JP5745280B2 - tire - Google Patents

Description

  The present invention relates to a tire used for both traveling on a road and traveling on a rail of a track. In particular, the present invention relates to a tire capable of improving wear resistance and reducing noise during road travel while maintaining traction performance during track travel.

  In recent years, a vehicle (DMV: Dual Mode Vehicle) capable of traveling on both roads and tracks has been proposed. Road transportation has the advantage that it can be transported to any destination as long as there is a road. On the other hand, rail transport has the advantage that it is less susceptible to traffic jams and can be transported as planned. For this reason, this dual-purpose traveling vehicle (hereinafter also referred to as “DMV”) is expected to be able to enjoy the advantages of both road transport and rail transport, and in particular, to effectively utilize the track that has been abolished.

  A tread portion of a tire attached to the DMV (hereinafter also referred to as “DMV tire”) is in contact with the road surface when driving on the road to apply driving force to the DMV, and is contacted with the rail when traveling on track to apply driving force to the DMV To give. Therefore, the tread portion of the DMV tire is required to have characteristics suitable for both travels, and it is considered that characteristics different from those for a normal vehicle tire traveling only on a road are required.

  In Patent Document 1, as a tire used for both traveling on a road and traveling on a rail of a track, a tread pattern based on a block in which a tread portion is formed by a plurality of circumferential grooves and width grooves is formed. Is disclosed. In this document, of the plurality of circumferential grooves, two circumferential grooves formed on both outer sides of the contact area with the rail are formed wider than the other circumferential grooves.

JP 2006-321435 A

  The contact resistance between the DMV tire and the rail is smaller than the contact resistance between the tire and the road. Therefore, when the tread portion is a rib pattern as in a general summer tire, sufficient traction cannot be obtained in the rail contact area of the tread portion during track running, and there is a possibility that slipping may occur in some cases. is there. In this regard, in the DMV tire of Patent Document 1, the entire tread portion is a block pattern, and the rail contact area of the tread portion is naturally also a block pattern, so that higher traction performance than in the case of the rib pattern can be obtained. Can do.

  However, the DMV tire of Patent Document 1 has a problem that since the tread portion has lower rigidity than when the tread portion is a rib pattern, the tread portion is easily worn during road travel. In addition, DMV is a transportation system for the purpose of transporting passengers, and it is also required to have low noise when traveling in urban areas, but tires with block patterns in the tread will emit more noise than in the case of rib patterns. There is also a problem.

  In view of the above problems, an object of the present invention is to provide a DMV tire capable of improving wear resistance and reducing noise during road traveling while maintaining traction performance during track traveling.

  In order to improve wear resistance during road running and to suppress noise, the tread portion of the DMV tire may be a rib pattern. In this case, as described above, sufficient traction is obtained during track running. I can't. In other words, in this case, the performance required when traveling on the track and the performance required when traveling on the road are in a trade-off relationship. Therefore, the present inventor, as a DMV tire, has never made a function separation between road running and track running by changing the tread pattern keynote in the rail contact area and the non-contact area. I got an idea.

  That is, from the viewpoint of maintaining the traction performance during track running, it is sufficient that only the rail contact area is a block pattern, and the rail non-contact area is not necessarily a block pattern. Based on such an idea, the present inventor solves the above-mentioned problem by forming a block-based pattern in the rail contact region and a rib-based pattern in the rail non-contact region in the tread portion of the DMV tire. The present inventors have found that this can be done and have completed the present invention.

That is, in view of the above problems, the gist of the present invention is as follows.
(1) A tire used for both traveling on a road and traveling on a rail of a track,
In the tread part,
A plurality of circumferential grooves extending along the tire circumferential direction are arranged to form a plurality of rows of divided land portions,
Among the plurality of circumferential grooves, a plurality of widthwise grooves extending at least along the tire width direction are spaced apart in the tire circumferential direction on the divided land portions on the inner side in the tire width direction of the predetermined two circumferential grooves. And at least one block land portion row composed of a plurality of block land portions is defined, and the divided land portions on the outer side in the tire width direction of the predetermined two circumferential grooves are rib-shaped land. And
The block land portion row is located at least over the entire rail contact region of the tread portion,
The rib-like land portion is located in a rail non-contact area of the tread portion ,
The surface area of the tread surface of each block land portion constituting the block land portion row where both ends in the tire width direction of the rail contact region are located is the surface area of the tread surface of each block land portion constituting the other block land portion row. Tire characterized by being larger than .

