JPS61285103A - Low-pressure wide-width tire - Google Patents

Abstract

PURPOSE:To decrease rolling resistance and improve steering performance by providing a center lug having a nearly circular cross section and protruding in the tire diameter direction at a specific value or less of a tire width along the outer periphery near the center of the tire width. CONSTITUTION:A bollon tire 14 is fitted to the halved rim 36 of a front wheel 10 and a rear wheel 12. This tire 14 has a very large tire width (b) against the rim diameter (a) of the rim 36 and is set to a=b or a<b. In this case, a center lug 38 having a nearly circular cross section is integrally formed so as to protrude in the tire diameter direction along the whole tire circumference on the outer periphery of the tire near the center face A. For example, the center D of the arc of the center lug 38 is located on the center face A, and its radius (r) is set sufficiently smaller than a radius R in case the center lug 38 is removed. Accordingly, the travel performance on a hard road can be improved without deteriorating the travel performance on a soft road.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a low-pressure wide tire used for vehicles traveling on rough terrain.

(Background of the Invention) Low-pressure wide tires have been widely used in vehicles for traveling on rough terrain. Balloon tires are known as a type of such low-pressure wide tires. These balloon tires are normally used at an air pressure of about 0.15 to 0.2 kg/cm2 (gauge pressure), and many are made so that their width is about the same as the rim diameter. Furthermore, there have been various types of low-pressure wide tires in which the air pressure is set higher than that of Herun tires but sufficiently lower than that of normal tires, and the tire width is approximately 1/2 of the rim diameter.

This type of low-pressure wide tire has a very large ground contact area, resulting in high rolling resistance. This causes problems in that not only running resistance increases, but also steering becomes heavier. In addition, this type of tire also has a wider width at the contact area. For this reason, when a vehicle equipped with this type of tire tilts its left and right vehicle bodies during a turn, the tire deforms significantly and the center of contact with the ground changes significantly in the width direction of the tire.

FIG. 4 is a sectional view showing the state of deformation of the tire during turning when a conventional balloon tire is mounted on a motorcycle for traveling on rough terrain. In this way, when the vehicle body leans during a turn, the ground contact center B is largely displaced with respect to the tire center plane A, and the amount of displacement C of the ground contact point increases. For this reason, especially when this tire is installed on the front steering wheel, the distance between the center of the steering axis and the ground contact center B where rolling resistance acts becomes large, and the rolling resistance is very large, so the front steering wheel A large rotational force is generated in the direction of increasing the steering angle. As a result, a problem arises in that steering performance during turning deteriorates.

(Object of the Invention) The present invention has been made in view of the above circumstances, and it reduces rolling resistance, and when applied to the steering front wheels, reduces steering force and improves steering performance. The purpose is to provide low-pressure wide tires that can be used.

(Structure of the Invention) According to the present invention, the object is to provide a low-pressure wide tire having a tire width of 1/2 or more of the rim diameter, with a substantially circular cross section protruding in the radial direction of the tire with a width of 273 or less of the tire width. This is achieved by a low-pressure wide tire characterized in that an arc-shaped central protrusion is provided along the outer periphery near the center of the tire width.

(Example) Fig. 1 is a sectional view of a balloon tire sliding wheel according to an embodiment of the present invention, Fig. 2 is a side view of a motorcycle for traveling on rough terrain to which the heavy wheels are applied, and Fig. 3 is a turning FIG.

In FIG. 2, reference numeral 10 indicates a steering front wheel, and 12 indicates a driving rear wheel, on which balloon tires 14, which will be described later, are mounted. Note that the wheel dimensions of the front wheel IO and the rear wheel 12 and the dimensions of each part of the tire 14 may be different between the front wheel IO and the rear wheel 12.

The front wheels 1O are attached to the heavy frame via front forks 16 so as to be steerable left and right. 18 is a steering bar handle.

