Rotary shafts – gudgeons – housings – and flexible couplings for ro – Overload release coupling – Torque transmitted via frangible element
Reexamination Certificate
2001-10-16
2004-10-12
Binda, Greg (Department: 3679)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Overload release coupling
Torque transmitted via frangible element
C464S076000, C474S094000
Reexamination Certificate
active
06802779
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a torque transmitting apparatus for transmitting torque from a driving source such as an engine to a rotary device such as an alternator or a compressor disposed within an engine room of a vehicle.
2. Description of Related Art
A rotary device such as a compressor which operates with power provided from an engine undergoes a change in torque fed thereto upon a change in load on the engine. When the torque fed to the rotary device changes, moving components oscillate, with consequent likelihood of noise generation.
The problem may be solved by adopting means such that a torque transfer member formed of an elastic material, that is, rubber, is disposed in a power transfer path extending from a drive source such as an engine up to a rotary device such as a compressor.
In this case, for absorbing a torque variation sufficiently it is desirable that the elastic modulus of the torque transfer member be set small. However, if the elastic modulus is set small, it becomes difficult to transfer a large torque and it is very likely to exceed an elastic limit of the torque transfer member. Thus, the durability of the torque transfer member may be worsened.
In the rotary device such as a compressor or a pump for power steering, required torque required on the rotary device side changes greatly, so that torque acting on a torque transmitting member differs greatly between the case where a torque variation is absorbed in a state in which the required torque is large and the case where a torque variation is absorbed in a state in which the required torque is small.
Therefore, by such a simple way as merely disposing in a power transmission path a torque transmitting member made of an elastic material such as rubber, it is difficult to absorb a torque fluctuation sufficiently in both cases of the required torque being large and small.
SUMMARY OF THE INVENTION
An object of the present invention is to allow a transmission of large torque while absorbing a torque fluctuation to a satisfactory extent.
According to a first aspect of the present invention, a torque transmitting member is deformed mainly by a flexural deformation when the amount of deformation is less than a predetermined amount and is deformed mainly by a compressive deformation when the amount of deformation is more than the predetermined amount. An elastic modulus of the torque transmitting member at a time when an amount of deformation is larger than the predetermined amount becomes larger than that at a time when an amount of deformation is less than the predetermined amount.
Thus, when the transmission torque fed from the driving source to the rotary device is small, the elastic modulus of the torque transmitting member becomes small, so that a fluctuation of the transmitting torque can be absorbed to a satisfactory extent. On the other hand, when the transmitting torque is large, the elastic modulus of the torque transmitting member becomes large, so that the torque transmitting member can be prevented from exceeding its elastic limit.
Thus, not only the transmission of a large torque can be done while absorbing a torque fluctuation sufficiently but also the torque transmitting member can be prevented from exceeding its elastic limit, thereby improving the durability of the torque transfer member.
Here, the elastic modulus of the torque transmitting member represents a change rate, K (=&Dgr;T/&Dgr;&thgr;), of a transmission torque T transmitted between the first rotor and the second rotor relative to a relative rotational angle &thgr; of the first rotor with respect to the second rotor.
According to a second aspect of the present invention, an elastically deformable elastic member is disposed between a first curved surface of first rotor and a second curved surface of second rotor, and the elastic member is compressed by first and second curved surfaces to transmit a torque from the first rotor to the second rotor. A radius of curvature and a center of curvature of the first curved surface and a radius of curvature and a center of curvature of the second curved surface are made different from each other. Therefore, a change rate of the distance between the first and second curved surfaces at a time when a relative rotational angle of the first rotor with respect to the second rotor exceeds a predetermined amount is larger than a change rate of the distance between the first and second curved surfaces at a time when the relative rotational angle exceeds the predetermined amount.
Thus, when the torque is imposed on the first rotor and the first rotor rotates relatively with respect to the second rotor, as the relative rotational angle (&thgr;) increases, the amount of movement of the first curved surface toward the second curved surface increases.
Consequently, the change rate of the distance between the first and second curved surfaces at a time when the relative rotational angle exceeds the predetermined amount becomes larger than that at a time when the relative rotational angle is less than the predetermined amount. In this case, since the elastic member is disposed between the first and second curved surfaces, as the relative rotational angle increases, the amount of compressive deformation of the elastic member in a non-linear fashion increases. That is, the transmission torque transmitted from the first rotor to the second rotor increases in a non-linear manner as the relative rotational angle becomes larger.
Therefore, even if an elastic material having a relatively large elastic modulus is selected as the elastic member, it is possible to decrease the amount of deflection at a relative rotational angle less than the predetermined amount, so that an elastic material having a relatively large elastic modulus can be used for the elastic member.
Further, since it is possible to prevent the elastic member from exceeding its elastic limit when the transmission torque becomes large, it is possible to transmit a large torque while absorbing a torque variation sufficiently.
According to a third aspect of the present invention, an outer periphery of the second rotor is generally star-shaped so as to have a plurality of projections, with a smooth curved surface being formed between adjacent projections, pins each having a circumferential surface with a radius smaller than a radius of curvature of the curved surface are provided in the first rotor so as to be each positioned between adjacent projections. An elastically deformable elastic member is disposed on the curved surface.
Thus, as the relative rotational angle of the first rotor with respect to the second rotor increases, the amount of compressive deformation of the elastic member increases in a non-linear manner. That is, as the relative rotational angle increases, the transmission torque increases in a non-linear manner.
Thus, even if an elastic material having a relatively large elastic modulus is adopted for the elastic member, it is possible to decrease the amount of deflection at a relative rotational angle less than a predetermined value, so that an elastic material having a relatively large elastic modulus can be used for the elastic member.
Further, since it is possible to prevent the elastic member from exceeding its elastic limit when the transfer torque becomes large, it is possible to effect the transfer of a large torque while absorbing a torque variation sufficiently.
According to a fourth aspect of the present invention, a torque transmitting member is deformable elastically and includes first and second transmitting members accommodated within the same space and having respective portions generally parallel to a compressive load direction which are different in size. When a relative rotational angle of the first rotor with respect to the second rotor is less than a predetermined rotational angle, the its first transmitting member mainly transmits the torque by undergoing a compressive deformation. On the other hand, when the relative rotational angle exceeds the pr
Ito Makoto
Kurohata Kiyoshi
Ohguchi Junichi
Saiki Manabu
Tabuchi Yasuo
Binda Greg
Denso Corporation
Posz & Bethards, PLC
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