JP2000291043A - Power shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machine having a high stability which permits an operator to watch the bucket without twisting his body considerably at the time of offset of the excavation work apparatus. SOLUTION: An excavation work apparatus 22 is fixed with a shaft at the rear end portion of a boom 1 of a boom bracket 4 and supported in a sideward offset possible manner through 4-node links constituted with a pair of fulcrum shafts provided at an upper slewing body and a first link 5 and a second link 6 fixed with a pair of fulcrum shaft provided at the boom bracket 4, and a frame 19 as a base portion of the component such as a operator's cab 16 provided on the upper slewing body 10 is formed to a shape equipped with a box- shaped space 10a opened forward. Inside the box-shaped space 10a, the first link 5 and second link 6 are fixed with a shaft and housed in a rotatable manner at a pair of fulcrum shafts of the upper slewing body 10, and an offset cylinder 15 operating the 4-node link is housed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a power shovel. In more detail, an upper revolving unit that pivots on a plane parallel to the traveling surface around a pivot axis on the lower traveling unit is provided, and the excavation work device is mounted on a boom bracket separate from the upper revolving unit. At the rear end of the boom, a pair of fulcrum shafts provided on the upper swing body and a pair of fulcrum shafts provided on the boom bracket are pivotally mounted so as to be vertically rotatable. The structure is supported so as to be offset laterally through a four-bar link constituted by links, and the excavation work device is preferably offset to the right or left side to correspond to the right or left gutter of the fuselage. The excavation work of the gutter can be performed from a safe viewpoint, and safety can be secured.
The present invention relates to a power shovel capable of reducing a minimum turning radius in a forward direction by setting a position at which a rear end portion of a boom of an excavation work device is axially attached to a distance from a turning center to be small.

[0002]

2. Description of the Related Art Conventionally, a relatively small power shovel, such as a boom swing type power shovel as shown in FIG. 8, has been widely used because it can suitably excavate a gutter. According to this relatively small excavator,
A boom bracket 32 that supports the excavating work device 22 so as to be rotatable in the vertical direction is mounted on a front part of the upper revolving unit 30 so as to be rotatable in a horizontal direction on a longitudinal axis pin 34. To excavate the gutter. Usually, the boom bracket 32 is rotated left or right,
The upper revolving unit 30 is turned to the right or left in the opposite direction, and excavation proceeds in the traveling direction of the lower traveling unit 10 of the power shovel. At this time, excavation work is performed in a state where the traveling direction and the center line of the excavation work device 22 are parallel.

[0003] In this comparatively small power shovel, how far a side excursion from the turning center A can be excavated depends on the magnitude of the turning angle of the boom bracket 32 and the turning center of the upper turning body 30. A is determined by the distance between A and the vertical pin 34 on which the boom bracket 32 rotates.
The swing center of the upper swing body 30 and the boom bracket 32
The distance from the vertical axis pin 34 at which is rotated is substantially determined by the size of the vehicle body, and clearly becomes the largest when rotated by 90 degrees in FIG. That is, as shown in FIG. 8, when the boom bracket 32 on which the excavation work device 22 is pivotally mounted is rotated 90 degrees left or right with respect to the upper revolving unit 30 by the swing cylinder 36 at the maximum, the upper revolving unit is rotated. 30 is turned to the right or left, which is the direction opposite to the direction of rotation of the boom bracket 32, so that the lower traveling body 10 and the excavation work device 22 are in a parallel state and the excavation work of the gutter is proceeded along the road. is there.

[0004]

However, when performing excavation work using the above-mentioned relatively small power shovel, the driver must use the driver's seat 3 fixed on the upper swing body 30.
In order to steer in front of the upper revolving superstructure 30 at 7, the operation at this time is performed by bending the neck or the body in the direction of the excavating work device 22. There is a problem that the body becomes tired more than necessary if such work continues. Further, the movement of the excavating work device 22 is set so as to be operated by the movement of the operation lever in accordance with the operation direction of each part.
Therefore, in the state of being bent by 90 degrees, an operation error is sometimes easily caused, an unexpected accident may occur, and there is a demand for a machine that can be safely operated.

