JPH02279837A - Device for controlling revolution speed of prime mover for hydraulic construction machine - Google Patents

Abstract

PURPOSE:To improve fuel consumption and to reduce noises by a method wherein operation of an operating lever of a hydraulically driven car is adjusted and discharge flow of an oil-hydraulic pump is regulated thereby and operation of an actuator is further adjusted thereby, resulting in controlling the revolution speed of a prime mover. CONSTITUTION:The title device is constructed of a prime mover 1, a variable displacement oil-hydraulic pump 6, an actuator 8 driven by the oil-hydraulic pump 6, a torque regulator 6a controlling output torque of the oil-hydraulic pump 6 and of the prime mover 1, and a regulating valve 7 regulating these devices. Then a necessary rotation speed of the prime mover is sought with load pressure applied to the actuator 8 by making adjustment to operation of an operating lever 10. The rotation speed is obtained by operation made with a value at the point of load pressure where the line of constant discharge flow of the pump intersects the line of constant horsepower of the prime mover 1 controlled by the torque regulator 6a. Thereby improvement can be made for fuel consumption and, at the same time, reduction of noises becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION A. INDUSTRIAL APPLICATION FIELD The present invention relates to a prime mover rotation speed control device for hydraulic construction machinery, typified by hydraulic excavators.

B. Conventional technology Conventionally, this type of prime mover rotation speed control device was disclosed in Japanese Patent Application Laid-open No. 62
The one disclosed in Japanese Patent No. 94622 is known.

This prime mover rotation speed control device detects the operation amount of the work lever to determine the required flow rate of the hydraulic actuator, and based on this required flow rate, changes the engine speed to the low rotation and high efficiency side, and adjusts the pump discharge volume (hereinafter referred to as tilt rotation). This is to control the angle (referred to as the angle) to a high-inclination, high-efficiency side, thereby improving fuel efficiency and reducing noise.

C1 Problems to be Solved by the Invention However, this conventional device has the following problems.

■When both the engine speed and the pump tilt angle are electronically controlled as one set based on the detected operation amount of the work lever, if an abnormality occurs in the controller, control becomes impossible. Furthermore, control becomes complicated, leading to increased costs.

■If you control either the engine speed or the pump tilt angle, you will not get the desired effect.

The technical problem of the present invention is to: 1) In a hydraulic construction machine equipped with a torque regulator, it is possible to simultaneously control the discharge volume of a hydraulic pump by controlling only the prime mover rotation speed to an optimum value based on the operation amount of a work lever; to obtain hydraulic efficiency equivalent to that of

■In hydraulic construction machinery equipped with a rotation speed setting means for setting the set rotation speed of the prime mover, optimal matching of this set rotation speed and the required rotation speed calculated based on the required flow rate and load pressure of the actuator. To take, there is.

Means for Solving the Problems 00 To be explained with reference to a diagram showing an embodiment, the present invention comprises a variable displacement hydraulic pump 6 driven by a prime mover 1, and at least a variable displacement hydraulic pump 6 driven by a pressure oil discharged from the hydraulic pump 6. One actuator 8 and a torque regulator 6 that controls the absorption torque of the hydraulic pump 6 to be lower than the output torque of the prime mover by a predetermined value so that the prime mover 1 does not stall.
a, and a control valve 7 that controls the pressure oil from the hydraulic pump 6 and controls the drive of the actuator 8 in accordance with the operation of the operating member 10. be done.

As shown in FIG. 2, the apparatus of claim 1 includes a required flow rate detection means 21 for detecting the required flow rate of the actuator 8 in accordance with the operation of the operating member 1o, and a pressure detection means for detecting the load pressure of the actuator 8. means 9; and calculation means for calculating the required rotational speed of the prime mover 1 such that the constant pump discharge flow rate line determined by the required flow rate of the actuator 8 and the constant horsepower curve of the prime mover 1 controlled by the regulator 6a intersect at the load pressure point. 22 and a rotation speed control means 24 for controlling the rotation speed of the prime mover 1 to the required rotation speed. In addition, as shown in FIG. 6, the required flow rate detection means 21 is provided.

