JPH03149402A - Flow rate control device for hydraulic circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flow rate control device for a hydraulic circuit included in a construction machine such as a hydraulic excavator.

[Conventional technology]

FIG. 1 is an explanatory diagram illustrating a conventional flow rate control device for a hydraulic circuit. In this figure, l is an actuator that outputs an operation signal X, for example, an electric signal, which is proportional to the operation amount, and 2 is connected to the operation device 1, and 2 is connected to the actuator 1 to control the flow rate Q according to the flow rate command signal Q0 corresponding to the operation signal X. This is a flow rate control mechanism that discharges hydraulic pressure.

Such a flow control mechanism 2 is constituted by a constant displacement pump and a directional valve with a variable orifice, a directional valve without a variable orifice and a servo valve, or a directional valve and a variable displacement pump. In particular, when using a servo valve, the flow rate can be easily controlled using a servo amplifier and an electric/hydraulic servo valve. In addition, in order to control the flow rate with a directional valve with a variable orifice,
The spool position with a variable orifice may be controlled by an electric/hydraulic servo valve, or the directional control valve with a variable orifice may be of the hydraulic pilot type, and the pilot hydraulic pressure may be controlled by the electric/hydraulic pilot valve. A variable orifice may also be controlled. In this case, the flow rate command signal Q0 becomes a command signal for the orifice opening degree. Furthermore, when a variable displacement pump is used as the flow rate control mechanism 2, whether it is a swash plate bomb or a diagonal axis pump, the tilt angle control mechanism can be easily configured with an electric/hydraulic servo system as described above. . In this case, the flow rate command signal Q. is a command signal for controlling the tilting angle of the swash plate or oblique shaft of the variable displacement pump.

Further, in FIG. 1, numeral 3 represents a hydraulic actuator, for example, a hydraulic cylinder, and 4 schematically represents a load applied to the hydraulic cylinder 3. As shown in FIG.

In such a flow rate control device, the flow rate Q discharged from the flow rate control mechanism 2 is the flow rate command signal Q.

That is, it corresponds to the operation signal X, and the operating speed (2) of the hydraulic actuator such as the hydraulic cylinder 3 can be controlled in accordance with the operation signal X.

By the way, when it comes to construction machinery such as hydraulic excavators,
During heavy excavation work or rough finishing work, the operating speed of hydraulic actuators such as the hydraulic cylinder 3 is high, and the flow rate often requires a flow rate near the maximum flow rate (Qo.). On the other hand, during light excavation work such as finishing slopes, it is necessary to reduce the speed of the hydraulic actuator and control it with high precision.

Therefore, in general, the flow rate characteristics of the flow rate control device shown in FIG. 1 are as shown in FIG.
The flow rate gradient is set to be small in the range A up to I, and the it gradient is set to be large in the range B beyond that range. Then, range A is used for fine operation, and range B is used for rough operation, thereby controlling the flow rate, that is, the operating speed of the hydraulic actuator.

[Problem to be solved by the invention]

However, in the conventional IT control device configured in this way, if range A of the flow characteristics shown in Fig. 2 is set to a large value, fine controllability is excellent, but medium/high speed controllability of the hydraulic actuator deteriorates. If the range B is set too large, the fine operability may deteriorate. Therefore, depending on the working form of various machines, the optimal range A
, B are required, but for example, in a hydraulic excavator,
Since emphasis is placed on medium-heavy excavation work, there is a tendency to set range B large, and as a result, satisfactory fine operability is often not obtained.

The present invention has been made in view of the actual situation in the prior art, and its purpose is to improve the flow rate of a hydraulic circuit that can ensure both good mid- to high-speed controllability of a hydraulic actuator and good fine controllability. The purpose is to provide a control device.

