheel of this kind since then in most cases a resonance area has to be covered. However even with low speeds of the internal combustion engine it is possible as already mentioned that as a result of the only very low damping capacity of the centrifugal weights which then exists large vibration amplitudes can occur, particularly when there is a sudden surge of fuel or a sudden change-over from pulling to pushing operation through a sudden pressure and release on the accelerator pedal. Such driving states have to be absorbed with regard to vibrations by a divided flywheel without damage.

The object of the present invention is to remove the aforesaid disadvantages of the known divided flywheels of the kind already mentioned without dispensing with the principle of vibration damping by means of the centrifugal weights. Furthermore through the invention a simplification of the torsion vibration damper comprising the centrifugal weights is to be ensured so that a simple and cost-effective design of divided flywheels is guaranteed. Furthermore divided flywheels of the kind already mentioned are to be optimized with regard to their wear resistance.

According to the invention this is achieved in that a torque restricting device or slip clutch is provided in active connection between the two flywheels and is arranged in series with the torsion vibration damper comprising the centrifugal weights. Through the design according to the invention it is ensured that the inadmissibly high torque peaks are capped, namely through the torque restricting.

device which can be designed as a slip clutch. The build up in the drive train of extremely high torques is thus suppressed through the torque restricting device so that damage of the divided flywheel, more particularly of the torsion vibration can also not occur. The torque transfer capacity of the device is thereby measured so that this can transfer at least the nominal engine torque, preferably 1.

4 to 3 times. It can however also be expedient if torques are transferable through the torque restricting device which lie above three times the nominal engine torque.

Advantageously one of the flywheels can be connectable with the output shaft of a motor and the second flywheel can be connected through a friction clutch to the input part of a gearbox, wherein it can furthermore be expedient if the centrifugal weights are mounted for turning or swivelling on the second flywheel. In many cases it can however also be advantageous if the centrifugal weights are mounted for rotation on the flywheel connectable with the motor.

According to a further inventive design the centrifugal weights can be connected to their relevant swivel bearing through circumferentially pliable elements. The pliable elements can thereby be designed leaf spring like wherein it can be further advantageous if they form directly the attachment areas for the swivel bearing. Through the action of the centrifugal force friction arises in the swivel bearing which opposes a turning of the centrifugal weights.

The pliable elements are designed so that with small vibrations between the flywheels these are elastically absorbed and damped by the pliable elements so that no movement arises in the bearing itself. The wear in the area of the swivel bearings can thereby be considerably reduced.

In order to ensure that in the event of torsion vibrations of small amplitude between the flywheels these torsion vibrations are always absorbed through the circumferentially resiliently pliable elements additional means such as in particular means producing a friction hysteresis can be provided in the area of the swivel bearings or adjoining the swivel bearings. These means which produce an additional friction hysteresis can be used at the same time to dampen torsion vibrations which extend beyond those which can be absorbed through the elastic means. Furthermore by suitably dimensioning the friction produced through the additional means it is possible to determine the size order of the vibration amplitudes which can be absorbed through the circumferentially resiliently pliable elements without movement taking place in the area of the swivel bearings.

The swivel bearings can advantageously be provided on a component part which serves as an input part or output part of the torque restricting device.

According to a further inventive idea instead of producing the attachment or connection of the centrifugal weights with one of the flywheels by connecting rod type elements it is possible to provide this connection through a slide-like guide. The slide guides provided between the flywheel weights and one of the flywheels can be adapted to the relevant case of use through suitable form of vibration technology. The slide guide of the relevant flywheel weights can thereby be formed symmetrical in both turning directions starting from the theoretical centre position viewed in the circumferential direction - between the two flywheels. It can however also be expedient if a slide guide of this kind is formed non-symmetrical relative to the theoretical centre position so that a different damping characteristic can be achieved through the centrifugal weights in pulling and push operation. Although all the centrifugal weights can interact with a similarly designed slide guide it can also be expedient if different types of slide guides are used regarding the design. The different types of slide guides are preferably arranged symmetrically spread out viewed over the circumference of the divided flywheel.

For the manufacture and functioning of the divided flywheel it can be expedient if the centrifugal weights are formed by substantially flat component parts which can be housed axially between two ring-shaped component parts. In order to form slide like guides the ring-shaped component parts can have circumferentially and radially extending slits in which stud-like guide attachments protruding sideways from the centrifugal weights can engage. Advantageously the two ring-shaped component parts can be positioned relative to each other in an axial spacing which is measured so that a free swivel movement of the centrifugal weights is guaranteed. A particularly simple construction of the divided flywheel can thereby be guaranteed so that the ringshaped component parts are used to form the torque restricting device.

