JP2005132135A - Crawler connector, bush for connecting crawler, and pin for connecting crawler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crawler connector, a crawler connecting bush, and a crawler connecting pin in which the generation of abnormal noise is suppressed, and friction is reduced. <P>SOLUTION: The crawler connector comprises a pair of track links 25 and 25 which have outer links 26 on one side in the longitudinal direction, and inner links 29 on the other side in the longitudinal direction, and are connected in an endless manner, a bush 30 provided to connect the inner links 29 and 29 of the pair of track links 25 and 25, and a pin 27 which are inserted in the bush 30 with both ends fitted to the outer links 26 and 26, and provided to connect the outer links 26 and 26. A sintered alloy of a porosity of 2-20% with resin having a self-lubricating characteristic impregnated therein is provided on at least either of the outer circumferential surface 30A of the bush 30 and the outer circumferential surface 27A of the pin 27. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a crawler belt coupling device, a crawler belt coupling bush and a crawler belt coupling pin suitable for use in a tracked vehicle such as a hydraulic excavator and a hydraulic crane, and more particularly, to suppress the generation of abnormal noise and wear. The present invention relates to a crawler belt coupling device, a crawler belt coupling bush, and a crawler belt coupling pin.

  2. Description of the Related Art Generally, a crawler belt used in a tracked vehicle such as a hydraulic excavator is composed of a plurality of plate-like shoes constituting a ground contact surface and a plurality of crawler belt coupling devices that couple these shoes so as to be rotatable. . The crawler belt coupling device has an outer link portion formed on one side in the longitudinal direction and an inner link portion formed on the other side in the longitudinal direction, and a pair of track links connected endlessly to each other, and the pair of track links. A bush provided to connect between the inner link parts, and a pin inserted into the bush and fitted to the outer link part at both ends, and provided to connect the outer link parts. Yes.

  The crawler belt configured as described above is provided by being wound between a driving wheel (sprocket) and a driven wheel (idling wheel). Then, when the driving wheel is rotationally driven by a traveling hydraulic motor or the like, the driving force of the driving wheel is transmitted to the crawler track while the drive wheel and the outer peripheral surface of the bush slide, so that the crawler belt is driven. Circulation is driven between the wheel and the driven wheel.

  As a prior art of such a crawler belt coupling device, there is a crawler belt coupling device having a seal device provided so as to sandwich the bush from both sides between the outer link portion and the bush (see, for example, Patent Document 1). With this sealing device, grease is sealed between the bush and the pin to improve the lubricity of the sliding surface between the bush and the pin.

JP 2001-88755 A

However, there are the following problems in the above-described prior art.
That is, generally, the sealing device used in the above-described prior art is composed of an elastic resin material such as urethane rubber. Therefore, the sealing device tends to be gradually deteriorated and lose elastic force by long-term use, and the sealing function is lowered. Therefore, when the sealing device deteriorates, the grease sealed between the bush and the pin flows out to the outside and slides in a dry environment, which may cause abnormal noise and promote wear.

  In the above prior art, grease lubrication is performed using a seal device for sliding between the bush and the pin, but no consideration is given to sliding between the drive wheel and the bush, and sliding in a dry environment is not considered. It was in a moving state. Therefore, this may cause the generation of abnormal noise and the promotion of wear.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a crawler belt coupling device, a crawler belt coupling bush, and a crawler belt coupling device that can suppress the generation of abnormal noise and reduce wear. To provide a pin.

  (1) In order to achieve the above object, the crawler belt coupling device of the present invention has an outer link portion formed on one side in the longitudinal direction and an inner link portion formed on the other side in the longitudinal direction, and is connected endlessly. A pair of track links, a bush provided to connect the inner link portions of the pair of track links, and both ends of the track links are fitted into the outer link portions and the outer link portions are inserted into the bushes. A sintered alloy having a porosity of 2 to 20% is provided on at least one of the inner peripheral surface of the bush and the outer peripheral surface of the pin.

  Generally, in a crawler belt coupling device, a seal device is provided between the outer link portion of the track link and the bush so that the bush is sandwiched from both ends, and grease is sealed between the bush and the pin by the seal device. It improves the lubricity of the sliding surface.

  Here, the sealing device usually deteriorates gradually with long-term use and loses elastic force, and the sealing function tends to be lowered. When the sealing function is thus lowered, the grease sealed between the bush and the pin flows out to the outside, and the bush and the pin are in a sliding state in a dry environment. Therefore, for example, in the crawler belt coupling device having the structure as described above, the inner peripheral surface of the bush made of a metal material and the outer peripheral surface of the pin slide directly in a dry environment. There was a possibility of causing the occurrence of wear and acceleration of wear.

