JP2015221609A - Crawler unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration of a crawler unit provided with a crawler belt having a structure with ununiformity due to an element such as a lug formed thereon at a predetermined pitch.SOLUTION: A crawler unit 11 includes a drive wheel 25, a front follower wheel 21 and a rear follower wheel 22 respectively supported at a front part and a rear part of a truck frame 20, a trunk roller group including at least three or more trunk rollers 2 supported with a truck frame 11 at a distance each other in a longitudinal direction, and a crawler belt 26. The crawler belt 26 has a structure showing a periodicity in elasticity thereof that the elasticity changes periodically in the longitudinal direction at a predetermined pitch so as to transit from a high elastic deformation region via a low elastic deformation region to the high elastic deformation region. The trunk rollers 2 are disposed such that an elasticity at a part of the crawler belt 26 to which each trunk roller 2 contacts is different from those of other parts to which other trunk rollers 2 contact.

Description

  The present invention relates to a crawler traveling device that uses a crawler to travel a vehicle such as a work vehicle. Generally, the crawler traveling device includes a track frame, a front driven wheel supported on a front portion of the track frame, a rear driven wheel supported on a rear portion of the track frame, the front driven wheel, and the rear driven wheel. A wheel group including at least three or more wheels supported on the track frame at an interval in the front-rear direction between the driving wheel, the driving wheel, the front driven wheel, the wheel group, And a crawler belt wound around the rear driven wheel.

  A crawler traveling device having the above-described configuration is known from Patent Document 1. In this crawler traveling device, front and rear driven wheels are disposed at the front and rear end portions of the track frame supported by the traveling machine body, and a plurality of wheels are disposed in the middle region at intervals in the rearward direction. A crawler belt that is driven by drive wheels to which power is transmitted is wound around the front and rear driven wheels and the wheels. Further, in this crawler traveling device, the plurality of wheels are provided as a front wheel at a front portion of a swing frame swingable around a lateral pivot shaft supported by a track frame and as a rear wheel at a rear portion. Thus, when the crawler belt gets over an obstacle such as a stone, the front and rear wheels swing around the pivot shaft. The crawler belt is made of rubber, and a lug protruding at a predetermined pitch is formed on the grounding surface side.

  In such a crawler traveling device, the crawler belt is guided by the wheel and moves around during the traveling, and at that time, the crawler belt lugs periodically step on the ground. When adopting a bogie wheel structure in which the front and rear wheels swing around the lateral pivot shaft supported by the track frame, for example, when moving over a convex portion existing on the ground, for example, the front wheel Swings around the pivot shaft so that the rear wheel is lowered as it lifts up. Even if there are sudden protrusions on the running ground, the pivot shaft is prevented from moving up and down through the opposite swinging displacements of the front and rear wheels in the vertical direction. Vibration transmitted from the wheel to the track frame is reduced. However, it has been confirmed that even if the traveling ground is flat, vibrations are generated from the crawler belt to the track frame via the wheels, and consequently to the traveling machine body. In the case of a crawler belt in which lugs are formed at a predetermined pitch, it can be said that the crawler belt portion between the lugs is easy to bend and the elastic deformation of the crawler belt is large. On the contrary, the crawler belt portion where the lug is formed is difficult to bend and it can be said that the elastic deformation of the crawler belt is small. In this sense, the crawler belt employed in the present invention has a periodic elastic change structure that exhibits an elastic periodicity that transitions from a high elastic deformation region to a high elastic deformation region through a low elastic deformation region at a predetermined pitch in the longitudinal direction. I have. Such a periodic elastic change structure is considered to be a factor that causes the traveling machine body to vibrate even when traveling on a flat ground surface, but no solution has yet been taken into account.

JP 2013-14329 A

  In view of the above circumstances, an object of the present invention is to suppress vibration on a flat ground in a crawler traveling device including a crawler belt having a non-uniform structure in the longitudinal direction due to factors such as lugs formed at a predetermined pitch. is there.

  The crawler traveling device according to the present invention includes a driving wheel, a track frame, a front driven wheel supported on a front portion of the track frame, a rear driven wheel supported on a rear portion of the track frame, and the front driven wheel. A group of wheels including at least three or more wheels supported on the track frame with a space in the front-rear direction between the rear driven wheels, the drive wheels, the front driven wheels, and the wheels A crawler belt wound around the rear driven wheel, and the crawler belt periodically passes from the high elastic deformation region to the high elastic deformation region again at a predetermined pitch in the longitudinal direction. The rolling wheels are arranged so that the elasticities of the contacted portions of the crawler belt that are in contact with each other at the same time are different from each other. It is.