A rotation speed control means 24, which includes a pressure detection means 9 and a calculation means 22, and controls the rotation speed of the prime mover 1 to the larger of the required rotation speed and the set rotation speed set by the rotation speed setting means 13a. As shown in FIG. rotation speed control means 23, 2 for controlling the rotation speed of the prime mover 1 to a smaller value of both after a predetermined time period when the difference between the two becomes greater than or equal to a predetermined value;
4,28,29°30.31 solves the above technical problem.

The required flow rate of the actuator 8 is determined according to the operation amount of the E1 effect operation member 10, and the required rotation speed is determined according to this required flow rate and the load pressure of the actuator 8. This required rotation speed is calculated as a value such that the constant pump discharge flow rate line determined by the required flow rate and the constant horsepower curve of the prime mover controlled by the torque regulator intersect at the load pressure point, so the fuel consumption rate can be improved. At the same time, noise can also be reduced.

As in claim 3, if the larger of the required rotation speed and the set rotation speed is set as the target rotation speed, then by setting the set rotation speed to an appropriate value greater than or equal to a predetermined value, it becomes the lower limit of the rotation speed, Frequent fluctuations in the engine speed can be prevented, which is advantageous in terms of fuel consumption and noise.

According to claim 4, if the smaller of the required rotation speed and the set rotation speed is set as the target rotation speed after a predetermined time after the difference between the required rotation speed and the set rotation speed becomes equal to or greater than a predetermined value, the set rotation speed is set to a large value. However, since the prime mover can rotate at a relatively low target rotation speed, it is advantageous in terms of fuel consumption and noise.

In the above-mentioned sections and section E, which describe the present invention in detail, figures of embodiments are used to make the present invention easier to understand, but the present invention is not limited to the embodiments.

F. Example 1.First embodiment- A first embodiment will be explained with reference to FIGS. 1 to 5.

FIG. 1 shows the overall configuration of a prime mover rotation speed control device, and the rotation speed of a diesel engine (prime mover) 1 is controlled by a governor 1a. The governor 1a is connected to a pulse motor 3 by a link mechanism 2, and is driven according to the rotation of the pulse motor 3 to control the engine rotation speed. A potentiometer 5 is connected to the governor 1a by a link mechanism 4, and its rotational position is detected as a governor lever position detection value No. described later and input to the controller 20. The rotation of the pulse motor 3 is controlled by a motor drive signal from the controller 20.

On the other hand, the flow rate and direction of the oil discharged from the variable displacement hydraulic pump 6 driven by the engine 1 is controlled by the control valve 7 and guided to the actuator 8 . The unit discharge volume q of the variable displacement hydraulic pump 6 is determined by the torque regulator 6a as a function of the pump pressure pp as shown in FIG. The discharge pressure of the hydraulic pump 6 is detected by a pump pressure sensor 9 and inputted to the controller 20 as pump pressure Pp.

The work lever 1o controls the control valve 7 by operating a pilot valve 11 that outputs a pilot pressure according to the amount of operation thereof. The pilot valve 11 reduces the hydraulic pressure from the pilot hydraulic pump 15 driven by the engine 1 according to the amount of operation, and the pilot pressure is detected by the pilot pressure sensor 12.
is detected and inputted to the controller 20 as the pilot pressure Pi. Further, the fuel lever 13 has a rotation speed setter 13a that outputs a set rotation speed N1 proportional to the amount of operation thereof, and the rotation speed command N1 is transmitted to the controller 20.
is input. Further, the selection switch 14 has two modes: a first mode in which the engine is controlled at a set rotation speed N2 set by the fuel lever 13, and a second mode in which the engine rotation speed is controlled according to the operating amount of the work lever 10, as will be described later. This is a switch to select one of the modes.

The controller 20 is configured as shown in FIG.

The function generator 21 receives the pilot pressure signal Pi from the pilot pressure sensor 12 and outputs a required flow rate Q according to the operation amount of the work lever 10. The required rotation speed calculator 22 is
Using this required flow rate Q and the pump pressure signal Pp from the pump pressure sensor 9, the required rotation speed N2 is calculated as shown below.

First, the pump unit discharge volume (tilting amount) q is determined as a function of the pump pressure Pp as shown in FIG. 3, as described above, and is expressed using the pump input torque T as follows. Further, the required rotation speed N2 is expressed by the pump tilting amount q and the required flow rate Q1. Therefore, according to equations (1) and (2), where 4 to 3 are constants, and when pump input torque T is expressed as a function of engine rotation speed, equation (3) becomes as follows.

Referring again to FIG. 2, the selector 23 is connected to the selection switch 14.
When is off, the normally closed contact closes and changes the set rotation speed N from the rotation speed setting device 13a to the target rotation speed N.

When the selection switch 14 is on, the normally closed contact closes and the required rotation speed N2 becomes the target rotation speed N.

Output as .

A servo control unit 24 outputs a control signal for the pulse motor 3 according to the deviation between the target rotation speed N and the governor lever position signal No detected by the potentiometer S. The servo control unit 24 includes a deviation device 241 that calculates the deviation A between the target rotation speed N and the governor lever position signal No., an absolute value calculation circuit 242 that calculates the absolute value of the deviation A, and a difference between the IAI and the reference rotation speed. It is composed of a comparator 243 that compares the values and outputs a high 1 novel when IAI≧ and a low level otherwise, and an AND gate 244 that is enabled by the high level output of the comparator 243 and outputs the deviation A. .

The motor driver 25 drives the pulse motor 3 by the deviation A.
A pulse motor drive signal for forward or reverse rotation is formed and input to the pulse motor 3.

When AI<K, the AND gate 244 outputs the low 1 novel and the pulse motor 3 is stopped.

The operation of the first embodiment configured in this way will be explained with reference to FIGS. 4 and 5.

Figure 4 shows engine rotation speed N a = 2000r, P
, Im, , Nb= 250 Or, p, o, , Nc=
300 Or, p, m.

Fig. 5 shows a P-Q (pump pressure car pump discharge flow rate) diagram, and Fig. 5 shows an N-PS diagram, an N-T diagram, an N-
A g-diagram is shown for each.

Now, set the set rotational speed N to Nb using the fuel lever 13, and set the required flow rate Q1 by operating the work lever 10 to Q.
Assuming that the pump pressure PP becomes P2 at the same time as c, the hydraulic pump 6 is operated at D on the PQ line of the engine speed Nb.
The discharge flow rate of the hydraulic pump 6 becomes QD, and the desired required flow rate Qc cannot be obtained.

Next, assume that the pump pressure Pp becomes Po.

Assuming that the engine speed is constant Nb, the hydraulic pump 6 is
Matching occurs at point A on the P-Q line of the engine rotation speed Nb, and the discharge flow rate of the hydraulic pump 6 becomes Q2. therefore,
The flow rate of (Q, -Qc) will be returned to the tank,
Hydraulic efficiency is poor. On the other hand, if well-known load sensing control is used in the hydraulic circuit shown in FIG. Match at point B above,
Hydraulic efficiency is improved. However, the engine speed is Nb
There is room to improve the fuel consumption rate as described below.

In Fig. 5, the governor 1a is set to B (B'), and if the pump load (engine output) is PSL and the engine speed is matched to Nb, the fuel consumption rate is determined from each diagram in Fig. 5. It becomes g2. If 1, here, the governor 1a is set to A (A'), the engine speed will be matched with the optimum Na for the output horsepower PS1, and the fuel consumption rate can be reduced to 1.

Therefore, the engine speed is controlled as follows.

(2) At pump pressure P2, the engine speed is controlled so that the hydraulic pump 6 matches at the intersection E of the constant required flow rate Qc line and the constant output horsepower line of the engine speed.

Thereby, the engine speed is controlled to NG, and the desired required flow rate Qc is obtained.

■Next, at pump pressure P0, pump discharge flow rate Q
Intersection B between the c constant line and the constant engine speed output horsepower line
The engine speed is controlled so that the hydraulic pump 6 is matched. As a result, the engine speed is controlled to Na, and the fuel consumption rate at engine output horsepower PS□ is g
□, and fuel efficiency improves by (gz-g).

In the first embodiment, in which the engine speed is controlled to the optimum value based on the operating amount of the work lever 1o, the desired flow rate can always be obtained within the engine pump's capacity range, and statically the hydraulic efficiency is improved. is optimized, reducing fuel consumption and noise.

Note that the controller 20 may calculate the unit discharge volume q from the pump discharge pressure Pp, and electronically control the torque regulator 6a to obtain the p-q characteristic shown in FIG. 3.

However, in construction machines such as hydraulic excavators, the lever 1o is frequently operated during one operation.

The engine speed also frequently fluctuates between a low speed range and a high speed range accordingly. Therefore, a) there is a large energy loss due to acceleration of the engine flywheel, and not only does fuel efficiency not improve much, but
It gets worse depending on driving conditions.

Although the engine speed increases in conjunction with the operation of the work lever 10, the time required for this is considerably longer than the operation time of the work lever 10, and there is a time lag for the hydraulic actuator to reach the desired speed.

c) Black smoke is generated due to frequent fluctuations in engine speed.

2) Frequent engine speeds are harsh and cause discomfort to the operator.

Therefore, second to sixth embodiments that solve such problems will be described below.

- Second Embodiment - FIG. 6 shows a block diagram of the controller 20 in a second embodiment. The same parts as in FIG. 2 are denoted by the same reference numerals, and the explanation will focus on the differences.

A maximum value selection circuit 26 is provided in place of the switch 23, and the larger of the required rotation speed N2 and the set rotation speed N is selected as the target rotation speed N3. therefore.

The selection switch 14 is also abolished.

As a result, the lower limit value of the target rotation speed N becomes the set rotation speed N
1, so if the set rotational speed N is set to a value above a predetermined value that is optimal for the work, the engine rotational speed will not fluctuate frequently, which is advantageous in terms of fuel consumption and noise. In the embodiment shown in FIG. 6, by setting the set rotational speed N to an optimum value that matches the work, the above-mentioned time lag can be reduced and the desired actuator acceleration can be obtained.

-Third Embodiment- FIG. 7 shows a block diagram of the controller 20 in a third embodiment, and parts similar to those in FIG. 2 are given the same reference numerals, and the explanation will focus on the differences.

Instead of switching the selector 23 using the selection switch 14, switching is performed using the output of the function generator 27. The normally closed contact of the switch 23 is closed so that the required rotation speed N2 is selected when the required flow rate Q1 is greater than a predetermined value, and the normally closed contact of the switch 23 is closed so that the selected rotation speed N1 is selected when the required flow rate Q1 is less than the predetermined value. Close the contact Now, if the predetermined value of the above-mentioned required flow rate Q1 is the upper limit of the metering area of the control valve 7, the engine will rotate at the set rotation speed N in the metering area, and when it exceeds the metering area. , the engine rotates at the required rotational speed N8. Therefore, fluctuations in engine speed within the metering range can be prevented, noise can be reduced, and operability can be improved. In addition, in a region beyond the metering region, the engine rotates at a rotation speed corresponding to the required flow rate, improving fuel efficiency. In addition, in one normal operation, a large proportion of the operation is performed within the metering range, so frequent fluctuations in the engine speed are small and the above-mentioned problems are solved.

- Fourth Embodiment - FIG. 8 shows a block diagram of a controller 20 in a fourth embodiment. The same parts as in FIG. 2 are given the same reference numerals, and the explanation will focus on the differences.

In this embodiment, when a predetermined period of time has elapsed after the deviation between the set rotation speed N□ and the required rotation speed N3 exceeds a predetermined value,
The smaller value of either the set rotation speed Ni or the required rotation speed N2 is selected as the target rotation speed N3.