  On the other hand, in the crawler belt coupling device of the present invention, by providing a sintered alloy having a porosity of 2 to 20% on at least one of the inner peripheral surface of the bush and the outer peripheral surface of the pin, wax or It is possible to impregnate a resin having self-lubricating properties. As a result, even when the grease between the bush and the pin flows out due to deterioration of the sealing device as described above, the wax impregnated in the sintered alloy or the resin having self-lubricating properties is slid from the pores to the sliding surface. It is possible to ensure the lubricity of the sliding surface between the bush and the pin. Therefore, it is possible to suppress the generation of abnormal noise due to sliding between the bush and the pin and reduce wear on the sliding surface.

  (2) In order to achieve the above object, the crawler belt coupling device of the present invention has an outer link portion formed on one side in the longitudinal direction and an inner link portion formed on the other side in the longitudinal direction, and is connected endlessly. A pair of track links, a bush provided so as to connect the inner link portions of the pair of track links, and both ends are fitted into the outer link portions and the outer links are inserted into the bushes. It consists of pins provided so as to connect the parts, and a sintered alloy having a porosity of 2 to 20% is provided on the outer peripheral surface of the bush.

  In general, a crawler belt is composed of a plurality of shoes constituting a ground contact surface and a plurality of crawler belt coupling devices that connect the plurality of shoes to each other so as to be able to rotate, and between the driving wheel (sprocket) and the driven wheel. It is provided by winding. When the driving wheel is rotationally driven by a traveling hydraulic motor or the like, the driving force of the driving wheel is transmitted to the crawler belt while the drive wheel and the outer peripheral surface of the bush constituting the crawler belt coupling device slide. Thus, the crawler belt is driven to circulate between the driving wheel and the driven wheel.

  At this time, for example, in the crawler belt coupling device having the structure as described above, the seal device provided between the outer link portion of the track link and the bush so as to sandwich the bush from both ends is provided between the bush and the pin. Grease was added to improve the lubricity of the sliding surface, but no consideration was given to the sliding between the driving wheel that drives the crawler belt and the bushing, and the sliding state was in a dry environment. It was. Therefore, the drive wheel made of a metal material and the outer peripheral surface of the bush slide directly in a dry environment, which may cause abnormal noise and promote wear.

  On the other hand, in the crawler belt coupling device of the present invention, by providing a sintered alloy having a porosity of 2 to 20% on the outer peripheral surface of the bush, the sintered alloy is impregnated with wax or a resin having self-lubricating characteristics. Is possible. As a result, when the drive wheel and the bush slide, the wax impregnated in the sintered alloy or the resin having self-lubricating characteristics flows out from the pores to the slide surface, and the slide surface between the drive wheel and the bush The lubricity can be ensured. Therefore, it is possible to suppress the generation of abnormal noise due to sliding between the drive wheel and the bush and reduce wear on the sliding surface.

  (3) In the above (1) or (2), preferably, the sintered alloy is impregnated with wax or a resin having self-lubricating properties.

(4) In the above (1) or (2), preferably, the sintered alloy is impregnated with a grease-based lubricant in which an extreme pressure material based on a high viscosity oil is added.
Thereby, for example, when seizure is likely to occur on the sliding surface, the extreme pressure material reacts with the metal surface of the sintered alloy due to the high temperature state so that the reaction product covers the metal surface. can do. In general, this reaction product has lubricity, so that seizure can be prevented.

(5) In the above (1) or (2), preferably, the sintered alloy is impregnated with any of molybdenum disulfide, lead, copper, and a mixture thereof.
For example, a molybdenum compound such as molybdenum disulfide is a solid having a layered crystal structure, and has a property that a bonding force between layers is weak and resistance to slip deformation is small. Therefore, it is generally used as a solid lubricant.

  According to the present invention, a solid lubricant such as molybdenum disulfide, lead, copper, or a mixture thereof is impregnated into a sintered alloy together with a lubricating oil, for example, so that a sliding surface can be formed from the pores of the sintered alloy during sliding. In addition, these solid lubricants can flow out together with the lubricating oil, and the lubricity on the sliding surface can be further improved.

(6) In the above (1) or (2), preferably, the sintered alloy is surface-treated by any one of carburizing, nitronitriding, laser quenching, and ion plating.
Thereby, the wear resistance of the sliding surface can be improved. Therefore, even when foreign matter such as earth and sand enters between the bush and the pin from the outside due to deterioration of the sealing device, early wear of the bush and the pin due to the foreign matter can be prevented.

