JP2007126962A - Working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working machine capable of selecting excavation work or crane work by a working attachment equipped with a telescopic arm. <P>SOLUTION: The working machine constituted to be switched to a normal work mode of carrying out excavation and to a crane work mode of carrying out hanging work by a hanging hook, comprises an arm lock pin 18 locking the extension of the arm 7 in the crane work mode; a proximity sensor for detecting that the arm 7 is locked by the arm lock pin 18; a display; and a controller for displaying actual load, rated load, or the like on the display when the lock of the arm 7 is detected by the proximity sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a work machine capable of appropriately selecting excavation work and crane work, and more particularly to a work machine in which a work attachment is provided with a telescopic arm.

  Conventionally, a work attachment for a hydraulic excavator is generally constituted by a boom, an arm, and a bucket, but one that can extend and contract the arm is known.

  FIG. 6 shows a work attachment 50 having the telescopic arm.

  In the figure, the telescopic arm 51 is composed of a lower arm 53 connected to the tip of the boom 52 and an upper arm 54 that slides on the lower arm 53, and the tip of the upper arm 54. A bucket 55 is connected to the bucket.

  By using the work attachment 50 provided with the telescopic arm 51, the work radius can be expanded in the horizontal direction in excavation work, or deeper than the conventional arm.

  On the other hand, as shown in FIG. 7, there is also known a hydraulic excavator in which a work hook 60 is provided with a suspension hook 61 so that crane work can be performed.

  The work attachment 60 in this case is mainly composed of a boom 62, an arm 63 that does not have a telescopic function, and a bucket 64.

  The suspension hook 61 is stored in a bucket link 66 interposed between the bucket 64 and the bucket cylinder 65 during excavation work, and the suspension hook 61 is fixed to the bucket link 66 when performing crane work. The connecting pin is removed and the hanging hook 61 is suspended. At this time, the bucket 64 is drawn to the maximum and retracted to a position where it does not interfere with the hanging hook 61.

  In this state, the hydraulic excavator can be operated as a crane by raising the arm 63, raising the boom 62, or performing a combined operation of both.

  However, the conventional hydraulic excavator described above has a disadvantage that the crane work cannot be performed with the work attachment provided with the telescopic arm.

  In addition, although the crane attachment and the excavation work can be selected as appropriate in the work attachment with the hanging hook, the work radius can be expanded or deepened like the work attachment with the telescopic arm in the excavation work. There is an inconvenience that it cannot

  In this way, there is no work attachment that has both an extendable arm and a suspension hook. The work attachment that allows the arm to expand and contract arbitrarily will change the rated load when carrying out crane work, ensuring the stability of the aircraft. This is because there is a risk that it will not be possible.

  The present invention has been made in consideration of the problems in the conventional hydraulic excavator as described above, and provides a work machine capable of selecting excavation work and crane work with a work attachment having an extendable arm. Is.

  The present invention includes a base machine, a work attachment having a base attached to the base machine, a telescopic arm attached to the tip of the boom, and a work device attached to the tip of the arm; A work machine comprising a suspension hook provided on the work attachment and capable of switching between a normal work mode in which a normal work such as excavation is performed by the work device and a crane work mode in which the work is suspended by the suspension hook. The arm lock means for locking the expansion / contraction operation of the arm in the most contracted state is provided, and the arm expansion / contraction operation is locked by the arm lock means, thereby switching to the crane work mode. It is a work machine.

  According to the present invention, when the crane work is performed, the expansion and contraction of the arm that is in the most contracted state can be locked. Therefore, even if the operator erroneously operates the arm expansion and contraction lever, the arm does not expand and contract. It is possible to prevent the suspension capacity from changing.

  In this invention, it can be set as the structure switched to the said normal operation mode by releasing the lock | rock of the expansion-contraction operation | movement of the said arm by the said arm lock means.

  In the present invention, the arm is telescopically configured by a fixed arm and a movable arm slidably inserted into the fixed arm, and the arm lock means is a lock pin provided on the fixed arm and the movable arm. It can be constituted by a hole and an arm lock pin inserted across the lock pin holes of both the fixed and movable arms.

  In the present invention, the hanging hook is attached to the work attachment so that it can be stored and extended, and the hanging hook can be stored and fixed by an arm lock pin.

  In this way, when excavating work, the suspension hook is stored in the bucket and the suspension hook is fixed, and if the pin that is removed during crane work is used as an arm lock pin, switching from excavation work to crane work is ensured. The operation mistakes can be resolved. In addition, loss of the pin can be prevented.

