JPH09228405A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to enhance dramatically the wear resistance of an outside bush and an inside bush and compensate for a smooth turning of a mating member with a socket material for a long period. SOLUTION: Each of outside bushes 16 is entirely formed with sintered and oil impregnated alloy while each surface hardening layer 20 is formed on the whole surfaces of each of inside bushes 17 including each of sliding surfaces 18C and 19A and each seal surface 19C, which makes it possible to upgrade the hardness of the sliding surfaces 18C and 19C with each surface hardening layer 20. This constriction makes it possible to hold a space between each of the sliding surface 16A and 16B and each of the sliding surface 18C and 18A in a lubricated state all that time by the application of a lubricant from each outside bush 16 and minimize definitely the sliding resistance which acts on a space between each of the sliding surface 16A and 16B and each of the sliding surfaces 18C and 19A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device which is preferably used for a pin connecting portion of a working device mounted on a construction machine such as a hydraulic excavator.

[0002]

2. Description of the Related Art A working device mounted on a construction machine such as a hydraulic excavator is provided with a plurality of bearing devices for rotatably supporting a boom, an arm, a bucket, and the like via a connecting pin.

A conventional bearing device of this type is disclosed in, for example, Japanese Utility Model Laid-Open No. 59-139551.
It is disclosed that the hydraulic excavator is applied between a tip of an arm and a bucket and is applied to a pin coupling portion that rotatably connects the bucket to the arm.

This bearing device includes an arm side boss portion as a boss member provided on the tip side of an arm, a pair of left and right bucket side bracket portions as a counterpart member provided on a bucket, and an arm side boss. Pin for connecting the bracket portion and the bracket portion on the bucket side relative to each other, and a pair of left and right bushes provided on both axial ends of the arm side boss portion and provided between the connecting pin and the boss portion. And so on. Then, the bucket disposed on the tip side of the arm is rotated about the connecting pin with respect to the arm by operating a bucket cylinder connected to the bucket via a link mechanism, so that excavation work or the like can be performed. It has become.

Here, the pair of bushes forming a part of the bearing device include an inner bush inserted into both axial ends of the connecting pin, and an outer peripheral side press-fitted into both axial end portions of the arm side boss portion. The outer bush is slidably fitted to the outer circumference of the inner bush.
An enlarged collar portion is provided which is fixed to the bracket portion on the bucket side via a knock pin. Then, between the axially outer end surface of the outer bush and the flange portion of the inner bush, a seal member for preventing dirt and sand from entering the sliding surface of the inner bush and the outer bush through a gap between the two. Is provided. Further, a spacer is provided between the inner bush and the outer bush so as to be located radially inward of the seal member.

[0006]

By the way, in the above-mentioned conventional pin coupling device, in order to prevent intrusion of earth and sand or the like between the inner bush and the outer bush during excavation work by the bucket, they slide against each other. It is necessary to reduce the axial gap formed between the inner bush and the outer bush.

Further, in the above bearing device, in order to provide the seal member in the gap between the collar portion of the inner bush and the end edge portion of the outer bush, the collar portion of the inner bush and the end surface of the outer bush are respectively sealed. Since it is necessary to form the seal receiving portion for holding the member, there is a problem that the mounting structure of the seal member is complicated and the manufacturing cost is increased.

Further, since the spacer disposed between the collar portion of the inner bush and the end surface of the outer bush has a small axial dimension (wall thickness), it receives a load in the axial direction during excavation work and relatively early. There is a problem that smooth rotation of the bucket with respect to the arm cannot be compensated for a long period of time due to wear and backlash on the sliding surface between the flange portion of the inner bush and the outer bush.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to reliably prevent dust and the like from entering the sliding portion between the boss member and the counterpart member, and to greatly simplify the structure. In addition, it is possible to significantly improve the wear resistance of the outer bush and the inner bush, and to provide a bearing device capable of compensating the smooth rotation of the counterpart member with respect to the boss member for a long period of time. To aim.

[0010]

In order to solve the above problems, the present invention provides a boss member having a bush fitting hole formed in the axial direction, and a connecting pin for rotatably connecting the boss member to a mating member. It is applied to bearing devices consisting of.

The feature of the configuration adopted by the invention of claim 1 is that the bearing is composed of a boss member having a bush fitting hole formed in the axial direction, and a connecting pin for rotatably connecting the boss member to a mating member. In the device, an outer bush formed in a cylindrical shape from a sintered oil-impregnated alloy and fitted in the bush fitting hole of the boss member, and an outer peripheral side slidably fitted in the outer bush, and an inner peripheral side An inner bush formed with a pin insertion hole for the connecting pin, and formed on the outer peripheral side of the inner bush so as to be in sliding contact with the end surface of the outer bush,
A collar portion that forms a seal accommodating space with the boss member, and a seal that is disposed in the seal accommodating space between the collar portion and the boss member and that seals between the outer bush and the inner bush. And a member, the inner bush,
The hardened layer is formed at least on the sliding surface side with the outer bush.