The invention will now be explained with reference to Figures 1 to 6 in which: Figure 1 is a sectional view through a divided flywheel according to the invention; Figure 2 is a sectional view along the line II/II of Figure 1; Figure 3 is a sectional view through a further embodiment of a divided flywheel; Figure 4 is a sectional view according the line IV/IV of Figure 3; Figure 5 is a sectional view through a different divided flywheel designed according to the invention and Figure 6 is a partial illustration of a section along the line VI/VI of Figure 5.

The divided flywheel 1 according to Figures 1 and 2 has a primary flywheel 3 formed substantially by a shaped metal part 2 which is connectable at a radially inner region by screws 4 to the output shaft of a motor. The primary flywheel 3 has a ring-shaped radial area 6 which extends about the rotary axis 5 and supports on its outer circumference an axial attachment 7 on which a starting gear ring 8 is fixed.

The inner region of the primary flywheel 3 supports an axial attachment 9 on which a rolling bearing 10 is housed through which the secondary flywheel 11 is mounted concentric with the primary flywheel 2. The secondary flywheel 11 supports a friction clutch 12 and the friction linings of a clutch disc 15 can be clamped between the pressure plate 13 and the secondary flywheel 11 which is thus formed as a counter pressure plate 14.

A torsion vibration damper 16 is provided between the two flywheels 2 and 11 and its damping characteristic or turning stiffness is dependent on speed or centrifugal force.

The torsion vibration damper 16 has centrifugal weights 17 which are each able to turn about an articulated joint or bearing point 18 like a pendulum. The bearing points 18 are radially remote from the rotational axis 5 and form a rotational axis which runs at least substantially parallel to the rotational axis 5 of the divided flywheel 1.

The swivel bearing of the centrifugal weights 17 on the bearing points 18 is provided by connecting members 19 which in the illustrated embodiment consist of spring steel. The connecting members 19 are made of strip metal which receives its cross-sectional shape shown in Figure 2 by bending. The at least substantially radially aligned arms 20 of a connecting member 19 lie one on the other and are fixedly connected to a centrifugal weight 17 by rivetting at their radially outer free end. Radially inside, the connecting members 19 each form an eyelet 21 which is placed about an axis of articulation 22.

The articulation axes 22 are in the illustrated embodiment formed by rivet elements which connect two ring-shaped component parts 23, 24 fixedly together. The ring-shaped component parts 23, 24 are placed on top of each other radially inside the rivet elements 22. In the illustrated embodiment only the left ring-shaped component part 23 has an inner area which is displaced axially in the direction of the right ring-shaped component part 24 so that their inner areas 25, 26 adjoin one another axially. The radially outer ring-shaped areas 27, 28 are held axially spaced by means of the rivet elements 22. The connecting members 19 are housed with swivel movement between the ring-shaped areas 27, 28.

The radially inner areas 25, 26 are mounted rotatable centred on an axial extension 29 of the secondary flywheel 11. Furthermore an axially tensioned energy accumulator in the form of a plate spring 30 is housed on the axial attachment extending axially in the direction of the primary flywheel 3 and is supported radially inwards on a security element 31 and radially outwards biases the ring-shaped area 25. The ring-shaped component part 24 is supported axially on a surface 32 supported by the secondary flywheel 11. The ring-shaped areas 25, 26 are tensioned axially between the surface 32 and plate spring 30 through the axial pretension of the plate spring 30 whereby a friction engagement exists between the ring-shaped component parts 23, 24 and the secondary flywheel 11. This friction engagement is measured so that between the two flywheels 3, 11 at least the nominal torque, preferably 1. 5 to 3 times the nominal torque of the internal combustion engine driving the primary flywheel 3 can be transferred slip-free.

The energy accumulator 30 as well as the ring-shaped component parts 23, 24 are thus a constituent part of a torque restricting device or a slip clutch 33 which in the illustrated embodiment is supported by the secondary flywheel mass 11 and is arranged actively in series with the torsion vibration damper 16. The component parts 23, 24 thus form in practice the input part of the torque restricting device 33.

