JPS58165585A - Controller for hydraulic circuit - Google Patents

Abstract

PURPOSE:To suppress the shock when an actuator is started or minutely operated, by controlling the pushing-away capacity varying member of a hydraulic pump, at the max, set speed which increases as the absolute value of the operation signal increases. CONSTITUTION:When an operating lever 14 is sharply operated to the full positive side, the operation signal XL sharply increases up to the signal XLmax. The max. speed signal alphalmin is output with in the range in which the operation signal XL is small, and as the operation signal XL increases, the speed signal alphal which increases in proportion to the increased operation sigal XL is output, and when the operation signal XL veaches the its max. Level, the max alphalmax is output. Therefore, the inclination speed of a swash plate 8 reduces and the acceleration speed of an actuator 6 is kept small, when the operation is started, so the shock in case when the actuator 6 is started is small.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a variable displacement hydraulic pump connected to actuator means driven by the pump, the speed of said actuator means being controlled by the position of a variable displacement member of the pump, in particular The present invention relates to a control device for a hydraulic circuit that controls the acceleration of an actuator means by limiting the operation speed of the displacement member iiJ of the pump to a predetermined maximum speed or less.

A hydraulic circuit that consists of a variable displacement hydraulic pump and an actuator driven by the pump is connected, and the speed of the actuator is controlled by the position of the variable displacement member of the pump. It has been proposed for use in machinery and hydraulic excavators for coal mining, etc. In this case, for example, in a hydraulic excavator, the boom, arm, bucket,
Working members such as a traveling body and a revolving body are driven by a hydraulic cylinder, a hydraulic motor, etc. that constitute an 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 displacement variable member or swash plate of the pump connected to the boom cylinder is rapidly operated. If the displacement is increased rapidly,
The boom cylinder is 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 driving, the driver shakes due to 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 problem, a control method for controlling the displacement variable 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 Publication No. Showa 56-5900
Report 6.3.9 (Proposal, Ot-C, -.1. As mentioned above, in a hydraulic circuit device, the operating speed of the actuator is determined by the displacement of the variable displacement hydraulic pump. is determined by the position of the variable displacement member.The variable displacement member is the 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. Actuator acceleration is controlled by varying the speed of movement of the swashplate.

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 greater than the set maximum speed, the set maximum speed is applied, and if it is smaller, the change rate of the position command value remains unchanged, and the position command value is increased or decreased, and the swash plate position is While comparing the output of the displacement meter for detection, the output is sent to the swash plate drive ``vM:''.Thus, the variable displacement hydraulic pump plate sets the operating speed and determines its position from the maximum speed device. It is controlled to move to the position commanded by the operating lever. With this configuration, smooth operation without shock can be achieved by setting the maximum speed to a value suitable for the work member driven by each actuator. C. This is called actuator acceleration control or swash plate speed control.

By the way, the maximum speed setting is such that when the control lever is suddenly operated from neutral to full, the actuator does not move slowly; It is set to an appropriate constant value that causes little damage. 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 low and delicate operations are desired where even the slightest shock can be a problem. For example, when you want to position the front end of a hydraulic excavator (bucket), even if the set maximum speed is a value that does not normally cause problems in response to minute movements of the boom lever, the excavator body may move slightly. It shakes and makes positioning difficult. Therefore, even during such fine operation, if the operating lever is suddenly moved, the actuator moves at the set maximum speed, causing a jam. Furthermore, even during normal operation, the pressure at the start of actuator movement is affected by the swash plate speed, so in conventional control methods, a peak pressure occurs at the start of actuator movement, causing a shock.

An object of the present invention is to enable the actuator to perform smooth, not sluggish operation during normal operations in which the amount of operation of the control lever is large, and also to allow the actuator to operate with almost no shock when the actuator is started or when the actuator is slightly operated. It is an object of the present invention to provide a control device for a hydraulic circuit that can perform the following steps.

In order to achieve this object, in the present invention, the displacement variable member of the hydraulic pump is controlled at a set maximum speed that is in a functional relationship with the operation signal such that it increases as the absolute value of the operation signal increases. It is.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5b.

