JPH1136375A - Traveling vibration-control hydraulic circuit in construction machine with wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a traveling vibration-control hydraulic circuit through which prevents traveling vibration on a rugged road face and prevents a working machine from freely moving up and down while traveling with loads or without loads. SOLUTION: The traveling vibration-control hydraulic circuit of a construction machine with wheels, provided with a hydraulic cylinder 512 freely raising or lowering a working device equipped with a bucket attached to the front part thereof, an accumulator is connected to the rising side B of the hydraulic cylinder 512 through a valve to give the inside pressure of the accumulator to the rising side B of the hydraulic cylinder 512 by opening the valve when the traveling speed V of the machine reaches a specified value V0 and buffer the vertical vibration at the traveling condition by releasing the hydraulic oil of the declining side H of the hydraulic cylinder 512. A plurality of accumulators 65H, 65L are provided and the inside pressure of respective accumulators are set in sequence in the hydraulic pressure of the rising side B of the hydraulic cylinder 512 of the condition from the loaded bucket to the vacant bucket.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling vibration damping hydraulic circuit of a wheeled construction machine, and in particular, loads earth-sand and the like on a hydraulically driven working machine provided at a front part of a vehicle body and travels on uneven road surfaces. The present invention relates to a hydraulic circuit capable of suitably damping vertical vibration generated during traveling in a wheeled construction machine made possible.

[0002]

2. Description of the Related Art FIG. 3 is a side view of a wheeled shovel (hereinafter referred to as "example machine"). The work machine 50 includes a boom 51 having a base end connected to a front portion of the vehicle body 40 by a pin connection 511 and capable of raising and lowering by a boom cylinder 512, and a pin connection 521 to a tip end of the boom 51 and a bucket cylinder 523 via a link 522. And a bucket 52 that can be dumped freely. That is, since the working machine 50 is provided at the front part of the vehicle body 40, is a heavy object, and is a wheeled type, when the working machine runs on an uneven road surface, the working machine is subject to vertical vibration. I do. This vertical vibration increases as the vehicle speed of the example machine increases. Therefore, as a traveling vibration damping hydraulic circuit for absorbing the energy of the vertical vibration to attenuate the vertical vibration, for example, there is a hydraulic circuit shown in FIG.

[0003] This hydraulic circuit comprises an operating valve 61 and an oil tank 6.
2 and a hydraulic pump 63. When the operator operates the operation valve 61, the oil in the oil tank 62 is
And the operation valve 61 in this order to become pressure oil, and the cylinder 5
12, 523 to expand and contract them.

In the hydraulic circuit, an accumulator 65 is connected to the bottom side B of the boom cylinder 512 via a first on-off valve 64. Further, a branch is made from between the first on-off valve 64 and the accumulator 65 and the second on-off valve 66
And an oil passage connected between the operation valve 61 and the hydraulic pump 63 through the oil passage. The head side H of the boom cylinder 512 and the oil tank 62 are connected to an on-off valve 67 (hereinafter referred to as a “fifth on-off valve 67”).
).

[0005] First, second, fifth opening and closing valves 64, 66, 67
Are solenoid valves, and respective drive currents are supplied from a controller 68. Specifically, as shown in FIG. 4, when there is no drive current, the first and second on-off valves 64 and 66 are closed by the biasing forces of the respective springs, and the fifth on-off valve 67 is a built-in check valve. Thus, it is possible to flow only in the direction of the head side H (hereinafter referred to as “one-way open”). The check valve of the fifth on-off valve 67 functions as a so-called vacuum prevention valve for the head side H of the boom cylinder 512.

On the other hand, when there is a driving current, the biasing forces of the respective springs are overcome, and the first and fifth on-off valves 64 are opened, and the second and fifth on-off valves are opened.
The opening / closing valve 66 is provided by a built-in check valve and the accumulator 6.
5 (only one direction). This check valve cooperates with a pressure switch 69 and a controller 68, which will be described in detail later, to control the internal pressure Pa of the accumulator 65.
Act as a so-called pressure reducing valve that keeps the pressure constant.

