JPS6175135A - Control device for working machine - Google Patents

Abstract

PURPOSE:To prevent lowering of the pressure of a control circuit and to smooth operation of an arm cylinder, by providing a control computing means which gradually changes in the vicinity of a switching pressure a switching valve being switched by means of a pilot pressure for the direction switching valve of a bucket cylinder. CONSTITUTION:A first actuator 6 is connected to hydraulic pumps 8 and 9 through pilot control type direction switching valves 10 and 11, m respectively, and a second actuator 7 is connected to a hydraulic pump 9 through a pilot type direction switching valve 12. A switching valve 19 is situated to one of the pilot control circuits of the first actuator 6, switching thereof is effected by means of pilot pressure oil fed from the pilot control circuit of the second actuator 7, and pressure oil from the hydraulic pumps 8 and 9 are joined or branched. Further, a control computer 20 detects the state of a bucket 4, not shown, and switching of the switching valve 19 is gradually effected by means of an output from an electric hydraulic conversion valve 21.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a control device for working machines such as hydraulic excavators, bulldozers, hydraulic cranes, etc. The present invention relates to a control device for a working machine equipped with a hydraulic circuit operated by a directional control valve.

[Background of the invention]

In conventional working machines such as hydraulic excavators.

In order to operate a plurality of work actuators, pressure oil from a plurality of hydraulic pumps is distributed to each work actuator via each direction switching valve. In order to operate each work actuator efficiently, the pressure oil of each hydraulic pump is combined or divided and supplied to each work actuator.

FIG. 3 shows an operation diagram of packet cutting edge linear excavation control of a roading excavator as disclosed in Japanese Patent Application Laid-open No. 59-48532 and Japanese Patent Laid-Open No. 59-48533. 1 is the excavator body, 1a is its crawler track, 2 is the boom, 3 is the arm, and 4 is the packet.

5 is a boom cylinder for raising and raising the boom; 6 is an arm cylinder for swinging the arm; and 7 is a packet cylinder for rotating the packet. In addition, Pa is the excavator body 1 and boom 2.
The pivot point between boom 2 and arm 3, P+ is the pivot point between boom 2 and arm 3, P
P3 is the pivot point between the arm 3 and the packet 4 (hereinafter referred to as the arm tip point), and P3 is the cutting edge point of the packet 4.

Packet edge straight drilling is performed as follows.

First, the blade of packet 4 is held almost vertically when approaching R band 11! Then, while rotating the packet 4 and lowering the boom 2, the arm 3 is pushed out to perform control so that the locus of movement of the packet cutting edge P3 becomes horizontal. When the packet 4 assumes the position shown in ■, stop rotating the bucket 1-4, and then lower the boom 2 while pushing out the arm. The arm tip point P: always moves parallel to G and L, and the packet The attitude of the packet 4 reaches the state (2) while the angles formed by the packet 4 with the G and L directions are kept almost constant by the old parallel link mechanism constituted by the arm 3 and the packet cylinder 7.

FIG. 4 shows the operating hydraulic circuit for the arm cylinder 6 and packet cylinder 7 of the loading excavator, where 8 and 9 are hydraulic pumps, and 10 and II are hydraulic pumps 3 and 9, respectively, which supply hydraulic pressure to the arm cylinder 6. 12 is a pilot operated directional switching valve that supplies and distributes pressure oil from the hydraulic pump 9 to the packet cylinder 7; 13 is an arm operating lever; 14 is a packet operating lever; 15 is an arm A pilot valve 16 generates a pilot pressure according to the amount of operation of the operating lever 13, and 16 is a pilot valve II that generates a pilot pressure depending on the amount of operation of the packet operating lever 14.

18 are the pilot valves 15 to directional control valves 10.
11 is a pilot operation circuit, 19 is a switching valve provided in the middle of the pilot operation circuit 18, and 20 is a control'/iL calculator that controls the packet according to the amount of extrusion of the arm 3 when performing the above-mentioned packet cutting edge linear excavation under automatic control. 4 times OX is calculated and output as an electrical signal, and a signal that senses that the packet 4 has reached the state H in Fig. 3 is inputted to switch the switching valve 19 from the 5th row to the 3rd row in the diagram. Outputs an electrical signal to switch between rows. Reference numeral 21 denotes an electro-hydraulic conversion valve that converts the electrical signal output from the control calculator 20 into pilot pressure. 22 is a shuttle valve that connects the pilot pressure of the pilot valve 16 with the electro-hydraulic conversion valve 2.
1 and select the higher pressure.

23 is a pilot operation circuit connected to the shuttle valve 22, which is branched in the middle, and the first branch circuit 23a is a switching valve.

The two-branch circuit 23b to 19 is connected to the directional control valve 12.