With this structure, the entire outer bush can be formed of the sintered oil-impregnated alloy, and the sliding surface of the inner bush with respect to the outer bush can be formed as a surface-hardened layer. Wearability can be reliably enhanced. Then, the lubricating oil from the outer bush as the sintered oil-impregnated alloy can be supplied between the sliding surfaces of the outer bush and the inner bush, and the sliding surfaces can be constantly kept in a lubricated state. Further, it is possible to reliably prevent dust and the like from entering between the sliding surfaces from the outside by the seal member arranged in the seal accommodating space.

Further, the feature of the constitution adopted by the invention of claim 2 is that the outer bush is fitted in the bush fitting hole of the boss member, and the outer peripheral side is slidably fitted in the outer bush. Then, an inner bush formed with a pin insertion hole for the connecting pin on the inner peripheral side and an inner bush formed on the outer peripheral side of the inner bush so as to be in sliding contact with the end surface of the outer bush, and a seal is formed between the inner bush and the boss member. A collar part that forms a storage space,
A seal member that is disposed in a seal accommodating space between the collar portion and the boss member and seals between the outer bush and the inner bush, among the surface of the inner bush and the surface of the outer bush. The hardened layer is formed at least on the sliding surface side between the outer bush and the inner bush, and the lubricant is supplied to the sliding surface.

Thus, the sliding surface between the outer bush and the inner bush can be formed as a surface hardened layer, and when the mating member is rotated with respect to the boss member, the sliding surface on which the surface hardened layer is formed is formed. The wear resistance of can be reliably increased. Then, the lubricant supplied between the sliding surfaces of the inner bush and the outer bush can surely keep the sliding surfaces in a lubricated state, and surely reduce the sliding resistance acting between the sliding surfaces. You can

Furthermore, the feature of the structure adopted by the invention of claim 3 is that the outer bush formed in a tubular shape from a copper alloy and fitted in the bush fitting hole of the boss member and the outer peripheral side are Formed on the outer peripheral side of the inner bush so that the inner bush is slidably fitted in the outer bush and the pin insertion hole for the connecting pin is formed on the inner peripheral side, and the end surface of the outer bush is slidably contacted. And a flange portion that forms a seal accommodating space between the boss member and the seal accommodating space between the collar portion and the boss member, and seals between the outer bush and the inner bush. A sealing member, and a surface hardened layer is formed on the inner bush at least on the sliding surface side with the outer bush, and the outer bush is provided with a solid lubricant on the sliding surface side with the inner bush. Especially.

As a result, the entire outer bush can be formed of a copper alloy, and the sliding surface of the inner bush with respect to the outer bush can be formed as a surface hardened layer.
The wear resistance of the outer and inner bushes can be reliably increased. The sliding resistance acting between the sliding surfaces of the outer bush and the inner bush can be reliably reduced by the solid lubricant provided on the outer bush.

Still further, the feature of the structure adopted by the invention of claim 4 is that an outer bush is formed by forming a surface hardened layer on at least the inner peripheral surface side and fitted in the bush fitting hole of the boss member. , The outer bushing is slidably fitted in the outer bushing, and the inner bushing is formed with the inner bushing in which the pin insertion hole for the connecting pin is formed on the inner circumferential side, and the inner bushing so as to slidably contact the end surface of the outer bushing. A flange portion that is formed on the outer peripheral side and forms a seal accommodating space with the boss member, and is arranged in the seal accommodating space between the flange portion and the boss member, and has the outer bush and the inner bush. The inner bush is formed of a copper-based alloy into a tubular shape, and the inner bush is provided with a solid lubricant on the sliding surface side with the outer bush.

As a result, the entire inner bush can be formed from a copper alloy, and the sliding surface of the outer bush with respect to the inner bush can be formed as a surface-hardened layer, so that the wear resistance of the outer and inner bushes can be reliably increased. . The sliding resistance acting between the sliding surfaces of the outer bush and the inner bush can be reliably reduced by the solid lubricant provided on the inner bush.

On the other hand, in the invention of claim 5, the surface hardened layer is formed by carburizing. This makes it possible to easily form a surface-hardened layer by carburizing on the sliding surface of the outer bush or the inner bush.

Further, in the invention of claim 6, the surface hardened layer is formed by a nitriding treatment. This makes it possible to easily form a surface-hardened layer by nitriding treatment on the sliding surface of the outer bush or the inner bush.

Further, according to the invention of claim 7, another seal member is provided between the inner peripheral side of the inner bush and the outer peripheral surface of the connecting pin. This makes it possible to reliably prevent dust from entering from the outside between the pin insertion hole of the inner bush and the connecting pin by the other sealing member.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 4 show a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a hydraulic excavator to which a bearing device according to the present invention is applied, and a working device 3 for excavating work is provided on the upper swing body 2 of the hydraulic excavator 1 so as to be able to move up and down. Has been done.

In the working device 3, the boom 4 pin-connected to the upper swing body 2, the arm 5 as a support member pin-connected to the tip end side of the boom 4, and the pin 5 attached to the tip end side of the arm 5. A boom cylinder 7, an arm cylinder 8, a bucket cylinder 9 and a boom cylinder 7, which are connected to each other via a pin connecting portion, are generally configured to include a bucket 6 and the like serving as a rotating member. The link 10 or the like is operated to perform a rotating operation. Then, each of these pin coupling portions is equipped with the bearing device of this embodiment, and, for example, the arm 5 and the bucket 6 are coupled so as to be relatively rotatable via the bearing device shown in FIGS. 2 and 3. Has been done.