[Means to solve the problem]

In order to achieve this object, the present invention provides a flow rate control device for a hydraulic circuit, which includes an operation device that outputs an operation signal, and a flow rate control mechanism that discharges hydraulic pressure at a flow rate according to a flow rate command signal that corresponds to the operation signal. A setting means for setting two different flow characteristics corresponding to the operation signal, a detection means for detecting a temporal change in the operation signal, between the operation device and the flow rate control mechanism; According to the detection result of the detection means, the f
Addition and '$i calculating means for gradually increasing or decreasing the command value of the L quantity command signal, and an output means for outputting the command value obtained by the addition/subtraction means to the flow rate control mechanism. be.

[For production]

The present invention is configured as described above, and the setting means of the output means has a flow rate characteristic suitable for work that requires increasing the operating speed of the hydraulic actuator, and a flow rate characteristic that is suitable for work that requires increasing the operating speed of the hydraulic actuator. Two different flow rate characteristics are set in advance, including a flow rate characteristic suitable for the work. Therefore, when the actuator is operated with the intention of increasing the operating speed of the hydraulic actuator, there is a large temporal change in the operation signal detected by the detection means of the output means, and this result Accordingly, the addition $i calculating means of the output means selects, for example, one flow rate characteristic set by the setting means, that is, a flow rate characteristic suitable for the work that requires reducing the operating speed of the hydraulic actuator, and another one. A calculation is performed to gradually increase the command value of the flow rate command signal so that it approaches the flow rate characteristics suitable for work that requires increasing the operating speed of the hydraulic actuator, and the command value increases sequentially. is given to the flow rate control mechanism as a flow rate command signal, the operating speed of the hydraulic actuator is increased, and good mid- to high-speed controllability of this hydraulic actuator can be ensured.

Furthermore, when the actuator is operated with the intention of reducing the operating speed of the hydraulic actuator, the temporal change in the operation signal detected by the detection means is small, and the output means The addition and subtraction means are set by the setting means, for example, from the other flow rate characteristic set by the setting means, that is, the flow rate characteristic suitable for the work that requires increasing the operating speed of the hydraulic actuator. The command value of the flow rate command signal is gradually decreased so as to approach one flow rate characteristic that has been determined, that is, the flow rate characteristic that requires a reduction in the operating speed of the hydraulic actuator, and this sequentially decreasing command value is the flow rate. The command signal is given to the flow rate control mechanism, and the operating speed of the hydraulic actuator is reduced, ensuring good fine controllability of the hydraulic actuator.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flow rate control device for a hydraulic circuit according to the present invention will be described below with reference to the drawings. FIG. 3 is an explanatory diagram showing one embodiment of the present invention, FIG. 4 is an explanatory diagram showing flow characteristics in this embodiment, and FIG. 5 is a flowchart showing the procedure of processing performed in this embodiment.

In the embodiment shown in FIG. 3, l is an exchanger and 2 is a flow rate control mechanism, which are the same as those described above. Reference numeral 5 denotes an output means provided between the operating device 1 and the flow rate control mechanism 2, which outputs a predetermined flow rate characteristic to a flow rate command signal Q0 according to the magnitude of a temporal change in the operating signal X outputted from the operating device 1.
It is output to the flow rate control mechanism 2 as . This output means 5 is
For example, it consists of a microcomputer. and,
This output means 5 includes an input device 6 such as an A/D converter, a storage device 7 for storing functions and programs, an output device 8 such as a D/A converter, and a central processing unit ( CPU) 9. The storage device 7 of the output means 5 described above stores 2 signals corresponding to the operation signal X of the operation device l.
It includes a first storage section 7a constituting a setting means for setting two different flow characteristics, and a second storage section 7b for storing calculation results in the CPU 9. And the first
The two flow characteristics set in the storage section 7a are, for example, the fourth
The characteristics QM (x) and QL (x) shown in the figure are the characteristics QN (X) is the flow rate characteristic where the range where the flow rate gradient is small is small, and the characteristic Qt (X) is the flow rate where the range where the flow rate gradient is small is the large flow rate. This is a characteristic feature.