The flat centrifugal weights 17 are each attached to the primary flywheel 3 by connecting rod like elements or levers 34. With the illustrated embodiment two levers 34 are provided for each centrifugal weight 17 and are fixedly connected on one side through a bearing point 35 for articulation with one centrifugal weight 17 and on the other side through a bearing point 36 for articulation with the primary flywheel 3. The bearing points 35 are radially outside of the bearing points 18, namely as can be seen from Figure 2 in the theoretical neutral angular position between the two flywheels 3, 11 on the same radial line starting from the rotational axis 5. Furthermore it can be seen from Figure 2 that the bearing points 35, 36 are arranged at least approximately on the same diameter. The bearing point 36 comprises a rivet element which extends axially, is fixedly rivetted to the primary flywheel 3 and forms an articulation axis 37 on which a lever 34 is mounted for swivel or rotational movement. A spacer sleeve 38 is provided axially between the two levers 34 and has at least substantially the same thickness as the areas of a centrifugal weight housed between the levers 34.

The bearing point 35 likewise comprises a connecting element in the form of a rivet 39 which secures the levers 34 arranged either side of a centrifugal weight 17 axially relative to each other and forms an articulation axis 40 which supports a centrifugal weight 17 for swivel or rotary movement relative to the levers 34.

In order to reduce the wear in the area of the bearing points 18, 35, 36 it is possible to provide bearing means, such as slide bearings or needle bearings between the component parts which can move relative to each other.

The torsion vibration damper 16 has the following basic method of operation. When the divided flywheel 1 is turning, the centrifugal weights tend to move radially outwards under the centrifugal force which acts on them. The weights therefore move into a stable position or into the basic position shown in Figure 2, or into a neutral position between the two flywheels 3, 11 which is the position these flywheels occupy if the torque being transferred through the divided flywheel I is not large enough to displace the centrifugal weights from this position. As soon as a torque is introduced through the divided flywheel 1 which is large enough to turn the two flywheels 3, 11 relative to each other, the centrifugal weights 17 are forced into a different angular position relative to the bearing point 18, and this angular position is dependent on the balance between on the one hand the turning resistance of the centrifugal weights 17 about the bearing points 18 which results from the existing speed and the centrifugal force thereby acting on the centrifugal weight, and on the other hand the torque turning the two flywheels relative to one another. With this balance it is also necessary to take into account the amount of centrifugal force which arises which acts for example on the levers and is radially supported on the centrifugal weights 17. The significant proportion of the centrifugal forces is however produced by the centrifugal weights. The turning resistance between the two flywheels 3, 11 is thus substantially a result of the centrifugal force acting on the centrifugal weights 17 which opposes a turning of the centrifugal weights 17 about their relevant bearing position 18 since through such turning the centre of gravity of the centrifugal weights 17 is forced radially inwards thus to a smaller radius. For a more detailed description of the function of the torsion vibration damper 16 reference is made to the prior art already mentioned.

The torque restricting device 33 acting in series with the torsion vibration damper 16 acts so that the extremely high torque shocks or torque fluctuations which normally occur between the two flywheels 3, 11 are capped with regard to their amplitude so that a destruction of the divided flywheel 1 or the assembly connected therewith can be avoided.

The design according to the invention furthermore has the advantage that through the circumferentially resiliently pliable connecting members 19 small angular vibration amplitudes between the two flywheels 3, 11 can be absorbed and compensated so that with small vibrations of this kind no movement takes place and thus the wear occurring in the area of these bearing points 18 throughout the service life can be at least considerably reduced. The elastic pliability or spring rate of the radial arms 20 of the connecting members 19 is thereby measured so that at least at higher speeds where high-frequency torsional vibrations arise with small amplitude between the two flywheels 3, 11 the friction in the area of the bearings points 18 is sufficiently large to prevent swivelling of the centrifugal weights 17 in the bearing points 18 whereby the required angular compensation takes place through the resilient arms 20. The aforesaid torsional vibrations of low amplitude can be in the range from 0. 5 to 5 degs. In most cases these angular deflections between the two flywheels 3, 11 are in the order of 0. 5 to 2 degs. However smaller or larger angular vibration amplitudes can also occur. The elastic deformation of the connecting members 19 described above is particularly advantageous at speeds above 1000 revolutions per minute.

