JPH08135475A - Drive control device for construction machinery - Google Patents

Abstract

(57) [Abstract] [Purpose] A hydraulic drive system for a construction machine that prevents deterioration of operability by determining the amount of increase in the prime mover speed based on the load applied to the actuator and the set prime mover speed. To provide. A target rotation speed calculation device 51 for calculating a target rotation speed Nx of an engine, and a first correction rotation speed for calculating a first correction value ΔN1 (increase amount) of the engine rotation speed based on a pump discharge pressure Pp. Computing device 52 and target rotation speed Nx
The second correction rotational speed calculation device 53 for calculating the second correction value ΔN2 of the engine rotational speed based on the above, and the smaller one of the correction values ΔN1 and ΔN2 is selected, and the engine rotational speed correction value ΔN2 is selected. Correction speed selection device 5 for outputting as
4, the target rotation speed Nx and the engine rotation speed correction value ΔN are added to obtain a command value Ny of the engine rotation speed, and the engine rotation speed is controlled based on the command value Ny, whereby the hydraulic cylinder When the load acting on 32 exceeds a predetermined value, the engine speed is increased to prevent the operating speed of the hydraulic cylinder from decreasing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a construction machine, which is adapted to appropriately control the rotational speed of a prime mover of a construction machine such as a hydraulic excavator in accordance with an actuator load or the like.

[0002]

2. Description of the Related Art In a hydraulic drive system for performing full horsepower control, when the load on an actuator increases, the tilt angle of a variable displacement hydraulic pump decreases and the pump discharge flow rate decreases.
The operating speed of the actuator decreases. In order to prevent such a speed decrease, a hydraulic drive device that increases the rotational speed of a prime mover based on the load acting on the actuator, thereby increasing the pump discharge flow rate and preventing a decrease in the operating speed of the actuator, is disclosed. It is disclosed in Japanese Patent Laid-Open No. 63-167042.

7 to 10 show an example of such a conventional drive control device. 7 is a side view of the wheel hydraulic excavator, FIG. 8 is a configuration diagram of a prime mover rotation speed control device, FIG. 9 is a flowchart showing a processing procedure of the control device, and FIG. 10 is a PQ diagram. As shown in FIG. 7, the wheel type hydraulic excavator includes a lower traveling body 2 having traveling wheels 1, an upper revolving body 3 connected to the lower traveling body 2 via a revolving wheel, and an upper revolving body 3. The front attachment 4 is movably mounted. The front attachment 4 includes a boom 5, an arm 6, and a bucket 7, which are a boom cylinder 8, an arm cylinder 9, and a bucket cylinder 10, respectively.
Driven by.

A diesel engine (a prime mover) (not shown) is mounted on the upper-part turning body 3, and the rotation speed of the diesel engine is controlled by a prime mover speed control device shown in FIG. In FIG. 8, reference numeral 12 denotes a variable displacement hydraulic pump driven by the engine 11. The discharge pressure oil of the variable displacement hydraulic pump 12 causes the traveling motor for driving the traveling wheels 1 and the lower traveling body 2 to operate. On the other hand, a swing motor for driving the upper swing body 3, an actuator 13 including a boom cylinder 8, an arm cylinder 9, and a bucket cylinder 10 shown in FIG. 7 are driven. A control valve 14 is interposed between the variable displacement hydraulic pump 12 and the actuator 13, and the drive direction and speed of the actuator 13 are controlled by controlling the pressure oil supplied to the actuator 13 with the control valve 14. . 1
Reference numeral 5 denotes a load detection sensor that detects a load acting on the actuator 13, and the pressure of the pressure oil supplied from the control valve 14 to the actuator 13 (load pressure P).
To detect. Reference numeral 16 is a rotation speed detection sensor for detecting the engine rotation speed, 17 is a rotation speed control device for operating the governor lever of the governor 11a provided in the engine 11 to set the engine rotation speed, for example, a fuel lever or an accelerator pedal, and 18 is Is a rotation speed increasing / decreasing device that operates the governor lever separately from the fuel lever to increase / decrease the engine rotation speed, and is composed of, for example, a hydraulic cylinder (not shown). 19
Is a controller that controls expansion and contraction of the hydraulic cylinder of the rotation speed increasing / decreasing device 18 and adjusts the engine rotation speed based on signals from the rotation speed detection sensor 16 and the load detection sensor 15, and 20 is connected to the controller 19. This is an automatic control selection switch. When the switch is turned on, the engine speed increasing / decreasing device 18 controls the increase / decrease of the engine speed, and when it is turned off, the increase / decrease control is not executed.

