JP2003034945A - Offset boom tape construction machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a stroke of a boom cylinder of a first boom greater and enhance performance, by protruding a mounting bracket for the boom cylinder forward. SOLUTION: The first boom 10 and a second boom 11 are coupled together in a horizontally oscillatable manner by a coupling pin 32. A rod mounting hole 34 of the mounting bracket 33 for the boom cylinder 15 is arranged on a side ahead of an axis A-A of the coupling pin 32 with respect to the longitudinal direction of the first boom 10 or in a position which is approximately identical to a position of the coupling pin 32. In addition, a tube 15A of the boom cylinder 15 is mounted in a tube mounting hole 8 on the side of a super structure 2, and a rod 15B is mounted in the hole 34. Thus, the boom cylinder 15 having the great stroke can be arranged between the holes 8 and 34, and the performance of an excavating depth, etc., can be enhanced along with the miniaturization of a front 9 including the first bloom 10, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset boom type construction machine such as a hydraulic excavator that is preferably used for excavating earth and sand.

[0002]

2. Description of the Related Art Generally, some construction machines such as hydraulic excavators use an offset boom type front which enables excavation work such as a gutter on the left side or the right side of a vehicle body. As such an offset boom type construction machine, for example, in order to secure the digging depth when digging a trench deep in the ground, three booms are installed on the left,
A hydraulic excavator configured to be connected so as to be swingable rightward is known (for example, Japanese Patent Laid-Open No. 11-256617).

An offset boom type hydraulic excavator according to this type of prior art has an upper revolving structure rotatably mounted on a lower traveling structure, and a front as a working device is provided on the front side of the upper revolving structure. ing.

This front is mounted on a swing frame of an upper swing body so as to be able to move up and down, and a first boom is swingable leftward and rightward on the tip side of the first boom. The attached second boom, the third boom attached to the tip end side of the second boom so as to be swingable in the left and right directions, and the upper and lower turnable portions at the tip end side of the third boom. It is composed of an attached arm and a bucket attached to the tip end side of the arm so as to be pivotable upward and downward.

Further, on the front, a boom cylinder, an arm cylinder, a bucket cylinder for operating the first boom, the arm, and the bucket in the upward and downward directions, respectively, and a second cylinder.
An offset cylinder that swings the boom to the left and right is provided.

A vertical connecting pin extending in a direction substantially perpendicular to the longitudinal direction of the first boom is provided between the first boom and the second boom, and at the tip end side of the first boom,
The second boom is configured to swing leftward and rightward about the vertical connecting pin.

A boom cylinder for raising and lowering the first boom upward and downward has its base end side pin-connected to a turning frame of the vehicle body, and the tip end side of the boom cylinder is
It is configured to be pin-coupled to a boom cylinder mounting bracket provided at a position closer to the revolving frame than the vertical connecting pin in the longitudinal direction of the first boom.

When excavating work with the hydraulic excavator, the second and third booms, the arm and the bucket are moved to the left or right side with respect to the first boom (offset) by operating an offset cylinder, for example.
Then, excavation work such as gutters is performed at this position. Further, when excavating a deep groove or the like, for example, by reducing the boom cylinder, the arm cylinder, or the like, and moving the front largely downward below the ground, it is possible to dig the groove deep in the ground in this state. .

On the other hand, for example, when performing the swinging motion of the upper swing body in a narrow work site, the boom cylinder, the arm cylinder, etc. are extended and the arms, buckets, etc. are moved to the vehicle body side in order to arrange the entire front in a small swing posture. While pivoting so as to fold, the first boom is largely swung upward.
As a result, the entire front is erected upward and has a small turning posture that fits within the turning radius of the upper turning body, so that, for example, even in a narrow work site, without colliding with surrounding obstacles,
A turning motion can be performed.

[0010]

By the way, in the above-mentioned prior art, for example, during the excavation work of a deep groove, the boom cylinder is contracted to the minimum position so that the first boom and the like are largely moved downward, whereby the excavation groove is deeply moved. To secure the depth of. In addition, for example, when the entire front is kept in a small turning posture, the boom cylinder is extended to the maximum position, so that the first boom is largely swung upward.