For many cases however it can also be expedient to provide an additional turning resistance between the connecting members 19 and their bearing points 18 so that even at lower speeds, where applicable even at idling speed, it is ensured that for small angular vibration amplitudes between the two flywheels 3, 11 the elastic damping takes place through the connecting springs 19. In Figure 1 an energy accumulator is provided in the form of a plate spring 41 which is mounted in the area of the bearing points 18 and is axially tensioned between the connecting members 19 and the annular component part 23. An additional turning resistance is thereby produced which is created by friction and which is superimposed on the turning resistance existing in the bearing points 18. The arms 20 of the connecting members 19 are formed leaf spring like so that they resiliently bend in the circumferential direction.

The design according to Figures 3 and 4 likewise has a primary flywheel 3 and a secondary flywheel 11 which are rotatable relative to each other concentric about a rotary axis 5 through a bearing 10.

A torque restricting device 133 and a torsion vibration damper 116 connected in series therewith is provided between the two flywheels 3, 11. The torsion vibration damper 116 has centrifugal weights 117 which can each carry out pendulum vibrations about an articulated joint or about a bearing point 118.

A bearing point 118 has an articulation axis 122 on which a centrifugal weight 117 is mounted for swivel movement. The articulation axis 122 is connected to two ring-shaped component parts 123,124, as with the articulation axis 22 according to Figures 1 and 2. The ring-shaped component parts 123, 124 are however connected rotationally secured to the secondary flywheel 11 through connecting means in the form of rivets 132. Viewed in the torque flow from the primary flywheel 3 to the secondary flywheel 11 the torque restricting device is connected in front of the torsion vibration damper 116 in the form of a slip clutch 133.

The control or turning of the centrifugal weights 117 is provided by a slide guide 134. The slide guide 134 comprises slides 135 which are fitted in the ring-shaped component parts 136 arranged either side of the centrifugal weights 117. The ring-shaped component parts 136 are held axially at a defined distance through spacer rivets 137.

The distance is thereby measured so that the centrifugal weights 117 can be moved between the component parts 136.

The centrifugal weights 117 each have axially protruding studs 138 which are guided in the associated slide guides 135. The slide guides 135 are formed so that with relative turning between the two flywheels 3, 11 from the theoretical neutral position shown in Figure 4 the centre of gravity of the centrifugal weights 117 is forced radially inwards against the centrifugal force acting during rotation on the centrifugal weights 117. With the illustrated embodiment the slide guides 135 are formed symmetrical in both relative turning directions between the flywheels 3, 11 starting from the position shown in Figure 4. These slide guides can however also be formed non-symmetrical to achieve a nonsymmetrical damping. Also by suitably shaping of the slide guides 135 it is possible to adapt the damping caused by the centrifugal weights 117 to each relevant use. Thus for example the slide guides can also be formed curved at least over partial areas of their extension. The damping action of the torsion vibrations damper 116 can thus be formed variable over the relative turning angle between the two flywheels 3, 11 through corresponding design of the slides 135.

The studs 138 of a centrifugal weight 117 engaging in the slides 135 can be formed by a component part 139 mounted rotatable in the centrifugal weight 117. It can thereby be ensured that the studs 138 can roll on the contours defining the slides 135 whereby at least the wear on the studs 138 can be considerably reduced.

The ring-shaped component parts 136 are a constituent part of the slip clutch 133. The component parts 136 are clamped axially between on one side a radial support area 140 at the free end of the ring-shaped area 107 of the primary flywheel 3 and on the other side the plate spring 141. The plate spring 141 is provided between the radial area 106 of the primary flywheel 3 and the ring-shaped component part 136 adjoining same. The ring-shaped component parts 136 are biased axially in the direction of the radial support 140 by pretensioning the plate spring 141. The plate spring 141 is measured so that the friction moment produced by same is greater than the nominal torque provided by the motor driving the primary flywheel 3. The torque transferable through the torque restricting device 133 is preferably 1.5 to 3 times the nominal engine torque. It can however also be expedient to make the torque capacity of the slip clutch 133 greater.

The embodiment according to Figures 5 and 6 has a similar construction to the design according to Figures 1 and 2.

Thus a primary flywheel 3 and a secondary flywheel 11 rotatable relative to same are provided wherein a torsion vibration damper 16 and a torque restricting device 33 connected in series therewith are provided between the two flywheels. The embodiment according to Figures 5 and 6 differs basically in that an additional damper stage 242 is provided between the two flywheels 3, 11 and its action over partial areas of the relative turning angle between the two flywheels 3, 11 is connected in parallel with the damping action of the centrifugal weights 17. The damper stage 242 connected in series with the torque restricting device 33 has energy accumulators in the form of coil springs 243 which are provided in sockets or in windows 244, 245 which are provided on the primary flywheel 3, as well as in sockets 246 which are formed by the ring-shaped component parts 223, 224 forming the input part of the slip clutch 33.

