JP2989749B2 - Drive control device for construction machinery - Google Patents

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 in which the rotation speed of a prime mover of a construction machine such as a hydraulic shovel is appropriately controlled in accordance with an actuator load or the like.

[0002]

2. Description of the Related Art In a hydraulic drive system that performs full horsepower control, when the load applied to an actuator increases, the tilt angle of a variable displacement hydraulic pump decreases and the pump discharge flow rate decreases.
The operation speed of the actuator decreases. In order to prevent such a decrease in speed, a hydraulic drive device that increases the rotation speed of a prime mover based on a load acting on an actuator, thereby increasing the pump discharge flow rate and preventing a decrease in the operation speed of the actuator is disclosed in Japanese Patent Laid-Open It is disclosed in JP-A-63-167042.

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

[0004] A diesel engine (motor) (not shown) is mounted on the upper swing body 3, and the rotation speed of the diesel engine is controlled by a motor rotation speed control device shown in FIG. 8. In FIG. 8, reference numeral 12 denotes a variable displacement hydraulic pump driven by an engine 11, and a discharge motor of the variable displacement hydraulic pump 12 drives a traveling motor for driving the traveling wheels 1 and a lower traveling body 2. On the other hand, a swing motor for driving the upper swing body 3 and 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 driving direction and speed of the actuator 13 are controlled by controlling the pressure oil supplied to the actuator 13 by the control valve 14. . 1
Reference numeral 5 denotes a load detection sensor for detecting 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).
Is detected. Reference numeral 16 denotes a rotation speed detection sensor that detects an engine rotation speed, 17 denotes a rotation speed control device that operates a governor lever of a governor 11a provided on the engine 11 to set the engine rotation speed, for example, a fuel lever or an accelerator pedal, and 18 denotes a rotation speed control device. This is a rotation speed increasing / decreasing device which operates the governor lever separately from the fuel lever to increase / decrease the engine speed, and is constituted by, 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 based on signals from the rotation speed detection sensor 16 and the load detection sensor 15 to adjust the engine rotation speed, and 20 is connected to the controller 19. This is an automatic control selection switch. When this switch is turned on, the engine speed is increased or decreased by the engine speed increase / decrease device 18, and when the switch is turned off, the increase / decrease control is not performed.

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. If the automatic control selection switch 20 is ON, the process proceeds to step S3, and it is determined whether the load pressure P detected by the load detection sensor 15 exceeds a predetermined value Po.
If it exceeds Po, the program proceeds to step S5, in which a command signal is output to the speed increasing / decreasing device 18 to extend the hydraulic cylinder, thereby increasing the engine speed N set by the fuel lever by ΔN. Let it. On the other hand, if step S3 is denied, the process proceeds to step S4, in which the hydraulic cylinder of the rotational 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, the state is maintained. The same applies when step S2 is denied.

[0006] By increasing or decreasing the engine speed in accordance with the load pressure acting on the actuator as described above, FIG.
A PQ diagram as shown in FIG. In FIG. 10, the P-
The Q diagram is a dashed line PQ1, the PQ diagram of the hydraulic pump 12 at the time of the engine speed N + ΔN when the engine speed is increased by ΔN is a two-dot chain line PQ2, and the flow rate control according to the load is performed in each PQ diagram. The starting pressure is defined as Pc (<Po).

When the hydraulic pump 12 is operated on the PQ diagram PQ1 corresponding to the engine speed N and the load pressure exceeds Po, the engine speed increases from N to N + ΔN, 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 becomes N
+ ΔN to N, and as indicated by the solid line, the PQ diagram P
The hydraulic pump 12 is operated at Q1.

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

In the prior art having such a configuration, when the load pressure acting on the actuator is increased and the pump discharge flow rate is reduced, thereby reducing the operating speed of the actuator, the engine speed is set in advance. By increasing the pump discharge flow rate by increasing the amount by a predetermined amount, the operation speed of the actuator is prevented from being reduced.