(7) In the above (1) or (2), preferably, the clearance between the inner peripheral surface of the bush and the outer peripheral surface of the pin is 0.05 to 0.2 mm.
As described in the above (1), when the sealing device is deteriorated and the sealing function is lowered, the grease enclosed between the bush and the pin flows out and slides in a dry environment. There is a risk of promoting wear.

  Here, in order to suppress the abnormal wear when the grease flows out in this way, for example, a structure in which the clearance between the bush and the pin is set excessively in advance can be considered. However, in such a case, a rattling noise generated between the bush and the pin may cause abnormal noise even before the seal device deteriorates. There is a possibility that the bush may be damaged by a large load.

  According to the present invention, the lubrication between the bush and the pin can be maintained even when the sealing device deteriorates and the grease flows out as described in (1) above. Therefore, it is not necessary to set excessively, and the clearance can be set to an appropriate value. In other words, by setting the clearance between the inner peripheral surface of the bush and the outer peripheral surface of the pin to be in the range of 0.05 to 0.2 mm, abnormal noise such as rattling that may occur when the above clearance is large and damage to the bush Can be prevented.

  (8) In the above (1) or (2), preferably, the sintered alloy contains 3 to 20 wt% of copper.

  (9) In order to achieve the above object, the crawler belt coupling bush of the present invention connects the inner link portions respectively formed on one side in the longitudinal direction of a pair of track links that are endlessly connected to each other. A sintered alloy having a porosity of 2 to 20% is provided on at least one of the inner peripheral surface and the outer peripheral surface.

  (10) In order to achieve the above object, the crawler belt connecting pin of the present invention is formed on one side in the longitudinal direction of a pair of track links which are inserted into the bush and both ends thereof are connected to each other endlessly. The outer link portions are provided so as to be connected to each other by being fitted to each other, and a sintered alloy having a porosity of 2 to 20% is provided on the outer peripheral surface.

  According to the first aspect of the present invention, by providing a sintered alloy having a porosity of 2 to 20% on at least one of the inner peripheral surface of the bush and the outer peripheral surface of the pin, the sintered alloy is waxed or self-lubricated. It is possible to impregnate a resin having characteristics. Thereby, even when the grease between the bush and the pin flows out due to deterioration of the sealing device, the wax impregnated in the sintered alloy or the resin having self-lubricating characteristics flows out from the pores to the sliding surface, Lubricity between the bush and the pin can be ensured. Therefore, it is possible to suppress the generation of abnormal noise due to sliding between the bush and the pin and reduce wear on the sliding surface.

  According to the second aspect of the present invention, by providing a sintered alloy having a porosity of 2 to 20% on the outer peripheral surface of the bush, the sintered alloy can be impregnated with wax or a resin having self-lubricating properties. It is. As a result, when the drive wheel and the bush slide, the wax impregnated into the sintered alloy or the resin having self-lubricating characteristics flows out from the pores to the sliding surface, thereby improving the lubricity between the drive wheel and the bush. Can be secured. Therefore, it is possible to suppress the generation of abnormal noise due to sliding between the drive wheel and the bush and reduce wear on the sliding surface.

Embodiments of a crawler belt coupling device, a crawler belt coupling bush and a crawler belt coupling pin of the present invention will be described below with reference to the drawings.
First, an embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the crawler belt coupling device of the present invention is applied to a medium-sized hydraulic excavator having an operating mass of about several tens of tons.

FIG. 1 is a side view showing the overall structure of a hydraulic excavator provided with an embodiment of a crawler belt coupling apparatus of the present invention.
In FIG. 1, 1 is a traveling body, 2 is a revolving body mounted on the traveling body 1 so as to be able to swivel, 3 is a cab provided on one side (left side in FIG. 1) on the revolving body 2, and 4 The engine room 5 provided on the other side (right side in FIG. 1) on the revolving structure 2 is a working device provided on the operation room 3 side on the revolving structure 2. 2, an operation room 3, an engine room 4, and a work device 5.

  Reference numeral 6 denotes a boom provided on the revolving body 2 so as to be able to move up and down, 7 denotes a boom hydraulic cylinder for driving the boom 6, 8 denotes an arm provided rotatably at the tip of the boom 6, and 9 denotes the arm 8. A hydraulic cylinder for driving arm 10 is a bucket rotatably provided at the tip of the arm 8, 11 is a hydraulic cylinder for bucket for driving the bucket 10, and the working device 5 includes the boom 6, the arm 8, A bucket 10 and hydraulic cylinders 7, 9, and 11 are roughly configured.