The above packet has a straight edge! When performing A excavation under automatic control, only the arm operation lever 13 is operated, the amount of extrusion of the arm 3 (the rotation angle at the pivot point P1 or the amount of expansion and contraction of the arm cylinder 6) is detected, and the amount of extension and contraction of the arm cylinder 6 is adjusted accordingly. The rotation angle at the pivot point Po of the boom 2 and the rotation angle at the arm tip point P2 of the packet 4, which should make the locus of the packet cutting edge point P3 horizontal, are calculated and output by the control calculator 20, and are outputted through the operation port g4& A pilot-operated directional control valve (not shown) for the boom and a directional control valve 12 for the packet are operated by pilot pressure. In FIG. 4, the boom operation circuit is omitted, and only the nine-packet maintenance circuit includes the electro-hydraulic conversion valve 21, shuttle valve 22. It is illustrated as a pilot operation port 23.

On the other hand, the first option for manual operation is the arm control lever! 3,
The packet operation lever 14 and the boot shown in the figure,
The packet cutting edge straight line excavation will be performed by cutting the l+% cutting levers respectively. In addition, when attempting to pressurize the rotation ribs of packet 4 during automatic excavation, use the packet operation L/
This is done by operating the bar 16.

Now, during straight cutting of the packet cutting edge, a packet rotation signal is output from the control calculator 20 (or the pilot valve 16) from the third @ state ■ to the H state, so the switching valve I9 is switched to the 5th position row, and the pilot operation circuit 18 is cut off by the switching valve 19, so the pilot valve! The pilot pressure from 5 is only sent to the directional control valve lO, and no pilot pressure is applied to the directional control valve 11, so the arm cylinder h is moved only by the pressure oil from the hydraulic pump 8. ! being moved.

When the packet 4 reaches the H state, the control arithmetic unit 20 (valve 16 to the straddle pylon 1) outputs the signal, so
The switching valve 19 switches from the b position to the illustrated a position at It2, and the pilot pressure of the pilot valve 15 changes to the direction switching B, H.
z, the arm cylinder 6 is driven by the combined pressure oil of the hydraulic pump 8.9, and the speed Hl increases sharply, but when the switching valve 19 switches, the arm cylinder 6 is driven by the combined pressure oil of the hydraulic pump 8.9.
Since pressure oil from the pilot valve 15 flows into the conduit 18 between the switching valve 19 and the switching valve 19, the pilot pressure in the pilot operation circuit L7 may temporarily drop for a moment.

This is caused by the fact that the speed of the arm cylinder 6 slows down one step and then suddenly speeds up. This becomes more noticeable as the pipe line between the directional switching valve 11 and the switching valve 19 becomes longer.

Therefore, there is a drawback that the switching operation of the arm 3 is not performed smoothly, causing jerky operation, and also has a negative effect on the accuracy of straight line cutting of the packet cutting edge. Particularly when performing automatic excavation operation, there is a problem that the linearity during excavation is impaired due to the influence of delay in control response.

[Purpose of the invention]

In view of the above-mentioned conventional problems, the present invention drives a plurality of work actuators using pressure oil from a plurality of hydraulic pumps through directional switching valves, and the first seven actuators drive each of the plurality of hydraulic pumps. The second actuator is connected via a pilot-operated directional control valve, and the second actuator is driven by pressure oil from a hydraulic pump via the pilot-operated directional control valve. One of them was equipped with a switching valve, and this switching valve was switched by pilot pressure oil from the pilot operation circuit of the second 7-cut unit, so that the pressure oil from multiple hydraulic pumps could be combined or divided. The purpose of this invention is to prevent a temporary drop in pilot pressure that occurs when the switching valve is switched in a working machine.

[Summary of the invention]

To achieve this object, the present invention provides a pressure that gradually changes the pilot pressure for the directional control valve of the second actuator near the switching pressure of the directional control valve provided in the pilot operation circuit for the directional control valve of the first actuator. A calculation control means is provided to prevent a temporary drop in the pilot operating pressure of the first actuator when switching the switching valve.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The control calculator 20 in FIG. 4 detects that the packet 4 has reached the state shown in FIG. Calculated from each rotation angle) shi,
The output to the electro-hydraulic conversion valve 21 is lowered to A of the 212I. Then, the output is gradually lowered to B, and then suddenly dropped to zero.

In Figure 2, the vertical axis is the output X of the control calculator 20, and the horizontal axis is time °C.
Let the values of the outputs A and B be the values before and after the pilot pressures A' and B= at the switching positions 1ia and b of the switching valve 19 shown in FIG. In this way, the switching valve 1
9 is the position [Since the switching is gradual from a to b, the opening area of the switching valve 19 gradually changes, and the pilot pressure from the pilot valve 15 gradually acts on the pilot part of the pilot operated directional switching valve 11. , the phenomenon that the pilot pressure of the pilot operation circuit 17 drops momentarily does not occur. Therefore, the arm cylinder 6 is connected to the hydraulic pumps 8 and 9.
The above-mentioned switching operation in which the pressurized oils of 2 and 3 are combined to operate is performed smoothly, the arm 3 does not perform jerky movements, and automatic cutting in a straight line at the cutting edge is not adversely affected.

In addition, when manual operation is performed, the control calculator 20 senses that the packet control lever 14 has been returned to neutral, and from that point on, the output from A to B as shown in FIG. 2 is controlled. If it is generated by the computing unit 20, the switching valve 19 can be gradually switched in the same way, and the above-mentioned switching operation of the arm 3 can be performed smoothly.

FIG. 1 is a flowchart showing specific implementation details of the control calculator 20. As shown in FIG.

First, in block 100, it is detected that the packet 4 has reached the state H in FIG. 3 (packet operation is completed), and in block 101, output X=A is output at time t=o. Block 102 outputs the output x=x−kt, and block 1
In step 03, it is determined whether X≦B, and if NO, in block 104, time 1=1+Δt is set, and the process returns to block 102. If it is determined as Yes in block 102, then in block 105 the output X=O and the switching of the switching valve 19 is completed.

According to the above embodiment, the packet cutting edge is straight #! During excavation, it is possible to smoothly switch the merging drive from the hydraulic pump 8 of the arm 3 to the hydraulic pumps 8 and 9 at the end of the packet operation, which adversely affects the straight line excavation control of the packet cutting edge, especially the excavation linearity during automatic excavation. Never.

As described above, in the present invention, the arm cylinder 6 is connected to the hydraulic pump 8.9 via the pilot-operated directional control valve 10.11, and the packet cylinder 7 is connected to the hydraulic pump 9 via the pilot-operated directional control valve 12. The description has been made by taking as an example the case of straight-line excavation of the packet cutting edge in which the packet cutting edge point P3 is moved along a straight line; however, the present invention is not limited to the above embodiment, and the arm cylinder 6 can be connected to two pilot-operated types. are connected to the hydraulic pumps 8 and 9 through directional switching valves, and a swing motor (not shown) for the upper revolving body of the hydraulic excavator is connected to the hydraulic pump 9 via a pilot-operated directional switching valve (not shown). If connected.

Boom cylinder (not shown) instead of arm cylinder 6
is connected to be driven by two hydraulic pumps, and the left and right travel motors of the hydraulic excavator (not shown)
When a hydraulic pump is operated at the same time as another actuator, the pressure oil from one hydraulic pump is diverted to drive the left and right travel motors, etc. In this case, the pressure oil from multiple hydraulic pumps is combined or divided to drive each work actuator. When switching a switching valve provided in another pilot operating circuit by the pressure of one pilot operating circuit of a circuit, it can be widely applied as a means for preventing a pressure drop in the pilot operating circuit at the time of switching.

Furthermore, the effect of the switching valve 19 shown in FIG. 4 is greater as the pilot pressure width A= and B= at the time of switching is larger, so if a valve with a wider pilot pressure width at switching is used, the effect of the present invention will be further enhanced. Becomes good.

〔Effect of the invention〕

According to the present invention described above, the first seven actuators are connected to the plurality of hydraulic pumps via the plurality of pilot-operated directional valves, and the second actuator is connected to the hydraulic pumps via the pilot-operated directional valves. , and at least one of the plurality of directional valve pilot operating circuits of the first actuator includes a switching valve that is switched by pilot pressure of a directional valve layer pilot operating circuit of the second actuator. In the installed working machine, it is possible to prevent a pressure drop in the operation circuit when switching the switching valve, to allow the first seven cutter units to operate smoothly, and to have an adverse effect on the control operation particularly during automatic control. It is possible to prevent giving.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the specific contents of a control device according to an embodiment of the present invention using a professional chart, Fig. 2 is a diagram showing an example of the control function shown in Fig. 1, and Fig. 3 is a diagram showing a packet cutting edge of a loading shovel. Operation diagram of linear excavation control. FIG. 4 is a diagram showing the arm and packet hydraulic circuits of the loading shovel hydraulic circuit. 6...First actuator (arm cylinder) 7...Second actuator (packet cylinder) 8.9...Hydraulic pump, 10.11.1
2...Pilot operated directional valve, 17,1
8.23...Pilot operation circuit, 19...
...Switching valve, 20...Control computing unit. Figure 1 Figure 2 Artwork'I Figure 3 1a p3

Claims (1)

[Claims] A first actuator is connected to a plurality of hydraulic pumps via a plurality of pilot-operated directional valves, a second actuator is connected to a hydraulic pump via a pilot-operated directional valve, and a second actuator is connected to a plurality of hydraulic pumps via a plurality of pilot-operated directional valves; In the working machine, at least one of the plurality of directional valve pilot operating circuits is provided with a switching valve that is switched by the pilot pressure of the directional switching valve pilot operating circuit of the second actuator. A pressure calculation control means is provided for gradually changing the pilot pressure for the directional switching valve of the second actuator in the vicinity of the switching pressure of the switching valve provided in the pilot operating circuit for the directional switching valve of the first actuator. A control device for a working machine.