JP2012066626A - Elastic crawler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic crawler in which flexibility is improved while suppressing the occurrence of defects in a portion to which a driving force is input when traveling.SOLUTION: A rubber crawler 10 includes: a rubber crawler body 11 which is formed into an endless belt shape by a rubber material; cored bars 14 which are embedded in the rubber crawler body 11 at intervals in the crawler circumferential direction; engaging recessed sections 24 which are formed between the adjacent cored bars 14 on the inner peripheral surface of the rubber crawler body 11 and with which a sprocket 100 is engaged; and a high hardness layer 30 which configures the surface layer portion on the crawler inner peripheral side of the rubber crawler body 11 including the engaging recessed sections 24 and is formed of high hardness rubber 30G with higher hardness than that of the other portion of the rubber crawler body 11. Thereby, the flexibility can be improved while suppressing the occurrence of the defects in the engaging recessed sections 24 to which the driving force is input when traveling.

Description

  The present invention relates to an elastic crawler.

  From the viewpoint of road surface protection, noise suppression, and environmental protection, in recent years, elastic crawlers have been widely used in traveling parts of vehicles such as agricultural machines, construction machines, and civil engineering machines. . As this type of elastic crawler, for example, the rubber crawler of Patent Document 1 is known.

  In the rubber crawler of Patent Document 1, cored bars are embedded at a constant pitch in the crawler circumferential direction, and concave portions that engage with the sprocket teeth are formed between the cored bars on the inner peripheral surface. In addition, a pair of rubber protrusions each formed by covering a pair of protrusions formed on the metal core with rubber is formed on the inner peripheral surface. In this rubber crawler, the driving force is transmitted by the teeth of the rotating sprocket contacting the wall surface of the recess and the base of the rubber protrusion.

JP 2009-78796 A

  By the way, in the portion of the rubber crawler that engages with the tooth portion of the sprocket, a driving force is repeatedly input from the tooth portion during traveling, so that trouble (for example, breakage or damage) is likely to occur. For this reason, the entire inner peripheral portion of the rubber crawler is often formed of rubber that is harder than the outer peripheral portion where the lugs are formed. Similarly, in Patent Document 1, it is considered that the entire inner peripheral portion of the rubber crawler in which the concave portion that engages with the sprocket teeth is formed by rubber harder than the outer peripheral portion.

  However, if the entire inner peripheral portion of the rubber crawler is formed of hard rubber, the bending rigidity of the rubber crawler increases and the rubber crawler becomes difficult to bend. If the rubber crawler becomes difficult to bend, power loss during driving (loss of driving force) increases, which adversely affects the fuel consumption of the vehicle.

  An object of the present invention is to provide an elastic crawler with improved flexibility while suppressing the occurrence of problems in a portion where driving force is input during traveling.

  An elastic crawler according to claim 1 is an elastic crawler main body formed in an endless belt shape by an elastic body, a plurality of core bars embedded in the elastic crawler main body at intervals in the crawler circumferential direction, and the elastic crawler main body An engagement recess formed between adjacent cores on the inner peripheral surface and engaged with a sprocket, and a surface layer portion on the inner periphery side of the crawler inner side of the elastic crawler body including the engagement recess, And a high hardness layer formed of an elastic body having a higher hardness than other portions.

  In the elastic crawler according to the first aspect, during driving, the rotating sprocket is engaged with the engagement recess, so that driving force is input to the engagement recess. The input driving force is transmitted to the elastic crawler main body (elastic crawler) through an elastic body that forms the wall portion of the engaging recess.

  Here, since the surface layer portion of the elastic crawler body including the engaging recess is a high-hardness layer formed of an elastic body having a higher hardness than the other portions of the elastic crawler body, In comparison, the hardness of the engaging recess and its periphery is increased. As a result, it is possible to suppress the occurrence of defects in the engaging recess where the driving force is repeatedly input from the sprocket during traveling. Further, since the surface layer portion of the elastic crawler body is a high hardness layer, damage to the inner peripheral surface of the elastic crawler body is suppressed.

  On the other hand, since the other part of the elastic crawler body is formed of an elastic body having a lower hardness than the elastic body forming the high hardness layer, for example, all of the elastic crawler main body is the same as the elastic body forming the high hardness layer. The bending rigidity of the elastic crawler body is lower than that formed of an elastic body having hardness. Thereby, the softness | flexibility of an elastic crawler main body (elastic crawler) improves.

  The elastic crawler according to claim 2 is the elastic crawler according to claim 1, wherein the cored bar is formed with a pair of protrusions protruding from the high-hardness layer to the inner peripheral side of the crawler with a passage space of the sprocket, The protrusions are covered with an elastic body that forms the high hardness layer.

In the elastic crawler according to the second aspect, since the protrusion is covered with the elastic body, noise (for example, metal sound) generated by the collision or friction between the sprocket and the protrusion is suppressed by the elastic body.
In particular, since the protrusion is covered with an elastic body that forms a high-hardness layer, for example, the collision between the sprocket and the protrusion compared to the case where the protrusion is covered with an elastic body that forms another part of the elastic crawler body. Or it is suppressed that a malfunction (breakage, damage, abrasion, etc.) arises in the elastic body which coat | covers protrusion by friction.

  An elastic crawler according to a third aspect is the elastic crawler according to the first or second aspect, wherein the high hardness layer is thicker at a portion corresponding to the engagement recess than at the other portion.

  In the elastic crawler according to the third aspect, the thickness of the portion corresponding to the engaging recess of the high hardness layer is made thicker than the other portions. As a result, it is possible to effectively suppress the occurrence of defects in the engaging recess and its periphery due to the input from the sprocket, and since the thickness is reduced in other portions of the high hardness layer, the elastic crawler body Flexibility can be ensured.

  The elastic crawler according to claim 4 is the elastic crawler according to any one of claims 1 to 3, further comprising a low hardness layer that forms the elastic crawler body and is laminated on an outer peripheral side of the high hardness layer. The hardness of the elastic body forming the high hardness layer is 110 to 132% of the hardness of the elastic body forming the low hardness layer.

  In the elastic crawler according to claim 4, the hardness of the elastic body forming the high hardness layer is set within a range of 110 to 132% of the hardness of the elastic body forming the low hardness layer. It is possible to improve the flexibility of the elastic crawler body (elastic crawler) by reducing the bending rigidity of the elastic crawler body while suppressing the occurrence of defects in the engaging recess.

If the hardness of the elastic body forming the high-hardness layer is less than 110% of the hardness of the elastic body forming the low-hardness layer, the hardness of the elastic body forming the high-hardness layer becomes too low and the sprocket The effect of suppressing the occurrence of defects in the engaging recess due to input decreases, or the hardness of the elastic body forming the low hardness layer becomes too high, and the effect of improving the flexibility of the elastic crawler body decreases.
On the other hand, when the hardness of the elastic body forming the high hardness layer exceeds 132% of the hardness of the elastic body forming the low hardness layer, the elastic body forming the high hardness layer and the elastic body forming the low hardness layer The hardness difference between the high hardness layer and the low hardness layer may be cracked due to distortion during traveling.
Therefore, the hardness of the elastic body forming the high hardness layer is preferably in the range of 110 to 132% of the hardness of the elastic body forming the low hardness layer.

  An elastic crawler according to a fifth aspect is the elastic crawler according to any one of the first to fourth aspects, wherein the elastic crawler constitutes the elastic crawler main body and is disposed closer to the outer circumference of the crawler than the low-hardness layer and extends in the crawler width direction on the outer circumferential surface. The lug has an outer circumferential layer formed at intervals in the crawler circumferential direction, and the hardness of the elastic body forming the outer circumferential layer is lower than the hardness of the elastic body forming the low hardness layer.

In general, at a portion where the elastic crawler is wound around a sprocket of a vehicle (hereinafter referred to as “winding portion”), the elastic crawler main body is curved along the outer periphery of the drive wheel. For this reason, in the elastic crawler according to claim 5, the hardness of the elastic body forming the outer peripheral layer of the elastic crawler body is set lower than the hardness of the elastic body forming the low hardness layer.
Thereby, the bending rigidity of an elastic crawler main body falls more, and the softness | flexibility of an elastic crawler main body (elastic crawler) further improves.

  As described above, the elastic crawler of the present invention can improve flexibility while suppressing the occurrence of problems in the portion where driving force is input during traveling.

It is a perspective view containing the partial cross section of the rubber crawler of 1st Embodiment. It is a top view which shows the internal peripheral surface of the rubber crawler of 1st Embodiment. It is a top view which shows the outer peripheral surface of the rubber crawler of 1st Embodiment. FIG. 4 is a cross-sectional view taken along line 4A-4A in FIG. FIG. 5 is a sectional view taken along line 5A-5A in FIG. FIG. 6 is a sectional view taken along line 6A-6A in FIG. It is a crawler width direction sectional view of the rubber crawler of other embodiments.

[First Embodiment]
Hereinafter, a first embodiment of the elastic crawler of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a rubber crawler 10 (an example of an elastic crawler) according to the first embodiment includes a sprocket 100 that is an example of a drive wheel of a crawler vehicle (for example, a bulldozer) and an idler that is an example of an idler wheel. It is used by being wound around (not shown).

  In the present embodiment, the circumferential direction of the rubber crawler 10 (arrow S in the figure) is described as “crawler circumferential direction”, and the width direction of the rubber crawler 10 (arrow W in the figure) is described as “crawler width direction”. . In addition, the inner peripheral side (arrow IN in the figure) of the rubber crawler 10 when the rubber crawler 10 is wound is referred to as “crawler inner peripheral side”, and the outer peripheral side of the rubber crawler 10 (arrow OUT in the figure) is “crawler”. "Outer side". The crawler width direction is orthogonal to the crawler circumferential direction.

  As shown in FIG. 1, the rubber crawler 10 has a rubber crawler main body 11 (an example of an elastic crawler main body) formed in an endless belt shape from a rubber material that is an example of an elastic body. The rubber crawler main body 11 includes a crawler main body outer peripheral portion 12 that forms the crawler outer peripheral side and a crawler main body inner peripheral portion 13 that forms the crawler inner peripheral side (see FIG. 4).

  As shown in FIG. 4, the crawler main body inner peripheral portion 13 includes a high hardness layer 30 constituting a surface layer portion (all surface layer portions) on the crawler inner peripheral side, and a low hardness layered on the crawler outer peripheral side of the high hardness layer 30. And the layer 32.

The high hardness layer 30 is formed of high hardness rubber 30G as an example of an elastic body.
The low hardness layer 32 is formed of a low hardness rubber 32G as an example of an elastic body having a lower hardness than the high hardness rubber 30G.

The hardness of the high hardness rubber 30G is set within a range of 110 to 132% of the hardness of the low hardness rubber 32G. In particular, the hardness of the high hardness rubber 30G is preferably set in the range of 78 to 90, and the hardness of the low hardness rubber 32G is preferably set in the range of 68 to 78.
The “hardness” described in the present specification is a hardness defined by JIS K6253 (type A durometer).

On the other hand, the crawler main body outer peripheral part 12 is comprised by the single layer (henceforth the outer peripheral layer 12A). This outer peripheral layer 12A is composed of a low hardness rubber 12G as an example of an elastic body. The hardness of the low-hardness rubber 12G is the same as that of the low-hardness rubber 32G or lower than that of the low-hardness rubber 32G, and is set within a range of 74 to 100% of the hardness of the low-hardness rubber 32G. In particular, the hardness of the low hardness rubber 32G is preferably set in the range of 58 to 68.
In the present embodiment, the crawler main body outer peripheral portion 12 is configured by only the outer peripheral layer 12A, but the present invention is not limited to this configuration, and the crawler main body outer peripheral portion 12 may be configured by a plurality of layers.

  As shown in FIGS. 2 and 4, a plurality of core bars 14 are embedded in the rubber crawler main body 11 (in the crawler main body inner peripheral portion 13 in the present embodiment) at intervals in the crawler peripheral direction. The metal core 14 includes a central portion 16 in the crawler width direction and a pair of wing portions 18 extending outward from the both ends of the central portion 16 in the crawler width direction.

  In the present embodiment, as shown in FIGS. 2 and 4, the center of the core metal 14 in the crawler width direction and the center of the rubber crawler body 11 in the crawler width direction coincide with each other. In addition, the code | symbol CL in a figure has shown the centerline (straight line which passes along the center of the rubber crawler main body 11) of the rubber crawler 10. FIG.

  As shown in FIGS. 1 and 4, the cored bar 14 includes a pair of protrusions 20 that protrude from the high-hardness layer 30 toward the inner periphery of the crawler with a passage space for the sprocket 100 and idler (not shown). As shown in FIG. 4, the protrusion 20 is formed at the boundary between the central portion 16 and the wing portion 18, and the portion protruding from the high hardness layer 30 is covered with the high hardness rubber 30 </ b> G. Hereinafter, a portion where the protrusion 20 protrudes from the high hardness layer 30 and is covered with the high hardness rubber 30 </ b> G will be referred to as a rubber protrusion 34. The high hardness layer 30 and the rubber protrusion 34 are integrally formed.

  In the present embodiment, as shown in FIG. 1, the sprocket 100 and idler (not shown) pass between the pair of rubber projections 34 while being guided by the rubber projections 34, and as shown in FIG. (Not shown) passes through a roller passing surface 27 described later while being guided by a rubber protrusion 34.

  As shown in FIG. 2, in the high hardness layer 30 of the crawler body inner peripheral portion 13, the engagement recess 24 in which the tooth portion 100 </ b> A of the sprocket 100 is engaged (fitted) between the core bars 14 adjacent in the crawler circumferential direction. Is formed. The engaging recess 24 is recessed toward the outer periphery of the crawler, and the bottom 24A is closed with a high hardness rubber 30G (see FIGS. 4 and 5). That is, the engaging recess 24 and the surface layer portion around it are the high hardness layer 30 and are formed of the high hardness rubber 30G. By engaging the tooth portion 100A of the sprocket 100 with the engaging recess 24, the driving force from the sprocket 100 is transmitted to the rubber crawler body 11 (rubber crawler 10). Specifically, the tooth portion 100 </ b> A of the sprocket 100 abuts against the wall surface of the engaging recess 24, and the wall surface is pressed by the tooth portion 100 </ b> A to transmit the driving force to the rubber crawler body 11.

  As shown in FIGS. 4 and 5, the high-hardness layer 30 constitutes a raised portion 40 that is raised between the pair of rubber protrusions 34 toward the inner peripheral side of the crawler. This raised portion 40 increases the contact area of the sprocket 100 with the tooth portion 100A, and the input from the tooth portion 100A to the wall surface of the engaging recess 24 is dispersed. Further, since the raised portion 40 is formed on the crawler inner peripheral side of the central portion 16 of the core metal 14, contact between the central portion 16 and an idler (not shown) is prevented, and noise (for example, metal sound) Etc.) can be suppressed.

  Further, as shown in FIGS. 2 and 5, a groove portion 42 extending in the crawler width direction is formed on the surface of the raised portion 40 on the inner peripheral side of the crawler. By this groove portion 42, distortion due to the compressive force received by the raised portion 40 of the inner peripheral portion 13 of the crawler body is relieved in the wrapping portion of the rubber crawler 10, and the occurrence of defects (for example, cracks) in the raised portion 40 is suppressed. Is done.

  As shown in FIGS. 2 and 4, the crawler main body inner peripheral portion 13 is formed with a roller passing portion 26 swelled on the inner peripheral side of the crawler on the outer side in the crawler width direction of the pair of rubber projections 34. The roller passing portion 26 is formed continuously in the crawler circumferential direction, and the crawler inner circumferential surface is flat. The crawler inner peripheral surface is a wheel passing surface 27 through which one or a plurality of roller wheels (not shown) provided between the sprocket 100 and an idler (not shown) pass. In the present embodiment, the wheel passing surface 27 is flat, but the present invention is not limited to this configuration.

  As shown in FIG. 4, in the high hardness layer 30, the thickness T1 of the portion corresponding to the engagement recess 24 is thicker than the thickness T2 of the portion outside the crawler width direction. In addition, the thickness of the portion of the high hardness layer 30 on the outer side in the crawler width direction from the portion corresponding to the engagement recess 24 is substantially constant (the thickness T2 is substantially constant). The thickness T2 is preferably set in the range of 2 to 10 mm in order to ensure the flexibility of the rubber crawler body 11 while suppressing damage to the high hardness layer 30.

  As shown in FIGS. 1 and 3, a pair of block-shaped long lugs 22A that protrude toward the outer periphery of the crawler are formed on the outer peripheral surface of the outer peripheral layer 12A in the crawler width direction across the center line CL (see FIG. 1). 4 and FIG. 6). Further, a pair of block-shaped short lugs 22B that protrude toward the outer periphery of the crawler are formed on the outer peripheral surface of the outer peripheral layer 12A in the crawler width direction across the center line CL. The pair of long lugs 22A and the pair of short lugs 22B are alternately formed at intervals in the crawler circumferential direction.

The pair of long lugs 22A extend along the crawler width direction, and the outer ends in the crawler width direction reach the end portions 11E in the crawler width direction of the rubber crawler body 11 (hereinafter simply referred to as “width end 11E”). is doing. Further, the base portion of the long lug 22A has a shape that tapers from the inside to the outside in the crawler width direction.
On the other hand, the short lug 22B extends along the crawler width direction, has a shorter length in the crawler width direction than the long lug 22A, and the outer end in the crawler width direction is in the crawler width direction from the width end 11E of the rubber crawler body 11. It is located inside (that is, the end on the outer side in the crawler width direction does not reach the width end 11E). Moreover, the base part of the short lug 22B is made into the shape which tapers toward the outer side from the crawler width direction.

  The pair of long lugs 22 </ b> A and the pair of short lugs 22 </ b> B are arranged between the adjacent core bars 14 when viewed from the crawler outer peripheral side as shown in FIG. 3. By these long lugs 22A and short lugs 22B, the weight of the crawler wheel is supported, and the traction force of the rubber crawler 10 is exhibited.

  In the present embodiment, the long lugs 22A and the short lugs 22B are formed of the low hardness rubber 12G, and the long lugs 22A, the short lugs 22B, and the outer peripheral layer 12A are integrally formed. However, the present invention is not limited to this configuration, and the rubber material forming the long lugs 22A and the short lugs 22B may be a rubber material different from the low hardness rubber 12G.

  As shown in FIG. 4, an endless belt-like reinforcing cord layer 28 extending in the crawler circumferential direction is embedded in the rubber crawler main body 11 on the crawler outer circumferential side of the core metal 14. Specifically, the reinforcing cord layer 28 is disposed on the crawler inner peripheral side of the outer peripheral layer 12A. The reinforcing cord layer 28 is for maintaining the tension of the rubber crawler 10, and is formed by rubber coating one or a plurality of reinforcing cords 28A extending along the crawler circumferential direction. In this embodiment, a steel cord having excellent tensile strength is used as the reinforcement cord 28A in order to maintain the tension of the reinforcement cord layer 28. However, the present invention is not limited to this configuration, and the tension of the reinforcement cord layer 28 is not limited. For example, a cord made of organic fiber or the like may be used as the reinforcing cord 28A as long as it has a tensile strength sufficient to maintain the strength.

As shown in FIG. 4, an intermediate rubber layer 36 having excellent adhesion is disposed in the rubber crawler main body 11 between the cored bar 14 and the reinforcing cord layer 28. The core rubber 14 and the reinforcing cord layer 28 are firmly bonded by the intermediate rubber layer 36.
In the present embodiment, as shown in FIG. 6, the intermediate rubber layer 36 is disposed along the reinforcing cord layer 28, but the present invention is not limited to this configuration, and the bottom surface of the core metal 14 ( The intermediate rubber layer 36 may be disposed only between the crawler outer peripheral surface) and the reinforcing cord layer 28.

  Next, an example of a method for manufacturing the rubber crawler 10 will be described. In addition, the manufacturing method of the rubber crawler 10 is not limited to the manufacturing method demonstrated below. The order of the following manufacturing methods may be changed as appropriate.

  First, using an extruder (not shown), a strip formed of uncured high hardness rubber 30G, a strip formed of unvulcanized low hardness rubber 32G, and an unvulcanized low hardness rubber Each of the strips formed of 12G is molded.

  Next, a belt-shaped body formed of uncured high-hardness rubber 30G is loaded into a lower mold (not shown) for crawlers, and a belt-shaped body formed of unvulcanized low-hardness rubber 32G is placed thereon. , And overlap each other with an intermediate portion in the width direction. Thereby, an unvulcanized belt-like body that becomes the crawler body inner peripheral portion 13 after vulcanization is formed. Next, the cored bar 14 is embedded in the middle part in the width direction of the unvulcanized strip (the part formed of the high hardness rubber 30G) with the tips of the pair of protrusions 20 facing the lower mold for the crawler. A plurality of the core bars 14 are arranged at intervals in the longitudinal direction on a belt-like body formed of uncured high-hardness rubber 30G.

  Next, an unvulcanized band-shaped intermediate rubber layer 36 is disposed on the bottom surface of the core metal 14 exposed from the unvulcanized band-shaped body, and an unvulcanized band-shaped reinforcing cord layer is disposed on the intermediate rubber layer 36. 28 (the rubber covering the reinforcing cord 28A is in an unvulcanized state), a belt-like body formed of uncured low-hardness rubber 12G is disposed, and an upper mold for crawler (not shown) is provided. Close and vulcanize. Thereby, the belt-shaped rubber crawler main body 11 is formed. Next, the both ends of the longitudinal direction left in the semi-cured or uncured state of the belt-shaped rubber crawler body 11 are overlapped and vulcanized. Thereby, the endless belt-like rubber crawler body 11 is formed. Here, the crawler body inner peripheral portion 13 of the belt-shaped rubber crawler body 11 is composed of the high hardness layer 30 (high hardness rubber 30G) and the low hardness layer 32 (low hardness rubber 32G). Compared with a structure in which the entire inner peripheral portion 13 is composed of the high-hardness layer 30 (high-hardness rubber 30G), the bending rigidity of the belt-shaped rubber crawler main body 11 is lowered, and it is easy to bend. Thereby, at the time of manufacture, both ends in the longitudinal direction of the belt-like rubber crawler main body 11 can be easily overlapped, the complexity of the manufacture is improved, and the productivity is improved.

Next, the effect of the rubber crawler 10 of 1st Embodiment is demonstrated.
In the rubber crawler 10, a driving force is input to the engagement recess 24 by the teeth 100 </ b> A of the rotating sprocket 100 engaging with the engagement recess 24 during traveling. The input driving force is transmitted to the rubber crawler main body 11 (rubber crawler 10) via the high hardness rubber 30G forming the wall portion of the engaging recess 24.

Here, as shown in FIG. 4, the surface layer portion of the crawler body inner peripheral portion 13 including the engagement recess 24 is formed of a high hardness rubber 30 </ b> G having a higher hardness than the other portions of the rubber crawler body 11. Since the layer 30 is used, the hardness of the engaging recess 24 and its periphery is higher than that of the other portions of the rubber crawler body 11.
Thereby, it is suppressed that a malfunction (for example, a breakage, damage, etc.) arises in the engagement recessed part 24 into which a driving force is repeatedly input from the tooth part 100A of the sprocket 100 during traveling. Further, since the surface layer portion of the rubber crawler body 11 on the inner peripheral side of the crawler is the high hardness layer 30, damage to the inner peripheral surface of the rubber crawler main body 11 is suppressed.

On the other hand, since the crawler outer peripheral side of the crawler main body inner peripheral portion 13 is the low hardness layer 32, for example, compared to the crawler main body inner peripheral portion 13 as a whole made of high hardness rubber 30 G to be the high hardness layer 30. Thus, the bending rigidity of the rubber crawler body 11 is lowered. Thereby, the softness | flexibility of the rubber crawler main body 11 (rubber crawler 10) improves.
Thereby, the power loss at the time of driving | running | working is reduced and the fuel consumption of a vehicle is reduced.

  Further, by improving the flexibility of the rubber crawler 10, the rubber crawler 10 at the time of a new article can be easily wound around the sprocket 100 and idler (not shown) of the vehicle, and further, tension can be easily applied to the rubber crawler 10.

As shown in FIG. 4, since the pair of protrusions 20 are covered with the high hardness rubber 30G and the rubber protrusions 34 are formed on the inner peripheral portion 13 of the crawler body, the sprocket 100 or the tooth portion 100A is formed with the high hardness rubber 30G. The noise (for example, metal sound etc.) generated by the collision or friction of the projection 20 is suppressed.
In particular, since the protrusion 20 is covered with the high hardness rubber 30G, for example, compared to a case where the protrusion 20 is covered with a rubber material having a lower hardness than the high hardness rubber 30G (for example, the low hardness rubber 32G). The collision (or friction) between the sprocket 100 and the tooth portion 100A and the protrusion 20 prevents the rubber material that covers the protrusion 20 from causing defects (breakage, damage, wear, etc.).

  Further, as shown in FIG. 4, since the boundary between the high hardness layer 30 and the low hardness layer 32 is formed at the width end 11E of the rubber crawler body 11, the boundary is formed on the inner peripheral surface of the rubber crawler body 11, for example. Compared with the formed one, the appearance is good, and further, cracks or the like hardly occur at the boundary between the high hardness layer 30 and the low hardness layer 32 due to strain during running.

  On the other hand, the thickness T1 of the portion corresponding to the engaging recess 24 of the high hardness layer 30 is made thicker than the thickness T2 of the portion outside the crawler width direction. Thereby, it is possible to effectively suppress the occurrence of defects in the engaging recess 24 and its periphery due to the input from the sprocket 100, and further, the crawler width is larger than the portion corresponding to the engaging recess 24 of the high hardness layer 30. Since the thickness T2 is reduced at the outer portion in the direction, the flexibility of the rubber crawler body 11 can be ensured.

  Further, in the rubber crawler 10, since the hardness of the high hardness rubber 30G is within a range of 110 to 132% of the hardness of the low hardness rubber 32G, the engagement crest 24 is input to the engagement recess 24 by input from the tooth portion 100A of the sprocket 100 during traveling. It is possible to improve the flexibility of the rubber crawler body 11 (rubber crawler 10) by reducing the bending rigidity of the rubber crawler body 11 while suppressing the occurrence of defects.

When the hardness of the high-hardness rubber 30G is less than 110% of the hardness of the low-hardness rubber 32G, the hardness of the high-hardness rubber 30G becomes too low, and the engagement recess 24 is input by the input from the tooth portion 100A of the sprocket 100. There is a risk that the effect of suppressing the occurrence of defects will be reduced, or the hardness of the low-hardness rubber 32G will become too high, and the effect of improving the flexibility of the rubber crawler body 11 may be reduced.
On the other hand, when the hardness of the high hardness rubber 30G exceeds 132% of the hardness of the low hardness rubber 32G, the hardness difference between the high hardness layer 30 and the low hardness layer 32 becomes too large, due to distortion during running, etc. There is a possibility that a crack or the like may occur at the boundary between the high hardness layer 30 and the low hardness layer 32.
Therefore, the hardness of the high hardness rubber 30G forming the high hardness layer 30 is preferably set within a range of 110 to 132% of the hardness of the low hardness rubber 32G forming the low hardness layer 32.

In particular, the hardness of the high hardness rubber 30G is preferably set within a range of 78 to 90. By setting within this range, it is possible to sufficiently ensure the flexibility of the rubber crawler body 11 while suppressing the occurrence of defects in the engagement recess 24 and the rubber protrusion 34 due to the input from the tooth portion 100A of the sprocket 100. .
The hardness of the low hardness rubber 32G is preferably set in the range of 68-78. By setting within this range, it is possible to sufficiently ensure the flexibility of the rubber crawler body 11 and to suppress the occurrence of defects (for example, damage) in the low hardness layer 32.

As shown in FIG. 1, the rubber crawler main body 11 is curved along the outer periphery of the sprocket 100 at a portion where the rubber crawler 10 is wound around the sprocket 100 of the vehicle (hereinafter referred to as “wound portion”). . For this reason, in the rubber crawler 10, the hardness of the low hardness rubber 12G forming the outer peripheral layer 12A is set lower than the hardness of the low hardness rubber 32G forming the low hardness layer 32 of the inner peripheral portion 13 of the crawler body.
Thereby, the bending rigidity of the rubber crawler body 11 is further reduced, and the flexibility of the rubber crawler body 11 (rubber crawler 10) is further improved.

The hardness of the low hardness rubber 12G is set within a range of 74 to 100% of the hardness of the low hardness rubber 32G. When the hardness of the low-hardness rubber 12G is less than 74% of the hardness of the low-hardness rubber 32G, the outer peripheral layer 12A is easily damaged by an obstacle on the traveling road surface. The layer 12A becomes hard, the bending rigidity of the rubber crawler body 11 increases, and the flexibility of the rubber crawler body 11 (rubber crawler 10) may decrease.
Therefore, the hardness of the low hardness rubber 12G is preferably set within a range of 74 to 100% of the hardness of the low hardness rubber 32G.

  In particular, the hardness of the low hardness rubber 32G is preferably set in the range of 58 to 68. By setting within this range, damage to the outer peripheral layer 12A due to obstacles on the traveling road surface can be suppressed, and the flexibility of the rubber crawler body 11 can be sufficiently secured.

  As shown in FIG. 3, in the rubber crawler 10, a pair of long lugs 22 </ b> A and a pair of short lugs 22 </ b> B are disposed between adjacent core bars 14. For this reason, on the wheel passing surface 27, the rigidity on the long lugs 22 </ b> A and the short lugs 22 </ b> B is high, and the rigidity on the wing portions 18 of the core metal 14 is also high. As a result, the rigidity step when the wheel (not shown) travels on the wheel passing surface 27 is reduced, and the vertical movement of the wheel is suppressed, and the riding comfort is improved.

