JPS6239295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a variable displacement hydraulic pump connected to actuator means driven by the pump, the operating speed of the actuator means being dependent on the position of the variable displacement member of the pump. The present invention relates to a control device for a hydraulic circuit to be controlled, and particularly to a control device for a hydraulic circuit that controls the acceleration of an actuator means by limiting the operating speed of a variable displacement member of the pump to a predetermined maximum speed or less. .

The above hydraulic circuit, which is formed by connecting a variable displacement hydraulic pump and an actuator driven by the pump, is used, for example, in civil engineering and construction machines such as hydraulic excavators and hydraulic cranes, and in hydraulic excavators for coal mining. It is proposed that. In this case, for example, in a hydraulic excavator, work members such as a boom, an arm, a bucket, a traveling body, and a revolving body are driven by a hydraulic cylinder, a hydraulic motor, and the like that constitute the actuator of the hydraulic circuit device. In such a hydraulic circuit, the operating speed of the actuator is determined by the displacement of the pump, so for example, when the boom starts operating, the variable displacement member or swash plate of the pump connected to the boom cylinder is rapidly operated to increase the displacement. If the value is increased rapidly, the boom cylinder will be moved suddenly, causing a large shock. The same is true during deceleration; if the displacement of the hydraulic pump is suddenly reduced, a large shock may occur and the vehicle may become uncontrollable. Furthermore, when the vehicle is running, the driver is shaken by the shock at the start, causing the control lever to move, resulting in a hunting phenomenon occurring through the driver.

In order to solve the above-mentioned problems, a control method for controlling the variable displacement member or swash plate of a variable displacement pump while limiting its operating speed to a preset maximum speed or less is proposed, for example, as disclosed in Japanese Patent Application Laid-Open No. 1986-
This is proposed in Publication No. 59006.

As described above, in the hydraulic circuit, the operating speed of the actuator is determined by the displacement of the variable displacement hydraulic pump, and the displacement is determined by the position of the variable displacement member.
The variable displacement member is a swash plate in a swash plate pump. Therefore, in a hydraulic circuit using a swash plate pump, the operating speed of the actuator is determined by the position of the swash plate, and the acceleration of the actuator is controlled by changing the operating speed of the swash plate.

In the conventional control method described above, when an operation signal indicating a position command value of the swash plate is outputted by the operation lever, the increasing speed or decreasing speed of the position command value is compared with a preset maximum speed. As a result, if the change rate of the position command value is larger than the set maximum speed, the set maximum speed is applied, and if it is smaller than the set maximum speed, the position command value is increased or decreased, and the swash plate position is It is output to the swash plate drive device while being compared with the output of the displacement meter for detection. Thus, the swash plate of the variable displacement hydraulic pump is controlled to move its position to the position commanded by the operating lever while limiting its operating speed to below the set maximum speed. With this configuration, by setting the set maximum speed to a value suitable for the work member driven by each actuator, it is possible to perform a smooth operation without a shock. This is called actuator acceleration control or swash plate speed control.

By the way, the set maximum speed is a constant value for each work member, and the maximum speed must be set small for work members that have large inertia, such as booms and traveling bodies. Therefore, even if an attempt is made to stop a work member with a small set maximum speed, the work member will not suddenly stop. For example, it is very dangerous when you have to stop suddenly while driving. Furthermore, it becomes difficult to accurately stop the work member at a target position or to suddenly reverse the direction of movement of the work member.

Further, the set maximum speed is usually set at a constant value that prevents the movement of the actuator from slowing down and causes less shock when the operating lever is suddenly operated from the neutral position to the full extent. Therefore, the set maximum speed is too large when the amount of operation of the operating lever is small, that is, when the operating speed of the hydraulic actuator is small and delicate operation is desired where even the slightest shock can be a problem. Therefore, if the operating lever is rapidly moved even during such minute operations, the actuator will move at the set maximum speed, resulting in a shock. Furthermore, even during normal operation, the pressure at the beginning of actuator movement is affected by the swash plate speed, so in conventional control methods, a peak pressure occurs at the beginning of actuator movement.
Shock wakes up.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to enable an actuator to operate smoothly without sluggishness and with less shock during normal operation.
When positioning the load on the actuator or suddenly reversing the operating direction of the actuator, the actuator can be operated quickly, and furthermore, the actuator can be operated with almost no shock when starting the actuator or making small operations. It is an object of the present invention to provide a control device for a hydraulic circuit that can perform the following steps.