  (2) Among the rib-shaped land portions, the outermost rib-shaped land portion including the tread end in the tire width direction has one end opened at the tread end and the other end terminated in the rib-shaped land portion. The tire according to (1), wherein the widthwise grooves are arranged at intervals in the tire circumferential direction.

(3) The tire according to (1) or (2) , wherein the tread portion has a point-symmetric tread pattern.

(4) The tire according to any one of (1) to (3) , wherein the tire is a summer tire.

(5) The tire according to any one of (1) to (4) , wherein the tire is a heavy duty tire.

  According to the present invention, compared to the case where the entire tread portion is a block pattern, the tread portion is divided into a block land portion row and rib-like land portions on both sides thereof, and the block land portion row extends at least over the entire rail contact region. Positioning allows the traction performance during track running to be maintained, while the rib-like land portion is located in the rail non-contact area, improving wear resistance and reducing noise during road driving. It becomes.

1 is a development view showing a part of a tread portion of a typical tire 100 according to the present invention. It is a figure which shows the cross section of the tire 100 which shows the II cross section in FIG. 1, the cross section of the rail R, and the contact area | region of a tire and a rail. It is an expanded view which shows a part of tread part of another tire 200 according to this invention. FIG. 6 is a development view showing a part of a tread portion of a conventional DMV tire 300. It is a side view which shows the road running state of the vehicle (DMV) with which the tire according to this invention is mounted | worn. It is a side view which shows the track running state of the vehicle (DMV) with which the tire according to this invention is mounted | worn. It is the bottom view which looked at the track running state of Drawing 6 from the rail lower side.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. In principle, the same components are denoted by the same reference numerals, and description thereof is omitted.

(DMV)
Before describing the tire of the present invention, an example of a DMV that is a vehicle to which the tire of the present invention is mounted will be briefly described with reference to FIGS. 5 and 6 are side views of a vehicle (DMV) 700 to which the tire of the present invention is attached. The DMV 700 is configured to be able to travel on both roads and tracks. FIG. 5 shows a state in which the DMV 700 is traveling on the road surface D of the road, and this is referred to as a “road traveling state”. FIG. 6 shows a state in which the DMV 700 is traveling on the rail R of the track, and this is referred to as “track traveling state”.

  The DMV 700 includes a vehicle body 701, a front wheel 702, a rear wheel 703, a front guide wheel 706, and a rear guide wheel 707. A front wheel tire 704 is attached to the wheel rim of the front wheel 702. The rear wheel 703 is a double wheel to support a load during road traveling, and the rear wheel inner tire 100 (the tire of the present invention) and the rear wheel outer tire 705 are mounted on the wheel rim. The rear wheel 703 is a drive wheel driven by the engine, and the front wheel 702 is a driven wheel. The front guide wheel 706 and the rear guide wheel 707 have the same structure as a commonly used railway vehicle wheel, and are made of metal such as steel.

  In the road running state of FIG. 5, the front guide wheel 706 and the rear guide wheel 707 are not used and are housed inside the vehicle body 701. In the road traveling state, the DMV 700 travels when the driving force of the engine is transmitted from the rear wheel 703 to the road surface D.

  On the other hand, in the track running state of FIG. 6, the front guide wheel 706 and the rear guide wheel 707 are used. The front guide wheel 706 and the rear guide wheel 707 are in contact with the rail R in the same manner as a general railway. As a result, the DMV 700 can travel on the rail R without derailing. That is, the front guide wheel 706 and the rear guide wheel 707 serve to guide the DMV 700 on the rail R.

  The rear wheel 703 is in contact with the rail R even in the track running state, and the DMV 700 travels when the driving force of the engine is transmitted to the rail R from the rear wheel 703, more precisely, the inner tire 100 of the rear wheel. To do. On the other hand, the front wheel 702 is separated from the rail R upward and is not in contact with the rail R.

