JPH1121941A - Hydraulic controller for hydraulic backhoe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic controller for a hydraulic backhoe, by which trouble, in which boom lifting operation is delayed to arm drawing and the pawl end of a bucket is bitten to a ground surface at the time of horizontal drawing operation, is prevented and horizontal drawing operation is conducted simply and surely. SOLUTION: The hydraulic controller for the hydraulic backhoe is constituted so that an oil-passage changeover valve 11 is interposed between a return-oil outlet port 10b at the time of the arm drawing operation of a directional changeover valve 10 for an arm and an oil tank 22 and the oil-passage changeover valve 11 is changed over and worked while being interlocked with the arm- drawing changeover operation of the directional changeover valve 10 for the arm. The controller 21 controls the spool movement of the oil-passage changeover valve 11 so that the speed of arm-drawing operation is made later than the time of arm single operation in the simultaneous operation of boom lifting and arm drawing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for a hydraulic shovel, which is suitable for a combined operation of an arm actuator and a boom actuator provided on a front attachment of the hydraulic shovel.

[0002]

2. Description of the Related Art Conventionally, as a configuration of a hydraulic control device in a hydraulic shovel, a hydraulic control device described in Japanese Patent Application Laid-Open No. 7-189285 is known. This hydraulic control device is shown in FIG.
As shown in FIG. 0, flow control valves 52 and 53 for controlling the flow rates of the pressure oil supplied to the arm cylinder 50 and the boom cylinder 51 of the hydraulic shovel, respectively,
2 and 53, each flow control valve 52, 53
Are provided with variable pressure compensating valves 54 and 55 for compensating the differential pressure between before and after.

In FIG. 1, in the so-called horizontal pulling operation in which the boom raising and the arm retraction are simultaneously performed, a load when raising the entire front attachment is added to the boom raising, so that the load pressure P of the boom cylinder 51 is increased.
BU increases. On the other hand, for arm pulling operation, actual excavation is not performed, but only earth and sand is leveled.
The load pressure PA of the arm cylinder 50 is low, and as a result, in the horizontal pulling operation, the load pressure PBU when the boom is raised is increased.
Is the maximum load pressure.

The pump discharge pressure Ps is controlled by a load sensing control unit to be PBU + ΔPLS, and the pump discharge flow rate Q is limited to a flow rate corresponding to the load pressure PBU + ΔPLS by input torque limiting control. Therefore, when the boom raising and the arm lowering are simultaneously performed, the pump discharge flow rate supplied to the arm cylinder 50 and the boom cylinder 51 becomes insufficient, the load sensing differential pressure becomes ΔPLS ′ smaller than the target differential pressure, and The compensation pressure of each of the variable pressure compensation valves 54 and 55 is ΔPLS ′
Is controlled to be equal to

[0005] Then, the pressure oil introduced into the arm cylinder 50 and the boom cylinder 51 is supplied to the flow control valve 5 based on the insufficient load sensing differential pressure ΔPLS '.
Divided and supplied according to the opening area ratio of the 2,53 meter-in variable diaphragms.

[0006]

As described above, in the conventional hydraulic control apparatus, when the discharge flow rate from the hydraulic pump 58 is distributed to the arm flow control valve 52 and the boom flow control valve 53, the divided flow rate is reduced. Although the ratio can be changed, the control of the boom directional control valve is set to a characteristic that takes into account fine operation, so that it can respond to excavation work, load hanging work, etc. There is an inconvenience that it is not suitable for work requiring responsiveness.

When the boom raising operation and the arm pulling operation are simultaneously performed, if the boom raising operation is delayed with respect to the arm pulling operation, a careful operation is required because the toe of the bucket bites into the ground. It was a burden.

The present invention has been made in consideration of the above-mentioned problems in the conventional hydraulic control device. The arm can be operated without a response delay by operating the arm alone. It is an object of the present invention to provide a hydraulic control device for a hydraulic shovel, which eliminates a drawback that a toe of a bucket bites into the ground when operated at the same time, and enables simple and reliable horizontal pulling operation.