The processing procedure of the conventional control device configured as described above will be described with reference to FIG. Controller 19
Reads the output values of the automatic control selection switch 20 and the load detection sensor 15 in step S1. In step S2,
It is determined whether or not the automatic control selection switch 20 is turned on. When the automatic control selection switch 20 is turned on, the process proceeds to step S3, and it is determined whether or not the load pressure P detected by the load detection sensor 15 exceeds a predetermined value Po.
If Po is exceeded, the process proceeds to step S5, where a command signal is output to the rotation speed increasing / decreasing device 18 to extend the hydraulic cylinder, and the engine speed N set by the fuel lever is increased by ΔN. Let On the other hand, if step S3 is denied, the process proceeds to step S4, and the hydraulic cylinder of the rotation speed increasing / decreasing device 18 is controlled to contract. Therefore, when the engine speed is N + ΔN, the engine speed is reduced by ΔN and returned to the speed N,
When the engine speed is N, that state is maintained. The same applies when step S2 is denied.

As described above, by increasing or decreasing the engine speed in accordance with the load pressure acting on the actuator, as shown in FIG.
A PQ diagram as shown in 0 is obtained. In FIG. 10, P− of the hydraulic pump 12 when the engine speed is N−
A Q-line is a one-dot chain line PQ1, a PQ-line of the hydraulic pump 12 is a two-dot chain line PQ2 at an engine speed N + ΔN in which the engine speed is increased by ΔN, and a flow rate control according to a load is performed in each P-Q line. Let the starting pressure be Pc (<Po).

When the hydraulic pump 12 is operated at the PQ diagram PQ1 corresponding to the engine speed N, the engine speed increases from N to N + ΔN when the load pressure exceeds Po, as shown by the solid line. Hydraulic pump 1 in PQ diagram PQ2
2 is driven. On the other hand, if the load pressure becomes Po or less while the hydraulic pump 12 is operating in the PQ diagram PQ2 corresponding to the engine speed N + ΔN, the engine speed N
+ ΔN to N, and as shown by the solid line, the P-Q diagram P
The hydraulic pump 12 is operated at Q1.

As can be seen from FIG. 10, the pump discharge flow rate obtained when the engine speed N is increased by ΔN does not exceed the maximum discharge flow rate Q1 of the hydraulic pump 12 at the engine speed N. ΔN is defined.

In the prior art thus constructed, the engine rotational speed is preset when the load pressure acting on the actuator is increased and the pump discharge flow rate is decreased, thereby slowing the operating speed of the actuator. The operation speed of the actuator is prevented from being slowed by increasing the pump discharge flow rate by increasing the predetermined amount.

[0010]

As described above, in the drive control device for a construction machine described in Japanese Patent Laid-Open No. 63-167042, the target rotational speed of the prime mover set by the fuel lever or the accelerator pedal. On the other hand, when the load acting on the actuator exceeds a predetermined value, the prime mover rotation speed increases by a certain amount regardless of the target rotation speed, and as a result, the road pressure travels on a flat road during climbing such that the load pressure P exceeds Po. A discharge flow rate equivalent to the maximum pump discharge flow rate at the time is secured. However, if the bucket collides with a large rock and the arm's actuator load increases during the leveling work that requires high work accuracy, the climbing speed is increased as described above with respect to the prime mover speed set by the fuel lever. Since the number of revolutions suitable for running increases, the pump discharge flow rate increases greatly, the operability is jerky, and the operation feeling is not good.

The present invention provides a drive control device for a construction machine, which prevents deterioration of operability by determining the prime mover speed to be increased according to the load applied to the actuator and the set prime mover speed. Is intended.

[0012]

The present invention will be described with reference to FIGS. 1 and 2 showing an embodiment. In the invention described in claim 1, a prime mover 31 and the prime mover rotation speed are set to target rotation speeds. Instruction means 36a, 36, 51 for instructing to set
A variable displacement hydraulic pump 30 driven by the prime mover 31 and an actuator 32 driven by pressure oil discharged from the variable displacement hydraulic pump 30.
And a load detection means 43 for detecting a load acting on the actuator 32, and, when correcting, a load of the actuator 32 detected by the load detection means 43 and a prime mover rotation speed information correlated with a prime mover rotation speed. The engine speed is adjusted to a speed obtained by correcting the target speed by the amount, and when not corrected, the engine speed is adjusted to the target speed instructed by the command means 36a, 36, 51. Means (52,5
3, 54, 55), the above-mentioned problems can be solved. According to a second aspect of the present invention, the rotational speed adjusting means (52, 53, 54, 55,) calculates the correction value of the target rotational speed based on the magnitude of the load detected by the load detecting means 43. Corrected rotation speed calculation means 52
And limiting means for limiting the correction value calculated by the correction rotation speed calculation means 52 such that it becomes smaller as the value of the prime mover rotation speed information is smaller, based on the magnitude of the value of the prime mover rotation speed information. (53, 54) and the correction means 55 for correcting the prime mover rotation speed with the correction value or the limited correction value. In the invention according to claim 3, the limiting means (53, 54) calculates the upper limit value proportional to the value of the prime mover rotation speed information, and the first upper limit value calculating means 53 and the corrected rotation speed calculating means 52. The selection means 54 selects the smaller one of the correction value calculated by the above and the upper limit value. According to a fourth aspect of the present invention, the limiting means (53, 54) is proportional to the value of the prime mover rotation speed information, second upper limit value calculating means 53d for calculating an upper limit value coefficient of 1 or less, and the correction. A multiplier 54a for multiplying the correction value calculated by the rotation speed calculation means 52 and the upper limit coefficient is provided. According to a fifth aspect of the present invention, the limiting means (53, 54) includes a third upper limit value calculating means 53e for calculating a subtraction value inversely proportional to a value of prime mover rotation speed information, and the correction rotation speed calculating means 52. And a subtractor 54b for subtracting the subtraction value from the calculated correction value. According to a sixth aspect of the present invention, the first upper limit value calculation means 53 has a plurality of correspondences between the value of the prime mover rotation speed information and the upper limit value, depending on the working state. According to a seventh aspect of the present invention, the second upper limit value calculating means 53d is provided with a plurality of correspondences between the value of the prime mover rotation speed information and the upper limit coefficient according to the working state. In the invention according to claim 8, the third upper limit value calculating means 53e is provided with a plurality of correspondences between the value of the prime mover rotation speed information and the subtraction value according to the working state. The invention according to claim 9 is
The prime mover rotation speed information is a target rotation speed of the prime mover commanded by the command means. According to a tenth aspect of the present invention, the prime mover rotation speed information is the actual rotation speed of the prime mover detected by the prime mover rotation speed detection means.

[0013]

According to the invention of claim 1, the rotation speed adjusting means (52,
53, 54, 55) corrects the target rotation speed of the prime mover based on the load Pp acting on the actuator 32 detected by the load detection means 43 and the prime mover rotation speed information when the rotation speed of the prime mover needs to be corrected. When the engine speed is adjusted to the specified engine speed and is not corrected, the engine speed is adjusted by the target engine speed commanded by the command means. According to the second aspect of the invention, the correction rotational speed calculation means 52 is
Based on the magnitude of the load detected by the load detecting means 43, the target rotation speed correction value ΔN1 is calculated. Further, the limiting means (53, 54) limits the correction value ΔN1 calculated by the correction rotation speed calculation means 52 so that it becomes smaller as the value of the prime mover rotation speed information becomes smaller. And the correction means 55
Adjusts the prime mover rotation speed based on the limited correction value ΔN. In the invention of claim 3, the first upper limit value calculating means 53 calculates and outputs the upper limit value ΔN2 proportional to the value of the prime mover rotation speed information. The selection means 54 uses the upper limit value ΔN2.
Then, the smaller one of the correction values ΔN1 calculated by the correction rotational speed calculation means 52 is selected and output to the correction means 55 as the correction value ΔN. According to the invention of claim 4, an upper limit coefficient ΔN3 of 1 or less proportional to the value of the engine speed information.
Is calculated and output by the second upper limit value calculation means 53d. The multiplier 54 a calculates the correction value ΔN by multiplying the correction value ΔN1 calculated by the correction rotation speed calculation means 52 by the upper limit coefficient ΔN3, and outputs the correction value ΔN to the correction means 55. In the invention of claim 5, the subtraction value ΔN inversely proportional to the value of the prime mover speed information
The third upper limit value calculation means 53e calculates 4 and outputs 4.
The differentiator 54b subtracts the subtraction value ΔN4 from the correction value ΔN1 calculated by the correction rotation speed calculation means 52 to calculate the correction value ΔN, and outputs it to the correction means 55. In the invention of claim 6, the first upper limit value calculating means 53 is provided with a plurality of correspondences between the value of the prime mover rotation speed information and the upper limit value ΔN2, and the correspondences are selected according to the working state. In the invention of claim 7, the second upper limit value calculation means 53d is provided with a plurality of correspondences between the value of the prime mover rotation speed information and the upper limit value coefficient ΔN3.
The correspondence is selected according to the work status. In the invention of claim 8, the third upper limit value calculating means 53e is provided with a plurality of correspondences between the value of the prime mover rotation speed information and the subtraction value ΔN4,
The correspondence is selected according to the work status. In the invention of claim 9, the target rotation speed of the prime mover commanded by the command means is used as the prime mover rotation speed information, and the rotation speed of the prime mover is corrected based on the target rotation speed Nx and the load of the actuator 32. According to the tenth aspect of the invention, the actual speed of the prime mover detected by the prime mover speed detecting means is used as the prime mover speed information, and the speed of the prime mover is corrected based on the actual speed Nr and the load of the actuator 32. is there.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a hydraulic circuit diagram constituting the present embodiment, and FIG. 2 is a block diagram of a control circuit unit in the hydraulic circuit shown in FIG. In FIG. 1, 30 is a variable displacement hydraulic pump driven by an engine 31, and 32 is a hydraulic cylinder driven by the hydraulic fluid discharged from the hydraulic pump 30 as a drive source. The hydraulic cylinder 32 drives a front attachment such as a boom, an arm, and a bucket of a hydraulic excavator, and the flow rate and direction of the supplied pressure oil are determined by a pipeline connecting the hydraulic pump 30 and the hydraulic cylinder 32. It is controlled by a control valve 34 interposed in 33.

The number of revolutions of the engine 31 is controlled by increasing / decreasing the fuel injection amount by operating the governor lever 31b of the governor 31a attached to the engine 31 by the pulse motor 35. The command signal to the pulse motor 35 is output from the controller 37, which will be described later, based on the signal from the rotation speed setting device 36 that calculates the displacement amount X according to the operation amount of the fuel lever 36a.

Tilt angle of the hydraulic pump 30 (pushing displacement)
Is controlled by the tilt angle control device 38. The tilt angle control device 38 includes a pilot hydraulic pump 39 that is driven by the engine 31 to discharge operating pressure oil, a servo cylinder 41 that determines a pump tilt angle based on a moving position of a piston, and a servo cylinder 41. The solenoid valve 40 controls the operating pressure oil to be supplied. The solenoid valve 40 includes a tilt angle sensor 42, a pressure sensor 43, and a rotation speed sensor 4 which will be described later.
Controller 3 based on the signal detected by 4 etc.
Switching is controlled by a signal output from 7.

The tilt angle sensor 42 detects the tilt angle θs of the hydraulic pump 30, the pressure sensor 43 detects the pump discharge pressure Pp of the hydraulic pump 30, and the rotation speed sensor 44 detects the engine rotation speed Nr. The operation amount Nθ of the governor lever 31b is detected by the potentiometer 45. Each of these detected values is input to the controller 37. Reference numeral 46 is a selection switch for selecting whether to output a correction value for the engine speed calculated by the controller 37 described later.

As shown in FIG. 2, the controller 37 is provided with a control circuit section 50, and the control circuit section 50 controls the engine speed. The control circuit unit 50 calculates the target rotation speed Nx of the engine from the displacement amount X calculated by the rotation speed setting device 36.
1 and the hydraulic pump 3 detected by the pressure sensor 43
The first engine speed based on the pump discharge pressure Pp of 0
Of the engine speed based on the target correction speed Nx calculated by the first correction speed calculation device 52 and the target rotation speed calculation device 51.
Second correction rotation speed calculation device 53 for calculating the correction value (increase amount) ΔN2 and the first and second correction rotation speed calculation device 5
First and second correction values ΔN calculated by 2, 53
1 and ΔN2 are compared with each other, the correction rotation speed selection device 54 that selects the smaller value and outputs it as the correction value ΔN, and the target rotation speed N calculated by the target rotation speed calculation device 51.
x and the correction value ΔN are added, and the engine speed command value Ny is added.
And an operation amount Nθ of the governor lever 31b detected by the potentiometer 45, and a switch 56 for switching on and off the signal output from the correction rotation speed selection device 54 to the adder 55 by the selection switch 46. The servo control unit 57 controls the pulse motor 35 based on the engine speed command value Ny.

The operation of the first embodiment thus constructed will be described. When the operator manually operates the fuel lever 36a, the displacement amount X of the fuel lever 36a is calculated from the rotation speed setting device 36 according to the operation amount. The displacement amount X, which is the output value of the rotation speed setting device 36, is input to the target rotation speed calculation device 51 of the control circuit unit 50, where the fuel lever 36
The target engine speed Nx for the displacement amount X of a is calculated. It should be noted that the target rotation speed calculation device 51, when the displacement amount X of the fuel lever 36a is 0, idling rotation speed N
i is output.

The target rotation speed Nx calculated by the target rotation speed calculation device 51 is input to the adder 55 and also to the second correction rotation speed calculation device 53, where the second correction of the engine rotation speed is performed. The value ΔN2 is calculated. The second correction value ΔN2 calculated by the second correction rotation speed calculation device 53 is determined according to the magnitude of the target rotation speed Nx, that is, the magnitude of the engine target rotation speed set according to the working state. It For example, in a work in which the actuator is operated at a low load and a low speed, such as a leveling work in which the engine speed is set low, the engine speed to be corrected is set low. In operations such as normal excavation / loading work in which the engine speed is set high and the actuator is operated at high load and high speed, the corrected speed is set high. Such a correction amount of the rotation speed is preset based on an empirical value and an experimental value.

The pump discharge pressure Pp of the hydraulic pump 30 detected by the pressure sensor 43 is controlled by the control circuit section 50.
It is input to the first corrected rotation speed calculation device 52 in the above. The pump discharge pressure Pp fluctuates in proportion to the magnitude of the load acting on the hydraulic cylinder 32. When the pump discharge pressure becomes equal to or higher than Pp1, the first correction rotation speed calculation device 52 has a first correction value Δ proportional to the pump discharge pressure.
When N1 is output and the load decreases, the first correction value ΔN1 is set to zero when the load becomes Pp2 or less. By providing the input / output relationship with hysteresis in this way, it is possible to prevent the first correction value ΔN1 from sequentially varying due to a slight variation in the pump discharge pressure.

The value of the first correction value ΔN1 calculated by the first correction rotation speed calculation device 52 is the engine rotation speed which corresponds to the decrease in the pump discharge flow rate according to the PQ characteristic due to the increase of the pump discharge pressure. Is set to a value that prevents the hydraulic cylinder 32 from operating at a lower speed due to a decrease in the pump discharge flow rate.
p2 is set in consideration of the decrease amount of the pump discharge flow rate due to the increase of the pump discharge pressure Pp, that is, the PQ characteristic. In addition, the pump 30 is
The control that reduces the tilt angle of the pump so that the pump absorption horsepower does not exceed a predetermined value is known as total horsepower control.

First and second correction values ΔN1 and ΔN2 calculated by the first and second correction rotation speed calculation devices 52 and 53.
Are input to the correction rotation speed selection device 54, and the smaller value is selected therein, and the engine rotation speed correction value ΔN
Is output as

The engine speed correction value ΔN is added to the engine target speed Nx which is the output value of the target speed calculation device 51 by the adder 55 when the switch 56 is turned on by the selection switch 46. , The engine speed command value Ny is output. This rotation speed command value N
y is input to the servo control unit 57. The engine speed based on the operation amount Nθ of the governor lever 31b detected by the potentiometer 45 is input to the servo control unit 57, and the servo control unit 57 compares the engine speed with the engine speed command value Ny. The pulse motor 35 outputs a signal for driving the governor lever 31b so that the engine speed matches the engine speed command value Ny.
Output to. As a result, the engine speed becomes the command value Ny.
Is controlled.

Here, when the switch 56 of the control circuit section 50 is turned off by the selection switch 46, the engine speed correction value ΔN is not output to the adder 55, so the engine speed is calculated as the target speed calculation. The target rotation speed Nx calculated by the device 51 is controlled.

According to the present embodiment constructed as described above, the following effects can be obtained. (1) The load acting on the hydraulic cylinder 32 is a predetermined pressure Pp1
As described above, the tilt angle of the hydraulic pump 30 decreases according to the PQ characteristics, the pump discharge flow rate decreases, and the drive speed of the hydraulic cylinder 32 decreases, but the engine speed increases in accordance with the load pressure. Since the decrease in the pump discharge flow rate is suppressed, the decrease in the drive speed of the hydraulic cylinder 32 can be prevented. (2) First and second correction values (increases) ΔN1 and ΔN2 of the engine speed based on the pump discharge pressure Pp and the target engine speed Nx, which fluctuate according to the load acting on the hydraulic cylinder 32. Is calculated, and the smaller one of these correction values is selected to select the engine speed correction value ΔN.
Therefore, when the engine speed is set low and the work is performed, even if the first correction value ΔN1 calculated due to the large load acting on the hydraulic cylinder 32 is large, the engine target If the second correction value ΔN2 based on the rotation speed Nx is smaller than the first correction value ΔN1, the second correction value ΔN2 is selected, so that a large engine rotation speed increases with respect to the initially set engine rotation speed. It is possible to prevent deterioration in operability due to a rapid increase in the pump discharge flow rate.

-Second Embodiment- The control circuit section 60 of the second embodiment will be described with reference to FIG.
The same components as those shown in FIG. 2 are designated by the same reference numerals, detailed description thereof will be omitted, and different points will be mainly described. In the second embodiment, the second correction rotation speed calculation device 53A for calculating the second correction value ΔN2 is used as the third correction rotation speed calculation device 53a and the fourth correction rotation speed calculation device 53a having different output characteristics.
Of the correction rotation speed calculation device 53b and the fifth correction rotation speed calculation device 53c, and a selection dial 61 for arbitrarily selecting them, and a third correction rotation speed calculation device selected by the selection dial 61. 53a, a fourth corrected rotation speed calculation device 53b, and a fifth corrected rotation speed calculation device 53
The control circuit unit 60 is configured by providing a changeover switch 62 for selectively supplying the target rotation speed Nx, which is the output value of the target rotation speed calculation device 51, to any one of c.

Incidentally, the third corrected rotational speed calculation device 53a,
The fourth correction rotation speed calculation device 53b and the fifth correction rotation speed calculation device 53c, for example, excavate a rock or the like in which a correction value is output for normal excavation and loading work with respect to the target rotation speed Nx. It corresponds to a mode b that outputs a correction value in heavy load excavation work and a mode c that outputs a correction value in low load excavation work such as leveling work, which are corrected according to changes in the target rotation speed Nx. The rate of increase in value (increase in engine speed) and the target speed at which the correction value begins to rise are varied depending on the work content.

The operation of the second embodiment constructed as above will be described. The control circuit unit 60 is controlled by the selection switch 46.
The switch 56 therein is turned on to turn on the engine speed correction control. Next, select switch 6 according to the work content
1 is operated to select one of the modes a, b, and c.
For example, as shown in the figure, when the mode a in the normal excavation and loading work is selected, the selection signal Y is output from the selection switch 61 and the changeover switch 62 is switched. As a result, the target rotation speed Nx output calculated from the target rotation speed calculation device 51 is input to the third corrected rotation speed calculation device 53a. The third correction rotation speed calculation device 53a calculates a second correction value ΔN2 based on the set target rotation speed Nx, and outputs the calculated value to the correction rotation speed selection device 54.

On the other hand, the pump discharge pressure Pp, which fluctuates according to the load acting on the hydraulic cylinder 32, is detected by the pressure sensor 43, and when the pressure becomes Pp1 or more, the first correction rotational speed calculation unit 52 makes the first correction. The output of the value ΔN1 is started, and the value is input to the correction rotation speed selection device 54.
Then, the correction rotation speed selection device 54 uses the first correction value ΔN1.
When the second correction value ΔN2 and the second correction value ΔN2 are input, the two are compared, the smaller value is selected, and the corrected rotation speed ΔN is output. When the corrected rotational speed ΔN is output to the adder 55 via the switch 56, the adder 55 adds the target rotational speed Nx set by the rotational speed setting device 36 and the corrected rotational speed ΔN. As a result, the engine speed is controlled to Nx + ΔN as described above.

When the other modes are selected by the selection dial 61, almost the same operation is performed.

As a result, in addition to the effects of the first embodiment,
Since the second correction value ΔN2 can be appropriately selected according to the work content, workability is improved.

In the second embodiment, the magnitude of the second correction value ΔN2 output according to the target rotation speed Nx can be selected according to the work content, but the first correction rotation speed calculation is performed. A plurality of devices having different set values of the reference pressures Pp1 and Pp2 of the device 52 and the output characteristics of the first correction value ΔN1 due to the variation of the discharge pressure Pp are prepared, and the selection dial 61 and the changeover switch 62 are provided as in the present embodiment. May be used to arbitrarily select them according to the work content.

In the embodiment described above, the potentiometer 4
Operation amount Nθ of the governor lever 31b detected by 5
Based on the engine speed command value N
Although the control is performed so as to match with y, a signal for operating the governor lever 31b is output to the pulse motor 35 so as to match the engine speed Nr detected by the speed sensor 44 with the engine speed command value Ny. You may do it. Further, the pulse motor 35 may be a servo motor.

Furthermore, the control circuit section 50 controls the correction rotation speed selection device 54 to use the first correction value ΔN1 and the second correction value Δ.
Although N2 is compared and the smaller value is output, instead of the second correction rotational speed calculation device 53 shown in FIG.
As shown in FIG. 4, a sixth corrected rotation speed calculation device 53d that calculates a coefficient ΔN3 of 1 or less based on the target rotation speed Nx.
Control for calculating the engine speed correction value ΔN in consideration of the engine speed by multiplying the first correction value ΔN1 which is the output value of the first correction speed calculation device 52 by the coefficient ΔN3 by the multiplier 54a. It may be the circuit unit 50a.

Further, as shown in FIG. 5, in place of the second correction rotation speed calculation device 53 shown in FIG. 2, a seventh correction rotation speed calculation for calculating a predetermined subtraction value ΔN4 based on the target rotation speed Nx. It is also possible to provide the device 53e and use it as the control circuit unit 50b for obtaining the engine speed correction value ΔN in consideration of the engine speed by subtracting the predetermined value ΔN4 from the first correction value ΔN1 by the differentiator 54b. .

As in the second embodiment shown in FIG. 2, the sixth and seventh correction rotational speed computing devices 53d, 53e shown in FIGS. 3 and 4 are composed of a plurality of output characteristics different from each other. It may be possible to select it appropriately according to the above.

These control circuit parts 50, 50a,
The second to seventh correction rotation speed calculation devices 53, 53a to 53e of 50b and 60 are the target rotation speed calculation device 51.
The second correction value ΔN2, the coefficient ΔN3 or the subtraction value ΔN4 is calculated on the basis of the target rotation speed Nx calculated by the above. The rotation speed sensor 44 detects the rotation speed sensor 44 like the control circuit unit 50c of FIG. It is also possible to calculate them based on the actual engine speed Nr of the engine, in which case a filter is provided between the engine speed sensor 44 and the second to seventh corrected engine speed calculation devices 53, 53a to 53e. Rotation speed sensor 4 that fluctuates little by little through 63
The output value of 4 may be stabilized.

Further, in the above-mentioned embodiments, the load detecting means of the actuator detects the pump discharge pressure by the pressure sensor 43. However, a physical quantity correlated with the load of the actuator, for example, an amount of change in engine speed, It may be detected by the pressure of pressure oil acting on the actuator. Furthermore, the case of the hydraulic cylinder has been described as an example of the actuator, but the present invention is not limited to this, and the present invention can be applied to a hydraulic motor used for traveling, turning, and the like.

In the above embodiment, the engine 31 is a prime mover, the fuel lever 36a, the rotation speed setting device 36, and the target rotation speed calculation device 51 are command means, the hydraulic cylinder 32 is an actuator, and the pressure sensor 43 is load detection. The first correction rotation speed calculation device 52 constitutes a correction rotation speed calculation means, the second correction rotation speed calculation device 53 and the correction rotation speed selection device 54 constitute a limiting means, and the adder 55 constitutes a correction means. To do.

[0042]

According to the present invention, since the tilt angle of the variable displacement hydraulic pump is reduced by the load acting on the actuator and the discharge flow rate is reduced, the driving speed of the actuator is prevented from being lowered. Since the increase / decrease amount of the prime mover is calculated based on the target revolution speed or the actual revolution speed as the revolution speed information and the load acting on the actuator, the prime mover rotates at a relatively low revolution speed. In this case, even if the load acting on the actuator is large, the increase / decrease in the number of revolutions of the prime mover is limited, and as a result, an excessive increase in the number of revolutions in accordance with the load on the actuator is prevented, which prevents operability from deteriorating. The driving speed of the actuator can be supplemented. Further, since the limit value of the rotation speed increase is made different according to the working state, it is possible to further finely increase the rotation speed and the workability is improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of a drive control device for a construction machine according to the present invention.

FIG. 2 is a block diagram showing details of a control circuit unit 50 of the first embodiment.

FIG. 3 is a block diagram showing details of a control circuit unit 60 of a second embodiment of the drive control device for a construction machine according to the present invention.

FIG. 4 is a block diagram showing a control circuit section 50a which is another example of the control circuit section 50 shown in FIG.

5 is a block diagram showing a control circuit section 50b which is another example of the control circuit section 50 shown in FIG.

FIG. 6 is a block diagram showing a control circuit section 50c which is another example of the control circuit section 50 shown in FIG.

FIG. 7 is a side view of a wheel hydraulic excavator showing an example of a construction machine to which the present invention is applied.

FIG. 8 is a configuration diagram of a control circuit of a drive control device for a construction machine according to a conventional technique.

9 is a control flow of the control circuit shown in FIG.

10 is a PQ diagram for explaining the control flow shown in FIG.

[Explanation of symbols]

 30 variable displacement hydraulic pump 31 engine 32 hydraulic cylinder 36 rotation speed setting device 36a fuel lever 37 controller 43 pressure sensor 51 target rotation speed calculation device 52 first correction rotation speed calculation device 53 second correction rotation speed calculation device 53A No. 2 correction rotation speed calculation device group 54 correction rotation speed selection device 55 adder 61 selection dial 62 changeover switch

Claims (10)

[Claims] 1. A prime mover, command means for instructing to set the prime mover speed to a target speed, a variable displacement hydraulic pump driven by the prime mover, and a variable displacement hydraulic pump. An actuator driven by pressure oil, a load detection means for detecting a load acting on the actuator, and when correcting, a motor rotation speed information correlated with the load of the actuator detected by the load detection means and a motor rotation speed While adjusting the prime mover rotation speed to a rotation speed that is obtained by correcting the target rotation speed by a corresponding amount, when not correcting, there is provided a rotation speed adjusting means for adjusting the prime mover rotation speed to the target rotation speed instructed by the command means. A drive control device for a construction machine, comprising: 2. The rotation speed adjusting means calculates a correction value of the target rotation speed based on the magnitude of the load detected by the load detecting means, and the correction rotation speed calculating means. The correction value calculated by the above, based on the magnitude of the prime mover rotation speed information, limiting means for limiting the correction value to be smaller as the value of the prime mover rotation speed information is smaller, and the correction value or the limited correction value. 2. The drive control device for a construction machine according to claim 1, further comprising: a correction unit that corrects the engine rotation speed. 3. The limiting means includes a first upper limit value calculating means for calculating an upper limit value proportional to a value of the prime mover rotation speed information, a correction value calculated by the correction rotation speed calculating means, and the upper limit value. The drive control device for a construction machine according to claim 2, further comprising a selection unit that selects a smaller one of the values. 4. The limiting means is a second upper limit value calculating means for calculating an upper limit value coefficient of 1 or less in proportion to the value of the prime mover rotation speed information, and a correction calculated by the correction rotation speed calculating means. The drive control device for a construction machine according to claim 2, further comprising a multiplier that multiplies a value by the upper limit coefficient. 5. The limiting means includes a third upper limit value calculating means for calculating a subtraction value inversely proportional to the target rotation speed, and a subtraction for subtracting the subtraction value from the correction value calculated by the correction rotation speed calculating means. The drive control device for a construction machine according to claim 2, further comprising: 6. The third upper limit value calculating means according to claim 3, wherein a plurality of correspondences between the value of the prime mover rotation speed information and the upper limit value are provided according to a working state. Drive control device for construction machinery. 7. The second upper limit value calculating means is provided with a plurality of correspondences between the value of the prime mover rotation speed information and the upper limit value coefficient, according to a working state.
The drive control device for the construction machine according to 1. 8. The construction according to claim 5, wherein the third upper limit value calculating means is provided with a plurality of correspondences between the value of the prime mover rotation speed information and the subtraction value according to a work state. Machine drive control device. 9. The drive control device for a construction machine according to claim 1, wherein the prime mover speed information is a target speed of the prime mover commanded by the command means. . 10. The drive of a construction machine according to claim 1, wherein the prime mover revolution number information is an actual revolution number of the prime mover detected by a prime mover revolution number detecting means. Control device.