  Thus, the DMV 700 can be easily driven by using the rear wheel 703 as a drive wheel in both the road running state and the track running state. Here, in the track running state, the vertical position of the front guide wheel 706 is set such that the front wheel 702 is separated from the rail R. On the other hand, in the track running state, the position of the rear guide wheel 707 is set so that the rear wheel 703 and the rear guide wheel 707 are in contact with the rail R. As described above, when shifting from the road running state to the track running state, the front guide wheel 706 and the rear guide wheel 707 housed inside the vehicle body 701 are moved downward to contact the rail R, and conversely. When shifting from the track running state to the road running state, the vehicle is moved upward and accommodated in the vehicle body 701. The vertical movement of the front guide wheel 706 and the rear guide wheel 707 may be performed by a hydraulic actuator or the like.

  In the track running state, the rear load of the DMV 700 is shared and supported by the rear wheel 703 and the rear guide wheel 707. When the rear wheel 703 shares the load, a frictional force can be generated between the tire mounted on the rear wheel 703 and the rail R. A driving force is obtained by this frictional force. When the rear guide wheel 707 shares the load, the DMV 701 is prevented from derailing.

  In FIG. 7, the rail R is indicated by a two-dot chain line. In FIG. 7, the configuration of the lower part of the vehicle is omitted except for a part of the axle. In the track running state, the rear wheel inner tire 100 of the rear wheel 703 is in contact with the rail R. When traveling on a straight track, the tire 100 is in contact with the rail R at a substantially center position in the tire width direction. The center distance Tc between the left and right tires 100 is substantially the same as the center distance Rc of the rail R. The distance between the two rails on the track is generally referred to as a gauge. For example, in Japan, there are standard gauges, narrow gauges, wide gauges, and the like. In Japan, standard gauges are used on the Shinkansen and some private railways, and narrow gauge is used on many other routes. The center-to-center distance Tc of the tire 100 that contacts the rail R is designed based on the distance between the tracks on which the DMV 700 travels. If the distance Tc between the centers of the tires is set based on the existing track, the DMV 700 can travel on the existing track.

  Of the tires mounted on the DMV 700, conventional tires for automobiles can be used as the tires 704 and 705 that do not contact the rail R. On the other hand, the tire 100 in contact with the rail R uses the tire of the present invention.

(DMV Tire: Embodiment 1)
Hereinafter, a tire 100 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. The tire 100 is a tire used for both traveling on a road and traveling on a rail of a track, and is used as a driving wheel of the DMV 700. The tread portion 10 of the tire 100 includes block land portion rows 21 to 24 and rib-like land portions 25 and 26 formed on both outer sides in the tire width direction.

  In the tire according to the present invention, a plurality of circumferential grooves extending along the tire circumferential direction are arranged in the tread portion to partition a plurality of rows of divided land portions. In the tire 100 of the present embodiment, five circumferential grooves 11, 12, 13, 14, and 15 extending along the tire circumferential direction C are arranged in the tread portion 10, and between the adjacent circumferential grooves. Four rows of first divided land portions are defined, and one row is formed between each of the tread ends E and the two circumferential grooves 11 and 12 positioned on the outermost side in the tire width direction with the tire equatorial plane CL interposed therebetween. A total of two rows of second divided land portions 25 and 26 are defined.

  And among the circumferential grooves 11 to 15, divided land portions (first divided land portions) 21, 22, 23 inside the tire width direction W of the circumferential grooves 11, 12 which are predetermined two circumferential grooves, 24, a plurality of widthwise grooves 16, 17, 18, and 19 extending along at least the tire width direction W are arranged at intervals in the tire circumferential direction C. Thereby, the 1st division | segmentation land part 21-24 is divided into the block land part row | line | columns 21-24 of at least 1 row (this embodiment multiple row | line | column) which respectively consist of several block land part 31,32,33,34. It is formed. In the present embodiment, the two predetermined circumferential grooves 11 and 12 are circumferential grooves positioned on the outermost side in the tire width direction. Moreover, it is preferable to partition and form a plurality of rows of block land portions as in this embodiment.

  The divided land portions (second divided land portions) 25, 26 on the outer side in the tire width direction W of the predetermined two circumferential grooves 11, 12, that is, on the outer sides in the tire width direction of the block land portion row forming region are rib-shaped land portions. And That is, the second divided land portions 25 and 26 do not have a width direction groove that divides the land portion across the tire width direction.

  The characteristic configuration of the present invention is that the block land portion rows 21, 22, 23, 24 are located at least over the entire rail contact region T of the tread portion 10, and the rib-like land portions 25, 26 are rails of the tread portion 10. The configuration is located in the non-contact area N. The tire 100 generally has a tread width larger than the width Wr of the top surface of the rail R (see FIG. 2), and is in contact with the rail R only within a certain range of the tread portion 10.

  Here, the “rail contact area” in the present specification means an area of the tread portion that can contact the rail R when the tire travels on the track. For example, as shown in FIG. In the tread portion, it can be specified as a region within 100% of the rail width Wr, centering on the width center position of the rail top surface. In this case, the width of the contact region T is equal to the rail width Wr. Further, even on both outer sides of the tire width direction end portion of the rail in the tread portion, as a region having a high frequency of contact with the rail R in normal track traveling such as vehicle turning, for example, the rail top surface in the tread portion of the tire You may specify as an area | region within 150% of rail width centering on a width center position. When the tire equator abuts so that it coincides with the center of the width of the rail top surface, the rail abutment region may be specified as a region within 100% or 150% of the rail width centering on the tire equator. it can. Further, although depending on the rail width of the rail to be used and the tire size, the tire contact area is usually an area of 55% or less of the tread width centering on the tire equator. In the case where the tire is a pneumatic tire, the rail contact region is set based on the state of the tire under a predetermined load condition after the tire is mounted on the applicable rim and filled with a predetermined air pressure.

  In the present specification, the “predetermined air pressure” means an air pressure corresponding to the maximum load (maximum load capacity) of a compound wheel in an applicable size described in the following standard. Further, the “predetermined load condition” means that a load of the maximum load (maximum load capacity) of the compound wheel in the application size described in the standard is applied. The “applied rim” is a standard rim (or “Approved Rim” or “Recommended Rim”) in the applicable size described in the standard. As for such industrial standards, standards that are effective in regions where tires are produced or used are defined. For example, “Year Book of The Tire and Rim Association Inc.” in the United States, “STANDARDS MANUAL of The European Tire and Rim Technical Organization” in Europe, and “JATMA Year Book” of the Japan Automobile Tire Association in Japan. It is.

  In this specification, the “rail non-contact area” means an area other than the rail contact area in the tread portion.

  The rail contact region can be specified by the dimension of the rail R on which the DMV 700 on which the tire 100 is mounted travels, the rail center-to-center distance Rc, and the tire center-to-center distance Tc. Since the center between the tires and the center between the rails coincide, when Rc and Tc are equal, the tire equator CL abuts so as to coincide with the width center of the rail R top surface. However, when the DMV 700 is manufactured by partially modifying an existing vehicle, or when the DMV 700 is driven using an existing track, Rc and Tc cannot always be matched, and the tire equator is somewhat tired. In some cases, the rail R may be offset in the width direction. In any case, when the rail contact area can be specified in advance, the arrangement of the block land portion row and the rib-like land portion may be determined based on this information. Further, the rail contact area may be set so as to be included in the block land portion rows 21 to 24 of the tire 100.

  The type of rail R on which the tire 100 can travel is not limited. As types of the rail R, for example, there are a 30 kg rail, a 37 kg rail, a 40 kg rail, a 50 kg N rail, a 50 kg T rail, a 60 kg rail, and the like. The rail width Wr of the 30 kg rail is 60.33 mm, the rail width Wr of the 37 kg rail is 62.71 mm, the rail width Wr of the 40 kg rail is 64 mm, and the rail width Wr of the 50 kgN rail and the 50 kgT rail is 65 mm. The rail width Wr of the 60 kg rail is 65 mm. In a general railway, the rail width Wr is usually in the range of 60 mm to 65 mm.