For this reason, in the prior art, the elevation angle of the first boom is raised when the first boom is lifted upward in a small turning posture and when the first boom is lowered downward during deep groove excavation. To make it possible to set a large value, increase the stroke between the boom cylinder's maximum extension and its minimum contraction,
As the boom cylinder, a long cylinder device is used.

However, if the boom cylinder is constituted by a long cylinder device, the first boom also needs to be formed long corresponding to the boom cylinder, which not only increases the weight of the first boom, but also increases the entire front. Becomes heavy and becomes heavy. Therefore, in the related art, it is necessary to configure the boom cylinder with a long and large-diameter cylinder device, which causes a problem of increased cost.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to use a boom cylinder having a large stroke without forming the first boom in a long size. It is an object to provide an offset boom type construction machine capable of reducing the size and weight of the entire front while ensuring a sufficient elevation angle.

[0014]

In order to solve the above-mentioned problems, the invention of claim 1 comprises a vehicle body capable of self-propelling and an offset boom type front mounted to the vehicle body. Are a first boom mounted on the vehicle body and moved up and down by a boom cylinder, and a second boom mounted on the tip end side of the first boom and swung left and right by an offset cylinder. ,
In an offset boom type construction machine including a work tool attached to the tip end side of the second boom, the tip end side of the first boom swings between the first boom and the second boom in the left and right directions. A vertical connecting pin that is movably connected and a boom cylinder mounting bracket to which the boom cylinder is mounted are provided between the vehicle body and the boom cylinder mounting bracket, and the boom cylinder mounting bracket is longer than the vertical connecting pin in the longitudinal direction of the first boom. It is configured to project to the front side.

With this structure, the boom cylinder mounting bracket provided on the tip end side of the first boom can be made to project to the front side of the vertical connecting pin, and the distance between the projecting end side and the vehicle body side. Can be widened, so that the stroke of the boom cylinder mounted between them can be increased. This makes it possible to set a large depression / elevation angle between when the first boom is moved downward and when the first boom is moved upward without forming the first boom in a long shape.

The invention according to claim 2 further comprises a self-propelled vehicle body and an offset boom-type front attached to the vehicle body. The offset boom-type front is mounted on the vehicle body and is lifted by a boom cylinder. A first boom that is lifted downwards, a second boom that is attached to the tip end side of the first boom and swings left and right by an offset cylinder, and a left and right tip end side of the second boom. A third boom that is swingably attached to the first boom and is held in parallel with the first boom by a link; and an arm that is attached to the tip end side of the third boom and that is rotated upward and downward by an arm cylinder. An offset boom type construction machine comprising a work tool attached to the tip end side of the arm and pivoted upward and downward by a work tool cylinder, wherein the first boom is attached to the tip end side of the first boom. A vertical coupling pin that swingably connects the boom and the second boom to the left and right directions; and a boom cylinder mounting bracket to which the boom cylinder is mounted, provided between the boom and the second boom. The bracket is configured to project forward of the vertical connecting pin in the longitudinal direction of the first boom.

Thus, the stroke of the boom cylinder mounted between the protruding end side of the boom cylinder mounting bracket and the vehicle body side can be increased, and the elevation angle of the first boom can be increased.

Further, according to the invention of claim 3, the boom cylinder mounting bracket has a pin hole into which the tip side of the boom cylinder is pin-connected, and the pin hole is longer than the vertical connecting pin in the longitudinal direction of the first boom. It is configured to be arranged on the front side in the direction.

As a result, the pin hole of the boom cylinder mounting bracket can be arranged at the front side away from the vehicle body.
A boom cylinder with a large stroke can be attached between the pin hole and the vehicle body side.

According to the fourth aspect of the present invention, the boom cylinder mounting bracket is provided with a reinforcing member for increasing the joint strength of the mounting bracket to the first boom.

As a result, the boom cylinder mounting bracket can be firmly joined to the first boom by using the reinforcing member, so that the durability thereof can be improved.

Further, according to the invention of claim 5, the boom cylinder mounting bracket has a pin hole into which the tip side of the boom cylinder is pin-connected, and the pin hole is a vertical connecting pin with respect to the longitudinal direction of the first boom. It is configured to be arranged at almost corresponding positions.

Thus, the pin hole of the mounting bracket can be arranged at a position substantially corresponding to the vertical connecting pin, and the strength of the entire mounting bracket can be increased.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An offset boom type construction machine according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

1 to 8 show a first embodiment according to the present invention. In the present embodiment, a small turning type hydraulic excavator will be described as an example.

In the figure, 1 is a lower traveling body of the hydraulic excavator, 2
Is an upper revolving structure rotatably mounted on the lower traveling structure 1. The upper revolving structure 2 has, for example, a support structure having a bottom plate 3A and left and right vertical plates 3B, 3B (only one is shown). And a cab 4 provided on the left side of the front part of the upper revolving structure 2 in which a driver's seat (not shown) is arranged, and on the revolving frame 3 located behind the cab 4. A building cover 5 that covers various devices such as an installed engine and a hydraulic pump (not shown), and a counterweight 6 that is provided on the rear end side of the revolving frame 3 and that balances weight between a front 9 described later. It is configured to include.

Here, as shown in FIG. 5, on each vertical plate 3B of the revolving frame 3, there is a boom mounting hole 7 in which a first boom 10 to be described later is rotatably (moved up and down), and a boom cylinder to be described later. A tube mounting hole 8 into which a tube 15A of 15 is rotatably mounted is provided.

The upper swing body 2 is, as shown in FIG.
The revolving frame 3, the cab 4, the building cover 5, the counterweight 6 and the like are formed in a substantially circular shape so that the revolving frame 3, the cab 4, the building weight 5, the counterweight 6 and the like are located within a fixed revolving radius R about the revolving center O (axis OO). In the hydraulic excavator according to the present embodiment, the outer diameter of the upper swing body 2 is 1.2 relative to the vehicle width of the lower traveling body 1.
The hydraulic excavator is formed so as to have a size within twice the size, and is configured as a small turning hydraulic excavator.

Reference numeral 9 denotes an offset boom type front member which is located on the right side of the cab 4 and is capable of raising and lowering the upper revolving superstructure 2. The front end 9 has a base end side as shown in FIGS. A first boom 10 which is attached to a boom attachment hole 7 of the revolving frame 3 so as to be able to move up and down by using a first boom connecting pin 29 described later, and the first boom 10
The second boom connecting pin 32, which will be described later, on the tip side of the
A second boom 11 that is swingably mounted in the right direction, a third boom 12 that is swingably mounted in the left and right directions on the tip end side of the second boom 11, and an upper portion of the third boom 12 that is mounted on the third boom 12. An arm 13 rotatably mounted in the downward direction and a bucket 14 as a working tool mounted rotatably in the upper and lower directions on the tip end side of the arm 13.

Here, the first boom 10 is the upper plate 2 described later.
2, a bottom plate 23, left and right side plates 24, and the like, which is formed as an elongated hollow structure having a bent distal end side, which is located at the proximal end side thereof and extends linearly, and a boom base portion 10A, and the distal end of the boom base portion 10A. It has a tip portion 10B that is provided on the side by being bent in a substantially "V" shape.

A boom cylinder 15 for raising and lowering the first boom 10 is mounted between the first boom 10 and the swing frame 3, and the boom cylinder 15 has a base end as shown in FIGS. The tube 15A is rotatably pin-coupled to the tube mounting hole 8 of the swivel frame 3 by using the tube-side connecting pin 16, and the tube 15A is extendably inserted into the tube 15A. A rod 15 rotatably pin-connected to a rod mounting hole 34 of a boom cylinder mounting bracket 33, which will be described later.
And B.

An offset cylinder 18 for swinging the second boom 11 in the left and right directions is provided between the first boom 10 and the second boom 11, and the first boom 10 and the third boom 12 are connected to each other. In between, the first to third booms 10,
A link 19 forming a parallel link with 11 and 12 is provided. Further, an arm cylinder 20 for rotating the arm 13 upward and downward is provided between the third boom 12 and the arm 13, and a bucket 14 is moved upward and downward between the arm 13 and the bucket 14. A bucket cylinder 21 is provided as a working tool cylinder that is rotated in the direction.