Another object of the present invention is to obtain actuator operation quickly and with less shock during emergency stop of the actuator, load positioning of the actuator, and reversal operation of the actuator, and furthermore, when the actuator operates at high speed, delicate actuator operation can be obtained. An object of the present invention is to provide a control device for a hydraulic circuit that can easily adjust speed.

In order to achieve the above object, according to the present invention, a variable displacement hydraulic pump and an actuator means driven by the pump are connected, and the operating speed of the actuator means is controlled by the displacement variable member of the pump. a control device for a position-controlled hydraulic circuit, the operating device generating an operating signal for commanding the position of the variable displacement member of the pump and thus commanding the speed of operation of the actuator means; a detection device that generates a detection signal indicating the actual position of the variable volume member;
A control device for a hydraulic circuit comprising: a pump control device that controls the variable displacement member while limiting its operating speed to a set maximum speed or less based on the operation signal and the detection signal, Regarding the speed, a first set maximum speed and a second set maximum speed larger than the first set maximum speed are set in advance, and the operating direction of the actuator means commanded by the operation signal and its actual speed are set in advance. The first set maximum speed is selected when the operating directions are equal, and when the displacement variable member is not in the actual neutral position and the operation signal indicates the neutral position of the displacement variable member, or a maximum speed setting device for selecting the second maximum speed setting when the direction of movement of the actuator commanded by the operation signal is opposite to its actual direction of movement; the pump control device selects the second maximum speed setting; The device is configured to control the speed of the displacement variable member based on a first or second set maximum speed selected by the device, and the maximum speed setting device generates the first set maximum speed. and second means for generating the second set maximum speed,
The set maximum speed is in a functional relationship with the operation signal such that its absolute value increases as the operation signal changes to move the displacement variable member away from its neutral position, and the second setting The absolute value of the maximum velocity increases as the operation signal changes to cause the displacement variable member to move from one of its normal and reverse maximum positions to the neutral position, and the operation signal increases the displacement variable member. There is provided a control device characterized in that when the variable member is changed to operate from near the neutral position to the other maximum position, the control device has a functional relationship with the operation signal such that the absolute value becomes larger. be done.

Preferred embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a hydraulic circuit is indicated generally by the reference numeral 2, and includes a variable displacement hydraulic pump 4 and a hydraulic motor or actuator 6 driven by the pump 4 connected in a closed circuit. It has been made. In this embodiment, the pump 4 is a swash plate pump, and the swash plate 8 constitutes a variable displacement member. The angle or position of the swash plate 8 is varied by a drive device 10. The pump 4 drives the actuator 6 with a displacement corresponding to the position of the swash plate 8. That is, the operating speed of the actuator 6 is determined by the position of the swash plate 8 and can be increased or decreased by changing the position of the swash plate 8. Furthermore, the acceleration or deceleration of the actuator 6 is determined by the operating speed of the swash plate 8.

The swash plate drive device 10 may be any servo valve mechanism capable of driving the swash plate 8 to a position in response to an input signal, and may be any servo valve mechanism capable of driving the swash plate 8 to a position according to an input signal,
The structure shown in FIG. 3 of Publication No. 01031 can be used.

Note that in order to simplify the configuration of the hydraulic circuit in FIG. 1, attached members such as a brushing valve are omitted.

The hydraulic circuit 2 is controlled by a control device 160, which is an embodiment of the present invention. The control device 160 is
An operating lever 14 that is an operating device that indicates the position of the swash plate 8 and the operating direction and speed of the actuator 6; and a displacement meter 16 that detects the position of the swash plate 8.
and the output signal of the operating lever 14, that is, the operating signal X _L
and the output signal of the displacement meter 16, that is, the swash plate position signal Y _L
input, and input the maximum speed setting circuit 162 which instructs the maximum value of the operating speed of the swash plate 8, the operation signal X _L , the swash plate position signal Y _L , and the output signal of the circuit 162, that is, the maximum speed signal α. , a pump control circuit 1 that generates an output signal Z for driving the drive device 10.
64.

