JP2003013908A - Hydraulic circuit for working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic circuit for a working machine having a sufficient working speed and speed controllability in no need of tuning for a long period. SOLUTION: The hydraulic circuit for a working machine which controls an implement comprises a telescopic arm equipped with an implement, a hydraulic cylinder installed in the telescopic arm which controls the expansion and contraction of the arm, a control valve which switches over the expansion and contraction of the hydraulic cylinder by feeding oil to the cylinder and oil reservoir close to the hydraulic cylinder. The oil reservoir is connected with the bottom chamber of the hydraulic cylinder through a pilot check valve to close or open a flow of oil from the bottom chamber to the oil reservoir in response to the pressure of oil supplied from the control valve to a head chamber and when the cylinder is in a contraction stage, oil is fed from the control valve to the head chamber of the hydraulic cylinder, while enabling the flow of oil from the bottom chamber to the oil reservoir due to the hydraulic pressure of the head chamber that is higher than the prescribed valve of the hydraulic pressure supplied to the pilot check valve, thereby discharges oil from the bottom chamber to the oil reservoir; and the other hand, when the cylinder is in a expansion stage, the oil in the head chamber is drained out through the control valve, while returning the oil stored in the oil reservoir to the bottom chamber through the pilot check valve.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a working machine.
About the road. [0002] Conventionally, for example, a working machine for excavating a deep foundation
Is a multi-stage telescopic arm as described in Japanese Patent No.
Many have a system. Configuration of such a working machine
Referring to FIG. 9, the work machine 1 includes a lower traveling body.
An upper swing body 9 is provided on the upper swing body 8 so as to be freely swingable.
A boom 2 which can swing up and down on the rotating body 9;
A multi-stage telescopic arm that can also swing and expand and contract vertically
Arm 90. For example, in the case of a three-stage telescopic arm
The multi-stage telescopic arm 90 includes the base arm 3 and the second stage arm.
And a third stage arm 5. Also, 3
At the tip of the step arm 5, for example, a hydraulic working machine
Excavation bucket such as clam bucket 7 is attached
The clam bucket 7 has a hydraulic series (not shown).
Open / close drive. [0003] During excavation work, the work machine 1 is mounted on the ground surface G. L
Boom 2 and multi-stage telescopic arm 90 are excavated
Swung by posture. And the base arm 3, the second arm
The fourth and third stage arms 5 are extended, respectively, to
When the bucket 7 reaches the excavation depth, clam bake
When the cutter 7 is operated, soil and the like are collected in the clam bucket 7.
Be included. After this, the arms 4 and 5 are contracted to
Ket 7 is ground surface G. Lifted to near L
Boom 2 is swung to the position of boom 2a,
The step arm 3 is raised to the position of the base arm 3a.
You. Next, the upper swing body 9 of the work machine 1 is moved to a predetermined position.
The base arm 3 is turned and the base arm 3b is turned.
To the position of
The earth and sand in the pit 7 are loaded. The drilling location is the desired drilling depth
The above operation is repeated until the time comes. FIG. 10 shows a base stage arm 3 and a second stage arm 4.
Of the multi-stage telescopic arm 90 having the second and third-stage arms 5
The configuration is shown. The lower part of the base arm 3 of the three-stage telescopic arm
The tip of the boom 2 that can swing up and down, such as the work machine 1
Swingably mounted through the boom mounting part 3g.
You. Hydraulic series to control expansion and contraction of the second and third stage arms 4 and 5
The third arm 5 of the final stage and the second arm 5
It is built in the step arm 4. Hydraulic cylinder 10
The head attachment end 10a is attached to the upper end of the second stage arm 4,
The tube mounting end 10b of the hydraulic cylinder 10 is the third stage
It is attached to the upper end of the system 5. [0005] Further, a pair of fixed sheaves 5 for lifting.
0, 50 are provided at the lower end of the second stage arm 4,
The fixed sheaves 50, 50 are located at the third stage when viewed from the boom 2.
The arm 5 is disposed on both left and right sides so as to sandwich the arm 5. one end
Are connected to the connection ends 51a, 51 at the outer lower end of the base arm 3, respectively.
1a, a pair of second stage arms 4
The ear ropes 51, 51 are connected through the respective fixed sheaves 50, 50.
Through the inside of the second arm 4 to the third arm 5
The other end of the wire rope 51, 51 is a third-stage arm
5 at a pair of connection ends 51b, 51b at the outer upper end.
Connected. [0006] A pair of fixed sheaves 52 for pushing down
It is provided at the upper end of the second stage arm 4, respectively.
Fixed sheaves 52, 52 are arranged on the left and right when viewed from the boom 2.
Have been. One end of the lower end of the base arm 3
A pair of two stages connected at a pair of connection ends 53a, 53a
Each of the wire ropes 53 for pushing down the eye arm 4
Of the second arm 4 via the fixed sheaves 52
To the third arm 5 through the wire rope 53,
The other end of the pair 53 is a pair of the outer upper end of the third-stage arm 5.
Are connected at connection ends 53b, 53b. Each of the above-mentioned arms having the above configuration
The operation of 3, 4, and 5 will be described. Hydraulic cylinder 10 extends
Then, this driving force causes the third-stage arm 5 to move to the second-stage arm 5.
It descends so as to protrude from the lower part of the arm 4. this
The connection ends 53b, 53b at the upper end of the third stage arm 5
A pair of wire ropes 53, 53 connected to
The fixed sheaves 52, 52 are pushed downward respectively.
The second arm 4 is located below the base arm 3 because it can be lowered.
It descends so that it protrudes from. Also, hydraulic cylinder
When 10 is shortened, the third-stage arm 5 rises and the second-stage arm 5 rises.