In FIG. 1, a hydraulic circuit is generally indicated by the reference numeral 2, and the hydraulic circuit arrangement 2 includes a variable displacement hydraulic pump 4 and a hydraulic motor or actuator 6 driven by the pump 4 in a closed circuit. Consist of connected. 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 changed 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 is increased or decreased by changing the position of the swash plate 8. Further, 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 can be any servo valve mechanism capable of driving the swash plate 8 to a position according to a human power signal, and may have the structure shown in FIG. 3 of International Publication No. WO81101031. ′ can be □＼. ,,.

Note that in order to simplify the structure of the hydraulic circuit apparatus in FIG. 1, accessory members such as a flushing valve are omitted.

The hydraulic circuit 2 (controlled by a control device 12 which is an embodiment of the present invention) is an operating device that instructs the position of the swash plate 8 and instructs the operating direction and operating speed of the actuator 6. By inputting the operation lever 14, the displacement meter 16 that detects the position of the swash plate 8, the output signal of the operation lever 14, that is, the operation signal X■, and the output signal of the displacement detector 16, that is, the swash plate position signal YI, A maximum speed setting circuit 20 that indicates the maximum value of the operating speed of the plate 8, an operation signal XI, a swash plate position signal Y1., and an output signal of the circuit 20, that is, a maximum speed signal α.
and an output signal Z for driving the drive device 10.
and a pump control circuit 22 that generates.

In the set maximum speed generating circuit 20, a maximum speed αl for the operating speed of the swash plate 8 is preset as a function of the operation signal xI, as shown in FIG. 2, for example. That is, the circuit 20 receives the operation signal X1. For example, if the absolute value of
When the speed is less than or equal to XLI, which is indicated by =1x, the maximum speed is αI min"1., and when the absolute value of the operation signal x1 exceeds XLI, the operation signal X1 is output to αlm1n.
It outputs α1, which is a value that increases in proportion to the absolute value of °, and when the absolute value of the operation signal XL becomes equal to or larger than a predetermined value close to XL, nax, it outputs αIn+ax.

The pump control circuit 22 has the configuration shown in FIG.

That is, the circuit 22 converts the operation signal X, , to the swash plate position signal Y,
, and a differentiator 42 that differentiates the deviation signal ΔX that is the output of the adder 40 and converts it into a large change amount Δ with respect to time, and ΔX is input to the a terminal of the switch 44. Ru. The circuit 22 also has a comparator 46, which determines whether the operation signal xl is positive or negative, and when xl is ≧0, outputs a signal "1" with a level of NO1 and switches the switch 48 to the b terminal side. The set maximum speed signal α input to the b terminal is directly input to switch b of the switch 44.
When X <, O, low level signal 1 is sent to the terminal.
Output 101+ and switch switch 48 to the a terminal side,
The set maximum speed signal α1 inputted to the a terminal and inverted to a negative value by the inverting circuit is sent to the b terminal of the switch 44. The circuit 22 also includes an absolute value circuit 52 which takes the absolute value 1Δ statement 1 of the output 2 sentences of the differentiator 42, and determines the magnitude of 1Δ Then switch 44 to the b terminal side, send α or - to the amplifier 56, and output 1Δ
It has a comparator 54 which switches to the terminal side and sends the two sentences to the amplifier 56. The signal Z amplified by the amplifier 56 is sent to the swash plate drive device 10.

Therefore, the pump control circuit 22 receives the operation signal x1. and the swash plate position signal YI, and also compare the absolute value of the rate of change of the operation signal xI7 1Δ large 1 with the set maximum speed α1, 1Δ
When the intersection I<α1, the signal Z that drives the swash plate 8 to the position according to the operation signal Xl is output at a speed of 2 seconds, and 1Δ intersection 1≧0.
1, the operation signal X1. A signal Z is output to drive the swash plate 8 to a position corresponding to the position. Therefore, the swash plate 8 receives the operation signal xL while being limited to a speed below the set maximum speed αl.
You can move to the position indicated by.

The operation of the control device 12 will be explained. When the operating lever 14 is suddenly operated fully from the neutral position to the positive side, the operating signal KARI becomes X!, as shown in FIG. 4a. , max
It increases rapidly until. In addition, in a range where the operation signal xl is small, a small maximum speed signal αI+nin is output,
When the operation signal XL becomes thicker (when the operation signal XL becomes thicker, it outputs α1 which becomes larger in proportion to it, and when the operation signal XI□ reaches the maximum or its vicinity, it outputs the maximum '1m:+x.
As shown in FIG. b, the tilting speed of the swash plate 8 at the start of operation is small, and the acceleration of the actuator 6 at the start of the operation is also small, so there is little shock when the actuator 6 is started. Furthermore, since the subsequent tilting speed of the swash plate 8 gradually increases, the movement of the actuator 6 does not become slow.

