TECHNICAL FIELD

The present invention relates to a non-pneumatic tire including a tread part, a wheel part, and a spoke part.

BACKGROUND ART

A general tire is attached to a wheel and filled with air (hereinafter this tire is referred to as a “pneumatic tire (air tire)”). On the other hand, particularly a micro electric vehicle (MEV) has come to employ a non-pneumatic tire (airless tire) that can be used without being filled with air. In this case, the non-pneumatic tire is advantageous because daily check of the tire pressure is unnecessary and the non-pneumatic tire is free of risk of a tire puncture.

In a vehicle including non-pneumatic tires, in order to mitigate the sense of discomfort experienced by a user (driver or passenger), it is desirable that the user can feel comfortable and steer stably in a manner similar to a vehicle including the pneumatic tires. Therefore, the non-pneumatic tire is required to exhibit the characteristics equivalent to those of the pneumatic tire. From such a perspective, Japanese Laid-Open Patent Publication No. 2016-041573, Japanese Laid-Open Patent Publication No. 2014-118128, and International Publication No. WO 2014/188912 have made various suggestions.

SUMMARY OF INVENTION

As described in Japanese Laid-Open Patent Publication No. 2016-041573, Japanese Laid-Open Patent Publication No. 2014-118128, and International Publication No. WO 2014/188912, it has conventionally been attempted to improve the characteristics of the non-pneumatic tire by setting the structure, the shape, and the material of a tread part or a spoke part; however, further improvement of the characteristics of the non-pneumatic tire has been required.

It is a main object of the present invention to provide a non-pneumatic tire having excellent responsiveness at the time a vehicle makes a turn while traveling.

A non-pneumatic tire according to one embodiment of the present invention includes a tread part with a cylindrical shape that is in contact with a ground surface, a wheel part disposed inside the tread part in a radial direction, and a spoke part interposed between the tread part and the wheel part, wherein: the wheel part includes a disk part to which an axle is connected, and a rim part whose inner circumferential side is continuously connected to the disk part and outer circumferential side is joined to the spoke part; and an average thickness of the disk part is larger than an average thickness of the rim part.

In this case, the disk part is bent less easily. Therefore, when the vehicle makes a turn (corners), the responsiveness is excellent from a low-speed range to a high-speed range. Thus, a user can experience what is called sport driving and feel as if in a sport car. In addition, in the low-speed range, the transient characteristic similar to that of a pneumatic tire can be obtained; therefore, a sense of discomfort experienced by the user is mitigated.

Note that it is preferable that the spoke part includes an internal ring part to which the rim part is joined, an external ring part for which the tread part is provided, and a plurality of spokes that integrally connect the internal ring part and the external ring part. Since the spokes provide the elastic operation, external force in the travel is relieved. In addition, it becomes easier to join the wheel part or provide the tread part.

In the wheel part, the disk part and the rim part may be provided as separate members and joined to each other. In this case, the shape of the disk part can be changed variously and the thickness and the height of the rim part can be individually changed variously. Thus, the collapse (or tilting) rigidity of the disk part and/or the flexural rigidity of the rim part in the radial direction thereof can be set easily.

The wheel part may be formed by a single member that integrally includes the disk part and the rim part. In this case, the joining work is unnecessary. Moreover, for example, in a case of manufacturing the wheel part from an aluminum alloy expanded material, the weight can be reduced.

According to the present invention, the average thickness of the disk part included in the wheel part is set to be larger than the average thickness of the rim part that is similarly included in the wheel part. Therefore, the disk part is bent less easily and the members of the wheel part are mainly made of metal; thus, the change in spring constant due to the increase in rotation speed hardly occurs. Accordingly, at the turning (cornering), the transient characteristic similar to that of the pneumatic tire can be obtained in the low-speed range, and the responsiveness is excellent in the high-speed range. Thus, the user can feel as if in sport driving.

