Machine element or mechanism – Elements – Flywheel – motion smoothing-type
Patent
1997-01-21
1998-06-09
Luong, Vinh T.
Machine element or mechanism
Elements
Flywheel, motion smoothing-type
74574, 74572, 464 66, F16F 1510
Patent
active
057619697
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a torsional vibration damper for use, for example, in damping the torsional vibrations of an engine crankshaft.
BACKGROUND OF THE INVENTION
It is known to provide a torsional vibration damper for an engine crankshaft in which a rotary body incorporates steel springs interconnecting inner and outer body members for relative rotation with a desired stiffness. Damping is achieved by pumping engine oil between different cavities within the damper construction. Such dampers may require the complex assembly of many precision machine parts which makes them inherently expensive.
Our U.K. Patent Application No.92 24489 describes a torsional vibration damper comprising:
an annular driven member,
an annular inertia member, co-axial with said driven member and capable of limited rotational movement relative thereto,
means fixed to said driven and inertia member means for forming at least one set of variable volume chambers arranged so that relative movement of said driven and inertia members in a first direction decreases the volume of one of said chambers and increases the volume of the other, relative movement in the opposite direction causing a reverse variation in the volume of said chambers,
means for forming at least one annular spring carried by one of said members, and
means for connecting said variable volume chambers to at least one side of said annular spring, said damper being supplied with a source of fluid in said chambers whereby relative rotational movement of said members pressurizes the one side of said annular spring means to cause it to flex in a circumferential direction.
In our previously proposed torsional vibration damper in accordance with the aforesaid patent application the pressure of the damping fluid in the region of the fluid inlets of the variable volume chambers may fall to the vapour pressure of the fluid. Any resulting vapour will interfere with pressurisation of the annular spring means and possibly prevent it flexing thereby rendering the damper ineffective. In addition, turbulent flow of damping fluid in the damping passages requires large pressure changes across the damping passages to sustain the flow, which may lead to local vapour pockets forming when the pressure drops below the vapour pressure. Finally, damping fluid can only flow into the variable volume chambers when the pressure therein is below the supply pressure and the proportion of the cycle time in which this occurs is severely limited.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a torsional vibration damper in which the above disadvantages are obviated or mitigated.
According to the present invention there is provided a torsional vibration damper comprising:
an annular driven member,
an annular inertia member, co-axial with said driven member and capable of limited rotational movement relative thereto,
means fixed to said driven and inertia members for forming at least one set of variable volume chambers arranged so that relative movement of said driven and inertia members in a first direction decreases the volume of one of said chambers and increases the volume of the other, relative movement in the opposite direction causing a reverse variation in the volume of said chambers,
means for forming at least one annular spring carried by one of said members, and
means for connecting said variable volume chambers to at least one side of said spring means, said damper being supplied with a source of fluid in said chambers whereby relative rotational movement of said members pressurizes the one side of said spring means to cause it to flex, characterised in that
at least one of said chambers is provided with inlet and outlet valves so as to enable it to pump fluid from the source to the pressurized side of the spring.
Preferably, the spring means comprises two annular springs connected to respective pumping chamber sets for flexing the springs alternately in a circumferential direction during said relative movement of said driven and
REFERENCES:
patent: 3730457 (1973-05-01), Williams
patent: 3837182 (1974-09-01), Kulhavy
patent: 4905807 (1990-03-01), Rohs et al.
patent: 4944279 (1990-07-01), Woodard
patent: 5048658 (1991-09-01), Reik
patent: 5152189 (1992-10-01), Miura et al.
Luong Vinh T.
Simpson Industries Inc.
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