JPH11209074A - Hydraulic excavator having crane work mode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To slowly move a hydraulic actuator by providing a crane work switch and a delivery reducing means to reduce a maximum delivery of a variable displacement hydraulic pump when this is turned on in a hydraulic shovel having a crane work mode. SOLUTION: When a crane work switch 30 operated by an operator is turned on, an electric current is carried to a control pressure output valve 40b of a delivery reducing means 40 to outpout control pressure from a solenoid proportional pressure reducing valve of the control pressure output valve 40b. Then, this control pressure is outputted to a signal oil passage by being selected by a shuttle valve 40a to regulate a maximum delivery of a variable diaplacement hydraulic pump 14. At this time, when a detecting signal is outputted from a work range detecting means 51, a solenoid proportional pressure reducing valve of a pilot oil control valve 50a is excited. Therefore, pilot oil is discharged to a drain by being reduced by the pilot oil control valve 50a, so that extending directional actuation of a boom cylinder 8d is reduced and stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic excavator having a crane operation mode.

[0002]

2. Description of the Related Art Hydraulic excavators having a working arm are generally used for various works other than excavation work for earth and sand. With reference to FIG. 6, a hydraulic excavator that performs a crane operation by providing a hanging hook on a working arm will be described. A hydraulic excavator, generally designated by the reference numeral 2, comprises a lower traveling body 4, an upper revolving body 6 mounted on the lower traveling body 4 so as to be pivotable about a vertical axis, and a vertically swayable swinging member. And a hook 10 attached to the tip of the working arm 8
And The work arm 8 includes a boom 8a attached to the upper swing body 6 so as to be vertically swingable, and a boom 8a.
8 attached to the tip of the arm so that it can swing up and down
b, and a bucket 8c attached to the tip of the arm 8b so as to be vertically swingable. The hook 10
For example, it is attached to the tip of the arm 8b, the bucket 8c, or the bucket linkage 8f connected to the bucket 8c. The hydraulic excavator 2 is a hydraulic actuator, a swing motor 5 interposed between the lower traveling body 4 and the upper swing body 6, a boom cylinder 8d, a boom 8a interposed between the upper swing body 6 and the boom 8a. And arm 8b
Arm cylinder 8e and arm 8 interposed between
and a bucket cylinder 8g interposed between the bucket b and the bucket 8c.

The crane operation is performed by suspending a suspended load 12 on a hook 10 by appropriately operating a hydraulic actuator. At this time, the bucket 8c is positioned at the end of the swing stroke by extending the bucket cylinder 8g and swinging as shown by an arrow 9. This prevents a hanging tool such as a sling wire rope from being damaged by the teeth (claws) or edges (blades) of the bucket 8c, and fixes the position of the bucket 8c to fix the center of gravity of the bucket 8c. In addition, it is possible to accurately measure the suspension load by the suspension load measuring means (not shown).

[0004]

Continuing the description with reference to FIG. 6, the conventional crane operation using the hydraulic excavator 2 having the above-described configuration has the following problems to be solved. That is,

(1) Operating speed of hydraulic actuator: The hydraulic actuator such as the boom cylinder 8d of the hydraulic shovel 2 is set to operate as quickly as possible with a large amount of oil so that excavation work, loading work, and the like can be performed efficiently. Have been. On the other hand, in the crane operation, it is necessary to slowly move the hydraulic actuator so that the suspended load 12 does not shake and the suspended load 12 can be properly placed at a predetermined position. For this purpose, in the crane operation, the operator finely operates the operation lever of the hydraulic actuator, reduces the amount of oil flowing to the hydraulic actuator, and moves the hydraulic actuator slowly. When the operating lever is operated greatly, the operating speed of the hydraulic actuator increases, the suspended load 12 swings, and the posture of the hydraulic shovel 2 becomes unstable. Therefore, the crane operation by the hydraulic excavator 2 largely depends on the lever operation of the operator, and the burden on the operator is large.

(2) Reaction due to stoppage of the hydraulic actuator: In the crane operation, the inclination of the road surface 3 on which the hydraulic excavator 2 is located, the turning position of the upper revolving unit 6 with respect to the lower traveling unit 4, the swinging position of the working arm 8, A working range that defines the working range of the working arm 8 is set so that the posture of the excavator 2 is not unstable due to the load of the suspended load 12 or the like. For this reason, during the operation, the operator informs the user of the posture of the excavator 2 or the fact that the working arm 8 has entered the limit working range (a range for giving a notice of departure from the working range) from the working position detecting means (not shown). The hydraulic actuator that is moving the working arm 8 in the direction of the limit working range is stopped based on the notified warning signal. However,
When the operating hydraulic actuator is suddenly stopped, the suspended load 12 swings due to the reaction of the hydraulic actuator suddenly stopping, and the hydraulic shovel 2 is likely to be in an unstable posture due to the reaction.

(3) Bucket position: The operator positions the bucket 8c at the swing stroke end of the bucket 8c so as not to obstruct the hook 10, the suspended load 12, and the like, and to accurately measure the suspended load. . However, when the operator unconsciously touches the bucket cylinder operating lever, the bucket 8c moves. Then, it is troublesome to always pay close attention to the position of the bucket 8c during the crane operation and perform the position correcting operation.

The present invention has been made in view of the above-mentioned facts, and its technical problem is that when a crane operation is performed by a hydraulic shovel, (1) the hydraulic actuator can be operated without finely operating the operation lever of the hydraulic actuator. To move slowly,
The amount of oil discharged from the pump to the hydraulic actuator is restricted and reduced. (2) When the working arm enters the limit working range during operation of the hydraulic actuator, the movement of the hydraulic actuator moving the working arm in the direction of the limit working range is decelerated and stopped. (3) When the bucket is moved to the end of the swing stroke, the bucket is stopped and held at that position, and the bucket cylinder does not operate even if the bucket operating lever is operated, so that the bucket does not swing.

[0009]

According to the present invention, as a hydraulic shovel for solving the above technical problem (1), a work arm provided to be swingable on an upper swing body is provided with a variable displacement hydraulic pump. In a hydraulic excavator that performs a crane operation by selectively supplying discharge oil to a hydraulic actuator by a directional control valve and operating the same, the hydraulic excavator includes a crane operation switch and the variable displacement hydraulic pressure switch when the crane operation switch is turned on. A hydraulic excavator having a crane operation mode is provided, comprising: a discharge oil amount reducing means for reducing a maximum discharge oil amount of a pump.

When the crane operation switch is turned on when performing the crane operation, the discharge oil amount of the variable displacement hydraulic pump is reduced by the discharge oil amount reduction means, and the operation lever of the hydraulic actuator does not need to be finely operated. Even hydraulic actuators move slowly.

As a hydraulic excavator that solves the above technical problem (2), a working arm swingably provided on an upper revolving unit is selected from a discharge oil of a variable displacement hydraulic pump as a hydraulic actuator by a direction control valve. In a hydraulic shovel for supplying and operating a crane operation, the hydraulic shovel comprises a crane operation switch, and when the operation arm enters a predetermined limit operation range when the crane operation switch is turned on, the operation arm is moved. An actuator deceleration stop means for stopping the hydraulic actuator moving in the direction of the limit operation range while decelerating the hydraulic actuator is provided, and a hydraulic excavator having a crane operation mode is provided.

When the crane operation switch is turned on when performing the crane operation, when the operation arm enters the limit operation range, the hydraulic actuator moving the operation arm in the direction of the limit operation range is actuated by the actuator deceleration stop means. The movement is slowed down and stopped.

[0013] As a hydraulic excavator that solves the above technical problem (3), a working arm that is swingably provided on an upper revolving unit selects a discharge oil of a variable displacement hydraulic pump as a hydraulic actuator by a direction control valve. In a hydraulic excavator that performs a crane operation by manually supplying and operating a crane operation, the hydraulic excavator is provided with a crane operation switch and a bucket cylinder at a tip end of the operation arm when the crane operation switch is turned on so as to be swingable by a bucket cylinder. And a bucket lock means for fixing the bucket to the end of the swing stroke.

When the crane operation switch is turned on and the bucket is moved to the end of the swing stroke when the crane operation is performed, the bucket is held at that position by the bucket locking means. The cylinder does not work.

As a hydraulic shovel that solves the above technical problems (1), (2) and (3), a working arm slidably provided on an upper revolving unit is provided with a discharge oil of a variable displacement hydraulic pump. In a hydraulic shovel that selectively supplies a hydraulic actuator by a directional control valve to operate and perform a crane operation, the hydraulic shovel includes a crane operation switch,
A discharge oil amount reducing means for reducing a maximum discharge oil amount of the variable displacement hydraulic pump when the crane operation switch is turned on, and when the operation arm enters a predetermined limit operation range, the operation arm is moved to the limit operation range. Actuator deceleration stop means for stopping the hydraulic actuator moving in the direction while decelerating, and bucket lock means for fixing a bucket provided at the tip of the working arm so as to be swingable by a bucket cylinder at a swing stroke end. Has,
A hydraulic excavator having a crane operation mode is provided.