The maximum speed setting circuit 162 sets first, second and third set maximum speeds α ₁ , corresponding to the operation signal _XL .
First, second, and third set maximum speed generation circuits 166, 16 that generate α ₂ and α ₃ signals, respectively.
8 and 170, and determine the swash plate position signal Y _L and find that Y _L ≧
a comparator 172 that inputs a “1” signal when Y _{L is 0 and outputs a “0” signal when Y L} <0;
Compare the swash plate position signal Y _L and _the operation signal X _L
Comparator 174 outputs a “1” signal if ≧Y _L and outputs a “0” signal if X _L <Y _L
and an exclusive OR (EXOR) circuit 176 which outputs a "0" signal if the outputs of the comparators 172 and 174 are the same, and outputs a "1" signal if they are different.
When the output of the EXOR circuit 176 is "1", the switch 1 is switched to the b terminal side, and when it is "0", the switch 1 is switched to the a terminal side.
78, and a switch 180 which switches to the b terminal side when the output of the comparator 172 is "1" and switches to the a terminal side when the output is "0".

The relationship between the operation signal _XL in the first set maximum speed generation circuit 166 and the first set maximum speed _α1 is a function as shown in FIG. That is, in the range where the operation signal X _L is positive, X _L becomes X _L1
= 1/4X When X _Lnax is less than X _L1 , α ₁ becomes the minimum value α ₁₁ , and when X _L exceeds X _L1 , α ₁ gives α ₁₁ a value that increases in proportion to the increase in X _L. When X _L reaches a predetermined value close to the maximum manipulated variable X _Lnax , α ₁ becomes the maximum α ₁₂ . Further, when the operation signal _XL is in the negative range, α ₁ becomes the inverted value of α ₁ in the positive range. _α11 is a value that does not cause a shock to the actuator during fine operation or activation of the actuator, and _α12 is a value that does not cause the actuator to move slowly when the operating lever is fully operated from the neutral position.

The relationship between the operation signal _XL in the second set maximum speed generation circuit 168 and the second set maximum speed _α2 is a function as shown in FIG. That is, α ₂ is always in the positive range, and when the operation signal _XL is at or near the negative maximum operation amount −X _Lnax , α ₂ becomes the minimum value α ₂₁ , and as _XL increases from there, Then α ₁ increases almost linearly and
When _L enters a predetermined range close to zero, α ₂ becomes an intermediate value α ₂₂ , and when X _L exceeds the lower limit X _La of the dead zone of the pump control circuit, which will be described later, α ₂ becomes the maximum value α
It becomes ₂₃ . In addition, the third set maximum speed generation circuit 17
Operation signal X _L at 0 and third set maximum speed α
₃ , as shown in FIG. 4, is a functional relationship that is the inversion of the relationship between X _L and α ₂ shown in FIG. That is, α ₃ is always in the negative range, and when the operation signal X _L is at or near the maximum positive operation amount X _Lnax , α ₃ has the minimum absolute value α ₃₁ ,
As X _L decreases from there, the absolute value of α ₃ increases almost linearly, and when X _L enters a predetermined range close to zero, α ₃ takes an intermediate value α ₃₂ and K _L
When becomes equal to or less than the upper limit X _Lb of the dead zone of the pump control circuit, which will be described later, α ₃ becomes α ₃₃ , which has the maximum absolute value.

In the second set maximum speed generation circuit 168,
α ₂₁ causes the actuator to receive shock when the operating lever is at or near the negative maximum operating amount position and when the operating lever is returned a little to make a delicate speed adjustment, or when the operating lever is returned to a large extent at the beginning of deceleration. This is a value that does not occur. α ₃₁ in the third set maximum speed generation circuit 170 has a value similar to α ₂₁ when the operating lever is at or near the positive maximum operation amount position. In the second set maximum speed generation circuit 168, α ₂₃ is used to rapidly decelerate the actuator during an emergency stop when the operation lever is in the negative operation amount range, when positioning the actuator load, or during reverse operation. It is a value that can be
α ₃₃ in the third set maximum speed generation circuit 170
is when the operating lever is in the positive operating amount range.
The value is similar to _α23 . Therefore α ₂₃ and |α ₃₃ |
is set to a value larger than the maximum value α ₁₂ in the first set maximum speed generation circuit 166.

As shown in FIG. 5, the pump control circuit 164 includes an adder 180 that subtracts the swash plate position signal Y _L from the operation signal X _L , and a deviation signal ΔX that is the output of the adder.
a differentiator 182 that differentiates and converts it into the amount of change △X with respect to time, an absolute value circuit 184 that converts △X into its absolute value |△X Absolute value circuit 18 for converting into |α|
6, |△X〓| and |α|, and enter |△X〓|≧
When |α|, it outputs a “0” signal and switches switch 1.
A comparator 192 switches the switch 90 to the b terminal side, outputs a "1" signal when |△X〓|<|α|, and switches the switch 190 to the a terminal side, and amplifies the output signal of the switch 190 to control the pump. and an amplifier 194 that outputs a signal Z. △X〓 is sent to the a terminal of the switch 190, and α is sent to the b terminal.
will be sent. Therefore, when |△X〓|<|α|, the switch 190 is switched to terminal a and a signal Z based on △X is generated, and when |△X〓|≧|α|, the switch 190 is switched to terminal b. A signal Z based on α is generated.

The pump control circuit 164 also controls the operation lever 14.
To prevent the actuator from making unnecessary movements due to slight movements near the neutral position of the
_L has a dead zone in which the pump control signal Z becomes zero between X _La and X _Lb in FIGS. 2 to 4.

The operation of the above control device 160 will be explained with reference to the timing chart shown in FIG.

In FIG. 6, t ₀ indicates a time point when both the operation signal X _L and the swash plate position signal Y _L are zero. From this point until t ₁ , _move the operating lever 14 to
If the operation is suddenly performed to
Since _L ≧0, “1” is output. Furthermore, since the swash plate position changes later than the change in the operation signal due to the speed control of the pump control circuit 164, X _L ≧
_YL , and the comparator 174 outputs "1". Therefore, since both inputs of the EXOR circuit 176 are "1", it outputs "0" and the switch 17
8 to the a terminal side. As a result, the first set maximum speed generating circuit 166 having the function shown in FIG. 2 is selected. Therefore, the maximum speed setting circuit 162 outputs α 11 to α 12 as the set maximum speed between t _{0 and} t ₁ , and then outputs α ₁₂ from t ₁ to t ₂ , and the pump control circuit 164 outputs α ₁₁ to α 12 as the set maximum speed. A signal Z is output to the drive device 10 so that the swash plate moves at a speed less than this set maximum speed, and the swash plate position is changed to Y _Ln corresponding to the operation signal X _Lnax .
Move to _ax . Therefore, from t ₀ to t ₂ , the swash plate 8 initially moves at a slow speed of α ₁₂ or less, and after approximately t ₁ it moves at a normal speed of α ₁₂ . Therefore, it is possible to start the actuator without causing a shock and to operate the actuator without slowness.

Next, if the operating lever 14 is suddenly returned to the neutral position between time t ₃ and time t ₄ in FIG. 6, the output of the comparator 172 in FIG. 1 remains "1" since Y _L ≧0. However, the pump control circuit 164
Due to the speed control of the swash plate, X _L <Y _L and the output of the comparator 174 becomes "0". Therefore, the inputs of the EXOR circuit 176 become "1" and "0", and the output becomes "1". Therefore, switch 178
is switched to the b terminal side. At this time, comparator 1
Since the output of 72 is "1", the switch 180 is switched to the b terminal side. As a result, the third set maximum speed generating circuit 170 shown in FIG. 4 is selected. Therefore, between t ₃ and t ₅ in FIG. 6, the circuit 162 operates at the set maximum speed from α ₃₁ to _{α 32 in FIG} . Once in, it outputs α ₃₃ and the pump control circuit 164 returns the swash plate 8 to the neutral position according to its set maximum speed. Therefore, at _the initial stage of operation immediately after t ₃ , the swash plate 8 moves at a slow speed of α ₃₁ to α ₃₂ and can decelerate the actuator with less _shock . α
It moves at a fast speed of _{33 degrees} and can quickly stop the actuator during emergency stops, load positioning, etc. Alternatively, for example, without returning the operating lever to the neutral position, return it a small amount to around X _L0 in Fig. 4,
When you want to make subtle speed adjustments to the actuator, _α31 is output as the maximum set speed. Therefore, the swash plate 8 moves at a gentle speed of α ₃₁ , making it possible to easily make delicate speed adjustments of the actuator.