When the offset cylinder 18 is expanded / contracted, the second boom 1 is moved toward the tip of the first boom 10.
1 swings left and right. At this time, the third boom 12
Are oscillated in the opposite direction to the second boom 11 by the link 19 and are held in parallel with the first boom 10. As a result, the front 9 is moved (offset) in parallel to the left side or the right side from the neutral position shown by the solid line in FIG.
5, the arm cylinder 20, the bucket cylinder 21 and the like are expanded and contracted, and the first boom 10, the arm 13, the bucket 14 and the like are operated to perform excavation work on the gutters and the like.

Next, referring to FIGS. 4 to 6, the first
The structure of the boom 10 will be described.
Is formed by welding a plurality of steel plates, and the upper plate 2
2, a lower plate 23, left and right side plates 24, 24, a boss portion 28 described later, and second boom mounting brackets 30, 30.

Here, the lower plate 23 is formed such that the portion constituting the lower surface side of the tip portion 10B of the first boom 10 is flat.
This portion is a flat surface portion 23A. Further, the left side plate 24 is provided with three bracket plates 25, 26, 27 projecting outward at the tip end side thereof, and the link 19 swings between the upper and middle bracket plates 25, 26. It is movably connected and has intermediate and lower bracket plates 26, 2
An offset cylinder 18 is swingably connected between the seven.

Reference numeral 28 denotes a boss portion constituting the base end side of the first boom 10, and the boss portion 28 uses a first boom connecting pin 29 to boom the vertical plate 3B of the revolving frame 3 as shown in FIG. It is rotatably connected to the mounting hole 7.

Reference numeral 30 denotes a pair of second boom mounting brackets constituting the tip end side of the first boom 10. Each of the second boom mounting brackets 30 is formed of, for example, a metal plate or the like, and has left and right side plates 24. They are joined together and are arranged at intervals in the upper and lower directions in FIG. The mounting brackets 30 are formed with pin insertion holes 31 that are open on the upper side and the lower side of the first boom 10 and are coaxial with each other.

Reference numeral 32 is a second boom connecting pin as a vertical connecting pin provided between the first boom 10 and the second boom 11, and the second boom connecting pin 32 has an axis A- as shown in FIG. A, each mounting bracket 3 on both sides in the length direction
While being inserted into the pin insertion hole 31 of No. 0, an intermediate portion in the length direction is inserted into a boss portion or the like provided on the base end side of the second boom 11. As a result, the second boom connecting pin 32 connects the first boom 10 and the second boom 11 with the axis A-.
It is connected so as to be swingable in the left and right directions about A.

Reference numeral 33 denotes a pair of boom cylinder mounting brackets provided on the lower surface of the tip of the first boom 10. The boom cylinder mounting brackets 33 are formed of, for example, elongated metal plates as shown in FIG. ing. In addition, each mounting bracket 33 extends in the longitudinal direction of the tip end portion 10B of the first boom 10, and the second boom connecting pin 32 is provided.
It is placed on both the left and right sides with the pinch in between.

The mounting bracket 33 has one end side (base end side) in the length direction of the lower plate 2 by means such as welding.
3 is joined to the flat surface portion 23A, an intermediate portion in the length direction is joined to the second boom mounting bracket 30 on the lower side, and is erected substantially perpendicularly to these.

On the other end side (tip side) of each mounting bracket 33, there is formed a protruding end portion 33A protruding forward from the second boom mounting bracket 30 in the longitudinal direction of the first boom 10. There is. As a result, the boom cylinder mounting bracket 33 protrudes farther to the front side in the longitudinal direction of the first boom 10 than the axis AA of the second boom connecting pin 32.

Reference numeral 34 is a rod mounting hole as a pin hole formed in each protruding end portion 33A of each boom cylinder mounting bracket 33. The rod mounting holes 34 are arranged coaxially with each other with a space in the left and right directions. The rod-side connecting pin 17 is inserted into the inside thereof. Then, the rod 15 of the boom cylinder 15 is inserted into the rod mounting hole 34.
B is rotatably attached by a rod-side connecting pin 17.

Here, as shown in FIG. 2, the center of the rod mounting hole 34 (rod-side connecting pin 17) is, for example, the second boom connecting pin 32 in the longitudinal direction of the tip portion 10B of the first boom 10. It is arranged at a position on the front side of the axis A-A by a dimension B (a position close to the third boom 12), and this position is ahead of the second boom mounting bracket 30.

As a result, in this embodiment, as shown in FIG. 5, the distance L between the rod mounting hole 34 on the first boom 10 side and the tube mounting hole 8 on the revolving frame 3 side can be increased. In between, a boom cylinder 15 having a long stroke in which a tube 15A is formed long can be attached.

On the other hand, in the prior art, for example, as shown by a phantom line in FIG. 5, the rod mounting hole 101 of the boom cylinder mounting bracket 100 has the second boom connecting pin 32.
Since it is arranged on the rear side (vehicle body side) of the axis line AA, the distance between the rod mounting hole 101 and the tube mounting hole 8 becomes smaller than that of the present embodiment, and the boom cylinder 102 has a smaller distance. The length is limited to a small size.

Reference numeral 35 denotes a reinforcing plate as a reinforcing member provided between the left and right boom cylinder mounting brackets 33.
As shown in FIGS. 4 to 6, the reinforcing plate 35 is made of, for example, a metal plate or the like, and the thickness dimension thereof is the flat surface portion 2 of the lower plate 23.
It is formed thinner than the 3A or boom cylinder mounting bracket 33.

The reinforcing plate 35 is arranged at a position rearward of the axis AA of the second boom connecting pin 32 (position close to the vehicle body). The reinforcing plate 35 has a flat surface portion 23A of the lower plate 23 on the upper end side by means such as welding.
Both ends in the left and right directions are respectively joined to the boom cylinder mounting brackets 33, whereby the joint strength of each mounting bracket 33 to the lower plate 23 (first boom 10) is increased.

The hydraulic excavator according to the present embodiment has the above-mentioned structure, and its operation will be described below.

First, when excavating a gutter or the like with a hydraulic excavator, for example, the offset cylinder 18 is operated to move the second boom 11, the third boom 12, the arm 13, the bucket 14, etc. of the front 9 to the left side of the vehicle body. Or offset to the right. Then, by expanding and contracting the boom cylinder 15, the arm cylinder 20, the bucket cylinder 21, etc. at this position, the first boom 10,
The second boom 11, the bucket 14 and the like can be operated to excavate earth and sand and the like.

Further, when excavating a deep groove or the like, as shown in FIG. 7, for example, the boom cylinder 15 and the arm cylinder 2 are used.
By reducing 0, the bucket cylinder 21 and the like to almost the minimum position, the front 9 can be largely moved downward, and in this state, the bucket 14 can be dug deep into the ground. .

Further, for example, when performing a swinging motion in a small swinging posture during excavation work, as shown in FIG. 8, the boom cylinder 15, the arm cylinder 20, the bucket cylinder 21 and the like are extended to almost the maximum position so that the arm 13 is extended. ,
While rotating the bucket 14 and the like so as to be folded toward the vehicle body side, the first to third booms 10, 11, and 12 are largely swung upward. As a result, the front 9 is erected upward and has a small turning posture within the turning radius R of the upper turning body 2, so that the turning operation can be smoothly performed even in a narrow work site, for example.

Thus, in the present embodiment, since the rod mounting hole 34 of the boom cylinder mounting bracket 33 is arranged in front of the second boom connecting pin 32 by the dimension B, this rod mounting hole 34 Swivel frame 3
The distance L to the tube mounting hole 8 on the side can be set to a larger dimension as compared with the prior art, and a boom cylinder 15 having a large stroke can be mounted between these mounting holes 8 and 34.

Thus, for example, when excavating a deep trench,
A sufficient excavation depth can be ensured by reducing the boom cylinder 15, and the front cylinder 9 can be easily made into a small turning posture by greatly extending the boom cylinder 15 during a turning operation. On the other hand, a sufficient elevation angle can be given.

Therefore, according to the present embodiment, it is possible to give a sufficient stroke to the boom cylinder 15 only by changing the shape of the boom cylinder mounting bracket 33, etc., and the front end including the first boom 10 etc. It is possible to improve the performance such as the depth of excavation at a low cost while reducing the size and weight of the whole 9.

In this case, since the rod mounting hole 34 is arranged on the front side of the tip end side of the first boom 10 (the second boom mounting bracket 30), the rod mounting hole 34 may be formed depending on the size and shape of the first boom 10, for example. The arrangement of 34 and the distance L are not restricted, and the degree of freedom in designing these parts and the boom cylinder 15 can be increased.

Further, since the reinforcing plate 35 is provided between the left and right boom cylinder mounting brackets 33 at a portion closer to the vehicle body than the second boom connecting pin 32, the first boom 10
The joint strength of each mounting bracket 33 to the reinforcing plate 35
Can be surely increased. This allows the mounting brackets 3 to be moved along with the expansion and contraction of the boom cylinder 15.
When an external force is applied to the protruding end portion 33A side of the mounting bracket 33, the reinforcing plate 35 arranged on the base end side of each mounting bracket 33
Can be reinforced at a well-balanced position. Moreover, since the mounting bracket 33 and the reinforcing plate 35 are welded to the flat surface portion 23A of the lower plate 23, these members can be easily joined to the first boom 10 with high strength.

On the other hand, when the boom cylinder mounting bracket 33 according to the present embodiment is configured to use, for example, the boom cylinder 102 similar to that of the prior art, the first boom 10 is shortened by a dimension B, for example. By forming the rod mounting hole 34 in the boom cylinder 10
It can be arranged at a position corresponding to 2. Therefore, in this case, the length and the like of the first boom 10 can be reduced, and the front 9 can be made lighter and more compact.

When the total length of the first boom 10 and the second boom 11 is fixed, for example, the second boom 1 is formed by the short length of the first boom 10.
Since 1 can be formed in a long length, it becomes possible to offset the tip side of the second boom 11 formed in a long length in the left and right directions with a large movement amount while maintaining the same excavation depth as in the prior art. It is possible to improve excavation performance such as gutter digging.

Next, FIGS. 9 to 10 show a second embodiment according to the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals, The description will be omitted.

However, in the present embodiment, the boom cylinder mounting bracket 41 is formed to be shorter than that in the first embodiment, and the rod mounting hole 42 provided at the tip side thereof is provided.
Is formed at a position substantially equal to the axis AA of the second boom connecting pin 32 with respect to the longitudinal direction of the tip portion 10B of the first boom 10, for example.

Here, when the rod mounting hole 42 is arranged at a position substantially equal to the axis A--A, sufficient strength is secured on the tip side of the first boom 10 including the boom cylinder mounting bracket 41. Therefore, it is not necessary to provide a reinforcing member between the mounting brackets 41.

Thus, in this embodiment having such a structure, it is possible to obtain substantially the same operational effects as those of the first embodiment. In particular, in the present embodiment, each rod mounting hole 42 is connected to the axis line A-A of the second boom connecting pin 32.
Since it is arranged at a position almost equal to, the durability of the boom cylinder mounting bracket 41 and the like can be further enhanced,
For example, the reinforcing plate 35 and the like used in the first embodiment can be omitted.

Next, FIG. 11 shows a third embodiment according to the present invention, which is characterized in that an arm stay is used instead of the third boom at the front. In addition, in the present embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

Reference numeral 51 is a front face provided on the swing frame 3 of the upper swing body 2 so as to be able to move up and down.
Almost the same as the first embodiment, the first boom 10, the second boom
It has a boom 11, an arm 13, a bucket 14, a boom cylinder 15, an offset cylinder 18, a link 19, an arm cylinder 20, a bucket cylinder 21 and the like.
However, the front 51 is configured to include an arm stay 52 described later, instead of the third boom 12 of the first embodiment.

A boom cylinder mounting bracket 33 is provided on the tip end side of the first boom 10, and the rod mounting hole 34 is longer than the axis AA of the second boom connecting pin 32 in the longitudinal direction of the first boom 10. It is located on the front side in the direction.

