JP4155381B2 - Attachment control device for hydraulic excavator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an attachment control device for a hydraulic excavator.
[0002]
[Prior art]
The hydraulic excavator performs excavation work using a bucket attached to the tip of the work machine, and performs various work by attaching various attachments such as a hydraulic breaker and a crusher instead of the bucket. FIG. 1 shows a hydraulic excavator that is equipped with a hydraulic breaker and performs a crushing operation.
The hydraulic excavator 1 is equipped with a hydraulic breaker 10 at the tip of the work machine 4 and performs a crushing operation by pressing the chisel 10b substantially vertically against a crushing object (the ground in the case of FIG. 1). When the object to be crushed is a strong object such as concrete or rock, the boom cylinder 11 is driven to shorten, the boom 8 is lowered, and the working machine 4 is pushed against the ground to lift the front part of the lower traveling body 2, By causing a part of the vehicle body weight to act on the chisel 10b, the crushing force is greatly increased and the working efficiency is increased.
[0003]
FIG. 4 shows a hydraulic circuit according to the prior art.
Discharge sides of a first variable displacement hydraulic pump 21 (hereinafter referred to as a main hydraulic pump 21) and a second variable displacement hydraulic pump 22 (hereinafter referred to as a sub hydraulic pump 22) that rotate using the engine 20 as a drive source. Are connected to pipe lines 23 and 24, respectively, and relief valves 25a and 25b are connected to the pipe lines 23 and 24, respectively.
The pipeline 23 is connected to a boom operation valve 26 and an attachment operation valve 27, and supplies pressure oil discharged from the main hydraulic pump 21 to these operation valves 26 and 27. The boom operation valve 26 is connected to the boom cylinder 11 via secondary side pipes 26A and 26B. The attachment operation valve 27 is connected to a breaker cylinder 10a provided in the hydraulic breaker 10 through a secondary pipe line 27A. A safety valve 28 is connected to the pipe line 27A. A filter 29 is connected to the drain side of the breaker cylinder 10a.
The pipe line 24 is connected to an operation valve (not shown) (for example, a swing operation valve, an arm operation valve, etc.).
[0004]
Further, a pressure reducing valve 30 is connected to the pipe line 24, and a pilot valve 33 of the boom operation lever 32, a pilot valve 35 of the attachment operation pedal 34, and the like are not shown through a pipe line 31 on the secondary side of the pressure reducing valve 30. Pilot pressure is supplied to a pilot valve (for example, a pilot valve for turning operation or a pilot valve for arm operation).
The pilot valve 33 includes pressure reducing units 33a and 33b. The decompression unit 33a is connected to the operation unit 26a of the boom operation valve 26 via the pilot conduit 36A, and the decompression unit 33b is connected to the operation unit 26b of the boom operation valve 26 via the pilot conduit 36B. As shown in FIG. 2, the decompression unit 33a operates the boom lowering drive, and the decompression unit 33b operates the boom raising drive.
The pilot valve 35 includes pressure reducing units 35a and 35b. The decompression unit 35a is connected to the operation unit 27a of the attachment operation valve 27 via the pilot conduit 37A, and the decompression unit 35b is connected to the operation unit 27b of the attachment operation valve 27 via the pilot conduit 37B. As shown in FIG. 2, the decompression unit 35a performs breaker driving.
[0005]
An electromagnetic switching valve 39 that is switched by a command signal from the controller 58 is connected to the pipeline 31 that supplies the pilot pressure. The output hydraulic pressure from the electromagnetic switching valve 39 is connected to a switching valve 41 interposed on a pipe line 40 that connects the discharge side pipe line 23 of the main hydraulic pump 21 and the discharge side pipe line 24 of the sub hydraulic pump 22. Switching of the switching valve 41 is switched. The controller 58 is connected to the junction / separation switching switch 42, and the controller 58 outputs a switching signal to the electromagnetic switching valve 39 in response to the switching signal of the coupling / separation switching switch 42.