In FIGS. 2 and 3, 11 is an arm 5.
2 shows an arm boss as a boss member provided on the tip side of the arm boss 11. A through hole 12 is formed in the axial direction of the arm boss 11. The axially opposite end sides of the through holes 12 become large-diameter bush fitting holes 13, 13 into which outer bushes 16 described later are fitted, and between the bush fitting holes 13 and the through holes 12. Are formed with annular projections 14 and 14 that project inward in the radial direction and have a smaller diameter than the bush fitting hole 13.

Numerals 15 and 15 are a pair of brackets as projecting members provided outside the bucket 6 so as to sandwich the arm boss 11 of the arm 5, and a connecting pin 21 described later is inserted into each bracket 15. Pin through holes 15A, 15A are formed. Then, the inner end surface of each bracket 15 has contact portions 15B, 15B for contacting each collar portion 19 described below with the portion located around the pin through hole 15A.
It has become.

Reference numerals 16 and 16 denote a pair of outer bushes located at both axial ends of the arm boss 11 and fitted in the bush fitting holes 13, respectively.
Further, as shown in FIG. 3, it is formed as a cylindrical body from a sintered oil-impregnated alloy, and is press-fitted and fitted into the bush fitting hole 13 in a state where its axially inner end surface is in contact with each annular protrusion 14.

Here, the inner peripheral surface of each outer bush 16 serves as a sliding surface 16A with respect to a sliding surface 18C of an inner bush 17 which will be described later, and the radially inner portion of the axially outer end surface thereof is each collar portion 19 which will be described later. Each sliding surface 16B with respect to each sliding surface 19A.

The axial dimension of the outer bush 16 is set to be shorter than the axial dimension (depth) of the bush fitting hole 13 formed in the arm boss 11, as shown in FIG. A flange portion 19 of each inner bush 17, which will be described later, is provided between the axially outer end surface of the outer bush 16 and each bracket 15.

Then, each outer bush 16 applies the lubricating oil as a lubricant impregnated in the inside thereof to each of the sliding surfaces 16A,
16B and the respective sliding surfaces 18C and 19A are constantly supplied so that the sliding surfaces 16A and 16B and the sliding surfaces 18
C and 19A are always kept in a lubricated state.

Reference numerals 17 and 17 denote a pair of inner bushes slidably fitted to the inner peripheral side of each outer bush 16, and each inner bush 17 is formed as shown in FIGS. 2 to 4. The inner bush 17 is integrally formed from a steel material (chromium molybdenum steel such as SCM415 or SCM420) into a stepped tubular body, and has a cylindrical portion 18 in which a pin insertion hole 18A is formed in the axial direction. Cylindrical part 1
8 is provided with a short cylindrical flange 19 projecting radially outward from a position on the outer side in the axial direction. A mounting groove 18B is formed on the outer peripheral side of the cylindrical portion 18 at a position facing the annular protrusion 14 of the arm boss 11 to which each stopper 24 described later is mounted.

Here, the outer peripheral surface of the cylindrical portion 18 is a sliding surface 18C with respect to the sliding surface 16A of the outer bush 16.
Therefore, the radial load from the connecting pin 21 integrated with the bucket 6 via each bracket 15 is applied to each sliding surface 1
It is configured to be accepted between 6A and 18C.

Further, the collar portion 19 has an axially inner end surface serving as a sliding surface 19A with respect to the sliding surface 16B of the outer bush 16, and an axial outer end surface thereof having an abutting surface 15B of the bracket 15.
Is a contact surface 19B with respect to. As a result, the thrust load from each bracket 15 integrated with the bucket 6 is received between the sliding surfaces 16B and 19A. Further, the outer peripheral surface of each of the collar portions 19 serves as each sealing surface 19C for each sealing member 23 described later.

Reference numerals 20 and 20 denote surface-hardened layers, and each surface-hardened layer 20 is formed as a hardened layer on the surface of the inner bush 17 by carburizing the inner bush 17. Here, the surface-hardened layer 20 covers the entire inner bush 17 including the inner peripheral surface of the pin insertion hole 18A, the sliding surfaces 18C and 19A, the contact surface 19B, and the sealing surface 19C. Formed, each of these pin insertion holes 18
The hardness of the inner peripheral surface of A, the sliding surfaces 18C and 19A, the contact surface 19B, and the sealing surfaces 19C is reliably increased.

Reference numeral 21 denotes the arm boss 11 and each bracket 15
The connecting pins are connected to each other, and both ends of the connecting pin 21 are inserted into the pin through holes 15A of each bracket 15, and the bucket 6 is rotatably connected to the arm 5.

The connecting pin 21 has pin insertion holes 18A for the inner bushes 17 on both sides located in the through hole 12.
It is inserted in the state of being pressed into. Also, the connecting pin 2
1, the large-diameter head 21A side provided on one axial side thereof is attached to one bracket 15, and the other axial side is attached to the other bracket 15 via a fixing ring 25 and a retaining pin 26 described later. It is attached to the pair of brackets 15 and is held in a state in which the brackets 15 are not pulled out and prevented from rotating.