[0007] As described above, the controller 68 includes the first, second,
It is connected to the fifth on-off valves 64, 66, 67 to supply a drive current to each of them. Further, the controller 68 detects the internal pressure Pa of the accumulator 65 and sends a signal S of “Pa ≧ Po” when the internal pressure Pa is equal to or higher than the set pressure Po, and a vehicle speed for detecting the vehicle speed V of the example machine. Detector 70
And a changeover switch 72 provided on the instrument panel 71 in the driver's seat and switched between ON and OFF by the operator.

That is, the controller 68 includes a first pressure switch 69,
The signals S, V from the vehicle speed detector 70 and the changeover switch 72,
Upon being turned on, a drive current is supplied to each of the first, second, and fifth on-off valves 64, 66, and 67 according to an operation program stored in advance. Table 2 shows the operation program of the controller 68.
This will be described with reference to FIG.

[0009]

[Table 2]

(1) Before the operation of the example machine (V = 0), it is as follows. The changeover switch 72 is turned off. And since it is before the operation, no power is generated. Therefore, the first, second, and fifth on-off valves 64, 66, 67 do not receive the drive current. That is, as described above, the first and second on-off valves 64 and 66 are closed by the urging forces of the respective springs (“×” in Table 2).
), The fifth on-off valve 67 is opened in one direction (indicated by “△” in Table 2). Note that, in order to facilitate the following description, the relationship between the internal pressure Pa of the accumulator 65 and the set pressure Po before this operation is “Pa <Po”.

(2) At the time of starting the example machine, it is as follows. The operator turns on the power by turning on the engine start switch. Note that the changeover switch 72 remains OFF.
At this time, since initially “Pa <Po”, the first pressure switch 69 does not input the signal S to the controller 68. Therefore, the controller 68 sets the second on-off valve 6 under the condition that the signal S is not received.
6 is supplied with a drive current and is opened in one direction. Then, the operator operates the operation valve 61 to raise the boom cylinder 512 for self-propelled operation. By doing so, the pump discharge pressure Pp of the hydraulic pump 63 is reduced by the boom cylinder 51.
The pressure is increased in accordance with the load of No. 2 (the weight of the working machine 50, etc.). The pressure oil based on the pump discharge pressure Pp is supplied to the second on-off valve 6.
After that, it flows into the accumulator 65. When the internal pressure Pa of the accumulator 65 increases to “Pa = Po”, the first pressure switch 69 gives a signal S to the controller 68. The controller 68 eliminates the drive current to the second on-off valve 66 on condition that the signal S is received from the first pressure switch 69 and closes it.

(3) When the example machine is running, the operator switches the changeover switch 72 to ON. Controller 68 receives signal ON from changeover switch 72. On the other hand, the controller 68 stores the vehicle speed V from the vehicle speed detector 70 in advance as a reference vehicle speed Vo.
(For example, Vo = 6 km / h). When the vehicle speed V increases and the controller 68 determines “V ≧ Vo”, the controller 68
Applies a drive current to the first and fifth on-off valves 64 and 67 to open them (marked with “○” in Table 2). As a result, the bottom side B of the boom cylinder 512 communicates with the accumulator 65, and the head side H of the boom cylinder 512 communicates with the oil tank 62. Therefore, even if the example machine travels on an uneven road surface and vibrates up and down, the energy of the up and down vibration of the working machine 50 is absorbed by the accumulator 65 and attenuated, so that the up and down vibration of the example machine is damped. At this time, since the controller 68 receives the signal S from the first pressure switch 69, the controller 68 keeps the second on-off valve 66 closed.

(4) When the example machine arrives at the work site and the cylinders 512 and 523 expand and contract to perform excavation work, the operator sets the changeover switch 72 to OFF.
The controller 68 returns the first, second, and fifth on-off valves 64, 66, and 67 to the stop state (1) under the condition that the signal ON is not received from the changeover switch 72.