The relative turning between the ring-shaped component parts 223, 224 and the primary flywheel 3 can be produced at least during a pulling operation through the windings of the springs 243 becoming blocked. Advantageously the damper stage 242 can be designed so that it is active over an angular area which lies in the order of 20 to 90% of the relative turning angle allowed by the attachment of the centrifugal weights 117 between the two flywheels 3, 11.

Advantageously the damper stage 242 can also become operative during push operation or at least one additional damper stage 247 can be used for the push operation which likewise has energy accumulators 248, eg of rubber. The additional damping device with energy or force accumulators acting in pull operation and/or push operation can also be formed multi-staged.

The patent claims filed with the application are proposed wordings without prejudice for achieving wider patent protection. The applicant retains the right to claim further features disclosed up until now only in the description and/or drawings.

References used in the sub-claims refer to the further design of the subject of the main claim through the features of each sub-claim; they are not to be understood as dispensing with obtaining an independent subject protection for the features of the sub-claims referred to.

The subjects of these sub-claims however also form independent inventions which have a configuration independent of the subjects of the preceding sub-claims.

The invention is not restricted to the embodiment of the description. Rather numerous modifications and alterations are possible within the framework of the invention, more particularly those variations, elements and combinations and/or materials which are inventive for example through combination or modification of individual features or elements or method steps contained in the drawings and described in connection with those in the general description and embodiments and claims and lead through combinable features to a new subject or to new method steps or sequence of method steps where they relate to manufacturing, testing and work processes.

Claims (12)

PATENT CLAIMS

1. Divided flywheel with two flywheels arranged coaxially relative to each other which can turn relative to each other against the action of swivel centrifugal weights which act between same wherein the centrifugal weights are a component part of a torsion vibration damper and are mounted to swivel on one of the flywheels and have a connection with the other of the flywheels and by means of this connection during rotation between the two flywheels the centrifugal weights are automatically swivelled about their bearing characterised in that a torque restricting device is provided in active connection between the two flywheels and is arranged in series with the torsion vibration damper comprising the centrifugal weights.

2. Divided flywheel according to claim 1 characterised in that one of the flywheels is connectable with the output shaft of a motor and the second flywheel is connectable through a friction clutch with the input shaft of a gearbox and the swivel bearings of the centrifugal weights are supported by the second flywheel.

3. Divided flywheel more particularly according to claim 1 or 2 characterised in that the flywheel weights are connected to their relevant swivel bearings through circumferentially resilient pliable elements.

4. Divided flywheel according to claim 3 characterised in that the stiffness of the circumferentially resilient elements in relation to the turning resistance which exists in the area of the swivel bearings or can be produced by friction is measured so that torsion vibrations of small amplitude between the flywheels are absorbed through the elasticity of the circumferentially resilient elements.

5. Divided flywheel according to one of claims 1 to 4 characterised in that the swivel bearings are provided on a component part which serves as an input part or an output part of the torque restricting device.

6. Divided flywheel more particularly according to one claims 1 to 5 characterised in that the connection of a flywheel weight with one of the flywheels is provided through a slide guide.

7. Divided flywheel according to claim 6 characterised in that the slide guide is formed symmetrical in both turning directions starting from the theoretical centre position viewed in the circumferential direction - between the two flywheels.

8. Divided flywheel according to claim 6 characterised in that the slide guide is formed non-symmetrical in both turning directions starting from the theoretical centre position - viewed in the circumferential direction - between the two flywheels.

9. Divided flywheel according to one of claims 6 to 8 characterised in that the centrifugal weights formed substantially as a flat component part are housed axially between two ring-shaped component parts which have to form the slide-like guides circumferentially and radially extending slits in which stud-like projections engage protruding laterally from the flat centrifugal weights.

10. Divided flywheel according to claim 9 characterised in that the two ring-shaped component parts are positioned relative to each other at an axial spacing which ensures free swivel movement of the centrifugal weights.

11. Divided flywheel according to one of claims 9, 10 characterised in that the ring-shaped component parts are a constituent part of the torque restricting device.

12. Divided flywheel substantially as herein described with reference to the accompanying drawings.