JPH10159135A - Hydraulic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent jerking by reducing acceleration reaction force at the time of turning on a hydraulic transmission containing a revolving motor. SOLUTION: A pressure reducing valve device 107 is provided in the middle of a pressure line 40 to lead pressure from a pump discharge conduit 3 to an auxiliary control pressure chamber 6c to load pressure in the opening direction of a pressure compensating valve 6 for a revolving motor 106, a solenoid 108 to hold a valve element in a direction not to reduce pressure is provided on this pressure reducing valve device 107, this solenoid 108 is interlocked with a revolving position of a working front 104 of a hydraulic shovel 101, when it comes to be in the revolving position, the solenoid 108 is put off, and target compensating differential pressure of the pressure compensating valve 6 is lowered. The revolving position is detected by an angle sensor 115 to detect an angle of a boom 104a, a signal from this angle sensor 115 is input to a controller 116, and a command signal is output from the controller 116 to the solenoid 108.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive for a hydraulic shovel, and more particularly to a hydraulic drive for improving turning operability in a turning posture.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. Hei.
26587 and JP-A-4-306327.

[0003] In JP-A-7-26587,
The boom maximum raising angle and the maximum retraction angle of the arm in the turning posture of the hydraulic shovel are stored in the controller, and when each angle of the boom and the arm becomes the stored angle, the controller controls the turning motor. The stroke of the pilot switching valve is mechanically limited so that the turning angular velocity is limited.

In Japanese Patent Application Laid-Open No. 4-306327, the same is done by reducing the pilot pressure with a switching valve.

Japanese Patent Laid-Open Publication No. Sho 60-11706 discloses a load sensing control technique for controlling the capacity of a hydraulic pump so as to maintain a differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure of a plurality of actuators at a set value. There is a thing of the description.

In Japanese Patent Application Laid-Open No. Sho 60-11706, a variable displacement hydraulic pump, a plurality of actuators driven by hydraulic oil discharged from the hydraulic pump, and a plurality of actuators supplied from the hydraulic pump to the plurality of actuators are provided. A plurality of flow control valves for controlling the flow rate of pressure oil, a plurality of pressure compensating valves for controlling the same pressure difference before and after the plurality of flow control valves, a discharge pressure Ps of the hydraulic pump and a maximum load of the plurality of actuators Pressure difference ΔPLS from pressure PLSmax is set value ΔPLSr
and a pump displacement control device for controlling the displacement of the hydraulic pump so as to maintain the displacement at ef. The pressure compensating valves are respectively installed upstream of the flow control valve, and act on the differential pressure before and after the flow control valve in the valve closing direction, as well as the discharge pressure Ps of the hydraulic pump and the maximum load pressure PLSmax of the plurality of actuators.
And the differential pressure ΔPLS is applied in the valve opening direction.
Is controlled as the target differential pressure for the pressure compensation to control the differential pressure across the flow control valves to the same value.

[0007]

A small hydraulic excavator is often used for excavation work in a narrow place such as a small path in an urban area. In order to prevent the front attachment from colliding, take a so-called turning posture in which the boom is set to the maximum raising angle and the arm is set to the maximum retracting angle. Work in the posture is performed.

However, in the turning posture, the turning radius of the front becomes small, and the moment of inertia of the body including the upper revolving structure and the front becomes small. It is difficult to operate at low speed.

Further, the operator receives a reaction force (acceleration reaction force) of the angular acceleration generated in the upper swing body by driving the swing motor. This reaction force is inversely proportional to the moment of inertia of the upper swing body, and the moment of inertia is minimized in the turning posture, so that the reaction force is maximized. As a result, the operator is greatly shaken by the acceleration reaction force at the time of turning, a phenomenon called so-called jerking occurs, and the operability is reduced.

[0010] Japanese Patent Application Laid-Open No. 7-26587 and Japanese Patent Application Laid-Open
In Japanese Patent No. 306327, the maximum stroke (displacement) of a spool of a turning pilot switching valve for controlling a turning motor is disclosed.
, The turning angular velocity of the hydraulic shovel is limited, and the turning safety is improved. However, simply limiting the maximum stroke of the spool does not change the spool speed until the spool reaches the limited stroke end as compared to when the maximum stroke is not limited.
Therefore, when a normal lever operation is performed in the turning posture, the maximum value of the angular velocity of the turning motor is limited,
The angular acceleration will not change. As a result, the acceleration reaction force is not reduced, there is no effect on the jerk during turning, and the operability cannot be prevented from being reduced.

As a method of suppressing the acceleration reaction force at the time of turning as described above, in a hydraulic drive device described in Japanese Patent Application Laid-Open No. Sho 60-11706, one of a plurality of actuators is used.
One is a turning motor, and the compensation differential pressure of the pressure compensating valve of the flow control valve for supplying the pressurized oil to the turning motor is reduced, and the flow dividing ratio is set to be lower than other actuators.
However, in the hydraulic circuit configuration disclosed in Japanese Patent Application Laid-Open No. Sho 60-11706, it is impossible to individually set the compensation differential pressure of the pressure compensating valve, and the compensation differential pressure of the pressure compensating valve cannot be switched depending on the turning posture. .

Further, as a specific valve structure of the flow control valve and the pressure compensating valve, a set of the flow control valve and the pressure compensating valve is made into one section (unit device), and a multiple valve connecting these sections is provided. There is a control valve unit with a structure. In this control valve unit, a pressure line connected to a discharge pipe of a hydraulic pump is formed in a valve block, and pressure oil is supplied from this pressure line. However, if a device for changing the compensation differential pressure as described above is incorporated around the pressure compensating valve in such a multiple valve structure, the structure of the unit device itself becomes complicated, and it is structurally difficult to make the multiple valve structure. Become.

[0013] A first object of the present invention is to provide a hydraulic drive device capable of reducing the acceleration reaction force during turning and preventing jerk.

A second object of the present invention is to provide a control valve unit having a multiple valve structure using a set of a flow control valve and a pressure compensating valve as a unit, without complicating the unit, and achieving a target compensation difference. An object of the present invention is to provide a hydraulic drive device incorporating a device for changing pressure.

[0015]

[Means for Solving the Problems]

(1) In order to achieve the first object, the present invention provides a hydraulic pump, a plurality of actuators driven by hydraulic oil discharged from the hydraulic pump, and a supply from the hydraulic pump to the plurality of actuators. A plurality of flow control valves for controlling the flow rate of the pressure oil to be supplied, and a plurality of pressure compensating valves for controlling the differential pressure across the plurality of flow control valves to a target compensation differential pressure. A front actuator that drives the work front of the shovel,
In a hydraulic drive device having a turning motor for driving an upper turning body, a posture detecting means for detecting a posture of the work front, and a detection value of the posture detecting means are inputted, and when the work front becomes a turning posture, the turning is performed. Setting change means for setting the target compensation differential pressure of the pressure compensation valve of the flow control valve relating to the motor to be smaller than the target compensation differential pressure of the pressure compensation valves of the other flow control valves.

In the present invention configured as described above,
When the attitude detecting means detects the attitude of the work front and the attitude becomes the turning attitude, the setting change means sets the target compensation differential pressure of the pressure compensating valve of the flow control valve related to the turning motor to the pressure compensation of the other flow control valve. The target differential pressure difference of the valve is made smaller than that of the other flow control valves.

Here, since the flow rate of the pressure oil passing through the flow control valve depends on the pressure difference between the front and rear and the opening degree, if the pressure difference between the front and rear of the flow control valve decreases, only a limited flow rate can be obtained even with the same opening degree. Absent. That is, since the opening of the flow control valve corresponds to the stroke of the operating lever, the turning speed of the operating lever relative to the lever stroke is limited, and the effective stroke range of the operating lever does not change. The rate decreases, and the rate of change of the turning speed, that is, the turning acceleration, decreases. Therefore, even when the lever is operated at the normal lever operation speed, the acceleration reaction force at the time of turning becomes small, and the occurrence of jerk is suppressed.

(2) In the above (1), preferably,
The plurality of pressure compensating valves each include a first control pressure chamber that loads an upstream pressure of the flow control valve in a closing direction, a second control pressure chamber that loads a downstream pressure of the flow control valve in an opening direction, and an opening direction. A first auxiliary control pressure chamber for loading the discharge pressure of the hydraulic pump, and a second auxiliary control pressure chamber for loading the maximum load pressure of the plurality of actuators in the closing direction. A pressure reducing valve device installed in a pipe connecting a discharge pipe of the pump and a first auxiliary control pressure chamber of a pressure compensating valve related to the swing motor.

By providing the pressure compensating valve and providing the pressure reducing valve device in this manner, in the pressure compensating valve, the pump discharge pressure applied to the first auxiliary control pressure chamber and the pump discharge pressure applied to the second auxiliary control pressure chamber are set. Pressure difference, ie ΔP
By controlling the differential pressure across the flow control valve using the LS as the target compensation differential pressure and operating the pressure reducing valve device when the work front is in the turning position, the first pressure compensating valve related to the turning motor is operated. The pressure in the auxiliary pressure chamber falls below the pump discharge pressure, reducing the target compensation differential pressure. This allows
As described in the above (1), the turning acceleration is reduced, and even when the lever is operated at the normal lever operation speed, the acceleration reaction force during turning is reduced, and the occurrence of jerk is suppressed.

(3) In the above (2), preferably, the pressure reducing valve device has a solenoid acting in a direction to hold a valve body at a position where the discharge pressure of the hydraulic pump is not reduced, and The changing means further includes means for turning off the solenoid when the work front is in the turning posture.

Thus, when the posture of the work front becomes the turning posture, the pressure reducing valve device is operated, and the target compensation differential pressure of the pressure compensating valve related to the turning motor is reduced as described in (2) above.

(4) In order to achieve the second object, according to the present invention, in the above (2), there are three or more actuators and the flow control valves, and these flow control valves are pressure-compensated. A control valve unit having a multiple valve structure with a set of a flow control valve and a pressure compensating valve as a unit, together with a valve, and a valve block of the control valve unit, which is connected to a discharge line of the hydraulic pump. Pressure line and a common signal line to which the maximum load pressure is led, a pressure signal is supplied to each unit from the common pressure line and the signal line, and a flow control valve and a pressure A unit of the compensating valve is arranged at one end of the common pressure line and signal line with respect to another unit, and the pressure reducing valve is further arranged outside the unit as an additional unit. To.

As described above, the unit of the flow control valve and the pressure compensating valve related to the swing motor is arranged at one end of the common pressure line and the signal line, and the pressure reducing valve is arranged further outside as an additional unit. As a result, the target compensation differential pressure can be changed with a reasonable structure without complicating the unit devices of the flow control valve and the pressure compensating valve related to the swing motor and without making significant changes to the existing control valve unit. Becomes possible.

(5) Further, in the above (1), preferably, the posture detecting means is an angle sensor for detecting an angle of a boom of the work front, and the setting changing means is such that the angle of the boom is a predetermined value or more. , It is determined that the work front is in the turning posture.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a hydraulic drive device 10 according to a first embodiment in which the present invention is applied to a system of a hydraulic excavator 101.
The hydraulic drive device 100 includes a variable displacement hydraulic pump 1, actuators 106 and 22 driven by pressure oil discharged from the hydraulic pump 1,
The hydraulic pump 1 includes flow control valves 8 and 18 for controlling the flow rate of pressure oil supplied to the actuators 106 and 22 from the hydraulic pump 1, and pressure compensating valves 6 and 16 for controlling a differential pressure between the flow control valves 8 and 18. ing.

The pressure oil discharged from the hydraulic pump 1 is supplied to the respective actuators 22 and 106 via the discharge line 3, the pressure compensating valves 6 and 16, and the flow control valves 8 and 18. The flow rate control valves 8, 18 switch the pump discharge line 3 side and the tank 2 side to the pressure ports of the actuators 22, 106 to supply and discharge the pressure oil, thereby controlling the operation speed and operation of the actuators 22, 106. Control the direction.

The pressure compensating valves 6 and 16 are of a front type installed upstream of the flow control valves 8 and 18, respectively.
The pressure compensating valve 6 has a pair of opposing control pressure chambers 6a, 6b and a pair of opposing auxiliary control pressure chambers 6c, 6d, and the control pressure chambers 6a, 6b are located upstream and downstream of the flow control valve 8 respectively. , And the differential pressure across the flow control valve 8 acts in the valve closing direction, and the auxiliary control pressure chambers 6c, 6d
The discharge pressure Ps of the hydraulic pump 1 and the actuator 106,
The pressure PLS on the high pressure side (hereinafter referred to as the maximum load pressure) PLS among the 22 load pressures is derived, and the differential pressure ΔPLS between the discharge pressure Ps of the hydraulic pump 1 and the maximum load pressure PLSmax is caused to act in the valve opening direction. Thus, the differential pressure across the flow control valve 8 is controlled using the differential pressure ΔPLS as the target compensation differential pressure. The pressure compensating valve 16 is similarly configured.

As described above, the pressure compensating valves 6 and 16 use the same differential pressure ΔPLS as the target differential pressure and the respective flow control valves 8 and 18
By controlling the differential pressure before and after the flow, the flow control valves 8, 18
Is uniformly controlled to the differential pressure ΔPLS, and as a result, the pressure oil discharged from the hydraulic pump 1 is divided by the ratio of the opening areas (openings) of the respective flow control valves 8 and 18.

The hydraulic pump 1 is a swash plate pump capable of adjusting the discharge amount (capacity) per rotation by changing the tilt angle of the swash plate 28. The tilt angle of the swash plate 28 is controlled by a servo piston. It is adjusted by the operation of 30. The servo piston 30 can be operated by supplying and discharging pressure oil, and the pressure in the servo piston 30 is controlled by a tilt control valve 32.

The tilt control valve 32 controls the discharge pressure Ps of the hydraulic pump 1 and the maximum load pressure PLSma of the actuators 106 and 22.
A load sensing control valve for controlling the pressure difference ΔPLS with respect to x to be maintained at the target pressure difference ΔPLSref.
LSref is set by the spring 32a. It also has a spool 32b and control pressure chambers 32c and 32d, and guides the pressure from the discharge line 3 (the discharge pressure Ps of the hydraulic pump 1) to the control pressure chamber 32c, and sets the maximum load pressure PLSmax of the actuators 106 and 22. It is guided to the control pressure chamber 32d and operates by their differential pressure ΔPLS.

That is, the tilt control valve 32 is connected to the discharge line 3
(The discharge pressure Ps of the hydraulic pump 1) is input as the original pressure, and when the differential pressure ΔPLS is lower than the target differential pressure ΔPLSref, the spool 32b is controlled by the control pressure chambers 32c and 32d.
Moves to the left in the figure to release the pressure in the servo piston 30 to the tank 2. For this reason, the servo piston 30 moves rightward in the figure, increasing the tilt angle of the swash plate 28, and increasing the discharge amount of the hydraulic pump 1. As a result, the discharge pressure Ps of the hydraulic pump 2 increases, and the differential pressure ΔPLS increases. Conversely, if the differential pressure ΔPLS is higher than the target differential pressure ΔPLSref,
The spool 32b moves rightward in the figure by the control pressure chambers 32c and 32d, and guides the discharge pressure Ps of the hydraulic pump 1 to the servo piston 30. For this reason, the servo piston 30 moves to the left in the figure, reducing the tilt angle of the swash plate 28 and reducing the discharge amount of the hydraulic pump 1. As a result, the discharge pressure Ps of the hydraulic pump 1 decreases, and the differential pressure ΔPLS decreases. As a result, the differential pressure ΔPLS is maintained at the target differential pressure ΔPLSref.

Since the pressure difference between the flow control valves 8 and 18 is controlled by the pressure compensating valves 6 and 16 so as to be the same pressure difference ΔPLS, the pressure difference ΔPLS is changed to the target pressure difference ΔPLSref as described above. Is maintained as a result, the differential pressure across the flow control valves 8 and 18 is maintained at the target differential pressure ΔPLSref.

The flow control valves 8, 18 are respectively
It has load ports 23 and 55 for taking out the load pressures thereof when the actuators 106 and 22 are driven, and the load pressures taken out from these load ports 23 and 55 are pressure-compensated as pressures on the upstream side of the flow control valves 8 and 18, respectively. Valve 6,1
6 given. The high pressure side of the load pressures taken out from these load ports 23 and 55 is the shuttle valve 37.
And this pressure is supplied to the pressure compensating valves 6 and 16 and the tilt control valve 32 as the maximum load pressure PLSmax.

The actuator 106 is an excavator 10
The actuator 22 is another actuator of the hydraulic excavator 101.

FIG. 2 shows the appearance of the excavator 101.
The hydraulic excavator 101 has a lower traveling structure 102 and an upper revolving structure 103, and a work front 104 provided at the front of the upper revolving structure 103 so as to be vertically rotatable. The work front 104 includes a boom 104a, an arm 104b, and It is composed of a bucket 104c. The upper revolving superstructure 103 is shown in FIG.
Can be turned on the lower traveling body 102 by a turning motor 106 shown in FIG.
The arm 104b and the bucket 104c are vertically rotatable by hydraulic cylinders 22a, 22b, 22c, respectively. The actuator 22 shown in FIG. 1 is representative of one of the hydraulic cylinders 22a, 22b, 22c.

Conventionally, the pressure compensating valves 6 and 16 are configured so that the differential pressures across the flow control valves 8 and 18 are all controlled equally, and the individual flow control valves 8 and 18 are controlled according to the load conditions of the actuators 22 and 106. Can not set different pressure difference before and after compensation.

On the other hand, in the present invention, as shown in FIG. 1, a pressure line 40 for guiding pressure from the pump discharge line 3 to an auxiliary control pressure chamber 6c for applying pressure in the opening direction of the pressure compensating valve 6. Provided with a pressure reducing valve device 107, and a pressure compensating valve 6
Can be adjusted.

The pressure reducing valve device 107 has a solenoid 10
8 and the solenoid 108 is connected to the excavator 101
By interlocking with the turning posture of the work front 104, the pressure reducing function of the pressure reducing valve device 107 can be switched between valid and invalid depending on the turning posture.

That is, an angle sensor 115 for detecting the angle of the boom 104a and a controller 116 for inputting a signal from the angle sensor 115 are provided, and a command signal is output from the controller 116 to the solenoid 108. When the boom angle θ is smaller than the set angle θ _{0 as} shown in FIG.
8 is turned ON (valid), and the pressure reducing valve device 107 is turned ON.
When the boom angle θ becomes equal to or larger than the set angle θ ₀ , the control signal is turned off (disabled) and the control calculation is performed so that the pressure reducing function of the pressure reducing valve device 107 is enabled. . Here, the boom angle θ is determined as the angle of the boom 104a with respect to the horizontal direction as shown in FIG.

The details of the pressure reducing valve device 107 will be described.

In FIG. 1, the pressure reducing valve device 107 is provided with a position A where the flow of the pressure oil in the pressure line 40 is not interrupted at all, a flow restrictor 107a for restricting the flow of the pressure oil in the pressure line 40, and a restriction 107b from the pressure line 40. And a position B for discharging a part of the pressure oil in the pressure line 40 to the tank 2 through the tank B. These two positions A and B are located at the spool 107c.
The switching is controlled by the solenoid 108 and the pressures applied to the three control pressure chambers 109, 110, 111 acting on the spool 107c. The control pressure chambers 109 and 110 are provided so as to apply pressure in the direction of switching to the position A, the control pressure chamber 111 is provided so as to apply pressure in the direction of switching to the position B, and the control pressure chamber 109 is provided in the control pressure chamber 109. The discharge pressure Ps of the hydraulic pump 1 is guided through the pressure line 112, the maximum load pressure PLSmax is guided through the pressure line 113 to the control pressure chamber 110, and the pressure is reduced through the pressure line 114 into the control pressure chamber 111. Pressure P downstream of valve device 107
1 is led.

When the solenoid 108 is not excited, the pressure receiving areas of the control pressure chambers 109, 110 and 111 are set to s.
Assuming that the movement of the spool 107c is stationary, the pressures Ps, PLSmax, and P1 guided to the control pressure chambers 109, 110, and 111 are balanced, so that the following three equations are used. The pressure is concerned.

S3 · P1 = s1 · PLSmax + s2 · Ps (1) P1 = (s1 / s3) · PLSmax + (s2 / s3) · Ps (2) The auxiliary control pressure chambers 6c and 6d of the pressure compensating valve 6 Is set by the following equation.

ΔPc = P 1 −PLSmax (3) Now, the control pressure chambers 109, 110, 1 of the pressure reducing valve device 107.
When the pressure receiving area ratio of the pressure compensating valve 11 is set as in the following equation (4), the target compensation differential pressure ΔPc of the pressure compensating valve 6 becomes as in equation (5).

S1 / s3 + s2 / s3 = 1 (4) ΔPc = (s2 / s3) · (Ps−PLSmax) (5) In the equation (4), s1 / s2 and s3 are s1 / s2 because s1, s2, and s3 are areas. s3 ≦ 1 and s2 / s3 ≦ 1. The target compensation differential pressure ΔPc of the pressure compensating valve 6 can be set to s2 / s3 times the target compensation differential pressure of the pressure compensating valve 16 of the other flow control valve 18 by the pressure reducing valve device 107 as in the equation (5). Will be possible.

Since the flow rate of the pressure oil passing through the flow control valves 8 and 18 depends on the pressure difference between the front and rear and the opening, if the pressure difference between the front and rear of the flow control valve is set to be low, the same degree of opening is restricted to some extent. Only the flow rate flows. By adjusting the areas s1, s2, and s3, the target compensation differential pressure of the pressure compensating valve 6 when the function of the pressure reducing valve device 107 is effective can be set freely lower than the other pressure compensating valves 16. Become.

FIG. 4 shows this relationship. The proportionality of the flow rate passing through the flow control valve 8 to the opening degree of the flow control valve 8 is maintained by the pressure compensating valve 6. In this case, the slope of the proportional straight line is determined depending on the target compensation differential pressure of the pressure compensation valve 6. When the target compensation differential pressure is set low by the pressure reducing valve device 107, the slope of the straight line becomes small, and the flow rate varies even with the same opening. That is, the maximum flow rate when the opening degree is maximized decreases from Qmax to Qmax '. Further, even if the slope of the proportional line becomes small, the range of the effective opening of the flow control valve does not change, and the range of the effective stroke of the operating lever (not shown) corresponding to the effective opening of the flow control valve does not change. The fine operability is improved.

When the solenoid 108 is excited, the spool 107c of the pressure reducing valve device 107 is moved to the control pressure chamber 10
Pressures Ps, PLSmax, P led to 9, 110, 111
Regardless of the balance between the two, it is forcibly fixed at the position A. The solenoid 108 enables the pressure reducing function of the valve device 107 to be enabled / disabled.

In the present embodiment configured as described above, as shown by the posture 2 in FIG. 5, when the work front 104 is set to a small turning posture in a narrow place where the work front 104 is folded, the boom angle θ with respect to the horizontal direction is large. Therefore, this is detected by the boom angle sensor 115 and the controller 116
The pressure reduction function of the pressure reducing valve device 107 is made effective by the control processing described above, and the target compensation differential pressure of the pressure compensating valve 6 is set lower.
Thereby, the opening degree of the flow control valve 8 of the swing motor 106,
In other words, the turning speed of the operating lever with respect to the lever stroke is limited, and the effective stroke range of the operating lever does not change, so that the turning speed can be finely adjusted and the fine operability is improved.

In the small turning posture of the posture 2, since the turning radius of the work front 104 is smaller than that of the posture 1, the moment of inertia of the upper revolving unit 103 becomes small, and the reaction of the turning torque becomes large. The turning torque is proportional to the turning angular acceleration generated at the time of turning, and the turning acceleration depends on the changing speed of the opening degree of the flow control valve 8.

In the present embodiment, even when the lever is operated at a normal lever operating speed, the inclination of the proportional line shown in FIG. 3 is small as described above, and the rate of change of the passing flow rate with respect to the opening is small. The rate is low. For this reason,
The recoil at the time of turning is small, and the occurrence of jerk can be suppressed.

In the above-described embodiment, when the controller 116 obtains the excitation signal of the solenoid 108 from the boom angle θ, the excitation signal is stepped before and after the set angle θ _0.
Although N · OFF is set, the control calculation in the controller 116 is not limited to this. For example, as shown in FIG. 6, the excitation signal may be set to be continuously reduced from a certain angle θ ₀₂ which is smaller than the set angle θ _{01 at} which the excitation signal is switched to OFF (invalid). In this case, it can be variable in accordance with the inclination of the proportional straight line as shown in boom angle theta in FIG. 7, a boom angle theta ₀₁
Even if the operation is performed as described above, the pressure reducing function of the pressure reducing valve device 107 is not rapidly switched, and it is possible to reduce the impact at the time of switching. Also, if the boom angle θ is θ ₀₁
The inclination of the proportional straight line corresponding to the boom angle (maximum flow rate and the flow rate change rate with respect to the opening) is set in the range of theta ₀₂ and, fine-grained pivot in response to the boom angle at a small turning attitude (moment of inertia) The torque can be controlled, and the occurrence of jerk can be more effectively suppressed.

A second embodiment of the present invention will be described with reference to FIGS. In the drawing, members equivalent to those shown in FIG. 1 are denoted by the same reference numerals. This embodiment shows an actual circuit configuration and valve structure when there are three or more actuators and flow control valves.

In FIG. 8, a hydraulic drive device 100A of the present embodiment includes a plurality of actuators 106, 22a to 22a.
d, the actuator 106 is a turning motor as in the first embodiment, and the actuators 22a to 22c
Are the boom cylinder, arm cylinder, and bucket cylinder shown in FIG. 2, and are hydraulic cylinders (not shown) for driving the actuator 22d, for example, the blade 102a shown in FIG.

The actuators 106 and 22
A control valve unit 119 provided with flow control valves 8, 18a to 18d and pressure compensating valves 6, 16a to 16d is provided for a to 22d. This control valve unit 119
Are flow control valves 8, 18a to 18d and pressure compensating valves 6,
A set of flow control valves and pressure compensating valves of each of 16a to 16d is made into one section (unit device), and these sections are connected in a multiple valve structure, and a flow control valve 8 and a pressure as shown in FIG. Section 120 of compensating valve 6, section 120a of flow control valve 18a and pressure compensating valve 16a similar to section 120, section 120b of flow control valve 18b and pressure compensating valve 16b, and flow control valve 18
c and a section 120c of the pressure compensating valve 16c, and a flow control valve 18d and a section 120d of the pressure compensating valve 16d. A pressure reducing valve device 10 as shown in FIG.
Only seven sections 121 are provided.

FIG. 11 shows sections 120, 120a-1.
20 shows an arrangement relationship between 20d and section 121. FIG.
Section 12 of the pressure reducing valve device 107 as a comparative example.
It shows a similar arrangement relationship when there is no 1.

In FIG. 11, the main body block 119a of the control valve unit 119 includes a discharge line 4 of the hydraulic pump 1.
, A common signal line 38 for supplying the extracted maximum load pressure PLSmax, a signal line 36a-36c for connecting the shuttle valves 37, 37a-37c for extracting the maximum load pressure PLSmax, and a common signal line 38 for supplying the extracted maximum load pressure PLSmax. , A common tank line 2a leading to the tank 2 is formed,
These lines penetrate substantially the entire length of the main body block 119a in a direction perpendicular to the spools of the flow control valves 8, 18a to 18d, and are associated with the flow control valves 8, 18a to 18d and the pressure compensating valves 6, 16a to 16d. It is connected to the site.

Here, in the configuration of FIG. 12 where there is no section of the pressure reducing valve device 107, the sections 120, 12
The pump discharge pressure Ps is led by a common pressure line 4a to the auxiliary control pressure chamber for setting the target compensation differential pressure of the pressure compensation valves 16a to 16d of 0a to 120d, and the maximum load is sent by a common signal line 38. The pressure PLSmax is derived. This is illustrated in FIG. 1 showing the control valve unit of the present invention.
The configuration of FIG. 1 is basically the same except for the point described later, and the pressures Ps, P
By supplying LSmax, the internal structure of the control valve unit can be simplified.

Further, as shown in FIG.
There are a feeder passage 7, a load check valve 9, actuator lines 10, 11 and the like around the zero pressure compensating valve 6, and it is very difficult to incorporate the pressure reducing valve device 107 in the section 120 in terms of space.

Therefore, in the present invention, a section 121 including only the pressure reducing valve device 107 as shown in FIG. 10 is provided.
Further, as shown in FIG. 11, a section 120 for the swing motor 106 is disposed at one end of the pressure line 4a and the signal line 38 common to the other sections 120a to 120d, and further outside the pressure reducing valve device 107. The section 121 is added so that only the target compensation differential pressure for the turning operation can be changed corresponding to the turning posture without changing the target compensation differential pressure set for the other pressure compensating valves 16a to 16d. In this case, the pressure line 4a for supplying the pump discharge pressure to the other pressure compensating valves 16a to 16d is closed by the plug 122 before the section 120 relating to the swing motor, and the auxiliary control pressure chamber 6c of the pressure compensating valve 6 has a pressure reducing valve device. The control pressure P1 is supplied from the section 121 of 107 by the pressure line 40a.

As described above, the section 120 for changing the target compensation differential pressure of the pressure compensation valve 16 is connected to the common pressure line 4a.
By disposing it at one end of the signal line 38 and further adding a section 121 of the pressure reducing valve device 107 to the outside thereof, the target compensation differential pressure of the pressure compensating valve 16 can be reduced without complicating the internal structure of the section 120. Can be changed. Also, when the section 121 of the pressure reducing valve device 107 is added to an existing control valve unit, no major structural change is required.

The above are the embodiments of the present invention, and these can be variously modified within the spirit of the present invention. For example, in the above embodiment, the pressure compensating valve has a configuration having two auxiliary control pressure chambers, and the change of the target compensation differential pressure of the pressure compensating valve is performed purely hydraulically. However, one auxiliary control pressure chamber is provided. Electrical control may be incorporated by introducing a hydraulic signal corresponding to the pump discharge pressure and the differential pressure to the auxiliary control pressure chamber, and reducing the hydraulic signal by an electromagnetic proportional pressure reducing valve.

[0064]

According to the present invention, the acceleration reaction force during turning can be reduced, jerk can be prevented, and turning fine operability can be improved.

Further, according to the present invention, a rational structure can be achieved without complicating the unit devices of the flow control valve and the pressure compensating valve related to the swing motor, and without making significant changes to the existing control valve unit. Thus, the target compensation differential pressure can be changed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a hydraulic drive device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an appearance of a hydraulic excavator.

FIG. 3 is a functional block diagram showing processing contents of a controller.

FIG. 4 is a diagram showing the relationship between the valve opening and the flow rate of the flow control valve when the target compensation differential pressure of the pressure compensation valve is set smaller by the pressure reducing valve device.

FIG. 5 is a posture 1 in which a work front of the excavator is extended.
FIG. 5 is a diagram showing a turning posture 2 in which the work front is folded.

FIG. 6 is a functional block diagram showing another processing content of the controller.

FIG. 7 is a diagram showing the relationship between the valve opening and the flow rate of the flow control valve when the target compensation differential pressure of the pressure compensation valve is set smaller by the pressure reducing valve device.

FIG. 8 is a circuit diagram showing a hydraulic drive device according to a second embodiment of the present invention.

FIG. 9 shows a section for the swing motor of the control valve unit.

FIG. 10 shows a section of the pressure reducing valve device of the control valve unit.

FIG. 11 is a diagram showing an arrangement relationship of each section of the control valve unit.

FIG. 12 is a diagram showing an arrangement relationship of each section of the control valve unit when there is no section of the pressure reducing valve device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable displacement hydraulic pump 6, 16 Pressure compensating valve 6a, 6b Control pressure chamber 6c, 6d Auxiliary control pressure chamber 8, 18 Flow control valve 100 Hydraulic drive device 101 Hydraulic excavator 102 Lower traveling body 103 Upper revolving body 104 Work front 106 Swing motor 107 Pressure reducing device 108 Solenoid 109-111 Control pressure chamber 115 Angle sensor 116 Controller 119 Control valve unit 121 Section of control valve device (unit)

Claims (5)

[Claims] 1. A hydraulic pump, a plurality of actuators driven by pressure oil discharged from the hydraulic pump, and a plurality of flow rate controls for controlling a flow rate of pressure oil supplied from the hydraulic pump to the plurality of actuators. A valve, and a plurality of pressure compensating valves for controlling a differential pressure across the plurality of flow control valves to a target compensation differential pressure, wherein the plurality of actuators include a front actuator for driving a work front of a hydraulic shovel; In a hydraulic drive device having a turning motor for driving a body, a posture detecting means for detecting a posture of the work front, and a detection value of the posture detecting means is input, and when the work front is in a turning posture, the turning motor Setting change procedure for setting the target compensation differential pressure of the pressure compensating valve of the flow control valve concerned to be smaller than the target compensation differential pressure of the pressure compensating valves of the other flow control valves Hydraulic drive system, characterized in that it comprises and. 2. The hydraulic drive device according to claim 1, wherein each of the plurality of pressure compensating valves has a first control pressure chamber for applying an upstream pressure of the flow control valve in a closing direction, and a flow control valve in an opening direction. A second control pressure chamber for applying the downstream pressure of the hydraulic pump, a first auxiliary control pressure chamber for applying the discharge pressure of the hydraulic pump in the opening direction, and a second auxiliary pressure chamber for applying the maximum load pressure of the plurality of actuators in the closing direction. A control pressure chamber, wherein the setting change means includes a pressure reducing valve device installed in a pipe connecting the discharge pipe of the hydraulic pump and a first auxiliary control pressure chamber of a pressure compensating valve related to the swing motor. A hydraulic drive device characterized by the above-mentioned. 3. The hydraulic drive device according to claim 2, wherein the pressure reducing valve device has a solenoid acting in a direction for holding the valve body at a position where the discharge pressure of the hydraulic pump is not reduced, and the setting change means. The hydraulic drive device further comprises means for turning off the solenoid when the work front is turned. 4. The hydraulic drive according to claim 2, wherein
There are three or more of the actuator and the flow control valve, and the flow control valve is constituted by a control valve unit having a multi-valve structure in which a set of the flow control valve and the pressure compensating valve is a unit device together with the pressure compensating valve. In addition, a common pressure line connected to the discharge line of the hydraulic pump and a common signal line through which the maximum load pressure is led are formed in the valve block of the control valve unit, and each unit is formed from the common pressure line and the signal line. The apparatus is configured to supply a pressure signal to the apparatus, and a unit device of the flow control valve and the pressure compensating valve related to the swing motor is arranged at one end of the common pressure line and the signal line with respect to another unit device, A hydraulic drive device characterized in that a pressure reducing valve device is further arranged outside as an additional unit device. 5. The hydraulic drive device according to claim 1, wherein
The posture detecting means is an angle sensor for detecting an angle of a boom of the work front, and the setting change means determines that the work front is in a turning posture when the angle of the boom becomes a predetermined value or more. Hydraulic drive.