JPH10168928A - Impulse absorbing device for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arrange a large-scale accumulator effectively absorbing a large impulse applied at the time of boom lowering operation rationally in a space, in which a piping for a boom cylinder is drawn around. SOLUTION: In a boom mounting section coupled with the frame 2a of a boom, a box structure section consisting of a pair of mounting plates 12, 12 disposed in upright to the frame 2a and a connecting plate 14 stretched between the mounting plates 12, 12 and having high strength is constituted. An accumulator 24 displaying the absorption action of pulsation working to the bottom chamber side in a boom cylinder is installed into the box structure section of the boom mounting section, and the accumulator 24 is detachably set up fixedly onto the frame 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorbing device for a construction machine for absorbing a shock during a boom damping operation of the construction machine.

[0002]

2. Description of the Related Art As is well known, a hydraulic excavator as a construction machine has a lower traveling body and an upper revolving body which is rotatably mounted on the lower traveling body.
As the arm and the front attachment, for example, a front working mechanism including a bucket or the like is provided,
A driver's cab where an operator boards is installed. Also,
Engines, hydraulic pumps and other equipment are also mounted on the revolving superstructure. The boom, arm, and bucket are driven by hydraulic cylinders. Of these, the boom requires the largest driving force. Therefore, in the case of a two-pump system using two hydraulic pumps as a hydraulic circuit, And the hydraulic cylinders from the two pumps
The book is provided.

A typical operation performed using the front attachment is an excavation operation for earth and sand. However, besides excavation, there is, for example, water averaging work. This water averaging operation is an operation of smoothing unevenness by operating the bucket to sweep uneven ground. To perform this water averaging operation, first place the bucket on the near side of the vehicle, lower it to the position where it touches the ground, and operate the boom cylinder and arm cylinder in this state so that they interlock with each other. The bucket is moved in the horizontal direction by changing the angle of the bucket continuously. When the bucket advances to the most forward position, the bucket is moved away from the ground by performing a boom raising operation, and the bucket is again displaced toward the front of the vehicle.
At this time, the bucket must be lowered to a position where the bucket comes into contact with the ground because the bucket is located at a position above the ground. For this purpose, the boom lowering operation is performed by the boom cylinder, but the movement of the boom must be stopped at the position where the bucket comes into contact with the ground or in the vicinity thereof.

[0004] Since the load of the entire front working mechanism acts on the boom, the boom is in a direction against the load during the raising operation of the boom. Therefore, even if the boom is stopped halfway, no particular vibration or the like occurs, but in the direction in which the load acts. If the vehicle is stopped in the middle of a certain boom lowering operation, a large inertia force acts on the boom, and the whole vehicle may vibrate or bounce. This vibration naturally extends to the driver's cab, which not only deteriorates the ride comfort and operability of the operator during this type of work, but also makes it impossible to perform water leveling work unless the vibration is stopped, thus improving work efficiency. Gets worse. Of course, if the boom lowering operation is performed gently, the vibration can be suppressed. However, the operation of the boom becomes slow as described above, and the working efficiency also becomes extremely poor.

[0005] In consideration of the above points, a device having a shock absorbing device for absorbing a shock when the boom is lowered is conventionally known. For example, an accumulator is arranged on the back side at the base end side of the boom, and this accumulator is connected to the bottom side of the boom cylinder, that is, to a pipe connected to the tank side when the boom is lowered, and this accumulator is used during the boom lowering operation. There is a configuration in which an impact is alleviated by setting an operating state.

[0006]

However, from the viewpoint of the above-mentioned work efficiency, it is preferable that the operation for grounding the bucket is performed as fast as possible. Then, the inertia force when stopping from the boom lowering operation becomes extremely large, and a strong impact is applied. In order to effectively absorb such a severe impact, it is necessary to use a large accumulator having a large capacity as much as possible. However, hydraulic piping for the arm cylinder and the bucket cylinder is routed on the back of the boom. Further, in addition to the bucket, a front attachment such as a breaker may be attached to the arm. Since the breaker includes a cylinder for driving the breaker, piping for that is also routed. Therefore, a large number of pipes pass through the back of the boom, and the space for installing the accumulator is restricted, so that there is a problem that a very large accumulator cannot be installed. Also,
Since the accumulator needs to be connected to the bottom side of the boom cylinder, if the accumulator is provided on the back side of the boom, the bottom side piping must be routed once to the back side of the boom, and the piping There is also a problem that it becomes longer than necessary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to allow a large accumulator capable of effectively absorbing a large shock applied during a boom lowering operation to be rationally arranged. It is in.

[0008]

In order to achieve the above-mentioned object, according to the present invention, an accumulator is connected to a pipe connected to a tank when a boom is lowered by a boom cylinder of a construction machine, and the accumulator is connected to an upper rotating body. It is characterized in that it is configured to be provided in a box structure part constituting a boom mounting part. It is most preferable that the accumulator is fixed to the inside of the box structure portion, for example, a floor surface, from the viewpoint of the stability of the accumulator and the connection of piping.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a hydraulic excavator as an example of a construction machine. In the figure, 1 indicates a lower traveling structure, 2 indicates an upper revolving structure, and
Is rotatably installed on the lower traveling body 1.

The upper revolving unit 2 is provided with an operator's cab 3 on which an operator rides, and a front working mechanism 4 is mounted at a position adjacent to the operator's cab 3. The front working mechanism 4 includes a boom 5 connected to the frame 2 a of the upper revolving unit 2 so as to be capable of raising and lowering, an arm 6 rotatably connected to a tip of the boom 5, and a front attachment connected to a tip of the arm 6. The front attachment includes a bucket 7 for performing operations such as excavation of earth and sand. The bucket 7 is rotatably connected to the tip of the arm 6. A boom cylinder 8 and an arm 6 are provided between the boom 5 and the frame 2a of the upper swing body 2 in order to perform a raising operation of the boom 5 with respect to the upper swing body 2.
The arm cylinder 9 is provided between the arm 6 and the boom 5 in order to rotate the bucket 7 with respect to the boom 5, and the bucket 7 and the arm 6 are further rotated in order to rotate the bucket 7 at the tip of the arm 6. Bucket cylinders 10 are connected to each other.

[0011] The boom 5 is connected to the frame 2a,
For this purpose, the frame 2a is provided with a boom mounting portion 11, as shown in FIGS. The boom mounting portion 11 is composed of a pair of mounting plates 1 erected on the frame 2a.
The mounting plate 12 is provided with a pin mounting portion 13, and the base end of the boom 5 is connected to the mounting plate 12 via connecting pins so as to be rotatable in the vertical direction. You.
Since the entire load of the front working mechanism 4 acts on these mounting plates 12, a connecting plate 14 is provided between the two mounting plates 12 and 12 so as to be provided.
And the connection plate 14 and the frame 2a constitute a box structure.

A boom cylinder 8 is mounted on the boom mounting portion 11. Here, two boom cylinders 8 are provided on the left and right, so that the driving force to the boom 5 that supports the entire load acting on the front working mechanism 4 is increased. In order to connect the two boom cylinders 8, a distal end side of the mounting plate 12 is a support bracket portion 12a. In addition, the connecting plate 14 includes
A bracket 15 is provided in parallel with the support bracket portion 12a. A connecting pin is inserted between the support bracket portion 12a and the bracket 15, and the connecting pin supports the boom cylinder 8 so as to be rotatable in the vertical direction. I am trying to do it.

As described above, the two boom cylinders 8 are provided with the support bracket 12a and the bracket 15a.
The connecting portion is on the cylinder side, and the rod side is rotatably connected near the tip of the boom 5. In order to supply pressurized oil to the boom cylinder 8, it is necessary to connect hydraulic piping to the bottom side and the rod side. Since two boom cylinders 8 are provided, the total number of hydraulic piping is four. These hydraulic pipes are two pipes before entering the box structure part, and the bottom side pipe and the rod side pipe are branched into two parts each inside the boom mounting part 11 to form four pipes and connected. It is pulled out through an opening 14 a provided in the plate 14 and connected to each boom cylinder 8.

As described above, the boom 5 is connected to the boom mounting portion 1.
1, the lifting operation is performed by supplying pressure oil to the boom cylinder 8. Therefore, a hydraulic circuit for driving the boom cylinder 8 is shown in FIG. As described above, the boom cylinder 8 has a pair of left and right
That is, two boom cylinders are provided, and in FIG. 4, these boom cylinders are distinguished by using reference numerals 8a and 8b, respectively.

In the illustrated hydraulic circuit, two hydraulic pumps 20a, 20b are provided, and the hydraulic oil discharged from each of the hydraulic pumps 20a, 20b is supplied to the boom cylinder 8a via the direction switching valves 21a, 21b. , 8b. That is, the directional control valves 21a,
In the neutral position, the bottom chamber B and the rod chamber R of the boom cylinders 8a, 8b are shut off when in the neutral position.
20b, the rod chamber R is connected to the tank 22, and the boom cylinders 8a, 8b are displaced in the extending direction. When the boom cylinders 8a, 8b are switched to the other switching position, the rod chamber R is connected to the hydraulic pumps 20a, 20b. The bottom chamber B is connected to the tank 22, and the boom cylinders 8a and 8b are displaced in a contracting direction.

Here, the pressure oil from the hydraulic pumps 20a, 20b is not individually supplied to the boom cylinders 8a, 8b, but joins downstream of the direction switching valves 21a, 21b. An accumulator 24 is provided to be connected to the junction pipe 23. The accumulator 24 is provided with a flexible bladder called a bladder in a casing, and a gas is sealed in the bladder at a predetermined pressure. Therefore, when pulsation occurs in the merging pipe 23, the bladder is compressed, and the pulsation is absorbed. Here, the accumulator 24 is provided by a hydraulic excavator, for example, in a water averaging operation, when a lowering operation of the boom 5 is performed, a side on which a load acts, that is, a bottom chamber B side connected to the tank 22. By absorbing the pulsation acting on the vehicle, the vehicle is prevented from vibrating or bouncing. For this purpose, the accumulator 24 includes the directional control valves 21a, 2
It is connected to the merging pipe 23 between the bottom chamber 1b and the bottom chamber B of the boom cylinders 8a, 8b. Here, the accumulator 24 is necessary when performing water averaging work or the like,
It is sometimes preferable not to operate the accumulator 24 when performing a work such as a normal excavation of earth and sand. For this purpose, an electromagnetic on-off valve 25 is provided between the merging pipe 23 and the accumulator 24, and the electromagnetic on-off valve 25 opens and closes a flow path from the merging pipe 23 to the accumulator 24. In order to drive the boom, it is not always necessary to provide a pair of the hydraulic pump, the direction switching valve, and the boom cylinder.

Although the function of suppressing vibration by pulsation absorption is exhibited by the accumulator 24, the capacity of the accumulator 24 must be as large as possible in order to sufficiently exert this function. Therefore, a large accumulator must be used. Must. Use of the large accumulator 24 requires a large installation space.
Therefore, in the present invention, the large accumulator 24
The boom mounting portion 11 is used to install the boom.

As described above, the boom mounting portion 11
Are the frame 2a of the upper swing body 2 and the left and right mounting plates 12
And a box structure surrounded by the connecting plate 14, and the inside is a space. And in this space,
Only four pipes connected to the boom cylinder 8 pass therethrough, and the other portions are extra spaces. Therefore, it is possible to use the internal space of the box structure as the installation space for the accumulator 24. As a result, the space can be effectively used, and the large accumulator 24 can be installed. Further, since the pipe from the boom cylinder 8 is inserted into this box structure, providing the accumulator 24 connected to this pipe in the same box structure is advantageous from the viewpoint of pipe routing, and Since it can be provided at a position immediately adjacent to the boom cylinder 8, it is more preferable from the viewpoint of suppressing vibration.