  The effect by employ | adopting the said characteristic structure of this invention is demonstrated. The block land portion rows 21, 22, 23, and 24 are located at least over the entire rail contact region T of the tread portion 10. That is, the rail abutment region T is configured as a block pattern as a whole. Here, the block pattern that is a set of block land portions has a stronger action of removing the water film between the rail R and the tread portion 10 than the rib pattern that is a set of rib-like land portions. Therefore, in the present invention, it is possible to sufficiently ensure the traction performance at the time of running on the track as compared with the case where the rail contact region is a rib pattern.

  On the other hand, the rib-like land portions 25 and 26 are located in the rail non-contact area N of the tread portion 10. Thereby, the rigidity of a shoulder part becomes high compared with the case where the side area (shoulder part) of the tread part which is a rail non-contact area | region is a block pattern. Thereby, pattern deformation of a shoulder part is suppressed and abrasion resistance improves. Moreover, the rigidity of the whole tread part is improved by improving the rigidity of the shoulder part, and the load burden on the shoulder part in the ground contact surface is increased. As a result, it is possible to relatively reduce the load on the central region (center portion) of the tread portion and improve the wear resistance of the center portion. Therefore, in this invention, compared with the case where a rail non-contact area | region is a block pattern, the abrasion resistance at the time of road driving | running can be improved as a whole.

  In addition, tire noise is generated when the widthwise grooves hit the road surface during rolling, and the noise source itself can be reduced by making the shoulder portion a rib-like land portion. Therefore, in the present invention, it is possible to reduce noise during road travel as compared with the case where the rail non-contact area is a block pattern.

  As shown in FIG. 1, the block land portion rows 21, 22, 23, and 24 are only required to be positioned at least over the entire rail contact region T, and may be partially included in the rail non-contact region N. . In this case, the tire width direction dimension of the block land portion row that protrudes from the rail contact region T is preferably 5% or less of the tread width. If it exceeds 5%, the traction performance at the time of running on the track does not change, but it becomes difficult to ensure the effect of improving the wear resistance and reducing the noise at the time of running on the road. From the above viewpoint, the tire width direction dimension of the block land portion row protruding from the rail contact region T is more preferably 3% or less of the tread width. In order to ensure the maximum effect of the present invention, both ends of the rib-like land portion 13 (in FIG. 1, the left end of the block land portion row 21 and the right end of the block land portion row 24) are arranged in the rail contact region. Most preferably, it is equal to both ends of T. In addition, when the tire width direction dimension of the block land part row | line | column which protrudes from the rail contact area | region T changes with tire circumferential direction positions like FIG. 1, the above-mentioned should just be satisfy | filled in arbitrary tire circumferential direction positions.

  Further, from the same viewpoint, the block land portion row where both end portions in the tire width direction of the rail contact region T (broken line portions at the boundary between T and N in FIG. 1) are positioned as in the present embodiment. A pair of block land rows 21 and 24 located on the outermost side in the direction is preferable.

  In the tire 100 of the present embodiment, three circumferential grooves 13 to 15 are disposed in the tread portion 10 in addition to the outermost circumferential grooves 11 and 12 that are predetermined two circumferential grooves, and four rows of 1 division land part (block land part row) is divided and formed. Here, since the 2nd block land parts 25 and 26 are rib-like land parts, from the viewpoint of ensuring drainage at the time of road running, arrange three or more circumferential grooves other than the outermost circumferential groove. Is preferred. If the circumferential grooves are provided in excess of six, the rigidity of the tread portion in the rail contact region T is reduced, and the wear resistance during track running is not sufficient.

  The shape of the circumferential grooves 11 to 15 is preferably linear along the tire circumferential direction like the circumferential grooves 15 from the viewpoint of drainage, but the circumferential grooves of the present invention are not limited thereto, Like the circumferential grooves 11 to 14, it may be zigzag to the extent that it does not impair drainage, or it may be wavy with a predetermined wavelength. When three or more circumferential grooves are provided, it is preferable to equalize the circumferential width intervals of these circumferential grooves in order to maintain a rigidity balance in the block land portion region. The groove widths and groove depths of the circumferential grooves are preferably equal to each other in order to maintain a rigidity balance in the block land portion row region.