[0009]

SUMMARY OF THE INVENTION The present invention provides a hydraulic actuator for an arm and a boom, a directional control valve for an arm and a directional control valve for a boom for controlling the hydraulic actuator for an arm and the hydraulic actuator for a boom. A hydraulic pump for supplying pressure oil to the directional control valve, an operating body for operating the arm and the boom, detecting means for detecting operating states of the operating body for the arm and the boom, and an oil outlet of the directional control valve for the arm An oil passage switching valve that is interposed in an oil passage communicating the port and the oil tank and that switches from an oil passage restricted position to an oil passage open position in conjunction with the arm direction control valve, and an arm and boom operating body. Switching valve control for delaying the switching operation speed of the oil passage switching valve in comparison with a single operation of the arm operating body in accordance with the operation state detected by the detection means in the state of simultaneous operation. Stage and a hydraulic control device for a working machine comprising comprises a.

It is preferable that the oil passage switching valve of the present invention is operated in proportion to the operation amount of the arm operating body. The switching valve control means detects when the arm pulling operation and the boom raising operation are detected simultaneously, When the horizontal pulling operation is detected, it is preferable that the switching operation speed of the oil passage switching valve is made slower than when the arm operating body is operated alone. Also,
When the horizontal pulling operation is performed, it is preferable that the responsiveness of the oil passage switching valve can be changed according to the operation amount of the boom operating body.

The oil passage switching valve according to the present invention can be constituted by a spool valve which switches the oil passage from the shut-off position to the pressure oil introduction portion of the directional control valve for the arm and returns excess oil to the oil tank. And a spool valve that switches the oil passage from a shut-off position to an oil tank communication position, and a passage from a neutral position that sends pressure oil to a pressure oil introduction portion of an arm directional control valve with the passage narrowed. And a spool valve for switching the oil passage from the shut-off position to the oil tank communication position with the throttle portion. Further, in the present invention, it is preferable to reduce the discharge flow rate of the hydraulic pump when the simultaneous operation of the arm and boom operating bodies is detected by the detecting means.

According to the present invention, when the boom operating body and the arm operating body are simultaneously operated on the boom raising side and the arm retracting side, respectively, for example, a pressure sensor connected to a boom remote control valve, and A boom raising signal and an arm retraction signal are output from a pressure sensor connected to the arm remote control valve, and are provided to the switching valve control means.

[0013] The switching valve control means determines that the simultaneous operation is performed by receiving the respective signals, and switches the oil passage in the oil passage switching valve from the restricted position to the open position via, for example, an electromagnetic proportional pressure reducing valve. The switching operation is controlled so as to be delayed as compared to when the arm operating body is operated alone. This causes the spool in the oil passage switching valve to move slowly. That is, in the case of the simultaneous operation, the movement of the spool in the oil passage switching valve is delayed at the time of rising, and as a result, the retraction of the arm is performed slowly. Therefore, the operator can easily and reliably perform the horizontal pulling operation without paying attention to the claw of the bucket digging into the ground.

Further, since the meter-out opening of the spool in the oil passage switching valve is enlarged as the boom raising operation amount of the boom operating body increases, the responsiveness of the oil passage switching valve is reduced by the boom raising operation amount. The bigger you get, the quicker you get.

Furthermore, when the boom raising and the arm retraction are simultaneously operated, the discharge flow rate of the hydraulic pump is also reduced, so that each operation of the boom raising and the arm retraction is performed slowly, and the horizontal pulling operation is performed. It can be performed more reliably.

On the other hand, when the operating body for the arm is operated alone, the switching valve control means switches the oil passage switching valve via the electromagnetic proportional pressure reducing valve without instructing a delay. Can be faster. In addition,
The spool of the oil passage switching valve operates in proportion to the operation amount of the arm operation body.

When the boom raising and the arm retraction are simultaneously operated, the opening amount of the return oil passage at the time of the arm retraction operation from the arm cylinder is controlled by the arm spool of the arm direction switching valve and the spool of the oil path switching valve. Are defined by the sum of the opening amounts of the meterout openings.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the hydraulic control device for a hydraulic shovel according to the present invention will be described below with reference to the drawings.
FIG. 1 is a side view showing an external configuration of the excavator 1 and shows a state where a horizontal pulling operation is being performed. In the figure, 2 is a traveling body of the excavator 1 and 3 is a traveling body 2
The revolving superstructure mounted on the upper part of the revolving superstructure 4 is a work attachment connected to the front part of the revolving superstructure 3, wherein 5 is a boom, 5a is a boom cylinder as a boom hydraulic actuator, 6 is an arm, 6a is an arm cylinder as an arm actuator, 7 is a bucket, and 7a is its bucket cylinder.