For this reason, conventionally, a mechanism relating to a power shovel as shown in FIG. 9 or FIG. 10 has been proposed as a desktop idea. The revolving structure offset front device shown in FIG. 9 is a technology disclosed in Japanese Patent Application No. 7-252856. FIG. 9A is a side view illustrating the entire apparatus, and FIG. 9B is an enlarged plan view illustrating a main part of the front apparatus. According to this front device, the excavation work device 22 having a bucket, an arm, and a boom for performing excavation work is supported by the boom bracket 38, and the boom bracket 38 is connected to the upper revolving unit 40 via the pair of links 39a, 39b. Is connected to the front end 42a of the frame 42 of FIG. That is, in the offset front device shown in FIG. 9, the excavation work device 22 is supported by the boom bracket 38 separate from the upper swing body 40, and the boom bracket 38 is provided with two fulcrum shafts 38a and 38b and the upper swing body 40 Is provided with two fulcrum shafts 43a and 43b and a device capable of laterally offsetting the excavating work device through a so-called four-bar link formed by connecting a pair of links 39a and 39b with pins 45. According to this power shovel, it is possible to cope with a request to avoid twisting the neck or the body in the direction of the excavating work device 22.

The length of the pair of links 39a and 39b is inevitably determined in order to set the magnitude of the offset of the excavating work device 22 by the four-bar link to a predetermined size corresponding to the vehicle size. When a pair of links 39a, 39b having a predetermined offset amount is supported by the front end 43 of the upper swing body 40 by the front device, when the excavation work device 22 is positioned at the center without offsetting, , Excavation work equipment 22
Boom bracket 38 which is a part for attaching the boom 1
The position of the boom foot protrudes largely forward ignoring the vehicle body balance, and there is a problem that stability cannot be secured. Further, in order to ensure the stability, the pair of links 39a and 39b is set to be short, and the magnitude of the offset cannot be satisfied, so that it has not yet been put to practical use.

On the other hand, a hydraulic power shovel shown in FIG. 10 is disclosed in Japanese Utility Model Application No. Sho 50-15614.
According to this, in order to ensure the stability, the link configuration is the same as that of the prior art of FIG. 9, but the four-bar link structure is provided on the upper revolving unit 50, and the position of the boom foot is retracted to stabilize. Is secured. The range of the offset of the excavation work device 22 is only the center and the right side, and the excavation work device 22 has a structure that cannot be offset to the cab 16 side (left side) because it interferes with the cab 16.

That is, in the prior art power shovel shown in FIG. 9, the problem of stability is solved because the offset mechanism of the excavating work device 22 provided at the front end of the upper swing body 50 protrudes forward. There is a need to. Also,
In the power shovel of the related art shown in FIG. 10, it is necessary to solve the problem that the range of the offset of the excavation work device 22 is limited to the center and the right, and the offset cannot be performed to the left, and the workability cannot be improved. Further, in the boom swing type excavator, a machine in which a turning radius of a rear end of the upper revolving structure 50 is suppressed within a vehicle width or to a predetermined allowable size,
It is very useful because the excavated earth and sand can be loaded into a bucket and turned around to load the earth and dump into a dump without using a nerve in the rear. Normally, work is performed with the rear end side defined as the narrow side of the site. However, depending on the situation at the site and the content of the operation, a turning operation in a predetermined angle range facing only in the same direction may not be sufficient. For this reason, there is a demand for improving the workability of the machine by making it possible to turn in any direction by minimizing the turning radius in the front as much as possible.

Accordingly, an object of the present invention is to firstly offset the excavation work device to the left and right gutter excavation postures, so that the operator can see the movement of the bucket without greatly twisting the body when offset. In this case, the driver's seat and the bucket can be placed in a preferable positional relationship, and the stability at that time can be secured at the same level as that of the boom swing type already accepted in the market. In addition, the minimum turning radius at the front can be reduced so that workability is good even in a narrow site. And, in order to suitably solve those problems, the excavation work device is mounted on a boom bracket separate from the upper revolving unit so as to be rotatable vertically at the rear end of the boom, A power shovel supported so as to be laterally offset via a four-bar link constituted by a pair of links that are pivotally mounted on a pair of fulcrum shafts provided on the body and a pair of fulcrum shafts provided on the boom bracket. In addition to the idea of a desk, it is to provide a practical and practical machine.