  In the present embodiment, the circumferential groove 15 is disposed on the tire equator CL, and the circumferential grooves 13 and 14 are positions where the position in the tire width direction of the groove bottom shown in FIG. 2 is 13% of the tread width away from the tire equator CL. Similarly, the circumferential grooves 11 and 12 are located 26% apart, but the present invention is not limited to this. In the present specification, “tread width” means the distance in the tire width direction between the tread ends E.

  In the present embodiment, the two predetermined circumferential grooves 11 and 12 are circumferential grooves positioned on the outermost side in the tire width direction. That is, the second divided land portion becomes a row of rib-shaped land portions on the shoulder portion of the tread portion. However, the present invention is not limited to this, and n circumferential grooves are arranged on both outer sides in the tire width direction of the predetermined two circumferential grooves that divide the first divided land portion and the second divided land portion. And (n + 1) rows of rib-like land portions may be defined in the shoulder portions. However, n is preferably 1 in order to obtain sufficient effects of improving wear resistance and noise reduction during road travel.

  In the block land portions 31 to 34, two width direction open sipes 35 and 36 that completely cross each block in the tire width direction are disposed in the vicinity of the central portion in the circumferential direction of each block. Thereby, the effect | action which removes the water film between the rail R and the tread part 10 can be acquired more fully, and the traction performance at the time of track running can be ensured more fully. The block land portions 31 to 34 are divided into three pseudo block land portions by these two sipes.

In the tire 100, it is preferable that the block average circumferential length Lpc and the tire circumferential direction length Lt at the tire equator CL satisfy the following relationship. In this specification, the “block average circumference” is a value obtained by dividing the tire circumferential length Lt by the number of blocks in the tire circumferential direction (if there is a pseudo-block land portion, this is also regarded as one block). Shall mean.
0.0115 Lpc ≦ Lt ≦ 0.0147 Lpc
The relationship between Lt and Lpc is an index representing the block stiffness balance in the circumferential direction. In the case of Lt <0.0115 Lpc, the block average circumference is short, and sufficient block rigidity cannot be ensured. As a result, there is a possibility that sufficient traction and wear resistance cannot be ensured. In addition, when Lt> 0.0147 Lpc, the wear resistance is improved, but the traction during track running may not be ensured.

  As shown in FIG. 1, it is also preferable to provide circumferential sipes 37 and 38 from the viewpoint of preventing skidding when traveling on roads, particularly on roads on ice and snow.

  In the present invention, the block land portion row only needs to be positioned in the rail contact region T, and the shape, interval, arrangement relationship, and the like of each block land portion are not limited to this embodiment.

  The tread portion 10 preferably has a point-symmetric tread pattern centered on a predetermined point on the tire equator. Accordingly, when the tire 100 is rotated and used for the rear wheel on the opposite side of the DMV 700, it is preferable because wear progresses evenly.

  The tire 100 is preferably a summer tire. The object of the present invention is to improve wear resistance during road running and to reduce noise, and it is assumed that the road surface is used on a normal road surface, not in an icy and snowy state.

  The tire 100 of the present invention can be used with any load, but is preferably a heavy duty tire. This is because the DMV 700 is generally a bus intended for transport of trucks and large numbers of people rather than for passenger cars.

  The tire 100 according to the present invention is characterized in that the tread pattern of the tread portion is changed in the rail contact region T and the rail non-contact region N. Therefore, the tire structure is not limited at all, and a known tire structure is used. be able to.

(Embodiment 2)
A tire 200 according to Embodiment 2 of the present invention will be described with reference to FIG. The tire 200 is different from the tire 100 of the first embodiment only in the configuration of the rib-like land portions 25 and 26, and the other points are the same, so the description thereof is omitted, and only the configuration of the rib-like land portions 25 and 26 is described. To do.

