JP2656154B2 - Hydraulic control device for construction machinery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic control device for a construction machine, and more particularly to a hydraulic control device for a construction machine having a plurality of actuators such as a hydraulic shovel.

BACKGROUND ART A hydraulic control device of a construction machine such as a hydraulic shovel includes a hydraulic pump, a plurality of actuators driven by hydraulic oil supplied from the hydraulic pump, and a hydraulic oil supplied to the plurality of actuators from the hydraulic pump. A plurality of valve devices for controlling the flow rate. As this type of hydraulic control device, a load sensing system that controls the discharge pressure of a hydraulic pump in response to a load pressure is known.
One example is WO90 / 00683. This prior art includes pump control means for controlling the displacement of a hydraulic pump so that the discharge pressure of the hydraulic pump becomes higher than the maximum load pressure of the plurality of actuators by a predetermined value. And a pressure compensating valve (auxiliary valve) that is arranged in series upstream of the variable throttle and controls a differential pressure across the variable throttle. ). By controlling the differential pressure across the variable throttle with the pressure compensating valve, it is possible to reliably supply pressure oil to the actuator on the low load side and simultaneously drive multiple actuators during multiple operations that drive multiple actuators. It becomes possible.

Further, the prior art described in WO90 / 00683 includes a sensor that detects a differential pressure between a pump discharge pressure and a maximum load pressure (hereinafter, appropriately referred to as “LS differential pressure”) and outputs a corresponding differential pressure signal,
Means for storing, for each actuator, an output pattern of a pressure compensating valve control amount for the differential pressure signal, and calculating a corresponding control amount on the output pattern in accordance with the differential pressure signal from the sensor; , The pressure compensating valves are individually controlled. By controlling the pressure compensating valve in this way, the supply flow rate is additionally controlled by the pressure compensating valve in addition to the control of the supply flow rate by the variable throttle, and the plurality of actuators are simultaneously driven by the auxiliary flow rate control. In the combined operation, it is possible to reliably supply the pressure oil to the actuator on the low load side even in the saturation state where the discharge flow rate of the hydraulic pump is insufficient, and to give the optimal split ratio according to the type of actuator , Improving operability.

FIGS. 15 and 16 of WO90 / 00683 show that the operating signal output from the turning and boom operating lever device is electrically detected, and a plurality of pressure compensating valve control amounts with respect to the differential pressure signal described above are detected. The output pattern is stored in association with the detected operation signal, and when the operation signal is output from the operation lever device, an output pattern corresponding to the operation signal is selected, and a differential pressure signal is displayed on the selected output pattern. Is calculated. By calculating the control amount of the pressure compensating valve in accordance with the operation signal in this way, the auxiliary flow control by the pressure compensating valve according to the operation pattern of the actuator becomes possible, and the operability is further improved.

However, the prior art described in WO90 / 00683 has the following problems.

As described above, in the related art, the output pattern of the pressure compensating valve control amount with respect to the differential pressure signal is stored, and the corresponding control amount is calculated on the output pattern according to the differential pressure signal from the sensor. Here, the relationship between the differential pressure signal and the control amount is generally set so that the control force acting on the pressure compensating valve in the closing direction increases as the LS differential pressure decreases. This is to prevent the saturation of the pump. That is, the discharge flow rate of the hydraulic pump is insufficient,
When the LS differential pressure decreases, the control force in the closing direction of the pressure compensating valve is increased, and the opening degree of the pressure compensating valve is reduced to maintain an appropriate shunt ratio. However, setting the relationship between the differential pressure signal and the control amount in this way is, of course, every time the differential pressure signal changes, the calculated control amount also changes, and the pressure compensating valve responds accordingly. It will be controlled in the closing direction or the opening direction.

By the way, in load sensing control of a construction machine such as a hydraulic shovel, the LS differential pressure, that is, the differential pressure between the pump discharge pressure and the maximum load pressure changes depending on causes other than the saturation of the hydraulic pump. For example, when the load on the actuator fluctuates and when the input amount of the operation lever device is changed, the pump discharge flow rate matches the target flow rate and the LS differential pressure matches the target value by load sensing control. The LS differential pressure changes during a transitional period until the pressure changes. Also,
As shown in FIGS. 15 and 16 of WO 90/00683, a plurality of output patterns of the pressure compensating valve control amount are stored in association with the operation signal, and the control amount of the pressure compensating valve is calculated in accordance with the operation signal. In this case, the operation pattern of the actuator is switched, and when the output pattern changes, the LS differential pressure also changes transiently.

Thus, in load sensing control,
Each time the LS differential pressure changes, the pressure compensating valve is controlled in the closing direction or the opening direction as described above. The operation of the pressure compensating valve naturally changes the flow rate of the pressure oil supplied to the actuator, and in some cases, causes an unexpected sudden change in the actuator operating speed, thereby affecting the operability. In particular, when the output patterns are associated with a large number of operation signals in the prior art described in FIGS. 15 and 16 of WO90 / 00683, the frequency of switching the output patterns by switching the operation patterns also increases. Therefore, the frequency of the change in the LS differential pressure also increases, which may significantly impair operability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic control device that performs load sensing control that can appropriately control the flow rate of pressure oil supplied to an actuator when the LS differential pressure changes and realize excellent operability. It is to provide a hydraulic control device for a machine.

DISCLOSURE OF THE INVENTION In order to achieve the above object, according to the present invention, a variable displacement hydraulic pump, a plurality of actuators driven by pressurized oil supplied from the hydraulic pump, and a hydraulic pump between the hydraulic pump and the actuator A plurality of valve means connected to the hydraulic pump, and pump control means for controlling a displacement of the hydraulic pump so that a discharge pressure of the hydraulic pump is higher than a maximum load pressure of the plurality of actuators by a predetermined value. Each of the valve means changes an opening degree in accordance with an operation signal from the operation means, and controls a flow rate of pressure oil supplied to a corresponding actuator; A hydraulic pressure control device for a construction machine having an auxiliary valve for auxiliary control of the flow rate of hydraulic oil supplied to the hydraulic pump. First detecting means for detecting a differential pressure between a force and the maximum load pressure and outputting a corresponding differential pressure signal; and (B) detecting operation patterns of the plurality of actuators and outputting a corresponding operation pattern signal. Second detecting means, (C)
Valve control means for calculating a valve control signal based on the differential pressure signal and the operation pattern signal output from the first and second detection means, and controlling the driving of the auxiliary valve. (A) storing a plurality of output patterns of the auxiliary valve control amount as a function of the differential pressure signal in association with the operation pattern signal, and when the operation pattern signal is output from the second detection means, A first means for selecting an output pattern corresponding to the pattern signal and calculating an auxiliary valve control amount corresponding to the differential pressure signal output from the first detecting means on the output pattern; The change speeds of a plurality of sets of the valve control amounts are stored in association with the operation pattern signals, and when the operation pattern signals are output from the second detection means, the change speeds of the sets corresponding to the operation pattern signals are calculated. Selection Second means for; (c) the first
A third means for calculating the valve control signal by combining the auxiliary valve control amount calculated by the means and the change speed of the set selected by the second means. Is provided.

In the present invention configured as described above, when the operating means is operated and the corresponding actuator (single or plural) is driven, the second detecting means outputs a corresponding operation pattern signal, and this operation pattern signal Is input to the valve control means together with the differential pressure signal output from the first detection means. In the valve control means, first, an output pattern of the auxiliary valve control amount corresponding to the operation pattern signal is selected by the first means, and the auxiliary valve control amount corresponding to the differential pressure signal is calculated on this output pattern. Therefore, by setting the output pattern to a pattern that is considered to be optimal for each operation pattern, an optimum shunt ratio can be given to the composite operation such as securing independence of the operation between the actuators in the composite operation, and the operability can be improved. .

In the valve control means, together with the calculation of the output pattern, the second means selects a set control rate change speed corresponding to the operation pattern at that time, and the third means selects the control rate change speed and the above-described change speed. The valve control signal is calculated by combining the control amount obtained from the output pattern. Therefore, by setting the control amount change speed so that the auxiliary valve operates at a response speed that is optimal for the operation pattern at that time with respect to the change in the differential pressure signal, the auxiliary valve when the differential pressure signal changes is set. An excellent control that appropriately controls the dynamic response and thereby appropriately controls the flow rate of the pressure oil supplied to the actuator when the differential pressure signal changes, without causing an unexpected sudden change in the actuator operating speed. Operability can be realized.

In the hydraulic control device, preferably, the first means includes: (1) means for storing a reference pattern of the auxiliary valve control amount as a function of the differential pressure signal; and (2) a plurality of sets for the reference pattern. Means for storing variable data in association with the operation pattern signal, and when the operation pattern signal is output from the second detection means, selecting a set of variable data corresponding to the operation pattern signal;
(3) means for obtaining the output pattern by combining the reference pattern and the selected set of variable data, and calculating an auxiliary valve control amount corresponding to the differential pressure signal on the output pattern.

By determining an output pattern using a combination of one reference pattern and its variable data as described above, it is possible to store the same number of output patterns with a smaller storage capacity as compared with a case where many output patterns are directly stored. Can,
The valve control means can be manufactured at low cost.

Preferably, the plurality of sets of variable data for the reference pattern are a gain for changing the inclination of the reference pattern, an offset for translating the reference pattern, a maximum value limiter for limiting the maximum value of the reference pattern, and a minimum value for the reference pattern. Includes each value of the minimum limiter.

In the hydraulic control device, preferably, the plurality of sets of change speeds stored by the second means include respective values of a change speed in a closing direction and a change speed in an opening direction of the auxiliary valve.

Preferably, the third means determines whether the auxiliary valve control amount calculated by the first means is a value for operating the auxiliary valve in a closing direction or an opening direction, and according to a result of the determination. One of the changing speed in the closing direction and the changing speed in the opening direction is selected, and the valve control signal is calculated by combining the selected changing speed with the auxiliary valve control amount calculated by the first means.

Preferably, the second detection means includes an operation signal detection means for detecting an operation signal output from each of the operation means and outputting a corresponding operation mode signal.

According to the present invention, to achieve the above object, a variable displacement hydraulic pump, a plurality of actuators driven by pressure oil supplied from the hydraulic pump, and between the hydraulic pump and the actuator A plurality of valve means connected thereto, and a pump control means for controlling a displacement of the hydraulic pump so that a discharge pressure of the hydraulic pump is higher than a maximum load pressure of the plurality of actuators by a predetermined value. A valve, each of which changes an opening degree in response to an operation signal from the operation unit and controls a flow rate of pressure oil supplied to a corresponding actuator; A hydraulic pressure control device for a construction machine having an auxiliary valve for auxiliary control of the flow rate of hydraulic oil supplied to the hydraulic pump. And the detected differential pressure of the maximum load pressure, a first detecting means for outputting a corresponding differential pressure signal;
(B) second detecting means for detecting an operation pattern of the plurality of actuators and outputting a corresponding operation pattern signal, wherein the pump control means comprises: (a) a control gain of a plurality of sets of the hydraulic pump; (B) in association with the operation pattern signal, and when the operation pattern signal is output from the second detection means, first means for selecting a set of control gains corresponding to the operation pattern signal; A) calculating a deviation between the differential pressure signal output from the first detecting means and a preset target differential pressure, and calculating the difference by using the differential pressure deviation and a set of control gains selected by the first means; A second means for calculating a pump control signal for reducing the pressure deviation, and controlling the displacement of the hydraulic pump based on the pump control signal. It is.

In the present invention configured as described above, when the operating means is operated and the corresponding actuator (single or plural) is driven, the second detecting means outputs a corresponding operation pattern signal, and this operation pattern signal Is input to the pump control means together with the differential pressure signal output from the first detection means. In the pump control means, a set of control gains corresponding to the operation pattern signal is selected by the first means, and a differential pressure deviation between the differential pressure signal and a preset target differential pressure and its control gain are selected by the second means. Using the data, a pump control signal for reducing the differential pressure deviation is calculated. Therefore, by setting the control gain so that the swash plate tilt of the hydraulic pump changes at a response speed optimal for the operation pattern at that time with respect to the change in the differential pressure signal, the change in the differential pressure signal Appropriately controls the response speed of the swash plate tilt, thereby properly controlling the flow rate of the pressure oil supplied to the actuator when the differential pressure signal changes, without causing an unexpected sudden change in the actuator operation speed. Excellent operability can be realized.

Preferably, the plurality of sets of control gains stored by the first means are respectively a value of an increase gain suitable for controlling the displacement of the hydraulic pump in an increasing direction and a value of a decreasing gain suitable for controlling the displacement in a decreasing direction. including.

Preferably, the second means determines whether the differential pressure deviation is a value for controlling the displacement of the hydraulic pump in an increasing direction or a decreasing direction, and according to the determination result, One of the increase gain and the decrease gain is selected, and the pump control signal is calculated using the selected gain and the differential pressure deviation.

More preferably, the pump control signal stores: (f) a plurality of target differential pressures between the discharge pressure of the hydraulic pump and the maximum load pressure in association with the operation pattern signal; And third means for selecting a target differential pressure corresponding to the operation pattern signal when the operation pattern signal is output, wherein the second means is configured to output the target differential pressure selected by the third means. The pressure is used as the preset target differential pressure. In this case, the pump control means
Along with the calculation of the control gain, the third means selects a target differential pressure corresponding to the operation pattern at that time, and the second means uses the target differential pressure as the preset target differential pressure. , A pump control signal for reducing the differential pressure deviation is calculated. Therefore, by setting the target differential pressure so as to obtain the optimum flow rate characteristics for the operation pattern at that time, the response of flow rate changes can be ensured, such as when the operation pattern is switched, pressure oil can be supplied to the high-load-side actuator without fail. And excellent operability can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing one-third of the entire configuration of a hydraulic control device for a construction machine according to an embodiment of the present invention.

FIG. 2 is a schematic view showing another third of the hydraulic control device shown in FIG.

FIG. 3 is a schematic diagram showing the remaining 1/3 of the hydraulic control device shown in FIGS. 1 and 2.

FIG. 4 is a schematic diagram of the pump control device shown in FIG.

FIG. 5 is a block diagram showing a pump control signal calculation function and a valve control signal calculation function provided in the controller shown in FIG.

FIG. 6 is a diagram showing details of data stored in the pump control gain calculation block shown in FIG.

FIG. 7 is a diagram showing details of data stored in the target differential pressure calculation block shown in FIG.

FIG. 8 is a diagram showing details of data stored in the control pressure variable calculation block shown in FIG.

FIG. 9 is a diagram showing a reference line of the compensation pressure with respect to the input differential pressure.

FIG. 10 is a diagram showing a reference line serving as a reference pattern of the control pressure with respect to the input differential pressure.

FIG. 11 is a diagram showing a change in characteristics due to a gain of the variable data stored in the control pressure variable calculation block.

FIG. 12 is a diagram showing a change in characteristics due to an offset in the variable data stored in the control pressure variable calculation block.

FIG. 13 is a diagram showing a change in characteristics of the variable data stored in the control pressure variable calculation block by the MAX limiter.

FIG. 14 is a diagram showing a change in characteristics of the variable data stored in the control pressure variable calculation block by the MIN limiter.

FIG. 15 is a diagram showing an output pattern obtained as a result of superimposing changes in each characteristic by a gain, an offset, a MAX limiter, and a MIN limiter.

FIG. 16 is a diagram showing details of data stored in the control pressure change speed calculation block shown in FIG.

FIG. 17 is a diagram showing the configuration of the pump control unit shown in FIG.

FIG. 18 is a diagram showing the configuration of the valve control unit shown in FIG.

FIG. 19 is a side view of a hydraulic shovel on which the hydraulic control device shown in FIGS. 1 to 3 is mounted.

 FIG. 20 is a top view of the excavator.

FIG. 21 is a diagram showing an output pattern of the control pressure with respect to the input differential pressure when the operation pattern is traveling alone.

FIGS. 22 (A) and (B) are diagrams showing an output pattern of the control pressure with respect to the input differential pressure when the operation pattern is a plurality of traveling.

FIG. 23 is a diagram showing an output pattern of the control pressure with respect to the input differential pressure when the operation pattern is the turning alone.

FIGS. 24 (A) and (B) are diagrams showing output patterns of the control pressure with respect to the input differential pressure when the operation pattern is boom raising and arm pulling.

FIG. 25 is a diagram showing an output pattern of the control pressure with respect to the input differential pressure when the operation pattern is the boom raising alone.

FIGS. 26 (A) and (B) are diagrams showing output patterns of the control pressure with respect to the input differential pressure when the operation pattern is a combined operation including turning and arm pulling.

27 to 29 are diagrams showing another embodiment of the operation signal detecting means.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a hydraulic control device for a construction machine according to an embodiment of the present invention will be described with reference to the drawings.

1 to 3 show a hydraulic control device when the present invention is applied to a hydraulic shovel. In these figures, the hydraulic control device of the present embodiment includes one variable displacement hydraulic pump driven by a prime mover 250, that is, a main pump 20.
0, and a plurality of actuators driven by pressure oil discharged from the main pump 200, namely, a swing motor 201, a boom cylinder 202, an arm cylinder 251, a bucket cylinder 252, a left traveling motor 271 and a right traveling motor 272, A flow control valve for controlling the flow of pressure oil supplied to each of the plurality of actuators, that is, a turning direction switching valve 203 incorporating a variable throttle, a boom direction switching valve 204, an arm direction switching valve 253, and a bucket direction. The switching valve 254, the left traveling direction switching valve 273, and the right traveling direction switching valve 274, which are included in these direction switching valves in the actual structure, are arranged in series upstream thereof corresponding to the respective variable throttles, and are variable. A pressure compensating valve 205, 206, 255, 256, 275, 276 as an auxiliary valve for controlling the flow rate of the pressure oil supplied to the actuator. That.

The discharge line 207 of the main pump 200 is a supply line 207A, 207B, 207C.
Are connected to the pressure compensating valves 205, 206, 255, 256, 275, and 276, and a relief valve and an unload valve (not shown) are connected to the discharge pipeline 207. By the relief valve, when the pressure oil from the main pump 200 reaches the set pressure of the relief valve, it flows out to the tank 208, and the discharge pressure of the main pump 200, that is, the pump pressure is prevented from becoming higher than the set pressure. By the unload valve, when the pressure oil from the main pump 200 reaches a pressure obtained by adding the set pressure of the unload valve to the maximum load pressure PLmax of the actuators 201, 202, 251, 252, 271 and 272, it flows out to the tank 208, and is prevented from exceeding the pressure. You.

The discharge amount of the main pump 200 is controlled by the pump control device 209.
The pump pressure Ps is controlled to be higher than the maximum load pressure PLmax by a predetermined value ΔPLsr, and load sensing control is performed.

The directional control valves 203, 204, 253, 253, 273, 274 are hydraulic pilot type valves respectively operated by operating means, for example, pilot valves 210, 211, 260, 261, 280, 281.The pilot valves 210, 211, 260, 261, 280, 281 are each operated lever 2
Pilot pressure a1 or a2, pilot pressure b1 or b2, pilot pressure c1 or c2, pilot pressure d1 or d2, pilot pressure e1 or e2 and pilot pressure f1 or f2 by manual operation of 10a, 211a, 260a, 261a, 280a, 281a Is generated, and these pilot pressures are applied to the directional control valves 203, 204, 253, 253, 273, 274, and the variable throttles of the directional control valves are opened to corresponding opening degrees.

The drive units 205a, 205 which guide the pressure compensating valves 205, 206, 255, 256, 275, 276 with the outlet pressure and the inlet pressure of the variable throttles of the direction switching valves 203, 204, 253, 253, 273, 274, respectively, and apply the first control force based on the differential pressure across the variable throttles in the valve closing direction.
b; 206a, 206b; 255a, 255b; 256a, 256b; 275a, 275b and 276a,
276b, springs 212, 213, 262, 263, 282 and 283, and drive units 205c, 206c, 255c, 256c, 275c and 27 to which the control pressure output from the electromagnetic proportional pressure reducing valves 216, 217, 266, 267, 286 and 287 via the pilot lines 214, 215, 264, 265, 284 and 285 are guided.
6c, the springs 212, 213, 262, 263, 282 and 283 and the drive
The second control force in the valve opening direction is applied by 205c, 206c, 255c, 256c, 275c and 276c, and the target value of the differential pressure across the corresponding variable throttle is set.

Pump control device 209, pilot valve 210, 211, 260, 261-2
80,281 and proportional pressure reducing valves 216,217,266,267,286 and 287
There is a common pilot pump 220 to pilot line 221
The pilot pressure is supplied via. Directional valve 203,
204, the direction switching valves 253, 253 and the direction switching valves 273, 274,
Selection means for deriving the maximum load pressure PLmax of the actuators 201, 202, 251, 252, 271, 272, that is, the shuttle valves 222A, 222B, 222C, and the detection pipe 222 are respectively connected.

Further, the hydraulic control device of the present embodiment includes a displacement sensor 223 that detects the displacement of the displacement mechanism 200a of the main pump 200, that is, the tilt angle (displacement volume) θo of the swash plate in the swash plate pump, A pressure sensor 224 for detecting a pump pressure Ps of the main pump 200, and a pump pressure Ps of the main pump 200 and a maximum load pressure P of the actuator taken out to the detection pipe 222.
A differential pressure sensor 225 that introduces Lmax and generates a signal corresponding to the differential pressure ΔPLS between the two.

Further, the hydraulic control device has pressure sensors 290 to 298 as means for detecting the operation pattern of the actuator. The pressure sensor 290 detects the pilot pressures a1 and a2 output from the pilot valve 210, and outputs an operation mode signal A of "turn". The pressure sensor 291 detects the pilot pressure b1 output from the pilot valve 211, and outputs an operation mode signal B for "boom raising". The pressure sensor 292 detects the pilot pressure b2 output from the pilot valve 211, and outputs an operation mode signal C for “boom lowering”.
Pressure sensor 293 detects pilot pressure c1 output from pilot valve 260, and outputs an operation mode signal D for "pull arm". The pressure sensor 294 detects the pilot pressure c2 output from the pilot valve 260, and outputs an operation mode signal E of “push arm”. The pressure sensor 295 detects the pilot pressure d1 from the pilot valve 261 and outputs an operation mode signal F for “bucket pull”. Pressure sensor 29
6 detects the pilot pressure d2 output from the pilot valve 261 and outputs an operation mode signal G of "bucket pressing". The pressure sensor 297 detects pilot pressures e1 and e2 output from the pilot valve 280, and outputs an operation mode signal H for “travel left”. Pressure sensor 298 is pilot valve 281
And outputs the pilot mode f1 and f2 output from the controller and outputs the "running right" operation mode signal I.

The above operation mode signals A to I have a role as an operation pattern signal of the actuator. For example, when only the operation mode signal A is output, it means an operation pattern of “turning alone”, and only the operation mode signal B is output. Is output, it means an operation pattern of "boom raising only", and when only the operation mode signals H and I are output, it is an operation pattern of "running only". Further, for example, when the combination of the operation mode signal B and the operation mode signal D is output, it means an operation pattern of “combined operation on the arm and boom”, typically “horizontal pull”. When a combination including the signal A and the operation mode signal D or E is output, it indicates an operation pattern of “turn and arm, other combined operation”, and a combination of the operation mode signal H and the operation mode signal I is output. Indicates the operation pattern of “running alone drive”, and when the combination of the operation mode signals H and I and other operation mode signals is output, “combined operation of traveling and other operations”, that is, “ It means that it is an operation pattern of "combined running".

The signals from the displacement sensor 223, the pressure sensor 224, the differential pressure sensor 225 and the signals A to I from the pressure sensors 290 to 298 are input to the controller 229, where the pump control signals S11, S12
And valve control signals S21, S22, S23, S24, S25, S26 are calculated,
These signals are output to the pump controller 209 and the electromagnetic proportional pressure reducing valves 216, 217, 266, 267, 286, 287, respectively.

The main pump 200 and the pump control device 209 constitute a pressure oil supply source.

FIG. 4 shows the configuration of the pump control device 209. The present embodiment is an example in which the pump control device 209 is configured as an electro-hydraulic servo hydraulic drive device.

The pump controller 209 includes a servo piston 230 that drives the displacement mechanism of the main pump 200, that is, the swash plate 200a.
, And the servo piston 230 is housed in the servo cylinder 321. The cylinder chamber of the servo cylinder 231 is divided into a left chamber 232 and a right chamber 233 by a servo piston 230, and a cross-sectional area D of the left 232 is a cross-sectional area d of the right chamber 233.
It is formed larger than.

The left chamber 232 of the servo cylinder 231 is connected to the pilot pump 220 via lines 234 and 235, and the right chamber 233 is connected to the pilot pump 220 via a line 235.
Lines 234 and 235 are connected to tank 208 via return line 236. An electromagnetic valve 237 is provided on the line 235, and an electromagnetic valve 238 is provided on the return line 236. These solenoid valves 237 and 238 are normally closed (a function to return to a closed state when not energized), and pump control signals S11 and S12 from the controller 229 are input thereto, and the solenoid valves 237 and 238 are thereby excited. And each is switched to the open position.

When the pump control signal S11 is input to the solenoid valve 237 and the solenoid valve 237 is switched to the open position, the left chamber 232 of the servo cylinder 231 communicates with the pilot pump 220, and the servo piston 230 moves rightward in the figure due to the area difference between the left chamber 232 and the right chamber 233. Move towards Thereby, the tilt angle of the swash plate 200a of the main pump 200, that is, the displacement is increased, and the discharge amount is increased. When the pump control signal S11 disappears, the solenoid valve 237 returns to the original closed position,
The communication between the left chamber 232 and the right chamber 233 is cut off, and the servo piston 230 is kept stationary at that position. As a result, the displacement of the main pump 200 is kept constant, and the discharge amount becomes constant. When the pump control signal S12 is input to the solenoid valve 238 and is switched to the closed position, the left chamber 232 and the tank 208
And the pressure in the left chamber 232 decreases, and the servo piston 230 moves leftward in the figure due to the pressure in the right chamber 233.
As a result, the displacement of the main pump 200 decreases, and the discharge amount also decreases.

Thus, the solenoid valves 237 and 238 are controlled by the pump control signals S11 and S12.
By controlling the displacement of the main pump 200 by controlling the displacement of the main pump 200, the displacement of the main pump 200 is controlled to match the target tilt angle θr calculated by the controller 229.

FIG. 5 is a block diagram showing a pump control signal calculation function 300 and a valve control signal calculation function 301 included in the controller 229 described above.

The pump control signal calculation function 300 includes a pump control gain calculation block 302, a target differential pressure calculation block 303, and a pump control unit 306. Pump control gain calculation block 302
Stores a plurality of sets of pump control gains that determine the response speed of the swash plate tilt of the main pump 200 during load sensing control in association with the operation mode signals A to I and their combinations (operation patterns), When the operation mode signals A to I are output from 290 to 298, the operation mode signals A to I are output.
And a set of control gains corresponding to the combination thereof. The target differential pressure calculation block 303 stores a plurality of target differential pressures ΔPLSr of the pump pressure Ps and the maximum load pressure PLmax at the time of the load sensing control in association with the operation mode signals A to I and a combination (operation pattern) thereof, Pressure sensor 290
When the operation mode signals A to I are output from .about.298, the target differential pressure corresponding to the operation mode signals A, .about.I and the combination thereof is selected. The pump control unit 306 includes pump control gain data and target differential pressure data output from the pump control gain calculation block 302 and the target differential pressure calculation block 303, respectively, a differential pressure signal ΔPLS, a pump pressure signal Ps, and a pump tilt signal θo. Based on the pump control signals S11, S
12 is calculated, and this is used as the solenoid valve 237, 238 of the pump controller 209.
Output to

The valve control signal calculation function 301 includes a control pressure variable calculation block 304, a control pressure change speed calculation block 305, and the valve control unit 30.
It has seven. The control pressure variable calculation block 304 converts a plurality of sets of variable data for a reference pattern (described later) of the pressure compensating valve control pressure stored as a function of the differential pressure signal ΔPLS into operation mode signals A to I and a combination thereof (operation pattern). ) Is stored, and when the operation mode signals A to I are output from the pressure sensors 290 to 298, a set of variable data corresponding to the operation mode signals A to I and a combination thereof is selected. The change speed calculation block 305 calculates the change speed of a plurality of sets of the pressure compensating valve control pressure by using the operation mode signals A to I.
And the combination (operation pattern) of the
When the operation mode signals A to I are output from the pressure sensors 290 to 298, a change speed of a set corresponding to the operation mode signals A to I and a combination thereof is selected. Valve control unit 307
Is the valve control signal S based on the variable data and the change speed data output from the control pressure variable calculation block 304 and the change speed calculation block 305, respectively, and the differential pressure signal ΔPLS.
Calculate 21 to S26 and apply this to the pressure compensating valves 205, 206, 255, 256, 2
Output to 75,276.

In the above-described pump control gain calculation block 302, target differential pressure calculation block 303, control pressure variable calculation block 304, and change speed calculation block 305, operation mode signals A to I associated with data stored therein and combinations thereof. The (operation pattern) is set to be the same, for example, and these include, for example, the aforementioned “turning only”, “boom raising only”, “running only”, “combined operation on arm pull and boom” typically "Horizontal pull", "Swirl and arm,
Each operation pattern of "another combined operation", "running and other combined operations", that is, "running combined" is included. The operation mode signals A to I associated with the stored data
The combination (operation pattern) may be different in each of the pump control gain calculation block 302, the target differential pressure calculation block 303, the control pressure variable calculation block 304, and the change speed calculation block 305.

Details of data stored in the pump control gain calculation block 302, the target differential pressure calculation block 303, the control pressure variable calculation block 304, and the change speed calculation block 305 are shown in FIGS.
This will be described with reference to FIG.

As shown in FIG. 6, the pump control gain calculation block 302 determines the number of the memory area corresponding to the operation mode signals A to I and the combination thereof (operation pattern), and determines the load considered to be optimal for each operation pattern. The increase gain LSU and the decrease gain LSD that determine the response speed of the pump displacement during the sensing control are stored in the memory area of the corresponding number. Operation mode signals A to I from pressure sensors 290 to 298
Is output, the number of the memory area corresponding to the operation mode signal and the combination thereof is referred to, and the gains LSU and LSD stored in the memory area are read.

The target differential pressure calculation block 303, as shown in FIG.
Operation mode signals A to I and their combinations (operation patterns)
The target differential pressure ΔPLSr at the time of load sensing control, which is considered to be optimal for each operation pattern, is stored in the memory area of the corresponding number. When the operation mode signals A to I are output from the pressure sensors 290 to 298, the numbers of the memory areas corresponding to the operation mode signals and the combinations thereof are referred to, and the target differential pressure ΔPLSr stored in the memory area is obtained. Is read.

Further, the control pressure variable calculation block 304 described above
As shown in the figure, the number of the memory area is determined corresponding to the operation mode signals A to I and their combination (operation pattern), and the reference pattern of the pressure compensating valve control pressure considered to be optimal for each operation pattern (described later) , A gain G, an offset O, a MAX limiter MA, and a MIN limiter MI are stored. When the operation mode signals A to I are output from the pressure sensors 290 to 298, the number of the memory area corresponding to the operation mode signal and the combination thereof is referred to, and the variable data stored in the memory area is read. .

Here, as described above, gain G, offset O, MAX
The limiters MA and MIN limiter MI are variables for the reference pattern of the pressure compensating valve control pressure, and the output pattern of the pressure compensating valve control pressure is determined from the reference pattern and these variable data. Hereinafter, this will be described in detail.

If the compensation pressure ΔPc of the pressure compensating valve is set to ΔPLS corresponding to the differential pressure signal ΔPLS, the differential pressure across the variable throttle incorporated in the directional control valve becomes ΔPLS, and the shunt ratio during the combined operation is It becomes the ratio of the opening amounts. The flow rate passing through the variable throttle of each directional control valve is expressed by the general formula Therefore, the pump flow rate Qp is Becomes

The compensation pressure ΔPc and the input differential pressure, that is, the differential pressure signal ΔPL
FIG. 9 shows the relationship with S as shown in FIG. Assuming that the characteristic line shown in FIG. 9 is a reference line, the flow rate is larger when the compensation pressure ΔPc is larger than the input differential pressure ΔPLS above the reference line shown in FIG. That is, when the compensation pressure ΔPc is smaller than the input differential pressure ΔPLS, the flow rate is smaller. Therefore, as for the flow rate, the upper side of the reference line has priority, and the lower side has no priority.

Here, in FIG. 1, for example, the pilot run-in
When the control pressure Pc led to 215 is increased, the pressure compensating valve 206 is increased.
, The compensation pressure ΔPc becomes smaller. Therefore, the relationship between the compensation pressure ΔPc and the control pressure Pc is reversed, and can be replaced with the reference line shown in FIG. In the reference line shown in FIG. 10, the upper side has no priority and the lower side has priority.

In the present embodiment, the reference line shown in FIG. 10 is stored as a reference pattern of the pressure compensating valve control pressure (described later), and gain G, offset O, MAX limiter MA, and MIN limiter MI are appropriately selected as variable data for this reference pattern. By doing so, a desired output pattern is obtained.

That is, the gain G is a variable for changing the inclination of the reference line shown in FIG. 10, and by multiplying the value, the characteristic changes as shown by the solid line in FIG.
Is a variable for moving the reference line in parallel. By adding the values, the characteristic changes as shown by a solid line in FIG. 12, and the MAX limiter MA sets the upper limit value of the reference line (the upper limit value of the control pressure Pc). ), The characteristic changes as shown by the solid line in FIG. 13 by changing the value, and the MIN limiter MI is set to the lower limit of the reference line (control pressure P
It is a variable for defining the lower limit of c). By changing the value, the characteristic changes as shown by the solid line in FIG. Gain G, offset O, MAX limiter MA, M
By appropriately selecting and combining the IN limiter MI,
A desired output pattern is obtained as shown in FIG.

By determining an output pattern using a combination of one reference pattern and its variable data as described above, it is possible to store the same number of output patterns with a smaller storage capacity as compared with a case where many output patterns are directly stored. Can,
The valve control means can be manufactured at low cost.

In addition, as shown in FIG. 16, the above-mentioned change speed calculation block 305 determines the number of the memory area corresponding to the operation mode signals A to I and their combination (operation pattern), and determines that the memory area is optimal for each operation pattern. The change speed in the closing direction KBMU... KTRU and the change speed in the opening direction KBMD. Pressure sensor 290
When the operation mode signals A to I are output from .about.298, the number of the memory area corresponding to the operation mode signal and the combination thereof is referred to, and the change speed data stored in the memory area is read.

Next, a detailed configuration of the pump control unit 306 shown in FIG. 5 will be described with reference to FIG.

In FIG. 17, the differential pressure signal output from the differential pressure sensor 225 shown in FIG. 1, that is, the input differential pressure ΔPLS, and the target differential pressure ΔPLS output from the target differential pressure block 303 shown in FIG.
The difference from r is calculated by the adder 311 as the differential pressure deviation ΔΔP (= ΔPLS−ΔPLS).
r). This differential pressure deviation ΔΔP is used together with the pump control gains LSD and LSU output from the pump control gain calculation block 302 shown in FIG.
Entered as 0. In this determination block 310, first, the sign of the differential pressure deviation ΔΔP is determined. Here, when ΔΔP is positive, the pressure difference is too large, so that the gain Lsc is set to the pump control gain LSD for reduction (LSc = LSD) in order to reduce the flow rate discharged from the main pump 200. , ΔΔP is negative, the differential pressure is too small, so the main pump
In order to increase the flow rate discharged from 200, the gain Lsc is set to a pump control gain LSU for increase (LSc = LSU) and output to the multiplier 312. The multiplier 312 multiplies the differential pressure deviation ΔΔP by the gain Lsc to increment the tilt ΔΔθ (=
An operation for obtaining (ΔΔP × LSc) is performed. That is,
When the differential pressure deviation ΔΔP is large or the gain Lsc is large, the tilt increment ΔΔθ is large, and the response of the swash plate tilt of the main pump 200, that is, the displacement increase / decrease is fast. Conversely, when the differential pressure deviation ΔΔP is small or the gain Lsc is small, the tilt increment ΔΔθ is small, and the response of the swash plate tilt increase / decrease of the main pump 200 is slow. The tilt increment ΔΔθ obtained in this way and the target tilt θr-1 a certain time τ seconds ago are added by the adder 313, and the target tilt θLS (= ΔΔθ + θr-1) of the load sensing control is calculated. Desired.

On the other hand, a motor 250 for driving the main pump 200 shown in FIG.
Is limited by the maximum horsepower, the maximum possible tilt θt corresponding to the pump pressure Ps is obtained by the function generator 314 as the target tilt for the horsepower limit control in order to perform the horsepower limit control of the motor 250. The minimum value of the target tilt θLS of the load sensing control and the target tilt θt of the horsepower limiting control obtained as described above is set to a minimum value selection block.
315, the pump tilt servo 3 is set as the target tilt θr.
Output to 16. In the pump displacement servo 316, the actual pump displacement θo output from the displacement sensor 223 shown in FIG.
And the target tilt θr described above, and the pump control signals S11 and S12 corresponding to the difference are supplied to the solenoid valve 23 shown in FIG.
Output to 7,238.

Next, a detailed configuration of the valve control unit 307 shown in FIG. 5 will be described with reference to FIG.

In FIG. 18, the function generator 320 stores the characteristics of the reference line shown in FIG. 10 as a reference pattern of the pressure control valve control pressure with respect to the input differential pressure ΔPLS. In this function generator 320, a control pressure Pc corresponding to the differential pressure signal ΔPLS output from the differential pressure sensor 225 shown in FIG. 1 is obtained and output to the multiplier 321. The multiplier 321 performs the above-described process of changing the inclination of the reference line shown in FIG. That is, the gain G output from the control pressure variable calculation block 304, for example, the gain GBM relating to the boom is multiplied by the control pressure Pc output from the function generator 320 to obtain a target control pressure Pc1, and the target control pressure Pc1 is obtained. Adder 32
Output to 6. In the adder 326, the above-described process of performing the parallel movement of the reference line shown in FIG. 12 is performed. That is, the offset O output from the control pressure variable calculation block 304, for example, the offset OBM relating to the boom and the target control pressure Pc1 output from the multiplier 321 are added to obtain a new target control pressure Pcr0, and this target control The pressure Pcr0 is output to the determination block 322 and the delay time processing block 323.

The delay time processing block 323 obtains a new target control pressure Pcr1 by multiplying the target control pressure Pcr0 output from the adder 326 by a first-order lag filter of the time constant TBM.
Output to

The calculation unit 324 performs the process of regulating the upper limit value and the lower limit value of the control pressure shown in FIGS. 13 and 14. That is, the MAX limiter MA and the MIN limiter MI output from the control pressure variable calculation block 304, for example, the MAX limiter MABM and the MIN limiter MIBM related to the boom and the target control pressure Pcr1 output from the delay time processing unit 323 are input, If the target control pressure Pcr1 is larger than the MIN limiter MIBM and smaller than the MAX limiter MABM, Pc3 = Pcr1, MIN
If smaller than limiter MIBM, Pc3 = MIBM, MAX limiter MA
If it is larger than BM, Pc3 = MABM is set, and this target control pressure Pc3 is output to the current value converter 325.

On the other hand, the decision block 322 includes the adder 326 as described above.
And the target control pressure Pcr−1 before τ seconds output from the delay time processing block 323.
And the control pressure change speed data output from the change speed calculation block 305 shown in FIG. 5, for example, the change speed KBMU in the closing direction and the change speed LBMD in the opening direction of the boom. In this decision block 322, first, Pcr0 and Pcr-1
Is determined, if Pcr0 ≧ Pcr-1, the target control pressure Pcr1 is in the decreasing direction, so that TBM = KBMD (change speed in the opening direction), and if Pcr0 <Pcr−1,
Since the target control pressure Pcr1 is in the increasing direction, TBM = KBMU
(Change speed in the closing direction), and the time constant TBM set in this way is input to the delay time processing unit 323. By setting the time constant in this way and obtaining a new target control pressure Pcr1 by applying a first-order lag filter in the delay time processing unit 323, the target control pressure Pcr1 input to the calculation unit 324 has an increasing direction and a decreasing direction. In each of the cases, a first-order lag corresponding to the closing direction changing speed LBMU and the opening direction changing speed KBMD is given, and the closing speed and the opening direction operating speed of the pressure compensating valve 206 are controlled. Sex can be controlled.

The current value converter 325 obtains a current value I corresponding to the target control pressure Pc3 from a preset relationship, and outputs the current value I to the electromagnetic proportional pressure reducing valve 217 as a valve control signal S22.

In the valve control unit 307, the valve control signals S21, S23 to S26 are similarly obtained for the other pressure compensating valves.

In the present embodiment configured as described above, when operating means such as the pilot valves 210 and 211 are operated, the pressure sensor 2
Operation mode signals A, B, C, etc. are output from 90, 291, 252, etc.,
This is input to the valve control signal calculation function 301 of the controller 229. In the valve control signal calculation function 301, the control pressure variable calculation block 304 selects the operation mode signal and the variable data corresponding to the combination (operation pattern), and the valve control unit 307 selects the variable data and the function generator 320. The output pattern of the pressure compensating valve control pressure is obtained from the reference pattern set in the step (1). Here, as described above, the output pattern of the control pressure can be set to a desired pattern by appropriately setting the variable data, that is, the gain G, the offset O, the MAX limiter MA, and the MIN limiter MI. Therefore, by setting this output pattern to a pattern that is considered optimal for each operation pattern, an optimum shunt ratio is given to the composite operation, for example, to ensure the independence of the operation between the actuators in the composite operation, and the operability is improved. it can.

In the valve control signal calculation function 301, together with the calculation of the output pattern, the control pressure change speed calculation block 305 selects the control pressure change speed data corresponding to the operation mode signal and its combination (operation pattern) at that time. The valve control unit 307 calculates the valve control signal by combining the change speed data with the control pressure obtained from the output pattern. Therefore, by setting the control pressure change speed so that the pressure compensating valve operates at the optimum response speed to the operation pattern at that time with respect to the change in the differential pressure signal, the pressure compensation when the differential pressure signal changes Excellent control of the dynamic responsiveness of the valve, thereby properly controlling the flow rate of the hydraulic oil supplied to the actuator when the differential pressure signal changes, without causing an unexpected sudden change in the actuator operating speed. Operability can be realized.

In the present embodiment, the pressure sensors 290, 291 and 252
The operation mode signals A, B, C, and the like output from the controller 229 are also input to the pump control signal calculation function 300 of the controller 229. In the pump control signal calculation function 300, the operation mode signals And the control gain data corresponding to the combination (operation pattern) are selected, and the pump control unit 306 uses the differential pressure deviation between the differential pressure signal and a preset target differential pressure and the control gain data to obtain the differential pressure. The pump control signal for reducing the deviation is calculated. Therefore, by setting the control gain so that the swash plate tilt of the hydraulic pump changes at a response speed optimal for the operation pattern at that time with respect to the change in the differential pressure signal, the change in the differential pressure signal Properly controlling the response speed of the swash plate tilt, and thereby properly controlling the flow rate of the pressure oil supplied to the actuator when the differential pressure signal changes, resulting in an unexpected sudden change in the actuator operation speed. Excellent operability can be realized.

Further, in the pump control signal calculation function 300, the operation mode signal and its combination (operation pattern) at that time are calculated in the target differential pressure block 303 together with the calculation of the control gain.
Is selected, and the pump control unit 306 uses the target differential pressure to calculate a pump control signal for reducing the differential pressure deviation. By setting the target differential pressure so as to obtain the optimal flow rate characteristics for the operation pattern at that time, the response to flow rate changes can be ensured, such as when the operation pattern is switched, pressure oil can be reliably supplied to the actuator on the high load side. Operability can be improved and excellent operability can be realized.

Next, specific examples of output patterns set for each of the above-described operation patterns will be described together with their specific effects.

First, in order to facilitate understanding of an operation pattern, a basic configuration of a hydraulic shovel on which the hydraulic control device of the present embodiment is mounted will be described with reference to FIGS. 19 and 20. Hydraulic excavator
Undercarriage 102 including left and right crawler tracks 100 and 101, and undercarriage
An upper revolving structure 103 is mounted on the upper revolving structure 103 so as to be capable of revolving, and a boom 104, an arm 105, and a bucket 106 constituting a front attachment mounted on the upper revolving structure 103 are provided. Left and right footwear 100, 101, revolving superstructure 103, boom 104, arm 105 and bucket 106 are respectively provided with left and right traveling motors 271, 27.
2. Driven by a swing motor 201, a boom cylinder 202, an arm cylinder 251 and a bucket cylinder 252.

[1] Operation pattern of traveling only (single) The operation levers 280a and 281a are operated, and the traveling motors 271 and 272 are operated.
Is an operation pattern in which the pressure sensors 297 and 298 are driven.
Output operation mode signals H and I.

The pump control gains LSu and LSd are set relatively small.
As a result, the starting and deceleration feeling of traveling are improved. Note that the target differential pressure ΔPLSr is set to a medium value (normal value).

As shown in FIG. 21, the MIN limiter MITR of the control pressure variable data is set small, the MAX limiter MATR is set large, and the gain GTR is set positive. As a result, the opening of the traveling pressure compensating valves 275, 276 is controlled to be larger than the reference when traveling straight, and the straight traveling performance is improved, and the opening of the traveling pressure compensating valves 275, 276 is controlled to be smaller than the reference during steering. Steering becomes easier.

Set the control pressure closing direction change speed KTRU to be small and the opening direction change speed LTRD to be large. Thereby, for example, when the speed is reduced during straight running, or when shifting from straight steering to straight running, the differential pressure between the pump discharge pressure and the maximum load pressure, that is, the LS differential pressure is transiently increased. Although it becomes smaller, the operation of the traveling pressure compensating valves 275 and 276 in the closing direction is delayed, so that the pressure is suddenly compensated and the traveling speed is prevented from changing. Further, at this time, since the pump control gain LSu is set to a small value as described above, the increase in the pump discharge flow rate is gradual, and the change in the traveling speed due to the sudden increase in the pump discharge flow rate is suppressed.

[2] Traveling composite operation pattern This is an operation pattern in which the operation levers 280a and 281a and any other operation levers are operated, and the traveling motors 271 and 272 and any other actuators are driven.
Output operation mode signals H and I, and a corresponding operation mode signal is output from another arbitrary pressure sensor.

The pump control gains LSU and LSD are set relatively small.
As a result, the traveling speed is suddenly increased, or the speed other than the traveling speed is suddenly increased. Target differential pressure Δ
Set PLSr to medium (normal value).

As shown in FIG. 22, the gain G of the actuator other than the running is set to be positive, and the gain GTR related to the running is set to be negative. Thereby, the opening of the pressure compensating valve related to the front forming the working machine is controlled to be smaller than the reference, and the opening of the traveling pressure compensating valves 275, 276 is controlled to be larger than the reference, so that the traveling priority is controlled. Is done.
Therefore, when operating the front while driving,
Extremely slow running is suppressed.

The closing speed LTRU and the opening direction changing speed KTRD of the control pressure related to traveling are set small, the closing direction changing speed of the control pressure other than traveling is set large, and the opening direction changing speed is set small. As a result, when the front is operated while traveling, the LS differential pressure is transiently reduced, but the operation of the traveling pressure compensating valves 275, 276 in the closing direction is delayed, thereby preventing a situation in which traveling is suddenly delayed. Therefore, when the load is lifted by the flot, the swing of the suspended load caused by the sudden change in the traveling speed is suppressed.

[3] Operation pattern of turning only (single) This is an operation pattern in which the operation lever 210a is operated and the turning motor 201 is driven, and the operation mode signal A is output from the pressure sensor 290.

Set the pump control gain LSU small and LSD large. As a result, the main pump slowly starts when turning
The discharge flow rate of 200 can be increased, thereby preventing jumping out, that is, sudden acceleration. In addition, since the turning speed can be returned quickly when decreasing, the increase in the discharge flow rate of the main pump 200 tends to be suppressed when the directional control valve vibrates due to the shaking of the vehicle body, so that the operation is stabilized. Target differential pressure ΔPL
Set Sr to medium (normal value).

As shown in FIG. 23, the values of the MAX limiter MASW and the MIN limiter MISW of the variable data of the control pressure related to turning are set to be the same. As a result, the control pressure Pc becomes constant regardless of the change in the input differential pressure ΔPLS, that is, the turning pressure compensating valve
The compensation pressure of 205 is constant, and the swing of the suspended load caused when the compensation pressure changes in the swing suspended load operation can be suppressed.

In this case, since the control pressure Pc is constant,
Since the control pressure Pc does not change due to the change in the LS differential pressure,
The changing speed in the closing direction and the changing speed in the opening direction of the control pressure are not set.

[4] Operation pattern of combined pulling (typically horizontal pulling) on the boom with arm pulling The operating levers 260a and 211a are operated and the arm cylinder 2
51 is an operation pattern in which the boom cylinder 202 is driven in the extension direction and the pressure sensors 293 and 29 are driven in the extension direction.
1 outputs operation mode signals D and B.

The pump control gain LSU is set large and the pump control gain LSd is set small. This makes it possible to increase the discharge flow rate of the main pump 200 quickly, raise the boom quickly in horizontal pulling, and prevent the tip of the toe from dropping. In addition, it is possible to delay the decrease in the discharge flow rate of the main pump 200 and prevent the toe from fluctuating when the boom is lowered during the horizontal pulling.

As shown in FIG. 24, among the control pressure variable data related to the arm, the MIN limiter MIAM is increased, and the MAX limiter MAAM is increased.
Is set small, the gain GAM is set positive, and the offset O
Set AM low. Also, the control pressure variable data related to the boom is larger for the MIN limiter MIBM, and for the MAX limiter MABM.
Large, gain GBM negative, and offset O
Increase BM. Accordingly, the opening of the arm pressure compensating valve 255 is controlled to a constant value smaller than the reference at the time of horizontal pulling, thereby preventing the tip of the toe from dropping. Further, at a light load in which the differential pressure ΔPLS does not become too small, the opening of the arm pressure compensating valve 255 is controlled to be smaller than the reference (arm non-priority control) to improve the rise of the boom. Further, during heavy excavation in which ΔPLS becomes extremely small, the opening degree of the arm pressure compensating valve 255 is controlled to be larger than the reference value, and pressure oil is sent preferentially to the arm cylinder 251 to improve work efficiency. Further, the opening of the boom pressure compensating valve 206 is controlled so as to be a constant value smaller than the reference during the horizontal pulling operation, so that the boom raising is prevented from fluctuating. Since the opening of the 206 is controlled to be larger than the reference, sufficient pressure oil is sent to the boom cylinder 202, and the fluctuation of the boom is similarly prevented.

The target differential pressure ΔPLSr set in the target differential pressure block 303 is set relatively high. This makes it possible to improve the boom lifting when performing the boom raising operation from the horizontal pulling mainly by the arm pulling.

The closing direction change speed KAMU of the control pressure related to the arm is set large, the opening direction change speed KAMD is set small, the closing direction change speed KBMU of the control pressure related to the boom is set small, and the opening direction change speed KBMD is set small. Thus, when the LS differential pressure ΔPLS suddenly decreases at the start of the horizontal pulling operation, the arm pressure compensating valve 255 is quickly throttled, so that the arm can be prevented from falling. Also, when the LS differential pressure ΔPLS suddenly increases, such as when the boom raising speed is suddenly reduced, the opening direction speed of the arm pressure compensating valve 255 is small, so that the arm operation is prevented from suddenly increasing. be able to. Further, since both the closing direction and the speed in the closing direction of the boom pressure compensating valve 206 are small, it is possible to improve the rise of the boom and prevent the boom from wobbling.

In the horizontal pulling, in the present embodiment, the pump control signal calculation function 300 and the flow rate control calculation function 301 are simultaneously calculated and output, so that a better operability can be secured by a synergistic effect of the two. it can.

[5] Single operation pattern on the boom This is an operation pattern in which the operation lever 211a is operated and the boom cylinder 202 is driven in the extension direction.
1 outputs an operation mode signal B.

Set the pump control gain LSU to medium and LSD low. Thus, it is possible to prevent the occurrence of a shock at the time of starting the boom raising, and to reduce the shock without suddenly delaying the raising of the boom when returning the operation lever. The target differential pressure ΔPLSr is set to a medium value (normal value).

As shown in FIG. 25, the values of the MAX limiter MABM and the MIN limiter MIBM of the control pressure variable data relating to the boom raising are set to be the same. As a result, the control pressure Pc becomes constant irrespective of the change in the input differential pressure ΔPLS, that is, the compensation pressure of the boom pressure compensation valve 206 becomes constant, and therefore, a boom speed corresponding to the lever operation is obtained, and the metering is improved. be able to.

Since the control pressure Pc is constant, the control pressure Pc does not change due to the change in the LS differential pressure, and thus the changing speed in the closing direction and the changing speed in the opening direction of the control pressure are not set.

[6] Operation pattern including turning and arm pulling At least the operation levers 210a and 260a are operated, the turning motor 201 is driven, and the arm cylinder 251 is driven in the extension direction. A and D are output. In addition, during this operation pattern, other than turning + arm pulling, turning + arm pulling + bucket pulling, turning + arm pulling + bucket pulling +
This includes the case where another work member is operating during simultaneous operation of turning and arm pulling, such as raising the boom.

Set the pump control gains LSU and LSD to medium. This improves the basic composite operability. Also, the target differential pressure ΔPLSr is set to a medium (normal value).

As shown in FIG. 26, the MIN limiter MISW of the control pressure variable data relating to turning is increased, the MAX limiter MASW is set large, the gain GSW is set negative, and the offset OSW is set large. Further, the MIN limiter MI of the control pressure variable data related to other than the turning is set large, the MAX limiter MASW is set large, the gain G is set positive, and the offset O is set small. As a result, the opening of the turning pressure compensating valve 205 is controlled to be larger than the reference, and the opening of the pressure compensating valve related to other than turning is controlled to be smaller than the reference. Pour pressure oil,
The turning pressure can be increased so that the turning does not escape during the turning press excavation.

The closing direction change speed KSWU of the control pressure related to turning is set to be small, the opening direction change speed KSWD is set to be large, the closing direction changing speed other than for turning is set to be large, and the opening direction change speed is set to be small. Thus, for example, when turning is started from pulling the arm and the LS differential pressure ΔPLS suddenly decreases, the closing direction speed of the turning pressure compensating valve 205 is small, and the closing direction speed of the arm pressure compensating valve 255 is fast. In addition, the turning pressure can be quickly maintained. Also, when the load of the arm pull is reduced during the turning and arm pulling work and the LS differential pressure ΔPLS suddenly increases, the opening direction speed of the arm pressure compensating valve 255 is small, so that the arm operation is rapidly increased. Can be prevented.

 Finally, some modifications of the above embodiment will be described.

First, in the above embodiment, a specialized pressure sensor was used for each actuator as the operation signal detecting means.
A part of the pressure sensor may be shared. FIG. 27 shows a modification thereof, in which a shuttle valve 403 is connected to two pilot lines related to the two directional switching valves 401 and 402 among the pilot lines connecting the operating lever device 400 and the two directional switching valves 401 and 402, The signal pressure taken out by the shuttle valve 403 is led to the pressure sensor 405, and the direction switching valves 401 and 40
2 is selectively detected as an operation signal. Pressure sensors 404 and 406 are disposed on the other two of the pilot lines, respectively, and individually detect driving in the other directions of the direction switching valves 401 and 402 as operation signals.

In the above embodiment, a pressure sensor was used as the operation signal detecting means. Instead of this pressure sensor, position sensors 412, 413 for detecting the strokes of the spools of the direction switching valves 410, 411 are provided as shown in FIG. May be adopted.

Further, in the above embodiment, the directional control valves 203, 204 and the like are driven by the pilot pressure. However, as shown in FIG. 29, the directional control valves 420, 421 are driven by the electric signal output from the electric lever 422. You may do it. In this case, the installation of the operation signal detecting means may be omitted. In this case, the electric signal output from the electric lever 422 is directly input to the controller 424 via the signal line 423, and the controller 424 directly outputs the actuator from the electric signal. The operation pattern of is identified.

Industrial Applicability Since the hydraulic control device for a construction machine of the present invention is configured as described above, when the LS differential pressure of the load sensing control changes, the flow rate of the pressure oil supplied to the actuator is changed. Is appropriately controlled, so that excellent operability with less shock can be realized.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Onoe 2625 Shimoinakichi, Chiyoda-mura, Niigata-gun, Ibaraki Prefecture Inside the dormitory in Tsukuba (72) Inventor Hideaki Tanaka 2-29-29 Ototominami, Tsuchiura City, Ibaraki Prefecture (72) Inventor Osamu Tomikawa 1--11-33, Shinto-Higashi, Tsuchiura-shi, Ibaraki 102 Urban light 102 (72) Inventor Masakazu Haga 1828 Chiyoda-mura, Shinji-gun, Ibaraki 1828 Chiyoda House 6-403 (72) Inventor Hiroshi Watanabe 1082--Tamiyacho, Ushiku-shi, Ibaraki 66 (56) References JP-A-2-1644941 (JP, A) JP-A-2-186105 (JP, A) JP-A-2-173468 (JP, A) JP-A-2-212601 (JP, A) JP-A-2-178427 (JP, A) JP-A-2-76904 (JP, A)

Claims (14)

(57) [Claims] 1. A variable displacement hydraulic pump (220), a plurality of actuators (201, 202 ...) driven by pressure oil supplied from the hydraulic pump, and a connection between the hydraulic pump and the actuator. Multiple valve means (20
205, 206 ...), and pump control means (209, 300) for controlling the displacement of the hydraulic pump such that the discharge pressure of the hydraulic pump is higher than the maximum load pressure of the plurality of actuators by a predetermined value. Each of the plurality of valve means changes a degree of opening in accordance with an operation signal from an operation means (210, 211 ...), and controls a flow rate of pressure oil supplied to a corresponding actuator (variable throttle ( 203,20
4 ...) and an auxiliary valve (205, 206 ...) that is arranged in series with the variable throttle and auxiliary controls the flow rate of the pressure oil supplied to the actuator. (A) first detecting means (224) for detecting a differential pressure between the discharge pressure of the hydraulic pump (220) and the maximum load pressure and outputting a corresponding differential pressure signal; and (B) the plurality of actuators. (201, 202...) Are detected, and the corresponding operation pattern signal (A-
(C) a valve control signal (S21-S) based on the differential pressure signal and the operation pattern signal output from the first and second detection means.
26), and valve control means (301) for controlling the driving of the auxiliary valves (205, 206 ...); and (a) controlling the auxiliary valve as a function of the differential pressure signal. A plurality of output patterns corresponding to the operation pattern signal, and when the operation pattern signal is output from the second detection means, an output pattern corresponding to the operation pattern signal is selected; The auxiliary valve control amount (Pc) corresponding to the differential pressure signal output from the first detection means above
And (b) storing a plurality of sets of change speeds of the auxiliary valve control amount in association with the operation pattern signal, and obtaining an operation pattern signal from the second detection means. A second means (305) for selecting, when output, a set of change speeds (K .., K ..) corresponding to the operation pattern signal; and (c) an auxiliary calculated by the first means. A third means (307) for calculating the valve control signal by combining the valve control amount and the change speed of the set selected by the second means; and a hydraulic control device for a construction machine. . 2. The hydraulic control system for a construction machine according to claim 1, wherein said first means (304, 307) comprises: (1) a reference pattern of said auxiliary valve control amount as a function of said differential pressure signal. (2) storing a plurality of sets of variable data for the reference pattern in association with the operation pattern signal (AI), and outputting an operation pattern signal from the second detection means; Means (304) for selecting a set of variable data corresponding to the operation pattern signal; and (3) obtaining the output pattern by combining the reference pattern and the selected set of variable data. Means (320, 321, 326, 323, 324) for calculating an auxiliary valve control amount corresponding to the differential pressure signal on an output pattern; and a hydraulic control device for a construction machine. 3. The hydraulic control apparatus for a construction machine according to claim 2, wherein the plurality of sets of variable data with respect to the reference pattern are a gain for changing the inclination of the reference pattern and an offset for moving the reference pattern in parallel. And a maximum value limiter for limiting the maximum value of the reference pattern and a minimum value limiter for limiting the minimum value of the reference pattern. 4. The hydraulic control apparatus for a construction machine according to claim 1, wherein said plurality of sets of change speeds stored by said second means (305) are respectively set to said auxiliary valves (205, 206 ...). )
A hydraulic control device for a construction machine, comprising: a change speed (KU) in a closing direction and a change speed (KD) in an opening direction. 5. The hydraulic control apparatus for a construction machine according to claim 4, wherein said third means (307) is adapted to control said auxiliary valve control amount calculated by said first means (307) by said auxiliary valve. (2
05,206 ...) is determined to be a value for operating in the closing direction or the opening direction. According to the determination result, one of the changing speed (KU) in the closing direction and the changing speed (KD) in the opening direction is determined. And selecting the change speed and the auxiliary valve control amount calculated by the first means to calculate the valve control signal (S21-S26). 6. A hydraulic control system for a construction machine according to claim 1, wherein said pump control means (300) comprises: (d) a plurality of sets of control gains (LSD, LSU) of said hydraulic pump (220). ) Is stored in association with the operation pattern signal (AI), and when the operation pattern signal is output from the second detection means (290-298), a set of control gains corresponding to the operation pattern signal A fourth means (302) for selecting (LSD, LSU); and (e) calculating a deviation between a differential pressure signal output from the first detecting means (225) and a preset target differential pressure. A pump control signal (S11, S12) for reducing the differential pressure deviation is calculated using the differential pressure deviation and the set of control gains (LSD, LSU) selected by the fourth means (302). Fifth means (306, 209) for controlling the displacement of the hydraulic pump (220) based on the signal And a hydraulic control device for a construction machine, comprising: 7. The hydraulic control system for a construction machine according to claim 6, wherein said plurality of sets of control gains stored by said fourth means (302) are respectively set to said hydraulic pump (220).
A hydraulic control device for a construction machine, comprising: an increase gain (LSU) suitable for controlling the displacement in a direction of increase and a decrease gain (LSD) suitable for controlling the direction of decrease. 8. The hydraulic control device for a construction machine according to claim 7, wherein said fifth means (306, 310) reduces the displacement of said hydraulic pump (220) in an increasing direction and in a decreasing direction. Direction is determined, and one of the increase gain and the decrease gain is selected according to the determination result, and the pump control is performed using the selected gain and the differential pressure deviation. A hydraulic control device for a construction machine, which calculates signals (S11, S12). 9. The hydraulic control apparatus for a construction machine according to claim 6, wherein said pump control means (300) comprises: (f) a plurality of discharge pressures of said hydraulic pump (220) and said maximum load pressure. The target differential pressure is stored in association with the operation pattern signal, and when the operation pattern signal (AI) is output from the second detecting means (290-298), the target corresponding to the operation pattern signal is output. Sixth means (303) for selecting a differential pressure, wherein the fifth means (306) uses the target differential pressure selected by the sixth means as the preset target differential pressure. A hydraulic control device for a construction machine. 10. The hydraulic control device for a construction machine according to claim 1, wherein said second detection means detects an operation signal output from each of said operation means and outputs a corresponding operation mode signal. A hydraulic control device for a construction machine, comprising an operation signal detecting means for outputting. 11. A variable displacement hydraulic pump (220), a plurality of actuators (201, 202...) Driven by pressure oil supplied from the hydraulic pump, and a connection between the hydraulic pump and the actuator. And the displacement of the hydraulic pump is controlled such that the discharge pressure of the hydraulic pump is higher than the maximum load pressure of the plurality of actuators by a predetermined value. Pump control means (209, 300), wherein each of the plurality of valve means changes an opening degree in accordance with an operation signal from the operation means (210, 211 ...), and controls the pressure oil supplied to the corresponding actuator. Variable throttle to control flow rate (203,20
4 ...) and an auxiliary valve (205, 206 ...) that is arranged in series with the variable throttle and auxiliary controls the flow rate of the pressure oil supplied to the actuator. (A) first detecting means (224) for detecting a differential pressure between the discharge pressure of the hydraulic pump (220) and the maximum load pressure and outputting a corresponding differential pressure signal; and (B) the plurality of actuators. (201, 202...) Are detected, and the corresponding operation pattern signal (A-
A second detection means (290-298) for outputting I), wherein the pump control means (300) comprises: (a) a plurality of sets of control gains (LSD, LSU) of the hydraulic pump (220); When the operation pattern signal is output from the second detection means (290-298) and stored in association with the operation pattern signal (AI), a set of control gains (LSDs) corresponding to the operation pattern signal is output. , LSU); and (b) determining a difference between a differential pressure signal output from the first detecting means (225) and a preset target differential pressure, and calculating the differential pressure. A pump control signal (S11, S12) for reducing the differential pressure deviation is calculated using the deviation and the set of control gains (LSD, LSU) selected by the first means (302). Second means (306, 209) for controlling the displacement of the hydraulic pump (220) based on the Hydraulic control system for a construction machine characterized. 12. The hydraulic control apparatus for a construction machine according to claim 11, wherein the plurality of sets of control gains stored in the first means (302) are respectively set to the hydraulic pump (22).
0) Increase gain (LSU) suitable for increasing displacement control and decreasing gain (LSD) suitable for decreasing displacement control
A hydraulic control device for a construction machine, comprising: 13. The hydraulic control system for a construction machine according to claim 12, wherein said second means (306, 310) reduces said displacement of said hydraulic pump (220) in an increasing direction and in a decreasing direction. Direction is determined, and one of the increase gain and the decrease gain is selected according to the determination result, and the pump control is performed using the selected gain and the differential pressure deviation. A hydraulic control device for a construction machine, which calculates signals (S11, S12). 14. The hydraulic control device for a construction machine according to claim 11, wherein said pump control means (300) comprises: (c) a plurality of discharge pressures of said hydraulic pump (220) and said maximum load pressure. The target differential pressure is stored in association with the operation pattern signal, and when the operation pattern signal (AI) is output from the second detecting means (290-298), the target corresponding to the operation pattern signal is output. Third means (303) for selecting a differential pressure, wherein the second means (306) uses a target differential pressure selected by the third means as the preset target differential pressure. A hydraulic control device for a construction machine.