The rear wheel 12 is held by a rear arm 20 so as to be vertically movable. The rotation of the engine 22 is transmitted via a chain 26 to an intermediate shaft 24 provided on the rear arm 20, and the rotation of the intermediate shaft 24 is further transmitted to the rear wheel 12 via a chain 28. 30 is a shock absorber that supports the rear arm 20, 32 is a fuel tank, and 34 is a straddle-type driver seat.

The front wheel lO and the rear wheel 12 are constructed as shown in FIG. 36 is a two-part rim, and the balloon tire 14
is attached to this rim 36. This tire 14 has a very large tire width relative to the rim diameter a of the rim 36, and is set such that a=b or a<b. On the outer periphery of the tire 14 near the center plane A, a central protrusion 38 having a substantially arcuate cross section is integrally formed over the entire circumference of the tire so as to protrude in the tire radial direction. The center of the circular arc of this central protrusion 38 is located on the central plane A, and the radius r is
The radius R is set to be sufficiently smaller than the radius R (of a normal balloon tire) when 8 is removed. In FIG. 1, E indicates the center of this circular arc of radius H. In this example, the center
E are both located on the tire center plane A.

It is desirable that the width C of the central protrusion 38 is less than or equal to 273 mm of the tire width, and a width of about 1/2 is particularly suitable. The height d of the central protrusion 38 is preferably about 10 to 15% of the tire cross-sectional height e. However, it goes without saying that the shape and dimensions of the central abutment 38 may be changed depending on the usage conditions of the tire, the hardness and thickness of the rubber used, etc. Further, the central protrusion 38 may be formed so as to be continuous with the outer periphery of the tire 14, may be formed in a block pattern, or may have a groove formed therein.

When driving on a hard road surface F (Fig. 1) such as a paved road with the tires 14 configured as described below-1- mounted,
The central protrusion 38 is grounded. Therefore, the ground contact area becomes small and the rolling resistance of the tire 14 becomes very small. Furthermore, when turning, the tires 14 deform as shown in FIG. At this time, since the radius r of the circular arc of the central protrusion 38 is small, the amount of displacement C of the ground contact center B is extremely small. As the rolling resistance decreases and the amount of displacement of the ground contact center B also decreases, the rotational force around the steering axis of the front wheels 10 generated by this rolling resistance also decreases significantly, and the steering performance when turning is improved by -1. - to do.

Furthermore, when driving on a soft road surface G (Fig. 1) such as a sandy area or a swamp, the tire 14 sinks into the road surface G and generates a sufficiently large buoyant force S, resulting in a decrease in performance compared to conventional balloon tires. Not at all.

In the following embodiments, a balloon tire is used in which the tire width is approximately equal to or larger than the rim diameter a, but the present invention applies to any tire whose width is at least 1/2 of the rim diameter a. The desired effect can be obtained.

(Effects of the Invention) As shown in L below, the present invention has a structure in which the outer circumferential surface of the tire has two parts of the width of the tire.
Since the central protrusion is provided with a substantially arcuate cross section having a width of /3 or less, when driving on a hard road surface, this central protrusion mainly contacts the ground, reducing rolling resistance. Also, when turning, the displacement of the center of ground contact is small, improving steering performance. On the other hand, when driving on soft roads, parts other than the central protrusion sink down to provide sufficient buoyancy, so steering performance on soft roads does not deteriorate. As described above, according to the present invention, the running performance on hard roads can be significantly improved without reducing the performance when running on soft roads.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a wheel with a balloon tire that is an embodiment of the present invention, FIG. 2 is a side view of a two-wheeled vehicle that is an example of its application, FIG. 3 is a cross-sectional view showing tire deformation during turning, and FIG. The figure is a cross-sectional view showing tire deformation when a conventional balloon tire turns. 14... Tire, 36... Rim, 38... Central protrusion, a... Rim diameter, b... Tire width.

Claims (1)

[Scope of Claims] A low-pressure wide tire having a tire width of 1/2 or more of the rim diameter, comprising: a central protrusion having a generally arcuate cross section that protrudes in the radial direction of the tire with a width of 2/3 or less of the tire width; , a low-pressure wide tire characterized by being provided along the outer periphery near the center of the tire width.