JPH09273539A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of abrasion and damage between connection pins and brackets and compensate smooth relative rotation between boss members and the brackets. SOLUTION: Boss-side bushs are press-fitted to an inner peripheral side of an arm boss 18, while a pair of brackets 11 are arranged so as to sandwich the arm boss 18 from both sides in an axial direction. A self-lubricant bracket side bush 21 is press-fitted into each bracket 11. Connection pins 22 are inserted into pin through holes 19A, 21B of the bushes 19 and 21 for boss side and bracket side, for rotatably connecting the arm boss 18 to the brackets 11.

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 Generally, in construction machines such as hydraulic excavators, for example, a boom, an arm, and a bucket of a working device are rotatably connected to each other by a bearing device serving as a pin connecting device, and excavation work such as earth and sand is performed. At times, the boom, the arm, and the bucket are extended and retracted so that the boom, the arm, and the bucket are respectively raised and lowered (rotated).

Here, as the bearing device (pin coupling device), for example, as described in Japanese Utility Model Laid-Open No. 2-112743 or Japanese Utility Model Laid-Open No. 3-48118, the inner peripheral side is provided on the tip side of the arm. A cylindrical boss member having a bush fitting hole formed therein, a boss-side bush that is press-fitted into the bush fitting hole of the boss member, and has a pin insertion hole formed on the inner peripheral side, and the bush. And a connecting pin slidably fitted in the pin insertion hole and rotatably connecting the boss member between brackets of a bucket as a counterpart member.

In this type of conventional bearing device, the axial end of the connecting pin is fixed to each bracket provided on the bucket in a detent state by a retaining means, and a boss member of the arm is provided. The boss member is rotated around the connection pin with respect to each bracket by slidably inserting an intermediate portion in the axial direction of the connection pin through a bush on the boss side. .

Further, a grease injection path or the like extending from one end side toward the sliding surface between the connecting pin and the bush on the boss side is formed in the inside of the connecting pin, and grease or the like is formed on the sliding surface. By periodically filling the paste-like lubricating oil, the connecting pin can be smoothly rotated with respect to the boss member.

[0006]

By the way, in the above-mentioned bearing device according to the prior art, the retaining means for fixing the connecting pin and each bracket is formed with a play of an allowable dimension in consideration of ease of assembly and the like. There is. Also, for the same reason, the diameter of the pin insertion hole formed in each bracket is larger than the outer diameter of the connecting pin,
A relatively large gap is formed between the connecting pin and each bracket. For this reason, the connecting pin and each bracket are not completely fixed, and during excavation work with a bucket, a slight movement (displacement) between them occurs corresponding to the allowable dimension of the retaining means.

As a result, when the bucket is rotated relative to the arm during excavation of earth and sand, seizure, galling or uneven wear may occur between the connecting pin and each bracket, and the bucket may rotate. Sometimes such wear,
There is a problem in that abnormal noise or the like caused by the damage is generated.

The present invention has been made in view of the above-mentioned problems of the prior art, and wears between the connecting pin and each bracket,
An object of the present invention is to provide a bearing device capable of effectively preventing damage and the like and compensating for smooth relative rotation between the boss member and each bracket for a long period of time.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 employs a bearing device having a boss member having a bush fitting hole formed in an axial direction,
A cylindrical boss side bush that is press-fitted into the bush fitting hole of the boss member and has a pin insertion hole formed on the inner peripheral side, and the boss member is disposed so as to sandwich the boss member from both axial ends, A pair of brackets having bush fitting holes formed in the same direction, and a bracket bush having self-lubricating properties that is press-fitted into the bush fitting holes of each bracket and has pin insertion holes formed on the inner peripheral side, The bracket side bush and the boss side bush are respectively inserted into the pin insertion holes,
A connecting pin that rotatably connects the boss member to each bracket.

With this structure, even if the connecting pin is slightly rotated in each bracket, it is possible to prevent the bracket and the connecting pin from directly sliding, and the bracket side bush having self-lubricating property is provided. On the other hand, it is possible to prevent the sliding and displacement of the connecting pin from causing wear and damage between each bracket and the connecting pin.

In this case, according to the second aspect of the present invention, the bracket side bush is formed as a cylindrical body from any one of the engineering plastic materials made of polyimide, polytetrafluoroethylene or polyetheretherketone. ing.

As a result, the bracket side bush can be easily formed, the bracket and the connecting pin can be prevented from directly sliding, and the connecting pin is slidably displaced with respect to the bracket side bush made of an engineering plastic material. As a result, it is possible to suppress the occurrence of wear and damage between each bracket and the connecting pin.

Further, in the invention according to claim 3, in the bush fitting hole of the boss member, the lubricating oil lubricated between the boss member and the connecting pin is prevented from leaking to the bracket side. An oil seal is provided, and a thrust plate made of a self-lubricating material is provided between the boss member and each bracket and is located on the outer peripheral side of the connecting pin.

With this structure, it is possible to prevent the boss member and each bracket from directly sliding, and it is possible to suppress the abrasion between the boss member and each bracket. Further, the oil seal provided in the bush fitting hole of the boss member can seal between the boss member and the connecting pin, and the lubricating oil lubricated between the boss member and the connecting pin can be prevented from leaking to the bracket side. At the same time, it is possible to prevent dust from entering the sliding surface between the boss side bush and the connecting pin from the outside.

Further, in the invention according to claim 4, an annular collar portion is formed on the outer peripheral side of the boss side bush so as to be in sliding contact with the end surface of each bracket, and between the boss side bush and the connecting pin. In this configuration, an oil seal is provided on the inner peripheral side of the collar portion.

With this configuration, when the boss member and each bracket are relatively displaced (rotated), the collar portion of the boss side bush can be slidably contacted with the end surface of each bracket. For example, each bracket The thrust direction (axial direction) load from can be received by the collar portion. In addition, an oil seal provided between the boss side bush and the connecting pin can seal between the boss side bush and the connecting pin, preventing the lubricating oil injected between the two from leaking to the bracket side, and It is possible to prevent dust and the like from entering the sliding surface between the side bush and the connecting pin from the outside.

Furthermore, in the invention described in claim 5,
A ring-shaped seal member is mounted between the boss member and each bracket so as to close the gap between them from the outer peripheral side.

As a result, it is possible to prevent dust or the like from entering from the outside between the relative rotating boss member and each bracket.

[0019]

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

1 to 3 show the first embodiment of the present invention.

In the drawing, 1 is a lower traveling body of a hydraulic excavator, 2 is an upper revolving body which is a work machine body mounted on the lower traveling body 1 so as to be rotatable, and the upper revolving body 2 is a revolving frame 3 And a cab 4, on the revolving frame 3,
A machine room 5, a counterweight 6 and the like are provided.

Reference numeral 7 denotes a working device provided on the front part of the upper revolving structure 2 so as to be able to move up and down. The working device 7 is a boom 8 pin-connected to the revolving frame 3 of the upper revolving structure 2 and the boom. 8 is composed of an arm 9 pin-coupled to the tip side and a bucket 10 and the like pin-coupled to the tip side of the arm 9. The bucket 10 includes a pair of left and right brackets 11 and 11 (see FIG. 2). (See) is integrally provided by means such as welding. Then, the boom 8 of the work device 7 is lifted up and down by the boom cylinder 12, and the arm 9 is lifted.
Is raised and lowered with respect to the boom 8 by the arm cylinder 13.

Further, the bucket cylinder 14 has its rod tip side pin-coupled to the pair of links 15 and 16, and one of the links 15 and 16 is pin-coupled to the tip side of the arm 9 and the other one. Link 16 is bucket 1
It is pin-connected to each bracket 11 of 0. And
By extending and contracting the bucket cylinder 14, the bucket 10 is rotated via the links 15 and 16 on the tip side of the arm 9.

Reference numeral 17 denotes a bearing device forming a pin coupling portion between the tip end side of the arm 9 and each bracket 11 of the bucket 10. The bearing device 17 is provided at the tip end side of the arm 9 as shown in FIG. The arm boss 18 is provided, which will be described later, each bracket 11 of the bucket 10, and a connecting pin 22, which will be described later, that rotatably connects the arm boss 18 between the brackets 11.

Reference numeral 18 denotes an arm boss as a boss member integrally provided on the tip side of the arm 9 by means such as welding, and the arm boss 18 is formed of a metal material such as cast iron into a substantially cylindrical shape. Bush fitting hole 18 on the inner peripheral side
A is provided.

Further, annular taper portions 18 are provided on the outer peripheral side of the end surfaces 18B located on both axial ends of the arm boss 18, respectively.
C is formed, and the tapered portions 18C and the tapered portions 11C of the brackets 11 form a V-shaped groove on the facing surface of the arm boss 18 and the bracket 11, as shown in FIG.

On the other hand, each bracket 11 has an arm boss 18
Each end surface 18B and each end surface 11B are arranged to face each other, a bush fitting hole 11A is formed in each bracket 11, and one bracket 11 of the pair of brackets 11, 11 will be described later. A bolt insertion hole 11D for inserting the fixing bolt 23 is formed. Here, the hole diameter of the bolt insertion hole 11D is formed larger than the outer diameter of the fixing bolt 23 in order to facilitate the assembling work.

Reference numerals 19 and 19 denote boss-side bushes respectively press-fitted and fitted into the bush-fitting holes 18A of the arm boss 18, and each boss-side bush 19 is formed of a sintered oil-impregnated iron-copper alloy into a cylindrical shape. Then, the arm boss 18 is fitted into the bush fitting hole 18A with a certain tightening margin.
A pin insertion hole 19A into which a connection pin 22 described later is slidably inserted is formed on the inner peripheral side of each boss side bush 19, and the peripheral surface of the pin insertion hole 19A slides on the connection pin 22. It is the moving surface 19B. Further, the hole diameter of the pin insertion hole 19A is formed to be larger than the outer diameter of the connecting pin 22 so that the connecting pin 22 can be easily inserted into the pin insertion hole 19A.

Reference numeral 20 denotes a bush fitting hole 1 of the arm boss 18.
8A axially middle part is press-fitted to each boss side bush 1
9 shows a cylindrical body that is arranged so as to be sandwiched between 9, and the outer diameter of the cylindrical body 20 is approximately equal to the hole diameter of the bush fitting hole 18A, and each boss-side bush 19 is located on the intermediate side in the axial direction. At the inner peripheral side of the cylindrical body 20, a lubricant oil G that is compatible with the oil liquid impregnated in each boss-side bush 19
Is filled.

Reference numerals 21 and 21 denote bracket side bushes provided in the bush fitting holes 11A of the brackets 11. The bracket side bushes 21 are made of, for example, polyimide, polytetrafluoroethylene (PTFE) or polyether ether ketone (PEEK). ) And the like are formed into a cylindrical shape by a self-lubricating material made of engineering plastic. Then, each bracket side bush 21
Is formed so that its axial dimension is slightly shorter than the axial dimension of each bracket 11, and the end surface 21 of each bracket-side bush 21 is smaller than the end surface 11B of each bracket 11.
They are press-fitted so that A is located in the bush fitting hole 11A.

Further, a pin insertion hole 21B having a hole diameter substantially equal to the hole diameter of the pin insertion hole 19A of the boss side bush 19 is formed on the inner peripheral side of each bracket side bush 21, and the pin insertion hole 21B is formed. The peripheral surface of 21A is a connecting pin 22 described later.
And a sliding surface 21C. Further, one of the pair of bracket side bushes 21, 21 has a bolt insertion hole having a hole diameter substantially equal to the hole diameter of the bolt insertion hole 11D at a position corresponding to the bolt insertion hole 11D of the bracket 11. 21D is drilled.

Reference numeral 22 denotes an arm boss 1 between each bracket 11.
8 is a rotatable connecting pin.
2 is formed in a columnar shape, for example, of carbon steel S45C and heat-treated steel obtained by surface-modifying the carbon steel S45C.
9 and each pin insertion hole 1 of each bracket side bush 21
The arm boss 18 is rotatably connected between the brackets 11 by being fitted into the brackets 9A and 21B. Here, the outer diameter of the connecting pin 22 is smaller than the hole diameters of the respective pin insertion holes 19A and 21B so that the connecting pin 22 can be easily inserted into the respective pin insertion holes 19A and 21B during the assembling work. The connecting pin 22 and each pin insertion hole 19A, 2
There is a clearance with 1B.

Further, on one end side of the connecting pin 22 in the axial direction, holes having substantially the same diameters as the bolt insertion holes 11D, 21D are provided at positions corresponding to the bolt insertion holes 11D, 21D of the bracket 11 and the bracket side bush 21. A bolt insertion hole 22A having a diameter is formed.

A concave portion 22B is formed on the other end side end surface of the connecting pin 22 on the center side thereof, and the base end side of the lubricating oil injection passage 22C is open on the bottom side of the concave portion 22B. On the other hand, the front end side of the lubricating oil injection passage 22C is an axially intermediate portion L
It is bent in a letter shape and opens to the inner peripheral side of the tubular body 20 fitted in the bush fitting hole 18A of the arm boss 18. When the lubricating oil G is filled in the arm boss 18,
Lubricating oil G is injected into the arm boss 18 from the nipple portion 27 side described later through the lubricating oil injection passage 20C.