  In the tire 200, a plurality of widthwise grooves (one end is opened in the tread end E and the other end is terminated in the rib-like land portion in the outermost rib-like land portions 24 and 25 including the tread end E in the tire width direction). Lug grooves) 39 and 40 are arranged in the rib-like land portions at intervals in the tire circumferential direction. By providing such width direction grooves 39 and 40 in the rib-like land portions 24 and 25, the traction performance during road traveling is improved. For this reason, the tire 200 is suitable for use in an environment where traction is required, such as an area with a lot of rainfall or an area with a lot of mountain slopes.

  The groove depth of the deepest part of the width direction grooves 39 and 40 is 50% to 85% of the groove depth of the circumferential groove (circumferential groove 15 in this embodiment) on the tire equator CL or closest to the tire equator CL. It is preferable that Further, it is desirable that the distance Lps between the groove width centers of the widthwise grooves adjacent to each other in the tire circumferential direction when measured at the tread edge E and the aforementioned Lpc have a relationship of Lps> Lpc. This is because, when Lps ≦ Lpc, the gap between the lug grooves in the shoulder portion is narrow, and the block rigidity of the shoulder portion cannot be ensured. From the viewpoint of wear resistance, noise, and traction, which are the effects of the present invention, it is preferably in the range of 1.8 Lpc <Lps <2.2 Lps.

(Other embodiments)
Although not shown, the block land portion row in which both ends of the rail contact region T in the tire width direction (broken line portions at the boundary between T and N in FIG. 1) are located, that is, the block land portion rows 21 and 24 in FIG. Each of the block land portions 31 and 34 constituting the surface area S1 of the tread surface can be larger than the surface area S2 of each of the block land portions 32 and 33 constituting the other block land portion rows 22 and 23. Since the block land portion rows 21 and 24 are in contact with the end portions of the rails R, the block land portion rows 21 and 24 are more easily worn than the other block land portion rows 22 and 23. The block rigidity is higher than that of the blocks 22 and 23, and uneven wear between the block land portion rows 21 and 24 and the block land portion rows 22 and 23 can be suppressed. This surface area is assumed to be in an unloaded state in which a tire is mounted on an applicable rim and filled with a predetermined air pressure.

  S1 / S2 is preferably more than 1.0 and less than 2.0. When S1 / S2 is 1.0 or less, the block rigidity of the block land portions 31 and 34 becomes low, and the block deformation becomes large during traveling. As a result, there is a concern about a decrease in traction and wear resistance. On the other hand, when S1 / S2 exceeds 2.0, the block rigidity of the block land portions 31 and 34 is increased, and the wear resistance is improved, but the traction property is decreased. However, there is no problem in running on the track. In changing the surface area ratio S1 / S2, it is considered that when the length of the block in the tire width direction is changed, the block land portion 32 becomes small, the block rigidity cannot be secured, and becomes a generation core of uneven wear. On the other hand, when changing the tire circumferential length, it is possible to ensure the necessary traction without reducing the block rigidity. Therefore, it is preferable to adjust S1 / S2 by changing the tire circumferential length of the block.

  Next, in order to further clarify the effects of the present invention, the tires 100 and 200 (Examples 1 and 2) shown in Embodiments 1 and 2 and comparative tires (Comparative Examples 1 and 2) described below are used. The comparative evaluation performed using this will be described.

(Comparative tire 1)
As shown in FIG. 4, a tire 300 having a tread portion having a block-based pattern as a comparative tire 1 was used.

(Comparative tire 2)
In the tire 100 of the first embodiment shown in FIG. 1, a tire in which the block land portion rows 21, 22, 23, and 24 are rib-like land portions similar to the rib-like land portions 25 and 26 is referred to as a comparative tire 2. .

Items common to each pneumatic tire are as follows.
Tire size: 235 / 70R17.5
Tire internal structure: radial tire with a pair of crossed belts
(Belt cord angle: 40 ° to 74 ° with respect to the circumferential direction, one carcass)

  These tires were mounted on an applicable rim having a rim width of 17.5 × 6.75 inches, filled with an internal pressure of 750 kPa, and the following performance tests were performed. The results are shown in Table 1.