  12 is a substantially H-shaped track frame in plan view, 13 is a side frame provided on both the left and right sides of the track frame 12, and 14 is at the rear end (right end in FIG. 1) of the left and right side frames 13, respectively. Drive wheels (sprockets) that are rotatably supported, 15 is a traveling hydraulic motor that drives the drive wheels 14, and 16 is rotatable in the vicinity of the front ends (left ends in FIG. 1) of the left and right side frames 13 respectively. A supported driven wheel (idler) 17 is a crawler belt in which a driving wheel 14 and a driven wheel 16 on both the left and right sides are wound, and the driven wheel 16 drives the driving wheel 14 via the crawler belt 17. It is rotated by force. Also, a plurality of upper rollers 18 are provided on the upper sides of the side frames 13 on both the left and right sides to guide the crawler belts 17, and a plurality of rollers 19 are provided on the lower sides of the side frames 13 on both the left and right sides to guide the crawler belts 17. Lower roller. The traveling body 1 includes these track frame 12, left / right side frames 13, 13, left / right driving wheels 14, 14, left / right traveling hydraulic motors 15, 15, left / right driven wheels 16, 16, The left and right crawler belts 17 and 17, an upper roller 18, and a lower roller 19 are roughly configured.

  2 is a partially enlarged perspective view showing the detailed structure of the crawler belt 17. FIG. 3 is a top view showing the detailed structure of the crawler belt 17 in a partial cross section. 4 is a cross-sectional view taken along the line IV-IV in FIG.

  2 to 4, reference numeral 23 denotes a plurality of shoes made of a metal plate constituting the ground contact surface of the crawler belt 17, and the plurality of shoes 23 are connected to each other by a crawler belt connecting device 24 so as to be rotatable. 25 is a pair of left and right inside the shoe 23 (upper side in FIGS. 2 and 4, front side in FIG. 3) (a pair in the short direction of the crawler belt 17 (vertical direction in FIG. 3, horizontal direction in FIG. 4)) A track link fixed by welding or the like so as to be arranged in parallel, and a pair of track links 25 provided on each of the plurality of shoes 23 are connected endlessly to each other so that the shoe 23 is connected endlessly. Thus, the crawler belt 24 is formed.

  Reference numeral 26 denotes an outer link portion formed on one side in the longitudinal direction of the track link 25 (left side in FIG. 3). The outer link portion 26 has a pin 27 for connecting the pair of track links 25, 25 to each other. The pin insertion hole 26A to be inserted and the inner side of the outer link portion 26 (center side in the short direction of the crawler belt 17) are formed with a larger diameter than the pin insertion hole 26A, and a sealing device 28 (described later) is attached. The seal mounting hole 26B is formed as a stepped hole. Reference numeral 29 denotes an inner link portion formed on the other side in the longitudinal direction of the track link 25 (the right side in FIG. 3). The inner link portion 29 has a bush insertion hole 29A into which the bush 30 is inserted. .

  Both ends of the bush 30 are inserted into the bush insertion holes 29A and 29A of the inner link portions 29 and 29 in a press-fit state, and are provided so as to connect the inner link portions 29 and 29. Yes. The pin 27 is made of, for example, a metal material such as boron steel, and is slidably inserted into the bush 30. Both ends of the pin 27 are press-fitted into the pin insertion holes 26A and 26A of the outer link portions 26 and 26. It is inserted in a state. The pin 27 may be made of, for example, carbon steel or alloy tool steel in addition to the boron steel material.

The sealing device 28 is an annular sealing member made of an elastic resin material such as urethane rubber or nitrile rubber. The sealing device 28 is mounted in a seal mounting hole 26B provided in the outer link portion 26, and the pin 27 is inserted therethrough. Accordingly, the bush 30 is disposed so as to be in contact with both ends. The seal device 28 prevents grease G (see FIGS. 5 and 6 described later) supplied between the bush 30 and the pin 27 from leaking to the outside, and between the bush 30 and the pin 27. It plays a role in blocking foreign materials such as earth and sand from entering.
The pair of sealing devices 28 and 28, the pair of track links 25 and 25, the pin 27, and the bush 30 constitute the crawler belt coupling device 24.