  In the present invention, the work machine includes a lock detecting means for detecting that the arm expansion / contraction operation is locked, and an actual load during the crane operation and an allowable suspension when the lock of the arm is detected by the lock detecting means. And a control means for operating an indicator that displays a working state such as a load.

  According to the present invention, when the arm is locked, the actual load and the allowable suspension load necessary for the crane work are displayed on the display, so that it is possible to confirm whether the switching to the crane work has been performed reliably. it can.

  In the present invention, the work machine has a lock detection means for detecting that the extension / contraction operation of the arm is locked, and an actual load at the time of crane work when the lock detection means detects the lock of the arm, Control means for operating an indicator that displays work conditions such as allowable lifting load, etc., and the arm lock pin is inserted across the lock pin holes of both fixed and movable arms as the lock detection means It is possible to use a sensor for detecting This sensor is preferably composed of a non-contact type sensor such as a proximity switch, but may be composed of a contact type sensor such as a limit switch.

  In the present invention, the arm lock means may be configured to lock a drive circuit of an arm cylinder that extends and contracts the arm.

  In this configuration, the working machine is compared with the actual load by the arm length detecting means for detecting the amount of expansion and contraction of the arm, and the allowable suspension load that changes according to the arm length detected by the arm length detecting means, An overload prevention means for locking the drive circuit of the arm cylinder when the actual load exceeds the allowable suspension load can be provided.

  According to this configuration, since the arm is locked when the allowable suspension load value exceeds the actual load value, the crane can be operated by arbitrarily extending and retracting the arm within a range where the suspension load value does not exceed the actual load value. it can. Thereby, at the time of crane work, it becomes possible to operate the telescopic arm to perform horizontal pull-in or to perform horizontal insertion, and the crane workability can be greatly improved.

  Furthermore, the present invention provides a work attachment having a base machine, a boom having a base end attached to the base machine, a telescopic arm attached to the tip of the boom, and a working device attached to the tip of the arm. And a suspension hook provided on the work attachment, and is configured to be switchable between a normal work mode in which normal work such as excavation is performed by the work device and a crane work mode in which the work is hung by the suspension hook. In a work machine, the arm includes a fixed arm, a movable arm that is slidably inserted into the fixed arm, and an arm cylinder that expands and contracts the movable arm with respect to the fixed arm, and is configured to telescopically expand and contract. The fixed arm and the movable arm can be connected so as not to be relatively movable. Arm lock means, second arm lock means capable of locking the drive circuit of the arm cylinder, lock detection means for detecting that the extension / contraction operation of the arm by the first arm lock means is locked, and And a control unit that locks a drive circuit of the arm cylinder by the second arm lock unit when the lock of the arm expansion / contraction operation is detected by the lock detection unit.

  According to the present invention, since the extension / contraction of the arm can be locked when the crane work is performed, even if the operator mistakenly operates the lever of the arm extension / contraction, the arm does not extend / contract, and the suspension capacity changes in the crane work. Can be prevented.

  In the present invention, it further comprises a work mode changeover switch capable of outputting a signal indicating that the normal work mode or the crane work mode is selected to the control means, and the control means is configured to extend and retract the arm by the lock detection means. While the lock is detected, the arm cylinder drive circuit can be locked regardless of the output signal from the work mode changeover switch.

  In the present invention, when the lock of the extension / contraction operation of the arm is detected by the lock detection means and a signal indicating that the crane work mode is selected from the work mode changeover switch, the control means is operated. It can be set as the structure further provided with the alerting | reporting means.

  In the present invention, a work mode changeover switch capable of outputting a signal indicating that the normal work mode or the crane work mode is selected to the control means, and a work state such as an actual load and an allowable suspension load during crane work is displayed. The control means, when the lock detecting means detects the lock of the arm extension and contraction, and receives a signal indicating that the crane work mode is selected from the work mode changeover switch. Moreover, it can be set as the structure which operates the said indicator.

  In the present invention, the first arm lock means includes a lock pin hole provided in the fixed arm and the movable arm, and an arm lock pin inserted across the lock pin holes of the fixed and movable arms. A plurality of lock pin holes of the movable arm are provided at intervals in the arm length direction, and the arm lock spans one lock pin hole selected from the lock pin holes and the lock pin hole of the fixed arm. If the pins are inserted, the crane work can be performed even when the movable arm is extended.