Therefore, the controller 20 according to this embodiment includes an i-differential device 28 that measures the deviation ΔN between the set rotation speed N1 and the required rotation speed N2, a timer 29, and a timer 29 that starts the timer 29 when ΔN is greater than or equal to a predetermined value. Function generator 30 and set rotation speed N1
and a minimum value selection circuit 31 that selects the smaller value of the required number of revolutions N2, and the switch 23 has a normally closed contact that is closed until the timer 29 measures a predetermined time, and a normally closed contact that is closed when the timer 29 measures a predetermined time. The contacts are configured to close.

In such an embodiment, when the same load condition continues for a predetermined time or more, the normally closed contact of the switching device 23 is closed and the required rotation speed N2 is selected as the target rotation speed N3. therefore,
When the work lever 10 is operated frequently, the engine rotates at the set rotation speed N set by the fuel lever 13, preventing frequent fluctuations in the engine rotation speed, and improving fuel efficiency.
This is advantageous in terms of noise. Furthermore, when the vehicle continues to be operated under relatively low load conditions, fuel efficiency improves and noise also decreases.

- Fifth Embodiment - FIG. 9 shows a block diagram of a controller 20 in a fifth embodiment. The same parts as in FIG. 2 are given the same reference numerals, and the explanation will focus on the differences.

In this embodiment, the required rotation speed N2 is selected via the switch 23 when the pilot pressure Pi is greater than or equal to a predetermined value and the pump pressure PP is less than a predetermined value. Therefore, the controller 20 according to this embodiment includes a function generator 32 that outputs 1 when the pilot pressure Pi is equal to or higher than a predetermined value, and a function generator 3 that outputs 1 when the pump pressure Pp is less than the predetermined value.
3 and an AND gate 34 which takes the AND of both function generators 32 and 33, and when the AND gate 34 is at a low level, the switch 23 is made a normally closed contact to select the set rotation speed N□, and when the high level is At times, the necessary rotation speed N2 is selected by using the switch 23 as a normally closed contact.

According to such an embodiment, the engine is controlled by the required rotation speed N2 only when the load is low and outside the metering range, so the engine rotation speed does not fluctuate frequently, which is advantageous in terms of fuel consumption and noise. .

-Sixth Embodiment- FIG. 10 shows a block diagram of a controller 20 in a sixth embodiment, and parts similar to those in FIG. 2 are denoted by the same reference numerals, and the explanation will focus on the differences.

This embodiment is effective for, for example, running control of a wheeled hydraulic excavator, and the required rotation speed calculation circuit calculates the required flow rate Q determined by the discharge pressure of a pilot valve connected to a running pedal, etc., and the pump pressure Pp. The target rotation speed N is selected from the required rotation speed N2 calculated in step 22 and the set rotation speed N□ determined according to the pilot pressure Pi, whichever is larger. Therefore, the controller 20 according to this embodiment includes a function generator 35 that outputs a set rotation speed N1 according to the pilot pressure Pi, and a maximum value selection circuit that selects the maximum value from the required rotation speed N and the set rotation speed N1. 36.

This embodiment is a modification of the second embodiment shown in FIG. 6, and since the lower limit of the target rotation speed N is determined by the set rotation speed N1 determined by the pilot pressure Pi, good operability and fuel efficiency can be achieved. Improved performance and reduced noise can be achieved.

G0 Effect of the Invention According to the present invention, the constant pump discharge flow rate line determined by the required flow rate according to the operation of the operating member and the constant horsepower curve of the prime mover controlled by the torque regulator intersect at the detected load pressure point. Since the prime mover rotation speed is controlled by
A desired flow rate can always be obtained within the capacity range of the engine and pump, fuel consumption rate can be improved, and noise can be reduced.