[0010]

As described above, in the drive control device for a construction machine described in Japanese Patent Application Laid-Open No. 63-167042, the target engine speed set by a fuel lever and an accelerator pedal is set. On the other hand, when the load acting on the actuator exceeds a predetermined value, the prime mover rotational speed increases by a fixed amount regardless of the target rotational speed. A discharge flow rate equal to the pump maximum discharge flow rate at the time is secured. However, if the work load requires high accuracy, for example, when the bucket collides with a large rock and the load on the actuator of the arm increases, the hill climbs as described above with respect to the engine speed set by the fuel lever. Since the number of revolutions suitable for traveling is increased, the discharge flow rate of the pump is greatly increased, the operability is jerky, and the operation feeling is not good.

The present invention provides a drive control device for a construction machine in which operability is prevented from deteriorating by determining a motor speed to be increased according to a load applied to an actuator and a set motor speed. It is intended to be.

[0012]

[Means for Solving the Problems]

(1) The present invention will be described with reference to FIGS. 1 and 2 showing an embodiment.
Instructing means 36 a, 36, 51 for instructing to set the motor rotation speed to the target rotation speed, a variable displacement hydraulic pump 30 driven by the prime mover 31, and a discharge from the variable displacement hydraulic pump 30. An actuator 32 driven by pressure oil;
Load detecting means 43 for detecting a load acting on the motor, and the motor 31 based on the load detected by the load detecting means 43.
Variable displacement hydraulic pump 3 so as not to exceed the output horsepower of
Displacement volume adjusting means 41 for adjusting the displacement volume of 0;
The present invention is applied to a drive control device for a construction machine having rotation speed adjusting means 55 and 57 for adjusting the rotation speed of the prime mover 31 based on the target rotation speed. Then, according to the load Pp of the actuator detected by the load detecting means 43 and the motor speed information correlated with the motor speed, the smaller the motor speed information, the smaller the upper limit value is limited to a correction value. Correction value calculation means 52, 5 for calculating ΔN
3, 54, and the rotation speed adjusting means 55, 57 adjusts the rotation speed of the prime mover so that the rotation speed becomes a rotation obtained by correcting the target rotation speed Nx based on the correction value ΔN. The problem is solved. (2) The invention according to claim 2 is characterized in that the correction value calculation means includes a correction rotation number calculation means 52 for calculating a correction value ΔN1 of the target rotation number based on the load Pp detected by the load detection means 43. An upper limit value calculating means 53 for calculating an upper limit value ΔN2 proportional to the value of the motor speed information, and a correction value ΔN calculated by the corrected speed calculating means 52.
1 and a selecting means 54 for selecting the smaller one of the upper limit value ΔN2 and outputting the correction value ΔN. (3) Explaining in connection with FIG. 4, the invention according to claim 3 is characterized in that the correction value calculating means is replaced by the load detecting means 43.
Correction speed calculating means 52 for calculating a correction value ΔN1 of the target speed based on the load Pp detected by
An upper limit coefficient calculating means 53d for calculating an upper limit coefficient ΔN3 of 1 or less in proportion to the value of the motor rotation speed information, and a correction value ΔN calculated by the correction rotation speed calculation means 52
1 and the upper limit coefficient ΔN3 to obtain the correction value ΔN
And a multiplier 56 that outputs (4) Explaining in connection with FIG. 5, the invention according to claim 4 is characterized in that the correction value calculating means is replaced by the load detecting means
Correction speed calculating means 52 for calculating a correction value ΔN1 of the target speed based on the load Pp detected by
A subtraction value calculating means 53e for calculating a subtraction value ΔN4 inversely proportional to the target rotation speed; and a subtractor for subtracting the subtraction value ΔN4 from the correction value ΔN1 calculated by the correction rotation speed calculation means to output the correction value ΔN. 54b. (5) The invention according to claim 5, wherein the upper limit value calculating means 5
Numeral 3 is provided with a plurality of correspondences between the value of the motor rotation speed information and the upper limit value according to the work state. (6) According to a sixth aspect of the present invention, the upper limit coefficient calculating means 53d has a plurality of correspondences between the value of the motor rotation speed information and the upper limit coefficient in accordance with a working state. (7) The invention according to claim 7, wherein the subtraction value calculation means 5
Reference numeral 3e includes a plurality of correspondences between the value of the motor rotation speed information and the subtraction value according to the work state. (8) In the invention described in claim 8, the motor speed information is the target engine speed specified by the command means. (9) According to a ninth aspect of the present invention, the motor speed information is the actual motor speed detected by the motor speed detector.