The CPU 9 described above also includes a detection means for detecting a temporal change in the operation signal The addition and subtraction means are configured to gradually increase or decrease the command value of the flow rate command signal Q0 so that it approaches another flow rate characteristic. And this CPU9
By repeating the program every predetermined period, the amount of change in the input value of the operation signal X, that is, the difference ΔX can be detected. When this difference ΔX is less than a certain value (slow operation state a of controller 1), S=0 is output, and when the difference ΔX is larger than a certain value (sudden operation state of controller 1), S=1 is output. It has become.

The processing operation in this embodiment will be explained according to the flowchart shown in FIG.

If the operating device 1 is operated slowly, the CPU 9 determines that S=0 in the procedure and moves to procedure k.

In this hand Mik, the previous flow rate command signal Q0 stored in the second storage section 7h of the storage device 7 and the first
The flow rate characteristic QL shown in FIG. 4 stored in the storage unit 7a of is CP
The CPU 9 reads out the previous flow rate command signal Q.
It is determined whether 0 is the same as the flow rate characteristic QL shown in FIG.

If they are the same, steps m and n are reached, and QL (X)
QL obtained by is the flow rate command signal Q. The output is closed and the process returns to the beginning.

It should be noted that the current flow rate command signal QO ("QL") is stored in the second storage section 7b of the storage device 7 along with the processing of step m above.

Here, if the operating device 1 is suddenly operated, S=1, and the process proceeds from step 1 to step i. In this procedure i, the second
The previous flow rate command signal Q stored in the storage unit 7b.

The flow rate characteristic Q8 of FIG. 4 stored in the first storage section 7a of the storage device 7 is read out to the CPU 9, and the CPU 9 determines whether the previous flow rate command signal Q0 is the same as the flow rate characteristic Q, t of FIG. Please be judged. In this case, in the previous step, steps g, h,
k.

Since the previous flow rate command signal Q calculated using m, n, and o was QL, it is determined NO and the process moves to step j.

In this procedure j, the previous flow rate command signal Q is used. command value (Q
A predetermined increment ΔQ is added to t, ) to generate a new flow rate command signal Q. ("Q o + ΔQ) is performed, and this new flow rate command signal Q0 (=Q, +ΔQ) is stored in the second storage section 7b of the control device 7 as the current flow rate command signal Q.

This QO ("QO + ΔQ)" is stored as
is output to the flow rate control mechanism 2, and the process returns to the beginning. Note that step i
passes every predetermined period, so it acts as an integral element, and Qo gradually increases, and a new flow rate command signal Q0 every time it increases is stored in the second storage section 7b of the storage device 7.
The flow rate command signal Q0 gradually approaches the flow rate characteristic Qa shown in FIG. 4. Q,=
When it becomes Qi, Q is stored in the second storage section 7b of the storage device 7.
, =Q14 are stored, and the judgment in step i is satisfied, the process moves to step p, and the flow rate command signal Q0 having the flow rate characteristic Q is output to the flow rate control mechanism 2. From now on, the controller 1
While is suddenly operated and while this state is maintained, S=1, so steps g, h, i, p, n.

0 is repeated.

Then, when the operating device 1 is operated slowly from this state, S=O, and the procedure goes from step to step 1. The previous flow rate command signal Q.