22 and 22 are located between each bracket 15 and each outer bush 16, and are annular seal accommodating spaces formed between each bush fitting hole 13 of the arm boss 11 and each collar 19. 23 and 23 are the seal accommodation spaces 22
A sealing member disposed inside the sealing member 23 is shown.
Is an annular outer shell 23A made of a metal material press-fitted into each bush fitting hole 13, and a lip seal 23B fixed in the outer shell 23A via a metal holder (not shown) or the like.
It is composed of

Here, each lip seal 23B is formed in an annular shape from an elastic material such as urethane rubber, and its tip side (inner peripheral edge) is slidably contacted with the spring surface so as to press it against the sealing surface 19C of each collar portion 19. , Sliding surfaces 16A and 16B of each outer bush 16 and sliding surfaces 18 of each inner bush 17
It prevents dirt and sand from entering the sliding surface with C and 19A. Then, the lip seal 23B of each seal member 23
When the inner bush 17 rotates together with the connecting pin 21, a large frictional resistance acts on each flange portion 19 of the inner bush 17.

Reference numerals 24 and 24 denote stoppers composed of retaining rings and the like. The stoppers 24 are mounted on the inner peripheral side in the respective mounting grooves 18B of the inner bushes 17 and on the outer peripheral side.
It projects radially from the cylindrical portion 18 of No. 7. The stoppers 24 prevent axial displacement of the inner bushes 17 with respect to the outer bushes 16 when the bearing device is assembled.

Reference numeral 25 denotes a fixing ring fixed to the outer peripheral side of each pin through hole 15A on the outer end surface of each bracket 15, and the other end side of the connecting pin 21 is fitted to the inner peripheral side of the fixing ring 25. Is inserted in. Then, the retaining pin 26 is radially passed through the other end side of the connecting pin 21 and the fixed ring 25 to prevent the connecting pin 21 from rotating with respect to each bracket 15 and hold the retaining pin in a retaining state.

The bearing device according to the present embodiment has the above-mentioned structure, and the sliding surface 18C of each inner bush 17 is
19A slides on the sliding surfaces 16A and 16B of the outer bushes 16 to rotate the inner bushes 17 attached to the connecting pins 21 relative to the outer bushes 16 attached to the arm boss 11. Arm 5
The bucket 6 which is pin-coupled via the bearing device at the tip end side of is rotated.

Here, when the bucket 6 is rotated, a large radial load from the bucket 6 acts between the sliding surfaces 16A and 18C via the connecting pin 21 and the sliding surfaces 16B and 18C. During 19A, a large thrust load from the bucket 6 acts via each bracket 15. Further, a large frictional resistance acts on the seal surface 19C of each flange 19 from the lip seal 23B of the seal member 23.

However, in this embodiment, each outer bush 1
6 is formed from a sintered oil-impregnated alloy, and each surface hardening layer 20 is provided with each sliding surface 18C, 19A and each sealing surface 19
Since it is formed over the entire surface of each inner bush 17 including C, the hardness of the sliding surfaces 16A and 16B can be reliably increased by a sintered alloy, and the sliding surface 18
The hardness of C and 19A can be surely increased by the surface hardening layers 20.

Further, the lubricating oil from each outer bush 16 can constantly maintain a lubricating state between each of the sliding surfaces 16A, 16B and each of the sliding surfaces 18C, 19A. , 16B and the sliding surfaces 18C, 19A can be reliably reduced in sliding resistance.
Then, in this case, grease or lubricating oil (lubricant) of the same type as the lubricating oil is replenished between the through hole 12 of the arm boss 11 and the connecting pin 21 from the outside, so that this lubricating oil is slid. Moving surfaces 16A, 16B and sliding surfaces 1
8C, 19A can be continuously replenished, and the sliding resistance acting between the sliding surfaces 16A, 16B and the sliding surfaces 18C, 19A can be reliably reduced for a long period of time. it can.

Further, each collar portion 19 (each inner bush 1
The seal surface 19C of 7) can be formed by each surface hardening layer 20, and the seal surface 19C is the lip seal 2 of each seal member 23 disposed in each seal accommodation space 22.
It is possible to effectively reduce abrasion, damage, etc. due to the sliding resistance generated with the 3B.

Therefore, in this embodiment, when the bucket 6 is rotated, the sliding surfaces 18C and 19A of the inner bushes 17 formed by the respective surface hardened layers 20 and the outer bushes 16 formed by the sintered oil-impregnated alloy. Sliding surfaces 16A, 16
B and B can be slid on each other via the lubricating oil from each of the outer bushes 16, so that the sliding surfaces 16A, 16
It is possible to significantly reduce wear, damage, etc. on B, 18C, 19A, and reliably prevent rattling in the thrust direction and the radial direction between each outer bush 16 and each inner bush 17. The smooth rotation of the bucket 6 with respect to the arm 5 can be compensated for a long period of time.