FIG. 2 is a circuit diagram showing a first embodiment of the arm cylinder control device as the hydraulic control device. In the figure, reference numeral 10 denotes an arm pilot switching valve as an arm directional control valve for controlling the arm cylinder 6a, 10L and 10R denote left and right pilot ports of the arm pilot switching valve 10, and 10a denotes an arm (not shown). It is a main spool (hereinafter, referred to as an arm spool) of the pilot switching valve 10.

FIG. 3 is a graph showing the relationship between pilot pressure P ₁ and time t. Pilot and pressure P ₁ is at the arm pulling operation (tilting the arm control lever 12a in the direction of arrow B in FIG. 2), a pilot secondary pressure derived from the hydraulic remote control valve 12 for arm.
As shown in FIG.
Arm spool 10a can move following the arm pull-in operation.

Reference numeral 11 denotes an oil passage switching spool valve as an oil passage switching valve, 11R denotes a pilot port of the spool valve 11, and 11a denotes a switching spool (not shown) of the spool valve 11.

Reference numeral 12 denotes an arm hydraulic remote control valve, and reference numeral 12a denotes an operation lever (operating body) of the arm hydraulic remote control valve 12. 13 is a boom hydraulic remote control valve, and 13a is a boom operating lever (operating body) of the boom hydraulic remote control valve 13.
It is.

Reference numeral 14 denotes a variable displacement hydraulic pump for discharging the main pressure oil, 14a a regulator of the hydraulic pump 14,
Reference numeral 15 denotes a pilot pump serving as a pilot hydraulic pressure source;
Is an oil tank, 17 and 18 are electromagnetic proportional pressure reducing valves, respectively.
Reference numerals 9 and 20 denote pressure sensors as detecting means for detecting the operating states of the hydraulic remote control valve 12 for the arm and the hydraulic remote control valve 13 for the boom, and 21 a controller as a switching valve control means. The outlet A of the arm hydraulic remote control valve 12 is connected to the left pilot port 10L of the arm pilot switching valve 10. Next, the configuration of the arm cylinder control device will be described in more detail with reference to FIGS.

In the embodiment of the present invention, the pressure oil distributed from the hydraulic pump 14 is supplied to the arm pilot switching valve 10,
An arm cylinder 6a for driving the arm 6, a boom cylinder 5a for driving the boom 5, and a bucket cylinder 7a for driving the bucket 7 are provided to a boom pilot switching valve (not shown) and a bucket pilot switching valve (not shown).
Are operated.

In the present invention, the operation lever 12a for the arm is moved to the rising side of the boom 5 (hereinafter, the operation of the boom 5 in the direction of the arrow a shown in FIG. 1 is referred to as boom raising). When the arm 6 is simultaneously operated on the retracting side of the arm 6 (hereinafter, the operation of the arm 6 in the direction of the arrow b shown in FIG. 1 is referred to as arm pulling), the oil flows out from the oil outlet of the arm pilot switching valve 10. The configuration is such that the responsiveness of the arm spool can be adjusted so that the oil amount is reduced at least as compared with the case where the arm operation lever 12a is operated alone. That is, when the arm pulling is performed by extending movement of the arm cylinder 6a, the arm spool 10 to be opened for the passage of the return oil to be returned from the rod-side oil chamber 6a ₁ to the oil tank 22
The opening area Ac1 of the oil outlet a is adjusted.

As a configuration for this purpose, in the arm cylinder control device according to the first embodiment, the return oil outlet port 10b for the arm pulling operation of the arm pilot switching valve 10 is set.
Between the oil tank 22 and the pilot switch valve 1 for the arm.
An oil passage switching spool valve 11 that performs a switching operation in conjunction with an arm pulling switching operation of 0 is provided.