Next, as shown in FIG. ₆ from t6 to _t7 , the operating lever is operated to the position X _L1 . At that time, as in the case from t ₀ to t ₂ , since _{Y L ≧ 0} and The set maximum speed generating circuit 166 of 1 is selected.
At that time, in the circuit 166, as shown _{in FIG} .
₁₁ , the pump control circuit 164 is connected to the swash plate 8.
A signal Z is outputted to the drive device 10 to move the motor to the position corresponding to X _L1 at a slow speed of α ₁₁ as shown from t ₆ to t ₈ in FIG. Therefore, even if the operating lever is operated suddenly and inadvertently during fine operations with a small amount of operation, no shock occurs, making it easier to perform detailed operations.

Next, the case where the operating lever is suddenly operated from X _Lnax to -X _Lnax as shown from t ₉ to t ₁₂ in FIG. 6 will be explained. First, from t ₉ to t ₁₀ and from t ₁₀ to t ₁₁ , Y _L ≧
Since 0,X _L < Y _L , comparator 1 in Figure 1
72 outputs "1", comparator 174 outputs " ₀ ", and the third setting maximum speed generating circuit 17 of the contents of _FIG .
0 is selected. Therefore, from t ₉ to t ₁₀ , α ₃₁ to α ₃₃ are output, and from t ₁₀ to t ₁₁ , α ₃₃ is output to the pump control circuit 164 as the set maximum speed, and the slope is outputted as the maximum speed from t ₃ to t ₅ . The board is controlled. At the moment when Y _L <0 after ₁₁ o'clock t, the output of the comparator 172 becomes "0". Since the output of the comparator 174 remains "0", the output of the EXOR circuit 176 becomes "0" and the switch 178 is switched to the a terminal side. Therefore, the first set maximum speed generation circuit 166 shown in FIG. 2 is selected. Therefore, from the operation signal X _L2 at time t ₁₁ to -X _Lnax at time t ₁₂ , the set maximum speed changes from α ₁₃ to α ₁₄ in FIG. 2, and thereafter becomes α ₁₄ . Therefore, the swash plate is shown in Figure 6.
It is controlled at a fast speed as shown from t ₁₁ to t ₁₃ . As a result, it is possible to obtain a quick operation without causing a shock when the actuator is reversely operated.

Next, when the operating lever is operated from -X _Lnax to the neutral position from t ₁₄ to t ₁₅ in FIG. 6, Y _L <0, and since the speed of the swash plate is controlled by the pump control circuit 164, X _L ≧ _YL . Therefore, the output of the comparator 172 is "0", the output of the comparator 174 is "1", and the output of the EXOR circuit 176 is "1". Therefore, the switch 180 is set to the a terminal side, the switch 178 is set to the b terminal side, and the second set maximum speed generating circuit 168 shown in FIG. 3 is selected. Therefore, between _t14 and _t15 , _α21 to _α23 in FIG. 3 are outputted to the pump control circuit 164, and after _t15 , _α23 is outputted to the pump control circuit 164 as the set maximum speed. Therefore, as shown from t ₁₄ to t ₁₆ in Figure 6, the swash plate moves at first at a slow speed of α ₂₃ or less, then at a fast speed of α ₂₃ ,
Similar benefits can be obtained from t ₃ to t ₅ .

Note that in the embodiment shown in FIG.
8 and the circuit 170 can use functions having an inverse relationship with each other, for example, the circuit 16
Similar functionality can be obtained with two circuits, 6 and 170. FIG. 7 shows such a modification of the swash plate maximum speed setting circuit 200, in which the same members as those in FIG. 1 are given the same reference numerals. Further, the circuit 170 is referred to as a second set maximum speed generation circuit.

