Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
2000-04-13
2001-10-09
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C464S062100, C464S066100, C192S070170, C192S214000
Reexamination Certificate
active
06299541
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a double flywheel vibration damper, notably for use in a motor vehicle, for example of the type of those described in the documents FR-A-2 736 116 and EP-A-0 798 490.
DESCRIPTION OF THE PRIOR ART
In these types, the double flywheel includes two mobile coaxial masses free to rotate with respect to each other and acting against elastic parts.
One of the masses, referred to as the first mass, is intended to be fastened to a drive shaft, such as the engine crankshaft of the vehicle, whereas the other mass, referred to as the second mass, is intended to be connected in a disengageable manner to a driven shaft such as the gearbox input shaft. The first mass carries the second mass rotationally on a hub equipped with bearing means, the bearing being located between the hub and the second mass.
The hub projects axially in the direction of the second mass, which is thereby offset axially with respect to the first mass.
Said elastic parts are mounted between the two masses and form part of an elastic torsion-absorbing coupling between the first mass and the second mass.
The hub extends centrally at the inner edge of the first mass.
In the document FR-A-2 736 116 the action of the elastic parts is circumferential. In the document EP-A-0 798 490 the action of the elastic parts elastic parts is radial.
We see therefore that there are several known types of double flywheel vibration damper systems.
SUMMARY OF THE INVENTION
However, it can be useful to be able to fit any type of double flywheel vibration damper on the end of a drive shaft, such as a crankshaft. The purpose of the present invention is to respond to this need in a simple and cost-effective manner.
According to the present invention this problem is resolved by the fact that the hub is formed of two coaxial parts axially aligned, namely a first hub that supports rotationally the second mass on bearing means mounted on this first hub, and a second hub that forms an axial spacer between the drive shaft and said first hub.
The invention is therefore a double flywheel vibration damper including two coaxial masses free to rotate relative to each other and acting against elastic parts, in which one of the masses, referred to as the first mass, is intended to be fastened to a drive shaft, whereas the other mass, referred to as the second mass, includes a reaction plate assuring rotational connection to a driven shaft, and in which said first mass has a central hub projecting axially and carrying bearing means operating between said second mass and said central hub to enable said second mass to rotate on said first mass, wherein said central hub comprises two aligned coaxial parts, namely a first hub supporting said second mass rotationally via said bearing means fitted on this first hub, and a second hub intended to be fastened to said drive shaft, and wherein said second hub constitutes an axial spacer between said drive shaft and said first hub.
The advantage of the invention is that said first hub prolongs said second hub, which means that it is possible to fit on the second hub any type of double flywheel vibration damper equipped with the first hub.
This second hub allows the drive shaft to be shortened and the hub can be made of a much less expensive material than that of the drive shaft, for example a crankshaft, which is forged and machined. This second hub penetrates inside the crankcase of the internal combustion engine.
The solution is therefore simple and inexpensive.
Advantageously the second hub has on its outer edge, in axial succession: a recess, a first throat and a second throat larger than the first throat.
The recess, in contact with a fixed wall, such as the wall of the engine crankcase, can be used to house a seal between this wall and the second hub. This dynamic seal is in rotational contact with the second hub and prevents oil leakage from the engine. The first throat serves to recover any oil leaking from the engine. The second throat serves to collect any particles and leaked liquid arriving radially from the outside.
The second mounting hub therefore also serves as an anti-pollution hub and a hub for rotational contact with the seal mounted on the fixed wall.
In a variant of the invention, the second hub carries the rotor of an electric machine. This electric machine also includes a stator mounted coaxially relative to the rotor. The rotor and the stator are mounted radially one above the other.
In an embodiment, the stator surrounds the rotor. The stator is carried by a fixed support part, with second bearing means between said support part and said second hub.
In this manner, the stator is positioned relative to the rotor, and the stator/rotor air-gap is precisely defined.
The stator includes windings, so the electric machine, of the synchronous or asynchronous motor type, can provide a starter or alternator for the motor vehicle.
This electric machine allows vibrations to be filtered, and the double flywheel vibration damper can be rudimentary, since the angular movements of the elastic parts of this flywheel are smaller. Thanks to the second hub carrying the rotor, efficient filtering of the vibrations is achieved thanks to the inertia of the system.
The electric machine allows the internal combustion engine of the motor vehicle to be accelerated or braked.
The electric machine allows the vehicle's engine to be stopped at traffic lights and to be restarted. For more details, see for example the document WO 98/05882.
The second hub can of course carry the rotor of the machine and have a recess and a first throat, since the rotor is carried, in one embodiment, by a second web of sinuous profile mounted near the free end of the second hub, in other words at some distance from the drive shaft. The second hub may therefore have, in axial succession: the recess, the first throat, the second bearing means (such as a ball bearing), and the second sinuous web.
Thanks to the invention, the double flywheel can be fitted with a transversal metal support plate associated with the first hub and the plugs described in the document FR-A-2 736 116 are eliminated (these plugs located opposite pins fixed to the second mass serve to drive rotationally a friction ring carried by the first mass and forming part of the axially acting friction means).
In one embodiment, the second hub presents at its free end a rim extending over the aforementioned holes to block them.
The side of this rim facing the fixed wall advantageously constitutes one lateral face of the second throat. The friction face of the reaction plate forming part of the second mass is thereby well protected by the second hub. The same applies for the axially acting friction means and the parts inside the first mass. In a variant, the face of the free end of the second hub blocks the aforementioned holes.
The presence of the aforementioned holes is obviously not mandatory. For example, the double flywheel could be equipped with pieces of plate assembled by riveting.
Advantageously the support plate is fixed to the first hub to form a subassembly constituting the double flywheel vibration damper, and the second hub provides a bearing surface for this support plate. In a variant, the first hub has a web providing a bearing surface for the support plate.
In one embodiment the first hub has a transversal shoulder providing a bearing surface for the support plate.
It is this subassembly, forming a module, that is placed on the second hub with formation of an annular channel open towards the outside between the fixed wall and support plate extending parallel to the fixed wall. The bottom of this channel is formed by the second hub. A single series of fastening parts can be used to fasten the two hubs to the drive shaft, although it is advantageous to provide two series of fastening parts.
The two series of fastening parts alternate circumferentially. In a variant, they are located on circles of different diameter.
The first series of fastening parts serves to fix the aforementioned subassembly to the sec
Bertin Patrice
Fenioux Daniel
Grieco Giovanni
Browne Lynne H.
Dunwoody Aaron
Liniak, Berenato, Longacre & White LLC
Valeo
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