[0010]

In order to solve the above problems, the present invention has the following arrangement. That is, the power shovel according to the present invention is provided with an upper revolving structure that revolves on a plane parallel to the traveling surface around a revolving axis on the lower traveling structure, and is connected to attachments such as a boom, an arm, and a bucket in this order. And an excavation work device mounted on the upper revolving unit is rotatably mounted on a boom bracket separate from the upper revolving unit at a rear end of the boom so as to be vertically rotatable. In a power shovel supported so as to be laterally offset via a four-bar link constituted by a pair of links pivotally attached to a pair of fulcrum shafts provided on the boom bracket and a pair of fulcrum shafts provided on the boom bracket. A frame serving as a base of components such as a driver's cab provided on the upper revolving structure is provided in a shape including a box-shaped space having an open front, and a front space is provided in the box-shaped space. A pair of links are rotatably mounted on a pair of fulcrum shafts of the upper revolving structure and housed therein, and an offset cylinder for operating the four-bar link to offset the excavating work device is housed. And

Further, the distance between the pair of fulcrum shafts of the upper revolving structure to which one end of each of the pair of links is axially attached is the same as the distance between the other end of each of the pair of links. A line that is larger than the distance between the pair of fulcrum shafts of the boom bracket and that connects the pair of fulcrum shafts of the upper revolving structure passes through or near the revolving shaft center at which the upper revolving structure is revolved. This makes it possible to preferably perform the offset of the excavation work device, to turn the driver's seat at an angle that is easy for the driver to operate, and to further improve the stability of the machine.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing one embodiment of a power shovel according to the present invention. FIG. 2 is a left side view of the embodiment of FIG. 1, and FIGS. 3 and 4 are plan views showing a use state of the embodiment of FIG. FIGS. 5A and 5B are explanatory views of the structure of the upper swing body of the embodiment of FIG. 1, wherein FIG. 5A is a front view, FIG. 5B is a plan view, FIG. 5C is a left side view, and FIG. It is. Reference numeral 20 denotes a lower traveling body, which normally drives a crawler to travel a power shovel as shown in the figure. Reference numeral 10 denotes an upper revolving unit that revolves around a revolving axis A on the lower traveling unit 20 on a plane parallel to the traveling surface. That is, the upper revolving unit 10 is rotatably fixed by the revolving bearing 21 provided on the lower traveling unit 20 and can revolve around a point A which is a revolving axis orthogonal to the traveling surface.

As shown in FIG. 5, the lower part of the upper revolving unit 10 is a member constituting the entire main body so as to form a frame structure having a box-shaped space 10a with an open front F. A base member 11 provided in a shape, an upper member 12 serving as an upper part of the frame structure and provided in a planar shape, and the base member 11 and the upper member 12
Are formed in a box shape by the side plates 13 and 14 which are vertical members connecting them. Point A is the center of rotation of the upper swing body 10 and the axis of the swing bearing 21 as described above. Also, B and C indicate holes or positions where the first link 5 and the second link 6 which are a pair of links are pivotally supported so as to be rotatably supported. A pin 8 acting as a fulcrum shaft is inserted into this hole. The box-shaped space 10a opened forward of the frame structure extends from the front in the front-rear direction to a position range beyond the turning center A rearward.

The boom bracket 4 is a separate structure from the upper swing body 10 and is a rear end 1 of the boom 1 of the excavating work device 22.
The boom 1 is pivotally mounted on the shaft a. One end of the first link 5 is axially attached to one side B of the upper swing body 10 in the width direction by a pin 8 (fulcrum shaft), and the other end is axially attached to one side of the boom bracket 4 in the width direction by the pin 7. The upper revolving unit 10 is accommodated in a box-shaped space 10a having a frame structure in which the front of the upper revolving unit 10 is opened, and rotates on a plane parallel to the revolving surface of the upper revolving unit 10. The second link 6 has one end pivotally attached to the other side C in the width direction of the upper swing body 10 by a pin 8 and the other end pivotally attached to the other side in the width direction of the boom bracket 4 by a pin 7. The upper part of the revolving unit 10 is accommodated in a box-shaped space 10 a having a frame structure with an open front, and rotates on a plane parallel to the revolving surface of the upper revolving unit 10. In the present embodiment, a pair of links (the first link 5 and the second link 6) are in the state shown in FIG.
a.