[0006]
As shown in FIG. 1, when performing a composite operation for driving the hydraulic breaker 10 while lowering the boom 8, the boom operation lever 32 is operated to the position A and the attachment operation pedal 34 is operated to the position C which is the full operation position. .
When the boom operation lever 32 is operated to the position A, the pilot pressure from the pressure reducing valve 30 is applied to the operation portion 26a of the boom operating valve 26 via the pilot line 36A by the pressure reducing portion 33a of the pilot valve 33, and the boom operating valve 26 switches from the neutral position n to the position a. When the attachment operation pedal 34 is operated to the position C, the pilot pressure from the pressure reducing valve 30 by the pressure reducing portion 35a of the pilot valve 35 acts on the operation portion 27a of the attachment operating valve 27 via the pilot pipe line 37A. 27 switches from the neutral position n to the position a. As a result, the pressure oil discharged from the main hydraulic pump 21 is supplied to the head chamber of the boom cylinder 11 via the conduit 26A, the boom 8 is lowered, and is supplied to the breaker cylinder 10a via the conduit 27A. To drive.
[0007]
[Problems to be solved by the invention]
However, the prior art has the following problems.
That is, since the hydraulic breaker 10 is provided with the safety valve 28, the hydraulic pressure in the conduit 27 </ b> A is suppressed below the set pressure of the safety valve 28, and the attachment operation valve 27 is operated when the attachment operation valve 27 is operated to the position a. The oil pressure of the primary line 23 of the valve 27 is also suppressed by the set pressure of the safety valve 28. For this reason, the hydraulic pressure of the pressure oil supplied to the boom cylinder 11 does not increase, and the work implement 4 cannot be stretched until the front portion of the upper swing body 2 is lifted. Thereby, the crushing operation using the weight of the vehicle body cannot be performed.
[0008]
Even when the boom lowering drive is possible, if the boom lowering force is increased, a large amount of pressure oil flows toward the breaker cylinder 10a having a light load, and the driving speed of the boom 8 is reduced. Even when the discharge oil of the auxiliary hydraulic pump 22 is joined to the pipe line 23 via the switching valve 41 by switching the joining / dividing switch 42 and opening the switching valve 41, the flow rate increases. Therefore, although the boom driving speed is increased, the hydraulic pressure of the pipe line 23 does not increase, so the boom 8 cannot be stretched until the front part of the upper swing body 2 is lifted.
[0009]
The present invention has been made paying attention to the above problem, and even when the attachment and the work implement are operated simultaneously, the pressure of the work implement actuator is not affected by the set pressure of the safety valve of the attachment. An object of the present invention is to provide an attachment control device for a hydraulic excavator capable of supplying oil.
[0010]
[Means, actions and effects for solving the problems]
In order to achieve the above object, the pilot pressure corresponding to the operation amount of the work implement operating means is received and switched by the operation section via the first pilot pipe, and the discharge oil from the hydraulic pump is changed to the hydraulic pressure of the work implement. A pilot pressure corresponding to the operation amount of the first operation valve to be supplied to the actuator and the attachment operation means is received and switched to the operation unit via the second pilot pipe, and the discharge oil from the hydraulic pump is changed to the hydraulic pressure of the attachment. In an attachment control device for a hydraulic excavator provided with a second operation valve for supplying to an actuator, an operation detection means for detecting that the work implement operation means has been operated, and an electromagnetic wave disposed in the second pilot pipeline A predetermined current value for reducing the pilot pressure to the electromagnetic control valve when it is detected that the work machine operating means is operated by a signal from the control valve and the operation detecting means It is characterized in that an output control device.
Further, the predetermined current value output from the control device to the electromagnetic control valve is variable.
Furthermore, the hydraulic pump is a main hydraulic pump, at least one sub hydraulic pump that discharges pressure oil that supports the hydraulic circuit of the first operating valve and the second operating valve, a discharge side pipe of the main hydraulic pump, A switching valve arranged on a pipe connecting the discharge side pipe of the sub-hydraulic pump and switching the opening and closing of the circuit; and the control device is operated by the work machine operating means according to a signal from the operation detecting means When it is detected that this has been detected, a command signal for opening the switching valve is output.
[0011]
That is, when the work implement operating means is operated, the pilot pressure to the attachment operation valve is reduced by the electromagnetic control valve, so even if the attachment operation means is fully operated, the opening amount of the attachment operation valve Is squeezed. As a result, even if a safety valve is provided on the attachment, the hydraulic pressure on the primary side of the operation valve for attachment should be higher than the hydraulic pressure on the attachment side (secondary side) that is restricted by the set pressure of the safety valve. Can do. Therefore, it becomes possible to supply the hydraulic pressure that has become high pressure to the hydraulic actuator of the work implement via the operation valve for the work implement, thereby increasing the driving force of the work implement and improving the work capability. .
In addition, since the pressure reduction level of the pilot pressure to the operation valve for the attachment can be made variable, the attachment for the attachment can be increased so that the driving force of the work implement can be increased even for attachments with different specifications of the set pressure of the safety valve. The opening amount of the operation valve can be changed. That is, it is possible to easily cope with attachments having different set pressure specifications.
Furthermore, when the work implement operating means is operated, the oil discharged from the auxiliary hydraulic pump is merged, so that the amount of oil to the work implement can be ensured and work efficiency can be improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a side view showing a crushing operation using a hydraulic excavator.
The excavator 1 includes a lower traveling body 2, an upper revolving body 3 that is pivotably attached to the lower traveling body 2, and a work machine 4 that is attached to the front portion of the upper revolving body 3. . The work machine 4 includes a boom 8 in which a base end portion is mounted so as to be able to be lifted and raised with respect to the upper swing body 3 at a substantially central front portion of the upper swing body 3, and a base end portion is rotatably mounted on the distal end of the boom 8. The hydraulic breaker 10 is attached to the distal end portion of the arm 9 so as to be rotatable. The work machine 4 further includes a boom cylinder 11 interposed between the upper swing body 3 and the boom 8, an arm cylinder 12 interposed between the boom 8 and the arm 9, an arm 9 and a hydraulic breaker 10. The working machine 4 is driven by the expansion / contraction drive of the hydraulic cylinders 11, 12, 13.
[0013]
FIG. 2 shows a hydraulic circuit according to the present embodiment. Note that the same components as those in FIG. 4 are denoted by the same reference numerals and description thereof is omitted.
A pressure switch 43 is attached to the pilot line 36A that connects the pressure reducing portion 33a on the boom lowering side of the pilot valve 33 and the operation portion 26a of the boom operation valve 26, and transmits a detection signal to the controller 38.
An electromagnetic proportional control valve 44 that is driven by a command signal from the controller 38 is mounted on the pilot line 37A that connects the pressure reducing unit 35a on the breaker drive side of the pilot valve 35 and the operation unit 27a of the attachment operation valve 27. .
The controller 38 is further connected to a mode switch 45 for switching on / off of the breaker mode and an output setting unit 46 for setting an output current value to the electromagnetic proportional control valve 44.
When a bucket, a crusher, or the like is attached as a work attachment and the breaker mode is off, the controller 38 outputs a current that fully opens the electromagnetic proportional control valve 44 to the electromagnetic proportional control valve 44. When the hydraulic breaker 10 is installed and the breaker mode is selected, when the boom lowering operation is detected by the detection signal from the pressure switch 43, the controller 38 outputs the output current set in the output setting unit 46 to the electromagnetic proportional control valve 44. Output to.
[0014]
Next, the operation of the above configuration will be described.
First, when the boom cylinder 11 is driven to be shortened, when the boom operation lever 32 is operated to the position A, the pilot pressure from the pressure reducing valve 30 is guided to the pressure reducing portion 33a of the pilot valve 33 via the pipe line 31. The pilot pressure of the pressure reducing portion 33a is controlled by the communication between the input port and the output port of the pressure reducing portion 33a against the spring force that constantly biases the input port and the output port of 33a in a disconnected state. It acts on the lower side operation portion 26a of the boom operation valve 26 via the pipeline 36A, and the boom operation valve 26 is switched from the neutral position n to the position a. Thereby, the discharge oil from the main hydraulic pump 21 flows into the head chamber of the boom cylinder 11 through the pipe line 26A. For this reason, the return oil from the bottom chamber of the boom cylinder 11 is drained to the tank via the boom operation valve 26, and the boom cylinder 11 is driven to be shortened.
When the boom cylinder 11 is driven to extend, the boom cylinder 11 can be driven to extend in the same manner as described above by operating the boom operation lever 32 to the position B. Further, by operating a pilot valve (for example, a pilot valve for turning operation, a pilot valve for arm operation, etc.) of an operating means (not shown), the corresponding hydraulic actuators are similarly driven (extension / retraction driving or turning driving). be able to.
For example, when the boom operation lever 32 is operated to halfway between the neutral position of the lever and the position A (half operation), the pilot pressure from the pipeline 31 is reduced according to the lever operation amount by the pressure reducing unit 33a. It acts on the lower side operation portion 26a of the boom operation valve 26 via the pilot line 36A, and the boom operation valve 26 is switched to an intermediate position between the neutral position n and the position a in accordance with the lever operation amount, to the line 26A. Therefore, the boom 8 has a driving speed corresponding to the lever operation amount.
[0015]
Even when the hydraulic breaker 10 is driven, by operating the attachment operation pedal 34 to the position C in the drawing, which is the full operation position, the pilot pressure is passed through the pilot line 37A of the pressure reducing unit 35a as described above. Acting on the operation portion 27a of the attachment operation valve 27, the attachment operation valve 27 is switched from the neutral position n to the position a. (Because the boom operation lever 32 is in the neutral position and the pressure switch 43 is OFF, the controller 38 outputs a full-open command current to the electromagnetic proportional control valve 44, so the pilot pressure is reduced by the electromagnetic proportional control valve 44. Thus, the pressure oil discharged from the main hydraulic pump 21 is supplied to the breaker cylinder 10a via the pipe line 27A, and the hydraulic breaker 10 is driven. At this time, due to the action of the safety valve 28, the hydraulic pressure in the pipe line 27 </ b> A is limited to be equal to or lower than the set pressure of the safety valve 28.
Since the hydraulic breaker 10 of the work attachment in this embodiment is a single-action single-acting actuator, it can be driven only by switching the neutral position n and the position a of the attachment operation valve 27, and the position b of the attachment operation valve 27 can be driven. Switching to is not necessary. Therefore, when the hydraulic breaker 10 is attached to the work machine 4 as an attachment, a stopper 47 is provided on the attachment operation pedal 34 so that the attachment operation pedal 34 does not tilt in the direction of arrow D in the figure.
[0016]
Next, the operation in the combined operation of the boom lowering drive and the breaker drive will be described.
When crushing the ground using the hydraulic breaker 10, in order to increase the crushing force when the crushing force of the hydraulic breaker 10 alone is insufficient, the boom 8 is driven downward as shown in FIG. The lower traveling body 2 is stretched until the front part is lifted, and a part of the body weight of the hydraulic excavator 1 is applied to the ground via the chisel 10b of the hydraulic breaker 10, thereby increasing the crushing force and performing the work. That is, it is a combined operation of boom lowering drive and breaker drive.
[0017]
In the breaker mode, when the boom operating lever 32 is operated to the boom lowering position A and at the same time the attachment operating pedal 34 is operated to the position C, the boom operating valve 26 is neutralized by the pilot pressure from the pressure reducing portion 33a of the pilot valve 33. Switching from position n to position a. Further, the pressure switch 43 attached to the pilot pipe line 36A is turned on by the pilot pressure from the pressure reducing portion 33a of the pilot valve 33, and it is detected that the boom 8 has been lowered. When the boom lowering operation is performed in the breaker mode, the controller 38 outputs a command current value corresponding to the set value of the output setter 46 to the electromagnetic proportional control valve 44. For this reason, by operating the attachment operation pedal 34, the pilot pressure from the pressure reducing portion 35a of the pilot valve 35 is reduced by the electromagnetic proportional control valve 44 attached to the pilot line 37A for guiding the pilot pressure, and the attachment operation valve 27 The attachment operation valve 27 is switched to an intermediate position between the neutral position n and the position a. That is, the opening amount of the attachment operation valve 27 is reduced by reducing the pilot pressure by the electromagnetic proportional control valve 44.
