JPH01178624A - Excavator - Google Patents

Abstract

PURPOSE:To use energy efficiently by limiting a time variation of the target of pressure oil necessary for operating a turning motor according to controlling quantities of control levers and adjusting the discharge of a pump. CONSTITUTION:A first operation circuit 20 calculates the maximum discharge (q)smax of a hydraulic pump from a boom arm and controlling quantities lB, lA and lS of each of control levers 14, 15 and 16. A second operation circuit 21 calculates the target flow (Q)S of pressure oil necessary for operating a hydraulic motor only a portion equivalent to the controlling quantity of the control lever 16. A third operation circuit 22 limits the increment of a time variation (Q')S of pressure oil against a hydraulic turning motor 17 and outputs. An incremental flow value (q)S with the limited maximum value is integrated by an integrating circuit 23, and an integral value (Q)SI is outputted into a pump 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an excavator that performs excavation work by displacing the position of the tip of the working machine such as an arm or a boom.

[Conventional technology]

As we all know, excavators work with arms, booms, etc.
The position of the machine is fr tf = a! Supply to the corresponding hydraulic cylinder, control the amount of pressurized oil according to the amount of operation of the control lever corresponding to the machine to displace it, and furthermore change the direction of each work machine by the hydraulic motor for swing, - One
- configured to carry out the required excavation operations thereby;

FIG. 6 is a block diagram showing an outline of the control system of such an excavator. Hydraulic cylinders 3 and 4 are installed to displace the boom 1 and the arm 2, and the boom 1 and the arm 2 are A turning hydraulic motor 17 is provided to simultaneously turn the two on a horizontal plane. In addition, hydraulic cylinders 3 and 4
Operation valves 5.6 and 7.8 are provided to control the flow rate of pressure oil input to the swing hydraulic motor 17, and an operation valve 9 is provided to control the flow rate of pressure oil input to the swing hydraulic motor 17. , pressure oil from two variable displacement hydraulic pumps 10.11 is input in parallel to each of the operation valves 5-9. The hydraulic pump 10.11 is driven by the engine 12 and its discharge flow ff1QP1. QP2 is controlled by the pump control system (pcs) of the hydraulic control device 13. On the other hand, the discharge flow rates of the operating valves 5 to 9 are controlled by the operating valve control signal VC8 of the hydraulic control device 13.

The hydraulic control device 13 is connected to the boom 1. Arm 2. The opening degrees of the control valves 5 to 9 and the hydraulic pump 1 are adjusted according to the amount of operation of the control levers 14 to 16 corresponding to the swing hydraulic motor 17, respectively.
It outputs the control signals vcs and pcs that control the swash plate angle of 0.11, and the flow rate of pressure oil to the hydraulic cylinder 3.4 and the discharge flow of the hydraulic pump 10. ff1QP1. By controlling QP2, boom 1. While displacing arm 2 according to the amount of operation of operation valves 14 and 15, these booms 1.
The arm 2 is turned on a horizontal plane according to the amount of operation of a turning control lever 16.

Such a boom 1. The displacement and horizontal pivoting movement of the arm 2 allows the required excavation work.

(Problem to be Solved by the Invention) However, in the excavator as described above, when the boom 1 and the arm 2 are rotated independently, or when the boom 1
Conventionally, when performing a turning operation while lowering the tip of the
Operation amount j of the turning control lever 16 in Figure (a)! s, 7th
The discharge pressure pp1 of the hydraulic pump 10 in Figure (b), Figure 7 (
As shown in the time change characteristic of the discharge flow fik QPl of the hydraulic pump 10 in C), the discharge flow rate QP1 of the hydraulic pump 10
is simply controlled in a proportional relationship in response to the operations ffi and l of the turning control lever 16. However, the swinging operation has high inertia because the weights of the boom 1 and arm 2 are large. For this reason, it takes time for the turning speed to reach a steady speed, and as shown in the shaded area in FIG. 7(C), the discharge flow rate QP
There was a problem in that the number of numerals 1 was larger than that of 1, and the energy loss of the pressure oil was large.

An object of the present invention is to provide an excavator that can efficiently use the energy of pressure oil.

[Means for Solving the Problems] The present invention provides a first means for calculating a target value of the amount of pressure oil necessary to operate a swing hydraulic motor in accordance with the operation amount of a swing control lever; a second means for limiting the temporal change amount of the target value calculated by the first means according to the amount of operation of the entire work equipment control lever; and a second means for integrating the target value corrected by the second means. The above object is achieved by providing in the hydraulic control device a third means for controlling the pressure oil discharge flow rate of the variable displacement hydraulic pump in accordance with the integral value.

(Function) The amount of change over time in the target value of the amount of pressure oil required to operate the swing hydraulic motor is limited by the second means in accordance with the amount of operation of the entire control lever for a working machine such as a boom, The discharge flow rate of the hydraulic pump is controlled according to the integral value of the limited target value. That is, the amount of pressurized oil applied to the hydraulic motor during turning is controlled so that its temporal change Q is limited and gradually increases as the speed approaches the steady speed. Therefore, the pressure oil energy discharged from the hydraulic pump can be used efficiently.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of a hydraulic control device which is the main part of the present invention, and only the sub-systems of the hydraulic pump 10 shown in FIG. 6 are illustrated here. In the figure, boom 1. Signal 11 representing operation O of control lever 14.1.5° 16 of arm 2 and swing hydraulic motor 17
! Eight, j! S is the maximum discharge flow rate qS of the hydraulic pump 10
It is input to the first arithmetic circuit 20 which calculates IIlax.

Further, the output signal 1 of the turning control lever 16 is input to a second sieve circuit 21 that calculates a target value QS of the amount of pressure oil required by the turning hydraulic motor 17.

The first arithmetic circuit 20 receives the signal 1. When iA,,li are input, qsIIlax=fs (j!B, j!A
, j! S) - According to the relational expression (1), the boom hydraulic cylinder 3 is adjusted by the amount of operation of each control lever 14 to 16.
．． Maximum discharge flow 1 of the hydraulic pump 10 necessary to operate the arm hydraulic cylinder 4 and the swing hydraulic motor 17
Calculate q sn+ax. In addition, the second calculation circuit 21 calculates the operation amount of the turning control lever 16 [jl
It is calculated using the characteristic curve of S and QS.

This maximum discharge flow fi1 q smax and target flow ff1Q
The value of s is input to the third arithmetic circuit 22.

The third arithmetic circuit 22 outputs the incremental flow ff1qs per time of Q'=dQS/dt, but when the maximum discharge flow mqSlaX calculated by the first arithmetic circuit 20 is input, this qsmax The maximum value of the incremental flow ff1Qs is limited to the same value as qsn+ax and output.

That is, the incremental value of the time change ff1Qs' of the pressure oil for the swing hydraulic motor 17 is outputted while being limited by qSmaX.

The incremental flow rate value qS whose maximum value is thus limited is integrated by the integrating circuit 23. Then, the integral 1-direction QSI=Σ
qsdt is output as a signal for controlling the swash plate angle of the hydraulic pump 10. Thereby, the discharge flow rate QP1 of the hydraulic pump 10 is controlled so that QP1=QSI.

In this way, instead of simply securing the amount of pressure oil required by the hydraulic motor 17 in proportion to the amount of operation of the control lever 16,
By limiting the required temporal change amount of pressure oil 0 and limiting the discharge flow rate of the hydraulic pump 10 by the integral value of the limited temporal change amount, the discharge flow rate 11kQP1 of the hydraulic pump 10 becomes the second As shown in Figure (C), the flow rate increases gradually, and reaches a flow rate corresponding to the amount of operation of the control lever 16 near when the swing hydraulic motor 17 reaches a steady speed. Therefore, the energy of the pressure oil output from the hydraulic pump 10 can be effectively utilized. In addition, FIG. 2(a) shows the operation of the control lever 16 ff1J! S, FIG. 2(b) shows the discharge pressure PP1 of the hydraulic pump 10.

FIG. 3 is a block diagram of a hydraulic side tIl device showing another embodiment of the present invention. This embodiment is designed to prevent the operating speeds of the boom and arm from mismatching when the turning operation and the lifting and lowering operations of the boom and arm are performed simultaneously. That is, the discharge flow rate QPI of the hydraulic pump 10 is determined by the operation amount of each control lever 14 to 16, fiB, J
! Assume that the change is made as shown in FIG. 4 (,a) according to All5. At this time, the operation valve 5 that controls the amount of pressure oil to the boom hydraulic cylinder 3, the operation valve 7 that controls the amount of pressure oil to the arm hydraulic cylinder 2, and the operation valve that controls the amount of pressure oil to the hydraulic motor 17. 9 opening degree is V! l, V 7. V9
As shown in FIG. 4(b), it is assumed that the control levers 14 to 16 are held constant after the operation starts. Then, the actual pressure oil i used by the hydraulic motor 17 when turning is shown in Fig. 4(a).
Since the change is like a dashed line, the control lever 14~
Immediately after the start of operation 16, the operating valves 5, 7.9 are a little constricted compared to the discharge flow ff1QP1 outputted by the hydraulic pump 10, and when the rotation speed approaches the steady speed, they are a little open, and the operating valves 5, 7. The differential pressure at the pressure oil inlet and outlet of .9 is ΔPV
5゜△P V7. ΔPV9 is as shown in FIG. 4(C). As described above, when the differential pressure between the operating valves 5° and 7.9 changes with the passage of time during the swinging operation, the boom 1. Depending on the magnitude of the load on arm 2, the operating speeds of boom 1 and arm 2 will not match, which is undesirable for work.

This embodiment solves this problem, and as shown in FIGS. 5(a) to 5(C), the discharge flow ΦG of the hydraulic pump is
) P1 each operation valve 5. ．． 7.9 opening degree V5゜■7. V9,
Differential pressure ΔPV5. ΔPV7. It is designed to control ΔPV9.

In FIG. 3, the circuits 20 to 23 are 1-1.
n - This is the same as the embodiment shown in the figure, but here the following are newly added, and the opening degrees V5 and V7 of the operation valves 5 and 7.9 are changed.
, V9 etc., the discharge flow rate QP1 of the hydraulic pump 10 is controlled.

That is, the signals jB and j2A representing the amount of operation of the control lever 14.15 are sent to the fourth arithmetic circuit 24. It is input to the fifth arithmetic circuit 25. Fourth
The arithmetic circuit 24 receives a signal representing the amount of operation of the control lever 14;
When ffB is input, the target value QB of the amount of pressure oil required to operate the boom 1 only by the signal indicated by ffB.
is set to 0 using the characteristic curves of uB and QB. Similarly, when a signal IA representing the operation amount of the control lever 15 is input to the fifth calculation circuit 25, the signal IA representing the operation amount of the control lever 15 is inputted to the fifth calculation circuit 25.
Target value of the amount of pressure oil required to operate arm 2 Q^
(Which characteristics of l and QA) are expressed using J-b.

These target values QB and QA are manually inputted to the addition circuit 26 along with the target value QSI of the amount of pressure oil required by the hydraulic pump 10 outputted from the integrating circuit 23, and the sum thereof is determined.

The total value QP is determined by the limiter circuit 27 as the maximum rated flow rate Qma determined by the physical conditions of the hydraulic pump 10 itself.
After being limited by χ, it is output as a signal QP' that controls the swash plate angle of the hydraulic pump 10.

As a result, the discharge flow ff1Qp1 of the hydraulic pump 10 is controlled in accordance with the summation value QP determined by the addition circuit 26 while the maximum rated capacity of the hydraulic pump 10 is within the range.

On the other hand, boom 1. The values of the target flows iQB and QA of the pressure oil necessary to operate the A-1\2 and the value of the flow rate QSI to be discharged from the hydraulic pump 1 are determined by the distribution circuit 28 through the operation valve 5.
7.9 is distributed to control circuits 29 to 31 that control the opening degree.

Therefore, the control circuit 29 uses the target opening degree value ASI of the operation valve 9.
QSI, , ffS , JOB , J2A's function ASI= fsI (081,)S, , flB, , 1.
8), and the opening degree V9 of the operation valve 9 is controlled by this target opening value ASI.

Similarly, the control circuit 30 sets the value AB of the target opening of the operation valve 5 to QBI! Function AB=fB (
QB, Is, IF3.18), and the opening V5 of the operation valve 5 is controlled by this target opening value AB.

Furthermore, the control circuit 31 sets the target opening degree value A8 of the operating valve 7 to QA, f! To function A to S,,LB,,12 -f^
(QA,,es,,1.1A), and the opening of the operation valve 7 is determined by this target opening value AA.
Control 7.

Therefore, the opening degree V9 of the operating valve 9 corresponding to the hydraulic motor 17
changes over time in the same manner as the target value QSI of the discharge flow rate of the hydraulic pump 10, as shown in FIG. 5(b). That is, the opening degree V9 of the operation valve 9 gradually increases as the turning speed increases, and becomes constant near the steady speed. On the other hand, the opening degrees V5 and V9 of the operating valves 5°7 are as shown in Fig. 5(b) at the start of the turn, as a result of the amount of pressure oil distributed to the hydraulic cylinders 3 and 4 increasing at the start of the turn. It starts to open slightly, and becomes constant as the turning speed approaches the steady speed.

By controlling the opening degree of the operation valve 5.7.9 by 1tilJ in this way, it is possible to prevent the pressure indication input to the hydraulic cylinder 3゜4 from becoming excessive or insufficient depending on the rotation speed. , boom 1 and arm 2 can be matched to operate.

Note that the operation valves 6 and 8 are also controlled in the same manner as 5 and 8.

(Effects of the Invention) As explained above, in the present invention, the amount of change over time in the amount of pressure oil for the swing hydraulic motor is limited during swing, so that the pressure oil energy discharged from the hydraulic pump can be efficiently used. can be used.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing its operation, and Fig. 2 shows the operation amount of the control lever, and time changes in the discharge pressure and discharge flow rate of the hydraulic pump. FIG. 3 is a block diagram showing another embodiment of the present invention. FIG. 4 is a block diagram showing another embodiment of the present invention.
The figure is a characteristic diagram showing the time change of the operating valve opening degree and the operating valve differential pressure to explain the problem when the swing operation is performed at the same time as the work operation of the boom, etc., and Fig. 5 is an example of the embodiment of Fig. 3. To,
Figure 6 shows the schematic configuration of the control system of a conventional excavator. The block diagram, FIG. 7, is a characteristic diagram for explaining the problems of the configuration of FIG. 6. DESCRIPTION OF SYMBOLS 1... Boom, 2... Arm, 3, 4... Hydraulic cylinder, 5-9... Control valve, 10.11... Variable displacement hydraulic pump, 12... Engine, 13. ...Hydraulic control device, 14-16... Control lever, 17... Hydraulic motor for turning, 20... First calculation circuit, 21...
2nd arithmetic circuit, 22...3rd arithmetic circuit, 23...integrator circuit, 24...4th arithmetic circuit, 25...5th arithmetic circuit, 26...addition circuit, 27...・Limiter circuit,
28... Distribution circuit, 29-31... Control circuit. Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] A plurality of hydraulic cylinders respectively corresponding to a plurality of working machines that displace the position of the tip of a working machine, an operation valve corresponding to the hydraulic cylinder that controls the flow rate of pressure oil to each of these hydraulic cylinders, Pressure oil is supplied in parallel to a swing hydraulic motor that swings the work equipment, an operating valve that controls the flow rate of pressure oil to the swing hydraulic motor, an operating valve corresponding to the hydraulic cylinder, and an operating valve corresponding to the swing hydraulic motor. a variable displacement hydraulic pump, and a hydraulic control device that controls the pressure oil discharge flow rate of the hydraulic pump and the opening degree of each of the operation valves according to the operation amount of a swing control lever and a work equipment control lever. In an excavator, a first means for calculating a target value of the amount of pressure oil necessary to operate a swing hydraulic motor in accordance with the operation amount of a swing control lever; a second means for limiting the amount of change over time in the target value according to the amount of operation of the entire work equipment control lever; and a second means for integrating the target value corrected by the second means, An excavator characterized in that the hydraulic control device is provided with a third means for controlling a pressure oil discharge flow rate of a variable displacement hydraulic pump.