[0013]

[Action]

(1) According to the first aspect of the invention, the correction value calculating means 52, 5
The corrections 3 and 54 limit the upper limit value to a smaller value as the motor speed information is smaller, in accordance with the motor speed information correlated with the engine load Pp detected by the load detecting means 43 and the motor speed. The value ΔN is calculated.
The rotation speed adjusting means 55 and 57 adjust the rotation speed of the prime mover 31 so that the target rotation speed is corrected based on the correction value ΔN. (2) According to the second aspect of the invention, the corrected rotational speed calculating means 52
Calculates the correction value ΔN1 of the target rotation speed based on the load Pp detected by the load detection means 43. The upper limit value calculating means 53 calculates an upper limit value ΔN2 proportional to the value of the prime mover speed information. The selector 54 selects the smaller one of the correction value ΔN1 calculated by the correction rotation speed calculator 52 and the upper limit ΔN2, and outputs the correction value ΔN. The rotation speed adjusting means 55 and 57 adjust the rotation speed of the prime mover 31 so that the target rotation speed Nx is corrected based on the correction value ΔN. (3) According to the third aspect of the invention, the corrected rotational speed calculating means 52
Calculates a correction value ΔN1 of the target rotational speed based on the load detected by the load detecting means 43. The upper limit coefficient calculator 53d calculates an upper limit coefficient ΔN3 of 1 or less in proportion to the value of the motor rotation speed information. The multiplier 56 multiplies the correction value ΔN1 calculated by the correction rotation speed calculating means 52 by the upper limit coefficient ΔN3 to output the correction value ΔN. (4) According to the fourth aspect of the invention, the corrected rotational speed calculating means 52
Calculates a correction value ΔN1 of the target rotational speed based on the load Pp detected by the load detecting means 43. The subtraction value calculating means 53e calculates a subtraction value Δ in inverse proportion to the target rotation speed.
N4 is calculated. The subtracter 54b outputs the correction value ΔN by subtracting the subtraction value ΔN4 from the correction value ΔN1 calculated by the correction rotation speed calculation means 52. (5) In the invention of claim 5, the upper limit value calculating means 53 is provided with a plurality of correspondences between the value of the motor rotation speed information and the upper limit ΔN2, and selects the correspondence in accordance with the work state. (6) According to the invention of claim 6, the upper limit coefficient calculating means 53d
Are provided with a plurality of correspondences between the value of the motor rotation speed information and the upper limit coefficient ΔN3, and the correspondence is selected according to the work state. (7) According to the seventh aspect of the present invention, the subtraction value calculation means 53e is provided with a plurality of correspondences between the value of the motor rotation speed information and the subtraction value ΔN4, and selects the correspondence in accordance with the work state. (8) According to the eighth aspect of the present invention, the target rotation speed of the prime mover instructed by the command means is set as the rotation speed information of the prime mover, and the rotation speed of the prime mover is corrected based on the target rotation speed Nx and the load Pp of the actuator 32. . (9) According to the ninth aspect of the invention, the actual rotation speed of the prime mover detected by the prime mover rotation speed detecting means is used as the prime mover rotation speed information, and the actual rotation speed Nr and the load Pp of the actuator 32 are set.
The rotation speed of the prime mover is corrected based on the above.

In the means and means for solving the above problems which explain the constitution of the present invention, in order to make the present invention easy to understand, the drawings of the embodiment are used. However, the present invention is not limited to this.

[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 of the present embodiment, and FIG. 2 is a block diagram of a control circuit in the hydraulic circuit shown in FIG. In FIG. 1, reference numeral 30 denotes a variable displacement hydraulic pump driven by an engine 31, and reference numeral 32 denotes a hydraulic cylinder driven by using the discharge pressure oil of 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 shovel. 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. Controlled by a control valve 34 interposed in 33.

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

The tilt angle (displacement volume) of the hydraulic pump 30
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 movement position of a piston, and a servo cylinder 41. And an electromagnetic valve 40 for controlling the supplied operating pressure oil. The solenoid valve 40 includes a tilt angle sensor 42, a pressure sensor 43, and a rotation speed sensor 4 described later.
4 based on a signal detected by the controller 3 or the like.
The switching is controlled by a signal output from the switch 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 rotational speed sensor 44 detects the engine rotational speed Nr. The operation amount Nθ of the governor lever 31b is detected by the potentiometer 45. These detected values are input to the controller 37. Reference numeral 46 denotes a selection switch for selecting whether to output a correction value of the engine speed calculated by the controller 37 described later.

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

The operation of the first embodiment configured as described above will be described. When the operator manually operates the fuel lever 36a, the displacement 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 50, where the fuel lever 36
The target engine speed Nx for the displacement X of a is calculated. When the displacement X of the fuel lever 36a is 0, the target rotation speed calculating device 51 calculates the idling rotation speed N
i.

The target rotation speed Nx calculated by the target rotation speed calculation device 51 is input to an adder 55 and also to a 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. You. For example, in an operation in which the actuator is operated at a low load and at a low speed, such as a normalizing operation in which the engine speed is set low, the corrected engine speed is set low. In an operation such as a normal excavation / loading operation in which the engine speed is set high and the actuator is operated at a high load and a high speed, the rotation speed to be corrected is set high. Such a correction amount of the rotational speed is set in advance 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 50.
Is input to the first corrected rotation speed calculation device 52. The pump discharge pressure Pp varies 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 calculating device 52 sets a first correction value Δ proportional to the pump discharge pressure.
The first correction value ΔN1 is set to zero when the load becomes lower than Pp2 when N1 is output and the load decreases. By providing hysteresis in the input / output relationship in this manner, the first correction value ΔN1 is prevented from successively changing due to a slight change in the pump discharge pressure.

The value of the first correction value ΔN1 calculated by the first correction rotation speed calculation device 52 is determined by calculating the decrease in the pump discharge flow rate according to the PQ characteristic due to the increase in the pump discharge pressure by the engine speed. Is set to a value that prevents a decrease in the operating speed of the hydraulic cylinder 32 due to a decrease in the pump discharge flow rate.
p2 is set in consideration of the amount of decrease in the pump discharge flow rate due to the increase in the pump discharge pressure Pp, that is, the PQ characteristic and the like. It should be noted that the pump 30 pressure is increased by increasing the pump discharge pressure.
Is controlled so that the pump absorption horsepower does not exceed a predetermined value by reducing the tilt angle of the vehicle.

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

If the switch 56 is turned on by the selection switch 46, the engine speed correction value ΔN is added to the engine target speed Nx, which is the output value of the target speed calculator 51, by the adder 55. Is output as the engine speed command value Ny. This rotational 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. Then, a signal for driving the governor lever 31b is set so that the engine speed matches the engine speed command value Ny.
Output to As a result, the engine speed becomes equal to the command value Ny.
Is controlled.

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

In this embodiment configured as described above, the following effects can be obtained. (1) The load acting on the hydraulic cylinder 32 is a predetermined pressure Pp1
With the above, the tilt angle of the hydraulic pump 30 decreases according to the PQ characteristic, the pump discharge flow rate decreases, and the driving speed of the hydraulic cylinder 32 decreases, but the engine speed increases in accordance with the load pressure. Since a decrease in the pump discharge flow rate is suppressed, a decrease in the driving speed of the hydraulic cylinder 32 can be prevented. (2) First and second correction values (increase amounts) ΔN1, ΔN2 of the engine speed based on the pump discharge pressure Pp that fluctuates according to the load acting on the hydraulic cylinder 32 and the target engine speed Nx, respectively. Is calculated, and the smaller one of these correction values is selected to determine the engine speed correction value ΔN
Therefore, when the operation is performed with the engine speed set low, even if the first correction value ΔN1 calculated due to a 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 the engine rotation speed that is larger than the initially set engine rotation speed increases. Therefore, it is possible to prevent the operability from being deteriorated due to a sudden increase in the pump discharge flow rate.

