JP4274466B2 - Pneumatic cushion tire - Google Patents

Description

  The present invention relates to a pneumatic cushion tire having a tire cross-sectional shape and an internal rubber arrangement that can reduce rolling resistance and reduce vehicle power consumption, and is particularly suitable for a pneumatic cushion tire used as a total rubber tire for a battery forklift. It is a thing.

  Conventionally, for example, in a total rubber tire used for a vehicle such as a battery forklift, the rolling resistance is reduced by adopting a rubber material that can reduce loss or reducing the tire weight. The power consumption of the vehicle has been reduced.

On the other hand, by optimizing the cross-sectional shape of the tire, for example, the radius of curvature that forms the surface of the tread, the tread width, and the tire width, the tire life, riding comfort performance, braking performance, and the like are determined. It was. For example, in Patent Document 1, by providing a plurality of lateral grooves having a radius of curvature of a tread surface within a predetermined range and having a predetermined inclination angle and direction, wear resistance is improved and vehicle vibration is reduced. Pneumatic solid tires to be obtained have been reported.
Japanese Patent Laid-Open No. 7-232508

  As demand for total rubber tires for battery forklifts increases, it has recently been demanded to reduce the power consumption of vehicles such as battery forklifts by reducing the rolling resistance of the tires. Therefore, it is necessary to further reduce the rolling resistance of the tire. However, in the conventional total rubber tire, the rolling resistance cannot be sufficiently reduced only by adjusting the rubber quality or reducing the tire weight. It was.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pneumatic cushion tire that can significantly reduce rolling resistance and reduce vehicle power consumption by optimizing the tire cross-sectional shape and internal rubber arrangement. There is.

  As a result of intensive studies to solve the above problems, the present inventor has found that in the case of a pneumatic cushion tire, the portion involved in rolling resistance, that is, the portion where loss occurs is mostly the top rubber layer (the rubber layer near the road surface). Based on the knowledge that it is effective to reduce the strain area and the amount of strain that occurs particularly near the road surface during rolling, in order to reduce the rolling resistance, the tire cross section that minimizes them As a result of further intensive studies on the shape and internal rubber arrangement, the present invention has been completed.

That is, the pneumatic cushion tire of the present invention includes a base rubber layer mounted on a normal rim, an intermediate rubber layer sequentially disposed on the outer side in the tire radial direction of the base rubber layer, and a top rubber layer. In a pneumatic cushion tire having three rubber layers,
The radius of curvature that forms the surface of the tread is CR, the tire diameter is OD, the maximum tire width is Max.OW, the tread width is TW, the regular rim width is RW, and the height of the tire maximum width position from the bead baseline is Max. When OW Ht and tire radial cross-section height from the bead baseline are Ht, respectively,
0.4 ≦ CR / OD ≦ 0.55 (1)
1.1 ≦ Max.OW / TW ≦ 1.25 (2)
1.2 ≦ Max.OW / RW ≦ 1.7 (3)
1.0 ≦ TW / RW ≦ 1.4 (4)
0.65 ≦ Max.OW Ht / Ht ≦ 0.75 (5)
It is characterized by satisfying the relationship represented by

In the pneumatic cushion tire of the present invention, when the tire radial cross-sectional height from the bead base line of the intermediate rubber layer is Gtm Ht,
0.65 ≦ Gtm Ht / Ht ≦ 0.75 (6)
Max.OW Ht ≧ Gtm Ht (7)
The top rubber layer loss (Tan δ) and the modulus M ₁₀₀ at 100% elongation are respectively expressed by the following equations:
Tanδ ≦ 0.2 (8)
M ₁₀₀ ≧ 2.5 (MPa) (9)
It is preferable to satisfy the relationship represented by these.

  In the present invention, the base rubber layer is preferably a fiber cord reinforced rubber layer reinforced with a short fiber cord.

  According to the present invention, it is possible to significantly reduce the rolling resistance as compared with the past and to reduce the power consumption of the vehicle.

  A pneumatic cushion tire according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a meridional sectional view (left half) including a tire shaft when a pneumatic cushion tire (hereinafter referred to as “cushion tire”) 1 according to an embodiment of the present invention is mounted on a regular rim. It is.

  In FIG. 1, the cushion tire 1 includes a base rubber layer 2 mounted on a regular rim 5, an intermediate rubber layer 3 sequentially disposed on the outer side in the tire radial direction, and a top rubber layer 4.

  The outer peripheral surface of the cushion tire 1 shown in FIG. 1 is a tread 6 that becomes a tread surface portion in contact with the road surface. The surface of the tread 6 is formed in a crown shape that is an arc shape. The radius of curvature CR, the tire diameter OD, the cushion tire, the maximum width Max.OW, the tread width TW, and the cushion tire that form the crown shape of the tread 6 The normal rim width RW which is the width of the normal rim 6 to which 10 is attached, the height Max.OW Ht of the tire maximum width position from the bead base line B, and the tire radial section height Ht from the bead base line B are respectively The relationship of the following formulas (1) to (5) is satisfied.

0.4 ≦ CR / OD ≦ 0.55 (1)
1.1 ≦ Max.OW / TW ≦ 1.25 (2)
1.2 ≦ Max.OW / RW ≦ 1.7 (3)
1.0 ≦ TW / RW ≦ 1.4 (4)
0.65 ≦ Max.OW Ht / Ht ≦ 0.75 (5)

  If the value of CR / OD is small, that is, if the radius of curvature CR that forms the surface of the tread 6 is small, the length in the width direction of the grounding surface is reduced. It increases and the rolling resistance tends to deteriorate. From this viewpoint, it is possible to reduce the ground contact area and the deformation region by setting the radius of curvature CR so as to satisfy the above expression (1).

  In order to reduce the strain area and the amount of strain generated near the road surface of the cushion tire 1 during rolling, it is necessary to increase the volume of the rubber, but simply increasing the volume of the rubber also increases the weight. As a result, the rolling resistance cannot be reduced. However, it is effective to increase the rubber volume of the top rubber layer 2 (in the vicinity of the road surface) that generates a lot of loss during rolling. In this case, the portion of the top rubber layer 2 where the volume of the rubber is increased is about 70% of the tire radial cross-section height Ht, and the weight near the road surface in the top rubber layer 2 is not increased unnecessarily. It can be lowered effectively. From this viewpoint, the amount of strain in the vicinity of the road surface of the top rubber layer 2 can be suppressed by setting the tire maximum width (Max.OW) so as to satisfy the expressions (2) to (4).

In the present invention, the tire radial cross-sectional height Gtm Ht from the bead base line B of the intermediate rubber layer 3, the tire radial cross-sectional height Ht from the bead base line B, and the tire maximum from the bead base line B The height Max.OW Ht of the significant position is
0.65 ≦ Gtm Ht / Ht ≦ 0.75 (6)
Max.OW Ht ≧ Gtm Ht (7)
And the loss (Tanδ) of the top rubber layer 4 and the modulus M ₁₀₀ at 100% elongation are respectively expressed by the following equations:
Tanδ ≦ 0.2 (8)
M ₁₀₀ ≧ 2.5 (MPa) (9)
It is preferable to satisfy the relationship represented by these. By providing the top rubber layer 4 so as to satisfy the formulas (6) and (7) and applying a low-loss rubber layer satisfying the formulas (8) and (9) to the top rubber layer 4, the rolling resistance can be further reduced. Is obtained.

  Note that the tire radial cross-sectional height Gmb Ht of the base rubber layer 2 only needs to be such that the fitting property with the rim can be maintained. If the low-loss rubber is also applied to the rubber of the intermediate rubber layer 3, the rolling resistance is further reduced. Can be planned.

  The intermediate rubber layer 3 is preferably a soft rubber having a JIS-A hardness of about 40 to 65 degrees and excellent cushioning properties, and the top rubber layer 4 is preferably resistant to a JIS-A hardness of about 60 to 75 degrees. Rubber with excellent wear and cut resistance. The compounding system of the rubber composition of the intermediate rubber layer 3 and the top rubber layer 4 is not particularly limited, and a known compounding system used for the same purpose as before can be appropriately selected.