Therefore, when performing a crane operation, when the crane operation switch is turned on, the discharge oil amount of the variable discharge type hydraulic pump is reduced, the hydraulic actuator moves slowly, and when the operation arm enters the limit operation range. The movement of the hydraulic actuator that is moving the work arm in the direction of the limit work range is decelerated and stopped, and when the bucket is moved to the end of the swing stroke, the bucket is held at that position and even if the bucket operation lever is operated Bucket cylinder does not work.

In a preferred embodiment, the discharge oil amount of the variable displacement hydraulic pump is negatively controlled, that is, the circuit pressure of the center bypass oil passage of the directional control valve is transmitted to the variable displacement hydraulic pump via a signal oil passage. Lead to signal pressure,
The discharge oil amount decreasing means is controlled to increase or decrease between a minimum discharge oil amount defined on a high pressure side of the signal pressure and a maximum discharge oil amount defined on a low pressure side of the signal pressure in accordance with the signal pressure. Is
A shuttle valve provided in the signal oil passage; and a control pressure output valve for outputting a control pressure. The shuttle valve compares the circuit pressure with the control pressure, and a higher pressure is applied to the signal oil passage. To the variable displacement hydraulic pump as the signal pressure. Further, the control pressure output valve includes an electromagnetic proportional pressure reducing valve.

Then, a control pressure for reducing the discharge oil amount is selected by the shuttle valve provided in the signal oil passage for guiding the circuit pressure to the variable displacement hydraulic pump, and is guided to the variable displacement hydraulic pump. Therefore, the maximum discharge oil amount is reduced by flowing a control pressure higher than the circuit oil pressure that defines the maximum discharge oil amount. Further, the control pressure is arbitrarily set by an electromagnetic proportional pressure reducing valve.

In a preferred embodiment, the direction control valve is switched by pilot oil, and the actuator deceleration stop means includes a pilot oil control valve for controlling the pilot oil. The pilot oil control valve includes an electromagnetic proportional pressure reducing valve.

Then, the movement of the hydraulic actuator is reduced and stopped by the pilot oil control valve. Also, by changing the pressure setting of the electromagnetic proportional pressure reducing valve, the manner of deceleration until the hydraulic actuator stops can be arbitrarily changed.

In a preferred embodiment, the bucket cylinder is operated by a directional control valve switched by pilot oil, and the bucket lock means includes bucket detection means for detecting a swinging position of the bucket, and bucket detection means. A pilot oil shutoff valve for shutting off the pilot oil when the bucket detects that the bucket is located at the end of the swing stroke and holding the directional control valve at a neutral position.

When the bucket is moved to the swing stroke end and the bucket detecting means detects that the bucket is located at the swing stroke end, the pilot oil of the direction control valve for operating the bucket cylinder is operated by the pilot oil cutoff valve. Is shut off, the directional control valve is held in the neutral position and the bucket is not operated and locked in that position.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a hydraulic excavator having a crane working mode constructed in accordance with the present invention.

Referring to FIG. 1, a hydraulic excavator having a crane operation mode includes a variable displacement hydraulic pump 14, a plurality of hydraulic actuators 16 for moving a working arm 8, and a variable displacement hydraulic pump 14. Directional control valve 17 for selectively supplying oil discharged to the hydraulic actuator 16
And FIG. 1 shows a boom cylinder 8 d and a bucket cylinder 8 f as representatives of the plurality of hydraulic actuators 16. The hydraulic excavator further includes a crane operation switch 3 that is turned on when performing the crane operation.
0, a discharge oil amount reducing means 40 for reducing the maximum discharge oil amount of the variable displacement hydraulic pump 14 when the crane operation switch 30 is on, and the operation arm 8 when the operation arm 8 moves to enter a predetermined limit operation range. Decelerating and stopping means 50 for stopping the hydraulic actuator 16 (the boom cylinder 8d in FIG. 1) which moves the hydraulic actuator 16 in the direction of the limit working range while decelerating, and the swing stroke of the bucket 8c by regulating the operation of the bucket cylinder 8f. And a bucket lock means 60 fixed to the end.

The variable displacement hydraulic pump 14 includes a pump body 14a such as a swash plate type piston pump and a variable displacement mechanism 14b such as a swash plate regulator for changing the discharge oil amount of the pump body 14a based on signal pressure oil from outside. Have. The oil discharged from the variable displacement hydraulic pump 14 is supplied to an oil passage 15
To the direction control valve 17.

