Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
1998-12-04
2001-02-13
Knight, Anthony (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S070170, C464S098000
Reexamination Certificate
active
06186898
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns an elastic coupling device between two aligned or substantially aligned shafts, respectively a driving shaft and a driven shaft, said device including circumferential action spring damper means mechanically disposed between the two shafts.
2. Description of Related Art
A device of the above kind is described in document FR-A-2 385 940, for example. In that document the coupling device is mounted between the crankshaft of the engine of a motor vehicle and the input shaft of a transmission, referred to as the transmission shaft.
The device includes a solid hub with internal splines force-fitted onto the transmission shaft and an external annular flange connected to the crankshaft by a drive plate. The hub extends axially in the opposite direction to the crankshaft.
Two guide washers on respective opposite sides of the flange are fixed to the hub. Springs mounted in facing housings in the guide washers and the flange elastically couple the flange to the guide washers.
The above solution is not entirely satisfactory because of its relatively large overall size in the axial direction. Also, it uses a large number of components. In document U.S. Pat. No. 2,787,896 the elastic coupling device has a greater overall axial size at its inside periphery. The axial overall size is large because the guide washers are fixed externally to an axially oriented annular rim on a plate.
SUMMARY OF THE INVENTION
An aim of the present invention is to provide a simple and economic way to overcome the above drawbacks.
In accordance with the invention an elastic coupling device of the above kind is characterised in that the drive plate is constrained to rotate with one of the guide washers, referred to as the first guide washer, while the flange is fastened, possibly after taking up circumferential play, to the hub, in that the hub is directed axially towards the first guide washer, in that the first guide washer carries the other guide washer, referred to as the second guide washer, fixed to its outside periphery, and in that said device is thicker at its outside periphery than at its inside periphery.
The invention considerably reduces the axial overall size of the device. Also the flange has a reduced radial overall size and is therefore more economical.
A starter ring gear and an inertia weight can therefore be installed radially beyond the flange to increase the inertia for the same radial overall size.
The first washer then carries rivets for fixing the second guide washer passing axially through said ring gear and said weight.
The starter ring gear and the inertia weight therefore form a spacer between the guide washers.
In an alternative embodiment the guide washers are in contact with the outside periphery and the rivets pass through the starter ring gear, the contacting parts of the guide washers and the inertia weight so that the guide washers are gripped between the inertia weight and the starter ring gear.
The rivets can of course be replaced by nut and bolt fixings or any other assembly means. In an alternative embodiment the guide washers are identical at their outside periphery and are joined face to face by virtue of being fastened together by a weld bead. One of the washers carries the inertia weight and the other carries the starter ring gear.
By virtue of the invention the elastic coupling device provides additional functions, in particular starting functions, in a simple and economic manner.
The device can have the weight required for good filtration of vibration.
In one embodiment the second guide washer is shorter in the radial direction than the first guide washer. To be more precise, the central opening of the second guide washer has a diameter greater than that of the first guide washer.
Because of this the axial overall size of the elastic coupling device can be further reduced as the flange can have a tortuous shape with a first internal portion at the level of the second guide washer offset axially relative to a main second portion between the two guide washers.
In one embodiment the first guide washer is in one piece with the drive plate, which economises one component.
The first guide washer can be fixed using fixing screws the heads of which are disposed axially between the first guide washer and the flange. The flange then has holes for access to the screw heads for turning them by means of a tool such as a screwdriver.
In a second embodiment the first guide washer surrounds the drive plate and is connected to it by elastic tongues in the axial direction.
Axial vibrations from the crankshaft of the engine of the vehicle, which is subject to axial oscillations, can therefore be damped (filtered).
Clearly the drive plate is then reduced to a simple washer and the first guide washer is rotationally connected to the drive plate but able to move axially relatively to it because of the tangential tongues.
Such damping can equally be obtained by making the first guide washer flexible, for example by providing holes in it.
In one embodiment the hub is in one piece with the flange of meshing means with circumferential play between the hub and the flange. In an alternative embodiment the hub is separate from the flange. The free end of the hub can be chamfered to enter the interior of the driving shaft.
Clearly, by virtue of the invention the elastic coupling device forms a unitary module of small axial overall size that can be tested and balanced dynamically in advance, before it is fixed to the driving shaft.
To this end the first guide washer has at its inside periphery first fixing means for fixing it directly or indirectly to the driving shaft and, radially beyond said first fixing means, second fixing means for fixing the second guide washer.
REFERENCES:
patent: 2787896 (1957-04-01), Jumisco
patent: 4828533 (1989-05-01), Focqueur et al.
patent: 4908003 (1990-03-01), Kobayashi et al.
patent: 4928486 (1990-05-01), Despres
patent: 5194044 (1993-03-01), Jackel et al.
patent: 5253740 (1993-10-01), Kohn et al.
patent: 5551318 (1996-09-01), Fukushima
patent: 5617940 (1997-04-01), Fukushima et al.
patent: 5778738 (1998-07-01), Takabayashi et al.
Knight Anthony
Liniak Berenato Longacre & White
Thompson Kenneth
Valeo
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