JPS60213508A - Core of safety tyre - Google Patents

Abstract

PURPOSE:To show no trace of produced rust and in addition, to greatly reduce friction resistance of an annular core against tyre skin so as to prevent deterioration and damage due to the reason of increasing heated tyre, by making said core from synthetic resin having restricted values of tensile strength, compression strength, specific gravity and resilient modulus. CONSTITUTION:Inside a tyre skin 1, the constituent members 2a, 2b, 3a and 3b of a tyre core and built up in sequence to form an annular body. A bolt 4 and a nut 11 are inserted into a radial hole formed in the core, and tightened to join said members. The bead part of a tyre is jammed between a side ring 7 and a resilient ring 5 by the resilient force thereof, thereby maintaining safety driving if the tyre is punctured. The core shall be made of synthetic resin having tensile strength of over 600kg/cm<2>, compression strength of over 800kg/cm<2>, specific gravity of under 1.4, tolerable heated temperature of over 150 deg.C at the time of 18.5kg/cm<2> stress application, and resilient modulus between 250 and 1,000kg/mm.<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety tire core that is fitted inside a tire along the outer peripheral surface of a rim and supports the tire outer skin when the internal pressure of the tire decreases.

In order to ensure operational safety when the internal pressure of the tire decreases due to driving or banking, many safety tires have been proposed that have a tire core fitted inside the tire to support the tire outer skin. . Generally, the tire core is the first
As shown in the front view in Fig. 2 and the A-A sectional view in Fig. 1 in Fig. 2, the tire has an inner circumferential surface that comes into contact with the outer circumferential surface of the rim, and an outer circumferential surface OF that supports the tire outer skin when the tire internal pressure decreases. It is an annular body, and in order to fit it into the rim, a plurality of members 2a are required.
, 2b, 3a, and 3b are interconnected and assembled into an annular body E as shown in the figure. An example in which the core of the annular body assembled in this way is applied to a safety tire is shown in FIG. 3 as a sectional view.

When the internal pressure of a tire decreases due to a puncture or the like, the tire outer skin deforms as shown by the broken line and is held by the outer peripheral surface of the tire core, allowing safe driving to continue. The characteristics required for this type of safety tire core are, of course, that it has enough strength to hold the load transmitted from the tire outer skin, but also that it does not generate noise during normal driving, and that it has high rolling resistance. These characteristics include the fact that the tire does not interfere with the riding comfort, and that there is less friction and wear with the outer skin of the tire when driving when the internal pressure is low.

An object of the present invention is to provide a core for a safety tire that satisfies these various required characteristics.

The present invention is an annular core that is fitted inside a tire along the outer peripheral surface of the rim and supports the tire outer skin when the tire internal pressure decreases, and the core has a tensile strength of 600 kg/ca or more and a compressive strength of 800 kg/c- above, specific gravity 1.4 or less, stress 1
The heating deformation temperature at 8.5 kg/c1 is 150℃ or higher,
A core for a safety tire characterized by using a synthetic resin having an elastic modulus of 250 to 1000 kg/l or more.

In the present invention, the tensile strength of the synthetic resin used for the core is 60
0 kg/c+a or more is required, and the compressive strength is 800 kg/cn+ or more. The core must have sufficient strength to support the load in the event of a tire puncture, and this load is the largest load to be borne in the radial direction of the tire. Therefore, it is necessary that the tensile strength and compressive strength be within the above-mentioned ranges in order to ensure safe driving in the event of a puncture. Next, if the specific gravity of the material used for the core is high, the weight of the tire will increase, the load on the suspension will increase, and the running resistance will increase, which is undesirable from the viewpoint of fuel efficiency. Therefore, the specific gravity of the core is 1.4 or less, preferably 1.2 or less. The core of the present invention is made of synthetic resin such as polyethylene, polypropylene, nylon, polyester, etc. However, as a general characteristic of synthetic resin, it has the disadvantage of softening due to heat. When a tire banks, the tire outer skin continues to run while being supported by the outer peripheral surface of the core, but at this time friction occurs between the inner surface of the tire outer skin and the outer peripheral surface of the core, heat is accumulated, Temperature rises. For example, a tire with a size of 13/80R20 is mounted on a 8.50Vx20 rim, and monomer casting nylon is used as the core material. 4000kg
When a drum with a diameter of 1707 mm was run for 1 hour at a speed of 3 Qkm/h, it was observed that the temperature of the outer peripheral surface of the core reached 160°C. Therefore, although this final temperature varies somewhat depending on running conditions, core material, and shape, the core material must have a heating deformation temperature of at least 150° C. under a stress of 18.5 kg/cJ.

The core of the present invention is a combination of several constituent members that can be divided in the circumferential direction and is fitted onto the outer peripheral surface of the rim.
The components are usually connected by tightening bolts and nuts. Then, while fitting the core into the rim,
After a tire skin is installed, it is generally difficult to check the mutual bonding state of the constituent members over time unless the tire skin is removed from the rim, and it is difficult to maintain a reliable bonding state throughout the entire life of the tire. is important.

However, the bolts and nuts often become loose due to vibrations and shocks when the tires are running.

Therefore, the present invention improves the elastic modulus of the core material from 250 to 1000.
kg/mm2, and the elastic modulus is 1000
When kir/fin 2 is exceeded, the core material is less deformed by tightening bolts and nuts, and the tightening effect is reduced. On the other hand, if the elastic modulus is less than 250 kg/m2, the above-mentioned values of tensile strength and compressive strength will not be satisfied.

As mentioned above, the core of the present invention is made of synthetic resin, but as a general characteristic of synthetic resin, it has a lower coefficient of friction against the tire outer skin than metal used for the core material. This has the advantage of reducing temperature rise.

Conventional safety tire cores are made of metal, such as aluminum, but they have high frictional resistance with the tire outer skin.
Since the temperature rises rapidly and makes long-term safe driving difficult, attempts have been made to apply lubricant to the outer circumferential surface of the core or the inner circumferential surface of the tire outer skin to reduce the frictional resistance mentioned above. , lubricants may cause the rubber of the tire outer skin to swell and deteriorate.
This was causing negative effects such as rust on the rim or metal core.

In the present invention, since a synthetic resin is used, the frictional resistance between the tire outer skin and the core can be effectively reduced without using a lubricant that is used in conjunction with conventional metal cores.

Next, a method for assembling the core of the present invention into a safety tire will be explained with reference to the drawings.

In the figure, in order to assemble a safety tire, constituent members 2a, 2b, 3a, and 3b of a tire core are sequentially assembled inside a tire outer skin 1 to form an annular body. This annular body is provided with radial holes for connecting the structural members to each other, and bolts 4 and nuts 11 are inserted into these holes and tightened to securely connect the structural members. Next, in the gap formed by the outer circumferential surface of the rim and the inner circumferential surface of the core, an elastic ring 5, which has the function of fixing the bead portion that will eventually be located and fixing the core, is installed around the inner circumferential surface of the core. placed on the surface. A rim is inserted inside the combination of the tire outer skin, core, and elastic ring obtained as described above. At this time, one bead of the tire outer skin is placed on one flange side of the rim, and , the rim base 6a is arranged so as to be in contact with the inner circumferential surface of the elastic ring 5. (Fit the barley seal ring 9 and side ring 7. Next, fit the lock ring 8 into the lock groove 10 while inserting the side ring 7 inside the rim in the axial direction. Here, the lock ring 8 has both ends free. It is a metal ring with an adjustable outer diameter at the end.

The bead portion of the tire is fixed between the side ring 7 by the elasticity of the elastic ring 5, and safe driving can be continued even when the tire is punctured.

As an example of the present invention, a core having the following characteristics was manufactured, and when it was assembled into a safety tire as described above and heated, the final temperature of the outer peripheral surface of the core was 130°C. The running conditions were a load of 4000, a speed of 30 km/h, and running on the drum for 1 hour.

Tire core material Monomer casting tensile strength
800 kg/c+J Compressive strength 900 kg/cJ Specific gravity 1.17 Heating deformation temperature 160°C (at stress 18.5 kg/cIa) Elastic modulus 300 kg/in As described above, the core of the present invention is lightweight because it is made of synthetic resin. Moreover, there is no problem of rust compared to conventional metal products.

Furthermore, since the frictional resistance with the tire outer skin can be significantly reduced, there is no problem of deterioration or damage to the tire outer skin due to heat generation and temperature rise.
Furthermore, since materials with specific physical properties are used, the bolts and nuts are highly effective in tightening, and safety is ensured by preventing loosening of the connections between the component parts.

[Brief explanation of the drawing]

Figure 1 is a front view of a conventional core, Figure 2 is A-A in Figure 1.
3 is a sectional view of the safety tire, FIG. 4 is a sectional view of the safety tire, FIG. 5 is a front view of the core of the present invention, and FIG. 6 is a sectional view taken along line B-B in FIG. be. 1--Tire outer skin, 2a, 2b, 3a, 3b-structural members, 4--Nut, 5--Elastic ring, 6--Rim,
7- Side ring, 8- Loft ring, 9- Seal ring, 10- Lock groove. Patent agent Sumitomo Rubber Industries Co., Ltd. Agent Patent attorney Nae Muramasa Figure 4 1 3b 2a 2b Ja

Claims (1)

[Claims] (11 It is an annular core that is fitted inside the tire along the outer peripheral surface of the rim and supports the tire outer skin when the tire internal pressure decreases, and the core has a tensile strength of 600 kg/cJ or more and a compressive strength of 800 kg/- or more. , specific gravity 1.4 or less, stress 18.5
kg/ (Heating deformation temperature at J! is 150'C or more,
A core for a safety tire characterized by using a synthetic resin having an elastic modulus of 250 to 1000 kg/m2 or more.