Reference numeral 23 denotes each of the bolt insertion holes 11D of the bracket 11, the bracket side bush 21 and the connecting pin 22.
The fixing bolts 21D and 22A are inserted into the fixing bolts 24, and the fixing bolts 23 are fixed bolts 23 into the bolt insertion holes 11D, 21D and 22A.
A fixed nut screwed to the tip side of the fixed nut in a state of being inserted therein is shown, and the fixed nut 24 holds the fixing bolt 23 in a loosened state. The fixing bolt 23 and the fixing nut 24 together with the connecting pin 2 are attached to the bracket 11.
The retaining means is configured to hold 2 in a rotation-preventing and retaining state. Further, the hole diameters of the bolt insertion holes 11D, 21D, 22A are formed to be larger than the outer diameter of the fixing bolt 23, and the fixing bolt 23 and the bolt insertion holes 11D,
There is a gap between 21D and 22A.

Reference numerals 25 and 25 denote end faces 18 of the arm boss 18.
A ring-shaped dust seal mounted in the bush fitting hole 18A from the B side.
The two boss-side bushes 19 are in contact with the axially outer end surfaces of the respective boss-side bushes 19, and their lip portions 25A are in sliding contact with the outer peripheral side of the connecting pin 22. The dust seals 25 are provided on the boss side bushes 19 in the arm boss 18.
It prevents dust and the like from entering from the outside between the sliding surface 19B and the outer peripheral surface of the connecting pin 22.

Reference numerals 26 and 26 denote O-rings as seal members, and each O-ring 26 is, as shown in FIG. 3, each bracket 11 and each tapered portion 11C of the arm boss 18.
It is mounted in a state of elastically contacting 18C to prevent dust and the like from entering between the end faces 11B and 18B of each bracket 11 and arm boss 18.

27 is a lubricating oil injection passage 22C for the connecting pin 22.
The nipple portion is screwed to the base end side, and the nipple portion 27 is fitted with an injection gun (not shown) for the lubricating oil G to inject the lubricating oil G from the outside into the lubricating oil injecting passage 22C. It is what makes me.

Bearing device 1 for hydraulic excavator according to the present embodiment
Reference numeral 7 denotes a bearing device having the above-described configuration.
The bucket 10 pin-joined to the tip side of the arm 9 via 7 rotates the connecting pin 22 fixed to the bracket 11 relative to each boss side bush 19 mounted in the arm boss 18 of the arm 9. Thus, the bucket 10 is allowed to rotate up and down on the tip side of the arm 9.

Here, when each bracket 11 is rotated relative to the arm boss 18 in the excavation work of, for example, earth and sand, the outer peripheral surface of the connecting pin 22 and the sliding surface 19B in the boss side bush 19 are brought into contact with each other. When sliding resistance occurs, the connecting pin 22 is fixed to the bracket side bush 21 in each bracket 11 with the fixing bolt 23 and each bolt insertion hole 11
It will be slightly slid (rotated) displaced within the range of the clearance dimension generated between D, 21D and 22A.

However, at this time, since the connecting pin 22 is slightly slid and displaced with respect to the sliding surface 21C of each bracket side bush 21 made of a self-lubricating material, these sliding surfaces 21C and the like are lubricated. Can be kept and connecting pin 22
Outer peripheral surface and bush fitting hole 11 of each bracket 11
It is possible to effectively prevent the A from being worn or damaged at an early stage or causing looseness.

Further, the lubricating oil G filled in the inner peripheral side of the tubular body 20 is moved to the bracket 11 side through the clearance generated between the sliding surface 19B of the boss side bush 19 and the outer peripheral surface of the connecting pin 22. And the end surface 11 of each bracket 11
It is also supplied between B and each end surface 18B of the arm boss 18 which faces. Therefore, even if each bracket 11 and each end surface 11B, 18B of the arm boss 18 are in sliding contact with each other, each end surface 11B, 18B is not worn.

On the other hand, the connecting pin 22 and each boss side bush 1
Lubricating oil G that is periodically injected into the gap between 9 may leak to the outside through this gap and may be partially supplied between the connecting pin 22 and each bracket 11. It is also possible to keep the space between the connecting pin 22 and each bracket 11 in a lubricated state by G. However, when the lubrication interval of the lubricating oil G is greatly extended or when each boss side bush 19 is a non-greasing bearing, the connecting pin 22
Lubricating oil G or the like is not supplied between the brackets 11 and 11, which may cause a poor lubrication state, and slight sliding between the two may easily cause wear or the like at an early stage.

Therefore, in the bearing device 17 according to the present embodiment, when the bracket-side bushes 21 made of a self-lubricating material are provided in the bush fitting holes 11A of the brackets 11, the greasing interval is significantly extended. Even when using a non-greasy bearing, the connecting pin 22 is attached to each bracket 11
On the other hand, the bracket-side bushes 21 can be smoothly slid on each other, and wear and damage between the two can be reliably prevented.

Thus, in this embodiment, the arm bosses 18 in which the respective boss-side bushes 19 are press-fitted on the inner peripheral side and the arm bosses 18 are arranged so as to sandwich the arm bosses 18 from both axial ends.
Each bracket side bush 2 with self-lubrication on the inner circumference side
1 is press-fitted into the pair of brackets 11, and the boss-side bushes 19 and the bracket-side bushes 21 are respectively inserted into the pin insertion holes 19A and 21B, so that the arm bosses 18 can be pivoted to the brackets 11. Since the bearing device is composed of the connecting pin 22 to be connected, each bracket 1
Even when the connecting pin 22 slightly rotates (slides) in the inside 1, it is possible to prevent each bracket 11 and the connecting pin 22 from directly sliding, and to prevent wear and abrasion between each bracket 11 and the connecting pin 22. It can prevent damage.

Since the bracket side bush 21 is made of an engineering plastic material, the bracket side bush 21 can be easily machined and formed, and each bracket side bush 2 having self-lubricating property.
By smoothly sliding and displacing 1 with respect to the connecting pin 22, it is possible to prevent the bush fitting hole 18A peripheral surface of each bracket 11 and the outer peripheral surface of the connecting pin 22 from being worn or damaged.

Further, each bracket 11 and the connecting pin 22
It is possible to prevent seizure, galling, or uneven wear that occurs between and, so that it is possible to reliably prevent generation of abnormal noise due to such wear and damage during rotation of the bucket 10, for a long period of time. It is possible to compensate for smooth rotation of each bracket 11 with respect to the arm boss 18 over the entire length.

Next, FIGS. 4 and 5 show a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. To do. However, the feature of this embodiment is that the bearing device 31 is attached to the arm boss 18.
The ring-shaped oil seals 32, 32 are mounted in the bush fitting holes 18A from the respective end surfaces 18B of the respective end surfaces 18B of the arm bosses 18 and the end surfaces 11 of the brackets 11.
Thrust plate 3 formed as an annular thin plate between B and
The third and third elements are arranged to be rotatable.

Here, each oil seal 32 is a ring portion 32 in which a cored bar is embedded and which has an elastic body and has a substantially L-shaped cross section.
A and two lip portions 32B and 32C located on the inner peripheral side of the ring portion 32A and made of an elastic body. The oil seals 32 are attached to the arm bosses 18
Is disposed in each bush fitting hole 18A on the side of each end surface 18B and is slightly separated from the axially outer end surface of each boss side bush 19.

Further, the lip portion 32 of each oil seal 32
One lip portion 32B of B and 32C extends outward in the axial direction and is in sliding contact with the outer peripheral side of the connecting pin 22, and a sliding surface between each boss side bush 19 in the arm boss 18 and the connecting pin 22. It prevents dust and the like from entering the outside. On the other hand, the other lip portion 32C extends toward the intermediate portion side in the axial direction by a thick elastic body and slidably contacts the outer peripheral surface of the connecting pin 22, and a metal ring 32D is provided on the inner peripheral side thereof. The lip portion 32C is strongly urged toward the outer peripheral side of the connecting pin 22 to prevent the lubricating oil G from leaking to the outside.

Further, each thrust plate 33 is formed of engineering plastic or the like having the same self-lubricating property as that of the bracket side bush 21.
A connecting pin 22 is inserted into the inner peripheral side of 3 through a predetermined gap. Both side surfaces of each thrust plate 33 are respectively attached to each end surface 1 of each bracket 11 and arm boss 18.
It is a sliding surface for 1B and 18B.

