POWER TRANSMISSION SYSTEM AND ATTENUATION MECHANISM
FIG5 is a schematic diagram of an attenuation mechanism according to the modification and another modification  FIG6 is a schematic diagram of an attenuation mechanism according to yet another modification
In the aforementioned preferred embodiment, the support member 71 of the attenuation mechanism 7 is formed by a single plate. However, the configuration of the support member 71 is not limited to this. For example, as shown in FIG5, the support member 71 may be composed of two or more members. Detailedly, the support member 71 includes an attachment hub 71a and a plate portion 71b. The plate portion 71b is attached to a flange portion 71d of the attachment hub 71a by, for instance, at least one rivet 75. In the aforementioned preferred embodiment, the inertia member 72 is engaged by friction with the support member 71 through the friction materials 73. However, the configuration that the inertia member 72 is engaged by friction with the support member 71 is not limited to this. For example, as shown in FIG5, the inertia member 72 may be engaged by friction with the support member 71, while making direct contact therewith. According to this configuration, it is possible to omit installation of the friction materials.  In the aforementioned preferred embodiment, the inertia member 72 interposes the support member 71 therein. However, the interposing configuration between the inertia member 72 and the support member 71 is not limited to this. For example, as shown in FIG6, the support member 71 may interpose the inertia member 72 therein. In this case, for instance, the support member 71 includes the attachment hub 71a and a clamp portion 71c. The attachment hub 71a is attached to the transmission shaft 6. The clamp portion 71c is attached to the flange portion 71d of the attachment hub 71a by the at least one rivet 75. The clamp portion 71c interposes and holds the inertia member 72 together with the attachment hub 71a therebetween. According to this configuration, the inertia member 72 can be simplified in structure. Hence, the inertia amount can be easily adjusted, and can be easily increased as well.
schematic diagram
723
elastic portion
72
inertia member
5
drive wheel
6
transmission shaft
75
one rivet
71
support member
['1. A power transmission system comprising: an electric motor; a drive wheel; a transmission shaft transmitting a torque between the electric motor and the drive wheel; and an attenuation mechanism attached to the transmission shaft, wherein the attenuation mechanism includes a support member attached to the transmission shaft, and an inertia member disposed to be rotatable relatively to the transmission shaft, the inertia member being engaged by friction with the support member.', '11. The power transmission system according to claim 9, wherein one of the inertia member and the support member includes an elastic portion as the urging means, the elastic portion pressing the other of the inertia member and the support member while being elastically deformed.']