  In the present invention, the work machine has a boom cylinder for raising and lowering the boom with respect to the base machine, a raising and lowering arm cylinder for raising and lowering the arm with respect to the boom cylinder, and at least one of the boom cylinder and the raising and lowering arm cylinder. The operation amount of at least one of the flow rate adjustment valve that adjusts the return oil amount from the load holding side oil chamber in one cylinder and the operation body that operates the boom cylinder and arm cylinder when switched to the crane work mode. Accordingly, load holding means for controlling the flow rate adjusting valve can be provided.

  As is apparent from the above description, according to the present invention according to claims 1 and 9, it is possible to switch between a normal work mode in which a normal work such as excavation is performed and a crane work mode in which a hung work is performed with a hanging hook. The work machine configured includes an arm lock unit (first arm lock unit) that locks the expansion and contraction operation of the arm in the most contracted state, and the arm expansion and contraction operation is locked by the arm lock unit. Since it is configured to be switched to the crane work mode, the arm does not expand and contract even if the operator mistakenly operates the lever for arm expansion and contraction, and the suspension capacity can be prevented from changing during crane work. Thereby, even if it is a working machine provided with a telescopic arm in a work attachment, it becomes possible to perform a crane work safely.

  According to the third aspect of the present invention, in the configuration in which the arm telescopically expands and contracts by the fixed arm and the movable arm that is slidably inserted into the fixed arm, the arm locking means is divided into the fixed arm and the movable arm. Since the lock pin holes are provided and the arm lock pins are inserted into the lock pin holes, the arm can be locked without significantly changing the design of the existing telescopic arm.

  According to the fourth aspect of the present invention, the suspension hook is attached to the work attachment so that the suspension hook can be stored and extended, and the suspension hook can be stored and fixed by the arm lock pin. Can be reliably switched and operation errors can be eliminated. In addition, loss of the pin can be prevented.

  According to the fifth aspect of the present invention, the lock detecting means for detecting that the arm expansion / contraction operation is locked to the work machine, and when the lock of the arm is detected by the lock detecting means, the crane is operated. Control means that activates the indicator that displays the work status such as actual load and allowable suspension load, so that the actual load and allowable suspension load necessary for crane work are displayed on the indicator when the arm is locked. Thus, it can be easily confirmed whether or not the switching to the crane work has been performed reliably.

  According to the present invention of claim 6, since the sensor for detecting that the arm lock pin is inserted across the lock pin holes of both the fixed and movable arms is used as the lock detection means, the lock pin is inserted. The arm lock can be recognized with a single operation.

  According to the seventh aspect of the present invention, since the arm lock means is configured to lock the drive circuit of the arm cylinder that extends and retracts the movable arm, the arm can be locked without newly adding a lock mechanism. .

  According to the eighth aspect of the present invention, the work machine has arm length detection means for detecting the amount of expansion / contraction of the arm, and allowable suspension load that changes according to the arm length detected by the arm length detection means. Is provided with an overload prevention means that locks the arm cylinder drive circuit when the actual load exceeds the allowable load, so that the arm is locked when the allowable load exceeds the actual load. The Therefore, the crane can be operated by arbitrarily extending and retracting the arm within a range where the suspended load value does not exceed the actual load value. Thereby, at the time of crane work, it becomes possible to operate the telescopic arm to perform horizontal pull-in or to perform horizontal insertion, and the crane workability can be greatly improved.

  According to the present invention of claim 13, a plurality of lock pin holes of the movable arm are provided at intervals in the arm length direction, and one lock pin hole selected from these and a lock pin hole of the fixed arm are provided. Since the arm lock pin is inserted so as to straddle, the crane work can be performed even when the movable arm is extended.

  According to the fourteenth aspect of the present invention, the work machine is provided with a flow rate adjusting valve for adjusting a return oil amount from the load holding side oil chamber in at least one of the boom cylinder and the arm cylinder in the work attachment, and a crane. A load holding means for controlling the flow rate adjusting valve according to the amount of operation of at least one of the operating body that operates the boom cylinder and the arm cylinder when the operation mode is switched to the normal operation mode such as excavation. Can be reliably switched to the crane work mode.

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

  FIG. 1 shows the overall configuration of a hydraulic excavator as a work machine according to the present invention.

  In FIG. 1, a hydraulic excavator 1 includes a work attachment 4 that can be raised and lowered at a front portion of a base machine in which an upper swing body 3 is rotatably mounted on a lower traveling body 2.

  A driver's cab 5 is disposed on the left side of the front part of the upper swing body 3, and a driver's seat on which an operator sits, an operation lever, a display, and the like are provided.

  The work attachment 4 includes a boom 6 that is raised and lowered by an expansion / contraction operation of the boom cylinder 6a, an expansion / contraction arm 7 that is connected to the tip of the boom 6 and that is pulled or pushed by the expansion / contraction operation of the arm cylinder 7a, and the expansion / contraction arm. 7 is connected to the tip end of the bucket 7 and rotated by the expansion and contraction operation of the bucket cylinder 8a. The bucket 8 is stored on the back side of the bucket 8 during excavation work, and is pulled out and suspended in the direction of arrow A during crane work. The suspension hook 9 is mainly configured.

  FIG. 2 is an enlarged view of the telescopic arm 7.

  The telescopic arm 7 includes a lower arm (fixed arm) 10 having a U-shaped cross section, a cylindrical upper arm (movable arm) 11 fitted to the lower arm 10, and an upper arm 11. The telescopic arm cylinder 12 is accommodated and slides the upper arm 11 using the lower arm 10 as a guide.

  The tube side boss 12a of the telescopic arm cylinder 12 is connected to the side wall of the lower arm 10 via a pin 12b, and the rod side boss 12c is connected to the side wall of the upper arm 11 via a pin 12d. .

  Further, rail portions 13 and 14 (illustrated only on the front side) are provided at the upper corners of the upper arm 11, and a slider 15 that slides while supporting the rail portions 13 and 14 serves as the lower arm 10. Is provided at the opening edge of the. Therefore, when the rod 12e of the telescopic arm cylinder 12 is extended, the upper arm 11 is drawn out in the arrow B direction by being guided by the slider 15. A rib 16 is provided on the bottom surface of the lower arm 10, and a boss 16 a for connecting to the tip of the boom 6 is provided on the rib 16.

  In addition, a lock pin hole 17 for inserting an arm lock pin, which will be described later, is provided on each side wall of the front end portion of the lower arm 10. The arm lock pin and the lock pin hole 17 function as arm lock means (first arm lock means).

  FIG. 3 is a cross-sectional view taken along the line CC of FIG. 2 and shows a lock structure for locking the lower arm 10 and the upper arm 11.

  The lower arm 10 is formed in a bowl shape by a bottom plate portion 10a and both side wall portions 10b and 10c, and bosses 19 and 20 for inserting arm lock pins 18 are attached to the positions of the lock pin holes 17, respectively. ing.

  The bosses 19 and 20 basically have the same configuration. The boss 19 will be described as a representative. Bolt holes 19b through which a plurality of bolts 21 pass are formed in the flange portion 19a formed in the body portion thereof, while these bolt holes 19b are formed in the side wall portion 10b. A female screw portion 10d is formed corresponding to the above. The flange portion 19a is fixed to the side wall portion 10b by tightening the bolt 21 through the bolt hole 19b to the female screw portion 10d.

  In addition, 20a is a flange part formed in the boss | hub 20, 22 is a volt | bolt for fixing the flange part 20a to the side wall part 10c.

  On the other hand, the upper arm 11 housed in the lower arm 10 is formed in a rectangular tube shape by a bottom plate portion 11a, both side wall portions 11b and 11c, and a top plate portion 11d.

  A cylindrical portion 11e is provided in the X-axis direction at the front end portion of the upper arm 11, and this cylindrical portion 11e is described above when the upper arm 11 is stored in the lower arm 10 and is in the most contracted state. The arm lock pin 18 can be passed through facing the lock pin holes of the bosses 19 and 20.

  Therefore, when the arm lock pin 18 is inserted in the order of the boss 19 → the cylindrical portion 11e → the boss 20, the upper arm 11 is locked to the lower arm 10 in the most contracted state.

  Further, a proximity switch (lock detection means) 23 is disposed in the vicinity of the tip 18a of the inserted arm lock pin 18 with a predetermined gap S therebetween. The proximity switch 23 functions as a sensor, and outputs a lock completion signal when the arm lock pin 18 is inserted and the tip 18a enters the detection range. Reference numeral 24 denotes a protective cover for protecting the proximity switch 23. Reference numerals 15 a, 15 b and 15 c denote slider pads disposed in the slider 15.

  FIG. 4 shows the hydraulic circuit of this embodiment. In order to simplify the description, the description will focus on a circuit related to switching between excavation work and crane work.

  First, a circuit for raising and lowering the arm 7 as a crane operation will be described.

  The pressure oil discharged from the first hydraulic pump 30 is supplied to the arm cylinder 7 a via the direction control valve 31.

  Between the rod side oil chamber 7a1 of the arm cylinder 7a and the direction control valve 31, a counter balance valve 32 including a check valve 32a and a holding valve (flow rate adjusting valve) 32b is provided.

  Further, a relief valve 33 is provided between the rod side oil chamber 7a1 and the counter balance valve 32 so that when the pressure oil pressure exceeds a set pressure, excess pressure oil is released to the tank 34.

  The direction control valve 31 is switched by a switching operation of the operation lever (operation body) 34. When the operation lever 34 is tilted to the “a” side, the direction control valve 31 is switched to the “d” position, and the arm cylinder. 7a shrinks. As a result, a lifting operation (pushing the arm in excavation work) is performed.

  On the contrary, when the operation lever 34 is tilted to the “b” side, the direction control valve 31 is switched to the “e” position, and the arm cylinder 7a is extended. Thereby, the suspending (arm pulling in excavation work) operation is performed.

  A work mode switching valve 35 is interposed between the holding valve 32 and the operation lever 34. The work mode switching valve 35 is normally in the switching position f and applies the control pressure sent from the pilot pump 36 to the holding valve 32b to switch to the communication position h, but when the switching signal S1 is given from the controller 37. Then, the position is switched to the switching position g, and the holding valve 32b is switched from the communication position h to the cutoff position i in accordance with the switching signal S1. The controller 37 and the work mode switching valve 35 function as load holding means.

  A detection signal S2 output from the proximity switch 23 is constantly input to the controller 37. Further, a work mode signal S3 is inputted from a work mode changeover switch 38 in which the operator selects either the excavation work mode (normal work mode) or the crane work mode. Further, a display device 39 comprising a liquid crystal display and an alarm buzzer 40 are connected to the controller 37.

  FIG. 5 shows the display 39. The display 39 includes a display unit 39a for displaying an actual load value calculated by the controller 37, an allowable suspension load value, a working radius, and the like, an indicator 39b that is lit when the actual load exceeds 90% of the allowable suspension load, Similarly, an indicator 39c that is turned on when exceeding 100%, an actual load switch 39d that displays an actual load, an allowable suspension load switch 39e that displays an allowable suspension load, and a work radius switch 39f that displays a work radius are provided. .

  The work mode changeover switch 38 is arranged in a control box behind the driver's seat, the alarm buzzer 40 is incorporated in the indicator 39, and this indicator 39 is arranged in front of the driver's seat in the cab 5. Yes.

  Next, the control circuit of the telescopic arm cylinder 12 will be described.

  The pressure oil discharged from the second hydraulic pump 41 is supplied to the telescopic arm cylinder 12 via the direction control valve 42.

  The switching of the direction control valve 42 is performed by a switching operation of the operation pedal 43. When the operation pedal 43 is tilted to the “j” side, the direction control valve 42 is switched from the neutral position “l” to the “m” position. Pressure oil is supplied to the rod side oil chamber 12a and the telescopic arm cylinder 12 is reduced. Thereby, the upper arm 11 is stored in the lower arm 10.

  On the contrary, when the operation pedal 43 is tilted to the “k” side, the direction control valve 42 is switched from the neutral position “l” to the “n” position, and pressure oil is supplied to the head side oil chamber 12b to extend the telescopic arm. The cylinder 12 extends. Thereby, the upper arm 11 is pulled out from the lower arm 10.

  Further, switching valves 44 and 45 are interposed between the direction control valve 42 and the operation pedal 43, respectively. These switching valves 44 and 45 are switching signals output from a controller 37 as control means. In response to S4, the communication position “o” is switched to the operation lock position “p”. When the operation lock position “p” is switched, the operation pedal 43 cannot be operated.

  Next, control of the hydraulic circuit having the above configuration will be described.

  It is assumed that the upper arm 11 is in the most contracted state.

  When carrying out the crane work, the hook fixing pin is pulled out and the hanging hook 9 folded on the back side of the bucket 8 is pulled out and suspended.

  This hook fixing pin is used as the arm lock pin 18 shown in FIG. 3, and is inserted in the order of the boss 19 → the cylindrical portion 11e → the boss 20. Thereby, the upper arm 11 and the lower arm 10 are locked.

  When the arm lock pin 18 is inserted, a detection signal S 2 is output from the proximity switch 23 and is given to the controller 37.

  Here, when the operator switches the work mode changeover switch 38 to “crane” as the crane work mode, a work mode signal S 3 is given to the controller 37.

  The controller 37 monitors the output states of the work mode signal S3 and the detection signal S2. If the detection signal S2 is not obtained, the upper arm 11 and the lower arm 10 are not fixed by the arm lock pin 18. Therefore, the alarm buzzer 40 is sounded to prompt the operator to confirm. Further, since the arm lock pin 18 also serves as a hook fixing pin for storing and fixing the suspension hook 9, the operator does not hang down the suspension hook 9 due to the alarm buzzer 40 and is ready for crane work. You can know what is not done.

  When the detection signal S2 is obtained, the controller 37 first outputs a switching signal S4 to the switching valves 44 and 45, respectively, and changes the switching position of each switching valve 44, 45 from the communication position "o" to the operation lock position ". Switch to p ". As a result, the telescopic arm cylinder 12 becomes inoperable regardless of which direction the operation pedal 43 is operated. Therefore, a dangerous operation of extending the upper arm 11 while the load is suspended is prevented.

  When the detection signal S2 and the work mode signal S3 are obtained and the work mode signal S3 indicates a crane, the actual load switch 39d for displaying the actual load and the allowable suspension load switch 39e for displaying the allowable suspension load are effective. Thus, the actual load value and the allowable suspension load value can be displayed on the screen of the display 39. Next, the controller 37 switches the work mode switching valve 35 from the “f” position to the “g” position.

  When the operation lever 34 is operated in the “a” direction as “lifting” in this state, the directional control valve 31 is switched from the neutral position “c” to “d”, and the rod side oil chamber of the arm cylinder 7a is passed through the check valve 32a. Pressure oil is supplied to 7a1.

  Therefore, whether or not the work mode switching valve 35 is switched is not affected in the lifting operation.

  On the other hand, when the operation lever 34 is operated in the “b” direction as “hanging”, the direction control valve 31 is switched from the neutral position “c” to “e”, and pressure oil is supplied to the head side oil chamber 7a2 of the arm cylinder 7a. Is supplied.

  The pressure oil discharged from the rod side oil chamber (load holding side oil chamber) 7a1 by the expansion of the head side oil chamber 7a2 passes through the counter balance valve 32 and returns to the tank, but the holding valve 32b of the counter balance valve 32 is used. A pilot pressure Pb corresponding to an operation amount for operating the operation lever 34 in the hanging direction is applied to the control port via the work mode switching valve 35.

  Thus, the flow rate of the pressure oil returning from the rod side oil chamber 7a1 to the tank is determined by the opening degree of the holding valve 32b. Therefore, when the load is suspended, it is possible to suppress an increase in the descending speed of the arm 7 due to the suspended load, and as a result, the crane work can be safely performed using the work attachment of the hydraulic excavator. Become.

  Further, when the work mode changeover switch 38 is switched from “crane” to “excavator” as excavation work, excavation work can be selected. At this time, if the arm lock pin 18 remains inserted, the proximity switch Since the detection signal S2 is continuously output from 23, the telescopic arm cylinder 12 is still inoperable.

  In this case, the controller 37 sounds the alarm buzzer 40 and notifies the operator that the arm lock pin 18 has been forgotten to be removed. Note that it is preferable to change the buzzer sound between forgetting to insert the arm lock pin 18 in the crane work and forgetting to remove the arm lock pin 18 in the current excavation work.

  In the above-described embodiment, the case where the crane operation is performed by raising and lowering the arm 7 has been described. However, the crane operation can also be performed by raising and lowering the boom 6. In this case, the counter balance valve 32 having the above-described configuration may be provided in the supply / discharge path connecting the head side oil chamber of the boom cylinder 6a and the tank.

  Further, when the crane operation is performed by performing the combined operation of the boom cylinder 6a and the arm cylinder 7a, the counter balance valve 32 can be provided in each of the cylinders 6a and 7a, and the controller 37 can control the combined operation.

  Moreover, although the lock | rock detection means of this invention was comprised with the non-contact-type proximity switch in the said embodiment, it can comprise not only this but a contact-type sensor, such as a limit switch.

  In the above embodiment, the lock pin hole 17 of the arm lock pin 18 is provided at one position on the front end portion of the lower arm 10 so that the crane work can be performed after the telescopic arm 7 is locked in the most contracted state. Not limited to this, a plurality of cylinder portions (lock pin insertion holes) 11e are provided in the longitudinal direction of the upper arm 11, and the arm lock pin 18 is inserted into any one of the cylinder portions 11e and the lock pin hole 17, thereby 11 can be configured to be locked with an arbitrary length.

  According to this configuration, the upper arm 11 does not necessarily need to be in the most contracted state, and the crane work can be performed after being pulled out and locked to a desired length. Thereby, the crane work can be performed while utilizing the original function of the telescopic arm that enlarges the working radius. However, in this configuration, the suspension capacity decreases as the upper arm 11 is pulled out. Therefore, it is preferable to calculate the allowable suspension load for each lock position where the upper arm 11 is locked and display it on the display 39.

  Further, in the above embodiment, the arm lock means of the present invention is configured to fix the upper arm 11 and the lower arm 10 with the arm lock pin 18, but not limited to this, the hydraulic pump is connected to the telescopic arm cylinder 12. It can also comprise so that the pressure oil of the supply / exhaust path which leads may be locked.

  That is, the telescopic arm 7 is provided with a stroke sensor (arm length detecting means) such as a cord reel type length sensor for detecting the extension amount, and an overload prevention device (overload prevention means) is provided in the cab 5. It is also possible to calculate the allowable suspension load during crane work based on the arm length signal detected by the stroke sensor and display it on the display 39.

  The overload prevention device is connected to the stroke sensor of the telescopic arm cylinder 12 and the pressure sensor of the boom cylinder 6a. The memory stores the allowable suspension load of the telescopic arm 7, and the actual load by the pressure of the boom cylinder. A control unit for calculating the value is provided.

  The memory stores from a minimum allowable suspension load value when the telescopic arm 7 is extended to a maximum allowable suspension load value when the telescopic arm 7 is contracted to the minimum. The allowable suspension load value corresponding to the extension length of the movable arm 11 at 12 is read from the memory and given to the control unit.

  The control unit always compares the allowable suspension load value read from the memory with the actual load value, and outputs a signal when the actual load value exceeds the allowable suspension load value in the comparison result.

  Upon receiving this signal, the overload prevention device sounds the alarm buzzer 40 and locks the telescopic arm cylinder 12.

  The display 39 always displays the allowable suspension load and actual load at the current movable arm extension position, and the load factor that is the ratio. For example, the indicator 39b is lit when the actual load exceeds 90% of the allowable suspension load, and the indicator 39c is lit when it exceeds 100%.

  The display 39 displays the allowable suspension load value in the maximum extended state. By doing so, the operator can extend and extend the telescopic arm 7 horizontally if it is a suspended load having a weight equal to or less than the minimum allowable suspended load value, and the workability of crane work is greatly improved.

  Thus, since the overload prevention device displays the allowable suspension load and the actual load that change due to the expansion and contraction operation of the arm on the display 39, the operator can perform the crane work while grasping the allowable suspension load in the arm maximum extension state. It can be done safely.

  The above-described allowable suspension load may be a rated load or may be a value obtained by adding a predetermined safety factor to the rated load.

It is an external view of the construction machine provided with the expansion-contraction arm which concerns on this invention. It is an enlarged view of the telescopic arm of FIG. It is CC sectional drawing of FIG. It is a hydraulic circuit diagram of the arm cylinder and the telescopic arm cylinder according to the present invention. It is explanatory drawing which shows the structure of the indicator arrange | positioned at a cab. It is explanatory drawing which shows the work attachment provided with the conventional expansion-contraction arm. It is explanatory drawing which shows the work attachment provided with the conventional hanging hook.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic excavator 2 Lower traveling body 3 Upper revolving body 4 Work attachment 5 Operator's cab 6 Boom 7 Telescopic arm 7a Arm cylinder 8 Bucket 9 Hanging hook 10 Lower arm 11 Upper arm 12 Telescopic arm cylinder 13, 14 Rail section 15 Slider 18 Arm Lock pin 23 Proximity switch 37 Controller 38 Work mode switch 39 Display 40 Alarm buzzer

Claims (14)

A work attachment having a base machine, a boom having a base end attached to the base machine, a telescopic arm attached to the tip of the boom, and a work device attached to the tip of the arm, and the work attachment In a working machine comprising a hanging hook provided and configured to be switchable between a normal work mode in which a normal work such as excavation is performed by the working device and a crane work mode in which a hanging work is performed by the hanging hook.
Arm locking means for locking the expansion and contraction motion of the arm in the most contracted state,
A working machine characterized in that the arm locking means is switched to the crane work mode by locking the extension / contraction operation of the arm.   2. The work machine according to claim 1, wherein the arm operation unit is switched to the normal operation mode by releasing the lock of the extension / contraction operation of the arm by the arm lock unit.   The arm is telescopically configured by a fixed arm and a movable arm slidably inserted into the fixed arm, and the arm lock means is a lock pin provided on the fixed arm and the movable arm. The work machine according to claim 1 or 2, comprising a hole and an arm lock pin inserted across the lock pin holes of both the fixed and movable arms.   The said suspension hook is attached so that accommodation and extension with respect to the said work attachment are possible, and it is comprised so that this suspension hook can be stored and fixed with the said arm lock pin. Working machine.   Lock detection means for detecting that the arm's telescopic operation is locked, and when the lock of the arm is detected by the lock detection means, the actual load, allowable suspension load, etc. The work machine according to any one of claims 1 to 4, further comprising control means for operating a display for displaying the work state.   Lock detection means for detecting that the arm's telescopic operation is locked, and when the lock of the arm is detected by the lock detection means, the actual load, allowable suspension load, etc. And a control means for operating a display for displaying the working state of the sensor, and as the lock detection means, a sensor for detecting that the arm lock pin is inserted across the lock pin holes of both fixed and movable arms. The working machine according to claim 3, wherein:   The work machine according to claim 1, wherein the arm lock means is configured to lock a drive circuit of an arm cylinder that extends and contracts the arm.   The work machine compares the arm length detection means for detecting the amount of expansion and contraction of the arm and the allowable suspension load that changes according to the arm length detected by the arm length detection means with the actual load. The work machine according to claim 7, further comprising overload prevention means for locking the drive circuit of the arm cylinder when the allowable suspension load exceeds. A work attachment having a base machine, a boom having a base end attached to the base machine, a telescopic arm attached to the tip of the boom, and a work device attached to the tip of the arm, and the work attachment In a working machine comprising a hanging hook provided and configured to be switchable between a normal work mode in which a normal work such as excavation is performed by the working device and a crane work mode in which a hanging work is performed by the hanging hook.
The arm includes a fixed arm, a movable arm that is slidably inserted into the fixed arm, and an arm cylinder that expands and contracts the movable arm with respect to the fixed arm, and is configured to telescopically expand and contract.
First arm locking means capable of connecting the fixed arm and the movable arm so as not to be relatively movable;
Second arm lock means capable of locking the drive circuit of the arm cylinder;
Lock detecting means for detecting that the arm extending and retracting operation by the first arm locking means is locked;
A work machine comprising: control means for locking the drive circuit of the arm cylinder by the second arm lock means when the lock detecting means detects the lock of the extension / contraction operation of the arm.   The control means further includes a work mode changeover switch capable of outputting a signal indicating that the normal work mode or the crane work mode is selected, and the control means detects the lock of the arm extension / contraction operation by the lock detection means. 10. The work machine according to claim 9, wherein the arm cylinder drive circuit is kept locked regardless of the presence or absence of an output signal from the work mode changeover switch.   When the lock detecting means detects the lock of the extension / contraction motion of the arm and receives a signal indicating that the crane work mode is selected from the work mode changeover switch, a notification means that is operated by the control means is provided. The work machine according to claim 10, further comprising:   A work mode change-over switch capable of outputting a signal indicating that the normal work mode or the crane work mode is selected to the control means, and an indicator for displaying a work state such as an actual load and an allowable suspension load during crane work; The control means further comprises the display when the lock detecting means detects that the arm has been locked and the crane operation mode is selected from the work mode change-over switch. The work machine according to any one of claims 9 to 11, wherein the working machine is operated.   The first arm locking means includes a lock pin hole provided in the fixed arm and the movable arm, and an arm lock pin inserted across the lock pin holes of the fixed and movable arms, and the movable arm A plurality of lock pin holes are provided at intervals in the arm length direction, and the arm lock pin is inserted across one lock pin hole selected from these and the lock pin hole of the fixed arm. The work machine according to any one of claims 9 to 12, wherein the work machine is configured as described above.   The working machine includes a boom cylinder for raising and lowering the boom with respect to the base machine, a raising and lowering arm cylinder for raising and lowering the arm with respect to the boom cylinder, and at least one of the boom cylinder and the raising and lowering arm cylinder. Depending on the amount of operation of at least one of the flow rate adjustment valve that adjusts the amount of return oil from the load holding side oil chamber and the operating body that operates the boom cylinder and the hoisting arm cylinder when switched to the crane work mode The work machine according to any one of claims 1 to 13, further comprising load holding means for controlling the flow rate adjusting valve.

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