The arm 5 is drawn into the
A pair of wires connected to the connection ends 51b at the upper end of the
The ropes 51, 51 are pulled upward. At this time
The constant sheaves 50, 50 are each lifted upward.
The lower part of the second arm 4 is close to the lower end of the base arm 3.
As a result, the second stage arm 4 becomes the base stage arm.
It is drawn inside 3 and rises. FIG. 11 shows the oil driving the hydraulic cylinder 10.
3 shows a pressure circuit. Variable displacement hydraulic pump (hereinafter referred to as hydraulic pump
19) is driven by a motor (not shown).
You. The discharge line 20 of the hydraulic pump 19 is a hydraulic cylinder.
It is connected to an operation valve 11 for controlling the expansion and contraction of 10. This
The operating valve 11 is operated by an operating lever 23 operated by an operator.
, So that it can be switched. [0009] Downstream pipe line 22a and bottom of operation valve 11
The bottom chamber 10 of the hydraulic cylinder 10 through the side pipe 22b
connected to y. The downstream pipe 22a branches.
The drain line 29 is connected to the drain line 29.
9, a pilot check valve 18 is interposed. This pa
Ilot check valve 18 is connected via drain lines 30 and 31
And connected to the tank 6. Thus, the downstream pipe 2
2a and the drain line 2 in parallel with the bottom side line 22b.
9, 30, 31 are provided. The pilot check valve 18 is an operation valve 1
Pilot line 46 branching from downstream line 21a
Is connected to Pyro from this pilot line 46
The pilot check valve 18 opens by receiving the cut pressure.
You. A downstream pipe 21a of the operation valve 11 and a counter
It is connected to the balance valve 16. This counter balance
The valve 16 is connected to the hydraulic cylinder 10 via the head-side conduit 21b.
Of the head chamber 10x. This head side pipeline 2
1b is connected to a branch conduit 24 that branches. This branch
Connect the line 24 to the relief valve 14 and
Valve 14 is connected to pilot check valve 15 via line 25.
Connected. This pilot check valve 15 is connected to line 2
6 and the bottom side pipeline 22b of the hydraulic cylinder 5
Connected. The pilot check valve 15 is connected to the head.
Connected to the pilot pipeline 45 branching from the pipeline 21b
are doing. The pilot check valve 13 is a hydraulic cylinder 1
0 from the downstream side pipe line 22a connected to the bottom chamber 10y.
It is connected to a diverging pilot pipeline 43. pilot
The check valve 13 is at a pressure supplied from a hydraulic pump 19.
Open operation. The pilot check valve 13 is
To the pilot check valve 15 via a gas line 44.
Connected. Further, the pilot check valve 13 is
It is connected to the variable throttle 17 via a cut line 45. Yes
The variable throttle 17 is connected to the head-side conduit 21 of the hydraulic cylinder 10.
b. This pilot check valve 13 is oil
When the opening operation is performed with the pressure supplied from the pressure pump 19, the pie
The pilot pressure in the lot lines 44 and 45 is
From the check valve 13 via the line 47 to the drain line 30,
Drain from 31 to tank 6. The pilot line 45 is a hydraulic cylinder.
Branch from the head side pipe line 21b connected to the head side 10
are doing. Through this pilot line 45, clamba
Holding pressure generated in the head chamber 10x due to the weight of the ket 7, etc.
Presses the pilot check valves 13 and 15. The counterbalance valve 16 is a check valve 1
6a and a pressure regulating valve 16b. Pressure regulating valve 16
The set pressure of b indicates that the clam bucket 7 rapidly drops the underground hole.
The operating valve 11 is suddenly set to the neutral position and closed
Release the high pressure in the head side pipe line 21b instantaneously
It has a set pressure of the order. Also, the setting of the pressure regulating valve 16b
The pressure is controlled by a relief valve interposed on the branch line 24.
14 is set higher than the set pressure. Oil
The pressure oil discharged from the head side of the pressure cylinder 10 is a pressure regulating valve.
16b so that it cannot flow through the branch pipe 24
I have. A variable throttle 17 is provided on the pilot line 45.
Is interposed. This variable aperture 17 is a pilot chain.
This is for adjusting the responsiveness of the check valve 15. downstream
In the pipeline from the side pipeline 22a to the bottom pipeline 22b,
A relief valve 12 for adjusting the hydraulic pressure of the downstream pipe 22a is provided.
Has been placed. The set pressure of the relief valve 12 is
The maximum pressing force when pressing the ram bucket 7 to the bottom of the hole
This is the oil pressure to be set. In FIG. 11, the hydraulic equipment in the range R1 is shown.
Is mounted near and adjacent to the hydraulic cylinder 10.
You. Further, the downstream pipelines 21a and 22a in the range R2 and the
The three hoses of the lane line 31 connect the clam bucket 7
Two hoses (shown) that feed oil to the actuator that opens and closes
Z) from the hose reel (not shown) onto the boom 2
Along the revolving superstructure 9 for example 20 meters
Have a length. The hydraulic circuit equipment in the range R3 is
It is mounted on the rotating body 9. Next, the operation of the hydraulic circuit shown in FIG. 11 will be described.
I do. When the operating lever 23 is operated upward, the operating valve 1
1 switches to position c. This allows the hydraulic pump 19
The pressure oil to be discharged passes through the operation valve 11 to the downstream pipe 21a.
Check valve 16a of the counterbalance valve 16, head
The head chamber 1 of the hydraulic cylinder 10 is connected via the side conduit 21b.
Flow into 0x. At this time, the pressure oil is
Check from pilot line 46 branching off
Acts on the valve 18 to perform an opening operation. This allows drain pipe
The path 29 and the drain pipe 30 are in communication. In the head chamber 10x of the hydraulic cylinder 10,
The inflowing hydraulic oil shortens the hydraulic cylinder 10,
The arm 4 and the third-stage arm 5 at the tip are shortened simultaneously. oil
Drain discharged from the bottom chamber 10y of the pressure cylinder 10
Oil is supplied to the bottom pipe 22b, the downstream pipe 22a,
Drain from valve 11 to tank 6. In parallel with this
Pressure oil flowing into the head chamber 10x of the hydraulic cylinder 10
Is a pilot pipe 46 branched from the downstream pipe 21a.
Acts on the pilot check valve 18 via the
U. Thereby, from the bottom chamber 10y of the hydraulic cylinder 10
The drain oil discharged is drain line 29, pilot
Through the check valve 18 and the drain lines 30 and 31
Sometimes drain to tank 6. Next, the operating lever 23 is operated to descend.
Then, the operation valve 11 is switched to the position b. This allows the hydraulic
The pressure oil discharged from the pump 19 passes through the operation valve 11 and is located on the downstream side.
The hydraulic cylinder is connected from the pipe 22a through the bottom pipe 22b.
It flows into the bottom chamber 10y of the die 10. At this time the hydraulic pon
The pressure oil discharged from the pump 19 is pyrolyzed from the downstream pipe 22a.
Acts on pilot check valve 13 via cut line 43
Then, it opens. As a result, the pilot lines 44, 45
Pressure oil remaining in the pilot check valve 13 and pipe line 4
7. Drain to tank 6 via drain lines 30, 31
Is performed. On the other hand, the head chamber 10x of the hydraulic cylinder 10
Drain oil from the tank passes through the head side pipeline 21b and is counted.
Attempts to flow into the pressure balance valve 16
Set pressure relief between branch line 24 and line 25
The pressure regulating valve 16b is open because it is higher than the set pressure of the valve 14.
do not do. For this reason, the drain oil is discharged from the head side pipeline 21b.
Flow into the branch line 24, the pressure rises and is higher than the bottom side
A predetermined pressure acts on the relief valve 14 and the relief valve 14
14 is opened and the pilot check valve 15 is
Through the pipe 26. From this relief valve 14
The discharged pressure oil is supplied to the hydraulic pump 19 through the bottom side pipeline 22b.
Into the bottom side of the hydraulic cylinder 10
To increase the extension speed. The hydraulic cylinder 1
The hydraulic oil flowing into the bottom chamber 10y of the hydraulic cylinder 10
And the second stage arm 4 and the third stage arm 5 at the end are the same.
Extends with time. The prior art described above
Has the following problems. First, the hood by oil flow rate
The problem of the pressure loss in the pump will be described. Hydraulic cylinder 10
Oil is fed from the operation valve 11 to the head chamber 10x, and the
Figure 7 is a simplified representation of the hydraulic circuit when raising
12 (a) is obtained. That is, the hydraulic pump 19
The oil is supplied to the head chamber 10x via the operation valve 11 and the pipeline 21a.
Flows into. Also, part of the oil in the bottom chamber 10y is
2a, drain to the tank 6 via the operating valve 11, and
Is drained directly to the tank 6 via the line 31. This
As a result, the tube mounting end 10b of the hydraulic cylinder 10 is
As it rises close to the rod attachment end 10a,
Third stage arm 5 to which the mounting end 10b is attached
As it rises, the clam bucket 7 also rises. At this time,
Oil in the bottom chamber 10y having a larger volume than the head chamber 10x
Represents not only a pipe 22a passing through the operation valve 11, but also a tank
Drains quickly through line 31 which communicates directly with 6
Trying to get a big ascent rate. But
In the same way as the drain pipes 22a and 31,
Since the pipe 21a is also long, the pipes on both the drain side and the supply side are used.
The pressure loss is large in the passages 22a, 31 and 21a,
The problem of not being able to get enough climbing speed because it can be suppressed
There is. On the other hand, the bottom chamber 10y of the hydraulic cylinder 10
Oil from the operating valve 11 to lower the clam bucket 7
FIG. 12 (b) shows a simplified hydraulic circuit when
Swell. That is, the oil from the hydraulic pump 19 is supplied to the operating valve 1
1. Flow into the bottom chamber 10y via the pipe 22a. Ma
The oil in the head chamber 10x is supplied to the head side pipeline 21b,
Flows into the bottom chamber 10y through the passage 24 and the conduits 25 and 26
I do. Thereby, the tube mounting end of the hydraulic cylinder 10
10b descends away from rod attachment end 10a
Therefore, the clam bucket 7 also descends. Thus, the head
By the side pipe 21b, the branch pipe 24, and the pipes 25 and 26.
The oil in the head chamber 10x is bottled through the configured regeneration circuit.
By supplying the oil to the chamber 10y, the oil in the head chamber 10x is supplied.
Do not return to tank 6. This allows the head
Pressure loss in the hose from the chamber 10x to the tank 6
And quickly supply oil to the bottom chamber 10y.
Trying to get a good descent speed. However, line 2
2a is long and the pressure loss is large,
Sufficient descent speed cannot be obtained because the flow velocity is suppressed
Problem. Next, the clam bucket 7 by the operation valve 11
The problem of speed controllability will be described. Clam bucket 7 is empty
When the multi-stage telescopic arm 90 is in a substantially vertical state
The hydraulic cylinder 10 depends on the weight of the clam bucket 7 and the like.
The force that is trying to extend is working. In this state
When lowering the hydraulic bucket 7
On the flow side, the bottom chamber 10y is controlled only by the throttle 36 of the operation valve 11.
To control the rate of descent. like this
The flow rate is controlled only by the throttle on the upstream side of the hydraulic cylinder 10
Then, the load applied to the hydraulic cylinder 10, for example,
Weight of excavated material taken into the ket 7, each arm 4,5
Is easily affected by the frictional resistance of the clam bucket 7
There is a problem that the speed controllability of the vehicle is not good. Next, tuning of the multi-stage telescopic arm 90
Explain the problem. When the crumb bucket 7 descends,
The oil in the head chamber 10x is relieved by the oil pressure in the head chamber 10x.
When the pressure exceeds the set pressure of the valve 14, the relief valve 14
Flow into the bottom chamber 10y via the lot check valve 15
You. The set pressure of the relief valve 14 is
Although the oil pressure is set to a level that lowers the
Each time a new model is developed, select a spring force to set the set pressure.
Need to be specified. In addition, clam bake full of excavation
When the unit 7 is lifted and held in the middle position,
Check the pilot check valve 15 so that the
The oil passage reaching the pipe 26 from the pipe 25 inside the head chamber 10
It is shut off by the hydraulic pressure of x. Hydraulic pressure of head room 10x
The hole diameter acting on the pilot check valve 15 is also different
It must be selected each time a model is developed. in this way,
When tuning each time a different model is developed,
It is also necessary to consider changes in temperature, etc.
There is such a problem. The present invention has been made to solve the above problems.
It has sufficient work machine speed and excellent speed controllability,
Hydraulic rotation of work equipment that does not require long tuning
It is intended to provide a road. Means for Solving the Problems, Functions and Effects
In order to achieve the target, the first invention is an operation for controlling a work machine.
In the hydraulic circuit of industrial machinery,
Multi-stage telescopic arm and inside the multi-stage telescopic arm
Hydraulic cylinder for controlling the extension and retraction of multi-stage telescopic arm
To switch the expansion and contraction of the hydraulic cylinder
Operating valve and an oil sump located near the hydraulic cylinder.
The oil sump and the bottom chamber of the hydraulic cylinder are
From the bottom chamber to the oil reservoir according to the oil pressure supplied to the head chamber
Through a pilot check valve that blocks and circulates oil flow
When the cylinder is retracted, connect the operating valve to the hydraulic cylinder when the cylinder is retracted.
To the pilot chamber and supply to the pilot check valve
The pressure in the head chamber is larger than the predetermined value.
From the bottom chamber to the sump
When the cylinder is extended, the oil in the head chamber is
And drain the oil collected in the oil sump
It is configured to return to the bottom chamber via a check valve. According to the first invention, the head of the hydraulic cylinder is provided.
When the hydraulic cylinder is shortened by supplying pressurized oil to the
The oil in the Tom chamber flows through the pilot check valve to the bottom chamber.
Is discharged to an oil reservoir located near the Oil sump and bottom chamber
The distance between them is short and the piping resistance is small, so drain from the bottom chamber.
Most of the oil released is drained into the sump and goes through a long pipeline
The oil returning to the tank is almost zero. Also, pressurize the bottom chamber.
When supplying oil to extend the hydraulic cylinder,
The oil that has accumulated in the bot
Come back to the room. Low piping resistance between oil sump and bottom chamber
Most oil flowing into the bottom chamber returns from the sump
And the oil supplied through the long pipeline is almost zero.
Then, a bottle that requires approximately twice the flow rate in and out of the head chamber
A large amount of oil in the system chamber goes directly into and out of the sump,
The pressure loss due to the flow velocity is
Pressure loss
be able to. This will increase the oil flow rate
The expansion and contraction speed of the hydraulic cylinder can be increased.
Good work machine speed can be obtained. Also, for example, in the bottom chamber
When the hydraulic cylinder that supplies oil is extended, the load on
If the chamber works in the direction of vacuum,
Oil is supplied to the bottom chamber at a flow rate that is
Degree can be secured. At this time, return to the tank from the head chamber
For example, the flow rate of discharged oil
Control, meter-out control and speed control
A hydraulic circuit of a working machine with excellent performance can be obtained. In addition, hydraulic
Oil discharged from the head chamber to the bottom chamber when the cylinder is extended
Since it does not have a playback circuit for sending
No need to tune the valve, check valve, etc.
An easy working machine hydraulic circuit is obtained. Embodiments of the present invention will be described below with reference to the drawings.
A description will be given with reference to a plane. FIG. 1 shows a hydraulic circuit according to the present invention.
1 shows a first embodiment of a road. It is driven by the hydraulic circuit of FIG.
The configuration of the hydraulic cylinder 10 and the multi-stage telescopic arm 90 is
Since the configuration is the same as that described in FIG.
Omitted. Hydraulic pump driven by a prime mover (not shown)
The discharge line 20 of the pump 19 is connected to the operation valve 11. This
Operating valve 11 has positions a, b, and c and
Switching by the operating lever 23 operated by the
ing. The downstream pipe 21a of the operation valve 11 is
Ports A3 and A4 on the upstream and downstream sides of the lance valve 68 and the head side
The head chamber 10 of the hydraulic cylinder 10 is connected via the pipe 21b.
x. The downstream pipe 22a of the operation valve 11 is
Upstream and downstream of a parallel circuit having a check valve 61 and a throttle 72
Oil through the ports A1 and A2 and the bottom side pipeline 22b.
It is connected to the head chamber 10y of the pressure cylinder 10. The counter balance valve 68 includes a pressure regulating valve 68b.
And a pilot check valve 68a.
The set pressure of the pressure regulating valve 68b is such that the clam bucket 7
When the valve is rapidly falling, the operating valve 11 is suddenly moved to the neutral position.
When closed, the high pressure in the head side pipeline 21b is instantaneously
It has a set pressure enough to escape. Pilot check
The hydraulic pressure P1 of the port A1 is supplied to the
Supplied, and when the hydraulic pressure P1 is higher than a predetermined value, the pilot
The check valve 68a opens, and the port A4 is connected to the port A3.
Enables the flow toward A third-stage arm adjacent to the hydraulic cylinder 10
The oil sump 69 serving as the oil sump arranged in 5
An oil chamber 69 is provided by a piston 70 slidably inserted.
a and the air chamber 69b. Of the piston 70
A seal (not shown) is attached to the sliding part,
To prevent dust from entering the oil. In the air chamber 69b
Has a vent hole 71 open to the atmosphere. Oil sump 69
The oil chamber 69a includes a pipe 65, a pilot check valve 62,
It is connected to the bottom chamber 10y via a pipe 64. What
The volume of the oil chamber 69a is equal to the piston of the hydraulic cylinder 10.
Bottom chamber 10 when rod is fully extended
It is a volume not less than the volume of y. Pilot check valve 62
Is supplied with the hydraulic pressure P3 of the port A3 through the conduit 63,
When the hydraulic pressure P3 is higher than a predetermined value, the pilot check valve 6
2 performs the opening operation, and controls the flow from the pipe 64 to the pipe 65.
Make it possible. In addition, the hydraulic pressure of the downstream side pipeline 22a is adjusted.
The relief valve 60 is disposed, and the relief valve 60 is set.
When the clam bucket 7 is pressed to the bottom of the hole during excavation,
This is the oil pressure that sets the maximum pressing force at the time. In FIG. 1, the hydraulic equipment in the range S1 is shown.
Is mounted near and adjacent to the hydraulic cylinder 10.
You. Also, two downstream pipes 21a and 22a in the range S2
Is an actuator that opens and closes the clam bucket 7.
With two hoses (not shown)
(Not shown) along the boom 2
The rotator 9 has a length of, for example, 20 meters. Example
The hydraulic device in enclosure S3 is mounted on the upper-part turning body 9. The operation of the hydraulic circuit having the above configuration will be described.
I do. When the operating lever 23 is operated upward, the operating valve 1
1 switches to position c. This allows the hydraulic pump 19
The pressure oil to be discharged passes through the operation valve 11 to the downstream pipe 21a.
From the pilot check valve 68a and the head-side conduit 21b.
Through the head chamber 10 x of the hydraulic cylinder 10
At this time, since the hydraulic pressure P3 becomes a predetermined value or more, the pilot
The check valve 62 opens and is discharged from the bottom chamber 10y.
Most of the oil which flows through line 64 and line 65
Flows into the oil chamber 69a. Discharged from the bottom chamber 10y
A part of the oil that flows into the bottom pipe 22b, the check valve 61,
From the operation valve 11 to the tank 6 through the downstream pipe 22a.
Lane. Thus, it flows into the head chamber 10x
Oil is shortening the hydraulic cylinder 10 so the clam bucket
7 rises. Next, the operating lever 23 is operated to descend.
Then, the operation valve 11 is switched to the position b. This allows the hydraulic
The pressure oil discharged from the pump 19 passes through the operation valve 11 and is located on the downstream side.
The oil passes through the pipe 22a, the throttle 72, and the bottom pipe 22b.
It flows into the bottom chamber 10y of the pressure cylinder 10. This and
When the oil flow path area is reduced by the throttle 72, the hydraulic pressure P1 is reduced.
Pilot check valve 68a opens because it exceeds the fixed value
The oil discharged from the head chamber 10x is port A
4, drained from operation valve 11 to tank 6 through A3
You. Clam bucket 7 in the air and multi-stage telescopic arm 9
Extends the hydraulic cylinder 10 as if 0 were in a nearly vertical state
When the force to be applied works, the bottom chamber 10y is set to a negative pressure.
The pilot checks the oil stored in oil chamber 69a
It flows into the bottom chamber 10y through the valve 62. in this way
Of the bottom side pipe 22b and the pipe 64 in the bottom chamber 10y.
Since the oil flowing from both sides extends the hydraulic cylinder 10,
The clam bucket 7 descends rapidly. Also, clam bake
When the unit 7 lands, or when the multi-stage telescopic arm 90 is horizontal.
When the state is close to the state, the bottom chamber 10y does not become a negative pressure.
Therefore, there is no inflow from the oil chamber 69a, and the hydraulic cylinder 10
Slowly with only the inflow oil from the bottom side pipeline 22b
Elongate. The operation and effect of this embodiment will be described. K
FIG. 2 shows a simplified hydraulic circuit when the ram bucket 7 is raised.
(A). When the clam bucket 7 is raised, the operating valve
11 from the head chamber through the long downstream pipe 21a
10x, and large amount of oil discharged from the bottom chamber 10y.
The part is an oil sump disposed adjacent to the hydraulic cylinder 10.
69 flows into the oil chamber 69a via the short pipes 64 and 65.
You. Part of the oil discharged from the bottom chamber 10y is located on the downstream side.
Drain to the tank 6 via the pipe 22a and the operation valve 11.
However, since the flow rate is small, the downstream pipeline 22a is not shown.
Absent. And the pipelines 64 and 65 connected to the oil chamber 69a are
The pressure drop due to the oil flow rate in the pipeline
Can be regarded as only the downstream side pipeline 21a. The pressure loss is
Since it is proportional to the square, the pressure when the clam bucket 7 rises
The loss ΔPu1 is obtained when the flow velocity to the head chamber 10x is V.
It can be expressed by equation (1). ΔPu1 = k × V ＾ 2 (1) where, k: a constant number ＾: represents a power. Simplified oil when the clam bucket 7 descends
The voltage circuit is shown in FIG. When the crumb bucket 7 descends
The oil from the operation valve 11 passes through the long downstream pipe 22a.
Flows into the bottom chamber 10y and also from the oil chamber 69a.
It flows into the bottom chamber 10y. Oil chamber 69a and bottom chamber 10
Since the pipes 64 and 65 connecting y are short, the bottom chamber 1
Most of the oil flowing into Oy is supplied from oil chamber 69a.
You. Oil flowing into the bottom chamber 10y from the downstream pipe 22a
Therefore, the downstream pipe 22a is not shown. F
The oil in the storage chamber 10x is stored in the tank via the downstream pipe 21a.
Drained to 6. Here, the pressure loss according to the present embodiment is shown in FIG.
In comparison with the pressure loss of the prior art hydraulic circuit described in FIG.
Try. Prior art clam bake described in FIG.
When the cut 7 rises, the oil from the operation valve 11 flows downstream.
It flows into the head chamber 10x through the side conduit 21a. Ma
Further, the oil in the bottom chamber is supplied to the drain pipe 31 and the downstream pipe 22.
a to drain to tank 6 through two
Approximately the same oil flows through the pipe 31 and the downstream pipe 22a.
Assuming that the flow velocity to the head chamber 10x is V, the bottom chamber 10y
The oil volume discharged from the head is the oil volume flowing into the head chamber 10x.
Because the product is approximately twice the product, the drain conduit 31 and the downstream conduit
The flow velocity of each of the 22a becomes V, and the clam bucket 7
The pressure loss ΔPuc when the pressure rises can be expressed by equation (2).
You. As described above, the clamba according to the present embodiment
When the ket 7 rises, the pressure loss is lower than in the prior art.
One third is enough. That is, the pressure loss is lower than that of the conventional technology.
The flow rate of oil in the pipeline can be increased because
A sufficient speed of the ram bucket 7 can be obtained. Also,
When the clam bucket 7 descends, the clam bucket 7 is empty.
When the multi-stage telescopic arm 90 is in a substantially vertical state,
Clam bucket by sucking oil from oil chamber 69a
7 falls rapidly. Also, as shown in FIG.
Flow is restricted by the throttle 37 of the operation valve 11 on the downstream side of the hydraulic cylinder 10.
Meter-out control to control the volume.
Weight of the excavated material taken into
Less likely to be affected by frictional force etc.
Speed controllability is obtained. Further, in the present embodiment,
Relief valve 14 constituting a regeneration circuit as in the prior art;
Since there is no pilot check valve 15, the relief valve 14
Spring and pilot check valve 15 hole diameter
Eliminates the need for FIG. 3 shows a second embodiment of the hydraulic circuit according to the present invention.
An embodiment will be described. Hydraulic syringe driven by the hydraulic circuit of FIG.
The configuration of the damper 10 and the multi-stage telescopic arm 90 will be described with reference to FIG.
Since the configuration is the same as that described above, the description is omitted here.
In the hydraulic circuit of the present embodiment, the first embodiment described with reference to FIG.
A3 of the hydraulic circuit and the downstream of the outlet of the control valve 11
Pipeline 21aa downstream from port B of side pipe 21a
It is arranged so as to be along the pipeline 21a. Other circuits
The description is omitted here because it is similar to FIG. In addition,
In FIG. 3, the hydraulic equipment in the range T1 is a hydraulic cylinder 10
It is mounted near and adjacent to. Also, below the range T2
The three hoses of the flow-side pipelines 21a and 22a and the pipeline 21aa
Is sent to the actuator that opens and closes the clam bucket 7.
Hose reel with two oiling hoses (not shown)
(Not shown) along the boom 2 and the upper rotating body 9
For example, it has a length of 20 meters. Range T3
Are mounted on the upper swing body 9. This implementation
Simplified hydraulic pressure at the time of raising the clam bucket 7 according to the form
The circuit is shown in FIG. Flow flowing into the head chamber 10x
When the speed is V, the downstream pipe 21a and the pipe 21aa
Are respectively one half of V. Pressure at this time
The loss ΔPu2 can be expressed by equation (3). FIG. 4 shows a simplified hydraulic circuit when the clam bucket 7 is lowered.
It is shown in (b). The flow velocity discharged from the head chamber 10x is V
Then, the flow velocity in the downstream pipe 21a and the pipe 21aa
Is the same as when rising, so each is half of V
Ah. As described above, the clamba according to the present embodiment
When the ket 7 rises, the pressure loss is lower than in the prior art.
Only one sixth is needed. That is, the pressure loss is lower than that of the conventional technology.
The flow rate of oil in the pipeline can be increased because
A sufficient speed of the ram bucket 7 can be obtained. Also,
As in the first embodiment, the hydraulic cylinder 10
Meter for controlling the flow rate with the throttle 37 of the downstream operation valve 11
Out control, so it was taken into the clam bucket 7
The influence of the weight of the excavated material, the frictional resistance of each arm 4 and 5, etc.
Excellent speed controllability of the clam bucket 7
It is. Furthermore, the resources constituting the reproducing circuit as in the prior art are used.
Since there is no leaf valve 14 and pilot check valve 15,
Spring of relief valve 14, 15 holes of pilot check valve
No diameter tuning is required. In the present invention, the oil sump 69
The chamber 69a, the air chamber 69b, and the air chamber 69b communicate with the atmosphere.
Vent 71, oil chamber 69a and air chamber 69b
And a piston 70 that isolates
However, as shown in FIG. 5, the first and second air chambers 69b are sealed.
A configuration of a few examples may be used. When the air chamber 69b is sealed,
When oil flows into the oil chamber 69a from the hydraulic cylinder 10
Since the pressure in the air chamber 69b increases, the oil
From the air chamber 69b when returning to the hydraulic cylinder 10 from
Easily flows into the hydraulic cylinder 10 by force,
The lowering speed of the unit 7 can be increased. Also oil
Is pressurized, so that the oil chamber 69a does not become a vacuum.
In addition, there is no possibility that air enters the hydraulic cylinder 10. First
An example is shown in FIG.
The oil tank 80 communicates with the oil tank 80 through a conduit 81. tube
Road 81 reaches the upper revolving superstructure 9 along the boom 2 and
Communicating with an oil tank 80 provided in the revolving superstructure 9.
You. The space for storing the oil tank 80 in the third arm 5
This example may be applied when there are no resources. The second example is shown in FIG.
(B) As shown in FIG.
The air chamber 84 communicates with the air line 85. Third stage arm
5, there is a storage space for the air chamber 84, and the oil is always in the oil chamber.
The multi-stage telescopic arm 90 works
This is applied when the operation is performed, and is
Since the attached piston 70 becomes unnecessary, it becomes an inexpensive oil sump.
You. Note that the conduit 85 extends along the boom 2 to the upper revolving unit 9.
May have been reached. The third example is shown in FIG.
The oil reservoir 86a and the air chamber 86b are in an integrated container.
Is stored in the accumulator 86. By this
Thus, the oil sump subtank becomes compact. FIG. 6 shows the location of the oil chamber of the oil sump.
The first and second examples of the hydraulic cylinder 10
Attached end 10b is integrated with tube
The hydraulic cylinder 10 and the oil sump 6
9 is short and effective. The first example is shown in FIG.
As shown in FIG.
Arrange substantially parallel to the side of the tube adjacent to the tube.
Many of the third-stage arms 5 have a rectangular cross-section.
By placing the cylinder 10 and the oil chamber 87 in parallel,
Efficient use of space and no need to prepare extra space
A compact oil sump is obtained. Oil chamber 87 with multiple oils
The chamber may be divided and placed adjacent to the tube. Second
In the example, as shown in FIG.
It is located below the tube of the die 10. Third stage arm 5
Has a space below the tube of the hydraulic cylinder 10.
Often use space effectively.
There is no need to prepare space for a compact oil sump
Can be The oil chamber 87 is divided into a plurality of oil chambers,
It may be arranged below. The third example is shown in FIG.
The oil chamber 89 covers the tube of the hydraulic cylinder 10
And formed integrally with the hydraulic cylinder 10
Deploy. Oil chamber 89 is installed at the same time as hydraulic cylinder 10
As a result, the assemblability of the multi-stage telescopic arm 90 is improved.
Also, a mounting seat or the like is provided for mounting the oil chamber 89.
Since there is no need, an inexpensive multi-stage telescopic arm 90 can be obtained. In the present invention, the hydraulic cylinder 1
0 bottom chamber 10y and oil chamber 69a of oil reservoir 69 are connected.
It is said that. To support the weight of each arm 4,5
In the head chamber 10x of the hydraulic cylinder 10, for example, several tens
Atmospheric pressure is constantly being generated. Position b of the operating valve 11
When operating and lowering the clam bucket 7,
The oil in the head chamber 10x is supplied to the operation valve 11 by the hydraulic pressure of 10 atm.
, And the tank 6 is drained rapidly. On the other hand,
Although oil flows into the bottom chamber 10y from the pump 19,
Because the flow rate is not enough for the descent speed, the bottom chamber
10y is in a vacuum state, oil is sucked from the oil reservoir 69,
Has a fast descending speed. Thus, a vacuum is created.
The easily accessible bottom chamber 10y and the oil reservoir 69 are connected. FIG.
As shown in FIG.
Each arm with the step extendable arm 90 turned obliquely upward
When working to reduce the stroke of 4, 5
The head chamber 10x of the cylinder 10 is easily evacuated. this
When there are many such operations, as shown in FIG.
The oil chamber 69a of the oil reservoir 69 is connected to the head chamber 10x. This
As a result, a vacuum in the head chamber 10x can be prevented, and the clamba
The speed of the ket 7 can also be secured. The multi-stage telescopic arm 9
The oil chamber 69a of the oil sump 69 is
To connect to the storage chamber 10x or the bottom chamber 10y.
It may be interchangeable. In this embodiment, the pilot
Check valve 62 is arranged between bottom chamber 10y and oil sump 69.
The normal check valve 91 as shown in FIG.
And the pilot switching valve 92 in combination to
The check valve 62 may be used instead. That is, the bottom chamber 1
When 0y is a negative pressure, the oil flows from the oil reservoir 69 to the bottom chamber 10y.
And the supplied hydraulic pressure P3 of the head chamber 10x is predetermined.
When the value is equal to or more than the value, the pilot switching valve 92
To drain oil from the bottom chamber 10y to the oil sump 69.
You. Also, when the hydraulic cylinder 10 contracts,
The cylinder 10 is extended and the hydraulic pressure in the bottom chamber 10y is negative.
When pressure is applied, the bottom chamber 10y communicates with the oil sump 69,
The cylinder 10 is extended and the hydraulic pressure in the bottom chamber 10y is positive.
When the control valve is controlled to
It may be used instead of the lot check valve 62. As described above, according to the present invention, the working machine is mounted
Telescopic multi-stage telescopic arm and inside of multi-stage telescopic arm
Hydraulic system that controls the expansion and contraction of the multi-stage telescopic arm
Oil is sent to the cylinder and the hydraulic cylinder, and the hydraulic cylinder expands and contracts.
Operating valve to switch oil and oil located near the hydraulic cylinder
Supplying the sump and the bottom chamber of the hydraulic cylinder
Oil from the bottom chamber depending on whether it is smaller or larger than
Via a pilot check valve that blocks and circulates oil flow to the sump
When the cylinder is compressed, the hydraulic valve
Oil to the head chamber of the
Bottom due to oil pressure in the head chamber that is larger than the specified value supplied
Circulates the oil flow from the chamber to the sump
When the cylinder is extended, the oil in the head chamber passes through the operation valve.
And drain, and pilot the oil collected in the oil sump
Return to bottom chamber via check valve. This allows the head
Large volume in the bottom chamber that requires almost twice the flow rate
Oil flows directly into and out of the sump, and the pressure
The power loss is due to the hose that passes the oil in and out of the head chamber
Pressure loss can be reduced
You. This can increase the oil flow rate
Work machine that can increase and decrease the expansion and contraction speed of the hydraulic cylinder
Speed is obtained. Also, for example, oil to be supplied to the bottom chamber
When the pressure cylinder is extended, the load on the work machine is
When acting in the direction
Oil is supplied to the bottom chamber, so a large elongation speed can be secured.
Wear. At this time, the oil discharged from the head chamber to the tank
The flow rate is controlled, for example, by an operating valve operated by the operator.
Therefore, it becomes meter-out control and has excellent speed controllability.
A working machine hydraulic circuit is obtained. In addition, the hydraulic cylinder
When the oil discharged from the head chamber is sent to the bottom chamber during extension
Since there is no regeneration circuit, a relief valve for the regeneration circuit
Work that is easy to adjust because tuning of the check valve is unnecessary
The hydraulic circuit of the machine is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hydraulic circuit according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of a pressure loss when a clam bucket moves up and down in the first embodiment. FIG. 3 is a hydraulic circuit of a second embodiment according to the present invention. FIG. 4 is an explanatory diagram of a pressure loss when a clam bucket moves up and down in a second embodiment. FIG. 5 is an explanatory view of an oil chamber of a sealed air chamber type. FIG. 6 is an explanatory diagram of an arrangement position of an oil chamber of an oil reservoir. FIG. 7 is an explanatory diagram when the oil chamber of the oil reservoir is connected to the head chamber. FIG. 8 is an explanatory diagram of another example of the hydraulic circuit between the oil reservoir and the bottom chamber. FIG. 9 is an explanatory diagram of a work machine that performs a deep foundation excavation operation. FIG. 10 is an explanatory diagram of a multi-stage telescopic arm. FIG. 11 is a hydraulic circuit diagram of the multi-stage telescopic arm. FIG. 12 is an explanatory diagram of pressure loss at the time of raising and lowering a clam bucket. [Description of Signs] 1 ... Work machine, 2 ... Boom, 3 ... Base arm, 3g ... Boom mounting part, 4 ... Second stage arm, 5 ... Third stage arm, 6
... tank, 7 ... clam bucket, 8 ... lower traveling body, 9 ...
Upper revolving unit, 10 ... hydraulic cylinder, 10a ... rod attachment end, 10b ... tube attachment end, 10x ... head chamber, 10
y: bottom chamber, 11: operating valve, 12: relief valve, 1
3, 15 ... pilot check valve, 14 ... relief valve,
16 ... Counter balance valve, 16a ... Check valve, 16
b ... pressure regulating valve, 17 ... variable throttle, 18 ... pilot check valve, 19 ... hydraulic pump, 20 ... discharge line, 21a ... downstream line, 21aa ... line, 21b ... head side line, 2
2a: downstream pipe, 22b: bottom pipe, 23: operating lever, 24: branch pipe, 25, 26: pipe, 29, 3
0, 31 ... drain pipe, 35, 36, 37, 72 ... throttle, 43, 44, 45, 46 ... pilot pipe, 50,
52 ... fixed sheave, 51, 53 ... wire rope, 51
a, 51b, 53a, 53b connection end, 60 ... relief valve, 61 ... check valve, 62, 68a ... pilot check valve, 64, 65 ... pipeline, 68 ... counterbalance valve, 68b ... pressure regulating valve, 69 ... oil Reservoir, 69a, 82, 86
a, 87, 88, 89 ... oil chamber, 69b, 84, 86b ...
Air chamber, 70: piston, 71: vent hole, 80: oil tank, 81, 85: conduit, 86: accumulator,
90: multi-stage telescopic arm, 91: check valve, 92: pilot switching valve, V: flow rate, k: constant, ΔPu1, ΔPu
2, ΔPuc ... pressure loss.

Claims (1)

Claims: 1. A hydraulic circuit of a working machine for controlling a working machine, comprising: a telescopic multistage telescopic arm (90) to which a working machine (7) is attached.
And a hydraulic cylinder (10) mounted inside the multi-stage telescopic arm (90) to control the expansion and contraction of the multi-stage telescopic arm (90), and to switch the expansion and contraction of the hydraulic cylinder (10) by supplying oil to the hydraulic cylinder (10) An operation valve (11) and an oil sump (69) arranged near the hydraulic cylinder (10) are provided. The oil sump (69) and the bottom chamber (10y) of the hydraulic cylinder (10) are connected to the operation valve (11). ) From the bottom chamber (10y) to the oil sump (69) through a pilot check valve (62) that shuts off and circulates the oil flow according to the oil pressure supplied to the head chamber (10x). 10) Hydraulic cylinder from operating valve (11) during contraction
Oil is supplied to the head chamber (10x) of (10) and the head chamber (10
The oil flow from the bottom chamber (10y) to the oil sump (69) is circulated by the oil pressure (P3) on the x) side, the oil is discharged from the bottom chamber (10y) to the oil sump (69), and the hydraulic cylinder (10) The oil in the head chamber (10x) is an operating valve during extension.
A hydraulic circuit for a working machine, wherein the hydraulic circuit drains through (11) and returns the oil stored in an oil sump (69) to a bottom chamber (10y) via a pilot check valve (62).