[Other Embodiments]
In the first embodiment, the low hardness rubber 12G forming the outer peripheral layer 12A is a rubber having a lower hardness than the low hardness rubber 32G forming the low hardness layer 32, but the present invention is not limited to this configuration. As in the rubber crawler 50 shown in FIG. 7, the low hardness layer 56 constituting the crawler inner peripheral side of the crawler main body inner peripheral portion 53 of the rubber crawler main body 51 may be formed of the low hardness rubber 12G. In this case, since the low-hardness rubber 12G is used instead of the low-hardness rubber 32G, the types of members used at the time of manufacturing can be reduced, and the complexity of the manufacturing work can be improved.

  In the above-described embodiment, the center of the core bar 14 and the center of the rubber crawler body 11 are configured to coincide with each other. However, the present invention is not limited to this configuration, and the center of the core bar 14 with respect to the center of the rubber crawler body 11. May be shifted in the crawler width direction.

  In the above-described embodiment, the rubber crawler 10 is an elastic crawler having a configuration in which tension is held by the reinforcing cord layer 28. However, the present invention is not limited to this configuration, and the adjoining without using the reinforcing cord layer 28. As a so-called link-type elastic crawler in which the core metal 14 to be connected is connected with a ring-shaped connecting member, or the connecting portions formed on each core metal are connected to each other, and the tension of the elastic crawler is held by the connected core metal. Also good.

  Further, in the above-described embodiment, the rubber crawler 10 is configured by a rubber material as an example of an elastic body. However, the present invention is not limited to this configuration, and the rubber crawler 10 is configured by an elastomer other than rubber. Also good.

  Furthermore, in the above-described embodiment, the metal core 14 is made of metal. However, the present invention is not limited to this configuration, and the metal core 14 may be, for example, provided with sufficient rigidity with respect to the specifications of the rubber crawler 10. It may be made of resin.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

10 Rubber crawler (elastic crawler)
11 Rubber crawler body (elastic crawler body)
12 Crawler outer circumference (outer circumference of elastic crawler body)
12G low-hardness rubber (elastic body forming the outer peripheral layer)
13 Crawler inner circumference (inner circumference of elastic crawler body)
14 Core Bar 20 Projection 24 Engaging Recess 27 Roller Wheel Passing Surface 30 High Hardness Layer 30G High Hardness Rubber (Elastic Body Forming High Hardness Layer)
32 Low hardness layer 32G Low hardness rubber (elastic body forming a low hardness layer)
50 Rubber crawler 51 Rubber crawler body (elastic crawler body)
56 Low hardness layer 100 Sprocket S Crawler circumferential direction W Crawler width direction IN Crawler inner circumference OUT Crawler outer circumference T1 thickness T2 thickness

Claims (5)

An elastic crawler body formed in an endless belt shape by an elastic body;
A plurality of cored bars embedded in the elastic crawler body at intervals in the crawler circumferential direction;
An engagement recess formed between adjacent core bars of the inner peripheral surface of the elastic crawler body, and engaged with a sprocket;
A high-hardness layer formed of an elastic body having a hardness higher than that of the other part of the elastic crawler body, constituting a surface layer part on the inner peripheral side of the elastic crawler body including the engagement recess;
Elastic crawler with. The metal core is formed with a pair of protrusions that protrude from the high hardness layer to the inner peripheral side of the crawler across the sprocket passage space,
The elastic crawler according to claim 1, wherein the protrusion is covered with an elastic body that forms the high hardness layer.   The elastic crawler according to claim 1 or 2, wherein the high-hardness layer has a portion corresponding to the engagement recess having a thickness greater than that of other portions. The elastic crawler main body is configured and has a low hardness layer laminated on the crawler outer peripheral side of the high hardness layer,
The elastic crawler according to any one of claims 1 to 3, wherein a hardness of the elastic body forming the high hardness layer is 110 to 132% of a hardness of the elastic body forming the low hardness layer. The elastic crawler body has an outer peripheral layer that is formed on the outer peripheral surface of the elastic crawler main body and is arranged on the outer peripheral surface with a lug extending in the crawler width direction at intervals in the crawler peripheral direction,
The elastic crawler according to any one of claims 1 to 4, wherein a hardness of the elastic body forming the outer peripheral layer is lower than a hardness of the elastic body forming the low hardness layer.

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