In the pressure sensors 20 and 19, the operation lever 13a for the boom is raised (operated in the direction of arrow C shown in FIG. 1), and the operation lever 12a for the arm is pulled (operated in the direction of arrow B). being adapted to be able to output a boom signal S ₂ and the arm signals S ₁ when each are operated simultaneously, these signals are applied to the controller 21. The controller 21 receives the boom signal S ₂ and the arm signal S ₁ , determines that the respective operation levers are simultaneously operated, and sends the pilot to the pilot port 11 R of the oil passage switching spool valve 11 via the electromagnetic proportional pressure reducing valve 17. exerting a pressure P _2.

An oil passage shutoff position (oil passage restriction position) d of the oil passage switching spool valve 11 shuts off return oil flowing out of the return oil outlet port 10b during an arm pulling operation.
The throttle portion 11b and the check valve 11c disposed in the oil passage cutoff position d are connected to the bottom side oil chamber 6 of the arm cylinder 6a.
It is for preventing the cavitation of a _2.

The oil passage return position E is adapted to transfer a part of the return oil flowing out of the return oil outlet port 10b at the time of the arm pulling operation to the pressure oil introduction portion of the hydraulic pump 14 via the throttle portion 11d and the check valve 11c. _They are merged and returned to the bottom side oil chamber 6a2. Excess return oil is
The oil is returned to the oil tank 22 through the throttle 11b.

[0030] In this arrangement, the oil passage switching spool valve 11 switches the switching valve receives the pilot pressure P ₂ from the oil passage blocking position D to the oil passage feedback position ho. Also,
The switching spool 11a of the oil passage switching spool valve 11 is in proportion to the arm pulling operation amount (the amount of tilt operation angle from the neutral position) of the arm operation lever 12a unless an instruction to delay the rising is output from the controller 21. Can move.

As described above, the arm pilot switching valve 10
Why the oil outlet are connected to the oil passage switching valve 11, if the boom raising and arm pulling are operated simultaneously, the amount of opening of the passage of the return oil from the rod side oil chamber 6a ₁ of the arm cylinder 6a ( The opening area is defined as the meter-out opening of the arm spool 10a (the opening area is defined as Ac1) and the meter-out opening of the switching spool 11a (the opening area is defined as Ac2).
To be set as the sum of An example of an equation for calculating the sum Atotal is as follows.

[0032]

(Equation 1)

When the boom raising and arm retraction are simultaneously operated, the meter-out opening of the switching spool 11a is changed according to the boom raising operation amount of the boom operation lever 13a. The response of the switching spool 11a becomes more agile as the value becomes larger. That is, the meter-out opening (opening area Ac2) of the oil passage switching spool 11a is adjusted in the expanding direction. Next, the operation of the arm cylinder control device having the above configuration will be described.

(A) Arm pull-in operation alone When the arm pull-in operation is performed in the arm pull-in operation, the pressure sensor 19 detects the signal S ₁ and the signal S ₁ is output from the controller 21. And a pilot pressure P ₁ derived from the arm hydraulic remote control valve 12 is supplied to the pipelines 23, 2
4 and acts on the pilot port 10R of the arm pilot switching valve 10. At the same time, the controller 21 outputs the signal S ₁ output from the pressure sensor 19.
, The pilot pressure P ₂ is applied to the pilot port 11R of the oil passage switching spool valve 11 via the electromagnetic proportional valve 17. Thus, the arm pilot switching valve 1
0 is switched from the neutral position to the arm pulling position in response to the pilot pressure P ₁ , and in conjunction with the switching operation of the arm pilot switching valve 10, the switching spool valve 11 is moved from the oil passage shutoff position d to the oil passage circulation position. Switch to position E.

At this time, the switching spool 11a of the switching spool valve 11 operates promptly and agilely in proportion to the amount of arm pulling operation of the arm operating lever 12a, so that the highly responsive arm retracting operation can be performed effectively and reliably. It can be carried out. In addition, since the agile rotation operation of the arm 6 is enabled, the soil removal operation or the like by the bucket 7 based on the rotation operation of the arm 6 can be performed without difficulty.

FIG. 4 is a graph showing pilot pressure P ₂ and time t.
It shows the relationship with. The pilot pressure P ₂ is a pilot secondary pressure acting on the switching spool 11a at the time of arm pulling alone operation described above, is derived from the electromagnetic proportional pressure reducing valve 17, acts on the pilot port 11R of switching spool 11a.

(B) Simultaneous operation of raising the boom and retracting the arm When the raising of the boom and the retracting of the arm are simultaneously operated, the simultaneous operation is detected by the respective pressure sensors 20 and 19 and output from the pressure sensors 20 and 19. Signal S ₂
And the signal S ₁ are given to the controller 21.

The controller 21 generates a time delay (described later) on condition that both the signals S ₂ and S ₁ are given, and the switching spool valve 1 via the electromagnetic proportional pressure reducing valve 17.
Control 1 That is, since the switching spool valve 11 operates in conjunction with the arm pilot switching valve 10, the switching spool 11a moves in proportion to the arm pulling operation amount of the arm operating lever 12a. The arm spool 10
The operation of a is the same as that of the arm pull-in operation alone, but the operation of the switching spool 11a is slower than that of the arm pull-in operation alone.

The graph of FIG. 5 shows the relationship between the pilot pressure P ₂ ′ acting on the switching spool 11a and the time t when the boom raising and the arm retraction are simultaneously performed. In the case of a single operation, the robot rises as indicated by a line 110. However, in the case of simultaneous operation, the rising speed changes according to the operation amount of the boom operation lever. Specifically, as the operation amount decreases, the lines 111 to 113 increase. Is set so that the time until the predetermined pressure is reached is lengthened.
In this way, when the boom raising and the arm retraction are simultaneously performed, the responsiveness of the switching spool 11a is adjusted such that the rise is delayed as shown in FIG. Note that the responsiveness can be adjusted for rising, or for both rising and falling.

The graph of FIG.
FIG. 5 shows the relationship between 0a, the meter retract opening (opening area Atotal by the summation formula) by the switching spool 11a, and the time t. A line 114 indicates a change in the meter-out opening area in the case of the arm retraction alone operation, and a line 115 indicates a change in the meter-out opening area in the case of the boom raising and the arm retraction simultaneous operation. As described above, when the boom raising and the arm retraction are simultaneously performed, the arm retraction meter-out opening is narrowed. Therefore, as shown in FIGS. 5 and 6, when the boom raising and the arm retraction are simultaneously operated, the meter-out opening of the switching spool 11a is narrowed, so that a delay occurs at the time of rising of the arm operation, Thereby, the arm retraction operation is performed gently. Therefore,
The operator need not pay attention to the trouble that has occurred during the simultaneous operation, that is, the fact that the claws of the bucket bite into the ground, and can easily and reliably perform the horizontal retraction operation.

The meter-out opening of the switching spool 11a is adjusted according to the boom raising operation amount of the boom operation lever 13a. The response becomes more agile as the boom raising operation amount increases, and the horizontal pulling operation can be performed. It can be done easier and faster.

FIG. 7A is a flowchart for explaining the response of the switching spool 11a to the boom raising, and FIG. 7B is a graph showing the relationship between the switching spool 11a and the boom raising remote control pressure. .

When it is determined that the arm retracting operation is performed (step S1) and then it is determined that the boom raising operation is performed (step S2), it is determined whether the remote control pressure derived from the boom raising remote control valve 13 is 15 kgf / cm ² or more. It is determined whether the response is no (step S3). If no, the value of boom raising remote control pressure / 15 kgf / cm ² is set as the response sensitivity (step S4). If yes, the response sensitivity is set to “1”. That is, as shown in FIG. 7B, if the operation amount of the boom operation lever 13a is large, the response sensitivity is set to "1" to improve the response characteristic, and the boom operation lever 1
If the operation amount of 3a is below the threshold value of 15 kgf / cm ² , the response sensitivity is set according to the boom operation amount. Specifically, when the set response sensitivity is, for example, 0.5, 1 / 0.5 = 2.0, and the controller 21
The pilot pressure P ₂ gives an instruction to be the maximum for the switching spool valve 11 2.0 seconds over. Therefore, assuming that the control cycle of the controller 21 is 20 msec, 2000 msec
/ 20 msec = the pilot pressure P ₂ at 100 times command delay control such that the maximum is performed.