Thus, in this embodiment having the above-mentioned structure, it is possible to obtain substantially the same operational effects as those of the first embodiment. However, particularly in this embodiment, each oil seal 32 is provided.
Is provided on the axially outer side of the boss-side bush 19, it is possible to effectively prevent the lubricating oil G from leaking from the inside of the arm boss 18 to the side of each bracket 11, and the sliding surface 19B of each boss-side bush 19 and the connecting pin. It is possible to maintain a lubricated state between the outer peripheral surface of 22 and the outer peripheral surface for a long period of time, and to significantly extend the greasing interval.

Further, each bracket 11 and arm boss 18
Since the thrust plates 33 made of a self-lubricating material are disposed between the end faces 11B, 18B of
18B slides smoothly on both side surfaces of each thrust plate 33, and it is possible to prevent wear and damage between the end surfaces 11B and 18B.

Furthermore, even when a shock or the like acts on the bearing device 31 via the bucket 10 during excavation work,
When each thrust plate 33 receives the thrust load from the end surface 11B of each bracket 11 or the end surface 18B of the arm boss 18, each bracket 11 and arm boss 1
8 can be prevented from directly colliding with each other, and the bracket 11 and the end surfaces 11B and 18B of the arm boss 18 can be reliably prevented from being worn or damaged.

Next, FIGS. 6 and 7 show a third 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 is omitted. To do. However, the feature of this embodiment is that the arm boss 42 of the bearing device 41 is
A stepped tubular boss side bush 43 is provided inside, and an oil seal 44 is provided between the boss side bush 43 and the connecting pin 22.

Here, the arm boss 42 is formed in a substantially cylindrical shape from a metal material such as cast iron, and is integrally fixed to the tip end side of the arm 9 by means such as welding. A bush fitting hole 42A having a hole diameter substantially equal to the outer diameter of the cylindrical portion 43A of the boss side bush 43 is provided on the inner peripheral side of the arm boss 42.

Also, annular taper portions 42 are provided on the outer peripheral side of the end faces 42B located on both axial ends of the arm boss 42.
C is formed, and the tapered portions 42C and the tapered portions 11C of the brackets 11 form V-shaped grooves on the facing surfaces of the arm boss 42 and the bracket 11 as shown in FIG. And each taper part 11C, 42C
The O-ring 26 is elastically attached to the
Each end face 11 of each bracket 11 and arm boss 42
It prevents dust and the like from entering between B and 42B.

Further, the collar portion 43 of each boss side bush 43 is provided on the inner peripheral side of the arm boss 42 located on the side of each end surface 42B.
A fitting recess 42D having an inner diameter substantially equal to the outer diameter of B is formed in an annular shape, and each fitting recess 42D is formed in the bush fitting hole 4
It forms a stepped hole with 2A.

On the other hand, each boss side bush 43 is formed in a stepped cylindrical shape from, for example, an iron-copper-based sintered oil-impregnated alloy, and has a cylindrical portion 43A and a diameter from the outer peripheral side on the axially outer side of the cylindrical portion 43A. And a thick flange portion 43B protruding outward in the direction. A pin insertion hole 43C is bored in the axial direction on the inner peripheral side of the cylindrical portion 43A, and the inner peripheral surface of the pin insertion hole 43C has a connecting pin 22. Is a sliding surface 43D. Also, the collar part 4
An annular recess 43E is provided axially outside the pin insertion hole 43C located on the inner peripheral side of 3B, and an oil seal 44 is disposed in the recess 43E.

Then, in each boss side bush 43, each cylindrical portion 43A is fitted in the bush fitting hole 42A, and each collar portion 4A.
3B is provided in the arm boss 42 while being fitted in the fitting recesses 42D. Here, the axial dimension of the collar portion 43B is set to be slightly larger than the axial dimension of the fitting recess 42D of the arm boss 42, and the axially outer end surface of each collar portion 43B contacts the end surface 11B of each bracket 11. It is accessible.

Further, each oil seal 44 has a ring portion 44A having a substantially L-shaped cross section formed by an elastic body in which a core metal is embedded, as in the oil seal 32 of the second embodiment, and the inside of the ring portion 44A. It is composed of two lip portions 44B, 44C located on the circumferential side and made of an elastic body. Each oil seal 44 is disposed in the recess 43E of each boss side bush 43, and one lip portion 44B is connected. The sliding contact with the outer peripheral surface of the pin 22 prevents dust and the like from entering the sliding surface between each boss side bush 43 and the connecting pin 22 from the outside, and the other lip portion 44C is made of metal. The ring 44D strongly urges the outer peripheral surface of the connecting pin 22 to prevent the lubricating oil G from leaking to the outside.