In addition, when the operating lever 14 is suddenly operated from the neutral position to the positive side, for example, within the range of 1/4 of the maximum operating range, lTl; Signal X1. increases rapidly to X 1.1, but αI+nin is output as the maximum speed signal α1. Therefore, as shown in FIG. 8b, since the tilting speed of the swash plate 8 is small, the acceleration of the actuator 6 is small, and no shock that would affect fine operation occurs.・:1. .

,,,,,・4・,, Margin below Another embodiment of the invention will be described with reference to FIG.

In FIG. 6, the same members as in FIG. 1 are given the same reference numerals. In the embodiment of FIG. 6, the control device is generally designated by the reference numeral 121, and the set maximum speed generating circuit 21 includes a first set maximum speed generating circuit 24 in which a first set maximum speed α1 is preset, and a first set maximum speed generating circuit 24, in which a first set maximum speed α1 is preset. The second larger than the set maximum speed α1
A second set maximum speed generation circuit 26 is provided in which the set maximum speed α2 of is set in advance. The first maximum setting speed generating circuit 26 is completely similar to the maximum setting speed generating circuit 20 shown in FIG. The maximum speed α1 having a functional relationship with the signal is output. The second set maximum speed α2 is at the time of emergency stop, a., and when positioning the load of the cutter.

The operating speed of the swash plate 8 is such that the actuator can quickly operate when the direction of operation of the actuator is suddenly reversed.

One of the two set maximum speed generating circuits 24 and 26 is selected by a changeover switch 28.

Comparators 30 and 32 are operated by ζ-14 respectively.
The operating signal XL from the displacement side 16 and the detection signal Y from the displacement side 16 are determined to be negative if IF is negative, and the positive value is the level signal ゛'
1", and when negative, outputs a low level signal "0". Positive of the operation signal XL and detection signal YL means one direction of excitation of the actuator 6, and negative means operation of the other direction. When the input is zero, the controller 60.32 may output either °' 1 "-1 or "0. −
- If they match, it outputs "°0", and if they do not match, it outputs "1"'.The window controller 36 outputs "1" when the human power is zero or near zero, and outputs "o" for other human power values. Output. The logical sum (OR) 38 is connected to its output "0"" and switches the selector switch 28 to the a side, and the output "
1" to switch the selector switch 28 to the 1) side. The range near the input zero where the output of the window controller 36 becomes '1" is matched with the dead zone of the pump control circuit 22. This dead zone is caused by unnecessary displacement of the hydraulic pump 4 due to slight movement of the operating lever 14 in the neutral position.
It is meant to prevent the movement of the Pump control circuit 2
The configuration of 2 is similar to that shown in FIG. 6 above.

Next, the operation of the control device 121 will be explained.

When actuator O is stopped and the operating lever 14 is tilted to the positive side, the pump control circuit 22 sends a signal to the drive device 10 to move the position of the swash plate 8 from the neutral position to one side. At this time, the operation signal XL from the operation lever 14 and the displacement meter 1
6 detection signals Y1, are both positive, and as a result, the output of the comparators 30 and 32 becomes °'1'', and Ex
The output of the OR circuit 64 becomes °°0''. Also, since the operation signal XL is no longer near zero, the output of the regulator 3B at the wind controller becomes °0''. Therefore, OR circuit 6
8 becomes 0, the changeover switch 28 is switched to the a side, and the first set maximum speed α1 is selected and input to the pump control circuit. Therefore, operation renoku-14
If the increasing speed of the position command value of the operation signal XL exceeds the first set maximum speed α1 due to a sudden operation, the pump control circuit 22 adjusts the operating speed of the swash plate 8 to match the first set maximum speed α1. control so that Thus, the acceleration of the actuator 6 is limited to a value equal to or less than the first set maximum speed α1, and the same control as in the embodiment shown in FIG. 1 is performed.

Even when the operation signal XL of the operation lever 14 and the detection signal of the displacement meter 16 are both negative, OI (the output of the circuit 38 is "'0"
'', and the first set maximum speed α1 is selected, so the pump control circuit 22 performs control while limiting the operating speed of the swash plate 8 to 1 less than the first set maximum speed α1.

When the operating lever 14 is returned to the neutral position in order to suddenly stop the actuator 6, the output of the window comparator 3 becomes "'1" and O)? The output of the circuit 38 becomes ゛1'', the selector switch 28 is switched to the 1) side, and the second set maximum speed α2 is selected.As a result, the operating speed of the swash plate 8'1 becomes the second set maximum speed α2. Maximum speed set in 2 is limited to α2 or less.
,1j□,,,,11・tii,,D g Ji *
□It will be larger than when using α1. Therefore, the actuator 6 can be greatly decelerated and stopped quickly.

When reversing the operating direction of the actuator O from one side to the other, for example, when the operating lever 14 is instantaneously switched from the +F side to the negative side, the position of the swash plate 8 is determined by the lever whose operating speed is limited by the pump control circuit 22. Therefore, the position command value changes later than the position command value from the operating lever 14, and the detection signal YL of the displacement meter 16 remains positive, while the operating signal X1 of the operating lever 14 becomes negative. As a result, the conopalator 30
The output of comparator 32 is ``1'', and the output of comparator 32 is ``0''.
, and the output of the EXOR circuit 64 is "1".
becomes.

Therefore, the changeover switch 38 is switched to the l) side and the second
The set maximum speed α2 is selected, and the limit value of the operating speed of the swash plate 8 is greatly increased, causing the actuator 6 to be greatly decelerated. Then, when the actual position of the swash plate 8 becomes negative, the output of the '7 comparator 30 becomes "o", and EXql'
When the output of the circuit 64 becomes "o", the set maximum speed α1 of the first i is selected.

When positioning the load on the actuator B, by rapidly returning the operating lever 14 to the neutral position, the second set maximum speed α2 is selected as in the emergency stop W, so the actuator 6 is greatly decelerated and stopped quickly. I can do it.

Therefore, according to the embodiment of FIG. 6, in addition to the effects of the embodiment of FIG. 1, the limit value of the operating speed of the displacement material member is set to Since the second set maximum speed is set higher than the set maximum speed, the actuator can operate quickly.3 The embodiment shown in FIG. In this example, both of them are constructed from electric f circuits, but they can also be constructed from one microconbeater. FIG. 8 shows an example of this, and the arithmetic units corresponding to the set maximum speed generation circuit 22 and the pump control circuit 22 are not shown as a whole with the reference numeral 140. Arithmetic device 140
are a multiplexer 142 that switches and outputs the operation signal XL and the swash plate position signal)'□, an A/D converter 144 that converts the operation signal X14 and the swash plate position signal YL, which are analog signals, into digital signals, and an operation procedure. ROM memory 146 storing XL and α1 tables corresponding to the functions shown in FIG. 6, and α2 corresponding to the setting values of the circuit 26 in FIG.
ROM memory 148 and A/D converter 144 that store
R, AM memory 150, R, which temporarily stores the operation signal XL and the swash plate position signal Y taken in from the operation signal Y.
Calculate according to the operating procedure of the OM memory 146 ・CP
U 152, converts the digital signal from the CPU 152 into an analog signal and outputs it to the swash plate drive device 10 1)/A
It has a converter 154.

FIG. 8 is a flowchart of the operating procedure of the arithmetic unit 140 stored in the l'tOM memory 146.

Hereinafter, the operation of the arithmetic device 140 will be explained according to this flowchart.

First, when the operation lever 14 is operated to the positive side from the stopped state, the operation signal XL and the swash plate position signal Y□ are positive, and since the operation signal XL is thicker than the swash plate position signal Y1, step a - Do steps 1, 2, 6, 4, 5, 8, 9, 10, 11 and 14. That is, in step a-5, +? , the operation signal XL as the set maximum speed signal α from the 0M memory 148
, and controls the swash plate drive device 1o so that the swash plate 8 tilts at a speed lower than the speed corresponding to the set maximum speed signal α1. At this time, α1 can take a value from α1m1n to α1□11i1X according to the increase in XL, so even if the operating lever 14 is suddenly operated from the neutral position to the full position, the shock to the starting crystal of actuator B is small, and The movement of the actuator 6 does not become slow.

Further, the operation lever 14 may be moved to the operating amount XL from the neutral position, for example.
When a fine operation is performed by rapidly operating ('V) by 1/4 of max, α1 read in step 2I-5 is αHn
Since it indicates in, the acceleration of the actuator 6 is small,
There is no possibility of any nuisance.

When the position of the swash plate 8 becomes a value corresponding to the amount of operation of the operation lever 14, when the operation number XL and the swash plate position signal YL become equal, the procedure is 1-1. .2.6
．． 4.5.8.16 and 14 are performed, and the swash plate drive device 10 is controlled so that the swash plate 8 stops at that position. From this state, when the operating lever 14 is returned to the neutral position, but not yet to the negative side, the operating signal XL becomes zero or less than zero, and the operating signal XL becomes smaller than the swash plate position signal YL, so step a -1, 2, 6, 4, 7, 8, 9, 1
Do steps 0, 11 and 14. That is, in step a-7, α2 is read from the ROM memory 148 as the set maximum speed signal α,
The swash plate drive device 10 is controlled so that the swash plate 8 is tilted at a speed lower than the speed corresponding to the set maximum speed signal α2. Therefore, the actuator 6 can be greatly decelerated. In addition, in the embodiment shown in FIG. 6, a second set maximum speed generation circuit 26 is provided which generates the second set maximum speed α2 at the time of emergency stop, positioning of the actuator load, and reverse operation. , an arithmetic circuit for calculating the differential value of the operating signal XL of the operating lever may be provided, and the arithmetic circuit ρ output section may be connected to the b-side terminal of the brown kidney inochi 28.

In this way, when performing the above operation, it is possible to make the operation of the actuator faster than or equal to the speed corresponding to the second set maximum speed α2.

In the above embodiment, the relationship between the operation signal XL and the set maximum speed signal α1 is determined as shown in FIG.
1 may be increased, or the set maximum speed signal α1 may be increased in proportion to the square of the operating signal XL, and the set maximum speed signal α1 may be increased by the operating signal X1. It may be increased stepwise as the absolute value of . That is, the set maximum speed signal α1 may be determined to increase as the absolute value of the operation signal XL becomes sharper.

As explained above, according to the present invention, the maximum speed of the variable displacement displacement part of the hydraulic pump for machihenta is set to a value that increases as the absolute value of the operation signal increases, so that the operation of the actuator becomes slow during normal operation. It is possible to operate the actuator without causing any shock, and with almost no shock occurring even when the actuator is started or when the actuator is finely operated.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a preferred embodiment of the hydraulic circuit control device of the present invention, and FIG. 2 is a set maximum speed α1 set in the set maximum speed generation circuit of FIG. 1 and an operation signal XL.
FIG. 6 is a circuit diagram showing details of the pump control circuit of the control device shown in FIG. 1, and FIG.
Figures 41 and 41) are timing charts showing changes in the operation signal XL and the swash plate position signal YL when the operating lever in Figure 1 is operated to the maximum, Figures 5d and 5
Fig. b shows a timing chart similar to Figs. 4a and 4b when the operating lever of Fig. 1 is insensitively operated, and Fig. 6 shows another preferred implementation of the hydraulic circuit control device of the present invention. FIG. 7 is a block diagram showing an arithmetic device that implements the embodiment of FIG. 6 using a microcombinator, and FIG. 8 is a flowchart showing the operating procedure of the arithmetic device of FIG. 7. - FIG. 2...Hydraulic circuit 4...Variable displacement hydraulic pump 6...Hydraulic actuator 8...Displacement volume U-shaped member (swash plate) 12...Control devices 1 to 4...Operation device (operation lever) 16...Detection device (displacement meter) 20.21...Maximum set speed generation circuit 22...Pump control circuit 121...Control device *1 Figure, t2 Figure ~. O゛5□M

Claims (1)

[Claims] A control device for a hydraulic circuit comprising a variable displacement hydraulic pump and actuator means driven by the pump, the control device commanding the position of a variable displacement member of the pump and thus commanding the operating speed of the actuator. an operating device that generates an operation signal; a detection device that generates a detection signal indicating the actual position of the variable displacement member; and a control device that controls the position of the variable displacement member based on the operation signal and the detection signal. In a hydraulic circuit control device having a pump control device that controls the operating speed while limiting it to a set maximum speed, the set maximum speed is in a functional relationship with the operating signal such that it increases as the absolute value of the operating signal increases. A hydraulic circuit control device characterized by: