JPH09242109A - Arm structure for excavating work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain respective structures of an arm for excavating works, especially the boom in the arm, which is low in the cost and copes with the enlarging trend while securing the strength. SOLUTION: This boom 1 is constituted of a rear sheet plate 3, a front sheet plate 4, and right and left side plates 2, 2 divided into two front side plate 2a and the rear side plate 2b, which are welded together. Bulging parts 5a, 5b are provided at both rear and front sides in the arm bracket plate 5 of the front end to cover the welded parts 6a, 6b to the rear and front plates 3, 4 of a front end rib 6. The arm bracket plate 5 is not extended to the position where intermediate ribs 7 of the front end are arranged and cut off on the way. The clamp seat 11 for piping is superposed with the contact part of the side plate 2 in the rear plate 3 to provide a welded part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a boom among excavation work arms supported by a swing work vehicle or an excavation work vehicle.

[0002]

2. Description of the Related Art An excavation work vehicle or the like is provided with an excavation work arm including a boom, an arm, and a bucket. In the boom structure therein, first, an arm bracket plate for pivotally supporting the arm base end is arranged at the tips of the left and right side plates. At the tip of the boom, the rib connecting the two tips of the back plate and the abdominal plate (tip rib) and the middle rib of the boom tip arranged between the left and right side plates (rib in the tip) are It was arranged between the arm bracket plates. This is because stress is applied to the arm bracket plate from the pivotal support part at the base end of the arm, so it is attempted to reinforce it and both the tip rib and the middle rib are placed between the left and right arm bracket plates. It has been done. Known examples of this are as follows: Jikho Sho 63-19406, Jikkaihei 5-10.
There is 541. Further, the tip ribs are in a state where the welded portions to the back plate and the abdominal plate protrude from the back plate-side end and the abdominal plate-side end of the arm bracket plate.

Further, the boom is conventionally constructed by welding four plate members, one plate each of a back plate, an abdominal plate, and left and right side plates, as in the case of the actual open flat plate 3-2057.

[0004] Further, as in the case of Japanese Utility Model Laid-Open No. 2-109852, conventionally, a boom back plate is provided with a pipe clamp member for fixing a hydraulic hose to an arm cylinder or a bucket cylinder. It is welded to the plate and the end of the back plate.

Further, there is seen a structure in which the excavation work arm is provided with a pivot portion at each portion, and for example, a boss at the base end of the arm is pivotally supported by a pivot pin between the left and right bracket plates at the tip of the boom. In such a pivotal support structure using a pivotal pin, a turning force is applied to the pivotal pin by the bending and stretching motion of the excavation work arm. Therefore, the pivot pin requires a detent structure. Conventionally, of the left and right bracket plates, a washer fixed to one end of the pivot pin is screwed to one of the bracket plates, or a member for preventing rotation is provided.
Among them, as the former structure, those shown in FIGS. 18 to 20 which will be described later in detail are known. Among them, the one shown in FIG. 18 is a basic structure with one rotation stopping bolt. In FIGS. 19 and 20, two bolts are used, and in addition, a rotation preventing member is used. Japanese Patent Laid-Open No. 7-20
The structure disclosed in 8448 is similar to this. As the latter structure, as shown in FIGS.
A structure is known in which a plate member for preventing rotation is arranged close to a washer fixed to the pivot pin, and a retaining bolt (or split pin) is radially inserted into the other end of the pivot pin. Has become. Further, the pivotal support structure disclosed in Japanese Utility Model Laid-Open No. 7-35552 is a pivotal support structure of the bucket base end with respect to the arm tip, but here, the end portion side where the washer of the pivot support pin is not fixed is fixed with a bolt or the like. A non-rotating structure is disclosed.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an improvement of an arm of a revolving work vehicle or the like, and relates to an improvement of the strength of the arm, a welding position, and the like. Since the arm bracket plate at the tip of the boom is thick, it is desirable to make the front-rear length as short and short as possible for weighing. However, in the past, in order to secure the stress, it was considered necessary to secure the length up to the location of the rib in the tip disposed between both side plates of the boom. It was supposed to be.

Further, as the vehicle body becomes larger, the working arm also becomes larger accordingly, and in particular, the side plate of the boom has a complicated shape and requires the longest length as the size increases.
If the side plate is composed of one plate as described above, it is inconvenient to form a side plate that is longer than the component yield. On the contrary, even if all four plate materials including the back plate and the abdominal plate are divided into two and welded, the number of welded parts increases and the boom strength decreases.

Further, when the welding position of the pipe clamp member is as described above, when a twisting force is applied to the boom, there is a problem that stress is generated at a welded portion having poor strength.