In the present embodiment, when the boom raising and the arm retraction are simultaneously operated and the signals output from the pressure sensors 20 and 19 are input to the controller 21,
When the controller 21 determines that both signals are present, the controller 21 controls the regulator 14 a of the hydraulic pump 14 through the electromagnetic proportional pressure reducing valve 18.
Is controlled. Specifically, hydraulic pump 1
By adjusting the tilt amount of the swash plate 4 and reducing the maximum discharge flow rate of the pump, the respective turning operations of the boom 5 and the arm 6 are performed gently, thereby increasing the reliability of the horizontal pulling operation. .

FIG. 8 is a circuit diagram showing an arm cylinder control device according to a second embodiment of the present invention. In the following description, the same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between the arm cylinder control device and the first embodiment is that the arm cylinder control device is connected to a pipe line 32 that connects the return oil outlet port 30b of the arm pilot switching valve 30 to the oil tank 22 when the arm is pulled. In addition, a meter-out spool valve 31 that can be switched from an oil passage shutoff position (oil passage restriction position) to an oil passage opening position nu is provided. When the arm pilot switching valve 30 is switched to the arm pull position H, the conduit 32 communicates with the oil tank 22 via the tank communication oil passage 30c and the conduit 30d in the arm position. .

In the second embodiment, the boom raising and the
When the arm retraction is operated simultaneously, the arm cylinder
6a rod side oil chamber 6a₁ Amount of return oil passage opening from
(Opening area) is metered out of the arm spool 30a.
Opening (the opening area is A_c1And for meter-out
Meter-out opening of spool 31b (the opening area is A
_c2To be set). Its total
The expression for obtaining the sum is the same as Expression 1 described above.

Next, the operation of the arm cylinder control device having the configuration of the second embodiment will be described. At the time of arm retraction alone operation, as in the first embodiment,
The arm pilot switching valve 30 is switched from the neutral position to the arm retracted position H, and the meter-out spool valve 31 is switched from the oil passage cutoff position to the oil passage opening position N. In this case, the meter-out spool 31b of the meter-out spool valve 31 moves promptly and in proportion to the amount of arm pulling operation of the arm operating lever 24, so that a highly responsive arm pulling operation can be effectively and effectively performed. It can be done reliably.

Next, when the boom raising and the arm pulling are simultaneously operated, the meter-out spool valve 31 operates in conjunction with the arm pilot switching valve 30 and operates the meter as in the first embodiment. Out spool 3
1b operates in proportion to the amount of arm pulling operation of the arm operating lever 12a. However, when the boom raising and arm retracting operations are performed simultaneously, the meter-out spool 31b of the meter-out spool 31b is operated as compared with the case where the arm retracting operation is performed alone. The operation becomes slow. That is, the controller 21 as the switching operation control means delays the movement of the meter-out spool 31b when the arm operation rises, whereby the arm pulling operation is performed gently. Therefore, the operator can easily and reliably perform the horizontal pulling operation. The meter-out opening of the meter-out spool 31b is changed according to the boom raising operation amount of the boom operation lever 13a, so that the meter-out spool 3
The point that the responsiveness of 1b becomes agile according to the boom raising operation amount is the same as in the first embodiment.

Therefore, the second embodiment can basically fulfill the same function as the first embodiment.

FIG. 9 is a circuit diagram showing an arm cylinder control device according to a third embodiment of the present invention. In the figure, reference numeral 40 denotes an arm pilot switching valve as a directional switching valve for controlling the arm cylinder 6a, 40L and 40R denote left and right pilot ports of the arm pilot switching valve 40, and 40a denotes an arm pilot switching valve 40 (not shown).
Arm spool which is a main spool of the present invention, 41 is a meter-out spool valve which is an example of a responsiveness change spool valve, 41R is a pilot port of the meter-out spool valve 41, and 41a is inside the meter-out spool valve 41 not shown. This is a meter-out spool for changing responsiveness.