Thus, in this embodiment having the above-described structure, it is possible to obtain substantially the same effects as the first embodiment. However, in this embodiment, in particular, a stepped cylindrical shape is provided inside the arm boss 42. Since the boss side bush 43 is provided and the oil seal 44 is arranged between the boss side bush 43 and the connecting pin 22, the lubricating oil G is prevented from leaking from the inside of the arm boss 42 to each bracket 11 side. It can be effectively prevented and the sliding surface 43D of each boss side bush 43 and the connecting pin 2
It is possible to maintain a lubricated state between the second outer peripheral surface and the outer peripheral surface for a long period of time and to significantly extend the greasing interval.

Further, during the excavation work or the like, a twisting force or the like acts between the arm 9 and the bucket 10, so that each bracket 11
On the other hand, even when the arm boss 42 is relatively displaced in the axial direction, the collar portion 4 formed integrally with each boss side bush 43 is formed.
By contacting the end surface of 3B with the end surface 11B of the bracket 11, the axial load at this time can be reliably received,
It is possible to effectively prevent the end surface 42B of the arm boss 42 from colliding with (abutting against) each bracket 11 and causing the end surfaces 42B and 11B of the both to wear at an early stage or to cause rattling.

In the third embodiment, the collar portion 43B is used.
However, the present invention is not limited to this, and for example, an annular collar member and a cylindrical bush are formed separately, and the outer peripheral side of the bush is formed. The flange member may be press-fitted to be integrated with the flange member, and the flange member and the bush, which are separately formed, may be integrally fixed to each other via bolts or pins. Good.

Further, in each of the above-described embodiments, the case where the bearing device is applied to the pin connecting portion between the arm 9 and the bucket 10 of the hydraulic excavator has been described as an example, but the present invention is not limited to this and, for example, The present invention can be widely applied to other pin coupling parts such as a pin coupling part between the link 16 and the bucket 10 and a pin coupling part between the arm 9 and the arm cylinder 13.

[0066]

As described above in detail, according to the invention of claim 1, the cylindrical boss side bush is press-fitted into the bush fitting hole of the boss member, and the bush fitting hole of each bracket is provided. By press-fitting bracket-side bushes having self-lubricating properties and inserting the connecting pins into the pin insertion holes of the bracket-side bushes and the boss-side bushes,
Since the boss member is rotatably connected to each bracket, even if the connecting pin slightly rotates in each bracket, it is possible to prevent each bracket and the connecting pin from directly sliding, and self-lubricating. By slidingly displacing the connecting pin with respect to each of the bracket-side bushes, it is possible to prevent wear and damage between the bracket and the connecting pin.

Further, since seizure, galling or uneven wear which occur between each bracket and the connecting pin can be prevented, abnormal noise or the like due to such wear or damage is generated when the bucket or the like is rotated. Can be reliably prevented, and it is possible to compensate for smooth rotation of each bracket with respect to the boss member for a long period of time.

In this case, according to the second aspect of the present invention, the bracket side bush is formed into a cylindrical body by using one of the engineering plastic materials made of polyimide, polytetrafluoroethylene or polyetheretherketone. Since it is formed, the bracket side bush can be easily formed, direct contact between each bracket and the connecting pin can be prevented, and the connecting pin is slidably displaced with respect to each bracket side bush made of an engineering plastic material. By
It is possible to suppress the occurrence of wear and damage between each bracket and the connecting pin.

According to the third aspect of the invention, the lubricating oil supplied between the boss member and the connecting pin is prevented from leaking to the bracket side in the bush fitting hole of the boss member. Since an oil seal is provided and a thrust plate made of a self-lubricating material is provided on the outer peripheral side of the connecting pin between the boss member and each bracket, the boss member and each bracket are It is possible to prevent direct sliding on the end face side in the axial direction, and to prevent the boss member and each bracket from being worn between the end faces of both.
Further, the oil seal provided in the bush fitting hole of the boss member can seal between the boss member and the connecting pin, and the lubricating oil lubricated between the boss member and the connecting pin can be prevented from leaking to the bracket side. At the same time, dust from the outside can be prevented from entering the sliding surface between the boss side bush and the connecting pin.