<Evaluation of track traction performance>
These tires were installed in a vehicle (Hino Profia), and a start acceleration test was conducted on a test course (track). The rail used in the test is a 50 kg N rail (rail width: 60 mm), and the rail and the tire abut so that the tire equator coincides with the center of the width of the rail top surface. The center was set as an area within 110% of the rail width, and the area was within 35% of the tread width. For the traction evaluation, the feeling evaluation of the test driver was utilized, and the evaluation point of Comparative Example 1 was set to 100, and the feeling point of the example was indexed.

<Evaluation of wear performance on road>
Rotate left and right every 1000 km by the AB method, and after running 100 km at a rate of 4000 km at a rate of 20% on the rail and 80% on the road, always measure the amount of wear in each circumferential groove. The average wear amount of the circumferential groove was calculated. From the obtained average wear amount, the service life from the start of use in each tire to the remaining groove of 1.6 mm was obtained. The service life of Comparative Example 1 was indexed as 100. That is, the larger the index, the higher the wear performance.

<Noise evaluation during road driving>
The noise when traveling on the noise measurement road surface (ISO road surface) of the test course with a vehicle equipped with each tire was evaluated by the JASO method. When the noise level of Comparative Example 1 was set to 100, the noise was reduced by half by the method of index 200. That is, the larger the index is, the better the result is that the noise is reduced.

  As is clear from Table 1, when Comparative Example 1 and Examples 1 and 2 were compared, the traction performance during track running was maintained, while the wear resistance during road running was greatly improved, and noise was reduced. Could also be reduced. In addition, when Comparative Example 2 is compared with Examples 1 and 2, the wear resistance and noise reduction effect when traveling on the road are equivalent, whereas Comparative Example 2 can maintain the traction performance during track traveling. There wasn't.

  According to the present invention, compared to the case where the entire tread portion is a block pattern, the tread portion is divided into a block land portion row and rib-like land portions on both sides thereof, and the block land portion row extends at least over the entire rail contact region. Positioning allows the traction performance during track running to be maintained, while the rib-like land portion is located in the rail non-contact area, improving wear resistance and reducing noise during road driving. It becomes.

100,200 tire 10 tread portion 11,12 circumferential groove (predetermined circumferential groove, outermost circumferential groove)
13, 14, 15 Circumferential groove 16, 17, 18, 19 Width direction groove 21, 22, 23, 24 First divided land portion (block land portion row)
25, 26 Second divided land (rib-shaped land)
31, 32, 33, 34 Block land portion 35, 36 Width direction sipe 37, 38 Circumferential direction sipe 39, 40 Width direction groove T Rail contact area N Rail non-contact area

Claims (5)

Tires used both on roads and on rails of tracks,
In the tread part,
A plurality of circumferential grooves extending along the tire circumferential direction are arranged to form a plurality of rows of divided land portions,
Among the plurality of circumferential grooves, a plurality of widthwise grooves extending at least along the tire width direction are spaced apart in the tire circumferential direction on the divided land portions on the inner side in the tire width direction of the predetermined two circumferential grooves. And at least one block land portion row composed of a plurality of block land portions is defined, and the divided land portions on the outer side in the tire width direction of the predetermined two circumferential grooves are rib-shaped land. And
The block land portion row is located at least over the entire rail contact region of the tread portion,
The rib-like land portion is located in a rail non-contact area of the tread portion ,
The surface area of the tread surface of each block land portion constituting the block land portion row where both ends in the tire width direction of the rail contact region are located is the surface area of the tread surface of each block land portion constituting the other block land portion row. Tire characterized by being larger than .   Among the rib-like land portions, the outermost rib-like land portion including the tread end in the tire-width direction has one end opened at the tread end and the other end terminated in the rib-like land portion in the width direction. The tire according to claim 1, wherein the grooves are arranged at intervals in the tire circumferential direction. The tread portion, tire according to claim 1 or 2 having a tread pattern of a point symmetry. The tire according to any one of claims 1 to 3 , wherein the tire is a summer tire. The tire according to any one of claims 1 to 4 , wherein the tire is a heavy duty tire.