Further, the lip seal 2 of each seal member 23
3B and the sealing surface 19C of each flange portion 19 on which each surface hardened layer 20 is formed can be reliably maintained in a sealed state for a long period of time, and the pin insertion hole 1 of each inner bush 17
It is possible to reliably prevent foreign matter such as earth and sand from entering between the 8A and the connecting pin 21 from the outside, and the sliding surface 1
It is possible to more reliably prevent the 6A, 16B, 18C and 19A from being worn or damaged.

Further, since the inner peripheral surface (pin insertion hole 18A) of each inner bush 17 can be formed by each surface hardened layer 20, wear generated on the inner peripheral surface of each inner bush 17
Damage and the like can be effectively prevented, rattling of the connecting pin 21 with respect to each inner bush 17 can be prevented, and the contact surface 19B of each collar portion 19 formed by the surface hardened layer 20 can be attached to each bracket 15. By contacting the contact surfaces 15B of the buckets 6 with each other, it is possible to effectively prevent wear and damage of the respective contact surfaces 19B, which also enables smooth rotation of the bucket 6 with respect to the arm 5 for a long period of time. Can be compensated over.

Furthermore, each seal member 23 can be easily arranged in each seal accommodating space 22 formed between each bush fitting hole 13 of the arm boss 11 and each collar portion 19, and The mounting structure of the seal member 23 can be simplified,
The manufacturing cost and the like of the bearing device can be surely reduced.

On the other hand, since the surface-hardened layers 20 are formed on the surface of each inner bush 17 by carburizing, the surface-hardened layers 20 can be easily formed, and the manufacturing cost of the surface-hardened layers 20 can be reduced. It can be significantly reduced.

Next, FIGS. 5 and 6 show a second embodiment of the present invention. The feature of this embodiment is that the outer bush and the inner bush are respectively made of a metal material, and the entire surface and the inner side of the outer bush are formed. Each of the hardened layers is formed on the entire surface of the bush, and an oil reservoir for containing grease is formed between the connecting pin and the arm boss. In this embodiment, the same reference numerals are given to the same components as those in the first embodiment, and the description thereof will be omitted.

In the figure, reference numerals 31 and 31 denote outer bushes arranged in the bush fitting holes 13 of the arm boss 11 in place of the outer bushes 16 described in the first embodiment. The bush 31 has sliding surfaces 31A and 31B similar to the outer bushes 16, but the outer bushes 31 are made of steel material (for example, SCM435, SCM440, etc.) as shown in FIGS. A chrome molybdenum steel), etc., to form a tubular body, and a surface hardened layer 35 described later is formed over the entire surface of the tubular body.

Reference numerals 32 and 32 denote inner bushes slidably provided in the sliding surfaces 31B of the outer bushes 31 instead of the inner bushes 17 described in the first embodiment. The bush 32 includes a cylindrical portion 33 and a flange portion 34, similar to the inner bushes 17 described above. The cylindrical portion 33 has a pin insertion hole 33A, a mounting groove 33B and a sliding surface 33C, and the collar portion 34 has a sliding surface 34A, an abutting surface 34B and a sealing surface 34C.

However, each inner bush 32 is formed of a steel material (for example, chrome molybdenum steel made of SCM435, SCM440, etc.) or the like as shown in FIG. 5, and a surface hardened layer 36 described later is formed on the entire surface thereof. Has been formed.

Reference numerals 35 and 36 denote surface hardened layers respectively provided on the outer bushes 31 and the inner bushes 32. The surface hardened layers 35 and 36 are the first surface hardened layer 2 respectively.
Similar to 0, it is formed as a hardened layer over the entire surface of the outer bush 31 and the inner bush 32.

However, the surface hardened layers 35 and 36 are formed by subjecting the outer bushes 31 and the inner bushes 32 to nitriding treatment, respectively.
Different from 0.

Reference numeral 37 denotes an annular oil reservoir chamber formed between the through hole 12 of the arm boss 11 and the connecting pin 21, and the oil reservoir chamber 37 contains a lubricant such as grease G. The oil reservoir chamber 37 contains the grease G on the surface hardening layer 35 formed on the sliding surfaces 31A and 31B of the outer bushes 31 and the sliding surfaces 33C and 34A of the inner bushes 32.
The grease G is constantly supplied to the surface hardened layer 36 formed in the above.

Thus, also in this embodiment having such a configuration, the sliding surfaces 31A, 31B of the outer bushes 31 and the sliding surfaces 33C, 34A of the inner bushes 32 are provided with the surface hardening layers 35, 36 therebetween. Can be slid on each other and the sliding surfaces 31A, 31B and the sliding surfaces 33C,
The grease G can always be kept in a lubricated state with the grease 34A, and the same operational effects as those of the first embodiment can be obtained.

Particularly in this embodiment, the grease G is housed in the annular oil reservoir 37 formed between the through hole 12 of the arm boss 11 and the connecting pin 21, so that the grease is described in the first embodiment. As described above, it is possible to eliminate the need to form each outer bush 31 from a sintered oil-impregnated alloy or the like, and it is possible to greatly reduce the manufacturing cost of each outer bush 31.

Next, FIG. 7 shows a third embodiment of the present invention. The feature of this embodiment is that the outer bush is formed of a high strength brass as a copper alloy into a cylindrical body, and the outer bush of the outer bush is formed. A plurality of solid lubricants are provided on the inner peripheral surface, and another seal member is provided on the inner peripheral side of the inner bush between the inner bush and the outer peripheral surface of the connecting pin. In this embodiment, the same reference numerals are given to the same components as those in the first embodiment, and the description thereof will be omitted.

In the figure, reference numeral 41 denotes an outer bush (only one is shown) provided in each bush fitting hole 13 of the arm boss 11 in place of each outer bush 16 described in the first embodiment. The outer bushes 41 have sliding surfaces 41A and 41B similar to the outer bushes 16, but the outer bushes 41 are formed of a high strength brass as a copper alloy into a cylindrical body. And its sliding surface 41B
A plurality of solid lubricants 42, 42, ... Made of carbon, copper, a fluorine-based resin material, or the like are embedded in the.

Reference numeral 43 denotes a sliding surface 41 of each outer bush 41 instead of each inner bush 17 described in the first embodiment.
B shows an inner bush slidably provided in B (only one is shown), and each inner bush 43 is provided with a cylindrical portion 44 and a collar portion 45, which are substantially the same as the inner bushes 17. A surface hardened layer 46 similar to the surface hardened layer 20 described in the first embodiment is formed over the entire surface of the cylindrical portion 44 and the surface of the flange portion 45. The cylindrical portion 44 has a pin insertion hole 44A, a mounting groove 44B and a sliding surface 44C, and the collar portion 45 has a sliding surface 45A,
It has a contact surface 45B and a seal surface 45C.

However, in each inner bush 43, an annular groove 44D having a substantially L-shaped cross section toward the radially outer side is formed on the inner peripheral surface of the cylindrical portion 44 located on the contact surface 45B side of each collar portion 45.
Is different from the inner bushes 17 in that they are formed.

Reference numeral 47 denotes an annular seal accommodating space formed between the annular groove 44D of the inner bush 43 and the connecting pin 21, and the seal accommodating space 47 has the seal member described in the first embodiment. Similar to 23, another seal member 48 including an outer shell 48A and a lip seal 48B is provided, and the lip portion of the lip seal 48B is connected to the connecting pin 21.
Is elastically abutted on the outer peripheral surface of the.

Then, the sealing member 48 is provided with a small gap or the like formed between the contact surface 45B of the collar portion 45 and the contact surface 15B of the bracket 15 for dust from the outside, and the like.
This prevents entry into a slight gap between the connecting pin 21 and the inner peripheral surface of the cylindrical portion 44.

Thus, also in this embodiment having such a structure, the sliding surfaces 44C, 45A of the inner bushes 43 formed by the respective surface hardened layers 46 and the outer bushes 41 formed by the high strength brass are formed. Sliding surface 41A, 41B
And can be slid on each other, and the sliding resistance acting between the sliding surfaces 44C and 45A and the sliding surfaces 41A and 41B can be significantly reduced by the solid lubricants 42. It is possible to obtain substantially the same operational effects as those of the first embodiment.

However, in this embodiment, each inner bush 4 is
Since each seal accommodating space 47 is formed between the inner peripheral surface of the cylindrical portion 44 of No. 3 and the connecting pin 21, and each other seal member 48 is disposed in each seal accommodating space 47, the connecting pin 21 and the cylinder are It is possible to reliably prevent dust and the like from entering the slight gap between the inner peripheral surface of the portion 44 and the outside.
This further reliably prevents the outer peripheral surface of the connecting pin 21 and the inner peripheral surface (each surface hardened layer) of the pin insertion hole 44A of each cylindrical portion 44 from being worn or damaged by such dust intrusion. Therefore, rattling and the like between the connecting pin 21 and each inner bush 43 can be significantly reduced.

Next, FIG. 8 shows a fourth embodiment of the present invention. In this embodiment, the same components as those of the second embodiment are designated by the same reference numerals and the description thereof will be omitted. To do. However, the feature of the present embodiment is that the inner bush 51 is formed into a cylindrical body by using high strength brass as a copper alloy, and the sliding surface 52C of the cylindrical portion 52 constituting the inner bush 51 has, for example, carbon or copper. Alternatively, it is configured to embed a plurality of solid lubricants 54, 54, ... Made of a fluorine resin material or the like.

Here, each inner bush 51 has the second bush
The cylindrical portion 5 is the same as each inner bush 32 described in the embodiment.
2 and the collar portion 53. Then, the cylindrical portion 52
Is the pin insertion hole 52A, the mounting groove 52B, and the sliding surface 52C.
The collar portion 53 has a sliding surface 53A, an abutting surface 53B, and a sealing surface 53C.

Thus, also in this embodiment having such a structure, the sliding surfaces 31A, 31B of the outer bushes 31 formed by the respective surface hardened layers 35 and the inner bushes 51 formed by high strength brass are slid. The moving surfaces 52C and 53A can be slid on each other, and the respective sliding surfaces 3
The sliding resistance acting between the 1A, 31B and the sliding surfaces 52C, 53A can be greatly reduced by the respective solid lubricants 54, and substantially the same working effect as that of the first embodiment can be obtained. it can.

In the first and third embodiments,
Although each surface-hardened layer 20 (46) is described as being formed by a carburizing treatment, it may be formed by a nitriding treatment instead.

Further, in the second and fourth embodiments,
Although each surface hardening layer 35 (36) is described as being formed by the nitriding treatment, it may be formed by a carburizing treatment instead.

Further, in the first, second and fourth embodiments, between the pin insertion holes 18A (33A, 52A) of the inner bushes 17 (32, 51) and the connecting pin 21,
A seal accommodation space similar to each seal accommodation space 47 and each other seal member 48 described in the third embodiment, and each other seal member may be provided.

Further, the case where the bearing device is applied to the pin coupling portion between the arm 5 and the bucket 6 of the hydraulic excavator 1 has been described as an example, but the present invention is not limited to this, and the link 10 and the bucket 6 are used. The present invention can be widely applied to other pin coupling parts such as a pin coupling part with and a pin coupling part with the arm 5 and the arm cylinder 8.

[0076]

As described in detail above, according to the invention of claim 1, the seal member is disposed in the seal accommodating space formed between the boss member and the flange portion, and the outer bush is sintered. The inner bush is formed into a tubular shape, and the inner bush has a surface hardened layer at least on the sliding surface side with the outer bush, so that the sliding surface between the outer bush and the inner bush has wear resistance. In addition to being able to surely improve, the lubricating oil from the outer bush can keep the sliding surface between the sliding surfaces in a lubricated state for a long time, and the sliding resistance acting between the sliding surfaces can be surely reduced. it can.

Therefore, when the mating member is rotated relative to the boss member, it is possible to remarkably reduce the occurrence of wear and damage on the sliding surfaces of the inner bush and the outer bush. It is possible to reliably extend the life, etc., and it is possible to reliably prevent rattling in the thrust direction and the radial direction between the outer bush and the inner bush, and to smoothly rotate the mating member relative to the boss member for a long time. Can be compensated over.

Further, the seal member can be easily arranged in the seal accommodating space, the mounting structure of the seal member can be simplified, and the manufacturing cost of the bearing device can be surely reduced.

Further, according to the invention of claim 2, of the surfaces of the inner bush and the outer bush, a surface hardened layer is formed on at least a sliding surface side of the outer bush and the inner bush, and the sliding surface is formed on the sliding surface. Since the lubricant is supplied, the wear resistance of the sliding surface can be surely enhanced by the surface hardened layer. Then, the lubricant supplied between the sliding surfaces of the inner bush and the outer bush can surely keep the sliding surfaces in a lubricated state, effectively reducing the sliding resistance acting between the sliding surfaces. it can.

Therefore, it is possible to save the trouble of regularly supplying the lubricating oil from the outside between the outer bush and the inner bush, and to significantly reduce the burden on the operator during maintenance work of the bearing device. Can be converted.

Further, in the invention of claim 3, the outer bush is formed in a cylindrical shape from a copper alloy, and a surface hardened layer is formed on the inner bush at least on the sliding surface side with the outer bush, and the outer bush is formed. Since the bush is provided with a solid lubricant on the sliding surface side with the inner bush, the wear resistance of the sliding surface can be reliably improved, and the sliding resistance acting between the outer bush and the inner bush is solid. The lubricant can surely reduce the size. This also makes it possible to save the trouble of regularly supplying lubricating oil from the outside between the outer bush and the inner bush, and significantly reduce the burden on the operator during maintenance work of the bearing device. be able to.

Further, in the invention of claim 4, a surface hardened layer is formed on at least the inner peripheral surface side of the outer bush, and the inner bush is formed in a tubular shape from a copper alloy,
Further, since the inner bush is provided with the solid lubricant on the sliding surface side with the outer bush, the wear resistance of the sliding surface can be surely improved, and the sliding action acting between the outer bush and the inner bush is achieved. The dynamic resistance can be reliably reduced by the solid lubricant. This also eliminates the need to regularly supply lubricating oil from the outside between the outer bush and the inner bush, and significantly reduces the burden on the operator during maintenance work on the bearing device. can do.

On the other hand, in the invention of claim 5, all the surfaces of the outer and inner bushes can be easily formed as a surface-hardened layer by carburizing treatment, and the manufacturing cost of the surface-hardened layer can be significantly reduced. You can

Further, in the invention of claim 6, all the surfaces of the outer and inner bushes can be easily formed as a surface-hardened layer by nitriding treatment, which also significantly increases the manufacturing cost of the surface-hardened layer. It can be reduced.

Further, in the invention of claim 7, dust can be reliably prevented from entering from the outside between the pin insertion hole of the inner bush and the connecting pin by another seal member, and the pin insertion hole of the pin insertion hole can be reliably prevented. It is possible to reliably prevent the inner peripheral surface and the outer peripheral surface of the connecting pin from being worn or damaged, and it is possible to reliably prevent rattling and the like between the inner bush and the connecting pin.

[Brief description of drawings]

FIG. 1 is an external view showing a working device of a hydraulic shovel to which a bearing device according to a first embodiment of the present invention is applied.

FIG. 2 is an enlarged vertical cross-sectional view of the bearing device as seen from the direction of arrows II-II in FIG.