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

It should be noted that the third corrected rotation speed calculating device 53a,
The fourth corrected rotation speed calculation device 53b and the fifth corrected rotation speed calculation device 53c excavate rocks and the like, for example, in mode a for outputting a correction value in normal excavation and loading work for the target rotation speed Nx. Mode b for outputting a correction value in heavy-load excavation work, and mode c for outputting a correction value in low-load excavation work such as leveling work, respectively, and these are corrections corresponding to changes in the target rotation speed Nx. The ratio of the increase in the value (the amount of increase in the engine speed) and the target speed at which the correction value starts rising are changed depending on the work content.

The operation of the second embodiment configured as described above will be described. The control circuit 60 is controlled by the selection switch 46.
Is turned on to turn on the engine speed correction control. Next, select switch 6 according to the work content
1 to select one of the modes a, b, and c.
For example, as shown in the drawing, when the mode a in the normal excavation and loading operation 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 corrected rotation speed calculation device 53a calculates a second correction value ΔN2 based on the set target rotation speed Nx, and outputs the value to the corrected rotation speed selection device 54.

On the other hand, a 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 equal to or higher than Pp1, the first correction rotation speed calculating device 52 performs 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 number selecting device 54 outputs the first correction value ΔN1
When the second correction value ΔN2 and the second correction value ΔN2 are input, a smaller value is selected by comparing the two, and is output as the correction rotation speed ΔN. When the corrected rotation speed ΔN is output to the adder 55 via the switch 56, the adder 55 adds the target rotation speed Nx set by the rotation speed setting device 36 and the corrected rotation speed ΔN. Thus, the engine speed is controlled to Nx + ΔN, as described above.

The operation is substantially the same when other modes are selected by the selection dial 61.

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. A plurality of units are prepared in which the 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 fluctuation of the discharge pressure Pp are changed, and a selection dial 61 and a changeover switch 62 as in the present embodiment. And may be arbitrarily selected according to the work content.

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

Further, the control circuit unit 50 sets the correction rotation number selecting device 54 to the first correction value ΔN1 and the second correction value ΔN1.
N2, and the smaller value is output. However, instead of the second corrected rotation speed calculator 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 in which the multiplier 54a multiplies the first correction value ΔN1 which is the output value of the first correction rotation speed calculation device 52 by the coefficient ΔN3, and calculates the engine rotation speed correction value ΔN in consideration of the engine rotation speed. The circuit section 50a may be used.

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

The sixth and seventh corrected rotational speed calculating devices 53d and 53e shown in FIGS. 3 and 4 are constituted by a plurality of units having different output characteristics, similarly to the second embodiment shown in FIG. May be selected as appropriate.

The control circuit units 50, 50a,
The second to seventh correction rotation speed calculating devices 53, 53a to 53e of 50b and 60 are provided with a target rotation speed calculating device 51.
The second correction value ΔN2, the coefficient ΔN3, or the subtraction value ΔN4 is calculated based on the target rotation speed Nx calculated according to the above. It is also possible to calculate them based on the actual engine speed Nr of the engine to be executed. In this case, a filter is provided between the engine speed sensor 44 and the second to seventh correction engine speed calculators 53 and 53a to 53e. The rotation speed sensor 4 that fluctuates little by little with the intervention of 63
4 may be stabilized.

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

In the above embodiment, the engine 31 detects the prime mover, the fuel lever 36a, the rotational speed setting device 36, and the target rotational speed calculating device 51 detect the command means, the hydraulic cylinder 32 detects the actuator, and the pressure sensor 43 detects the load. The first correction rotation speed calculation device 52, the second correction rotation speed calculation device 53, and the correction rotation speed selection device 54 perform the correction value calculation means, and the first correction rotation speed calculation device 52 performs the correction rotation speed calculation. The second corrected rotation speed calculating device 53 is an upper limit value calculating device, the corrected rotation speed selecting device 54 is a selecting device, the sixth corrected rotation speed calculating device 53d is an upper limit coefficient calculating device, The correction rotation speed calculation device 53e constitutes a subtraction value calculation means.

[0042]

According to the present invention, it is possible to prevent the drive speed of the actuator from decreasing due to the decrease in the tilt angle of the variable displacement hydraulic pump due to the load acting on the actuator and the decrease in the discharge flow rate. Since the increase / decrease amount of the prime mover speed is calculated based on the target rotational speed or the actual rotational speed as the rotational speed information and the load acting on the actuator, a state where the prime mover rotates at a relatively low rotational speed is used. At times, even if the load acting on the actuator is large, the amount of increase or decrease in the number of rotations of the prime mover is limited, and as a result, an excessive increase in the number of rotations according to the load on the actuator is prevented, thereby reducing the operability. The driving speed of the actuator can be compensated. Further, since the limit value of the increase in the number of revolutions is made different according to the working state, the number of revolutions can be more finely increased, and the workability is improved.

[Brief description of the 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 illustrating details of a control circuit unit 50 according to 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 construction machines according to the present invention.

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

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

FIG. 6 is a block diagram showing a control circuit unit 50c which is another example of the control circuit unit 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 the related art.

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

FIG. 10 is a PQ diagram for explaining a control flow shown in FIG. 9;

[Explanation of symbols]

 Reference Signs List 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 Correction rotation speed calculation device group 2 54 Correction rotation speed selection device 55 Adder 61 Selection dial 62 Changeover switch

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-51502 (JP, A) JP-A-61-4848 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 29/04 F02D 41/04 F02D 45/00

Claims (9)

(57) [Claims] 1. A motor, command means for instructing setting of the rotation speed of the motor to a target rotation speed, a variable displacement hydraulic pump driven by the motor, and discharge from the variable displacement hydraulic pump. An actuator driven by pressurized oil, load detection means for detecting a load acting on the actuator, and the variable displacement hydraulic pump based on the load detected by the load detection means so as not to exceed the output horsepower of the prime mover. A displacement control means for adjusting a displacement capacity of the engine, and a rotational speed adjusting means for adjusting the rotational speed of the prime mover based on the target rotational speed. According to the detected motor load and the motor speed information correlated to the motor speed, the smaller the motor speed information, the smaller the motor speed information. A correction value calculation unit that calculates a correction value whose upper limit is limited by a small value, wherein the rotation speed adjustment unit adjusts the rotation speed of the prime mover so that the rotation speed becomes the rotation speed obtained by correcting the target rotation speed based on the correction value. A drive control device for a construction machine, wherein the drive speed is adjusted. And a correction value calculation means for calculating a correction value of the target rotation speed based on the load detected by the load detection means, wherein the correction value calculation means calculates a correction value of the target rotation speed based on a load detected by the load detection means. Upper limit value calculating means for calculating the corrected upper limit value, and selecting means for selecting the smaller one of the correction value calculated by the correction rotation speed calculating means and the upper limit value and outputting the correction value. The drive control device for a construction machine according to claim 1, wherein: 3. A correction value calculating means for calculating a correction value of the target rotation number based on the load detected by the load detecting means, a correction value calculating means for calculating a correction value of the target rotation speed in proportion to a value of the motor speed information. And an upper limit coefficient calculating means for calculating an upper limit coefficient of 1 or less, and a multiplier for multiplying the correction value calculated by the correction rotation speed calculating means and the upper limit coefficient to output the correction value. The drive control device for a construction machine according to claim 1, further comprising: 4. A correction value calculating means for calculating a correction value of the target speed based on a load detected by the load detecting means, and a subtraction value inversely proportional to the target speed. 2. A subtraction value calculation means for calculating the correction value, and a subtractor for subtracting the subtraction value from the correction value calculated by the correction rotation speed calculation means and outputting the correction value. Drive control device for construction machinery. 5. The construction machine according to claim 2, wherein said upper limit value calculating means includes a plurality of correspondences between a value of said motor rotation speed information and said upper limit value according to a work state. Drive control device. 6. The construction according to claim 3, wherein said upper limit coefficient calculating means has a plurality of correspondences between the value of said engine speed information and said upper limit coefficient according to a working state. Machine drive control. 7. The construction machine according to claim 4, wherein said subtraction value calculation means has a plurality of correspondences between the value of said motor rotation speed information and said subtraction value, according to a working state. Drive control device. 8. The drive control device for a construction machine according to claim 1, wherein said motor speed information is a target speed of a motor designated by said command means. . 9. The construction machine drive according to claim 1, wherein said motor speed information is an actual motor speed detected by a motor speed detecting means. Control device.