  The base rubber layer 2 is made of fiber reinforced rubber in which an organic fiber cord such as polyamide such as nylon or polyester such as polyethylene terephthalate (PET) is cut short, preferably 20 to 70% mixed with a short fiber cord of 20 to 80 mm. Thus, the hardness of the base rubber layer can be increased.

  In addition, although the tread 6 of the illustrated cushion tire 1 is a smooth tire without a pattern, a groove portion may be appropriately formed.

  Hereinafter, the present invention will be described based on examples.

Conventional example, Examples 1 and 2
Rear tires (size 5.00-8) satisfying the conditions shown in Table 1 below and front tires (size 21 × 8-9) satisfying the conditions shown in Table 2 below were respectively prototyped. All the cushion tires are smooth tires without a pattern. The values of Tan δ in Tables 1 and 2 are values measured using a spectrometer (manufactured by TOYOSEKI Corporation) under the conditions of room temperature, 52 Hz, initial strain of 5%, and amplitude strain of 2%. The value of M ₁₀₀ is a value measured according to JIS K6301.

  These cushion tires were mounted on a 1.5-ton battery forklift, and were run on a 40 m straight course, which is an indoor concrete road, and a mode course shown in FIG. 2 to evaluate power consumption. Note that the battery forklift travels repeatedly along the route indicated by the arrow of the mode course shown in FIG.

  Here, as a test method for evaluating power consumption, the vehicle power mode is set to the standard mode gear, the vehicle is set to the regenerative on state, and the battery forklift is driven at a speed of 15 km / h in the full accelerator mode. The battery power consumption was measured using a clamp meter. The results obtained are shown in Table 3 below. In addition, each power consumption value in Table 3 is displayed as an index when the value of the conventional example is set to 100. The smaller the value, the better the result and the lower the fuel consumption.

  From the test results shown in Table 3, compared to the conventional cushion tire, the cushion tire of Example 1 according to the present invention clearly has reduced power consumption, and further preferred rubber quality of the top rubber layer. It can be seen that the power consumption of the cushion tire is significantly reduced.

It is a fragmentary sectional view of the cushion tire concerning one embodiment of the present invention. It is explanatory drawing which shows the route of a mode course.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cushion tire 2 Base rubber layer 3 Intermediate rubber layer 4 Top rubber layer 5 Regular rim 6 Tread

Claims (3)

In a pneumatic cushion tire having three types of rubber layers: a base rubber layer attached to a regular rim, an intermediate rubber layer sequentially disposed on the outer side in the tire radial direction of the base rubber layer, and a top rubber layer ,
The radius of curvature that forms the surface of the tread is CR, the tire diameter is OD, the maximum tire width is Max.OW, the tread width is TW, the regular rim width is RW, and the height of the tire maximum width position from the bead baseline is Max. When OW Ht and tire radial cross-section height from the bead baseline are Ht, respectively,
0.4 ≦ CR / OD ≦ 0.55 (1)
1.1 ≦ Max.OW / TW ≦ 1.25 (2)
1.2 ≦ Max.OW / RW ≦ 1.7 (3)
1.0 ≦ TW / RW ≦ 1.4 (4)
0.65 ≦ Max.OW Ht / Ht ≦ 0.75 (5)
A pneumatic cushion tire characterized by satisfying the relationship expressed by When the tire radial cross-section height from the bead base line of the intermediate rubber layer is Gtm Ht,
0.65 ≦ Gtm Ht / Ht ≦ 0.75 (6)
Max.OW Ht ≧ Gtm Ht (7)
The top rubber layer loss (Tan δ) and the modulus M ₁₀₀ at 100% elongation are respectively expressed by the following equations:
Tanδ ≦ 0.2 (8)
M ₁₀₀ ≧ 2.5 (MPa) (9)
The pneumatic cushion tire according to claim 1, which satisfies a relationship represented by:   The pneumatic cushion tire according to claim 1 or 2, wherein the base rubber layer is a fiber cord reinforced rubber layer reinforced with a short fiber cord.

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