  According to this configuration, the respective wheels do not contact with a portion of the crawler belt that exhibits the same elasticity (elastic deformation) at the same time. The crawler belt used in the present invention has a low elastic deformation portion (low degree of elastic deformation) that is difficult to elastically deform from a high elastic deformation portion (a portion showing a high degree of elastic deformation) that is easily elastically deformed in the longitudinal direction. A periodic elastic change structure that transitions to a highly elastic deformation portion again via a portion). The period corresponds to a lag pitch in a crawler belt with a lag, for example. Accordingly, each wheel rolls on the crawler belt during traveling, and is arranged so that the degree of elastic deformation at the contact point of the crawler belt to which each wheel contacts is different at that time. . Therefore, for example, when one roller is located at a highly elastic deformation location, the other wheels are not located at such a high elasticity deformation location. Similarly, when one roller is located at a low elastic deformation location, which is a central position between two high elastic deformation locations, the other wheels are not located at such a low elastic deformation location. In this way, it has been confirmed that vibrations as in the conventional art are suppressed by always contacting each of the wheels where the rollers show different degrees of elastic deformation. This is because at least two rolling wheels are located at a high elastic deformation point where the degree of elastic deformation is the highest (or a low elastic deformation point where the degree of elastic deformation is the lowest). Therefore, it is based on the knowledge of the inventors of the present application that the vibration can be reduced by arranging all the wheels so as to have a phase difference in the half cycle of the cyclic elastic change of the crawler belt. .

  Note that if the crawler belt used in the crawler traveling device targeted by the present invention has lugs arranged at a predetermined pitch on the ground contact surface side of the crawler belt, the low-elasticity region is arranged in the lugs. It is an installation area, and one period of the elastic periodicity is an arrangement pitch of the lugs. Such a crawler belt with a lug, particularly made of rubber, contributes to running stability in the crawler running device, and is particularly suitable for use in agricultural machines.

  In one preferred embodiment of the present invention, the center-to-center distance between the wheels in the group of wheels is set to exceed the two wavelengths of the elastic periodicity. One wavelength here is a period length from the high elastic deformation portion having the highest degree of elastic deformation to the next high elastic deformation portion through the low elastic deformation portion. If there are two wavelengths or less between adjacent rolling wheels, the crawler belt portion once bent by the load applied by the rolling wheels will have the next rolling wheel before the bending recovery due to rolling of the rolling wheels is not sufficient. It is considered that the impact generated between the wheel and the crawler belt at that time causes a vibration that cannot be ignored. Therefore, by adopting the above configuration, further vibration can be suppressed.

  Based on the above-mentioned knowledge of the present inventor, it is preferable to consider the cyclic elastic change structure of the crawler belt as a whole, and the wheel groups as a whole are located at different elastic deformation portions with as large a difference as possible. For this reason, as a preferred embodiment of the present invention, in the group of wheels, the difference in elasticity of the contacted portions of the crawler belt that the wheels contact each other simultaneously is 1 / (( Number of rollers-1) It is proposed that the rollers are arranged so as to have a difference in elasticity caused by the phase difference of the wavelength. With this configuration, each wheel is arranged with an ideal phase difference in the position where elasticity is ideally different, that is, the periodicity of the elastic change.

  An embodiment in which a group of wheels is mounted on a track frame using a bogie wheel structure, that is, a rocking frame in which at least a plurality of wheel groups are supported on the track frame so as to be able to swing around a laterally-supporting shaft. An embodiment in which the front and rear wheels are configured as the front wheel and the rear wheel and incorporated as a bogie wheel unit is also suitable. By adopting this configuration, when traveling on uneven ground, for example, over obstacles such as stones, the front and rear wheels swing around the pivot shaft. Not only can the rear wheel simultaneously contact both the obstacle and the ground via the crawler belt to share and support the load, but the pivot shaft also moves up and down due to the swing of the front and rear wheels. Therefore, vibration transmitted from the wheel to the track frame is suppressed.