The directional control valves 17 are arranged in a plurality corresponding to each of the plurality of hydraulic actuators 16. FIG.
Has a boom control valve 1 for operating a boom cylinder 8d.
8. Bucket control valve 1 for operating bucket cylinder 8f
9 is shown. The boom control valve 18 and the bucket control valve 19 are pilot-operated directional control valves in which the valve spool is stroked by pilot oil and switched. When not operated by the pilot oil, the spool 18a of the boom control valve 18 is held at a neutral position (the state shown in FIG. 1) by centering springs 18b, 18b provided on the spool 18a, and the spool 19a of the bucket control valve 19 is connected to the spool 19a. The centering springs 19b are provided at a neutral position (the state shown in FIG. 1). At this time, the discharge oil guided from the variable displacement hydraulic pump 14 to the directional control valve 17 via the oil passage 15 passes through the center bypass oil passage 17a of the directional control valve 17 and passes through the oil passage 22 connected to the directional control valve 18. Through the tank 23. An orifice 17b is provided downstream of the center bypass oil passage 17a so that a circuit pressure corresponding to the flowing flow rate is generated in the center bypass oil passage 17a. This circuit pressure is guided to the variable displacement mechanism 14 b of the variable displacement hydraulic pump 14 via a signal oil passage 26.

An operating means 20 for switching the operation by flowing pilot oil to the boom control valve 18 includes an operating lever 20a and a pair of pressure reducing valves 20b and 20c for outputting pilot oil of pilot oil pressure corresponding to the operation amount of the operating lever 20a. It has. The pilot oil from the pressure reducing valve 20b is supplied to the oil passage 2
It is guided to one end of the spool 18a of the boom control valve 18 via 0d. The pilot oil from the pressure reducing valve 20c is supplied to the spool 1 of the boom control valve 18 through an oil passage 20e.
8a is led to the other end. Similarly, the bucket control valve 19
The operating means 21 for switching the pilot oil by flowing the pilot oil includes an operating lever 21a and a pair of pressure reducing valves 21b and 21c for outputting pilot oil of pilot oil pressure according to the operation amount of the operating lever 21a. The pilot oil from the pressure reducing valve 21b is guided to the end of the spool 19a of the bucket control valve 19 via the oil passage 21d, and the pilot oil from the pressure reducing valve 21c is guided to the end of the spool 19a via the oil passage 21e.

By operating the operating means 20, the boom control valve 18 is operated.
The flow of the discharge oil from the variable displacement pump 14 when the boom cylinder 8d is extended and contracted by switching the operation of the boom cylinder 8d will be described.
In order to extend the boom cylinder 8d, the oil discharged from the pump 14 flows into the head-side oil chamber 18c of the boom cylinder 8d. For this purpose, the operator operates the operation lever 20a to supply pilot oil having a pressure corresponding to the operation amount from the pressure reducing valve 20c to the oil passage 2.
0e, the spool 18a is stroked against the centering spring 18b according to the pilot oil pressure, and the discharge oil corresponding to the stroke is caused to flow to the head side oil chamber 18c of the boom cylinder 8d. At this time, the discharge oil flowing through the center bypass oil passage 17a of the direction control valve 17 decreases as the flow of the spool 18a to the head-side oil chamber 18c of the boom cylinder 8d increases. When the operation amount of the operation lever 20a is further increased, the oil passage 20e
The pilot oil pressure of the boom control valve 18
Of the spool 18a further strokes, and the amount of oil discharged to the boom cylinder 8d further increases. And oilway 1
The discharge oil flowing through 7a decreases, and when the spool 18a strokes to some extent, there is no flow in the oil passage 17a, and no circuit pressure to the signal oil passage 26 is generated. The hydraulic oil in the rod-side oil chamber 18d of the boom cylinder 8d passes through the switched spool 18a, passes through the return oil passage 17c, flows into the oil passage 22, and flows into the tank 23. When the operation of the operation lever 20a is stopped, the flow of the pilot oil to the boom control valve 18 is stopped, and the oil passage 20e for the pilot oil is opened to the drain, the spool 18a is moved to the centering spring 18b,
It returns to the neutral position by the force of 18b. Then, the flow of the discharge oil to the boom cylinder 8d is stopped, and the extension operation stops. When contracting the boom cylinder 8d, use the pressure reducing valve 2
0b is operated to flow the discharge oil from the pump 14 into the rod-side oil chamber 18d of the boom cylinder 8d.

The flow of oil discharged from the variable displacement pump 14 when the operating means 21 is operated to extend and retract the bucket cylinder 8f will be described. To extend the bucket cylinder 8f, the operating lever 21a is operated to operate the pressure reducing valve 21c.
, The pilot oil having a pressure corresponding to the operation amount is caused to flow through the oil passage 21e, the spool 19a is stroked according to the pilot oil pressure, and the discharge oil corresponding to the stroke is caused to flow to the head side oil chamber 19c of the bucket cylinder 8f. The hydraulic oil in the rod-side oil chamber 19d of the bucket cylinder 8f passes through the switched spool 19a, passes through the return oil passage 17c, and passes through the oil passage 22.
To the tank 23. When the operation of the operation lever 21a is stopped and the supply of the pilot oil is stopped and the drain is opened to the drain, the spool 19a is moved to the centering spring 19b,
Returning to the neutral position by 19b, the flow of the discharge oil to the bucket cylinder 8d is stopped, and the extension operation is stopped. When the bucket cylinder 8f is contracted, the pressure reducing valve 21b is operated to discharge the discharged oil to the rod-side oil chamber 1 of the bucket cylinder 8f.
Flow to 9d.

The crane operation switch 30 is constituted by an on / off switch operated by an operator, and is provided at an appropriate place near the driver's seat. When a crane operation is performed, the crane operation switch 30 is turned on, and the power supply 31 is connected to the discharge oil amount reduction unit 40, the actuator deceleration stop unit 50, the bucket lock unit 60, and the like.

The discharge oil amount of the variable displacement hydraulic pump 14 is negatively controlled. That is, the circuit pressure of the center bypass oil passage 17a of the directional control valve 17 is led to the variable displacement hydraulic pump 14 as a signal pressure via the signal oil passage 26, and the signal pressure is increased by the variable displacement mechanism 14b according to the signal pressure. The discharge oil amount is controlled to increase or decrease between a minimum discharge oil amount defined on the side of the side and a maximum discharge oil amount defined on the low pressure side of the signal pressure.

The discharge oil amount reducing means 40 has a shuttle valve 40a provided in the signal oil passage 26 and an electromagnetic proportional pressure reducing valve which is energized when the crane operation switch 30 is turned on and outputs a set control pressure. And a control pressure output valve 40b. The shuttle valve 40a compares the circuit pressure of the center bypass oil passage 17a with the set control pressure from the control pressure output valve 40b, and the higher pressure passes through the signal oil passage 26 and becomes the signal pressure as a variable displacement hydraulic pump. 14
It is led to.

The negative control of the discharge oil amount of the variable displacement hydraulic pump 14 and the operation of the discharge oil amount reducing means 40 will be described with reference to FIG. 1 and FIG. The relationship between the discharge oil amount Q of the variable displacement hydraulic pump 14 and the signal pressure P of the signal oil passage 26 is such that the crane operation switch 30 is off,
That is, when the discharge oil amount reducing means 40 does not operate, the characteristic is controlled as shown by the solid line in FIG. That is, the discharge oil amount Q is determined by the minimum discharge oil amount Q1 defined on the high pressure side P1 and the maximum discharge oil amount Q2 defined on the low pressure side P2 according to the signal pressure P which is the circuit pressure of the center bypass oil passage 17a. Controlled between. The circuit pressure is controlled by the hydraulic actuator 1
When the directional control valve 17 that does not operate the actuator 16 is in the neutral position, the center bypass oil passage 17
The flow of a is maximum, the circuit pressure (signal pressure P) is maximum, and the discharge oil amount Q is minimum. When the direction control valve 17 is switched and the flow in the center bypass oil passage 17a decreases, the circuit pressure (signal pressure P) decreases and the discharge oil amount increases. When the circuit pressure (signal pressure P) becomes minimum, the discharge oil amount Q becomes maximum.

When the crane operation switch 30 is turned on,
The control pressure output valve 40b of the discharge oil amount reducing means 40 is energized, and the electromagnetic pressure reducing valve of the control pressure output valve 40b is moved to the high pressure side P.
Set control pressure Pc lower than 1 and higher than low pressure side P2
Is output, the control pressure Pc higher than the low pressure side pressure P2 defining the maximum discharge oil amount Q2 is selected by the shuttle valve 40a and output to the signal oil passage, and the maximum discharge oil amount of the variable displacement hydraulic pump 14 Is defined as a discharge oil amount Qc smaller than the maximum discharge oil amount Q2 when the discharge oil amount reduction means 40 is not operated.

Continuing with FIG. 1, the actuator deceleration and stopping means 50 operates the directional control valve 17 of the hydraulic actuator 16 for moving the working arm 8 in the direction of the limit working range. Is provided with a pilot oil control valve 50a having an electromagnetic proportional pressure reducing valve. In the present embodiment, a boom cylinder 8d is exemplified as the hydraulic actuator 16 that moves the working arm 8 in the direction of the limit working range. Boom cylinder 8d
When the arm is extended, the working arm 8 moves in the direction of the limit working range. Therefore, a pilot oil control valve 50a is provided in a pilot oil passage 20e that strokes the spool 18a of the boom control valve 18 so as to extend the boom cylinder 8d. When the crane operation switch 30 is ON, the pilot oil control valve 50a outputs an output when the operation range detecting means 51 detects that the operation arm 8 has entered the predetermined limit operation range by the extension operation of the boom cylinder 8d. Based on the signal, the pilot oil pressure that causes the spool 18a of the pilot oil passage 20e to stroke is gradually reduced and drained.

The work range detecting means 51 is based on data from a potentiometer (not shown) provided at the center of swing of the boom 8a, arm 8b, etc. (see FIG. 6).
, Specifically, the position of the hanging hook 10 is calculated by a microcomputer, and the position of the working arm 8 with respect to the working range in which the hanging load is properly handled is detected. When it is detected that the working arm 8 has entered the limit working range just before the working arm 8 deviates from the working range, the detection signal is sent to the actuator deceleration stop means 50.
To the pilot oil control valve 50a.

The operation of the actuator deceleration stop means 50 will be described. When a detection signal is output from the work range detection means 51 when the crane work switch 30 is turned on, the electromagnetic proportional pressure reduction of the pilot oil control valve 50a of the pilot oil passage 20e of the boom operation valve 18 that moves the boom cylinder 8d in the extension direction. The valve 50a is excited. The pilot oil that is causing the spool 18a to stroke against the centering spring 18b is
As a result, the pressure is gradually reduced and the drain is discharged to the drain. The pushing force on the spool 18a is gradually reduced, and the spool 18a is returned to the neutral position. Thus, the operation of the boom cylinder 8d in the extension direction is decelerated and stopped. Further, the boom cylinder 8d is automatically decelerated and stopped by the actuator deceleration stop means 50 without the operator operating the operation means 20. Stopped boom cylinder 8d
Is operated in the contraction direction, or another hydraulic actuator 16 is operated.
To return the working arm 8 to the working range outside the limit working range, the output signal from the working range detecting means 51 is released, and the control of the pilot oil passage by the pilot oil control valve 50a is released.

In FIG. 1, the actuator deceleration stop means 50 stops the movement of the boom cylinder 8d, which is a hydraulic actuator, in the extending direction, but contracts the cylinder in the arm cylinder 8e of another hydraulic actuator. The movement in the direction to be set is set in relation to the form, specifications, work range, and the like of the working arm 8, such as stopping the turning movement in both the left and right directions in the swing motor 5.

Continuing the description with reference to FIG. 1, the bucket lock means 60 includes a bucket detection means 61 for detecting the swinging position of the bucket 8c, and a bucket lock means 60 for detecting the swing position of the bucket 8c. Bucket 8c
Has a pilot oil cutoff valve 62 that operates based on a detection signal located at the end of the swing stroke. The bucket detecting means 61 includes a pressure switch 61a provided in an oil passage 19d connected to the head side oil chamber 19c of the bucket cylinder 8f. The pilot oil cutoff valve 62 is connected to the pilot oil passage 21 d and the oil passage 21 e of the bucket control valve 19.
Is provided with an electromagnetic switching valve 62a. When the pressure switch 61a reaches a specified pressure (for example, the relief pressure of the bucket cylinder 8f when the bucket 8c reaches the swing stroke end), the switch is connected and turned on.
The crane operation switch 30 is connected to a pilot oil shutoff valve 62 via a pressure switch 61a.

Referring to FIG. 3 together with FIG. 1, the operation of the bucket lock means 60 will be described mainly with reference to FIG.

In step S-1, whether the crane operation switch 30 is on or off is determined.

When the crane operation switch 30 is on,
In step S-2, the bucket cylinder 8f is extended to operate the bucket 8c in the direction of the swing stroke end.

In step S-3, it is determined whether the bucket 8c has reached the end of the swing stroke and the pressure switch 61a of the bucket detecting means 61 has been turned on.

Pressure switch 61 of bucket detecting means 61
When a is turned on, in step S-4, the pilot oil cutoff valve 62 is energized and turned on, and the pilot oil passage 2
1d and the oil passage 21e are shut off, and the pilot oil shutoff valve 6
2 is released to the drain, the spool 19a of the bucket control valve 19 is returned to the neutral position, and the pilot oil passage 21d between the operating means 21 and the bucket control valve 19 is 21e is shut off. Thus, the bucket 8c is held at the swing stroke end. Further, even if the bucket operation lever 21a is operated, the bucket cylinder 8f does not operate. Then, the bucket 8c is locked at the end of the swing stroke.

When the crane operation switch 30 is off at step S-1 and when the pressure switch 61a of the bucket detecting means 61 is off at step S-3, at step S-5, the pilot oil shutoff valve 62 is turned off.
Is not energized and is kept off. In this state, the bucket 8c is not located at the end of the swing stroke. The operation of the bucket cylinder 8f is not restricted. When the crane operation switch 30 in the ON state is turned off, the power supply to the pilot oil cutoff valve 62 is stopped, so that the operation means 21 can operate the bucket cylinder 8f.

As described above, the present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be variously modified or modified within the scope of the present invention. It is. For example,

(1) If the control pressure output valve 40b having the electromagnetic proportional pressure reducing valve of the discharge oil amount reducing means 40 does not need to adjust the control pressure, the pressure oil from the constant pressure source 45 as shown in FIG. May be used as the control pressure intermittent valve 46 which switches and outputs the control pressure. The control pressure interrupting valve 46 has an electromagnetic valve, and is energized and energized when the crane operation switch 30 is turned on, and outputs pressure oil from the constant pressure source 45 to the shuttle valve 40a as control pressure.

(2) The pilot oil control valve 50b having the electromagnetic proportional pressure reducing valve of the actuator
If it is not necessary to change and adjust the pressure, an electromagnetic throttle valve 55 having a fixed throttle 55a as shown in FIG. 5 can be used. The electromagnetic throttle valve 55 is connected to the crane operation switch 30.
Is turned on, the pilot pressure oil in the pilot oil passage 20e that has switched the boom control valve 18 is gradually released to the drain 23 via the fixed throttle 55a.

(3) The bucket detecting means 61 has a pressure switch 61a provided in the oil passage 19d to the bucket cylinder 8f. The bucket detecting means 61 detects the swing position of the bucket 8c. Therefore, appropriate means such as a limit switch provided at the telescopic end of the bucket cylinder 8f and a limit switch provided at the swinging end of the bucket 8c can be used.

(4) The bucket lock means 60 is provided so as to be positioned at the end of the swing stroke in which the bucket cylinder 8f is extended to wind the bucket 8c.
The pressure switch 61a of the bucket detecting means 61 may be provided in the rod-side oil passage 19e of the bucket cylinder 8f so that the bucket cylinder 8f is contracted to position the bucket 8c at the swing stroke end where the bucket 8c is projected.

[0051]

According to the hydraulic excavator having the crane operation mode configured according to the present invention, (1) when performing the crane operation, the hydraulic excavator can be operated without finely operating the operation lever of the hydraulic actuator. The hydraulic fluid is slowed down and the crane operation is facilitated because the oil discharge of the pump is limited and reduced. (2) When performing a crane operation, if the working arm enters the limit working range while operating the hydraulic actuator, the hydraulic actuator is automatically decelerated and stopped. Shaking of the suspended load, unstable posture of the hydraulic shovel, and the like are prevented, and crane work is facilitated. (3) When performing a crane operation, when the bucket is moved to the end of the swing stroke, the bucket is stopped and held at that position, and the bucket cylinder does not operate even when the bucket operation lever is operated. It is not necessary to always fix the position of the bucket and correct the position of the bucket, and the crane operation becomes easy. (3) Turning on the crane operation switch makes the crane operation easier, and turning off the crane operation switch makes it possible to use the functions of the conventional hydraulic excavator as it is to perform operations such as excavation and loading. Can be operated efficiently for general purpose.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic excavator having a crane operation mode configured according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a discharge oil amount Q and a pressure signal P defining the discharge oil amount of the variable displacement hydraulic pump of the hydraulic shovel configured according to the present invention.

FIG. 3 is a flowchart showing an operation procedure of a bucket locking means of the hydraulic shovel configured according to the present invention.

FIG. 4 is a hydraulic circuit diagram showing a control pressure interrupting valve as another embodiment of the control pressure output valve of the discharge oil amount reducing means.

FIG. 5 is a hydraulic circuit diagram showing an electromagnetic throttle valve as another embodiment of the pilot oil control valve of the actuator deceleration stop means.

FIG. 6 is a side view of a hydraulic excavator performing a crane operation.

[Explanation of symbols]

 2: hydraulic excavator 8: working arm 8a: boom 8b: arm 8c: bucket 8d: boom cylinder (hydraulic actuator) 8f: bucket cylinder (hydraulic actuator) 10: hook 12: hanging load 14: variable displacement hydraulic pump 16: hydraulic Actuator 17: Direction control valve 17a: Center bypass oil passage 18: Boom control valve 19: Bucket control valve 26: Signal oil passage 30: Crane work switch 40: Discharge oil amount reducing means 40a: Shuttle valve 40b: Control pressure output valve 46 : Control pressure cutoff valve 50: Actuator deceleration means 50 a: Pilot oil control valve 51: Work range detection means 55: Electromagnetic throttle valve 60: Bucket lock means 61: Bucket detection means 61 a: Pressure switch 62: Pilot oil cutoff valve 62 a: Electromagnetic Switching valve

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Manabu Tamura 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Sanishi Heavy Industries, Ltd.

Claims (9)

[Claims] 1. A hydraulic arm for performing a crane operation by operating a work arm swingably provided on an upper revolving structure by selectively supplying discharge oil of a variable displacement hydraulic pump to a hydraulic actuator by a direction control valve. In the shovel, the hydraulic shovel includes a crane operation switch, and discharge oil amount reducing means for reducing a maximum discharge oil amount of the variable displacement hydraulic pump when the crane operation switch is turned on. Excavator with crane working mode. 2. A hydraulic arm for performing a crane operation by operating a work arm swingably provided on an upper swing body by selectively supplying discharge oil of a variable displacement hydraulic pump to a hydraulic actuator by a direction control valve. In the shovel, the hydraulic excavator includes a crane work switch and a hydraulic actuator that moves the work arm toward the limit work range when the work arm enters a predetermined limit work range when the crane work switch is on. An excavator having a crane operation mode, comprising: an actuator deceleration stop means for stopping while decelerating. 3. A hydraulic arm for performing a crane operation by operating a work arm swingably provided on an upper revolving structure by selectively supplying discharge oil of a variable displacement hydraulic pump to a hydraulic actuator by a direction control valve. In the shovel, the hydraulic shovel includes a crane operation switch, and a bucket lock for fixing a bucket, which is swingably oscillatingly provided by a bucket cylinder at a tip end of the operation arm when the crane operation switch is on, to a swing stroke end. And a hydraulic excavator having a crane working mode. 4. A hydraulic arm for performing a crane operation by operating a work arm swingably provided on the upper swing body by selectively supplying discharge oil of a variable displacement hydraulic pump to a hydraulic actuator by a directional control valve. In the shovel, the hydraulic shovel includes a crane operation switch, discharge oil amount reducing means for reducing a maximum discharge oil amount of the variable displacement hydraulic pump when the crane operation switch is turned on, and the working arm has a predetermined limit operation. An actuator deceleration stop means for stopping the hydraulic actuator moving the work arm in the direction of the limit work range while decelerating when entering the range, and a swing cylinder provided at a tip end of the work arm so as to be swingable by a bucket cylinder. And a bucket lock means for fixing the bucket to the end of the swing stroke. Hydraulic excavator. 5. The discharge oil amount of the variable displacement hydraulic pump is
Negative control, that is, the circuit pressure of the center bypass oil passage of the directional control valve is guided to the variable displacement hydraulic pump as a signal pressure via a signal oil passage, and is regulated on the high pressure side of the signal pressure according to the signal pressure. A minimum discharge oil amount to be controlled and a maximum discharge oil amount defined on the low pressure side of the signal pressure. The discharge oil amount reduction means includes: a shuttle valve provided in the signal oil passage; A control pressure output valve for outputting a pressure, wherein the shuttle valve compares the circuit pressure with the control pressure, and a higher pressure is transmitted to the variable displacement hydraulic pump as the signal pressure through the signal oil passage. Claim 1 or 4
Hydraulic excavator with crane working mode as described. 6. The hydraulic shovel according to claim 5, wherein the control pressure output valve includes an electromagnetic proportional pressure reducing valve. 7. The crane operation mode according to claim 2, wherein said directional control valve is switched by pilot oil, and said actuator deceleration stop means includes a pilot oil control valve for controlling said pilot oil. Hydraulic excavator equipped. 8. The hydraulic shovel according to claim 7, wherein the pilot oil control valve includes an electromagnetic proportional pressure reducing valve. 9. The bucket cylinder is operated by a directional control valve switched by pilot oil, the bucket locking means is a bucket detecting means for detecting a swinging position of the bucket, and the bucket detecting means is a means for detecting the bucket position. 5. The crane operation according to claim 3, further comprising a pilot oil shutoff valve that shuts off the pilot oil when it is detected that the directional control valve is located at the end of the swing stroke and holds the directional control valve at the neutral position. Hydraulic excavator with mode.