[Brief explanation of drawings]

Fig. 2 is a detailed block diagram of the controller, Fig. 3 is a P-q diagram, Fig. 4 is a P-Q diagram, and Fig. 5 is a detailed block diagram of the controller.
The figure is an engine characteristic IIA diagram. 6 to 10 are block diagrams of the controllers of the second to sixth embodiments. 1 Prime mover 3 Pulse motor 5 Potentiometer 6 Variable displacement hydraulic pump 6a Torque regulator 7 Control valve 8 Actuator 9
Pump pressure sensor 10 Operation lever 11 Pilot valve 12° Pilot pressure sensor 13 Fuel lever 13a: Rotation speed setting device 14/selection switch 2o: Controller 21 Function generator 22: Required rotation speed calculator 23° switching device
24: Servo control section 25 Motor driver Fig. 1

Claims (1)

[Claims] 1) A variable displacement hydraulic pump driven by a prime mover, at least one actuator driven by pressure oil discharged from the hydraulic pump, and an absorption torque of the hydraulic pump to prevent the prime mover from stalling. a torque regulator that controls the output torque of the prime mover to be lower than the output torque of the prime mover by a predetermined value; and a control valve that controls the pressure oil from the hydraulic pump and drives the actuator according to the operation of an operating member. The prime mover rotation speed control device includes: a required flow rate detection means for detecting a required flow rate of the actuator in response to an operation of the operating member; a pressure detecting means for detecting a load pressure of the actuator; and a required flow rate of the actuator. calculating means for calculating the required rotational speed of the prime mover, which is a value such that a constant pump discharge flow rate line and a constant horsepower curve of the prime mover controlled by the torque regulator intersect at a load pressure point; 1. A prime mover rotation speed control device for hydraulic construction machinery, comprising: rotation speed control means for controlling the rotation speed to a required rotation speed. 2) The rotation speed of the hydraulic construction machine according to claim 1, wherein the rotation speed control means controls the rotation speed of the prime mover to the required rotation speed only when the required flow rate is equal to or higher than a predetermined value. Number control device. 3) A variable displacement hydraulic pump driven by a prime mover, at least one actuator driven by pressure oil discharged from the hydraulic pump, and an absorption torque of the hydraulic pump set to a predetermined value based on the prime mover output torque to prevent the prime mover from stalling. a torque regulator that controls the drive of the actuator by controlling pressure oil from the hydraulic pump in accordance with the operation of an operating member; and a rotation speed setting that sets a set rotation speed of the prime mover. A prime mover rotation speed control device for a hydraulic construction machine, comprising: a required flow rate detecting means for detecting a required flow rate of the actuator in response to an operation of the operating member; and a pressure detecting means for detecting a load pressure of the actuator. and a calculation means for calculating the required rotation speed of the prime mover, which is a value such that a constant pump discharge flow rate line determined by the required flow rate of the actuator and a constant horsepower curve of the prime mover controlled by the torque regulator intersect at a load pressure point. and a rotation speed control means for controlling the rotation speed of the prime mover to the larger of the required rotation speed and the set rotation speed set by the rotation speed setting means. Machine prime mover rotation speed control device. 4) A variable displacement hydraulic pump driven by a prime mover, at least one actuator driven by pressure oil discharged from the hydraulic pump, and an absorption torque of the hydraulic pump set to a predetermined value based on the prime mover output torque to prevent the prime mover from stalling. a torque regulator that controls the drive of the actuator by controlling pressure oil from the hydraulic pump in accordance with the operation of an operating member; and a rotation speed setting that sets a set rotation speed of the prime mover. A prime mover rotation speed control device for a hydraulic construction machine, comprising: a required flow rate detecting means for detecting a required flow rate of the actuator in response to an operation of the operating member; and a pressure detecting means for detecting a load pressure of the actuator. , calculation means for calculating the required rotation speed of the prime mover, which is a value such that a constant pump discharge flow rate line determined from the required flow rate of the actuator and a constant horsepower curve of the prime mover controlled by the torque regulator intersect at a load pressure point; , a rotation speed control means for controlling the rotation speed of the prime mover to a smaller value after a predetermined time when the difference between the required rotation speed and the set rotation speed set by the rotation speed setting means becomes a predetermined value or more; A prime mover rotation speed control device for hydraulic construction machinery, characterized by comprising: 5) The calculating means calculates the required rotation speed of the prime mover using the maximum discharge volume within the control range of the torque regulator.
A prime mover rotation speed control device for a hydraulic construction machine as described in 2.