In addition, in the pivotal support structure by the pivotal support pin provided in each part of the working arm, FIG.
8 As shown in the figure, to prevent rotation with a single anti-rotation bolt, the bolt cannot withstand the rotational force applied to the pivot pin when the work arm is bent and stretched, and the bolt is cut off and the pivot pin falls off. There is a risk. 19 and 20, and JP-A-7-208.
If other members or a plurality of bolts are used to prevent rotation, such as 448 and actual open flat 7-35552, the rotation prevention of the pivot pin can be strengthened, but the number of parts is large and the cost is increased. On the other hand, as shown in FIGS. 21 and 22, with the structure in which the side of the pivot pin on which the washer is fixed is prevented from rotating and the other end is prevented from coming off with a bolt or split pin, the bolt or split pin easily deforms. , If the work of attaching and detaching the pivot pin is repeated, there is concern about reuse.

[0010]

SUMMARY OF THE INVENTION The present invention has solved the above problems and has made it possible to reduce the weight and strength of the boom tip, to enable mass production in response to an increase in the size of the boom, and for pipes against the torsional stress applied to the boom. The following means are used to secure the strength of the clamp seat. First of all, at the tip of the boom of the excavation work vehicle, in the structure where the arm bracket plates are attached to the respective ends of the left and right side plates of the boom, the entire rib connecting the both ends of the back plate and the abdominal plate of the boom is attached to the arm. While covering with the bracket plate, the middle rib of the boom tip is disposed between the boom both side plates in the non-overlapping portion of the arm bracket plate.

Second, in the boom structure of the excavation work vehicle constructed by welding the back plate, the abdominal plate, and the left and right side plates, the back plate and the abdominal plate are one plate, and the left and right side plates are divided into two parts. And

Thirdly, in the structure in which the pipe clamp seat is welded to the back plate of the boom of the excavation work vehicle, the welded part of the pipe clamp seat is set to the contact part of the left and right side plates of the boom with the back plate. Polymerize.

Fourth, in a structure in which a boss provided on each part of the excavation work arm is pivotally supported by loosely fitting a pivot pin between the left and right bracket plates, a washer is fixed to one end of the pivot pin. One bracket bolt is screwed to one bracket plate, and a washer is fixed to the other end or a retaining ring is annularly attached to the other end to prevent the bracket plate from coming off.

[0014]

Embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a side view of a boom 1 according to the present invention, and FIG. 2 is a front side plate 2a of a basic constituent plate member of the boom 1.
A side view of the rear side plate 2b, the back plate 3 and the abdominal plate 4 in a disassembled state,
3 is a side view of the tip of the boom 1, FIG. 4 is a side view of the same, FIG. 5 is a side view of the tip of the boom 1 to which a conventional arm bracket plate 5 ′ is attached, and FIG. 6 is a rear view of the front half of the boom 1. 7 is a rear view of the second half, FIG. 8 is a rear view of the second half, FIG. 9 is a side view of the second half of the boom 1 supported by an excavation work vehicle, and FIG. 10 is a rear view of the second half. 11 is a partial rear view of the boom 1 showing the welded structure of the piping clamp seat 11, FIG. 12 is a front sectional view of the piping clamp C, FIG.
3 is a partial rear view of the boom 1 showing a welded structure of the pipe clamp portion 11 capable of fixing the grease hose 15, FIG.
Is a clamp C for piping that can fix the grease hose 15.
16 is a front cross-sectional view showing the retaining structure of the pivot pin 22 by the washer 27 at the pivot support portion of the arm base end boss 17a to the arm bracket plate 5, 5. FIG.
Is a front sectional view showing a retaining structure by the C-shaped retaining ring 28, FIG. 17 is a front sectional view showing a retaining structure in which a shim 29 is added to the structure of FIG. 16, and FIG. 18 is a conventional arm bracket plate 5.5. FIG. 19 is a front cross-sectional view showing a retaining structure of the pivot pin 22 in the pivot portion of the arm base end boss 17a only by the retaining bolt 24, and FIG. 19 is a retaining structure by the conventional retaining member 30 and the retaining bolt 31. 21 is a front sectional view showing the same, FIG.
Is the same as the conventional anti-rotation plate 5Lb and retaining bolt 3
22 is a front sectional view showing a retaining structure according to FIG. 2, FIG. 22 is a side view of the same, FIG. 23 is an overall perspective view of an excavation work vehicle, FIG. 24 is a plan view showing positions of respective levers near a seat, and FIG. FIG. 26 is a side view showing a lock mechanism of an arm operating lever, FIG. 26 is an electric circuit diagram showing an alarm mechanism when an electric system is abnormal when a working arm is operated, and FIG. 27 is an electric circuit diagram showing another embodiment.

As shown in FIG. 23, in the excavation work vehicle according to the embodiment of the present invention, the main body frame 20 is rotatably mounted on the crawler traveling device 21, and the boom bracket 19 is oscillated at the front end of the main body frame 20. The boom 1 is movably pivotally supported, and the base end of the boom 1 is pivotally supported at its upper end, and the base end of an arm 17 is pivotally supported at the tip of the boom 1.
A bucket 18 is pivotally supported at the tip of 7 to form an excavation work arm. A boom cylinder CY1 is disposed on the belly side of the boom 1, and the base end of the boom cylinder CY1 is pivotally supported on the boom cylinder tip bracket plate 9 that projects the tip of the piston rod on the belly side of the boom 1. are doing. The arm cylinder CY2 has a boom 1 at its base end.
Arm cylinder base end bracket plate 8 protruding from the back side of
The piston rod tip is pivotally supported on the arm cylinder tip bracket plate 17 provided near the base end of the arm 17.
It is pivoted to b. And the bucket cylinder CY3
Is connected to the bucket link 18a for pivoting the base end of the bucket 18 from the bucket cylinder base end bracket plate 17c protrudingly provided on the back side of the arm 17.

The present invention relates to the construction of the boom 1 shown in FIG. 1 in the working arm. First, the main part of the boom 1 is, as shown in FIGS. 1 and 2, the left and right side plates 2 facing each other.
2 (only the left side plate 2 is shown in FIGS. 1 and 2) and the opposing back plate 3 and abdominal plate 4 are welded together, and the left and right side plates 2 are the front side plates 2a. And rear side plate 2
It is divided into two parts of b and is welded to form one side plate 2. These plate materials 2 (2a, 2b), 3 and 4 are formed by cutting out original plates.

The longest of the working arms is the boom 1,
The side plate 2 is the longest of the side plates 2, the back plate 3, and the abdominal plate 4, which are the constituent plate materials of the boom 1. If the vehicle body and the working arm become larger, the side plate 2 will be cut out from the original plate and the yield will be exceeded. Therefore, as described above, it is necessary to divide the side plate 2 into the front side plate 2a and the rear side plate 2b, but in order to reduce the cost and facilitate the manufacturing, it is possible to cope with the increase in size and the decrease in size. The front side plate 2a is a common side plate member for both the large boom side plate and the small boom side plate so that even one of the front side plate 2a and the rear side plate 2b can be shared. That is, when constructing a large boom, the long rear plate 2b is attached to the front plate 2a, and when constructing the small boom, the short rear plate 2b is attached to the same front plate 2a.

Since a large stress is generated in the boom 1 at the time of work, increasing the number of welding parts by dividing the back plate 3 and the abdominal plate 4 in two leads to a decrease in strength. The back plate 3 and the abdominal plate 4 need only be shorter than the side plate 2. Therefore, even if the side plate 2 is divided into two parts due to an increase in the size of the working arm, it is formed of a single plate.

Next, the portion of the boom 1 on which the arm bracket plate 5 is attached will be described with reference to FIGS. 1 and 3 to 6. The left and right arm bracket plates 5, 5 for pivotally supporting the base end of the arm 17 are attached to each tip of the left and right side plates 2, 2 by welding. This portion has a large difference in strength between the portion where the hard arm bracket plate 5 is arranged and the portion where the side plate 2, the back plate 3 and the abdominal plate 4 of the soft boom 1 are arranged, and is therefore weak against the twisting force. Here, the arm bracket plate 5 in the present embodiment is provided with bulging portions 5a, 5a on the back side and the abdominal side as shown in FIG. 1 and FIG. The welded portions 6a and 6b of the tip rib 6 arranged on the back plate 3 and the abdominal plate 4 are covered so that they are not exposed to the outside.
In the conventional boom 1 in which the arm bracket plate 5 ′ having no bulging portions 5a and 5b provided on the back side and the abdominal side is attached, both welding portions 6a and 6b of the tip rib 6 are shown in FIG. Was exposed.

The tip rib 6 is a member which is bent in a "V" shape in side view to connect both tips of the back plate 3 and the abdominal plate 4,
In this way, the entire portion from the welded portion 6a to the back plate 3 to the welded portion 6b to the abdominal plate 4 is disposed between the arm bracket plates 5 and 5, so that the entire tip rib 6 serves as an arm. The bracket plates 5, 5 are reinforced and supported from the inside. Then, the arm bracket plates 5 and the tip ribs 6
That is, the arrangement part of is like a large box, and the stress resistance is enhanced.

The arm bracket plates 5, 5 can be shortened by the amount that the stress resistance is improved. Conventionally, a middle rib 7 at the tip is provided at a portion slightly closer to the base end side than the tip rib 6, both side plates 2 and 2 (in the boom 1 of this embodiment, the front side plates 2a and 2a to be precise) and the back plate. 3, it is arranged so as to be surrounded by the abdominal plate 4, but in the prior art, as shown in FIG. 5, in order to secure the strength of the arm bracket plate 5 ′, it is superposed on the portion where the rib 7 in the tip is arranged. The rear end of the arm bracket plate 5'has been extended to the position. That is, in a side view,
The arm bracket plate 5 ′ and the mid-tip rib 7 are polymerized to reinforce and support the arm bracket plate 5 ′ from the inside by the mid-tip rib 7. As described above, the extension of the rear end of the arm bracket plate 5 ′ limits the shortening of the arm bracket plate 5 ′, which impedes the weight reduction of the boom 1 as a whole. The arm bracket plate 5'is thick,
The larger the installation area, the more weight and cost increase.