The pressure oil discharged from the main hydraulic pump 21 is depressurized by the attachment operation valve 27 and supplied to the breaker cylinder 10a via the pipe line 27A, and the hydraulic breaker 10 is driven. At this time, the hydraulic pressure of the pipe line 27A is limited by the safety valve 28, but the hydraulic pressure of the pipe line 23 on the primary side of the attachment operation valve 27 is made higher than the hydraulic pressure of the pipe line 27A due to the throttle effect of the attachment operation valve 27. be able to.
[0018]
Therefore, the pressure oil discharged from the main hydraulic pump 21 can be made higher than the set pressure of the safety valve 28 and supplied to the boom cylinder 11 via the boom operation valve 26 without being affected by the safety valve 28. As a result, the driving force of the boom cylinder 11 is increased, and the boom 8 can be driven in the downward direction to be stretched until the front portion of the lower traveling body 2 is lifted, thereby obtaining a large crushing force using the weight of the vehicle body. .
Further, the throttle effect of the attachment operation valve 27 can reduce the flow rate of the pressure oil to the hydraulic breaker 10 and increase the flow rate of the pressure oil to the boom cylinder 11, so that the drive speed of the boom 8 can be ensured.
Further, it is not necessary to perform the half operation of the attachment operation pedal 34 as in the prior art, and the operation is simplified because the full operation is sufficient.
[0019]
The above embodiment is an example in which the boom 8 and the hydraulic breaker 10 are driven only by the oil discharged from the main hydraulic pump 21, but the controller 38 detects when the boom lowering operation is detected by a signal from the pressure switch 43. The electromagnetic switching valve 39 can be set to transmit a “merge” command current, whereby the electromagnetic switching valve 39 is switched and the switching valve 41 is set to “open”, so that the discharge from the auxiliary hydraulic pump is performed. Oil can be supplied to the conduit 23. Thus, even when the boom lowering, driving and breaker driving are performed simultaneously in the breaker mode, a sufficient flow rate of the pressure oil to the boom cylinder 11 can be ensured, and work efficiency can be increased.
Since the output setter 46 is provided so that the command current value to the electromagnetic proportional control valve 44 is variable, even if the set pressure of the safety valve 28 differs depending on the specifications of the breaker 10, the hydraulic breaker 10 side and the boom cylinder 11 side The command current to the electromagnetic proportional control valve 44 that provides the opening amount of the attachment operation valve 27 so that the flow rate balance of the pressure oil and the hydraulic pressure of the pipe line 23 on the primary side of the operation valves 26 and 27 become suitable values. It is possible to set a value. Thereby, even if the specifications of the hydraulic breaker 10 are different, it is possible to obtain a breaker working device having a good flow rate balance and a large driving force of the boom cylinder 11 correspondingly.
[0020]
When a work is performed with a crusher or a gripper attached as an attachment, the controller 38 sends a command to reduce the pressure even when the boom is lowered by turning off the breaker mode with the mode switch 45. Since it is not output to the proportional control valve 44 and the electromagnetic proportional control valve 44 is fully opened, the pilot pressure from the pilot valve 35 acts on the attachment operation valve 27 without being reduced, and the normal operation can be performed.
[0021]
In addition, this invention is not limited to the said embodiment.
For example, in the embodiment, the example in which the pilot pressure to the attachment operation valve 27 is reduced during the boom lowering operation has been described. However, as shown in FIG. The present invention can also be applied when performing the above. In this case, in order to secure a large driving force for extending the arm cylinder 12 and improve the crushing capability, the pilot pressure to the attachment operation valve 27 is reduced when the extension operation of the arm cylinder 12 is detected. do it.
In addition, although the example of the system having two hydraulic pumps has been described, the present invention may be applied to a system having only one hydraulic pump, or may be applied to a system having a main hydraulic pump and a plurality of sub hydraulic pumps. Of course you can.
The hydraulic circuit is not limited to the embodiment, and the switching valve 41 may be replaced with an electromagnetic one, and the pilot pressure is obtained by the pressure reducing valve 30, but a pilot pump may be used.
[0022]
As described above, according to the present invention, when the boom lowering operation is performed, the pilot pressure to the attachment operation valve is reduced by the electromagnetic proportional control valve provided in the pilot pipe line. Even in the case of full operation, the opening amount of the attachment operation valve is reduced. For this reason, the primary side hydraulic pressure of the attachment operation valve can be made high without being restricted by the set pressure of the safety valve provided in the hydraulic breaker, and the boom cylinder can be driven by this high hydraulic pressure. Thereby, since the driving force of the boom cylinder can be increased, the boom can be driven in the lowering direction until the front part of the vehicle body is lifted, and a large crushing force utilizing the vehicle body weight can be obtained.
[Brief description of the drawings]
FIG. 1 is a side view showing a state of a hydraulic excavator performing a crushing operation.
FIG. 2 is a hydraulic circuit diagram according to the embodiment.
FIG. 3 is a side view showing a state of a hydraulic excavator performing another form of crushing work.
FIG. 4 is a hydraulic circuit diagram of the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Hydraulic excavator, 2 ... Lower traveling body, 4 ... Working machine, 8 ... Boom, 9 ... Arm, 10 ... Hydraulic breaker, 10a ... Breaker cylinder, 11 ... Boom cylinder, 12 ... Arm cylinder, 21, 22 ... Hydraulic pump , 23, 24, 26A, 26B, 27A, 31, 40 ... conduit, 26 ... boom operation valve, 26a, 26b, 27a, 27b ... operation unit, 27 ... attachment operation valve, 28 ... safety valve, 32 ... boom operation lever , 33, 35 ... pilot valve, 34 ... attachment operation pedal, 36A, 36B, 37A, 37B ... pilot line, 38 ... controller, 41 ... switching valve, 43 ... pressure switch, 44 ... electromagnetic proportional control valve, 46 ... output Setting device.

Claims (3)

A pilot pressure corresponding to the operation amount of the work implement operating means is received and switched by the operation section via the first pilot pipe, and the first operation valve that supplies the oil discharged from the hydraulic pump to the hydraulic actuator of the work implement is switched. When,
A pilot pressure corresponding to the amount of operation of the attachment operating means is received and switched by the operating portion via the second pilot line, and a second operating valve for supplying the discharge oil from the hydraulic pump to the hydraulic actuator of the attachment is provided. In the attachment control device of the hydraulic excavator provided,
Operation detecting means for detecting that the work implement operating means has been operated; and
An electromagnetic control valve disposed in the second pilot pipeline;
A hydraulic system comprising: a control device that outputs a predetermined current value for reducing a pilot pressure to the electromagnetic control valve when it is detected that a work implement operating means is operated by a signal from an operation detecting means; Excavator attachment control device. The attachment control device for a hydraulic excavator according to claim 1,
The attachment control device for a hydraulic excavator, wherein a predetermined current value output from the control device to the electromagnetic control valve is variable. The attachment control device for a hydraulic excavator according to claim 1,
The hydraulic pump is a main hydraulic pump,
At least one sub-hydraulic pump that discharges pressure oil that supports the hydraulic circuit of the first operating valve and the second operating valve;
A switching valve that is disposed in a pipe connecting the discharge side pipe of the main hydraulic pump and the discharge side pipe of the sub hydraulic pump, and that switches between opening and closing the circuit;
The control device outputs a command signal for opening the switching valve when it is detected that the work implement operating means is operated by a signal from the operation detecting means. Control device.

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