Reference numerals 202 and 204 are switches, and when the output of the comparator 172 is "0", the terminal a is turned on.
When it is “1”, it switches to the b terminal side. Further, 206 and 208 are inverting amplifiers, which invert the sign of the input signal and output it.

In this circuit 200, Y _L ≧0, X _L ≧Y _L
and when X _L <0, Y _L <X _L, circuit 1 in Figure 11
62, the first set maximum speed generation circuit 16
Select 6. When Y _L ≧0 and X _L <Y _L , the switches 202 and 204 are set to the b terminal side, and the second set maximum speed generating circuit 1 is activated, similar to the circuit 162 in FIG.
Select 70 as is. When Y _L <0 and X _L ≧Y _L , the switches 202 and 204 are switched to the a terminal side. Then, the operation signal X _L input to the second set maximum speed generation circuit 170 is reversed in polarity by the inverting amplifier 206 . For example, if X _L =X _Lnax , circuit 1
The input to 70 is -X _Lnax , and α ₃₃ in FIG. 4 is read out. And its α ₃₃ is an inverting amplifier 208
The sign is reversed, and the value has the same meaning as α ₃₃ in Fig. 3. In the circuit 162 of FIG. 1, if the absolute values of α ₂ and α ₃ for X _L , which is the reversed sign of the second and third set maximum speed generating circuits 168 and 170, are equal, then the circuit 200 of FIG. but,
The same effect as the embodiment shown in FIG. 1 can be obtained.

The embodiment shown in FIG. 1 is an example in which both circuits 162 and 164 are composed of electronic circuits.
It can also be configured with one microcomputer. FIG. 8 shows an example of this, with circuits 162, 164
An arithmetic unit corresponding to is indicated generally by the reference numeral 210.

The calculation device 210 includes a multiplexer 2 that switches between a swash plate position command signal, that is, an operation signal X _L from the operating lever 14 and a swash plate position signal Y _L from the displacement meter 16.
12, and an A/D that converts the analog operation signal X _L and swash plate position signal Y _L into digital signals.
The converter 214, the ROM memory 216 that stores the operating procedure of the arithmetic unit 210, and the
_{Three tables ( i} ), (ii) and
(iii), the RAM memory 220 that temporarily stores X _L , Y _L taken in from the A/D converter, numerical values in the middle of calculation, etc., and the ROM memory 216 according to the operating procedure. A CPU 222 that calculates a swash plate drive signal, and a D/A converter 22 that converts the signal from the CPU 222 from a digital signal to an analog signal and outputs a control signal Z to the drive device 10.
4.

FIG. 9 shows a flowchart of the operating procedure of the arithmetic unit 210 stored in the ROM memory 216.
Hereinafter, according to this flowchart, the calculation device 210
Explain the operation.

The arithmetic device 210 first performs steps a-1 and a-2.
In FIG. 8, multiplexer 212, A/
The operation signal X _L and the swash plate position signal Y _L are read through the D converter 214 and temporarily stored in the RAM memory 220.
Remember. In step a-3, it is determined whether Y _L ≧0. At this time, if Y _L ≧0, step a-
If Y _L <0, go to step a-5. In step a-4, it is determined whether X _L ≧Y _L , and X _L ≧Y _L
If , go to step a-7; if X _L < Y _L , go to step a-6
go to On the other hand, in step a-5, it is determined whether X _L < Y _L , and if X _L < Y _L , the process goes to step a-7, and if X _L ≧
If Y _L , go to step a-8. Step a-6 is ROM
The set maximum speed α ₃ corresponding to X _L is read out from the ROM table (iii) with the same contents as in FIG. 4 stored in 218 and is set as α. Similarly, in step a-7, α ₁ is obtained from the ROM table (i) with the same contents as in Figure 2, and in step a-8, the ROM table (ii) with the same contents as in Figure 3 is obtained.
Read α ₂ from , and set each as α. In other words, in the operation from t ₀ to t ₂ in Figure 6, steps a-3 and a-4
and a-7 were conducted, and the same content as in Figure 2 was carried out.
ROM table (i) is selected, steps a-3, a-4 and a-6 are performed in the operation from t ₃ to t ₅ , and the fourth
ROM table (iii) with the same contents as in the figure is selected, and t ₁₄
In the operation from _t16 , a-3, a-5 and a-8 are performed, and the ROM table (ii) having the same contents as in FIG. 3 is selected. That is, the procedure up to this point executes the function of the swash plate maximum speed setting circuit 162 shown in FIG.

Next, in step a-9, the value near the zero position of the operation signal _XL is corrected as a command value to the swash plate 8 so that it becomes the zero position, and is set as a new _XL . X _L in step a-10
=Y _L are compared. If X _L = Y _L , step a-
15, and a signal Z for stopping the swash plate 8 is output from the D/A converter 224 to the drive device 10. Then, go to step a-16 and return to the beginning. If it is determined in step a-10 that X _L ≠Y _L , the process goes to step a-11. Therefore, X _L and Y _L , and this program (operating procedure)
The time required from the “beginning” to step a-16 t _c
From this, find _X〓L using the formula: _X〓L = (X _L - _YL )/ _tc . This X〓 _L is the swash plate speed when the swash plate is moved by a command that is the same as the signal from the operating lever. Step a-
In step 12, |X〓 _L |≦|α| is determined, and |X〓 _L |≦|
When α|, go to step a-14 and use the D/A converter 22
4 outputs a signal Z that moves the swash plate at a speed of _X〓L . Then, return to the beginning in step a-16. On the other hand, if |X〓 _L |>|α| in step a-12, step a-13
, and outputs a signal to move the swash plate 8 at a speed α.

With the above configuration, arithmetic unit 210 can obtain the same effect as circuits 162 and 164 in FIG. 1.

Note that in the set maximum speed generation circuits 166, 168 and 170, the relationship between α ₁ , α ₂ and α ₃ and _XL has the characteristics shown by the solid lines in FIGS. 2 to 4, but α ₁ , α ₂ and α ₃ may be changed in a curved line as shown by a broken line, or may be changed in a stepwise manner.

Further, although the above embodiment is an example in which the control system of the present invention is applied to a closed circuit hydraulic circuit device, it can also be applied to an open circuit hydraulic circuit device as disclosed in Japanese Patent Application No. 55-45386. Applicable.

As is clear from the above, according to the present invention, during normal operations in which the operating amount of the operating lever is large, the operating speed of the variable displacement member of the variable displacement hydraulic pump is limited to below the first set maximum speed. , the acceleration of the actuator can be suppressed to a predetermined value or less, and the actuator can be operated smoothly without shock, and the displacement volume can be varied during emergency stops, positioning of the actuator load, and reverse operation. Since the limit value of the operating speed of the member is set to the second or third set maximum speed which is higher than the first set maximum speed, the actuator can operate quickly.

In addition, since the first set maximum speed is set to a value whose absolute value increases as the absolute value of the operation signal increases, the actuator can operate with almost no shock even when the actuator is started or when it is finely operated. be able to.

Furthermore, the second and third set maximum speeds are set to values whose absolute values increase as the operating signal becomes smaller or larger depending on the direction of change of the operating signal. Even if the control lever is returned slightly when the control lever is at or near the maximum operation amount position, no shock will occur, making it easy to make delicate speed adjustments of the actuator. Also, during reverse operation, quick actuator operation with less shock can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the control device of the present invention. FIGS. 2, 3, and 4 show the operating signal X _L and the maximum set speed α in the first, second, and third set maximum speed generation circuits of the embodiment shown in FIG.
₁ , α ₂ and α ₃ . FIG. 5 is a circuit diagram showing details of the pump control circuit in the embodiment of FIG. 1. FIG. 6 is a timing chart showing changes in the operation signal X _L and the swash plate position signal Y _L when the operation lever is operated in the embodiment shown in FIG. FIG. 7 is a circuit diagram of a swash plate maximum speed setting circuit when the second and third set maximum speed generating circuits are combined into one in the embodiment shown in FIG. FIG. 8 is a block diagram showing an arithmetic unit when the embodiment of FIG. 1 is realized by a microcomputer. FIG. 9 is a flowchart showing the operation procedure of the arithmetic unit shown in FIG. 8. In the figure, symbols 2...Hydraulic circuit, 4...Variable displacement hydraulic pump, 6...Hydraulic actuator, 8...
Displacement variable member (swash plate), 14... operating device (operating lever), 16... detecting device (displacement meter),
160...control device, 162...maximum speed setting circuit, 164...pump control circuit, 166...first
Setting maximum speed generating circuit, 168... Second setting maximum speed generating circuit, 170... Third setting maximum speed generating circuit, α ₁ ... First setting maximum speed, α ₂
...Second maximum speed setting, α ₃ ...Second maximum speed setting (third maximum speed setting), 172,174
... Comparator, 176 ... EXOR circuit, 17
8,180...Switch.

Claims (1)

[Scope of Claims] 1. A variable displacement hydraulic pump and an actuator means driven by the pump are connected, and the operating speed of the actuator means is controlled by the position of a variable displacement member of the pump. a control device for a hydraulic circuit configured to control a hydraulic circuit, the control device comprising: an operating device for generating an operating signal for commanding the position of the variable displacement member of the pump and thus commanding the operating speed of the actuator means; a detection device that generates a detection signal indicating the position of the pump; and a pump control device that controls the displacement variable member while limiting its operating speed to a set maximum speed or less based on the operation signal and the detection signal. In the circuit control device, a first set maximum speed and a second set maximum speed larger than the first set maximum speed are set in advance for the operation speed of the displacement variable member, and the operating speed is set in advance according to the operation signal. When the commanded operating direction of the actuator means is equal to its actual operating direction, the first set maximum speed is selected, and the displacement variable member is not in the actual neutral position and the operation signal is activated when the displacement variable member is in the actual neutral position. a maximum speed setting device that selects the second set maximum speed when indicating a neutral position of the member or when the operating direction of the actuator commanded by the operation signal is opposite to its actual operating direction; The pump control device is configured to control the speed of the variable displacement member based on a first or second set maximum speed selected by the maximum speed setting device, and the maximum speed The setting device includes a first means for generating the first set maximum speed, and a second means for generating the second set maximum speed,
The set maximum speed is in a functional relationship with the operation signal such that its absolute value increases as the operation signal changes to move the displacement variable member away from its neutral position, and the second setting The absolute value of the maximum speed increases as the operation signal changes the displacement variable member from one of its normal and reverse maximum positions to the neutral position, and the operation signal increases the displacement variable member. A control device having a functional relationship with the operation signal such that when the variable member is moved from near the neutral position to the other maximum position, the absolute value becomes larger. 2. The control device according to claim 1, wherein the maximum speed setting device includes second and third means for generating the second maximum speed setting,
In the second means, the second set maximum speed is a positive value and increases as the operation signal changes so as to move the displacement variable member from the opposite maximum position to the neutral position. is in a functional relationship with the operation signal such that when the operation signal changes to move the displacement variable member from near the neutral position to the normal maximum position, the third In the means, the second set maximum speed is a negative value, and as the operation signal changes to cause the displacement variable member to move from its normal maximum position to a neutral position, its absolute value increases. is in a functional relationship with the operation signal such that when the operation signal changes to cause the displacement variable member to move from near the neutral position to the opposite maximum position, its absolute value becomes larger. Control device. 3. In the control device according to claim 1 or 2, the first set maximum speed is such that the operation signal causes the displacement variable member to move from its neutral position to its normal maximum position. and a negative value that increases in absolute value as the operation signal changes to move the variable displacement member from its neutral position to the opposite maximum position. A control device that is in a functional relationship with the operating signal so as to take a value. 4. In the control device according to claim 2, the maximum speed setting device has a first position where the second maximum speed setting is output and a second position where the third maximum speed setting is output. a first position for outputting the first set maximum speed to the pump control device; and a second position for outputting the output of the first switch means to the pump control device; and a first switch operation means for switching the first switch means to the first position when the detection signal is negative and to the second position when the detection signal is positive; When the operation signal is larger than the detection signal and the detection signal is positive, or when the operation signal is smaller than the detection signal and the detection signal is negative, the second switch means is moved to the first position. When the operation signal is smaller than the detection signal and the detection signal is positive, or when the operation signal is larger than the detection signal and the detection signal is negative, the second switch means is switched to the second switch. and a second switch operating means for switching to two positions.