In the tip portion of the boom 1 according to the present invention, as mentioned above, the bulging portions 5a and 5b are provided on the arm bracket plates 5 and 5 and the welding portions 6a and 6b of the tip rib 6 are provided.
Since the arm bracket plates 5, 5 are sufficiently reinforced and supported by the tip ribs 6, the stress resistance is ensured. Therefore, it is not necessary to overlap the arm bracket plate 5 with the middle rib 7 at the tip, and the arm bracket plate 5 is shortened to be smaller than the rib 7 at the middle of the tip as shown in FIGS. 1, 3, 4, and 6. The arm bracket plate 5 on the part near the tip
The rear end can be placed. Thus,
Since the arm bracket plate 5 can be made short by securing the stress resistance with the tip rib 6, it is possible to reduce the weight of the boom 1.
It contributes to cost reduction.

Further, the side plates 2 constituting the boom 1 are strengthened by increasing the strength of the mounting portion of the arm bracket plates 5, 5.
Thin plates can be used for the back plate 3 and the abdominal plate 4, and the boom 1 can be reduced in weight and cost. Further, even if the boom 1 itself is made lighter in this manner, the arm bracket plate 5 is shortened and made lighter, so that the weight balance before and after the boom 1 is not impaired.

Next, the pipe clamp seat 11 arranged on the back plate 3 of the boom 1 will be described. 1, 6 and 7
As described above, the piping clamp seat 11 is welded to an appropriate portion of the back plate 3. As shown in FIG. 12, a rubber clamp 12 and a metal clamp holding plate 13 are mounted on the bolt 14 with bolts 14 thereon.
・ The piping clamp C is constructed by screwing at 14. The welded part α of the pipe clamp seat 11 to the back plate 3 is
As shown in FIGS. 11 and 12, the two ends of the piping clamp seat 11 are conventionally welded to the upper surface of the back body 3 regardless of the contact portions of the side plates 2 and 2 with the back plate 3. Therefore, the strength of the welded portion against the torsional stress generated in the boom 1 was weak. In this embodiment, as shown in FIGS. 11 and 12, the side plate 2
Of the pipe clamp seat 11 to the back plate 3 is welded to the back plate 3.
The side plate 2 reinforces and supports the boom 1 to improve the resistance to the stress generated in the boom 1.

Another structure relating to the pipe clamp member C will be described. As shown in FIG. 1, FIG. 7, FIG. 13, FIG. 14, etc., one end of the piping clamp seat 11 disposed closest to the base end projects outward from the back plate 3, and grease is provided on the side end thereof. The hose terminal fixing member 11a is fixed. Boom 1
As shown in FIG. 9 and FIG. 10, a grease hose 15 for injecting grease into each pivotal support of the working arm is provided in parallel with the hydraulic hose H to the arm cylinder CY2, the bucket cylinder CY3, etc. on the back plate 3 of FIG. It is plumbed. Corresponding to this, the rubber clamp 12 of the piping clamp member C is provided with a hose hole 12a for guiding the grease hose 12, as shown in FIG. And the grease hose terminal fixing member 1
The terminal of the grease hose 15 is fitted and fixed in the grease hose terminal fixing member 11a in the pipe clamp C having 1a closest to the base end.

Conventionally, the grease hose 15 'as shown in FIG.
I connected it to the side plate 2 and fixed the terminal, but it looks bad and the side plate 2 has various indications.
The degree of freedom of piping position is limited. At a midway position of the boom 1 as shown in FIG. 9, if the size of the boom 1 is increased, this position becomes high and becomes inaccessible. The piping clamp member C having the grease hose terminal fixing member 11a is located at the most proximal position so that the grease hose terminal fixing member 11a can be reached, and the terminal of the grease hose 15 can be easily removed to remove the grease. The injection work can be performed.

Next, the structure of the boom lamp 16 will be described. As shown in FIGS. 8 and 9, the boom ramp 16 includes the left and right boom cylinder tip bracket plates 9 and 9 welded to the curved portion in the middle of the abdominal plate 4 of the boom 1.
It is arranged so as to be covered between and is protected. Further, although the side is covered with the boom cylinder tip bracket plate 9 in this way, the lamp irradiation surface is open, so that it is conventionally covered with a cover for protection. It was In this embodiment, as shown in FIGS. 8 and 9, the reinforcing rib 9a of the boom tip bracket plate 9 which is separate from the cover also serves as the cover of the boom lamp 16. That is, the reinforcing rib 9a connects between the left and right boom cylinder tip bracket plates 9 and 9 to reinforce and support both boom cylinder tip bracket plates 9 and 9, and an opening 9b is provided in this.
Boom lamp 16 has mounting portions 9c, 9c protruding inward. When mounting the boom lamp 16, both ends of the boom lamp 16 are pivotally supported by the mounting portions 9c and 9c so that the irradiation surface of the boom lamp 16 faces the opening 9b. 9a is the mounting member and cover of the boom lamp 16 as it is.