(5) When the excavation work is completed and the example machine resumes running, the operator switches the changeover switch 72 to ON. The controller 68 receives the signal ON from the changeover switch 72, and returns the first, second, and fifth opening / closing valves 64, 66, 67 to the running state (3).

[0015]

However, the above prior art has the following problems. In a vehicle such as an example machine, a load traveling in which the bucket 52 runs full of earth and sand, and the like,
There is an empty load traveling in which the soil and the like of the bucket 52 are discharged and the bucket 52 travels. However, since there is only one set pressure Po (that is, the internal pressure Pa of the accumulator 65), when the set pressure Po is set in accordance with the loading state of the bucket 52 and the vehicle runs idle, the work is performed when the vehicle speed V reaches the reference vehicle speed Vo. A phenomenon occurs in which the machine 50 rises on its own. Conversely, when the load is set and the set pressure Po is set to the unloaded state, when the vehicle travels, the work machine 50 sinks when the vehicle speed V reaches the reference speed Vo.
Discomforting the operator. In addition, there is a problem that the cargo is accidentally dropped.

The present invention has been made in view of the above-mentioned problems of the prior art,
To provide a traveling vibration damping hydraulic circuit for a wheeled construction machine in which a working machine does not rise or fall without permission, whether it is loading traveling or empty traveling, in addition to damping traveling vibration on uneven road surfaces. With the goal.

[0017]

Means for Solving the Problems and Functions / Effects In order to achieve the above object, a hydraulic vibration damping hydraulic circuit for a wheeled construction machine according to the present invention is provided at the front of the wheeled construction machine. A hydraulic cylinder that allows the working machine with a bucket provided on the hydraulic cylinder to move up and down, an accumulator is connected to the starting side of the hydraulic cylinder via an open / close valve, and the open / close valve is opened when the vehicle speed exceeds a predetermined vehicle speed. In the traveling vibration damping hydraulic circuit of the wheeled type construction machine, the vertical pressure during traveling is damped by applying the internal pressure of the accumulator to the starting side of the accumulator and releasing the hydraulic oil on the lower side of the hydraulic cylinder, It is characterized in that it has a plurality of accumulators for sequentially setting the internal pressure of each accumulator from the loaded state of the bucket to the hydraulic pressure on the starting side of the hydraulic cylinder in the unloaded state.

According to the first configuration, the following effects can be obtained. The pressure accumulating means sequentially sets the internal pressure of each accumulator from the loaded state of the bucket to the hydraulic pressure on the starting side of the hydraulic cylinder in the empty state. Therefore, when the vehicle speed becomes equal to or higher than the predetermined vehicle speed, the opening / closing valve is opened, and the hydraulic pressure according to the loaded state or the unloaded state can be supplied from the accumulator to the starting side of the hydraulic cylinder. At this time, the pressure oil on the lower side of the hydraulic cylinder is released. For this reason, even when the wheeled construction machine travels on uneven road surfaces, the working machine does not rise or fall without permission, whether in a loaded state or in an unloaded state, and vibration of the traveling vibration can be suppressed.

Second, a hydraulic cylinder is provided which is capable of raising and lowering a work machine with a bucket provided at the front of a wheeled construction machine. An accumulator is connected to the starting side of the hydraulic cylinder via an on-off valve, and the vehicle speed is increased. When the vehicle speed exceeds a predetermined vehicle speed, the opening / closing valve is opened to apply the internal pressure of the accumulator to the starting side of the hydraulic cylinder, and the hydraulic oil on the underside of the hydraulic cylinder is released to buffer vertical vibration during traveling. In the traveling vibration damping hydraulic circuit of the wheel type construction machine, (1) the hydraulic cylinder 51
High-pressure accumulator 65H and low-pressure accumulator 65 connected in parallel via the first on-off valve 64
L, (2) switch 72, (3) high pressure accumulating means 69 for accumulating high pressure in high-pressure accumulator 65H, (4) low pressure accumulating means 76 for accumulating low pressure in low-pressure accumulator 65L, (5) ) First open / close valve 64 and high-pressure accumulator 6
5H, (3) a third on-off valve 73L provided between the first on-off valve 64 and the low-pressure accumulator 65L, (7) a first on-off valve 64 and 4 open / close valve 7
3L, a discriminating means 75 for discriminating whether the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is high pressure or low pressure,
(8) Upon receiving a signal from the switch 72, the first opening / closing valve 64 is opened, and the detection result from the discriminating means 75 is received.
(81) If the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is high, the third opening / closing valve 73H is opened and the fourth opening / closing valve 73 is detected.
L is closed and the hydraulic oil on the lower side H of the hydraulic cylinder 512 is released, while (82) if the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is low, the third on-off valve 73H is closed and the fourth on-off valve 7
And a controller 681 for opening 3L and releasing the pressure oil on the lower side H of the hydraulic cylinder 512.

According to the second configuration, the following effects can be obtained. The controller 681 receives the signal from the switch 72 and
The on-off valve 64 is opened. Then, the discriminating means 75 can discriminate whether the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is high or low. Then, the controller 681 receives the detection result from the discriminating means 75, and if the detection result indicates that the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is high, when the vehicle speed V becomes equal to or higher than the predetermined vehicle speed Vo, The third on-off valve 73H is opened, the fourth on-off valve 73L is closed, and the hydraulic oil on the lower side H of the hydraulic cylinder 512 is released. On the other hand, if the detection result from the discriminating means 75 indicates that the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is low, when the vehicle speed V further becomes equal to or higher than the predetermined vehicle speed Vo, the third on-off valve 73H is closed. Fourth on-off valve 73
L is opened, and the hydraulic oil on the lower side H of the hydraulic cylinder 512 is released. For this reason, even when the wheeled construction machine travels on uneven road surfaces, the working machine does not rise or fall without permission, whether in a loaded state or in an unloaded state, and vibration of the traveling vibration can be suppressed.

[0021]

FIG. 1 shows a first embodiment of the present invention.
FIG. 2 shows a second embodiment. The example machine is the same wheeled shovel as in FIG. 3 described above, and has a hydraulically driven working machine 50 at the front of the vehicle body 40. On the other hand, as shown in FIG. 1 and FIG. 2, the hydraulic circuit is partially the same as FIG. Therefore, in FIGS. 1 and 2, the same elements as those in FIG. 4 are denoted by the same reference numerals, and overlapping detailed description will be omitted. That is, in the first and second embodiments, as shown in FIGS. 1 and 2, the boom cylinder 512, the bucket cylinder 523, the operation valve 61, the oil tank 62, the hydraulic pump 63, the first opening / closing valve 64 , The second on-off valve 66 (in addition,
In the second embodiment, the second on-off valves 66H, 66H for high pressure and low pressure are used.
L) and the oil passage connection with the fifth on-off valve 67 are the same as in FIG. The controller 681 in the first embodiment (the controller 682 in the second embodiment) corresponds to the controller 68 in FIG. The controller 681 (the controller 682 in the second embodiment) and the first
An on-off valve 64, a second on-off valve 66 (second on-off valves 66H, 66L for high pressure and low pressure in the second embodiment), a fifth on-off valve 67, and a first pressure switch 69 (high pressure in the second embodiment). , Low-pressure switches 69H, 69L), the vehicle speed detector 70, and the changeover switch 72 are the same as those in FIG. In such a hydraulic circuit, the first and second embodiments differ from the hydraulic circuit of FIG. 4 as follows. First, a first embodiment will be described with reference to FIG.

In the first embodiment, as shown in FIG.
It has low-pressure accumulators 65H and 65L.

The high-pressure accumulator 65H passes through a third on-off valve 73H and a first on-off valve 64 to the boom cylinder 51.
2 is connected to the bottom side B. In the high-pressure accumulator 65H, the oil path to the third on-off valve 73H branches, and the branched oil path includes a check valve 74 that opens in one direction toward the high-pressure accumulator 65H and a second on-off valve 66 in this order. It is connected between the operation valve 61 and the hydraulic pump 63 through the above. The internal pressure PH of the high-pressure accumulator 65H is set between the high-pressure accumulator 65H and the second on-off valve 66.
When it is 1 or more (PH ≧ P1), the signal S is sent to the controller 68
1 to provide a first pressure switch 69. Set pressure P1
Is a value substantially equal to the pressure on the bottom side B of the boom cylinder 512 that can hold the work implement 50 in the air when the bucket 52 is loaded with earth and sand.

On the other hand, the low-pressure accumulator 65L is
It is connected to the bottom side B of the boom cylinder 512 via the on-off valve 73L and the first on-off valve 64. Note that a second pressure switch 75 that provides a signal P to the controller 681 when the hydraulic pressure during this period is substantially equal to the set pressure P2 is provided between the fourth and first on-off valves 73L and 661. In addition, accumulator 6 for low pressure
5L is an oil passage branched to a fourth on-off valve 73L, and the branched oil passage is connected between a check valve 74 and a second on-off valve 66 via a pressure reducing valve 76 set at a set pressure P2. Have a road. Note that the set pressure P2 of the pressure reducing valve 76 is set to a value substantially equal to the pressure on the bottom side B of the boom cylinder 512 that can hold the work implement 50 in the air when the bucket 52 is in the unloaded state. And, of course, the set pressures P1 and P2 are "P
1> P2 ".

The third and fourth on-off valves 73H and 73L are also electromagnetic valves like the first, second and fifth on-off valves 64, 66 and 67, and their driving currents are supplied from a controller 681. Specifically, as shown in FIG. 1, when there is no driving current, the first to fourth on-off valves 6 are actuated by the urging forces of the respective springs.
4, 66, 73H, 73L are closed, and the fifth on-off valve 66,
67 is opened in one direction by a built-in check valve. on the other hand,
When there is a drive current, the first, third to fifth on-off valves 64, 73H, 73L, 67 open by overcoming the biasing forces of the respective springs, and the second on-off valve 66 opens in one direction.

That is, the controller 681 receives the signals S, P, V, and ON from the first and second pressure switches 69 and 75, the vehicle speed detector 70, and the changeover switch 72, and receives the first to first signals according to the operation program stored in advance. 5 on-off valves 64, 66, 73H,
A drive current is given to each of 73L and 67L. Controller 6
An example of the operation program 81 will be described with reference to Table 1.

[0027]

[Table 1]

(1) Before the operation of the example machine (V = 0), it is as follows. The changeover switch 72 is turned off. And since it is before the operation, no power is generated. Therefore, the first to fifth on-off valves 64, 66, 73H, 73L, 67 do not receive the drive current. That is, the first to fourth on-off valves 64, 66, 73
H and 73L are closed (marked with “x” in Table 2), and the fifth on-off valve 67
Is opened in one direction (marked with “△” in Table 1). In order to facilitate the following description, the internal pressures PH and PL of the high-pressure and low-pressure accumulators 65H and 65L and the set pressure P before this operation.
1, the relationship with P2 is “PH <P1” and “PL <P2”.

(2) When starting the example machine, the following is performed (the bucket 52 is empty). The changeover switch 72 remains OFF. At this time, since initially “PH <P1”, the first pressure switch 69 does not input the signal S to the controller 681. Therefore, the controller 681 applies a drive current to the second on-off valve 66 under the condition that the controller 681 does not receive the signal S, and makes the second on-off valve 66 open in one direction (indicated by “△” in Table 1). When the operator operates the operation valve 61 to raise the boom cylinder 512 for self-propelling, the pump discharge pressure Pp of the hydraulic pump 63 is increased.
Increases in accordance with the load on the boom cylinder 512 (the weight of the work machine 50). Then, pressure oil based on the pump discharge pressure Pp flows into the high-pressure and low-pressure accumulators 65H and 65L via the second on-off valve 66. When the pump discharge pressure Pp increases to the set pressure P2 of the pressure reducing valve 75 (Pp = P2), the internal pressure PL of the low-pressure accumulator 65L is reduced by the pressure reducing valve 75.
Is maintained at “PL = P2”. The pump discharge pressure Pp may be further increased by operating the operation valve 61. However, since the bucket 52 is empty, the pump discharge pressure Pp does not increase much thereafter. That is, the internal pressure PH of the high-pressure accumulator 65H is “P2 <PH <P1”. Accordingly, the first pressure switch 69 does not provide the signal S to the controller 681. For this reason the second
The on-off valve 66 remains open in one direction.

(3) Then, the example machine is driven to the excavation site (empty load traveling). At this time, the operator switches the changeover switch 72 to ON. When the controller 681 receives the signal ON from the changeover switch 72, it supplies a drive current to the first on-off valve 64 to open them (marked by “○” in Table 2). Thus, the oil pressure between the first and fourth on-off valves 64 and 73L becomes the oil pressure P2 on the bottom side B of the boom cylinder 512. Therefore, the second pressure switch 75 inputs the signal P of “PL = P2” to the controller 681. And the controller 681
Is comparing the vehicle speed V from the vehicle speed detector 70 with a predetermined vehicle speed Vo (for example, Vo = 6 km / h) stored in advance. Then, when the vehicle speed V increases and the controller 681 determines “V ≧ Vo”, the controller 681 opens the fourth and fifth on-off valves 73L and 67. As a result, the bottom side B of the boom cylinder 512 communicates with the low-pressure accumulator 65L,
The head side H of the boom cylinder 512 communicates with the oil tank 62. For this reason, even if the example machine runs empty on uneven road surfaces,
The energy of the vertical vibration of the work machine 50 is absorbed and attenuated by the low-pressure accumulator 65L. Therefore, the vertical vibration of the example machine is damped. Boom cylinder 51
Since the unloading hydraulic pressure PL is applied to the bottom side B of the work machine 2, when the vehicle speed V reaches the reference vehicle speed Vo, the working machine 50
Does not float on its own. At this time, the controller 68
1 indicates that the second on-off valve 66 remains open in one direction under the condition that the signal S is not received from the first pressure switch 69.

(4) When the example machine arrives at the work site and the cylinders 512 and 523 expand and contract to perform excavation work, the operator turns off the changeover switch 72. Controller 681
Returns the first to fifth opening / closing valves 64, 66, 73H, 73L, 67 to the state at the time of starting in the above (2) under the condition that the signal ON is not received from the changeover switch 72. By the way, during excavation work, the pump discharge pressure Pp rises and falls greatly depending on the load.
Therefore, the large pump discharge pressure Pp (Pp> P2)
It flows into the high-pressure accumulator 65H via the on-off valve 66 and the check valve 74. And high pressure accumulator 65H
When the internal pressure PH becomes “PH = P1”, the controller 681 receives the signal S from the first pressure switch 69 and
Close 6.

(5) When the excavation operation is completed and the example machine runs with the earth and sand loaded on the bucket 52 (that is, when the load travels),
The operator switches the changeover switch 72 to ON. When the controller 681 receives the signal ON from the changeover switch 72,
A drive current is applied to the first opening / closing valve 64 to open them (marked “○” in Table 2). By doing so, the oil pressure between the first and fourth on-off valves 64 and 73L becomes the oil pressure P1 on the bottom side B of the boom cylinder 512. That is, the second pressure switch 75
Is not “PL = P2”, the signal P is sent to the controller 681.
Do not enter in. Therefore, the fourth on-off valve 73L remains closed. On the other hand, the controller 681 stores the vehicle speed V from the vehicle speed detector 70 in advance at a predetermined vehicle speed Vo (for example, Vo = 6 km /
h). When the vehicle speed V increases, the controller 681 sets “V ≧
Vo ”, the controller 681 determines the third and fifth on-off valves 7
3H and 67 are supplied with a drive current to open them (Table 2).
"○" mark). As a result, the bottom side B of the boom cylinder 512 communicates with the high-pressure accumulator 65H, and the head side H of the boom cylinder 512 and the oil tank 62 are connected.
Communicates with For this reason, even if the example machine is loaded on an uneven road surface, the energy of the vertical vibration of the work machine 50 is absorbed and attenuated by the high-pressure accumulator 65H, so that the vertical vibration of the example machine is damped. Boom cylinder 51
Since the hydraulic pressure PH is applied to the bottom side B of 2, when the vehicle speed V reaches the reference vehicle speed Vo, the working machine 50 does not sink without permission. Also, there is no accidental drop of the cargo. As can be understood from the above description, the second pressure switch 75 is a discriminating means for discriminating whether the example machine is traveling with a load or traveling with an empty load.

Next, a second embodiment will be described with reference to FIG. The difference from the first embodiment of FIG. 1 is as follows. Instead of the second on-off valve 66 in the first embodiment, a high-pressure accumulator 65
The difference is that a high-pressure second on-off valve 66H is provided for H, while a low-pressure second on-off valve 66L is provided for the low-pressure accumulator 65L. Further, the second on-off valve 6 for high pressure
6H to high pressure accumulator 65H
The point is that a pressure switch 69H is provided, and a pressure reducing valve 76 is eliminated between the second low pressure on-off valve 66L and the low pressure accumulator 65L, and a first low pressure pressure switch 69L is provided instead. Although various operation programs of the controller 682 in this hydraulic circuit can be prepared, it is not necessary to explain that they can be set in the same manner as the operation program example described in the first embodiment. That is, the high pressure second on-off valve 66H inputs the signal S to the controller 682 when the high pressure accumulator 65H is "PH = P1". On the other hand, the low-pressure second on-off valve 66L inputs the signal P to the controller 682 when the low-pressure accumulator 65L is "PL = P2". Here, similarly to the first embodiment, the second pressure switch 75 is not limited to the discriminating means for discriminating whether the example machine is traveling with the load or traveling with the empty load.

The high-pressure accumulating means 6 for accumulating a high pressure in the high-pressure accumulator 65H described in the claims.
"9" corresponds to the first pressure switch 69 in the first embodiment, and corresponds to the high pressure first pressure switch 69H in the second embodiment. On the other hand, the "low pressure accumulating means 7 for accumulating a low pressure in the low pressure accumulator 65L" described in the claims.
"6" corresponds to the pressure reducing valve 76 in the first embodiment, and corresponds to the low pressure first pressure switch 69L in the second embodiment.

In the first and second embodiments, for high pressure,
Although the low-pressure accumulators 65H and 65L are provided,
A plurality of accumulators may be provided, and the internal pressure of each accumulator may be sequentially set from the loaded state of the bucket 52 to the hydraulic pressure on the starting side B of the hydraulic cylinder 512 in the empty state.

In FIG. 1 (first embodiment) and FIG. 2 (second embodiment), reference numeral 77 denotes a pressure relief switch. The operation and effect of the depressurizing switch 77 are as follows. When checking and repairing various devices in the hydraulic circuit, it is necessary to lower the hydraulic pressure in the circuit. Therefore, when the operator turns on the depressurizing switch 77 for the first, third, fourth, and fifth on-off valves 64, 73H, 73L, and 67, the controllers 681 and 6 are turned on.
A drive current is supplied instead of the drive current from 82, and these are opened. Next, the operator operates the operation valve 61 as appropriate, so that the high and low pressure accumulators 65H and 65H are operated.
L also ensures that the hydraulic pressure on the head side H of the boom cylinder 512 is released to ensure the safe operation.

[Brief description of the drawings]

FIG. 1 is a traveling vibration suppression hydraulic circuit of a first embodiment.

FIG. 2 is a traveling vibration suppression hydraulic circuit according to a second embodiment.

FIG. 3 is a side view of the wheeled construction machine.

FIG. 4 is a traveling vibration damping hydraulic circuit of a conventional wheeled construction machine.