The difference between the arm cylinder control device according to the third embodiment and the above-described embodiment is that the return oil outlet port 4 at the time of the arm pulling operation of the arm pilot switching valve 40 is provided.
0b and the oil tank 22 are provided with a meter-out spool valve 41 which can be switched from an oil passage cutoff position (oil passage restriction position) to an oil passage position with a throttle portion 41b.

[0053] In this embodiment, when the boom raising and arm pulling are operated simultaneously, the passage opening of the return oil from the rod side oil chamber 6a ₁ of the arm cylinder 6a (the opening area), meter-out arm spool 40a The opening (the opening area is defined as Ac1) and the meter-out opening of the meter-out spool 41a (the opening area is defined as Ac2) are set as the total. The sum A _total
An example of the equation for obtaining is shown below. A _total = Ac1 + Ac2

Next, the operation of the arm cylinder control device according to the third embodiment having the above configuration will be described.
When the arm is retracted alone, the arm pilot switching valve 40 is switched from the neutral position to the arm pulling position as in the first embodiment, and the meter-out valve is switched in conjunction with the switching operation of the arm pilot switching valve 40. The spool valve 41 is switched from the shutoff oil passage position e to the oil passage position w with the throttle. In this case, since the meter-out spool 41a of the meter-out spool valve 41 operates promptly in proportion to the arm pulling operation amount of the arm operating lever 12a, the arm pulling operation with high responsiveness is effectively and effectively performed. It can be done reliably.

When the boom raising and the arm retraction are simultaneously performed, the meter-out spool valve 41 operates in conjunction with the arm pilot switching valve 40, and operates similarly to the operation of the first embodiment. The operating spool 41a operates in proportion to the arm pulling operation amount of the arm operating lever 12a, but the controller 21 as the switching operation control means operates the meter-out spool 41a more than the case of the arm pulling alone operation. Is controlled to be slow. That is, in the arm operation, the movement of the meter-out spool 41a is controlled so as to be delayed at the time of rising, whereby the arm pulling operation is performed gently.

Since the meter-out opening of the meter-out spool 41a is changed according to the boom raising operation amount of the boom operation lever 13a, the responsiveness of the meter-out spool 41a increases as the boom raising operation amount increases. Being agile, you can do horizontal pulling easier and faster. As described above, the third embodiment can basically fulfill the same function as the first embodiment.

The oil passage switching valve of the present invention is not limited to the above embodiment, and the passage to the pressure oil introduction portion of the directional control valve for the arm is opened beforehand at the neutral position (oil passage restriction position).
In addition, the passage may be narrowed down, and the spool valve may be configured to open the passage at the time of switching.

[0058]

According to the present invention, when the arm retraction is operated alone, a highly responsive arm retraction operation can be realized. For example, the arm is quickly operated to remove the soil from the bucket. Instantaneous operation speed can be increased.

When the raising of the boom and the retraction of the arm are simultaneously operated, the switching operation control means performs control so that a delay occurs at the time of the rise of the arm operation, and performs the arm retraction operation slowly. Therefore, the operator can easily and reliably perform the horizontal pulling operation without paying attention to the fact that the claws of the bucket bite into the ground.

Further, the switching operation speed of the oil passage switching valve is changed according to the boom raising operation amount of the boom operation lever. Therefore, the response characteristic of the arm becomes more agile as the boom raising operation amount becomes larger, The operability of the pulling operation is further improved.

When the raising of the boom and the retraction of the arm are simultaneously operated, the discharge flow rate of the hydraulic pump is restricted, so that the turning operation of the boom and the arm is performed gently, and the horizontal pulling operation is more reliably performed. It has the advantage of being carried out.

According to the present invention, since the response is made agile after a lapse of a certain time after the horizontal pulling is started or in accordance with the magnitude of the boom operation amount, the wiping is completed when the horizontal pulling is completed. Can be done. That is, in performing a series of operations of shifting from the start of horizontal pulling to the continuous horizontal pulling operation and further performing earth removal as a closing of the work, each operation can be controlled to a required speed. Therefore, it is possible to obtain an agile operation, which cannot be realized by the conventional technology, in which the arm speed is simply reduced at the time of the simultaneous operation.

