JP5523799B2 - Sprocket and rubber crawler assembly including the same - Google Patents

Description

  The present invention relates to a sprocket that transmits a driving force to a rubber crawler, and a rubber crawler assembly including the sprocket.

From the viewpoints of road surface protection, noise suppression, and environmental protection, rubber crawlers have recently been used in the running parts of vehicles such as construction machinery and agricultural machinery, and the driving force is transmitted to the rubber crawlers by sprockets. It has become.
As such a rubber crawler, a rubber crawler having an inner peripheral surface on which a driving protrusion made of a rubber lump is formed at a constant pitch is widely known (see, for example, Patent Document 1). This drive protrusion (hereinafter referred to as a protrusion) is a protrusion-like object raised in a mountain shape on the inner peripheral surface of the rubber crawler, and engages a sprocket tooth attached to the drive shaft to this protrusion. To transmit the driving force to the rubber crawler.

JP 2009-78796 A

By the way, when the driving force from the sprocket teeth is transmitted to the protrusion, a high stress is partially generated in the protrusion, and the protrusion is easily damaged.
In view of the above facts, the present invention has an object to provide a sprocket capable of lowering a high stress partially generated in a protrusion for driving a rubber crawler, and a rubber crawler assembly including the sprocket. To do.

The present inventor has examined the cause of the occurrence of partial high stress in the protrusion. And since the dimension of the tooth | gear part of the sprocket was small compared with the protrusion part of a rubber crawler, it thought that a high stress produced partially in a protrusion part.
Therefore, as shown in FIG. 7, the present inventor increases the contact area between the tooth portion 501 and the protrusion portion 514 of the rubber crawler 510 by increasing the size of the sprocket tooth portion 501. We studied to reduce the stress. However, the problem that the tooth part 501 and the protrusion part 514 easily interfere with each other (particularly, the tooth part 501 easily interferes with the central part of the contact surface with the protrusion part 514) was considered.
Therefore, the present inventor has intensively studied a configuration in which such interference is unlikely to occur and high stress is not partially generated in the protruding portion 14, and the present invention has been completed.

The invention according to claim 1 includes a tooth portion that contacts a protrusion formed on an inner peripheral side of the rubber crawler and transmits a driving force to the rubber crawler, and a non-contact portion that does not contact the protrusion. The tooth portion is formed on the tooth portion, and the tooth portion is in contact with the protrusion portion at the same time at the base end side with respect to the non-contact portion and the tip end side with respect to the non-contact portion to transmit the driving force. Thus, the outer shape of the tooth portion is determined .
In the first aspect of the invention, the sprocket tooth portion simultaneously contacts the rubber crawler protrusions at two locations, ie, the base end side of the non-contact portion and the tip end side of the non-contact portion. Thus, the outer shape of the tooth portion is determined so as to transmit the driving force. Therefore, compared with the conventional case where the tooth portion is in contact with the protruding portion at only one place, the stress generated in the protruding portion can be reduced.

The invention described in claim 2 includes the sprocket according to claim 1 and a rubber crawler incorporated in the sprocket.
Thereby, since the stress which arises in a projection part when the tooth | gear part of a sprocket contact | abuts to the projection part of a rubber crawler can be made low, it can be set as a rubber crawler assembly which a projection part cannot damage easily.

According to a third aspect of the present invention, the non-contact portion is a recess formed between a proximal end and a distal end of the tooth portion.
Accordingly, these effects can be achieved while reducing the weight of the tooth portion, that is, reducing the weight of the sprocket.

According to a fourth aspect of the present invention, the outer shape of the tooth part and the protrusion part is determined so that the two parts simultaneously contact the protrusion part when the tooth part of the sprocket contacts the protrusion part. Yes.
As a result, it is possible to effectively and reliably reduce the stress generated in the protruding portion when the tooth portion contacts the protruding portion.

According to a fifth aspect of the present invention, the acute angle formed by the side surface on the rubber crawler circumferential direction side of the protrusion portion with respect to the rubber crawler circumferential direction becomes smaller toward the tip end portion of the protrusion portion, and the sprocket circumferential direction of the tooth portion The acute angle formed by the side surface with respect to the circumferential direction of the sprocket increases as it goes outward in the radial direction of the sprocket.
The protrusion of the rubber crawler usually has a shorter length in the circumferential direction of the rubber crawler as it approaches the tip of the protrusion. Accordingly, the side surface portion of the protrusion on the rubber crawler circumferential direction side is more easily damaged at the tip end of the protrusion than the base end of the protrusion. On the other hand, the protrusion is less susceptible to damage as the acute angle formed by the side surface on the rubber crawler circumferential direction side with respect to the rubber crawler circumferential direction is smaller. Therefore, according to the fifth aspect of the present invention, it is possible to further suppress damage to the side surface portion of the protrusion tip portion.
The acute angle formed by the side surface of the tooth portion in the circumferential direction of the sprocket with respect to the circumferential direction of the sprocket becomes larger toward the outer side in the radial direction of the sprocket. Therefore, the tooth portion and the protrusion portion can be satisfactorily engaged, and damage to at least one of the tooth portion and the protrusion portion due to stress concentration can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the sprocket which can reduce the high stress which arises partially in the protrusion part for a drive of a rubber crawler, and a rubber crawler assembly provided with the same.

It is the perspective view which showed a part of rubber crawler assembly which concerns on one Embodiment of this invention. It is explanatory drawing which expanded and showed the engaging part of a rubber crawler and a sprocket in one Embodiment of this invention. It is sectional drawing of arrow 3-3 of FIG. 1 which shows that a sprocket and a rubber crawler engage with one Embodiment of this invention. It is a top view of the inner peripheral surface side of the rubber crawler used in one embodiment of the present invention. It is explanatory drawing which looked at the sprocket which concerns on one Embodiment of this invention from the sprocket circumferential direction. It is a side view which shows the modification of the sprocket which concerns on one Embodiment of this invention. It is explanatory drawing which expanded and showed the engaging part with the comparative example of a rubber crawler and a sprocket.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. As shown in FIG. 1, a rubber crawler assembly 200 according to an embodiment of the present invention is provided with a sprocket 100 according to the present invention and a rubber crawler 10 to which rotational driving force is transmitted by the sprocket 100. Yes.

This rubber crawler 10 is a so-called inner peripheral drive type rubber crawler, and has a lug 12 acting on the road surface on the outer peripheral surface side, and an engagement for transmitting a driving force to the rubber crawler itself on the inner peripheral surface side. The part is formed. The engaging portion includes a hard engaging member embedded at a constant pitch in the circumferential direction of the rubber crawler 10 and a recessed portion 13 disposed between the engaging members.
For convenience of explanation, the rotation direction of the rubber crawler 10 is referred to as the circumferential direction CD of the rubber crawler 10, and the direction perpendicular thereto is referred to as the width direction RD of the rubber crawler 10.

A plurality of metal cores 15 that are hard engaging members are embedded in the rubber crawler 10 at a predetermined pitch at intervals in the circumferential direction CD, with the rubber crawler extending in the width direction RD.
The structure of the cored bar 15 will be described in detail later. As shown in the figure, a pair of corners 15a and 15a are formed at the same position in the rubber crawler width direction on the inner peripheral surface side of the central part. That is, a pair of corners 15a, 15a formed in a bifurcated shape protrudes from the inner peripheral surface of the rubber crawler 10 toward the inner side (rubber crawler inner peripheral side), which is covered with the same rubber material as the rubber crawler and protrudes It is part 14.

And the layer arrange | positioned on the outer side of the metal core 15 is a reinforcement layer extended in the endless direction (endless belt shape) to the circumferential direction CD so that each metal core 15 may be included including the steel cord (not shown). is there.
The steel cord is a tensile member embedded in the rubber crawler 10 so that the rubber crawler 10 rotates smoothly based on the driving force received from the sprocket 100 while restricting the expansion of the rubber crawler 10 in the circumferential direction CD. Assist.

A plurality of recesses 13 for receiving the teeth 101 of the sprocket 100 are formed on the inner peripheral surface of the rubber crawler 10. The recessed portion 13 has a shape in which the inner peripheral surface of the rubber crawler 10 is dented to the grounding surface side (outside) with respect to the standard inner peripheral surface as described above, and the tooth portion 101 of the sprocket 100 enters. It is formed to allow.
The indented portion 13 may be formed in the shape of a recess having a bottom surface, or may be a through-hole shape having no bottom surface.

When the dent 13 is a through-hole, a structure with improved discharge of mud, gravel and the like can be obtained. Moreover, the contact area with the tooth part 101 can be appropriately adjusted by changing the wall surface shape of the recessed part 13 with which the tooth part 101 of the sprocket 100 engages (contacts). If the wall surface of the recessed portion 13 is designed so as to increase the contact area, the surface pressure with the tooth portion 101 can be reduced.
A wheel (not shown) is a load support wheel that is provided to guide and stably drive the rubber crawler 10 while supporting a load, and a sprocket 100 serving as a drive wheel and an idler serving as a driven wheel (see FIG. (Not shown) as needed.

  FIG. 2 is an enlarged partial cross-sectional view showing an engagement portion between the rubber crawler 10 and the sprocket 100. FIG. 3 is a cross-sectional view taken along the line 3-3 in FIG. 1 showing that the sprocket 100 and the rubber crawler 10 are engaged. FIG. 4 is a plan view of the inner peripheral surface side of the rubber crawler 10. FIG. 5 is an explanatory view of the sprocket 100 as seen from the circumferential direction of the sprocket. The structure of the sprocket 100 and the rubber crawler assembly 200 will be described in more detail with reference to these drawings.

  The base portion of the core metal 15 is generally rectangular in plan view, and is embedded in the rubber crawler 10 with its longitudinal direction extending in the width direction RD. The pair of corners 15a and 15a described above are formed in the central portion of the core metal 15 in a mutually separated state.

  The corner portion 15a of the core bar 15 has a shape that is longer in the circumferential direction than the dimension in the width direction RD, and has a long shape in the circumferential direction, and the sprocket 100 and the above-described portion between the pair of corner portions 15a and 15a. It is configured so that the rolled wheels can be guided smoothly.

The interval between the pair of corners 15a, 15a is set so as to ensure an interval at which the sprocket 100 can smoothly rotate. However, the corner 15a of the metal core 15 formed of a hard material such as metal is covered with the same rubber material as the rubber crawler, and becomes a rubber-like protrusion 14 in appearance. Therefore, the sprocket 100 rotates while being guided between the two protrusions 14.
Accordingly, the distance between the pair of corner portions 15a is set to be large in consideration of the thickness of the rubber to be covered.

Now, as clearly shown in FIG. 2, the rubber crawler 10 has a metal core 15 which is a hard engagement member and an intermediate portion between which the engagement portion that receives the driving force by engaging with the tooth portion 101 of the sprocket 100 is provided. And the recessed portion 13 disposed in the.
More specifically, the metal cores 15 are arranged at equal pitches in the circumferential direction CD, and the recesses 13 receive the sprocket teeth at intervals (every period) between them. Has been placed. The dent 13 is formed so that the standard inner peripheral surface 11 of the rubber crawler 10 is recessed.
And the recessed part 13 is arrange | positioned at equal intervals to the circumferential direction CD in the center position in the width direction RD.

In the above structure, the driving force transmitted from the sprocket 100 to the rubber crawler 10 is caused by the tooth portion 101 of the sprocket 100 entering the recess portion 13 provided on the inner peripheral surface and engaging with the wall surface of the recess portion 13. It is transmitted when contact is made.
That is, by repeating the operation in which the tooth portions 101 of the rotating sprocket 100 sequentially enter the respective recessed portions 13 arranged at a constant pitch on the inner peripheral surface of the rubber crawler 10, the wall surfaces of the recessed portions 13 are sequentially pressed. The rubber crawler 10 is rotated.

  In the structure of FIG. 2 described here, the recessed portions 13 are disposed between the cored bars 15 embedded at a constant pitch as described above. In other words, in this structure, since the cored bar 15 is positioned before and after the recessed portion 13 in the circumferential direction CD, the recessed portion 13 is positioned before and after. And it becomes a strong structure in which the back part of the dent part 13 is supported by the hard metal core 15. Therefore, the tooth portion 101 of the sprocket 100 can be indirectly engaged with the cored bar 15 under the deformation of the recessed portion 13 to reliably transmit the driving force.

  Further, in the rubber crawler 10 according to the present embodiment, the tooth portion 101 of the sprocket 100 is engaged with the recess portion 13 formed so as to be recessed from the position of the standard inner peripheral surface 11 to the outer peripheral surface side. Therefore, damage to the coupling portion due to the engagement of the tooth portion 101 can be reliably suppressed. Therefore, the durability of the rubber crawler 10 is greatly improved.

  In addition, when the concave portion 13 that is recessed from the standard inner peripheral surface 11 to the outer peripheral surface is provided in this way, the engagement position (drive transmission point) with which the tooth portion 101 of the sprocket 100 engages is lowered, and thus the steel is lowered. Since the distance from the cord (not shown) to the engagement position is shortened, a rubber crawler with good driving force transmission efficiency can be obtained.

Further, the acute angle θ (see FIG. 2) formed by the side surface 14S on the rubber crawler circumferential direction side of the protrusion 14 with respect to the rubber crawler circumferential direction becomes smaller toward the front end side of the protrusion, and damage to the side surface of the protrusion 14 is caused. Is further suppressed.
Accordingly, the acute angle α2 formed by the inclined side surface 117 of the tooth tip 116 with respect to the sprocket circumferential direction is made larger than the acute angle α1 formed by the inclined side surface 113 of the base 112 described later with respect to the sprocket circumferential direction. ing. Therefore, the acute angle formed by the inclined side surface 113 of the base portion 112 and the inclined side surface 117 of the tooth tip portion 116 with respect to the sprocket circumferential direction becomes larger toward the outer side in the sprocket radial direction.

The rubber crawler 10 of the above-described embodiment is formed to include other structures that are preferably provided in addition to the above-described configuration. Hereinafter, this point will be described.
Referring to FIGS. 2 to 5 again, a raised surface 20 formed by raising a rubber material is formed on the front and back of the cored bar 15 in the circumferential direction CD. When the inner peripheral surface between the left and right protrusions 14 is lowered, the contact area with the sprocket 100 is reduced and the surface pressure is increased. Therefore, a raised surface 20 in which rubber is bulged and raised from the other standard inner peripheral surface 11 may be provided before and after the central portion of the core metal 15.

  By providing the raised surface 20 between the pair of left and right corner portions 15a in this way, the contact area between the recessed portion between the tooth portions 101 of the sprocket 100 and the inner peripheral surface of the rubber crawler 10 can be increased. it can. Thereby, the surface pressure acted on by the tooth part 101 can be reduced. In addition, you may make it the structure which does not contact the recessed part between tooth | gear parts 101 and the internal peripheral surface of the rubber crawler 10. FIG.

  By providing the raised surfaces 20 before and after the core bar 15 in this way, contact between the central portion of the core bar 15 and an idler (not shown) can be reliably prevented. If the rubber film at the center of the core 15 becomes thin due to the use of a rubber crawler for a long time, noise may occur due to unintended contact with the idler. By forming the raised surface 20 which is the surface of the raised part with a thick rubber thickness before and after the cored bar 15, noise generation can also be prevented.

Hereinafter, a structural example of the sprocket 100 that meshes with the rubber crawler 10 will be described.
As shown in FIG. 1 to FIG. 3 and FIG. 5, the sprocket 100 is required to have a structure including a tooth portion 101 that can enter a recessed portion 13 formed on the inner peripheral surface of the rubber crawler 10. In the present embodiment, the sprocket 100 includes a tooth portion that abuts on the protrusion 14 projecting toward the inner peripheral side of the rubber crawler and transmits a driving force to the rubber crawler 10.

  The tooth portion 101 is formed with a concave portion 106 that does not come into contact with the protruding portion 14 at a substantially intermediate position between the proximal end and the distal end. With this configuration, when the sprocket 100 rotates (forward rotation, reverse rotation), the tooth portion 101 is located on the proximal end side of the tooth portion with respect to the recessed portion 106 and the distal end of the tooth portion with respect to the recessed portion 106. It has a structure in which the driving force is transmitted by abutting against the protrusion 14 at two locations, the tip side abutting portion 110 located on the side.

  Here, in the present embodiment, the tooth portion 101 is fixed to the base portion 112 and the circular base plate portion 102 which is a sprocket body with a bolt or the like, and extends through the base portion 112 and extends to the tooth tip side. And a tooth tip portion 116 continuous with the tooth tip side of the extension portion 114 (see FIG. 1 and the like). The base portion 112 is formed with a through hole 112H through which the extending portion 114 passes.

  In addition, a through-hole 112M that penetrates along the thickness direction of the circular substrate portion 102 is formed in the base portion 112, and a through-hole 114M that penetrates along the thickness direction of the circular substrate portion 102 is also formed in the extension portion 114. Yes. The sprocket 100 is provided with a fixing rod 115 that is inserted into the through holes 112M and 114M and fixes the base 112 to a predetermined position in the extension 114.

  On the front and rear sides of the base 112 in the circumferential direction of the sprocket, an inclined side surface 113 that abuts against the protrusion 14 is formed. Also on the front and rear sides of the tooth tip portion 116 in the circumferential direction of the sprocket, an inclined side surface 117 that abuts against the protrusion 14 is formed. Further, the tip portion of the tooth portion 101 is rounded according to the bottom surface of the recessed portion 13.

  The base portion 112 and the extension portion 114 are so dimensioned that the base portion 112 protrudes beyond the extension portion 114 to the normal rotation side and the reverse side of the sprocket 100 of the tooth portion 101. In the extension portion 114 and the tooth tip portion 116, the tooth tip portion 116 is sized to protrude to the forward rotation side and the reverse side of the sprocket of the tooth portion 101 rather than the extension portion 114. Accordingly, the base portion 112, the extension portion 114, and the tooth tip portion 116 form a recess 106 in which the extension portion 114 is not in contact with the projection portion 14 even when the sprocket 100 is rotated. The shape is divided into a base portion 112 and a tooth tip portion 116.

  Further, when the tooth portion 101 abuts against the protrusion 14, that is, when the tooth portion 101 comes into contact with the protrusion portion 14, the base portion 112 and the tooth tip portion 116 are in the forward rotation or the reverse rotation. The outer shapes of the tooth portion 101 and the protruding portion 14, particularly the outer shapes of the inclined side surfaces 113 and 117, are set in advance so that the sprocket radius is taken into consideration.

The circular substrate portion 102 may be a single round plate-like member having a certain thickness, or a structure in which two thin disk members are prepared and arranged opposite to each other and a tooth portion is arranged therebetween. Also good.
The latter structure is a sprocket structure called a cage type, and teeth are arranged at a predetermined pitch along the peripheral edge of two thin disk members. And what is necessary is just to set so that a tooth | gear part may protrude in the radial direction outward from a disk material.

  As described above, in the present embodiment, the concave portion 106 that does not contact the protruding portion 14 is formed in the tooth portion 101, so that the tooth portion 101 is closer to the base end side than the concave portion 106, The rubber crawler 10 reaches a driving force by coming into contact with the protrusions 14 at two locations with the tooth tip 116 that is on the tip side of the recess 106. Therefore, compared to the conventional example in which the tooth portion 101 is in contact with the protrusion portion 14 at only one place, the stress generated in the protrusion portion 14 can be reduced. Further, the central portion of the contact surface of the tooth portion 101 does not easily interfere with the protruding portion 14.

  And the recessed part 106 is formed between the base end of the tooth part 101, and the front-end | tip, and while reducing the weight of the tooth part 101 (namely, weight reduction of the sprocket 100), between the base part 112 and the tooth tip part 116, it is. It can be set as the structure contact | abutted to the projection part 14 in two places.

  Further, when the tooth portion 101 abuts on the projection portion 14, the base portion 112 and the tooth tip portion 116 abut on the projection portion 14 at the same time. Thereby, when the tooth | gear part 101 contact | abuts to the projection part 14, the stress which arises in the projection part 14 can be reduced effectively reliably.

Further, the acute angle θ (see FIG. 2) formed by the side surface 14S on the rubber crawler circumferential direction side of the protrusion 14 with respect to the rubber crawler circumferential direction becomes smaller toward the front end side of the protrusion, and damage to the side surface of the protrusion 14 is caused. Is further suppressed.
In accordance with this, the acute angle α2 formed by the inclined side surface 117 of the tooth tip 116 with respect to the sprocket circumferential direction is made larger than the acute angle α1 formed by the inclined side surface 113 of the base portion 112 with respect to the sprocket circumferential direction. . Therefore, the acute angle formed by the inclined side surface 113 of the base portion 112 and the inclined side surface 117 of the tooth tip portion 116 with respect to the sprocket circumferential direction becomes larger toward the outer side in the sprocket radial direction. Thereby, the tooth part 101 and the protrusion part 14 engage favorably, and damage to at least one of the tooth part 101 and the protrusion part 14 due to stress concentration can be suppressed.

  Further, the rubber crawler 10 transmits the driving force by engaging the tooth portion 101 of the sprocket 100 with the recess portion 13 formed between the core bars 15 embedded at a constant pitch and backed up by the core bar 15. Therefore, the cored bar 15 and the recessed part 13 are not deformed or damaged by the force received from the tooth part 101 of the sprocket 100. Therefore, the durability of the rubber crawler can be improved.

  Moreover, since the position of the driving force transmission point can be brought close to the steel cord, the transmission efficiency of the driving force can be improved. And the rubber crawler 10 can be reliably driven by using together the sprocket 100 which has the tooth | gear part which protrudes outside from the outer edge of the circular board | substrate part 102 used as a base | substrate.

  Further, in the present embodiment, the concave portion 106 is formed by the base portion 112, the extension portion 114, and the tooth tip portion 116, so that the tooth portion 101 is projected at the two locations of the base portion 112 and the tooth tip portion 116. However, the present invention is not limited to this, and instead of the tooth portion 101, a tooth portion 301 having a curved concave portion 306 as shown in FIG. 6 may be formed on the sprocket.

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

10 Rubber Crawler 14 Protrusion 14S Side 100 Sprocket 101 Tooth 106 Recess (Non-contact, Recess)
113 Inclined side surfaces (2 places)
117 Inclined side surfaces (2 places)
200 Rubber Crawler Assembly 301 Teeth 306 Recess

Claims (5)

A toothed portion that contacts the protrusion formed on the inner peripheral side of the rubber crawler and transmits a driving force to the rubber crawler;
A non-contact portion that does not contact the protrusion is formed in the tooth portion, and the tooth portion is simultaneously at two locations, a proximal end side with respect to the non-contact portion and a distal end side with respect to the non-contact portion. The sprocket , wherein the outer shape of the tooth portion is determined so as to contact the protrusion and transmit a driving force. A sprocket according to claim 1;
A rubber crawler incorporated in the sprocket;
A rubber crawler assembly comprising:   The rubber crawler assembly according to claim 2, wherein the non-contact portion is a recess formed between a proximal end and a distal end of the tooth portion.   The external shape of the said tooth part and the said projection part is determined so that when the said tooth part of the said sprocket contact | abuts to the said projection part, the said 2 places contact | abuts to the said projection part simultaneously. Rubber crawler assembly. The acute angle formed by the rubber crawler circumferential direction side surface of the projection with respect to the rubber crawler circumferential direction is smaller toward the projection tip end side,
The rubber crawler assembly according to any one of claims 2 to 4, wherein an acute angle formed by a side surface of the tooth portion on the sprocket circumferential direction side with respect to the sprocket circumferential direction increases toward an outer side in the sprocket radial direction. .

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