and the fourth stored in the first storage section 7a of the storage device 7.
The flow rate characteristic QL shown in the figure is read out to the CPL 19, and this CPU
9 is the previous flow rate command signal Q. It is determined whether or not is the same as the flow rate characteristic QL shown in FIG. In this case, step p
Since the calculation was performed through
The previous Affl command signal Q is stored in the storage unit 7b.
0 is Q8, which is determined as NO, and moves to move @l. In this step 2, a predetermined increment ΔQ is calculated from the previous flow rate command signal Q0.
is subtracted, calculation is performed to obtain a new flow rate command signal Q0, and this new flow rate command signal Q0 (=Q0−
ΔQ) is the current flow rate command signal Q in the second storage section 7b of the storage device 7. Is this Qo a flow rate system? 11 is output to mechanism 2 and returns to the beginning. Note that since step l passes through every predetermined period, it acts as an integral element in the same way as in step j described above,
Gradually Q. decreases, and a new flow rate command signal Q is generated each time the decrease occurs. is the second storage section 7b of the storage device 7
This flow rate command signal Q0 gradually approaches the flow rate characteristic Q shown in FIG. 4. Qo
” When Q t is reached, Q.=Q is stored in the second storage unit 7b of the storage device 7, and the judgment on the procedure is satisfied and the process moves to step m, which has the flow rate characteristic Q. A flow rate command signal Q. is output to the flow rate control mechanism 2.

In the embodiment configured in this way, the operating device lfJ<
When the IN operation is performed, the CPU 9 calculates the characteristic Q shown in FIG. 4 according to the determination that S=O, and the 2i! corresponding to the characteristic Q is calculated. The L view command signal Q0 is the flow rate control mechanism 2.
Since the characteristic Q has a large range in which the flow rate gradient is small, good fine operability of the hydraulic actuator can be ensured.

Further, when the operating device 1 is suddenly operated, the CPU 9 calculates the characteristic Q shown in FIG. 4 based on the determination that S=1, and the flow rate command signal Q is calculated according to the characteristic Q8. but? Since the characteristic Q)l is outputted to the a quantity control mechanism 2 and the range where the II gradient is small is small, it is possible to ensure good mid-to-high speed controllability of the hydraulic actuator.

Then, the CPU 9 executes steps 11jjj, i, ff in FIG.
Since it has the addition and subtraction means shown in , the selection of the flow rate characteristic for sudden and slow operation of the operating device l is performed while changing sequentially so as to approach one of the flow rate characteristics as time changes. Better operability can be ensured.

In the above embodiment, only the positive portion of the flow rate characteristics is shown in order to simplify the explanation of PM, but it goes without saying that the negative portion also has characteristics.

(Effects of the Invention) Since the mgA controller of the hydraulic circuit of the present invention is configured as described above, it is possible to ensure both good mid-to-high speed controllability and good fine controllability of the hydraulic actuator. ,
In addition, it is possible to smoothly transition between medium-to-high reach control and fine operation control, and there is an effect that the operation driven by the hydraulic actuator can be performed optimally for operations such as st.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram illustrating a conventional hydraulic circuit flow g and li control device, Fig. 2 is an explanatory diagram showing characteristics of the flow rate control device shown in Fig. 1, and Fig. 3 is a hydraulic circuit of the present invention. FIG. 4 is an explanatory diagram showing an embodiment of the flow rate sit device shown in FIG. 4, FIG. 4 is an explanatory diagram showing flow characteristics in the embodiment shown in FIG. 3, and FIG. l...Manufacturer, 2...Flow rate control mechanism, 5...Output means, 6...Output device, 7...Storage device, 7a...
・First storage unit (setting means), 7b...Second storage unit, 8...Output device, 9...-CPU (detection means, addition, subtraction means) Go to Figure 1 3 v-4 17 desired] 1 X=Qnl I Q-Koichi---T

Claims (1)

[Claims] (1) A flow rate control device for a hydraulic circuit comprising an operating device that outputs an operating signal, and a flow control mechanism that discharges pressure oil at a flow rate according to a flow rate command signal corresponding to the operating signal, wherein the operating device and the above-mentioned A setting means for setting two different flow characteristics corresponding to the operation signal, and a detection means for detecting a temporal change in the operation signal, between the flow control mechanism and the operation signal.
Addition that gradually increases or decreases the command value of the flow rate command signal so that one flow rate characteristic set by the setting means approaches another flow rate characteristic set according to the detection result of the detection means; 1. A flow rate control device for a hydraulic circuit, comprising: a subtraction means, and an output means for outputting a command value determined by the addition and subtraction means to the flow rate control mechanism.