Further, for the boom lamp 16, a harness must be wired from the base end side. Conventionally, the boom lamp 16 is arranged on the one side plate 2, and the harness is also wired by a bundling band to a hydraulic hose that is piped on the back plate 3. Wiring is troublesome, looks bad, and lacks protection. In this embodiment, as shown in FIGS. 1 and 8, the boom ramp 16 is arranged between the boom cylinder tip bracket plates 9 and 9, whereas the boom lamp 16 is provided at one end of the abdomen plate 4 of the boom 1. ,
Welded boom lamp harness guide tube 10
The harness is inserted into the wiring for wiring, and it is difficult to see, the protection is improved, and the wiring work is easy only by inserting the harness into the guide tube 10.

Next, the retaining structure of the pivot pin 22 in the pivot portion of the base boss 17a of the arm 17 to the arm bracket plate 5, 5 at the tip of the boom 1 will be described with reference to FIGS. In addition, this structure for preventing the pivot pin from slipping off is used for other pivot parts of the excavation work arm, for example, the pivot part for the boom bracket 19 at the base end of the boom 1, the pivot part for the tip of the arm 17 at the base end of the bucket 18, and further. 23, the pivotal support portions of the base end and the tip of each cylinder CY1 to CY3, and FIG.
Excavation blade 47 provided in the illustrated excavation work vehicle
It can also be applied to the base end pivot part (also the pivot part of the hydraulic cylinder for this vertical rotation). Further, it can be applied to all structures in which the boss is pivotally supported between the left and right two brackets by the pivot pin regardless of the excavation work arm or the excavation work vehicle.

First, a conventional retaining structure for the pivot pin 22 will be described with reference to FIGS. 18 to 22. Basically, FIG.
As described above, one end of the pivot pin 22 is only fitted and inserted into the right arm bracket plate 5R, and the washer 23 is welded to the other end.
The left arm bracket plate 5L on the side where the other end is inserted is screwed with a rotation stop bolt 24 on the outer surface. In this structure, in FIG. 18, the portion fitted into the right arm bracket plate 5R is in a substantially loose fit state, and the pivot pin 22 is rotatable in the shaft hole of the right arm bracket plate 5R. There is. Therefore, it is only the rotation stop bolt 24 that locks the washer 23 to the left arm bracket plate 5L to prevent the rotation of the pivot support pin 22. The pulling force of the pin 22 causes the retaining bolt 24 to be sheared and the pivot pin 22 to rotate freely. In the worst case, the right arm bracket plate 5R
As a result, the end of the pivot pin 22 comes off.

Therefore, in order to strengthen the detent of the pivot pin 22, conventionally, the structure shown in FIGS. 19 to 22 has been used. First, in FIGS. 19 and 20, on the outer side of the left arm bracket plate 5L, a detent plate member 30 is laid over the washer 23, and two detent bolts 31 and 2 are provided at both ends of the detent plate member 30. At 31, a screw is fixed to a bolt seat 5La projecting from the left arm bracket plate 5L.
That is, the washer 23 of the left arm bracket plate 5L is prevented from rotating by the rotation stopping plate member 30, and the fixing strength of the rotation stopping plate member 30 to the left arm bracket plate 5L is increased. With this structure, the anti-rotation effect is improved, but the anti-rotation plate material 30 and two bolts are required,
An increase in the number of parts causes an increase in cost.

21 and 22, the detent bolts are not used in the left arm bracket 5L.
That is, although the pivot pin 22 is rotatable within the shaft hole of the left arm bracket plate 5L, instead of the pivot pin 2,
2 In order to restrict the rotation of the washer 23 ′ fixed at the tip, the washer 2
In the vicinity of 3 ', a rotation stop plate member 5Lb is projected from the left arm bracket plate 5L. This will prevent the pivot pin 22 from turning, but unlike bolting,
The axial movement of the pivot pin 22 cannot be restricted. That is, in this state, the pivot pin 22 slides in the axial direction (left side in FIG. 21), and the arm bracket plate 5
It may fall off more. Therefore, on the outside of the right arm bracket plate 5R, a retaining bolt 32 (which may be a split pin) is provided through the pivot pin 22 in the radial direction so that the pivot pin 22 moves in the axial direction. However, the retaining pin 32 (or the split pin) is not caught by the right arm bracket plate 5R and the pivot pin 22 does not fall off.

However, in this structure, the retaining bolt 3
If 2 is used, the screw thread is easily crushed and there is concern about reuse. Also, when the split pin is used, it is easy to lose it when it is pulled out, and it is easily deformed, so there is concern about reuse.

The pivot pin 22 shown in FIGS.
The pivot support structure adopts a retaining structure that solves such a problem. First, in all of FIGS. 15 to 17, the detent of the pivot pin 22 (and the washer 23 fixed to this) on the left arm bracket plate 5L is fixed to one detent bolt 24 as in the case of the conventional FIG. Since the washer 23 is screwed to the left arm bracket plate 5L, the cost is low. Then, in the right arm bracket plate 5R, a washer 27 is screwed to the right end of the pivot pin 22 in FIG. 15, and in FIG. As a structure in which the C-shaped retaining ring 28 is provided in a protruding manner, it is prevented from coming off from the right arm bracket plate 5R.

Further, in FIG. 17, the C-shaped retaining ring 28 is also shown.
And a shim 29 is provided between the C-shaped retaining ring 28 and the right arm bracket plate 5R so that the pressure contact force between the pivot pin 22 and the right arm bracket plate 5 can be adjusted. . In addition, the arm base end boss 17 into which the pivot pin 22 is loosely fitted
A bush 25 and a dust seal 26 are internally fitted in a so as to be annularly mounted on the pivot pin 22, but a fitting groove is fitted to the pivot pin 23 for annularly mounting a C-shaped retaining ring 28. When the pivot pin 23 is attached and detached, the dust seal 26 may be damaged when the fitting groove comes into contact with the dust seal 26. Therefore, in the pivot pin 22 of FIG. 17, the annular portion of the C-shaped retaining ring 28 is provided not with a groove but with a step portion 22a so that the dust seal 26 is not caught when it comes into contact with the dust seal 26.

Finally, referring to FIGS. 23 to 27, an abnormality alarm mechanism of the electric system when the work arm is operated will be described. First, as shown in FIGS. 23 and 24, a cylinder CY for driving the work arm of the boom 1, the arm 17 and the bucket 18
1 to CY3, and further, a swing cylinder (not shown) for swinging and driving the boom bracket 19 includes work arm operating levers 34L and 34 arranged on the left and right in front of the seat 33.
Operated by R. Of these, the left work arm operating lever 34
L is disposed on the operation box 36 on the left side of the seat 33, and the lock lever 35 is projected from the front part of the operation box 36 at the front position of the left work arm operation lever 34L. There is. Incidentally, in FIG. 24, 37 indicates the position of the starter switch 37.

In the operation box 36, as shown in FIG. 25, a base end of a lock lever 35 is pivotally supported so as to be vertically rotatable, and a lever lock switch 38 is arranged near the base end pivotally supporting portion. Has been done. When the lock lever 35 is pulled up to the X position, the base end portion of the lock lever 35 presses against the lever lock switch 38 to turn off the switch (OFF when pressed, ON when not pressed). ). Hydraulic cylinders CY1 to CY3 for driving the working arm
An electromagnetic solenoid 39 (shown in FIG. 26 and FIG. 27) for supplying pilot pressure is provided for the hydraulic circuit to the engine, etc., which is set to supply pilot pressure oil when energized and is not energized. At times, the pilot pressure supply is stopped and the hydraulic cylinders CY1 to CY3 cannot be driven,
The work arm cannot be operated. The lever lock switch 38 deenergizes the electromagnetic solenoid 39 when the lever lock switch 38 is OFF, that is, when the lock lever 35 is pulled up to the X position, the working arm driving hydraulic system becomes inoperable. It is possible to avoid a situation in which the work arm is moved by mistakenly pressing the work arm operation levers 34L and 34R when the work arm is not operated.

Also, the lock lever 3 pulled up to the X position
Even if 5 is rotated by mistake, it will lead to a malfunction of the working arm. Therefore, as shown in FIG. 25, while the lock lever 35 is pulled up, the operation box 36 and the lock lever 35 can be rotated to the Y position so that neither the work arm operation lever 34L nor the lock lever 35 can be operated.

Now, in the state where the lock lever 35 is released, as long as the electric system is normal and the electromagnetic solenoid 39 maintains the energized state, the work arm operating levers 34L.
Although the work arm can be driven by 4R, if the work arm cannot be driven in this state, the cause of failure is
There are two types of failures: hydraulic system failure and electrical system failure. This is because if the electric system fails, the electromagnetic solenoid 39 is de-energized and the pilot pressure is not supplied.
(The electromagnetic solenoid for pilot pressure supply is also available in a type that can supply pilot pressure without electricity. In this case,
If the working arm cannot be driven during work, it can be identified as a failure of the hydraulic system. On the other hand, even if the electric system fails during work, the electromagnetic solenoid remains de-energized from the beginning,
The pilot pressure oil supply to the hydraulic system for driving the working arm is maintained, and the driving of the working arm is continued. However, in this case, there is a problem that the failure of the electric system is not noticed during the work. Therefore, in the present embodiment, the electromagnetic solenoid 3 described above is used.
As shown in FIG. 9, the pilot pressure can be supplied when energized. )

If the cause of the failure cannot be immediately identified, the normal recovery will be delayed. Therefore, if the electromagnetic solenoid 39 is de-energized when the lock lever 35 is released (when the lever lock switch 38 is ON), it is determined that it is due to a failure of the electrical system, and a system is provided to issue an abnormal alarm at this time. .