  In one preferred embodiment of the present invention, the distance between the centers of the front wheel and the rear wheel in the bogie wheel unit is set to an odd multiple of ½ wavelength of the elastic periodicity. . According to this configuration, when the front rolling wheel swings to one side in the vertical direction based on the cyclic elastic change structure of the crawler belt, the rear rolling wheel swings to the other side. The vertical displacement of the pivot shaft is expressed as the sum of the vertical displacement of the front rolling wheel and the vertical displacement of the rear rolling wheel. In this configuration, the front rolling wheel swings to one side in the vertical direction. When moving, the rear wheel swings to the other side, so that the vertical displacement of the front wheel and the vertical displacement of the rear wheel cancel each other, and the vertical displacement of the pivot shaft is reduced. . As a result, vibration in the vertical direction of the pivot shaft can be reduced, and vibration transmitted from the pivot shaft to the track frame is suppressed.

  When two or more bogie wheel units are provided side by side in the front-rear direction, it is preferable that the distance between adjacent bogie wheel units is shorter because the rotation stability of the crawler belt and the effect of preventing the wheel removal are obtained. It was made. However, when the distance between adjacent bogie wheel units is short, according to the knowledge of the inventor described above, the crawler belt portion once bent by the load applied by the wheel is restored to the bending caused by the rolling of the wheel. The vibration is caused by the next wheel coming before it is sufficiently performed. In consideration of such various restrictions, as one preferred embodiment of the present invention, the wheel group includes a front bogie wheel unit and a rear bogie wheel unit, and the front bogie wheel. A configuration is proposed in which the center distance between the rear wheel of the unit and the front wheel of the rear bogie wheel unit is shorter than the center distance between the front wheel and the rear wheel of the bogie wheel unit. .

  Furthermore, considering the experimental results performed by the inventors of the present application, as a preferred embodiment in which vibration is appropriately improved, the distance between the centers of the front wheel and the rear wheel in the bogie wheel unit is: The elastic periodicity has a (3 + 1/2) wavelength, and the distance between the centers of the rear wheel of the front bogie wheel unit and the front wheel of the rear bogie wheel unit is (2 + 2 + / 3) A form that is a wavelength is proposed.

  Further, when the center-to-center distance between the rear wheel of the front wheel unit and the front wheel of the rear wheel unit deviates from an integer multiple of the wavelength of the elastic periodicity, the rear wheel and the front wheel However, at the same time, it does not contact the hardest part (hard to elastically deform) of the crawler belt or the softest part (easy to be elastically deformed) of the crawler belt. As described above, vibration is suppressed in the arrangement in which the rear roller of the front roller unit and the front roller of the rear roller unit are not simultaneously in contact with the hardest part of the crawler belt or the softest part of the crawler belt. It was elucidated. On the other hand, if the center-to-center distance between the rear wheel of the first wheel unit and the front wheel of the second wheel unit is an integral multiple of the wavelength of the elastic periodicity, each is independent of the track frame. Thus, both the rear wheel of the first wheel unit that can be displaced and the front wheel of the second wheel unit periodically contact the hardest part of the crawler belt. In this case, the elastic deformation of the crawler belt at both locations is minimized, which is one of the causes for increasing the vibration. In addition, when both the rear wheel of the first wheel unit and the front wheel of the second wheel unit periodically come into contact with the softest part of the crawler belt, the elastic deformation of the crawler belt is maximized, This is also one of the causes for increasing the vibration. Accordingly, in one preferred embodiment of the present invention, the center-to-center distance between the rear wheel of the front wheel unit and the front wheel of the rear wheel unit is the wavelength of the elastic periodicity. It is set to avoid lengths that are integer multiples.

It is a schematic diagram explaining the basic principle of this invention. It is a schematic diagram further explaining the basic principle of the present invention. It is a whole side view of a tractor carrying a crawler traveling device by the present invention. It is the whole crawler traveling device side view. It is a side view which shows the vicinity of a front roller and a rear roller. It is VI-VI sectional drawing in FIG. It is explanatory drawing which shows the correlation of the displacement of a front wheel, the displacement of a rear wheel, and the displacement of a pivot.

  Before describing a specific embodiment of the crawler traveling device according to the present invention, the basic principle of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram of a crawler traveling device using a crawler belt 26 having a periodic elastic change structure. In the crawler traveling device 11, the driving wheel 25, the track frame 20, the front driven wheel 21 and the rear driven wheel 22 supported on the front and rear portions of the track frame 20, and the track frame 20 are spaced apart from each other in the front-rear direction. And a crawler belt 26. The crawler belt 26 includes a group of n rollers 2 including n rollers 2 supported by the crawler belt. In a general crawler traveling device 11, the number of rolling wheels 2: n is 10 or less. The distance between the centers of the adjacent rollers (distance between the rotation axes) is represented by L1, L2,... Ln-1.

  As is clear from a partially enlarged view of the crawler belt 26, lugs 46 are formed on the outer surface (grounding surface) at a predetermined lug pitch Pr, and the inner surface at an intermediate position between the lugs 46 and the lugs 46. An inward projection 44 is formed on the surface (see FIG. 5). The lug 46 extends substantially across the crawler belt width and has a height equal to or greater than the crawler belt body. Accordingly, when viewed from the rolling wheel 2 that presses the crawler belt 26 toward the ground, the location where the lug 46 is present is a hard location that is less likely to be elastically deformed. Become. The roller 2 relatively rolls on the inner surface of the crawler belt 26. When the roller 2 is positioned directly above the lug 46, the corresponding portion of the crawler belt 26 is not elastically deformed so much. When located between the lugs 46, the elastic deformation of the crawler belt 26 is considerably larger than when the wheel 2 is located directly above the lugs 46. From this, it can be said that the crawler belt 26 has a periodic elastic change structure showing an elastic periodicity that transitions from the high elastic deformation region to the high elastic deformation region again at the lug pitch Pr in the longitudinal direction. . This is represented in FIG. 1 in the form of a periodic waveform that repeats between hard (low elastic deformation) and soft (high elastic deformation). Here, the wavelength of the elastic periodicity of the crawler belt 26 is indicated by WL, and its half wavelength (0.5 wavelength) is indicated by WLh.

  One of the basic features of the crawler travel device 11 according to the present invention is that all crawling between the hard (low elastic deformation) and soft (high elastic deformation) of the crawler belt 26 having the above-described periodic elastic change structure. This is to assign the wheels 2 as evenly as possible. An example of the assignment of the wheels 2 is schematically shown in FIG. As can be seen from the figure, when n rolling wheels 2 are arranged, the elastic-periodic hard to soft amplitude range is equally divided into (n-1) to correspond to each elastic value (periodic amplitude value). It is preferable to arrange each wheel 2 at a position to perform. Approximately speaking, if the phase difference of WLh / (n-1) is added and the distance between the centers of the wheels 2 is set, the allocation becomes almost equal. In other words, if the position of the first wheel is used as a reference, the second wheel is separated from the first wheel by a distance between the centers by D = WLh / (n-1), and the third wheel is separated from the first wheel. 2D away. After that, it is sufficient to release D in increments. At this time, if the elastic periodicity of the crawler belt 26 is taken into consideration, the position of each wheel may be selected as a position corresponding to the same elastic value (periodic amplitude value) in the subsequent period. As illustrated in the figure, the third wheel is located at a position away from the first wheel by (WL (wavelength) -2D), or at a position away from the first wheel by (WL (wavelength) + 2D). It is also possible to arrange them.

  Next, the basic principle of the present invention in the crawler traveling device 11 in which the wheel group is configured as a bogie wheel unit will be described with reference to FIG. In the crawler traveling device 11 of FIG. 2, the wheel 2 is a front wheel 37 and a rear wheel 38 included in each of the front bogie wheel unit 23 and the rear bogie wheel unit 24. The distance between the centers of the front wheel 37 and the rear wheel 38 in the front bogie wheel unit 23 and the rear bogie wheel unit 24 is represented by Lr, and the rear wheel 38 and the rear bogie of the front bogie wheel unit 23. The distance between the centers of the roller unit 24 and the front roller 37 (the distance between bogie wheel units) is represented by Lb. In the case of such a crawler traveling device 11, in each bogie wheel unit 23, 24, when the front roller 37 swings to one side in the vertical direction in accordance with the elastic periodicity of the crawler belt 26, It is convenient for the rear wheel 38 to swing smoothly to the other side. That is, the center-to-center distance: Lr is set to be an odd multiple of ½ wavelength of the elastic periodicity (first condition). Thereby, when one of the rollers (front roller 37) is in contact with a hard (low elastic deformation) portion of the crawler belt 26, the other roller (rear wheel 38) is soft of the crawler belt 26. (High elastic deformation) It will touch the part. When one of the rollers (front roller 37) is in contact with the hard and soft intermediate (medium elastic deformation) position of the crawler belt 26, the other roller (rear roller 38) is also attached to the crawler belt 26. It will contact the hard and soft middle (medium elastic deformation) position. From this, the upper limit fluctuation range of the swing center of the bogie wheel unit becomes smaller than other arrangement patterns, and the vibration of the track frame 20 is suppressed. Furthermore, the front roller 37 and the rear roller 38 included in the front bogie wheel unit 23 and the rear bogie wheel unit 24 are hard (low elastic deformation) and soft (high elastic deformation) of the crawler belt 26. The distance between the bogie wheel units: Lb is set so that they can be allocated as evenly as possible (second condition). In the preferred example shown in FIG. 2 that satisfies the first condition and the second condition, the center distance Lr between the front wheel 37 and the rear wheel 38 is 3.5 wavelengths. Distance between bogie wheel units: Lb is (2 + 2/3) wavelength.

Next, one specific embodiment of the crawler traveling device according to the present invention will be described with reference to the drawings. FIG. 3 is a side view of a tractor employing the crawler traveling device, and FIG. 4 is a side view of the crawler traveling device.
As shown in FIG. 3, in this embodiment, the crawler traveling device 11 functions as a rear wheel of the semi-crawler type tractor 12. This tractor 12 is a four-wheel drive tractor whose specification is changed to a semi-crawler type. The tractor 12 is provided with a pair of left and right front wheels 15 that can be steered to the front of a traveling machine body 14 with a cabin 13. A rear mission case 16 is provided at the rear of the traveling machine body 14. The tractor 12 is configured so that a working device such as a rotary tiller (not shown) can be attached to the rear of the traveling machine body 14 via a hydraulic device (not shown) and a three-point link mechanism (not shown).

  As shown in FIGS. 3 and 4, the crawler traveling device 11 includes a track frame 20, a front driven wheel 21, a rear driven wheel 22, a front bogie wheel unit 23, and a rear bogie wheel unit 24. A driving wheel 25 and a crawler belt 26 are provided.

  The track frame 20 is formed long in the front-rear direction, and is composed of a square member, a plate member, a pipe member, or the like. The track frame 20 is supported on the traveling machine body 14 side so as to be able to swing back and forth around a swinging shaft (not shown) projecting horizontally from the traveling machine body 14 side.

  The front driven wheel 21 is provided on the front side of the track frame 20. The front driven wheel 21 is supported by a front bearing body 31 disposed at a free end of a tension adjusting mechanism 30 that is disposed to be inclined downward and supported on an upper surface of a front end portion of the track frame 20, and is a horizontal horizontal front support shaft. It can be rotated around 21A.

  The rear driven wheel 22 is provided on the rear side of the track frame 20. The rear driven wheel 22 is supported by a rear bearing body 32 provided at the rear end portion of the track frame 20, and is configured to be rotatable around a horizontal horizontal support shaft 22A.

  A group of wheels arranged between the front driven wheel 21 and the rear driven wheel 22 includes a front bogie wheel unit 23 and a rear bogie wheel unit 24. Between the front driven wheel 21 and the rear driven wheel 22, two pivot shafts 34A supported on the front side and the rear side of the track frame 20 are arranged, and a seesaw can swing around the pivot shafts 34A. A balance-like swing frame 34 is provided. As shown in FIGS. 4 and 5, a guide member 35 is provided on the lower end side of the swing frame 34.

  As shown in FIGS. 3 and 4, the front bogie wheel unit 23 is disposed near the front side of the track frame 20, and includes a front swing frame 34, a front wheel 37, and a rear wheel. The ring 38 is configured as one set. The front rolling wheel 37 is rotatably attached around a horizontal horizontal front axis 37 </ b> A disposed at the front portion of the swing frame 34. The rear wheel 38 is rotatably mounted around a horizontal horizontal rear axis 38 </ b> A disposed at the rear portion of the swing frame 34. The front roller 37 and the rear roller 38 have a smaller diameter than the front driven wheel 21 and the rear driven wheel 22.

  As shown in FIGS. 4 and 5, the pivot shaft 34 </ b> A is provided in the front-rear halfway portion between the front wheel 37 and the rear wheel 38. Specifically, the distance from the pivot shaft 34A to the front axis 37A and the distance from the pivot shaft 34A to the rear axis 38A are set to be substantially the same. Further, the front axis 37A and the rear axis 38A are set at positions lower than the pivot shaft 34A. Therefore, the pivot shaft 34A, the front shaft center 37A, and the rear shaft center 38A have a triangular shape with the pivot shaft 34A as the upper vertex, the front shaft center 37A as the front lower vertex, and the rear shaft center 38A as the rear lower vertex. Has been placed.

  As shown in FIGS. 3 and 4, the front bogie wheel unit 23 is attached to the track frame 20 by pivotally supporting a pivot shaft 34 </ b> A on a first bracket 40 fixed to the lower portion of the track frame 20. ing. The rear bogie wheel unit 24 is fixed to the lower portion of the track frame 20 and is attached to the track frame 20 by pivotally supporting a pivot shaft 34A on a second bracket 41 located behind the first bracket 40. It has been. The rear bogie wheel unit 24 is merely disposed behind the front bogie wheel unit 23 and has substantially the same structure as the front bogie wheel unit 23.

  The grounding surfaces of the front bogie wheel unit 23 and the rear bogie wheel unit 24 are set to be lower than the ground surfaces of the front driven wheel 21 and the rear driven wheel 22. Furthermore, even if the position of the front driven wheel 21 is moved forward and downward by the tension adjustment by the tension adjusting mechanism 30, the ground contact surfaces of the front bogie wheel unit 23 and the rear bogie wheel unit 24 are more than the front driven wheel 21. It is set to be at a low position.

  The drive wheel 25 is composed of a large-diameter disk-shaped sprocket mounted on the outer end surface of the rear axle 42 protruding sideways from the side surface of the rear mission case 16, and is equidistant from the outer peripheral edge of the sprocket. A driving claw body 43 is formed so as to line up in the circumferential direction. The drive wheel 25 is disposed above the track frame 20. Further, the drive wheel 25 is disposed above the front roller 37 and the rear roller 38. The driving wheel 25, the front driven wheel 21, and the rear driven wheel 22 are arranged in a triangular shape with the driving wheel 25 as an upper vertex, the front driven wheel 21 as a front lower vertex, and the rear driven wheel 22 as a rear lower vertex.

  The crawler belt 26 is mainly composed of an elastic body such as rubber, and the front driven wheel 21, the rear driven wheel 22, the front wheel 37 and the rear wheel 38 of the front bogie wheel unit 23, and the rear bogie wheel unit 24. It is wound around the front rolling wheel 37, the rear rolling wheel 38, and the driving wheel 25, and is configured to rotate (circulate) around a triangular path as a circumferential direction. The crawler belt 26 is formed with an inward projection 44 that protrudes radially inward of the inner peripheral surface of the crawler belt 26 in accordance with the arrangement interval of the driving claws 43 in the circumferential direction of the drive wheel 25. Although not shown, a recess in which the driving claw body 43 is fitted is formed between the inner protrusions 44 in the circumferential direction. The driving claw body 43 of the driving wheel 25 is fitted into a recess formed between the inner protrusion 44 and the inner protrusion 44 of the crawler belt 26 in the circumferential direction, so that the driving wheel 25 is transferred to the crawler belt 26. Driving force is transmitted.

  As shown in FIGS. 3 to 6, the front and rear wheels 37 and 38 of the front bogie wheel unit 23 and the front and rear wheels 37 and 38 of the rear bogie wheel unit 24 are pivotally supported. The left and right rolling elements respectively provided on the outer end and the inner end of the shaft 34A are configured as matagi rolling wheels that sandwich the inward projection 44 of the crawler belt 26. The left and right rolling elements roll on the wheel rolling surface on the inner circumferential surface of the crawler belt 26, and the inward projection 44 of the crawler belt 26 is sandwiched and guided by the left and right rolling elements. Further, the guide member 35 is guided along the inward protrusion 44 to prevent the wheel from being removed.

  As shown in FIG. 5, the crawler belt 26 is formed with a lug 46 that protrudes outward in the radial direction, and the lug 46 has a constant pitch (lag pitch) in the circumferential direction of the crawler belt 26. It is provided with Pr. Further, a cored bar 45 is embedded in the crawler belt 26 at a portion corresponding to the location where the inward projection 44 is formed at a constant pitch Pr equal to the lug pitch along the circumferential direction. The inward protrusions 44 are also formed at a constant pitch Pr that is the same as the lug pitch. In this embodiment, as is apparent from FIG. 5, the inward projection 44 and the cored bar 45 are arranged at just the intermediate position between the adjacent lugs 46. Such a structure is an example of the periodic elastic change structure as described with reference to FIG. 1. Therefore, the crawler belt 26 has a lug pitch Pr and passes from the high elastic deformation region to the high elastic deformation region again. The elastic periodicity that shifts to. The low elastic deformation region is a location where the lug 46 is formed, and the high elastic deformation region is a location which is intermediate between the adjacent lugs 46. At the location where the lug 46 is formed, the elastic deformation of the crawler belt 26 in the vertical direction with respect to the contact surface is small (hard), and the elastic deformation of the crawler belt 26 increases (softer) as the distance from the lug formation location increases. In other words, the crawler belt 26 has high rigidity at a location where the lug 46 is formed, and has low rigidity at a location that is intermediate between the adjacent lugs 46. This elastic periodic wavelength WL corresponds to the lag pitch Pr (see FIG. 5).

  With this rolling wheel arrangement pattern, when the front rolling wheel 37 swings to one side in the vertical direction according to the hard part and the soft part of the crawler belt 26, the rear rolling wheel 38 is on the other side in the vertical direction. Swing to. As a result, in response to the periodic elastic change (hard-soft change) of the crawler belt 26, the front roller 37 and the rear roller 38 are swung to the opposite side in the vertical direction. The vertical movement of the pivot shaft 34A is suppressed by the side swing.

  That is, as can be understood from FIG. 5, when the front roller 37 is located at the formation position of the lug 46, which is a low elastic hard region (high rigidity region), the rear roller 38 is highly elastic soft region (low It is located at the formation location of the cored bar 45 which is a rigid region. On the contrary, when the front roller 37 is positioned at the core 45 where the highly elastic soft region is formed, the rear wheel 38 is positioned at the lug 46 where the low elastic hard region is formed. .

  Further, since the center-to-center distance between the front axis 37A of the front roller 37 and the rear axis 38A of the rear roller 38 is 3.5 times the lug pitch Pr of the crawler belt 26, the front roller The oscillating radii of the rear wheel 37 and the rear wheel 38 are large and advantageous. However, the center-to-center distance between the front axis 37A of the front roller 37 and the rear axis 38A of the rear wheel 38 is 1.5 times the distance of the lag pitch Pr and 2.5 times the distance. It may be 5 times the distance.

  When the rolling wheel arrangement pattern set in this way is introduced, it is experimentally determined how the front and rear wheels 37 and 38 swing and how the pivot shaft 34A is displaced in the vertical direction. Since it confirmed, it demonstrates based on the typical graph of FIG. When the front roller 37 is displaced upward from the initial reference position, the rear roller 38 is displaced downward from the initial reference position. Conversely, when the front roller 37 is displaced downward from the first reference position, the rear roller 38 is displaced upward from the initial reference position. In other words, as shown in FIG. 7, the wave indicating the time change of the vertical displacement of the front wheel 37 and the wave indicating the time change of the vertical displacement of the rear wheel 38 are shifted from each other by about 180 degrees. The relationship is antiphase. Accordingly, since the vertical displacement of the front roller 37 and the vertical displacement of the rear wheel 38 cancel each other, as shown in FIG. 7, there is almost no vertical displacement on the pivot shaft 34A. As a result, vibration transmitted from the pivot shaft 34A to the track frame 20 is suppressed.

  By equipping the tractor 12 with the crawler traveling device 11 according to the present invention, vibration transmitted from the track frame 20 to the traveling machine body 14 side can be reduced, and in particular, the vibration reducing effect when the tractor 12 travels on flat ground is increased. The riding feeling of the tractor 12 can be improved.

[Another embodiment]
(1) In the above-described embodiment, the crawler belt 26 is assumed to have an elastic periodicity similar to a sine wave. However, the periodicity similar to a sawtooth wave having different rising and falling lengths. It may be. The present invention can be suitably applied to any crawler belt 26 that exhibits periodicity such that a hard spot (low elasticity spot or high rigidity spot) and a soft spot (high elasticity spot or low stiffness spot) repeat.

  (2) In the above embodiment, an example in which the wheel group disposed between the front driven wheel 21 and the rear driven wheel 22 is configured only by the front bogie wheel unit 23 and the rear bogie wheel unit 24. However, the present invention is not limited to this. One having only one bogie wheel unit, three or more members, or a combination of a bogie wheel unit and a non-bogie wheel unit or a fixed wheel may be used.

  (3) In the above embodiment, the crawler belt 26 is mainly composed of an elastic body such as rubber. However, the present invention is not limited to this, and the crawler belt 26 is mainly composed of a metal body such as iron. Also good.

  (4) In the above embodiment, the crawler traveling device 11 is provided as an example on the tractor 12. However, the crawler traveling device 11 is not limited to this, and the crawler traveling device 11 can be used for other work vehicles such as a combine and a construction machine. It may be equipped.

2: Rolling wheel 11: Crawler traveling device 14: Traveling machine body 20: Track frame 21: Front driven wheel 22: Rear driven wheel 23: Front bogie wheel unit 24: Rear bogie wheel unit 25: Drive wheel 26: Crawler belt 34: oscillating frame 34A: pivot shaft 37: front wheel 38: rear wheel 45: core metal 46: lug

Claims (9)

Driving wheels,
Track frame,
A front driven wheel supported at the front of the track frame;
A rear driven wheel supported at the rear of the track frame;
A group of wheels including at least three or more wheels supported on the track frame at a distance in the front-rear direction between the front driven wheel and the rear driven wheel;
A crawler belt wound around the driving wheel, the front driven wheel, the wheel group, and the rear driven wheel;
The crawler belt has a periodic elastic change structure showing an elastic periodicity that transitions from a high elastic deformation region to a high elastic deformation region through a low elastic deformation region at a predetermined pitch in the longitudinal direction;
A crawler traveling device in which the rollers are arranged so that the elasticity of the contacted portions of the crawler belts to which the rollers contact each other at the same time is different.   The crawler traveling device according to claim 1, wherein a distance between centers of the wheels in the group of wheels is set to exceed two wavelengths of the elastic periodicity.   In the group of wheels, the difference in elasticity of the contacted portion of the crawler belt with which each of the wheels contacts at the same time is caused by a phase difference of 1 / (number of wheels-1) wavelength of the elastic periodicity. The crawler traveling device according to claim 1, wherein the crawler traveling device is arranged so as to have a difference in elasticity.   At least a plurality of the wheel groups are configured as the front wheel and the rear wheel at the front and rear portions of a swing frame that is swingably supported by the track frame around a lateral pivot shaft. The crawler traveling device according to any one of claims 1 to 3, wherein the crawler traveling device is incorporated as a wheel unit.   The crawler traveling device according to claim 4, wherein a distance between centers of the front wheel and the rear wheel in the bogie wheel unit is an odd multiple of a half wavelength of the elastic periodicity.   The wheel group includes a front bogie wheel unit and a rear bogie wheel unit, the distance between the centers of the rear wheel of the front bogie wheel unit and the front wheel of the rear bogie wheel unit is: The crawler travel device according to claim 4 or 5, wherein a distance between centers of the front wheel and the rear wheel in the bogie wheel unit is shorter.   The distance between the centers of the front wheel and the rear wheel in the bogie wheel unit is the (3 + 1/2) wavelength of the elastic periodicity, and the rear wheel and the rear bogie of the front bogie wheel unit. The crawler traveling device according to claim 6, wherein a distance between centers of front rolling wheels of the rolling unit is the (2 + 2/3) wavelength of the elastic periodicity.   The center distance between the rear wheel of the front bogie wheel unit and the front wheel of the rear bogie wheel unit avoids a length that is an integral multiple of the wavelength of the elastic periodicity. 8. The crawler traveling device according to 7.   Lugs are arranged at a predetermined pitch on the ground contact surface side of the crawler belt, the low elastic deformation region is the lug arrangement region, and one period of the elastic periodicity is an arrangement pitch of the lugs. Item 9. The crawler traveling device according to any one of Items 1 to 8.

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