Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
1999-03-05
2001-04-17
Dayoan, B. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C464S064100, C464S067100, C464S066100
Reexamination Certificate
active
06217451
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to dampers in general, and more particularly to improvements in torsional vibration dampers which can be utilized in the power trains of motor vehicles, for example, to at least partially absorb shocks between the rotary output element of a prime mover (such as the camshaft or crankshaft of an internal combustion engine) and the housing of a friction clutch which is engageable to transmit torque to the rotary input element of a change-speed transmission. Still more particularly, the invention relates to improvements in torsional vibration dampers wherein an input member and an output member are rotatable with each other about a common axis as well as relative to each other against the opposition of one or more energy storing devices.
Commonly owned U.S. Pat. No. 5,377,796 (granted Jan. 3, 1995 to Oswald Friedmann et al. for “APPARATUS FOR TRANSMITTING FORCE BETWEEN ROTARY DRIVING AND DRIVEN UNITS”) discloses a hydrokinetic torque converter wherein a torsional vibration damper is installed in a composite flywheel, namely between a primary flywheel which receives torque from the crankshaft or camshaft of an internal combustion engine and a secondary flywheel which drives the housing and the pump of the torque converter. The damper comprises a rotary input member which includes or is driven by the primary flywheel, a rotary output member which includes or drives the secondary flywheel, and an energy storing device which opposes rotation of the input and output members relative to each other. The energy storing device comprises at least two coil springs one of which is confined in the other. The length of the one coil spring matches or approximates that of the other coil spring.
U.S. Pat. No. 5,367,919 discloses a similar torsional vibration damping apparatus which also comprises coaxial primary and secondary flywheels and an energy storing device serving to oppose rotation of the flywheels relative to each other. The secondary flywheel can be coupled to the input shaft of a change-speed transmission by an engageable and disengageable friction clutch. The two flywheels carry spring-engaging portions which cause the energy storing device to store energy, or to store additional energy, when the two flywheels are caused to turn relative to each other.
The disclosure of each patent application and/or patent identified in this specification is incorporated herein by reference. This includes our German priority application Serial No. 198 09 894.4 filed Mar. 7, 1998.
A drawback of many presently known torsional vibration dampers is that they are too bulky, too expensive and/or insufficiently versatile. Moreover, the springs (such as coil springs) of energy storing devices in such conventional torsional vibration dampers are not, or cannot be, used to capacity under all circumstances of use which arise in the power train of a motor vehicle or in other fields in which the utilization of one or more torsional vibration damping apparatus is advisable or necessary.
OBJECTS OF THE INVENTION
An object of the invention is to provide a novel and improved energy storing device for use in torsional vibration dampers.
Another object of the invention is to provide a novel and improved combination of springs which can be employed in the energy storing devices of torsional vibration dampers for use in composite flywheels, between the engine and the clutch in the power train of a motor vehicle, and/or for many other purposes.
A further object of the invention is to provide a torsional vibration damper with one or more energy storing devices which is or are more versatile than heretofore known energy storing devices and which can be put to use under circumstances likely to vary within a wide range, e.g., while a motor vehicle is pulling a load, is idling or is coasting.
An additional object of the invention is to provide a torsional vibration damper with one or more energy storing devices which can be mass produced at a reasonable cost in available machinery and which can be utilized as a superior substitute for presently known energy storing devices.
Still another object of the invention is to provide an energy storing device which can be readily designed and/or modified to be put to optimal use under widely different circumstances.
A further object of the invention is to provide an energy storing device which is constructed and assembled in such a way that its characteristics (particularly its resistance to rotation of the input and output members of a torsional vibration damper relative to each other) can readily and accurately and optimally conform to the circumstances of use of the torsional vibration damper.
Another object of the invention is to provide an energy storing device which can be readily designed to offer different resistances during different stages of rotation of the input and output members of a torsional vibration damper relative to each other.
An additional object of the invention is to provide a torsional vibration damping device whose inertia is low and wherein such desirable feature is attributable, at least in part, to a novel design of its energy storing device or devices.
Still another object of the invention is to provide a power train which embodies at least one torsional vibration damper and at least one energy storing device of the above outlined character.
A further object of the invention is to provide a novel and improved method of assembling the springs of an energy storing device for use in a torsional vibration damper.
An additional object of the invention is to provide a novel and improved method of configurating the input and/or the output member of a torsional vibration damper.
SUMMARY OF THE INVENTION
One feature of the present invention resides in the provision of a torsional vibration damper which comprises input and output members rotatable with and relative to each other in clockwise and counterclockwise directions about a predetermined axis and respectively include at least two first and at least two second stressing components in the form of shoulders, arms, pockets or the like. The improved damper further comprises at least one energy storing device which is arranged to oppose rotation of the input and output members relative to each other. The energy storing device has first and second ends each abutting one of the first and one of the second stressing components, and such ends are spaced apart from each other in the circumferential direction of the input and output members. The novel and improved energy storing device comprises a first coil spring between the ends of the energy storing device, and a second coil spring confined at least in part in an arcuate space defined by the first coil spring. The two coil springs have a common arcuate axis and the first and second coil springs respectively include or consist of a plurality of first and second helical convolutions. At least one of the first convolutions cooperates with at least one of the second convolutions to compel the at least one second convolution to share movements of the at least one first convolution in at least one of the aforementioned (clockwise and counterclockwise) directions.
The at least one first convolution and the at least one second convolution can overlie each other in a plane which is at least substantially normal to the common axis of the coil springs, and such plane can include the common axis of the input and output members.
In accordance with one presently preferred embodiment, the first convolutions can have identical or practically identical inner diameters, and the cooperation between the first and second coil springs is or can be arrived at in that the at least one second convolution has a radially outermost portion which is spaced apart from the common axis of the coil springs by a distance exceeding one-half of one of the inner diameters, i.e., the at least one second convolution is in frictional or force-locking or form-locking engagement with the at least one first convolution.
The at least one first convoluti
J{overscore (a)}ckel Johann
Kooy Ad
Mende Hartmut
Raimann Andreas
Darby & Darby
Dayoan B.
Dunwoody Aaron
LuK Lamellen und Kupplungsbau GmbH
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