The alarm system when the electric system shown in FIGS. 26 and 27 is abnormal will be described. In FIGS. 26 and 27, 40
Is a battery, 41 is a fuse, 42 is a current detector, 4
3 is a judging device, 43a is a power supply circuit, 43b is an operational amplifier,
43c is a NAND circuit, 44 is an abnormal alarm lamp, and 45 is an abnormal alarm buzzer.

In the electric circuit of FIG. 26, in order to detect disconnection of the electric system before the lever lock switch 38,
A separate switch (or sensor) 46 as a lever lock state detector is provided, and a circuit to the separate switch 46 is
The lever lock switch 38 and the separate switch 46 are arranged in parallel by branching from before the lever lock switch 38. In FIG. 27, disconnection of the electrical system after the lever lock switch 38 can be detected.

The electric circuit of FIG. 26 will be described. The lever lock switch 38 and the separately placed switch 46 are both turned ON / OFF by the movement of the lock lever 35, and are turned ON when the lock lever 35 is lowered to release the lock.
State. A harness is wired from the lever lock switch 38 to the − side of the operational amplifier 43b in the detector 43 through the electromagnetic solenoid 39 and the current detector 42, while in the detector 43, the harness of + of the operational amplifier 43b is provided.
Voltage is supplied to the side from the power supply circuit 43a. Here, even if a disconnection occurs between the fuse 41 and the lock lever switch 38 connected thereto, the operational amplifier 43
A voltage is supplied from the power supply circuit 43a to the + side of b, but the electromagnetic solenoid 39 is de-energized, and the voltage on the + side of the operational amplifier 43b becomes higher than the voltage on the-side. It is output to the a side of the NAND circuit 43c. On the other hand, the separate switch 46 is turned on when the lock lever 35 is lowered, and the NAND circuit 4
An output is made on the b side of 3c. NAND circuit 43c
The output becomes 0 only when the output is made to both sides of a and b, whereby the abnormality alarm lamp 44 is turned on and the abnormality alarm buzzer 45 is sounded.

In the electric circuit of FIG. 27, the fuse 4
No separate switch 46 is provided which can determine the disconnection between the 1 and lever lock switch 38, and the disconnection can be detected after the lever lock switch 38. That is, the harness h is branched immediately after the lever lock switch 38, and a voltage is supplied to the b side of the NAND circuit 43c in the detector 43. If a disconnection occurs from the branch point of the harness h immediately after the lever lock switch 38, an output is made to both sides a and b of the NAND circuit, the output from the NAND circuit becomes 0, and the abnormality alarm lamp 44 and The abnormal alarm buzzer 45 gives an abnormal alarm.

[0045]

Since the excavation work arm is constructed as described above, the present invention has the following effects. First, since it is configured as in claim 1, not only is the entire rib that connects the back plate and the abdominal plate covered with the arm bracket plate at the tip of the boom to improve the appearance, but the rib also forms the arm bracket plate. Since it is reinforced and supported, it is possible to strengthen the resistance to torsional stress.Therefore, it is not necessary to extend the rear end of the arm bracket plate to the overlapping part with the middle rib of the boom tip, and the arm bracket plate can be shortened. Contributes to weight reduction and cost reduction of the boom. In addition, by improving the strength of the arm bracket plate installation part, it is possible to use thin plates for the side plate, back plate, and abdominal plate that make up the boom, which contributes to the weight reduction of the boom as a whole and the weight of the arm bracket plate itself. Therefore, particularly in the swing work vehicle, the boom is thus reduced in weight and the front-rear weight balance is not lost.

Next, according to the second aspect, the side plate of the boom is divided into two parts, so that even if the side plate becomes longer as the boom becomes larger, each side plate divided into two parts is dimensioned. By using any of them as a member common to the long boom and the short boom, it is possible to reduce the cost and facilitate the manufacturing. Further, the back plate and the abdominal plate are shorter than the side plates, and can be configured as a single plate even if the size is increased, and the strength of the boom can be secured by not providing the welding portion.

Further, in the pipe clamp seat, the welded portion of the boom to the back plate overlaps with the contact portion of the side plate to the back plate, so that the welded portion is reinforced and supported by the side plate. Therefore, it is possible to withstand torsional stress.

Further, in the pivotal support structure by the pivotal pin, which is applied to the pivotal support portion of the base end of the arm to the boom tip, for example, by constructing as in claim 4, the rotation stop structure of the pivotal pin itself. Is simple in that the washer fixed to the pivot pin is screwed to the bracket plate with one bolt for preventing rotation, and the number of parts is small and the cost is low. On the other hand, in order to compensate for this fragile detent structure, the washer is screwed at the other end of the pivot pin and the C-shaped retaining ring is attached to prevent it from slipping off, preventing the pivot pin from falling off. It Further, unlike the conventional retaining bolts and split pins, the screwing of the washer as the retaining stopper and the ring arrangement of the C-shaped retaining ring are unlikely to be deformed, and they can be reused at low cost. From the above, it is possible to prevent the pivot pin from falling off at low cost,
This can be used not only for excavation work arms but also for all other things having a similar pivot structure.