Reference numeral 52 denotes an arm stay which forms an intermediate portion of the front 51, and the arm stay 52 is the second boom 1
It is attached to the tip side of 1 so as to be swingable in the left and right directions. Further, the arm 13 is provided on the tip side of the arm stay 52.
Is rotatably attached in an upward and downward direction, and the arm cylinder 20 is provided between the arm stay 52 and the arm 13.
Is provided. A link 19 is attached between the arm stay 52 and the first boom 10.

When the front 51 is operating, the second
When the boom 11 is swung to the left and right by the offset cylinder 18, the arm stay 52 is held in parallel with the first boom 10 by the link 19, and in this state, the arm stay 52, the bucket 14, and the like are left or right. Offset to. Therefore, the front 51 is capable of excavating the gutter or the like by operating the first boom 10, the arm 13, the bucket 14, etc. at these offset positions.

Thus, in this embodiment having such a structure, it is possible to obtain substantially the same operational effects as those of the first embodiment. That is, since the stroke of the boom cylinder 15 can be increased to give a sufficient depression / elevation angle to the first boom 10 without forming the first boom 10 in a long shape, the entire front 9 can be made smaller and lighter. It is possible to improve performance such as excavation depth.

In each of the above-described embodiments, the bucket 14 is described as an example of the work tool, but the present invention is not limited to this, and various work tools including, for example, a grapple, a crusher, a vibrator, and the like. May be attached to the front 9.

Further, in the embodiment, the hydraulic excavator has been described as an example of the offset boom type construction machine.
Of course, the present invention is not limited to this and can be applied to various offset boom type construction machines other than hydraulic excavators.

[0071]

As described in detail above, according to the first aspect of the invention, the boom cylinder mounting bracket is provided to the offset boom type front having the first boom and the second boom rather than the vertical connecting pin. 1 Since it is configured to project to the front side in the longitudinal direction of the boom, a sufficiently large distance can be provided between this mounting bracket and the vehicle body side as compared with the prior art, and the stroke between them can be A large boom cylinder can be attached. Therefore, simply by changing the shape of the boom cylinder mounting bracket,
It is possible to increase the degree of freedom in designing the boom cylinder and the like, to give a sufficient depression / elevation angle to the first boom, and to improve performance such as excavation depth while reducing the size and weight of the entire front. You can

According to the second aspect of the invention, the boom cylinder mounting bracket is projected forward of the first boom in the longitudinal direction of the first boom with respect to the offset boom type front having the first to third booms. With this configuration, the stroke of the boom cylinder can be set large without forming the first boom or the like in a long shape, and the depression / elevation angle of the first boom can be sufficiently increased. Therefore, it is possible to improve the performance such as the excavation depth while reducing the size and weight of the entire front.

Further, according to the invention of claim 3, the pin hole of the boom cylinder mounting bracket is arranged on the front side in the longitudinal direction of the first boom with respect to the vertical connecting pin. It is possible to easily increase the stroke of the boom cylinder mounted between the two.

According to the fourth aspect of the invention, the boom cylinder mounting bracket is provided with the reinforcing member for increasing the joining strength to the first boom. Therefore, the mounting bracket is firmly fixed to the first boom by the reinforcing member. It can be joined to and its durability can be improved.

Further, according to the invention of claim 5, since the pin hole of the boom cylinder mounting bracket is arranged at a position substantially corresponding to the longitudinal connecting pin in the longitudinal direction of the first boom, special reinforcement is provided. Without providing members
Sufficient strength can be secured on the tip side of the first boom including the mounting bracket, and the durability thereof can be improved.

[Brief description of drawings]

FIG. 1 is a front view showing a hydraulic excavator according to an embodiment of the present invention.

FIG. 2 is an enlarged front view showing the front of the hydraulic excavator.

FIG. 3 is a plan view showing a front side in FIG.

FIG. 4 is an enlarged view of a main part in FIG. 2, showing a connecting portion between the first boom and the second boom.

FIG. 5 is a partially enlarged view of the hydraulic excavator showing a state in which a boom cylinder is mounted between the vertical plate of the swing frame and the mounting bracket of the first boom.

FIG. 6 is a partial enlarged perspective view of the tip portion of the first boom seen from the lower left side.