[Explanation of symbols]

512 ... boom cylinder (hydraulic cylinder), 64 ... first
On-off valve, 65H high-pressure accumulator, 65L low-pressure accumulator, 66 second on-off valve, 66H high-pressure second on-off valve (second on-off valve), 66L low-pressure second on-off valve (second on-off valve) ), 67: fifth on-off valve, 69: first pressure switch (high pressure accumulating means), 69H: high pressure first pressure switch (high pressure accumulating means), 69L: low pressure first pressure switch (low pressure accumulating means) ), 76 ... pressure reducing valve (low pressure accumulating means),
72, a switch, 73H, a third on-off valve, 73L, a fourth on-off valve, 75, a second pressure switch (discriminating means), 681,
682: controller, B: bottom side (raising side), H: head side (downside), PH: internal pressure of high-pressure accumulator, PL ...
Internal pressure of accumulator for low pressure, P1, P2 ... set pressure,
P, ON, S: signal, V: vehicle speed, Vo: predetermined vehicle speed.

Claims (2)

[Claims] 1. A hydraulic cylinder for raising and lowering a work machine with a bucket provided at a front portion of a wheeled construction machine, wherein an accumulator is connected to the starting side of the hydraulic cylinder via an on-off valve, and the vehicle speed is controlled to a predetermined value. A wheel-mounted type that opens and closes the on-off valve when the vehicle speed is exceeded to apply the internal pressure of the accumulator to the starting side of the hydraulic cylinder, and releases the hydraulic oil on the underside of the hydraulic cylinder to buffer vertical vibration during traveling. In the traveling vibration damping hydraulic circuit of the construction machine, there is provided a plurality of accumulators, and a pressure accumulating means for sequentially setting the internal pressure of each accumulator from the loaded state of the bucket to the hydraulic pressure on the starting side of the hydraulic cylinder in the empty state. The traveling vibration damping hydraulic circuit of the wheeled construction machine. 2. A hydraulic cylinder capable of raising and lowering a work machine with a bucket provided at a front part of a wheeled construction machine. An accumulator is connected to the starting side of the hydraulic cylinder via an on-off valve, and the vehicle speed is controlled to a predetermined value. A wheel-mounted type that opens and closes the on-off valve when the vehicle speed is exceeded to apply the internal pressure of the accumulator to the starting side of the hydraulic cylinder, and releases the hydraulic oil on the underside of the hydraulic cylinder to buffer vertical vibration during traveling. In the traveling vibration damping hydraulic circuit of the construction machine, (1) a high-pressure accumulator 65H and a low-pressure accumulator 65L connected in parallel to the starting side B of the hydraulic cylinder 512 via the first on-off valve 64;
(2) switch 72 and (3) high pressure accumulator 65H
Pressure accumulating means 69 for accumulating a high pressure in the accumulator, and (4) a pressure accumulating means 76 for accumulating a low pressure in the low pressure accumulator 65L.
(5) First on-off valve 64 and high-pressure accumulator 65H
(6) the first on-off valve 6
A fourth on-off valve 73L provided between the first and second low-pressure accumulators 65L, and (7) a first on-off valve 64 and a fourth on-off valve 73L.
, A discriminating means 75 for discriminating whether the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is high pressure or low pressure, and (8) receiving the signal from the switch 72 to open the first on-off valve 64 and When the detection result from the means 75 is received and the detection result from the discrimination means 75 when the vehicle speed V becomes equal to or higher than the predetermined vehicle speed Vo is (81) If the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is high, the third opening / closing The valve 73H is opened, the fourth opening / closing valve 73L is closed, and the hydraulic oil on the lower side H of the hydraulic cylinder 512 is released. On the other hand, if the hydraulic pressure on the starting side B of the hydraulic cylinder 512 is low, the third opening / closing is performed. The valve 73H is closed and the fourth on-off valve 73L is closed.
And a controller 681 for opening the hydraulic oil on the lower side H of the hydraulic cylinder 512.