[Brief description of drawings]

FIG. 1 is a side view of a boom 1 according to the present invention.

FIG. 2 is a side view showing a state in which the boom 1 is disassembled into a front side plate 2a, a rear side plate 2b, a back plate 3 and a belly plate 4 which are basic constituent plate members.

FIG. 3 is a side view of the tip of the boom 1.

FIG. 4 is likewise a ventral view.

FIG. 5 is a side view of the tip of the boom 1 to which a conventional arm bracket plate 5 ′ is attached.

FIG. 6 is a rear view of the front half of the boom 1.

FIG. 7 is a rear view of the latter half of the same.

FIG. 8 is likewise a ventral view of the latter half.

FIG. 9 is a side view of the rear half of the boom 1 supported by the excavation work vehicle.

FIG. 10 is a rear view of the latter half of the same.

FIG. 11 is a partial rear view of the boom 1 showing the welded structure of the piping clamp seat 11.

FIG. 12 is a front sectional view of a pipe clamp C.

FIG. 13 is a partial rear view of the boom 1 showing the welded structure of the piping clamp portion 11 that enables the grease hose 15 to be fixed.

FIG. 14 is a front cross-sectional view of a piping clamp C capable of fixing the grease hose 15.

FIG. 15 is a front cross-sectional view showing a retaining structure of a pivot support pin 22 by a washer 27 in a pivot support portion of an arm base end boss 17a to an arm bracket plate 5.5.

FIG. 16 is a front sectional view showing a retaining structure of a C-shaped retaining ring according to the same manner.

17 is a front sectional view showing a retaining structure in which a shim 29 is added to the structure of FIG.

FIG. 18 is a front cross-sectional view showing a conventional retaining structure of only the rotation stop bolt 24 of the pivot pin 22 in the pivot support portion of the arm base end boss 17a to the arm bracket plate 5;

FIG. 19 is a front cross-sectional view showing a retaining structure of a conventional detent member 30 and a detent bolt 31 of the same.

FIG. 20 is a side view of the same.

FIG. 21 is a front cross-sectional view showing a retaining structure using a conventional retaining plate 5Lb and retaining bolts 32.

FIG. 22 is a side view of the same.

FIG. 23 is an overall perspective view of an excavation work vehicle.

FIG. 24 is a plan view showing an arrangement position of each lever near a seat.

FIG. 25 is a side view showing a lock mechanism of a work arm operating lever.

FIG. 26 is an electric circuit diagram showing an alarm mechanism in the event of an abnormality in the electric system during operation of the work arm.

FIG. 27 is an electric circuit diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 boom 2 side plate 2a front side plate 2b rear side plate 3 back plate 4 belly plate 5 arm bracket plates 5a and 5b bulging part 5L left arm bracket plate 5R right arm bracket plate 6 tip rib 6a and 6b welding part 7 tip middle rib 11 piping Clamping seat α Welding part 17 Arm 17a Arm base end boss 22 Pivot pin 22a Step 23 Washer 24 Anti-rotation bolt 25 Bushing 26 Dust seal 27 Washer 28 C-type snap ring 29 Shim

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiharu Tanizono 1-32 Chayamachi, Kita-ku, Osaka-shi, Osaka Yanmar Diesel Co., Ltd.

Claims (4)

[Claims] 1. In a structure in which an arm bracket plate is attached to each tip of the left and right side plates of the boom at the tip of the boom of the excavation work arm, the entire rib connecting the both ends of the back plate and the abdominal plate of the boom is provided in the arm. An excavation work arm structure characterized in that it is covered with a bracket plate, and a middle rib of the boom tip is arranged between both side plates of the boom in a non-overlapping portion of the arm bracket plate. 2. In a boom structure of an excavation work arm constructed by welding a back plate, a belly plate and left and right side plates, the back plate and the abdominal plate are one plate, and each of the left and right side plates is divided into two parts. An excavation work arm structure characterized in that 3. In a structure in which a pipe clamp seat is welded to a back plate of a boom of an excavation work arm, a welding portion of the pipe clamp seat is overlapped with a contact portion of the left and right side plates of the boom with the back plate. An excavation work arm structure characterized in that 4. A structure in which a boss provided at each portion of an excavation work arm is pivotally supported by loosely fitting a pivot pin between left and right bracket plates, and a washer is fixedly provided at one end of the pivot pin to form a single piece. It is characterized in that it is screwed to one bracket plate with a rotation-preventing bolt, and a washer is fixed to the other end or a retaining ring is attached to the other end to prevent the bracket plate from coming off from the other bracket plate. Excavation work arm structure.