On the other hand, each thrust plate receives the axial load from the end surface of each bracket or the end surface of the boss member even when an axial shock load is applied to the bearing device during excavation work. As a result, it is possible to prevent the brackets from directly colliding with the boss member, and it is possible to reliably prevent the brackets, the boss member, and the like from being worn or damaged.

Further, according to the fourth aspect of the present invention,
An annular collar portion is formed on the outer peripheral side of the boss side bush so as to be in sliding contact with the end surface of each bracket, and is located on the inner peripheral side of the collar portion between the boss side bush and the connecting pin. Since the oil seal is provided, when the boss member and each bracket are relatively displaced (rotated), the collar portion of the boss side bush can be slidably contacted with the end surface of each bracket. Axial load can be received by the collar. Also, an oil seal provided between the boss side bush and the connecting pin can seal between the boss side bush and the connecting pin, preventing the lubricating oil supplied between them from leaking to the bracket side. It is possible to prevent dust and the like from entering the sliding surface between the side bush and the connecting pin from the outside.

When the boss member is displaced relative to each bracket in the axial direction during excavation work or the like, the axial load at this time is reliably received by the flange portion formed on each boss side bush. Therefore, it is possible to effectively prevent the boss member from colliding with (abutting against) each bracket and prematurely wearing each end face of both.

Further, according to the invention of claim 5, a ring-shaped seal member is mounted between the boss member and each bracket so as to close the gap between them from the outer peripheral side. Therefore, it is possible to prevent dust and the like from entering from the outside between the boss member that relatively rotates and each bracket member.

[Brief description of drawings]

FIG. 1 is an overall view showing 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 cross-sectional view of a main part showing an arm boss, a bracket and the like in FIG.

FIG. 4 is a vertical sectional view showing a bearing device according to a second embodiment of the present invention.

5 is an enlarged cross-sectional view of an essential part of an arm boss, a bracket and the like in FIG.

FIG. 6 is a vertical sectional view showing a bearing device according to a third embodiment of the present invention.

7 is an enlarged cross-sectional view of a main part of an arm boss, a bracket and the like in FIG.

[Explanation of symbols]

 11 bracket 11A bush fitting hole 17,31,41 bearing device 18,42 arm boss (arm boss) 18A, 42A bush fitting hole 19,43 boss side bush 19A, 43C pin insertion hole 21 bracket side bush 21B pin insertion hole 22 connection Pin 23 Fixing bolt (prevention means) 24 Fixing nut (prevention means) 26 O-ring (seal member) 32,44 Oil seal 32B, 32C, 44B, 44C Lip part 33 Thrust plate 43B Collar part G Lubricating oil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Tobita No. 650 Jinrachicho, Tsuchiura City, Ibaraki Prefecture Hitachi Construction Machinery Co., Ltd. Tsuchiura Factory

Claims (5)

[Claims] 1. A boss member having a bush fitting hole formed in the axial direction, and a cylindrical boss side press-fitted into the bush fitting hole of the boss member and having a pin insertion hole formed on the inner peripheral side. A bush, a pair of brackets that are arranged so as to sandwich the boss member from both axial ends, and have a bush fitting hole formed in the axial direction, and are press-fitted into the bush fitting holes of the respective brackets. Self-lubricating bracket side bushes with pin insertion holes formed on the peripheral side and pin insertion holes of the bracket side bushes and the boss side bushes, respectively, and the boss member can be rotated to each bracket. A bearing device comprising a connecting pin connected to the. 2. The bearing device according to claim 1, wherein the bracket-side bush is formed as a tubular body from any one of engineering plastic materials made of polyimide, polytetrafluoroethylene, or polyether ether ketone. 3. In the bush fitting hole of the boss member,
An oil seal is provided between the boss member and the connecting pin to prevent the lubricating oil that has been lubricated from leaking to the bracket side, and is located on the outer peripheral side of the connecting pin between the boss member and each bracket. The bearing device according to claim 1 or 2, wherein a thrust plate made of a self-lubricating material is provided. 4. An annular collar portion is formed on the outer peripheral side of the boss side bush so as to be in sliding contact with the end surface of each bracket, and an inner periphery of the collar portion is formed between the boss side bush and the connecting pin. The bearing device according to claim 1 or 2, wherein an oil seal is provided on the side. 5. The bearing according to claim 1, 2, 3 or 4, wherein a ring-shaped seal member is mounted between the boss member and each bracket so as to close a gap between the boss member and the bracket from the outer peripheral side. apparatus.