FIG. 3 is an enlarged vertical sectional view showing an outer bush, an inner bush, a surface hardened layer and the like in FIG.

FIG. 4 is a longitudinal sectional view showing an inner bush in FIG. 3 in an enlarged manner.

FIG. 5 is a vertical sectional view similar to FIG. 2, showing a bearing device according to a second embodiment of the present invention.

FIG. 6 is an enlarged vertical sectional view showing an outer bush in FIG.

FIG. 7 is a vertical sectional view similar to FIG. 3, showing a bearing device according to a third embodiment of the present invention.

FIG. 8 is a view showing an outer bush, an inner bush, a surface hardened layer, a solid lubricant and the like according to a fourth embodiment of the present invention.
It is a principal part expanded sectional view similar to.

[Explanation of symbols]

11 Arm Boss (Boss Member) 13 Bush Fitting Hole 15 Bracket (Mating Member) 16, 31, 41 Outer Bush 16A, 16B, 31A, 31B, 41A, 41B Sliding Surface 17, 32, 43, 51 Inner Bush 18A, 33A , 44A, 52A pin insertion holes 18C, 19A, 33C, 34A, 44C, 45A, 5
2C, 53A Sliding surface 19, 34, 45, 53 Collar part 20, 35, 36, 46 Surface hardened layer 21 Connecting pin 22 Seal accommodation space 23 Seal member 42, 54 Solid lubricant 48 Other seal member G Grease (lubrication Agent)

Claims (7)

[Claims] 1. A bearing device comprising a boss member having a bush fitting hole formed in the axial direction and a connecting pin for rotatably connecting the boss member to a mating member. The bearing device is formed from a sintered oil-impregnated alloy into a tubular shape. An outer bush fitted in the bush fitting hole of the boss member, an outer circumference of which is slidably fitted in the outer bush, and an inner circumference of which is formed with a pin insertion hole for the connecting pin. A bush and a flange portion formed on the outer peripheral side of the inner bush so as to be in sliding contact with the end surface of the outer bush, and forming a seal receiving space between the bush and the boss member, and between the flange portion and the boss member. And a sealing member that seals between the outer bush and the inner bush, the surface hardening layer being formed on the inner bush at least on the sliding surface side of the outer bush. What you did A bearing device. 2. A bearing device comprising a boss member having a bush fitting hole formed in the axial direction and a connecting pin for rotatably connecting the boss member to a mating member, the fitting device being fitted in the bush fitting hole of the boss member. The outer bush attached to the outer bush is slidably fitted in the outer bush, and the inner bush is formed with a pin insertion hole for the connecting pin on the inner circumference and slidably contacts the end surface of the outer bush. As described above, the collar portion is formed on the outer peripheral side of the inner bush and forms a seal accommodating space with the boss member, and is disposed in the seal accommodating space between the collar portion and the boss member, A seal member for sealing between the outer bush and the inner bush is provided, and a surface hardened layer is formed on at least the sliding surface side of the outer bush and the inner bush among the surface of the inner bush and the surface of the outer bush. A bearing device is characterized in that a lubricant is supplied to the sliding surface. 3. A bearing device comprising a boss member having a bush fitting hole formed in the axial direction and a connecting pin for rotatably connecting the boss member to a mating member, the bearing device being formed of a copper alloy into a tubular shape, An outer bush fitted in a bush fitting hole of the boss member, and an inner bush having an outer peripheral side slidably fitted in the outer bush and a pin insertion hole for the connecting pin formed on the inner peripheral side. A flange portion formed on the outer peripheral side of the inner bush so as to be in sliding contact with the end surface of the outer bush, and forming a seal accommodating space between the outer bush and the boss member; and between the flange portion and the boss member. A seal member disposed in the seal accommodating space is provided, which seals between the outer bush and the inner bush, and the inner bush has a surface-hardened layer formed on at least the sliding surface side of the outer bush, And before A bearing device characterized in that the outer bush is provided with a solid lubricant on the sliding surface side with the inner bush. 4. A bearing device comprising a boss member having a bush fitting hole formed in the axial direction and a connecting pin for rotatably connecting the boss member to a mating member, wherein a surface hardening layer is provided at least on the inner peripheral surface side. An outer bush formed and fitted in a bush fitting hole of the boss member is slidably fitted in the outer bush on the outer peripheral side, and a pin insertion hole for the connecting pin is formed on the inner peripheral side. An inner bush, a flange portion formed on the outer peripheral side of the inner bush so as to be in sliding contact with the end surface of the outer bush, and forming a seal accommodating space between the inner bush and the boss member; and the flange portion and the boss member. And a seal member for sealing between the outer bush and the inner bush, the inner bush being formed of a copper alloy into a tubular shape, and the inner bush being Outside A bearing device characterized in that a solid lubricant is provided on a sliding surface side with respect to a bush. 5. The bearing device according to claim 1, wherein the surface hardened layer is formed by carburizing. 6. The bearing device according to claim 1, wherein the surface hardened layer is formed by a nitriding treatment. 7. The bearing according to claim 1, 2, 3, 4, 5 or 6, wherein another seal member is provided on the inner peripheral side of the inner bush between the inner bush and the outer peripheral surface of the connecting pin. apparatus.