[Brief description of the drawings]

FIG. 1 is a side view showing a hydraulic excavator equipped with a hydraulic control device of the present invention (in a state where a horizontal pulling operation is being performed).

FIG. 2 is a circuit diagram showing an arm cylinder control device according to the first embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a pilot pressure P ₁ and a time t during an arm pulling operation.

4 is a graph showing the relationship between the pilot pressure P ₂ and the time t which acts on the spool of the oil passage switching valve during the arm pulling alone operation.

FIG. 5 shows a pilot pressure P ₂ acting on the spool of the oil passage switching valve during simultaneous operation of raising the boom and retracting the arm.
7 is a graph showing the relationship between 'and time t.

FIG. 6 shows an arm pulling meter-out opening area Atotal and a time t by the arm spool and the switching spool shown in FIG. 2;
6 is a graph showing a relationship with the graph.

FIG. 7 is an explanatory diagram illustrating a response state of an oil passage switching valve that operates according to a boom raising operation amount according to the present invention.

FIG. 8 is a circuit diagram showing a configuration of an arm cylinder control device according to a second embodiment of the present invention.

FIG. 9 is a circuit diagram showing a configuration of an arm cylinder control device according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a configuration of a hydraulic control device mounted on a conventional hydraulic excavator.

[Description of Signs] 1 Hydraulic excavator 4 Work attachment 5 Boom 5a Boom cylinder 6 Arm 6a Arm cylinder 10 Pilot switching valve for arm 10a Arm spool 10b Return oil outlet port at arm pull operation 11 Oil passage switching spool valve 11a Oil passage switching spool 12a Arm operating lever 13a Boom operating lever 14 Hydraulic pump 17, 18 Electromagnetic proportional pressure reducing valve 19, 20 Pressure sensor 21 Controller

Claims (9)

[Claims] 1. A hydraulic actuator for an arm and a boom; a directional control valve for an arm and a directional control valve for a boom for controlling the hydraulic actuator for the arm and the boom; and a hydraulic oil for each directional control valve. A hydraulic pump to be supplied; an operating body for operating the arm and the boom; a detecting means for detecting an operating state of the operating body for the arm and the operating body for the boom; an oil outlet port and an oil tank of the directional control valve for the arm And an oil passage switching valve that switches from an oil passage restricted position to an oil passage open position in conjunction with the arm direction control valve, and the arm and boom operating bodies are simultaneously operated. The switching operation speed of the oil passage switching valve is made slower than the single operation of the arm operating body in accordance with the operation state detected by the detection means in the state in which the operation is performed. A hydraulic control device for a hydraulic shovel, comprising: switching valve control means. 2. The hydraulic control device according to claim 1, wherein the oil passage switching valve operates in proportion to an operation amount of the arm operating body. 3. The switching valve control means, when an arm pulling operation and a boom raising operation are detected simultaneously, delays a switching operation speed of the oil passage switching valve as compared with a single operation of the arm operating body. The hydraulic control device according to claim 1. 4. The responsiveness of the oil passage switching valve according to the amount of operation of the boom operating body in a state where the arm and boom operating bodies are simultaneously operated. The hydraulic control device according to any one of the above. 5. The oil passage switching valve according to claim 1, further comprising a spool valve for switching an oil passage from a shut-off position to a pressure oil introduction portion of the directional control valve for the arm and returning excess oil to an oil tank. The hydraulic control device according to any one of claims 1 to 4. 6. The hydraulic control device according to claim 1, wherein the oil passage switching valve includes a spool valve that switches an oil passage from a shutoff position to an oil tank communication position. 7. The oil passage switching valve comprises a spool valve for switching from a neutral position for sending pressure oil to a pressure oil introduction portion of the arm direction control valve in a state where the passage is narrowed, to an open position for opening the passage. The hydraulic control device according to claim 1, wherein: 8. The hydraulic control device according to claim 1, wherein the oil passage switching valve comprises a spool valve that switches an oil passage from a shut-off position to an oil tank communication position with a throttle. 9. The hydraulic control device according to claim 1, wherein the discharge flow rate of the hydraulic pump is reduced in a state where the operating members for the arm and the boom are simultaneously operated.