Studless tires

Abstract

To provide a stud tire which is configured so that friction of an inner bottom surface of a pin hole can be reduced, although running-through performance and braking performance are maintained for a period as long as possible.SOLUTION: A stud tire 50 comprises: a tire 10 having a plurality of pin holes 12; and a plurality of stud pins 20 which are mounted on the pin holes 12, and whose tip parts protrude from the pin holes 12. The stud pins 20 have pedestals 23 protruding laterally. The pin holes 12 have concave parts 13 engaging with the pedestals 23. The stud tire 50 has non-foamy bodies 40 which are lower in hardness than portions 12s constituting the inner bottom surfaces in the tire 10, between base end surfaces of the stud pins 20 and inner bottom surfaces of the pin holes 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a stud tire for a vehicle to travel on a snowy road or the like.

Background Art

[0002] Many stud tires have a tire having a plurality of pin holes and stud pins attached to the respective pin holes with tip portions protruding from the pin holes (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to a stud tire, when traveling on a snowy road, the tip portion of a stud pin pierces the snow surface, thereby preventing slip of the tire with respect to the snow surface. However, during traveling, the stud pin swings within the pin hole, and the base end surface of the stud pin rubs against the inner bottom surface of the pin hole, so that the inner bottom surface of the pin hole may be worn. Further, it is desirable that the tread wear resistance and braking performance of the stud tire be maintained without being reduced for as long a period as possible.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to reduce wear of the inner bottom surface of a pin hole while maintaining the tread wear resistance and braking performance of a stud tire for as long a period as possible.

Means for Solving the Problems

[0006] The inventors of the present invention have discovered that the above objective can be achieved by providing a non-foamed material with a lower hardness than the inner bottom surface of the pin hole between the base end surface of the stud pin and the inner bottom surface of the pin hole, and have arrived at the present invention. The present invention is a stud tire as described in (1) to (3) below.

[0007] (1) A stud tire having a plurality of pin holes and a plurality of stud pins attached to the pin holes and having their tips protruding from the pin holes, The aforementioned stud pin has a base that protrudes laterally, The aforementioned pin hole has a recess that engages with the base, A stud tire having a non-foamed material with a lower hardness than the portion constituting the inner bottom surface of the tire between the base end surface of the stud pin and the inner bottom surface of the pin hole.

[0008] (2) The outer diameter of the base end, which is the end of the base on the side of the stud pin, is smaller than the outer diameter of the base tip, which is the end of the base on the side of the stud pin. The aforementioned non-foamed material has a cylindrical shape. The stud tire according to (1), wherein the outer diameter of the non-foamed material is greater than the outer diameter of the base end and smaller than the outer diameter of the tip of the base.

[0009] (3) The stud tire according to (1) or (2), wherein the hardness of the non-foam material is 15 points or more lower than the hardness of the portion that constitutes the bottom surface of the pin hole in the tire. [Effects of the Invention]

[0010] According to the present invention, the non-foamed material is worn away, weakening the engagement between the base and the recess, causing the stud pin to come out of the pin hole. This makes it possible to reduce wear on the inner bottom surface of the pin hole while maintaining the traction and braking performance of the stud tire for as long as possible. [Brief explanation of the drawing]

[0011] [Figure 1]This is an exploded side cross-sectional view showing a portion of a stud tire according to the first embodiment. [Figure 2] This is a side cross-sectional view showing a portion of a stud tire. [Figure 3] This is a side cross-sectional view showing a stud tire with the non-foamed material worn away. [Figure 4] This is a side cross-sectional view showing a studded tire with a stud pin that has fallen out. [Figure 5] This is a side cross-sectional view showing an example of a modified studless tire. [Figure 6] This is a plan view of a stud pin, seen from the tip side. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited in any way to the following embodiments and can be implemented with appropriate modifications without departing from the spirit of the invention.

[0013] [First Embodiment] Figure 1 is an exploded side cross-sectional view showing a portion of the stud tire 50 of the first embodiment. The stud tire 50 has a tire 10 that is attached to a vehicle, a plurality of stud pins 20 attached to the tire 10, and non-foamed rubber 40 provided for each stud pin 20. Hereinafter, the radial direction of the tire 10 will be referred to as the "tire radial direction".

[0014] The tire 10 has a base layer 10b and a cap layer 10a in its tread. The cap layer 10a is located radially outward from the base layer 10b and has higher durability and hardness than the base layer 10b.

[0015] The cap layer 10a has pin holes 12 for embedding stud pins 20. The pin holes 12 extend inward in the tire radial direction from the tread surface, which is the outer circumferential surface of the cap layer 10a. The pin holes 12 have a recess 13 at the bottom that protrudes laterally.

[0016] Hereinafter, the tip side of the stud pin 20 is referred to as the "pin tip side", and the base end side of the stud pin 20 is referred to as the "pin base end side". The number of stud pins 20 may be appropriately set to any number, for example, 50 or more, 100 or more, 150 or more, etc., according to the required tread wear resistance, braking performance, etc. of the stud tire 50.

[0017] Each stud pin 20 has a bottomed cylindrical shank 20b that opens to the pin tip side, and a cylindrical tip 20a that is inserted into the shank 20b and whose tip protrudes from the shank 20b. The shank 20b is made of, for example, aluminum, and the tip 20a is made of, for example, tungsten.

[0018] The shank 20b has a large diameter portion 21, a small diameter portion 22, and a pedestal 23 in order from the tip side. The outer diameter φ1 of the large diameter portion 21 is larger than the outer diameter φ2 of the small diameter portion 22.

[0019] The pedestal 23 has a tapered shape that tapers as it progresses from the pin tip side to the pin base end side. Therefore, the outer diameter φ3b of the pedestal base end portion 23b, which is the end portion of the pedestal 23 on the pin base end side, is smaller than the outer diameter φ3a of the pedestal tip portion 23a, which is the end portion of the pedestal 23 on the pin tip side. The outer diameter φ3a of the pedestal tip portion 23a is larger than the outer diameter φ1 of the large diameter portion 21.

[0020] The non-foamed rubber 40 is a non-foamed rubber that is not a foam, and has a cylindrical shape. The outer diameter φ4 of the non-foamed rubber 40 is larger than the outer diameter φ3b of the pedestal base end portion 23b and smaller than the outer diameter φ3a of the pedestal tip portion 23a. The non-foamed rubber 40 is adhered to the base end surface of the stud pin 20 with an adhesive or the like in the state of a new stud tire 50.

[0021] Hereinafter, the portion of the cap layer 10a that constitutes the inner bottom surface of the pinhole 12 will be referred to as the "pinhole inner bottom 12s". The hardness of the non-foamed rubber 40 is approximately 30 to 45 points, and the hardness of the cap layer 10a including the pinhole inner bottom 12s is approximately 50 to 60 points. Therefore, the hardness of the non-foamed rubber 40 is lower than the hardness of the pinhole inner bottom 12s. Specifically, the hardness of the non-foamed rubber 40 is preferably 15 points or more lower than the hardness of the pinhole inner bottom 12s, and more preferably 20 points or more lower. Note that the hardness referred to in this embodiment is the hardness measured using the rubber measurement method of durometer type A of JIS 6253.

[0022] When inserting the stud pin 20 and non-foamed rubber 40 into the pin hole 12, the outer edge of the base tip 23a pushes the pin hole 12 radially outward while the stud pin 20 is pushed into the pin hole 12. When the base 23 engages with the recess 13, the installation is complete.

[0023] Hereinafter, the length from the inner wall surface on the outer side in the tire radial direction to the inner wall surface on the inner side in the tire radial direction in the recess 13 will be referred to as the "recess thickness T1". Also, the length from the end face of the base 23 opposite to the non-foamed rubber 40 side to the end face of the non-foamed rubber 40 opposite to the base 23 side will be referred to as the "protrusion thickness T2".

[0024] Figure 2 is a side cross-sectional view showing the stud pin 20 attached to the tire 10. The tip 20a protrudes radially outward from the pin hole 12. In other words, the tip of the stud pin 20 protrudes radially outward from the tread surface 10s of the tire 10.

[0025] The thickness T2 of the protruding portion is approximately the same as or greater than the thickness T1 of the recessed portion when the stud tire 50 is new. During driving, the non-foamed rubber 40 is gradually worn away as the stud pin 20 vibrates within the pin hole 12. As a result, the thickness T2 of the protruding portion gradually decreases.

[0026] Specifically, first, the runout causes the adhesive between the stud pin 20 and the non-foamed rubber 40 to break. Subsequently, further runout causes friction between the base end surface of the stud pin 20 and the non-foamed rubber 40, gradually wearing away the non-foamed rubber 40 from the stud pin 20 side. As a result, the thickness T2 of the protrusion gradually decreases, as described above.

[0027] Figure 3 is a side cross-sectional view showing the non-foamed rubber 40 after some wear. Note that in Figure 3, the wear of the non-foamed rubber 40, i.e., the decrease in the thickness T2 of the protrusion, is exaggerated for the sake of visibility. As the thickness T2 of the protrusion becomes smaller than the thickness T1 of the recess, the engagement between the base 23 and the recess 13 weakens, and the stud pin 20 falls out of the pin hole 12.

[0028] Figure 4 is a side cross-sectional view showing the state in which the stud pin 20 has fallen out of the tire 10. The area where the stud pin 20 has fallen out is in the same condition as a normal tire.