In this embodiment, the width of the first link 5 and the second link 6 in the width direction between the positions B and C at which the first link 5 and the second link 6 are attached to the upper revolving unit 10 is the interval between the first and second links 5 and 6 (one pair). (A distance between a pair of pins 7 constituting the fulcrum shaft), and a line connecting B and C is located slightly behind the turning center point A in the front-rear direction. The offset cylinder 15 has a cylinder bottom side rotatably mounted on a connecting portion of the first link 5 near a side where the first link 5 is mounted on the upper swing body 10, and a cylinder rod side is mounted on the boom bracket 4. In this embodiment, in the state shown in FIG. 1, at least half of the offset cylinder 15 is housed in the box-shaped space 10a. The offset cylinder 15 operates as a drive device for offsetting the excavating work device 22 right and left through a link mechanism including the first link 5, the second link 6, the boom bracket 4, and the upper swing body 10.

The link mechanism of the present embodiment includes an upper
, The first link 5, the second link 6, and the boom bracket 4 to form a so-called four-bar link. In addition, the four-bar link is not a four-bar parallel link but an irregular length. In this embodiment, when the boom bracket 4 is located on the right side of the center line of the upper swing body 10 and does not interfere with the driver's seat 16 in the boom, the upper swing body 10
And become parallel. Also, as shown in FIG. 3, when the boom bracket 4 is offset to the left, the boom bracket 4 is slightly rotated right and protrudes to the left front of the driver's seat 16.
Then, as shown in FIG. 4, when the boom bracket 4 is offset to the right, the boom bracket 4 turns slightly to the left and approaches the turning center of the upper turning body 10 in the front-rear direction and is located on the right side of the driver's seat 16. Link ratio.

The configuration of the present invention will be described below in comparison with the prior art. An excavation work device 22 is supported by the rear end of the boom 1 being pivotally mounted on a boom bracket 4 that is separate from the upper revolving structure 10. The boom bracket 4 is provided with two fulcrums and the upper revolving structure is provided with two fulcrums. It is the same as the prior art that a fulcrum is provided to connect the first link 5 and the second link 6 with the pins 7 and 8, respectively, so that the excavating work device 22 can be laterally offset via a so-called four-bar link. , But differs in the following points. In the present invention, the frame 1 which is a lower part (base) of a floor on which the components such as the cab 16 and the hydraulic oil tank 17 are provided in the upper revolving unit 10
9 is provided in a structure having a box-shaped space 10a in which the front F of the fuselage is opened. Then, two fulcrum shafts (pins 7) are provided on the boom bracket 4 and two fulcrum shafts (pins 8) are provided on the upper rotating body 10 to connect the first link 5 and the second link 6 with the pins 7 and 8, respectively. Then, a cylinder 15 is disposed between the first link 5 and the boom bracket 4, and is housed in the frame 19 of the upper swing body 10 having the box-shaped space 10a. That is, the upper rotating body 10
Is provided in a frame structure having a box-shaped space 10a with an open front F, so that even if there is a driver's seat 16, the link device is housed in a frame 19 below the driver's seat 16. It is in the form. For this reason, the excavation work device 22 is suitably offset to the left and right sides of the fuselage, and the excavation of the gutter can be greatly different from the related art.

The positions B and C at which the first link 5 and the second link 6 are attached to the upper revolving structure 10 are wider than the intervals at which the first link 5 and the second link 6 are attached to the boom bracket 4 in the width direction. , C are positioned so as to pass near the turning center axis (point A). For this reason, the first link 5 and the second link 6 can be provided without difficulty compared to a machine in which a link structure is provided in front of the body as in the related art. Thereby, the distance L1 from the turning center of the boom foot 4a can be suitably set to the same distance as that of a normal boom swing type excavator, and stability can be secured. Also,
Since the shaft attachment positions B and C are suitably provided at the positions distributed to both sides in the radial direction of the turning center A, the load acting on the excavation work device 22 can be dispersed in a well-balanced manner.
Rigidity can be secured even with a frame structure. In addition, in order to reduce the minimum front turning radius FR (see FIG. 6), the distance from the turning center of the boom foot 4a of the boom bracket 4 where the rear end of the boom 1 is to be axially attached is determined by changing the overall layout. It differs greatly in that it can be set to a small desired distance L4.

Both ends are fixed to an upper plate (upper surface member 12) and a lower plate (base member 11) of the housing constituting the box-shaped space 10a, and are supported vertically (perpendicular to the turning surface). The first link 5 and the second link 6 are
At one end, it is suitably mounted on the upper swing body 10.
According to the box-shaped housing structure, the pins 8 can be strongly supported by dispersing the load so as to withstand a high load. For this reason,
The first link 5 and the second link 6 which are pivotally mounted on the pin 8
However, it is strongly supported, and the durability as a construction machine can be secured.

Next, the use state of the above embodiment will be specifically described with reference to the drawings. First, as shown in FIG. 1, in a state where the offset cylinder 16 is held at a substantially intermediate position, the reference lines (center lines) of the excavating work device 22 and the boom bracket 4 are the upper revolving unit 10 and the lower traveling unit 20.
Is parallel to the reference line (center line M extending in the front-rear direction), and is eccentric to the right side opposite to the driver's seat 16 by a distance W1 that does not interfere with the driver's cab 16 even when the boom 1 is raised. In this state, the distance between the turning center A and the boom foot 4a of the boom bracket 4 in the front-rear direction is L1.

FIG. 3 shows a state in which the offset cylinder 15 is contracted. When the offset cylinder 15 is rotated to contract between the first link 5 and the boom bracket 4, the boom bracket 4 is moved to the left side of the cab 16 by the action of the four-bar link. And the excavation work device 22 is swung to the right. Then, the upper revolving unit 10 is turned to the left, and the center line M of the lower traveling unit 20 and the center line of the excavator 22 are parallel to each other. From the turning center A in this state, the boom foot 4a
Is L2, and the distance of the offset of the excavating work device 22 is W2.

FIG. 4 shows a state in which the offset cylinder 15 is extended. By rotating the offset cylinder 15 so as to widen the space between the first link 5 and the boom bracket 4, the boom bracket 4 is operated on the right side by the action of the four-bar link. It has moved to the side of the chamber 16 and the excavation work device 22 has been swung to the left. Then, the upper revolving unit 10 is turned to the right, and the center line M of the lower traveling unit 20 and the center line of the excavator 22 are parallel. In this state, the distance from the turning center A to the boom foot 4a is L3, and the offset distance of the excavating work device is W3. This state is the position of the maximum offset of the excavation work device 22 for the gutter excavation on the right side.

FIG. 6 shows a state in which the excavating work device 22 is folded so that the upper swing body 10 can make a very small swing. FIG. 6A is a plan view, and FIG. 6B is a side view.
At this time, the excavation work device 22 is in the right offset state,
The magnitude of the offset is such that the cab 16 and the bucket 3 do not interfere with each other and the bucket 3 does not protrude from the vehicle width. That is, the boom bracket 4 moves
And is offset to a position where the distance between the boom foot 4a becomes L4. At the position of the boom foot 4a (boom bracket 4), as shown in FIG. 6, the boom 1 is raised to a form in which the excavation work device 22 is housed in the upper part of the vehicle body as in the case of the micro turning machine.
A forward minimum turning radius FR comparable to the performance of a micro turning machine can be obtained, and the performance usage can be improved.

In the present invention, a frame 19, which is a lower part of a floor on which components such as a driver's seat 16 and a hydraulic oil tank 17 are provided, is provided on a front portion of the upper revolving unit 10 with a box having a front F opened. It has a structure with a shaped space.
Thus, in the structure of the frame 19, the first link 5,
By storing the device structural components such as the second link 6 and the offset cylinder 15, the excavation work device 22 can be offset to the left and right.

Also, as described above, in the present embodiment, the first link 5 and the second link 6 are larger than the interval at which one end of each of the first link 5 and the second link 6 is axially attached to the boom bracket 4. The interval at which the other end of the link 6 is pivotally attached to the upper swing body 10 is larger. Regarding the position in the front-rear direction where the first link 5 and the second link 6 are axially attached to the upper swing body 10, a line connecting a pair of support shaft positions (axial attachment positions) B and C of the upper swing body 10 is The upper revolving unit 10 is configured to pass through or near the revolving center A. As a result, the four-bar links can be suitably arranged, and the desired position and direction of the boom bracket 4 can be set without difficulty. Boom foot 4a of excavating work device 22
The distance from the turning center A of the lower traveling body 20 is
In a normal posture parallel to the above, the distance can be set to be equal to that of the conventional boom swing type excavator, so that stability can be secured.

When the excavator 22 is offset to the left, the boom bracket 4
The bucket 3 can be directly viewed by allowing the left gutter to be excavated in a form in which the bucket 3 is protruded. Therefore, there is no fatigue such as bending the neck or body. Also, when the excavator 22 is offset to the right, the field of view is secured by the same symmetrical movement. In the embodiment shown in FIG. 6, the position of the boom foot 4a of the boom bracket 4 is shifted from the center of rotation at the limit position W4 where the bucket 3 does not interfere with the cab 16 at the right offset of the excavating work device 22 and does not come out of the vehicle width. The excavation work device 22 can be stored in the upper part of the vehicle body as in the case of the ultra-small turning specification machine by reducing the distance L4. As a result, a forward minimum turning radius FR comparable to that of the ultra-small turning specification machine can be obtained, and the performance specifications can be improved.

The position of the boom bracket 4 as described above,
The relationship between the directions is determined by the design intention, but when the four-bar link moves and changes to the form of left or right offset, the relative angle of each link is, according to the reference book, "90 degrees. The range of ± 45 degrees is ideal, and the operation and transmission of force are easy. ”This value is 90 degrees, which is the same as the angle at which the boom 1 and the arm 2 are rotated by the cylinder. The degree is ± 70 degrees. In addition, the relationship between the position and direction of the boom bracket 4 set according to the design intention described above is determined for each of the links (the first link 5 and the second link 6) on the limited upper revolving structure 10.
In order to set the relative angle of the first link 5 and the second link 6 in the range of the limit, the line connecting the shaft attachment positions B and C in the front-rear direction of the position where the first link 5 and the second link 6 are attached to the upper swing body 10 is the upper part. There is a background that cannot be established unless it is configured to be located near the turning center A of the turning body 10. In order to ensure the durability of each component as a construction machine, it is necessary to cope with the design within a range where power and force can be transmitted without difficulty, and the above positional relationship is an important factor.

In the embodiment shown in FIG. 6, two links (third links 23) operated by the boom cylinder 18 are provided so that the vertical rotation angle of the boom 1 can be increased.
And a link mechanism having a fourth link 24). The principle of the link mechanism will be described with reference to FIG. FIG. 7A is a side view showing a state in which the boom 1 is pulled up so as to fold the excavating work device 22, and FIG. It is a side view which shows the state turned to. In the configuration of the link mechanism shown in FIG.
Arm 2 and boom 1, bucket 3 and arm 2
The excavation work device 22 is shown in which the boom 1 is rotatably mounted at one end to the boom foot portion 9 of the base body so that the boom 1 can be operated in the front. However, in the embodiment shown in FIG. The upper revolving unit 10 is provided with a bracket 4 and a pair of links (a first link 5 and a second link 6).

As shown in FIG. 7, reference numeral 18 denotes a boom cylinder. One end of the boom cylinder is rotatably mounted on a middle part of the boom 1 to rotate the boom 1 in the vertical direction. Reference numeral 23 denotes a third link, one end of which is rotatably mounted near the one end of the boom 1 and at a position on the halfway side of the boom 1, and the other end of the boom cylinder 18 rotates at the other end. It is freely pivoted. Reference numeral 24 denotes a fourth link, one end of which is rotatably mounted at a position forward and lower than a position at which one end of the boom 1 of the boom foot portion 9 is mounted, and a second end of which is provided at the other end. The other end of the three link 23 is rotatably mounted on the shaft. In the configuration of the link mechanism shown in FIG. 7, the other end of the third link 23, the other end of the fourth link 24, and the other end of the boom cylinder 18 are coaxially mounted on a shaft. In the embodiment shown in FIG. 7, the position of the other end of the third link 23 to which the other end of the fourth link 24 is axially mounted, and the position of the boom cylinder 18
The other end of the third link 23 to which the other end of the third link 23 is axially attached is different.

The vertical rotation angle of the boom 1 can be increased by the link mechanism including the third link 23 and the fourth link 24 mounted at the suitable positions as described above. Therefore, it is possible to extend the driving range in both the folding direction and the excavation direction of the boom 1 and perform a very small turning, thereby improving the folding performance and the excavation work performance. As described above, various preferred embodiments of the present invention have been described. However, the present invention is not limited to these embodiments, and it goes without saying that many more modifications can be made without departing from the spirit of the invention. That is.

[0031]

According to the power shovel of the present invention, the excavation work device is supported by the boom bracket which is separate from the upper swing body, and the boom bracket is provided with two fulcrum shafts, and the upper swing body is provided with two fulcrum shafts. Is provided, and the first link and the second link are connected to each other to form a so-called four-bar link, and a power shovel having a device capable of laterally offset the excavating work device via the four-bar link is provided on a desk. It has become possible not only to devise but also to make it suitable for practical use.
That is, in the present invention, the portion of the upper revolving structure where the first link and the second link are pivotally attached has a frame structure having a box-shaped space with an open front, and the four-bar link is formed of the upper revolving structure. In the frame. For this reason, when the excavator is offset right and left, the operator can see the bucket without significantly twisting the body, and it can be a machine with good stability. It has a significant effect that performance can be improved. Further, by the frame structure having the box-shaped space of the upper swing body, the load applied via the first link and the second link can be appropriately dispersed and received in a well-balanced manner. Thus, according to the present invention,
This has a remarkable effect that durability as a construction machine can be suitably obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a power shovel according to the present invention.

FIG. 2 is a side view of the embodiment of FIG.

FIG. 3 is a plan view illustrating a use state in which the excavating work device is offset to the left in the embodiment of FIG. 1;

FIG. 4 is a plan view illustrating a use state in which the excavation work device is offset rightward in the embodiment of FIG. 1;

FIG. 5 is a structural explanatory view of the upper swing body of the embodiment in FIG. 1;

FIG. 6 is an explanatory diagram illustrating a state in which the excavator of the power shovel according to the present invention is turned upward and folded.

FIG. 7 is an explanatory view schematically illustrating a vertical turning mechanism of the boom.

FIG. 8 is a plan view illustrating a conventional boom swing type power shovel.

FIG. 9 is an explanatory diagram illustrating a conventional technique.

FIG. 10 is an explanatory diagram for explaining another conventional technique.

[Explanation of symbols]

 Reference Signs List 1 boom 2 arm 3 bucket 4 boom bracket 4a boom foot 5 first link 6 second link 7 pin 8 pin 10 upper revolving body 10a box-shaped space 15 offset cylinder 16 cab 17 hydraulic oil tank 18 boom cylinder 19 frame 20 lower part Vehicle 22 Excavation work device

Claims (2)

[Claims] An upper revolving structure is provided which revolves on a plane parallel to a running surface about a revolving axis on a lower traveling structure, and is connected to an attachment such as a boom, an arm, a bucket and the like in this order. An excavation work device is mounted on a boom bracket separate from the upper revolving structure so as to be rotatable in a vertical direction at a rear end portion of the boom, and a pair of excavating operation devices are provided on the upper revolving structure. A power shovel supported so as to be laterally offset via a four-bar link formed by a pair of links pivotally mounted on a fulcrum shaft and a pair of fulcrum shafts provided on the boom bracket. A frame serving as a base of components such as a driver's cab provided on the vehicle is provided in a shape including a box-shaped space opened at the front, and the pair of links are provided in the box-shaped space. Upper swing Excavators that of the pair of pivot shafts with is housed is rotatably journalled, characterized in that the offset cylinder for offsetting the excavating device actuates the four-joint link is housed. 2. The distance between a pair of fulcrum shafts of the upper revolving structure to which one end of each of the pair of links is axially attached is the same as that of the other end of each of the pair of links. A line that is larger than the distance between the pair of fulcrum shafts of the boom bracket and that connects the pair of fulcrum shafts of the upper revolving structure passes through or near the revolving shaft center at which the upper revolving structure is revolved. The power shovel according to claim 1, wherein: