JP2003278705A - Drive-controlling unit for work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a situation where the derricking speed of a boom decreases due to the influence of the load pressure of a swivel base when the compound operation of the turning movement of the swivel base and the derricking motion of the boom is made. <P>SOLUTION: A drive-controlling unit 40 comprises a slewing motor 12, a rotary drive-controlling valve 41 for controlling the drive of a boom cylinder 31 and an arm cylinder 33, a boom drive-controlling valve 51, and an arm drive- controlling valve 61. A first oil channel 42, a second oil channel 52, and a third oil channel 62 are connected between the drive-controlling valves and the actuators 12, 31, and 33. Then, a first pressure-compensating valve 47, a second pressure-compensating valve 57, and a third pressure-compensating valve 67 are provided in the oil channels 42, 52, and 62. A second pilot oil channel 54 is connected to the second oil channel 52, and then a pilot pressure-switching valve 80 allowing the second pilot oil channel 54 to communicate with the second pressure-compensating valve 57 when the allowable maximum load pressure is operated while working oil hydraulics are being operating on the boom cylinder 31 is provided to the second pilot oil channel 54. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a working vehicle.
In more detail, it is possible to turn on a traveling body
And a swivel provided on the swivel
The boom and the boom tip
Drive control device for a working vehicle that controls the drive of
You. 2. Description of the Related Art A working vehicle constructed as described above has a
Used when excavating or moving excavated soil
In many cases, a swingable pivot is connected to the tip of the arm.
Some are configured with a socket. [0003] A driving cabinet is mounted on a turntable of such a working vehicle.
The operator is seated in a chair in the driving cabin
Boom, arm and bucket drive operation possible
Operating devices are provided. The operating device rotates the swivel
First operation for turning the arm and bending and extending the arm
Move the lever and boom up and down and lift the bucket
A second operation lever for swinging operation, the first operation lever
And the second operation lever is configured to be tiltable in the front, rear, left and right directions.
Have been. The first operating lever tilts forward and backward
When operated, the arm bends and extends upward, and the first operation lever
Arm is tilted backward in the front-rear direction, the arm bends downward.
Extends and the first operation lever is tilted to the left in the left-right direction.
When the turntable turns left, the first operating lever moves left and right.
When the tilting operation is performed to the right side, the swivel base turns right.
Is configured. A first operating lever and a second operating lever
Can be tilted in an oblique direction. For example, the first operation
When the lever is tilted forward and diagonally right, the swivel
The arm will bend rightward while turning right.
As described above, the operating device enables a so-called composite operation.
It is configured. Here, the vehicle is turned according to the operation of the operating device.
Drive control device that controls the drive of the base, boom and arm
This will be described with reference to FIG. FIG. 3 shows the drive control device.
The configuration is shown, and as shown in FIG.
A swivel motor 12 for swiveling the table and a boom
Boom cylinder 31 and an arm for bending and extending the arm
Cylinder 33, variable displacement hydraulic pump P, and swivel
Motor 12, boom cylinder 31, and arm cylinder 3
3 and provided from the hydraulic pump P.
Turning drive control valve 4 for controlling the supply and discharge of supplied oil
1. Boom drive control valve 51 and arm drive control valve
Boss 61. Swing drive control valve 41, boom drive control
The valve 51 and the arm drive control valve 61 are pump hydraulic oil.
It is connected to a hydraulic pump P via a passage 70. Swivel drive
The control valve 41 is connected via a first oil passage 42 for supplying an operating oil pressure.
And selectively connected to the swing motor 12 for boom drive control
The valve 51 is connected to the boom cylinder 31 via the second oil passage 52.
Selectively connected to the bottom chamber 31a and the rod chamber 31b.
The arm drive control valve 61 is connected via a third oil passage 62
Bottom chamber 33a and rod chamber 33 of arm cylinder 33
b. 1st oilway 4
2. Each of the second oil passage 52 and the third oil passage 62 has the first
The pilot oil passage 44, the second pilot oil passage 54, the third
The pilot oil passage 4 communicates with the pilot oil passage 64.
4, 54, 64 operate three shuttle valves 45, 55, 65
Through the regulator valve R. Regular
Data valve R has three shuttle valves 45, 55, 65
These pilot oil passages 44, 54, 64
The hydraulic pressure with the highest hydraulic pressure among the hydraulic pressures in the
Pressure ". ) As a pilot pressure regulator pie
It works via the lot oil passage 71. Regulator bar
Lube R is determined by the pump pressure in the pump pressure oil passage 70 and the above-described minimum pressure.
Maximum load so that the differential pressure from the high load pressure becomes a predetermined constant value
Connected to the swash plate S of the hydraulic pump P according to the magnitude of the pressure
Changing the inclination of the swash plate S by extending and contracting the capacity cylinder 72
It is configured to change the capacity of the hydraulic pump P.
You. Further, the first oil passage 42, the second oil passage 52, and the
Each of the three oil passages 62 has a first pressure compensating valve 47,
2 A pressure compensating valve 57 and a third pressure compensating valve 67 are provided.
And these pressure compensating valves 47, 57, 67
The maximum load pressure mentioned above acts as pilot pressure.
Pressure regulator branched from regulator pilot oil passage 71
The compensation pilot oil passage 79 is connected. These pressures
The compensating valves 47, 57, and 67 are movably provided switches.
It is equipped with a pool valve, and a pressure compensation valve is provided on one side of this spool valve.
The hydraulic pressure flowing into the lubes 47, 57, 67 acts,
Pressure compensation valves 47, 57, 67 on the other side of the
The spring pressure of the spring 74 applied and the pilot pressure act,
The spool valve moves due to the pressing of these oil pressures,
The first oil passage 42, the second oil passage 52, and the third oil passage 62
It is configured to shut off. [0008] According to the drive control device configured as described above,
For example, the swing motor 12, the boom cylinder 31, and the arm
Linda 33 (hereinafter collectively referred to as “Actuate
Ta ". Load acts on at least one of
And the one with the largest load
Oil is supplied from the hydraulic pump P so that the tuator can be driven.
Discharges only the required flow rate and responds to this largest load
Swing drive control valve with maximum load pressure as pilot pressure
41, boom drive control valve 51 and arm drive control valve
Acts on each of the lubs 61. For this reason, the operating device
Example of combined operation of actuator and actuator
For example, the swivel base swings and the boom raises
Below, it is described as “hoist operation”. ), While turning
When a large load acts on the base 11, the capacity of the hydraulic pump P
Is increased, and the turning motor 12 subjected to a large load
Oil is updated from the hydraulic pump P by the required flow rate so that it can be driven.
To be discharged. Here, the oil discharged from the hydraulic pump P
Is the first oil upstream of the first pressure compensation control valve 47.
The pressure in the path 42 'is increased to increase the pressure in the first pressure compensation control valve.
The spool valve in the valve 47 is moved in the valve opening direction, and the first pressure
The compensation control valve 47 is opened. Therefore, the first
The oil passage 42 'is in a communicating state, and the pressurized oil is turned.
The rotation is supplied to the rotation motor 12 through the control valve 41,
The rotation motor 12 rotates against the load. Meanwhile, hydraulic pon
The oil discharged from the pump P is supplied to the second pressure compensation control valve 57.
By increasing the oil pressure in the second oil passage 52 'on the upstream side,
Opening the spool valve in the second pressure compensation control valve 57
And the second pressure compensation control valve 57 is opened.
I do. Therefore, the second oil passage 52 'is in a communicating state, and
The pressurized oil is supplied to the boom via the boom drive control valve 51.
The boom cylinder 31 is extended by being supplied to the cylinder 31.
Then, the boom operates with the hoist. The oil discharged from the hydraulic pump P as described above
Is the first pressure compensation control valve 47 and the second pressure compensation control
It is supplied to the valve 57, but temporarily connected to the swing motor 12.
A first pressure compensation control valve 47 is provided in the first oil passage 42.
Assuming that the motor is not
Load causes the second pressure compensation control valve 57 to open.
When the pressure is smaller than the load pressure, discharge from the hydraulic pump P
Most of the oil that has fallen tries to flow into the turning drive control valve 41.
You. As a result, upstream of the second pressure compensation control valve 57
The pressure increase speed of the oil in the second oil passage 52 ′ on the
The opening area of the force compensation control valve 57 does not increase,
As a result, the extension movement of the boom cylinder 31 becomes slow (boom
The hoist operation slows down). Therefore, the first oil passage 42
A first pressure compensation control valve 47 is provided to perform first pressure compensation control.
The hydraulic pressure in the first oil passage 42 ′ upstream of the valve 47 is minimized.
The second pressure compensation control is maintained at a predetermined pressure exceeding the high load pressure.
The oil pressure of the oil flowing into the valve 57 can be increased
Then, the first pressure compensation control valve 47 is opened with a large opening area.
I try to give it a valve. For this reason, exceeding the maximum load pressure
The predetermined hydraulic pressure can be supplied to the boom cylinder 31.
To prevent the extension speed of the boom cylinder 31 from decreasing.
I have. In addition, the boom cylinder 31
The second oil passage 52 connected to the arm cylinder 33 and the second oil passage 52
The third oil passage 62 has the same function as the first pressure compensation control valve 47.
The second pressure compensation control valve 57 and the third pressure compensation control valve
A valve 67 is provided. [0011] However, the second pressure
The force compensation control valve 57 uses the maximum load pressure as the pilot pressure.
The swivel table is swiveled
When turning the boom and hoisting the boom,
A large load acts on the table and a predetermined lower pressure than the relief pressure
Allowable load pressure acts on the second pressure compensation control valve 57
Then, the second oil downstream of the second pressure compensating valve 57
The hydraulic pressure in the passage 52 is released by the second pressure compensating valve 57.
Pressure and less than the maximum allowable load pressure and the second pressure compensation
Slightly greater than the total spring pressure of the spring 74 of the valve 57
Hydraulic pressure. As a result, the second pressure compensation control valve
The spool valve No. 57 is in the state of pushing each other.
(2) The pressure compensation control valve 57 is slightly opened.
You. For this reason, the supply amount of oil to the boom cylinder 31 is low.
Lower, the boom raising speed (boom hoist operation)
The problem that it becomes slow arises. The arm cylinder 33 is also a boom syringe.
As in the case of the dam 31, the swivel is swiveled and
When the arm is bent and extended,
When the arm is bent and extended while a heavy load is acting,
It is said that the supply amount of hydraulic oil to the arm cylinder is reduced
Although a problem occurs, the capacity of the arm cylinder 33 is
Since the arm is smaller than that of Linda 31, the bending and extension of the arm
The degree to which the speed is slow is small, and it will not be a big problem
No. The present invention has been made in view of such a problem.
It is a combination of the swiveling motion of the turntable and the raising motion of the boom.
When joint operation is performed, the load pressure
The drive of a work vehicle that does not slow down the boom
It is an object to provide a dynamic control device. [0014] In order to solve the above-mentioned problems,
The drive control device for a work vehicle according to the present invention
The traveling carriage 7) according to the embodiment is provided so as to be pivotable.
A swivel, a swivel motor for swiveling the swivel, and a swivel
The boom is provided to be able to move up and down, and the boom is
Boom cylinder and the boom tip
An arm that is freely provided and an arm that flexes and extends the arm
(For example, in the embodiment)
1) the drive control device of the backhoe
Hydraulic pump, swing motor, boom cylinder and
Hydraulic ports are provided for each of the arm cylinders.
Swing drive control that controls the supply and discharge of oil supplied from the pump
Valve, boom drive control valve and arm drive control valve
, Hydraulic pump and swing drive control valve, boom drive control
Pump pressure oil connecting control valve and arm drive control valve
Road, swing drive control valve and swing motor connected to operate
A first oil passage for supplying hydraulic pressure, a boom drive control valve and a boom drive control valve;
Second connecting the rod chamber or bottom chamber of the cylinder
Oil passage, arm drive control valve and arm cylinder bottom
A third oil passage connecting the chamber or the rod chamber, a first oil passage,
1st Pyro linked to each of 2nd oilway and 3rd oilway
Cut oil passage, second pilot oil passage, and third pilot oil passage
And the first pilot oil passage, the second pilot oil passage and
And the third pilot oil passage.
Depending on the highest load pressure, which is the highest in the road,
Supplied from a hydraulic pump by changing the capacity of the pressure pump
By adjusting the oil supply, the oil pressure of the pump oil passage and the maximum load
Oil supply amount adjusting means for making the pressure difference with the pressure a predetermined constant value
(For example, the capacity cylinder 72 in the embodiment, the regulation
, A first oil passage, a second oil passage, and a third oil passage.
And the maximum load pressure is used as the pilot pressure.
Receiving the swing motor, boom cylinder and arm
Oil to be supplied to the specified pressure exceeding the maximum load pressure
1st pressure compensating valve, 2nd pressure compensating valve and 3rd pressure compensating valve
A pressure compensation valve and a pump pressure oil passage.
Relief to prevent hydraulic pressure from exceeding a specified relief pressure
A valve (for example, the relief valve 77 in the embodiment);
And is provided in the second pilot oil passage and has a relief pressure
The maximum allowable load pressure at the specified low pressure is received as the maximum load pressure.
Raise the boom with the boom cylinder
When the operating hydraulic pressure in the direction is supplied, the second pilot oil
Oil passage connection for connecting the passage to the second pressure compensating valve
Communication means (for example, the pilot pressure switching valve in the embodiment)
80, a sequence valve 83), and a second pressure compensating valve.
Is the second pilot oil passage by the pilot oil passage communication means.
Via the hydraulic pressure acting on the boom cylinder
Supply from the boom drive control valve to the boom cylinder
Set the oil pressure of the starting oil to a predetermined oil pressure that exceeds the operating oil pressure
It is configured as follows. According to the drive control device having the above configuration, the second drive
Let this communicate with the second pressure compensating valve to the Illot oil passage
By providing pilot oil passage communication means
Boom syringe while turning against heavy loads
The hydraulic pressure in the direction to raise the boom is supplied to the damper
And the pilot oil passage communicating means is connected to the second pressure compensating valve.
Cut off the operation of the allowable maximum load pressure, and
It communicates with the second pressure compensating valve. Therefore, the second pressure compensation
The compensation valve is supplied from the hydraulic pump to the second pressure compensation valve
The second pilot oil passage by the
Second pressure compensating valve against total pressure of dynamic hydraulic pressure and spring pressure
The built-in spool valve is moved to increase the opening area.
Open the valve in the right condition. As a result, hydraulic oil
Hydraulic oil at a specified pressure exceeding the pressure
The boom cylinder does not reduce the boom raising speed.
Naturally, it can be prevented. Preferred embodiments of the present invention will be described below.
The state will be described with reference to FIGS. In this embodiment,
Used when excavating the ground or moving excavated soil, etc.
FIG. First, the drive according to the present invention
Before explaining the control device, this drive control device was installed
The backhoe will be described. Backhoe 1 is shown in FIG.
As shown, a traveling device 5 having a pair of right and left crawler tracks 3 is provided.
The traveling trolley 7 is mounted on the traveling trolley 7 so as to be pivotable.
Swivel 11 and power pivoted to the front of swivel 11
An excavator device 20 and an oscillating device
And a pererator cabin 15. The swivel 11 is attached to FIG.
The swing drive can be performed by the swing motor 12 shown. power
The excavator device 20 has a base end located below the front end of the swivel 11.
A boom 25 that is pivoted and swingable up and down, and this boom
Arm 27 pivotally connected to the tip of 25 and swingable up and down
And a bar pivotally connected to the tip of the arm 27 so as to be swingable up and down.
And a socket 29. Boom 25 turns
Pivotally connected between the lower front end of the turntable 11 and the lower surface of the boom 25
It can be moved up and down by the boom cylinder 31 and the arm 2
7 is pivotally connected between the upper surface of the boom 25 and the base of the arm 27.
The arm cylinder 33 can bend and extend, and the bucket
G is pivoted between the upper surface of the arm 27 and the base of the bucket 29.
It can swing up and down by the connected bucket cylinder 35.
is there. A power system is installed in the operator cabin 15.
An operator (not shown) sitting facing the leveling device 20
A lator sheet 17 is provided. Operator cab
From the operator seat 17
Also at the front end in the front-rear direction (power shovel device 20 side)
Is a pair of travel control levers that operate the drive of the left and right crawler tracks 3
19 are provided. To the left and right of the operator seat 17
Is an operating device 2 for operating the drive of the excavator device 20
1 is provided. The operating device 21 is a left operating lever 21
a and a right operating lever 21b.
21a and 21b are configured to be able to tilt forward, backward, left and right.
You. The left operating lever 21a is located on the front side in the front-rear direction.
The arm 27 bends and extends upward,
When the operation lever 21a is tilted rearward in the front-rear direction,
Arm 27 bends and extends downward, and the left operating lever 21a moves to the left.
When the tilting operation is performed to the left in the right direction, the turntable 11 performs a left turning operation.
Then, the left operation lever 21a is tilted right and left in the left and right direction.
Then, the turntable 11 is configured to perform a right turn operation.
You. On the other hand, the right operating lever 21b is
When the tilt operation is performed, the boom 25 falls down and the right operation lever is turned.
-21b is tilted rearward in the front-rear direction, the boom 25
Is raised, and the right operating lever 21b is tilted leftward in the left-right direction.
When the bucket 29 is operated, the bucket 29 excavates and the right operation lever is operated.
-21b is tilted to the right in the left-right direction, the bucket 2
9 is configured to perform a soil discharging operation. The operating device 21 includes a left operating lever 21.
a and the right operation lever 21b can be tilted obliquely.
For example, the left operation lever 21a
When the tilting operation is performed, the swivel table 11 performs a right turning operation.
The arm 27 is configured to bend and extend upward.
You. The above-described power shovel device 20 operates
A drive that controls its operation in response to an operation signal from the device 21
Connected to the motion controller. The drive control device 40
2, the swing motor 12 and the boom cylinder 3
1, the arm cylinder 33, and the inclination of the swash plate S by changing the inclination.
Variable displacement type hydraulic pump P for changing the amount and swing motor 1
2. Boom cylinder 31 and arm cylinder 33
Provided corresponding to each and supplied from the hydraulic pump P
A swing drive control valve 41 for controlling supply and discharge of hydraulic oil,
Arm drive control valve 51 and arm drive control valve 61
And is configured. Swing drive control valve 41, boom drive control
The valve 51 and the arm drive control valve 61 have 7 ports
It is a three-position directional switching valve, which is connected via a pump pressure oil passage 70.
Each is connected to the hydraulic pump P. Swing drive control
The valve 41 is connected to a first oil passage 42 that supplies the operating oil pressure.
The first oil passage 42 is connected to the turning motor 12 and the turning drive control valve.
And a pair of turning communication oil passages 43, 43 'communicating between the
Connected selectively. The boom drive control valve 51 is
The second oil passage 52 is connected to a second oil passage 52 that supplies dynamic oil pressure.
Is the bottom chamber 31a of the boom cylinder 31 and the rod chamber 3
1b to a pair of boom communication oil passages 53, 53 'communicating with each other.
Connected selectively. The arm drive control valve 61 is
The third oil passage 62 is connected to a third oil passage 62 that supplies dynamic oil pressure.
Is the bottom chamber 33a of the arm cylinder 33 and the rod chamber 3
3b to a pair of arm communication oil passages 63, 63 'communicating with each other.
Connected selectively. These drive control valves 41,
A discharge oil passage 75 communicating with the tank T is connected to 51 and 61.
The discharge oil passage 75 and the pump pressure oil passage 70 are connected to the relief oil passage 8.
6 to the relief oil passage 86 and the pump pressure oil passage 7
Relief that the oil pressure of 0 does not exceed the specified relief pressure
A leaf valve 77 is provided. The first oil passage 42, the second oil passage 52, and the third oil passage
The first pilot oil passage 44 and the second pie
The lot oil passage 54 and the third pilot oil passage 64 communicate with each other.
You. The first pilot oil passage 44 includes a first shuttle valve 45 and
Third pilot oil via the first communicating pilot oil passage 46
Connected to the third shuttle valve 65 connected to the
The ilot oil passage 54 is connected to the second shuttle valve 55 and the second communication path.
Connected to the first shuttle valve 45 via the ilot oil passage 56
The third pilot oil passage 64 is connected to the third shuttle valve 65 and
It is connected to the third communication pilot oil passage 66. Third communication
The pilot oil passage 66 controls the inclination of the swash plate S of the hydraulic pump P.
Regulator pie connected to regulator valve R to control
It is connected to the lot oil passage 71. First shuttle valve 45, second shuttle valve 55
And the third shuttle valve 65 has a high hydraulic pressure acting on it.
Hydraulic pressure to the communicating pilot oil passages 46, 56, 66.
It is configured as follows. Therefore, the regulator valve
Selectable with three shuttle valves 45, 55, 65
Hydraulic pressure in the three pilot oil passages 44, 54, 64
Of the highest hydraulic pressures (hereinafter referred to as “maximum load pressure”)
You. ) Will act as pilot pressure. Legi
The pressure of the pump pressure in the pump pressure oil passage 70
The differential pressure from the maximum load pressure described above should be a predetermined constant value.
To the swash plate S of the hydraulic pump P according to the maximum load pressure
The swash plate S is controlled by controlling the expansion and contraction of the connected capacity cylinder 72.
Is changed to change the capacity of the hydraulic pump P. What
Oh The rotation speed of the hydraulic pump P is constant, and the inclination of the swash plate S is
Changes the amount of oil discharged from the hydraulic pump P
You. First oil passage 42, second oil passage 52, and third oil passage
A first pressure compensating valve 47 and a second pressure
A compensation valve 57 and a third pressure compensation valve 67 are provided.
ing. These pressure compensating valves 47, 57, 67 are throttled.
2 port 2 position shut-off valve
To open an opening (not shown) formed therein.
(Not shown) movably arranged to close and close
Equipped with a valve. These pressure compensating valves 47, 5
Reference numerals 7 and 67 denote operations of hydraulic oil supplied from the hydraulic pump P.
Hydraulic pressure acts on one end of the spool valve and the pressure compensation valve
And the spring pressure of a spring 74 provided in the
Total pressure with maximum load pressure acts on the other end of the spool valve
When the operating oil pressure is greater than the total pressure, the spool valve
Move to open the opening to connect the oil passages 42, 52, 62.
Through the spool valve when the operating oil pressure is smaller than the total pressure.
Moves to close the openings and shut off the oil passages 42, 52, 62
It is configured to The opening has a predetermined area.
Pressure difference between the working oil pressure and the total pressure
When the value exceeds the value, all of the openings are open,
And all of the openings are closed. First pressure compensation valve 47 and third pressure compensation
The valve 67 is provided with a regulator pie for the maximum load pressure described above.
Pressure compensating pilot oil passage 7 branched from lot oil passage 71
9 to act as pilot pressure
ing. A second pilot oil passage connected to the second oil passage 52
54 and a pressure compensation valve connected to the second pressure compensation valve 57.
Pilots that straddle these oil channels
A pressure switching valve 80 is provided. Pilot pressure switching valve
At 80, a branch branched from the pressure compensation pilot oil passage 79
The pilot oil passage 81 is connected, and the branch pilot oil passage 81 is connected.
Is provided with a sequence valve 83 and a throttle valve 84 from the upstream side.
Have been killed. Boom communication with sequence valve 83
The communication pilot oil passage 85 connected to the oil passage 53 is connected
I have. This sequence valve 83 is connected to the boom cylinder 31
A predetermined pressure is applied from the boom drive control valve 51 to the bottom chamber 31a.
When the hydraulic oil exceeds
Operating hydraulic pressure acting on the arm cylinder 31 (hereinafter, this hydraulic pressure
Is referred to as “boom load pressure”. ) Is communicating pilot oil passage 8
When the state that the sequence valve 83 is actuated via 5 is obtained,
The branch pilot oil passage 81 communicates with the boom cylinder 3
When the boom load pressure acting on 1 is smaller than the predetermined pressure
Cuts off the branch pilot oil passage 81,
Pilot oil selectively according to the load pressure
The road 81 is configured to communicate and shut off. The pilot connecting to the branch pilot oil passage 81
The pressure switching valve 80 is a 4-port 2-position directional switching valve.
When the sequence valve 83 is open and the branch pipe
A predetermined pressure lower than the relief pressure through the lot oil passage 81
When receiving the maximum allowable load pressure, the second pressure compensating valve 57
Cut off the connected pressure compensating pilot oil passage 79
The lot oil passage 54 communicates with the second pressure compensating valve 57,
When the sequence valve 83 is closed, the pressure is compensated.
Pilots the maximum load pressure by communicating with the
Pressure to act on the second pressure compensating valve 57
It is configured. 2nd pressure compensation valve 57 and pilot
The pressure compensating pilot oil passage 79 connecting the pressure switching valves 80
A throttle valve 88 is provided. Next, the operation of the drive control device 40 will be described.
While the swivel table 11 shown in FIG.
The case in which 5 is raised will be described. Note that the hydraulic
The pump P rotates by receiving driving force from an engine (not shown).
Set to be drivable. First, the swivel
The left operation lever 21a shown in FIG.
Is operated, the hydraulic oil discharged from the hydraulic pump P becomes
As shown in FIG. 2, the swing drive is performed through the pump pressure oil passage 70.
It is supplied to the control valve 41. Swing drive control valve 41
Is supplied to the first oil passage 42 and one of the slewing communication
The turning motor 12 is supplied through the oil passage 43. Further details
More specifically, the operating lever 21a is operated to
Drive control valve 41 so that hydraulic oil is supplied to
When activated, the hydraulic oil discharged from the hydraulic pump P turns
Via the drive control valve 41 to the first pressure compensation valve 47
Works. This operating oil pressure is applied to the first pressure compensating valve 47.
Larger than the combined pilot pressure and spring pressure
The first pressure compensating valve 47 opens, and as a result, the hydraulic pressure
The hydraulic oil from the pump P is supplied to the first oil passage 42 and one of
The oil is supplied to the turning motor 12 through the oil passage 43. Ma
In addition, another turning communication oil passage 43 ′ connected to the turning motor 12.
The oil inside passes through the turning drive control valve 41 and the discharge oil passage 75.
Is discharged to the tank T and the rotation motor 12 is driven to rotate.
You. Here, hydraulic oil is supplied to the swing motor 12.
The hydraulic pressure of the first oil passage 42 is transmitted to the first pilot oil passage 44.
Through the first shuttle valve 45 and the third shuttle valve 65
Leverage hydraulic pressure (hereinafter referred to as “maximum load pressure”) is regulated.
Regulator valve via the pilot oil passage 71
Acts on R as pilot pressure. Also regulator
The hydraulic pressure in the pump pressure oil passage 70 is applied to the valve R by the pump pressure pie.
Acts as pilot pressure via lot oil passage 76. Therefore, the regulator valve R is a pump
The oil pressure in the pressure oil passage 70 is the maximum load pressure and the regulator valve.
The hydraulic pressure will exceed the total pressure of the springs 87
The capacity cylinder 72 is extended and retracted. As a result, turning
The turning motor 12 rotates against the load acting on the motor 12.
The required flow rate that can be rolled is discharged from the hydraulic pump P. Here, the swivel table 11 shown in FIG. 1 is shown in FIG.
Where the relief pressure is lower than the relief pressure at which the relief valve 77 opens.
Load corresponding to the specified allowable maximum load pressure
Load ". ) Is working and rotating
Assuming that the boom 25 shown in FIG.
Consider the case where Allowed for swivel 11 shown in FIG.
When the maximum load is applied, the regulator valve R
The maximum allowable load pressure acting as the load pressure acts,
The lube R moves the capacity cylinder 72 to extend and retract to
Of the swash plate S is changed. As a result, the maximum allowable load
Hydraulic pump so that the swing motor 12 can rotate against the pressure.
The working oil is further discharged from the pump P by a required flow rate. Here, as shown in FIG.
A pressure compensating pilot oil passage 79 is directly connected to the valve 57.
Assuming that the second pressure compensating valve 5
7, the allowable maximum load pressure acts as the maximum load pressure
Become. This allowable maximum load pressure is a hydraulic pressure close to the relief pressure.
Therefore, the second oil passage 5 upstream of the second pressure compensating valve 57
Since the oil pressure of 2 does not exceed the relief pressure, the second oil
The hydraulic pressure of the passage 52 is higher than the total pressure of the allowable maximum load pressure and the spring pressure.
The hydraulic pressure slightly exceeds, and the pressure in the second pressure compensating valve 57
The spool valve (not shown) is in a pushing state.
Accordingly, the second pressure compensating valve 57 is slightly opened.
You. As a result, supply of hydraulic oil to the boom cylinder 31
The feed rate decreases, and the extension speed of the boom cylinder 31 decreases.
Will be. However, the drive control device according to the present invention
In the installation 40, as shown in FIG. 2, the turntable 11 shown in FIG.
The boom drive control valve 51 is
When operated to the ist side, first, the second pressure compensation valve
57 maximum allowable through pressure compensating pilot oil passage 79
Load pressure acts. Therefore, as described above, the second pressure compensation
The compensation valve 57 is slightly opened, and the boom communication
The oil passage 53 is in a state where the operating oil pressure is supplied. here
The hydraulic pressure (boom load pressure) of the boom communication oil passage 53 is communicated.
Guided by the pilot oil passage 85, this boom load pressure
The sequence valve 83 is opened and the pilot pressure switching valve is opened.
The maximum allowable load pressure will act on 80. The result
As a result, the pilot pressure switching valve 80 is connected to the second pilot oil passage 54.
To the second pressure compensating valve 57 so that the boom load pressure becomes the second pressure.
This acts on the force compensation valve 57. Further, on the downstream side of the second pressure compensating valve 57,
The hydraulic pressure of the connected second oil passage 52 can be raised to near the relief pressure
Supplied by the second pressure compensating valve 57
The hydraulic pressure of the operating oil is the difference between the boom load pressure and the spring pressure of the spring 74.
Larger with at least a predetermined differential pressure than the total pressure
Become. Therefore, the spool valve of the second pressure compensating valve 57
(Not shown) is in the pushed-out state, and the second pressure compensation
The opening of the valve 57 is largely opened, and the boom communication oil passage 5 is opened.
The supply amount of the working oil flowing into the fuel tank 3 can be increased.
As a result, it acts on the bottom chamber 31a of the boom cylinder 31.
Operating hydraulic pressure can be quickly increased to the desired hydraulic pressure.
And the raising speed (hoist speed) of the boom 25 shown in FIG.
Can be prevented beforehand. In addition,
By a throttle valve 84 provided in the branch pilot oil passage 81
Allowable maximum load pressure acts rapidly on pilot pressure switching valve 80
And gradually rises to the pilot pressure switching valve 80.
Pilot pressure is applied, the maximum allowable with a time difference
The load pressure acts on the pilot pressure switching valve 80. others
The pilot pressure switching valve 80 gradually switches,
System load pressure suddenly acts on the second pressure compensating valve 57,
To prevent a sudden change in the expansion and contraction speed of the arm cylinder 31
I have. In the embodiment described above, the pilot
Pressure switching valve 80, sequence valve 83, and throttle valve 84
Connected to the third pressure compensating valve 67 according to the pressure compensating valve 57
With such a configuration, when the swivel table 11 is swung,
The bending of the arm 27 when bending and extending the arm 27 together
A decrease in elongation speed can be prevented beforehand. As described above, the driving device of the present invention
According to the arrangement, this and the second pressure compensation are provided in the second pilot oil passage.
Provide pilot oil passage communication means for communicating with the valve
When the turntable is rotating against a large load,
The boom cylinder to raise the boom
When the hydraulic pressure is supplied, the pilot oil passage communication means operates at the second pressure.
Cut off the action of the allowable maximum load pressure on the force compensating valve,
The pilot oil passage communicates with the second pressure compensating valve. this
Therefore, the second pressure compensating valve is connected to the second pressure from the hydraulic pump.
The second hydraulic pressure is supplied to the compensation valve
Against the sum of the operating oil pressure and spring pressure of the
2 Move the spool valve built into the pressure compensation valve,
Open the valve with a large opening area. As a result,
A large amount of hydraulic oil with a predetermined pressure exceeding the operating oil pressure in the cylinder
Supplied in the condition, the boom raising speed by the boom cylinder
A decrease in the degree can be prevented beforehand.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a backhoe equipped with a drive control device according to the present invention. FIG. 2 shows a hydraulic circuit diagram of the drive control device according to the present invention. FIG. 3 shows a hydraulic circuit diagram of a conventional drive control device. DESCRIPTION OF SYMBOLS 1 Backhoe (working vehicle) 7 Traveling trolley (vehicle body) 11 Revolving base 12 Revolving motor 25 Boom 27 Arm 31 Boom cylinder 31a, 33a Bottom chambers 31b, 33b Rod chamber 33 Arm cylinder 40 Drive control device 41 Rotation drive Control valve 42 First oil passage 44 First pilot oil passage 47 First pressure compensation valve 51 Boom drive control valve 52 Second oil passage 54 Second pilot oil passage 57 Second pressure compensation valve 61 Arm drive control valve 62 Third oil Path 64 Third pilot oil path 67 Third pressure compensating valve 70 Pump pressure oil path 72 Capacity cylinder (oil supply amount adjusting means) 77 Relief valve (Relief valve) 80 Pilot pressure switching valve (Pilot oil path communicating means) 83 Sequence valve (Pilot oil passage communication means) P Hydraulic pump R Regulator valve (oil Supply amount adjusting means)

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 2D003 AA01 AB02 AB03 BA01 BA02                       BB02 CA02 DA03 DB02                 3H089 AA27 AA74 BB15 BB19 CC01                       CC08 CC11 DA03 DB03 DB14                       DB47 DB49 DB55 DB63 DB75                       EE03 EE14 EE15 EE23 FF07                       FF16 GG02 JJ02

Claims (1)

Claims: 1. A swivel provided on a vehicle body so as to be able to swing freely, a swing motor for swinging the swing base, a boom provided so as to be able to move up and down on the swivel, A drive control device for a work vehicle, comprising: a boom cylinder for raising and lowering a boom, an arm provided at a tip end of the boom so as to be able to bend and extend up and down, and an arm cylinder for bending and extending the arm. A variable displacement hydraulic pump, a swing drive control valve provided corresponding to each of the swing motor, the boom cylinder, and the arm cylinder, and a supply / discharge control of oil supplied from the hydraulic pump, a boom drive A control valve and an arm drive control valve, a pump pressure oil passage connecting the hydraulic pump with a swing drive control valve, a boom drive control valve and an arm drive control valve, Serial and turning drive control valve and first oil passage for supplying working oil pressure by connecting said swing motor, and a second oil passage that connects the rod chamber or bottom chamber of the boom cylinder and the boom driving control valve,
A third oil passage connecting the arm drive control valve to a bottom chamber or a rod chamber of the arm cylinder; and a first pilot oil connected to each of the first oil passage, the second oil passage, and the third oil passage. , The second pilot oil passage, the third pilot oil passage, and the first pilot oil passage, the second pilot oil passage, and the third pilot oil passage. The amount of oil supplied from the hydraulic pump is adjusted by changing the capacity of the hydraulic pump according to the highest load pressure having the highest hydraulic pressure, and the pressure between the hydraulic pressure of the pump pressure oil passage and the maximum load pressure is adjusted. An oil supply amount adjusting means for adjusting the difference to a predetermined constant value;
An oil passage provided in each of the second oil passage and the third oil passage, receiving the maximum load pressure as a pilot pressure, and supplying oil supplied to the swing motor, the boom cylinder, and the arm cylinder to the maximum load. A first pressure compensating valve, a second pressure compensating valve, and a third pressure compensating valve for providing a predetermined pressure exceeding the pressure, and the pump pressure oil passage is provided with a hydraulic pressure of the pump pressure oil passage exceeding a predetermined relief pressure. A relief valve for preventing the boom cylinder from being provided in the second pilot oil passage and receiving a maximum allowable load pressure lower than the relief pressure by a predetermined maximum pressure as the maximum load pressure. A pilot oil passage communicating means for communicating the second pilot oil passage with the second pressure compensating valve when an operating oil pressure in a direction for raising the boom is supplied; The second pressure compensating valve, when receiving the operating oil pressure acting on the boom cylinder via the second pilot oil passage by the pilot oil passage communicating means, supplies the operating oil pressure from the boom drive control valve to the boom cylinder. A drive control device for a working vehicle, wherein a hydraulic pressure of oil is set to a predetermined hydraulic pressure exceeding the operating hydraulic pressure.