[0029] The effects of this embodiment are summarized below. When the stud pin 20 vibrates within the pin hole 12 while the vehicle is in motion, the non-foamed rubber 40 has a lower hardness than the bottom 12s of the pin hole, so the non-foamed rubber wears down preferentially. As a result, the bottom 12s of the pin hole is protected. When the non-foamed rubber 40 is worn away, the engagement between the base 23 and the recess 13 weakens, and the stud pin 20 comes out of the pin hole 12. Therefore, even if the non-foamed rubber 40 is worn away, the stud pin 20 remains in the pin hole 12, which prevents damage to the bottom 12s of the pin hole due to friction with the base end surface of the stud pin 20.

[0030] While the traction and braking performance of the stud tire 50 will decrease by the amount of stud pins 20 that have come loose, this is not a dramatic reduction as it is only one pin out of dozens or hundreds of stud pins 20. Therefore, the benefit of preventing damage to the bottom 12s of the pin hole outweighs the disadvantage of this reduction. Drivers should consider replacing the stud tire 50 or using it as a normal tire once a certain number of stud pins 20 have come loose.

[0031] Furthermore, non-foamed rubber 40 is more resistant to repeated strain than foam. Therefore, it can suppress problems such as the rubber weakening due to repeated strain and the stud pins 20 coming loose even though they are not worn down much. As a result, as long as there is sufficient non-foamed rubber 40 remaining, the stud pins 20 can be retained in the tire 10 for as long as possible, and the traction and braking performance of the stud tire 50 can be maintained for as long as possible.

[0032] Furthermore, since the outer diameter φ4 of the non-foamed rubber 40 is larger than the outer diameter φ3b of the base end portion 23b, it is possible to more reliably prevent the outer edge of the base end portion 23b from contacting the inner bottom surface of the pin hole 12.

[0033] Furthermore, since the outer diameter φ4 of the non-foamed rubber is smaller than the outer diameter φ3a ​​of the base tip 23a, the problem of the outer edge of the non-foamed rubber 40 hindering the engagement between the base tip 23a and the recess 13 can be suppressed. As a result, as long as there is sufficient thickness remaining in the non-foamed rubber 40, the stud pin 20 is more easily held firmly in the pin hole 12, making it easier to achieve the above configuration, namely, the configuration in which the engagement between the base 23 and the recess 13 weakens as the non-foamed rubber 40 is worn away, causing the stud pin 20 to come out of the pin hole 12.

[0034] Furthermore, when driving in the pins, the base tip 23a, which is less prone to deformation than the non-foamed rubber 40, can be held by a machine or the like. This makes it easier to ensure the accuracy of the pin driving. Moreover, when driving in the pins, the outer edge of the base tip 23a, which is less prone to deformation, can push the pin hole 12 radially outward while simultaneously pushing the stud pin 20 into the pin hole 12.

[0035] [Other embodiments] The above embodiments can be modified as follows, for example. If the shape of the tip 20a is other than a substantially cylindrical shape, the shape of the tip 20a may be other than a substantially cylindrical shape, for example. Specifically, as in the modified examples shown in Figures 5 and 6, the shape of the tip 20a may be a pentagon in a plan view seen from the pin tip side. [Explanation of Symbols]

[0036] 10 tires 12 pin holes 12s pin hole inner bottom 13 recess 20 stud pins 23 Pedestal 23a Tip of the base 23b Base of the pedestal 40 Non-foamed rubber 50 Studless tires φ3a Outer diameter of the tip of the base φ3b Outer diameter of the base end φ4 Outer diameter of non-foamed rubber

Claims

1. A stud tire having a tire with multiple pin holes and a plurality of stud pins attached to the pin holes, the tips of which protrude from the pin holes, The aforementioned stud pin has a base that protrudes laterally, The aforementioned pin hole has a recess that engages with the base, Between the base end face of the stud pin and the inner bottom surface of the pin hole, there is a non-foamed material with a lower hardness than the portion constituting the inner bottom surface of the tire. The outer diameter of the base end, which is the end of the base on the side of the stud pin, is smaller than the outer diameter of the base tip, which is the end of the base on the side of the stud pin. The aforementioned non-foamed material has a cylindrical shape. The outer diameter of the non-foamed material is larger than the outer diameter of the base end and smaller than the outer diameter of the tip end of the base. The non-foamed material is configured to wear away from the stud pin side due to friction with the stud pin as the stud tire is used. The aforementioned pin hole is configured such that as the non-foam material is worn away from the stud pin side, the engagement between the recess and the base weakens, making it easier for the stud pin to fall out. Studless tires.

2. The stud tire according to claim 1, wherein the hardness of the non-foamed material is 15 points or more lower than the hardness of the portion constituting the bottom surface of the pin hole in the tire.

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