An example of the mounting structure of the accumulator 24 in the box structure is shown in FIGS.
The accumulator 24 is attached to the frame 2a having the highest strength in the box structure. In addition, the electromagnetic on-off valve 25 is attached to the inner side of the connecting plate 14. The electromagnetic on-off valve 25 is connected to a pipe 26 from the merging pipe 23, and a pipe 27 from the electromagnetic on-off valve 25 is connected to the accumulator 24. With this arrangement, the space inside the box structure can be effectively used, and the large accumulator 24 can be arranged without difficulty.

In order to fix the accumulator 24, a support plate 28 is provided on the frame 2a, and a connecting plate 29 is fixedly provided on the support plate 28. Support plate 2
Reference numeral 8 denotes a bent metal plate having a vertical portion connected to both sides of a horizontal portion, and an end of the vertical portion is fixed to the frame 2a by welding or the like. The support plate 28
Is shorter than the total length of the accumulator 24, the total length of the connecting plate 29 is also longer than the total length of the support plate 28, and the side surface thereof is fixed to the support plate 28 by means such as welding. . The connecting plate 29 has a pair of upper and lower mounting holes 29a at front and rear positions. The accumulator 24 is fixed and fixed to the connecting plate 29 by a pair of bands 30 provided so as to surround the accumulator 24 on the supporting plate 28. The band 30 has a small-diameter threaded portion 30a at each end thereof. The both ends of the band 30 are inserted into the mounting holes 29a of the connecting plate 29 so as to surround the accumulator 24, and the nut 31 is screwed into the threaded portion 30a. Then, the accumulator 24 is fixed so as to be tightened. Thus, the accumulator 24 is detachably attached, and can be easily replaced when the bladder or the like is damaged. In addition, the support plate 2
Since the metal plate 8 is formed by bending a metal plate, the accumulator 24 is supported in a vibration-proof manner by, for example, mounting an elastic member such as rubber below the horizontal portion of the support plate 28. Transmission of vibration from the frame 2a to the accumulator 24 can be prevented as much as possible.

[0021]

As described above, according to the present invention, the accumulator is provided in the box structure constituting the boom mounting portion of the upper revolving unit, so that the large accumulator capable of effectively absorbing a large shock applied during the boom lowering operation is provided. The accumulator described above can be rationally arranged in the space where the piping of the boom cylinder is routed.

[Brief description of the drawings]

FIG. 1 is an external view of a hydraulic shovel as an example of a construction machine having a boom.

FIG. 2 is an external view showing a mounting portion of a boom in an upper swing body.

FIG. 3 is a plan view of FIG. 2;

FIG. 4 is a hydraulic circuit diagram for driving a boom.

FIG. 5 is a sectional view taken along line XX of FIG. 3 showing the fixing structure of the accumulator;
It is sectional drawing.

FIG. 6 is a view showing the mounting structure of the accumulator as viewed from the direction of the arrow in FIG. 5;

[Explanation of symbols]

 2 Upper revolving structure 2a Frame 5 Boom 8, 8a, 8b Boom cylinder 11 Boom mounting part 12 Mounting plate 14 Connecting plate 15 Bracket 20a, 20b Hydraulic pump 24 Accumulator 25 Electromagnetic on / off valve 28 Support plate 29 Connecting plate 30 Band

Claims (2)

[Claims] An accumulator is connected to a pipe connected to a tank when the boom is lowered by a boom cylinder of a construction machine, and the accumulator is provided in a box structure portion forming a boom mounting portion of the upper swing body. And shock absorber for construction machinery. 2. The shock absorbing device for a construction machine according to claim 1, wherein said accumulator is fixed in said box structure.