FIG. 7 is a partial front view of the hydraulic excavator showing a state in which the boom cylinder is extended and the front is largely moved downward.

FIG. 8 is a front view of the hydraulic excavator showing a state in which the boom cylinder is contracted and the front is largely lifted upward.

FIG. 9 is a front view showing a hydraulic excavator according to a second embodiment of the present invention.

FIG. 10 is an enlarged view of an essential part of the front of the hydraulic excavator according to the second embodiment of the present invention seen from the same position as in FIG.

FIG. 11 is a front view showing a hydraulic excavator according to a third embodiment of the present invention.

[Explanation of symbols]

1 Undercarriage (car body) 2 Upper revolving structure (car body) 3 swivel frames 4 cabs 5 building cover 6 counter weight 7 Boom mounting hole 8 Tube mounting hole 9,51 front 10 First boom 11 second boom 12 Third boom 13 arms 14 Buckets (work implements) 15 boom cylinder 15A tube 15B rod 16 Tube side connecting pin 17 Rod side connecting pin 18 offset cylinder 19 links 20 arm cylinder 21 Bucket cylinder (work implement cylinder) 22 Upper plate 23 Lower plate 23A Flat surface part 24 side plate 25,26,27 bracket plate 28 Boss 29 First boom connecting pin 30 Second boom mounting bracket 31 pin insertion hole 32 Second boom connecting pin (vertical connecting pin) 33, 41 Boom cylinder mounting bracket 33A protruding end 34, 42 Rod mounting hole (pin hole) 35 Reinforcing plate (reinforcing member) 52 Arm stay

Claims (5)

[Claims] 1. A self-propelled vehicle body and an offset boom type front attached to the vehicle body, wherein the offset boom type front is mounted on the vehicle body and is lifted and lowered in the upward and downward directions by a boom cylinder. An offset boom including a first boom, a second boom mounted on the tip side of the first boom and swung left and right by an offset cylinder, and a work implement mounted on the tip side of the second boom. In the construction machine, a vertical connecting pin, which connects the first boom and the second boom so as to be swingable in the left and right directions, is provided on the tip side of the first boom, and the boom is provided between the vehicle body and the vertical connecting pin. A boom cylinder mounting bracket to which a cylinder is mounted is provided, and the boom cylinder mounting bracket projects to the front side in the longitudinal direction of the first boom with respect to the vertical connecting pin. Offset boom type construction machine, characterized in that it was. 2. A self-propelled vehicle body and an offset boom type front mounted to the vehicle body, wherein the offset boom type front is mounted on the vehicle body and lifted and lowered by a boom cylinder. A first boom, a second boom mounted on the tip side of the first boom and swingable left and right by an offset cylinder, and a swingable left and right direction on the tip side of the second boom. And a third boom that is held in parallel with the first boom by a link, an arm that is attached to the tip end side of the third boom and that is turned upward and downward by an arm cylinder, and a tip end side of the arm. In an offset boom type construction machine including a work tool attached and rotated upward and downward by a work tool cylinder, a first boom and a second boom are provided on a tip side of the first boom. A vertical connecting pin that swingably connects between the left and right sides and a boom cylinder mounting bracket to which the boom cylinder is mounted are provided between the vehicle body and the boom cylinder mounting bracket. Also, the offset boom type construction machine is characterized in that it is configured to project to the front side in the longitudinal direction of the first boom. 3. The boom cylinder mounting bracket has a pin hole into which the tip end side of the boom cylinder is pin-connected, and the pin hole is arranged on the front side in the longitudinal direction of the first boom with respect to the vertical connecting pin. The offset boom type construction machine according to claim 1. 4. The offset boom type construction machine according to claim 1, wherein the boom cylinder mounting bracket is provided with a reinforcing member for increasing the joint strength of the mounting bracket to the first boom. 5. The boom cylinder mounting bracket has a pin hole into which a tip end side of the boom cylinder is pin-connected, and the pin hole is at a position substantially corresponding to the longitudinal connecting pin with respect to the longitudinal direction of the first boom. The offset boom type construction machine according to claim 1 or 2, wherein the offset boom type construction machine is arranged.