In the basic configuration as described above, the greatest feature of the present embodiment is that the bush 30 is made of a sintered alloy having a porosity of 2 to 20%, and the pores are impregnated with a resin having self-lubricating characteristics. It was made to. The details will be described below. 5 is a cross-sectional view taken along the line V-V in FIG. 4 showing the cross-sectional structure of the bush 30 and the pin 27, and FIG. 6 is an enlarged view of a portion A in FIG. 5 showing the sliding surface between the bush 30 and the pin 27. .
5 and 6, C is a clearance provided between the inner peripheral surface 30A of the bush 30 and the outer peripheral surface 27A of the pin 27. In this embodiment, the clearance C is set to about 0.15 mm. ing. The clearance C between the pin 27 and the bush 30 is filled with grease G. The clearance C is preferably in the range of 0.05 to 0.2 mm. If it is smaller than 0.05 mm, the assembly becomes very difficult, and if it is larger than 0.2 mm, the backlash between the bush 30 and the pin 27 is large, which may cause abnormal noise due to rattling noise or damage to the bush 30. Because there is.

  The bush 30 is made of a sintered alloy containing 3 to 20 wt% of copper and having a porosity of about 10%, for example, and 31 is a pore in the sintered alloy. Reference numeral 32 denotes a resin (or a wax) having a self-lubricating characteristic impregnated in the pores 31. Note that the porosity of the bush 30 is preferably about 2 to 20%. That is, when the porosity is less than 2%, the amount of impregnation of the resin becomes insufficient, and there is a possibility that sufficient lubricity cannot be exhibited in a dry environment (details will be described later). On the other hand, when the porosity is larger than 20%, the mechanical strength of the bush 30 itself decreases.

Next, the operation and action of one embodiment of the crawler belt coupling device, the crawler belt coupling bush and the crawler belt coupling pin of the present invention configured as described above will be described below.
The hydraulic excavator according to the present embodiment travels by rotating the drive wheels 14 by the traveling hydraulic motor 15 to circulate the crawler belt 17 between the drive wheels 14 and the driven wheels 16.

  At this time, in the crawler belt coupling device 24, the bush 30 and the pin 27 slide. The sliding surface of the bush 30 and the pin 27 is maintained in lubricity by the grease G sealed between the bush inner peripheral surface 30A and the pin outer peripheral surface 27A (that is, clearance C) by the sealing devices 28, 28. ing.

  Here, since the sealing device 28 is made of an elastic resin material such as urethane rubber or nitrile rubber as described above, the sealing device 28 tends to gradually deteriorate with long-term use and lose its elastic force, and the sealing function tends to decrease. is there. When the sealing function is thus lowered, the grease G enclosed between the bush inner peripheral surface 30A and the pin outer peripheral surface 27A flows out to the outside, and the bush 30 and the pin 27 are in a sliding state in a dry environment. There is a fear. At this time, for example, in the crawler belt coupling device having the structure as described above, the bush 30 and the pin 27 made of a metal material slide directly in a dry environment. There was a risk of inviting promotion.

  On the other hand, in the crawler belt coupling device 24 of the present embodiment, the bush 30 is made of a sintered alloy having a porosity of 2 to 20%, and the pores 31 are impregnated with a resin 32 having self-lubricating characteristics. Let As a result, even when the grease G between the bush 30 and the pin 27 flows out due to the deterioration of the sealing device 28 as described above, the resin 32 impregnated in the bush 30 is separated from the bush inner peripheral surface 30A and the pin outer periphery. The fluidity is enhanced by frictional heat with the surface 27A and the fluid flows out of the pores 31 into the sliding surface, so that the sliding surface can be ensured with lubricity. Therefore, it is possible to suppress the generation of abnormal noise due to the sliding between the bush 30 and the pin 27 and reduce the wear on the sliding surface between the bush 30 and the pin 27. As a result, the durability and life of the crawler belt coupling device 24 can be improved.

  On the other hand, during traveling of the hydraulic excavator, the driving force of the traveling hydraulic motor 15 is transmitted to the crawler belt 17 while the driving wheel (sprocket) 14 and the outer peripheral surface 30B of the bush 30 engaged with the driving wheel 14 slide. The

  At this time, for example, in the crawler belt coupling device having the structure as described above, grease lubrication is performed for sliding between the bush 30 and the pin 27. However, the drive wheel 14 and the bushing outer peripheral surface 30B are in contact with each other. Since no consideration was given to sliding, the sliding surfaces of the drive wheel 14 and the bush 30 were in a sliding state in a dry environment. Therefore, since the drive wheel 14 and the bush 30 made of a metal material slide directly in a dry environment, there is a risk of generating abnormal noise and promoting wear.

  On the other hand, in the crawler belt coupling device 24 of the present embodiment, the bush 30 is made of a sintered alloy having a porosity of 2 to 20% as described above, and has self-lubricating characteristics in the pores 31. Since the resin 32 is impregnated, even when the drive wheel 14 and the bushing outer peripheral surface 30B slide, the impregnated resin 32 flows out to the sliding surface, thereby ensuring lubricity. Accordingly, it is possible to suppress the generation of noise due to the sliding between the driving wheel 14 and the bush 30 and reduce the wear on the sliding surface between the driving wheel 14 and the bush 30. As a result, the durability and life of the crawler belt coupling device 24 can be improved.

  Furthermore, according to the crawler belt coupling device 24 of the present embodiment, as described above, the wear on the sliding surface between the bush 30 and the pin 27 can be reduced. As a result, the gap between the bush inner peripheral surface 30A and the pin outer peripheral surface 27A is reduced. It is possible to make the clearance C appropriate. This effect will be described below using a comparative example.

  That is, as described above, when the sealing device 28 is deteriorated and the sealing function is lowered, the enclosed grease G flows out to the outside, and the bush 30 and the pin 27 slide directly in a dry environment. There is a risk of promoting wear.

  Here, in order to reduce abnormal wear when the grease G flows out in this manner, for example, a structure in which the clearance C between the bush 30 and the pin 27 is set excessively in advance (Comparative Example 1) is conceivable. However, in the case of this comparative example 1, there is a possibility that abnormal noise may be generated before the seal device 28 deteriorates due to a rattling noise generated between the bush 30 and the pin 27. As a result, a large load acts on the bush 30 and the bush 30 may be damaged.

  According to the present embodiment, since the lubricity between the bush 30 and the pin 27 can be maintained even when the grease G flows out as described above, the bush as in the first comparative example described above. It is not necessary to set the clearance C between 30 and the pin 27 excessively. Thereby, it is possible to set the clearance C to an appropriate value within the range of 0.05 to 0.2 mm. Therefore, it is possible to prevent the abnormal sound such as rattling noise and the breakage of the bush 30 that may occur in the case of Comparative Example 1 in which the clearance C is increased.

  Next, another embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, the crawler belt coupling device of the present invention is applied to a small hydraulic excavator (so-called mini excavator) having an operating mass of several tons.

FIG. 7 is a side view showing the entire structure of a hydraulic excavator provided with another embodiment of the crawler belt coupling device of the present invention.
7, 35 is a traveling body, 36 is a revolving body mounted on the traveling body 35 so as to be able to swivel, 37 is a cab provided on the revolving body 36, and 38 is a front side of the revolving body 36 (see FIG. The hydraulic excavator according to the present embodiment is roughly constituted by the traveling body 35, the swivel body 36, the cab 37, and the work apparatus 38.

  39 is a substantially H-shaped track frame in plan view, 40 is a side frame provided on both the left and right sides of the track frame 39, and 41 is near the rear end (right end in FIG. 7) of the left and right side frames 40. Drive wheels (sprockets) supported rotatably, 42 is a hydraulic motor for driving the drive wheels 41, and 43 is rotatable in the vicinity of the front end (left end in FIG. 7) of the side frames 40 on both the left and right sides. A driven wheel (idler) 44 is supported by a crawler belt provided by winding a drive wheel 41 and a driven wheel 43 on both the left and right sides, and the driven wheel 43 is connected to the drive wheel 41 via the crawler belt 44. It is rotated by the driving force. Reference numeral 45 denotes an upper roller provided on the upper side of the left and right side frames 40 to guide the crawler belts 44, and a plurality of lower rollers 46 provided on the lower sides of the left and right side frames 40 to guide the crawler belts 44. Laura.

FIG. 8 is a cross-sectional view showing the structure of the crawler belt coupling device of the present embodiment.
In FIG. 8, 50 is a plurality of shoes constituting the ground contact surface of the crawler belt 44, 51 is a crawler belt coupling device that rotatably couples the plurality of shoes 50, 52 is the inside of the shoe 23 (upper side in FIG. 8). A pair of track links fixed to the track link, 53 is an outer link portion formed on one side in the longitudinal direction of the track link 52, 54 is an inner link portion formed on the other side in the longitudinal direction of the track link 52, and 55 is at both ends thereof. A bush 56, which is press-fitted into the bush insertion holes 54A, 54A of the inner link portions 54, 54, is slidably inserted into the bush 55, and both end sides thereof are outer link portions 53, 53. These pins are inserted into the pin insertion holes 53A, 53A in a press-fitted state. The crawler belt coupling device 51 includes a pair of track links 52, 52, a pin 56, and a bush 55. The bush 55 is made of 3 to 20 wt. %, And the porosity of the sintered alloy is, for example, about 10%. The pores in the sintered alloy are impregnated with a resin (or a wax) having self-lubricating properties. Note that the porosity of the bush 55 is preferably about 2 to 20%.

  In the crawler belt coupling device 51 of the present embodiment, the difference from the above-described one embodiment is that the bush 55 and the pin 56 slide in a dry environment, and therefore no seal device is provided. Side surfaces 55 </ b> C at both ends of 55 are provided so as to directly contact inner side surfaces 53 </ b> B located on the inner side of the outer link portion 53 of the track link 52 (in the horizontal direction center side in FIG. 8). The bush side surface 55C and the outer link portion inner surface 53B are slidable. Since the configuration other than this is the same as that of the above-described embodiment, the description thereof is omitted.

According to the present embodiment configured as described above, the following operational effects can be obtained. This effect will be described using a comparative example.
That is, in the small hydraulic excavator as in the present embodiment, since the vehicle body weight is relatively light, the surface pressure of the sliding surface between the bush 55 and the pin 56 is also small. In such a configuration, a structure (Comparative Example 2) in which the bush 55 and the pin 56 are slid in a dry environment without providing a sealing device in the crawler belt coupling device is conceivable.

  However, in the structure as in Comparative Example 2 above, since the metal material slides directly in a dry environment even though the surface pressure of the sliding surface between the bush 55 and the pin 56 is small, an abnormal noise is generated. There is a risk of promoting generation and wear. Further, the sliding between the bush 55 and the drive wheel 41 and the sliding between the bush 55 and the outer link portion 53 of the track link 52 are also in a sliding state in a dry environment, so that abnormal noise is generated and wear is accelerated. There is a risk of inviting.

  On the other hand, according to the present embodiment, the resin impregnated in the bushing 55 is improved in fluidity by frictional heat and flows out from the pores to the sliding surface in the same manner as in the above-described one embodiment. The lubricity of the moving surface can be ensured. That is, in addition to the sliding surface between the bush inner peripheral surface 55A and the pin outer peripheral surface 56A and the sliding surface between the bush outer peripheral surface 55B and the drive wheel 41, the bush side surfaces 55C and the inner side surface 53B of the outer link portion 53 It is possible to ensure lubricity also on the sliding surface. Accordingly, it is possible to suppress the generation of noise due to sliding between the bush 55 and the pin 56, the bush 55 and the drive wheel 41, and the bush 55 and the track link 52, and reduce wear on the sliding surfaces. As a result, the durability and life of the crawler belt coupling device 51 can be improved. Further, it is possible to obtain an effect of preventing noise such as rattling noise and breakage of the bush 55 due to proper clearance.

  In the above-described embodiment and other embodiments of the present invention, the entire bushes 30 and 55 are made of a sintered alloy. However, the present invention is not limited to this. That is, the bushes 30 and 55 may be made of, for example, boron steel, carbon steel, alloy tool steel, or the like in the same manner as the pins 27 and 56, and a sintered alloy may be formed only on the sliding surface (that is, the surface layer portion). . By setting it as such a structure, the mechanical strength of the bushes 30 and 55 can be improved.

  In the embodiment described above, a sintered alloy was not formed for the pins 27 and 56. However, the present invention is not limited to this, and the outer peripheral surfaces 27A and 56A of the pins 27 and 56 are impregnated with resin or the like. A sintered alloy may be formed. Thereby, the lubricity in the sliding surface of a bush and a pin can further be improved.

Furthermore, in the embodiment described above, the bushes 30 and 55 are not particularly subjected to the surface treatment. However, the present invention is not limited to this, and the sliding surfaces of the bushes 30 and 55 are, for example, carburized, carbonitrided, or laser. The surface treatment may be performed by methods such as quenching and ion plating. Furthermore, the pins 27 and 56 may be subjected to surface treatment.
As a result, the wear resistance of the sliding surface can be improved. As a result, even if foreign matter such as earth and sand enters between the bush and the pin from the outside, the bush and the pin are caused by the foreign matter. Can be prevented from wearing out at an early stage.

Further, in the embodiment described above, the pores in the sintered alloy constituting the bushes 30 and 55 are impregnated with resin (or wax) having self-lubricating properties. For example, you may make it impregnate the grease type lubricant etc. which added the extreme pressure material.
Thereby, for example, when seizure is likely to occur on the sliding surface, the extreme pressure material reacts with the metal surface of the sintered alloy due to the high temperature state so that the reaction product covers the metal surface. can do. In general, this reaction product has lubricity, so that seizure can be prevented.

Furthermore, the pores in the sintered alloy constituting the bushes 30 and 55 may be impregnated with any of molybdenum disulfide, lead, copper, and a mixture thereof.
That is, for example, a molybdenum compound such as molybdenum disulfide is a solid having a layered crystal structure, and is generally used as a solid lubricant because it has a property that a bonding force between layers is weak and resistance to slip deformation is small.
Therefore, by impregnating the sintered alloy with a solid lubricant such as molybdenum disulfide, lead, copper, or a mixture thereof together with the lubricating oil, for example, these solid lubricants can be applied from the pores of the sintered alloy to the sliding surface during sliding. The agent can flow out together with the lubricating oil, and the lubricity on the sliding surface can be further improved.

It is a side view showing the whole structure of a hydraulic excavator provided with one embodiment of a crawler belt connecting device of the present invention. 1 is a partially enlarged perspective view showing a detailed structure of a crawler belt of a hydraulic excavator provided with an embodiment of a crawler belt coupling device of the present invention. It is a top view which shows the detailed structure of the crawler belt of the hydraulic excavator provided with one Embodiment of the crawler belt coupling apparatus of this invention in a partial cross section. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 2 showing the structure of an embodiment of the crawler belt coupling device of the present invention. It is sectional drawing by the VV cross section in FIG. 4 which shows the cross-section of the bush and the pin which comprise one Embodiment of the crawler belt coupling apparatus of this invention. FIG. 6 is an enlarged view of a portion A in FIG. 5 illustrating a state of a sliding surface between a bush and a pin constituting an embodiment of the crawler belt coupling device of the present invention. It is a side view showing the whole structure of the hydraulic excavator provided with other embodiment of the crawler belt connecting device of the present invention. It is a cross-sectional view showing the structure of another embodiment of the crawler belt coupling device of the present invention.

Explanation of symbols

24 crawler belt connecting device 25 track link 26 outer link portion 27 pin 27A pin outer peripheral surface 29 inner link portion 30 bush 30A bush inner peripheral surface 30B bush outer peripheral surface 51 crawler belt connecting device 52 track link 53 outer link portion 54 inner link portion 56 pin 56A Pin outer peripheral surface 55 Bush 55A Bush inner peripheral surface 55B Bush outer peripheral surface

Claims (10)

  An outer link portion is formed on one side in the longitudinal direction and an inner link portion is formed on the other side in the longitudinal direction, and a pair of track links connected endlessly with each other, and the inner link portions of the pair of track links are connected. And a pin that is inserted into the bush and has both ends fitted into the outer link portion and connected between the outer link portions, and an inner peripheral surface of the bush and A crawler belt coupling device, wherein a sintered alloy having a porosity of 2 to 20% is provided on at least one of the outer peripheral surfaces of the pins.   An outer link portion is formed on one side in the longitudinal direction and an inner link portion is formed on the other side in the longitudinal direction, and a pair of track links connected endlessly with each other, and the inner link portions of the pair of track links are connected. And a pin that is inserted into the bush and has both ends fitted into the outer link portion and connected between the outer link portions, and has a pore in the outer peripheral surface of the bush. A crawler belt coupling device comprising a sintered alloy having a rate of 2 to 20%.   3. The crawler belt coupling apparatus according to claim 1 or 2, wherein the sintered alloy is impregnated with wax or a resin having self-lubricating characteristics.   3. The crawler belt coupling apparatus according to claim 1 or 2, wherein the sintered alloy is impregnated with a grease-based lubricant added with an extreme pressure material based on high viscosity oil.   3. The crawler belt coupling apparatus according to claim 1, wherein the sintered alloy is impregnated with any of molybdenum disulfide, lead, copper, and a mixture thereof.   3. The crawler belt coupling apparatus according to claim 1, wherein the sintered alloy is surface-treated by any one of carburizing, carbonitriding, laser hardening, and ion plating.   3. The crawler belt coupling apparatus according to claim 1, wherein a clearance between the inner peripheral surface of the bush and the outer peripheral surface of the pin is 0.05 to 0.2 mm.   3. The crawler belt coupling apparatus according to claim 1, wherein the sintered alloy contains 3 to 20 wt% of copper.   A pair of track links that are endlessly connected to each other are provided so as to connect between inner link portions formed on one side in the longitudinal direction, and a porosity of 2 to 20% is provided on at least one of the inner peripheral surface and the outer peripheral surface. A crawler belt connecting bush characterized by comprising a sintered alloy of   The outer link portions are connected by being fitted into outer link portions formed on one side in the longitudinal direction of a pair of track links which are inserted into the bush and both ends thereof are connected endlessly to each other. A crawler belt connecting pin, characterized in that a sintered alloy having a porosity of 2 to 20% is provided on the outer peripheral surface.

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