Construction machinery

Abstract

The present invention provides a construction machine that facilitates the combined operation of lowering the boom and driving the hydraulic breaker during the crushing of an object. [Solution] The hydraulic excavator includes a control valve 26 that controls the flow of pressurized oil from the hydraulic pump 21 to the boom cylinder 11, electromagnetic proportional valves 33A and 33B that generate pilot pressure to operate the control valve 26, a work operating device 18A that can lower and raise the boom 8, and a controller 36 that, when the boom 8 is lowered, acquires a control command value for lowering the boom and outputs it to the electromagnetic proportional valve 33A, and when the boom 8 is raised, acquires a control command value for raising the boom and outputs it to the electromagnetic proportional valve 33B. When a combined operation of lowering the boom 8 and driving the hydraulic breaker 10 is performed, the controller 36 limits the control command value for lowering the boom and outputs it to the electromagnetic proportional valve 33A.

Description

Technical Field

[0001] The present invention relates to a construction machine including a working device having a boom, an arm, and a hydraulic breaker.

Background Art

[0002] Patent Document 1 discloses a hydraulic excavator which is one of construction machines. This hydraulic excavator includes a travelable traveling body, a revolving body rotatably provided above the traveling body, and a working device connected to the revolving body. The working device includes a boom rotatably connected to the revolving body, an arm rotatably connected to the boom, and a hydraulic breaker as an attachment rotatably connected to the arm.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described hydraulic excavator, when crushing an object with the hydraulic breaker, while lowering the boom and pressing the chisel of the hydraulic breaker against the object, the hydraulic breaker is driven. During such a crushing operation, at the moment when the object cracks, the boom may suddenly drop, and the chisel of the hydraulic breaker may hit the ground below the object. Therefore, when performing a combined operation involving the boom lowering operation and the hydraulic breaker driving operation, it has been necessary to carefully manually adjust the boom lowering speed.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a construction machine capable of facilitating a combined operation involving a boom lowering operation and a hydraulic breaker driving operation in an operation of crushing an object.

Means for Solving the Problems

[0006] To achieve the above objective, the present invention provides a work device comprising a vehicle body, a boom rotatably connected to the vehicle body, an arm rotatably connected to the boom, and a hydraulic breaker rotatably connected to the arm, a boom cylinder for rotating the boom relative to the vehicle body, a hydraulic pump, a control valve for controlling the flow of pressurized oil from the hydraulic pump to the boom cylinder, a first and second electromagnetic proportional valves for generating pilot pressure to operate the control valve, a first operating device capable of lowering and raising the boom, and a second operating device capable of driving the hydraulic breaker. In a construction machine comprising a boom lowering device and a controller which, when the boom lowering operation is performed by the first operating device, acquires a boom lowering control command value corresponding to the boom lowering operation and outputs it to the first electromagnetic proportional valve, and when the boom raising operation is performed by the first operating device, acquires a boom raising control command value corresponding to the boom raising operation and outputs it to the second electromagnetic proportional valve, the controller further limits the boom lowering control command value and outputs it to the first electromagnetic proportional valve when a combined operation of the boom lowering operation and the hydraulic breaker drive operation is performed. [Effects of the Invention]

[0007] According to the present invention, it is possible to facilitate the combined operation of lowering the boom and driving the hydraulic breaker in the operation of crushing an object. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view showing the structure of a hydraulic excavator in one embodiment of the present invention. [Figure 2] This diagram shows the configuration of the drive unit in one embodiment of the present invention. [Figure 3] This is a block diagram showing the functional configuration of the controller in one embodiment of the present invention, along with related equipment. [Figure 4] This is a flowchart illustrating the controller control procedure in AVA. [Figure 5] This figure shows the configuration of a drive device in one modified example of the present invention. [Figure 6] This is a block diagram showing the functional configuration of a controller in one modified example of the present invention, along with related equipment. [Figure 7] This is a flowchart illustrating the control procedure of a controller in a modified example of the present invention. [Modes for carrying out the invention]

[0009] One embodiment of the present invention will be described with reference to the drawings.

[0010] Figure 1 is a side view showing the structure of the hydraulic excavator in this embodiment.

[0011] The hydraulic excavator of this embodiment comprises a mobile vehicle 1 and a slewing body 2 that is rotatably mounted above the mobile vehicle 1, with the mobile vehicle 1 and the slewing body 2 constituting the vehicle body. The slewing body 2 rotates by the rotation of a slewing motor 3 (see Figure 2, described later).

[0012] The vehicle 1 comprises, for example, an H-shaped track frame 4 when viewed from above, a left crawler 5 rotatably positioned on the left side of the track frame 4 (the side closer to the viewer in Figure 1), a left drive motor 6 that rotates the left crawler 5, a right crawler (not shown) rotatably positioned on the right side of the track frame 4 (the side further away from the viewer in Figure 1), and a right drive motor (not shown) that rotates the right crawler.

[0013] A working device 7 is connected to the slewing body 2. The working device 7 comprises a boom 8 rotatably connected to the slewing body 2, an arm 9 rotatably connected to the boom 8, and a hydraulic breaker 10 as an attachment rotatably connected to the arm 9. The boom 8 rotates by the extension and retraction of the boom cylinder 11, the arm 9 rotates by the extension and retraction of the arm cylinder 12, and the hydraulic breaker 10 rotates by the extension and retraction of the attachment cylinder 13. The hydraulic breaker 10 can be replaced with other attachments.

[0014] The rotating body 2 comprises a rotating frame 14 that forms the lower foundation structure, a driver's cab 15 located on the front side of the rotating frame 14 (left side in Figure 1) where the driver sits, and a machine room 16 located on the rear side of the rotating frame 14 (right side in Figure 1) which houses equipment (specifically, the engine, pump, and control valve unit, etc., which will be described later).

[0015] Inside the driver's cab 15, there is a driver's seat (not shown) where the driver sits. In front of the driver's seat, there is a monitor (not shown) that can display operating information of the hydraulic excavator and allow for setting attachments.

[0016] In front of the driver's seat, there is a driving control device (not shown) that the driver operates with their hands or feet in the forward and backward directions to instruct the driving of the left-side driving motor 6, a driving control device (not shown) that the driver operates with their hands or feet in the forward and backward directions to instruct the driving of the right-side driving motor, and an attachment control device 17 (see Figure 2 below) that the driver operates with their feet to instruct the driving of the hydraulic breaker 10 (attachment). The attachment control device 17 corresponds to a second control device that can operate the hydraulic breaker 10.

[0017] On the right side of the driver's seat, there is a working operation device 18A (see FIG. 2 described later) that allows the driver to manually operate in the front-rear direction to instruct the drive of the boom cylinder 11 and manually operate in the left-right direction to instruct the drive of the attachment cylinder 13, and a key switch (not shown). On the left side of the driver's seat, there is a working operation device 18B (see FIG. 2 described later) that allows the driver to manually operate in the front-rear direction to instruct the drive of the arm cylinder 12 and manually operate in the left-right direction to instruct the drive of the swing motor 3, and a lock operation device 19 (see FIG. 2 described later). Note that the working operation device 18A corresponds to a first operation device capable of lowering and raising the boom 8.

[0018] The hydraulic excavator of the present embodiment includes a drive device that drives a plurality of hydraulic actuators (specifically, the swing motor 3, the left traveling motor 6, the right traveling motor, the hydraulic breaker 10, the boom cylinder 11, the arm cylinder 12, and the attachment cylinder 13). FIG. 2 is a diagram showing the configuration related to the drive of the swing motor 3, the hydraulic breaker 10, the boom cylinder 11, the arm cylinder 12, and the attachment cylinder 13 among the configurations of the drive device in the present embodiment. FIG. 3 is a block diagram showing the functional configuration of the controller shown in FIG. 2 together with related devices.

[0019] The drive device of the present embodiment includes an engine 20 as a prime mover, a hydraulic pump 21 (main pump) driven by the engine 20, a main relief valve 22 that limits the discharge pressure of the hydraulic pump 21, and a control valve unit 23. The control valve unit 23 has a swing control valve 24, an attachment drive control valve 25, a boom rotation control valve 26, an arm rotation control valve 27, and an attachment rotation control valve 28 that respectively control the flow of pressure oil from the hydraulic pump 21 to the swing motor 3, the hydraulic breaker 10, the boom cylinder 11, the arm cylinder 12, and the attachment cylinder 13.

[0020] The drive device of this embodiment includes a pilot pump 29 driven by an engine 20, a pilot relief valve 30 that restricts the discharge pressure of the pilot pump 29, electromagnetic proportional valves 31A and 31B for slewing that use the discharge pressure of the pilot pump 29 as the source pressure to generate a pilot pressure for operating the control valve 24 for slewing, electromagnetic proportional valves 32A and 32B for attachment drive that use the discharge pressure of the pilot pump 29 as the source pressure to generate a pilot pressure for operating the control valve 25 for attachment drive, electromagnetic proportional valves 33A and 33B for boom rotation that use the discharge pressure of the pilot pump 29 as the source pressure to generate a pilot pressure for operating the control valve 26 for boom rotation, electromagnetic proportional valves 34A and 34B for arm rotation that use the discharge pressure of the pilot pump 29 as the source pressure to generate a pilot pressure for operating the control valve 27 for arm rotation, electromagnetic proportional valves 35A and 35B for attachment rotation that use the discharge pressure of the pilot pump 29 as the source pressure to generate a pilot pressure for operating the control valve 28 for attachment rotation, and a controller 36 that controls the electromagnetic proportional valves 31A, 31B to 35A, 35B.

[0021] The attachment operation device 17 has, for example, an operation pedal operable by a driver and a potentiometer that detects the operation amount of the operation pedal and outputs a corresponding operation command value for breaker drive (attachment drive).

[0022] The controller 36 has a processor that executes control according to a program and a memory that stores the program and data. As a functional configuration, the controller 36 has an electromagnetic proportional valve control unit 37 and the like. The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table showing the relationship between the operation command value (current value) and the control command value (current value) regarding breaker drive, and that the control command value increases as the operation command value increases. When an operation command value for breaker drive is input from the attachment operation device 17, the corresponding control command value for breaker drive is obtained using the above-described control table and output to the electromagnetic proportional valve 32A for attachment drive.

[0023] The electromagnetic proportional valve 32A for attachment driving generates a pilot pressure corresponding to the control command value for breaker driving and outputs it to the pressure receiving section on the right side of the control valve 25 for attachment driving. The control valve 25 for attachment driving is switched to the switching position on the right side of the diagram and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the hydraulic breaker 10 via the control valve 25, and its flow rate is controlled to drive the hydraulic breaker 10. The electromagnetic proportional valve 32B for attachment driving is controlled when another attachment is installed in place of the hydraulic breaker 10.

[0024] The work control device 18A includes an operating lever that can be operated by the operator in the forward / backward and left / right directions, a potentiometer that detects the amount of forward movement of the operating lever and outputs a corresponding boom lowering operation command value, a potentiometer that detects the amount of rearward movement of the operating lever and outputs a corresponding boom raising operation command value, a potentiometer that detects the amount of leftward movement of the operating lever and outputs a corresponding breaker retraction operation command value, and a potentiometer that detects the amount of rightward movement of the operating lever and outputs a corresponding breaker push-out operation command value.

[0025] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to lowering the boom, indicating that the control command value increases as the operation command value increases. When an operation command value for lowering the boom is input from the work operation device 18A (in other words, when the boom 8 is lowered by the work operation device 18A), the controller uses the aforementioned control table to obtain the corresponding boom lowering control command value and outputs it to the electromagnetic proportional valve 33A for boom rotation.

[0026] The electromagnetic proportional valve 33A for boom rotation generates a pilot pressure corresponding to the boom lowering control command value and outputs it to the pressure receiving section on the right side of the boom rotation control valve 26 shown in the figure. The boom rotation control valve 26 is switched to the switching position on the right side of the figure and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the rod side of the boom cylinder 11 via the control valve 26, and its flow rate is controlled, causing the boom cylinder 11 to retract. Consequently, the boom 8 lowers (in other words, rotates downward).

[0027] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to raising the boom, indicating that the control command value increases as the operation command value increases. When an operation command value for raising the boom is input from the work operation device 18A (in other words, when the boom 8 is raised by the work operation device 18A), the controller uses the aforementioned control table to obtain the corresponding control command value for lowering the boom and outputs it to the electromagnetic proportional valve 33B for boom rotation.

[0028] The electromagnetic proportional valve 33B for boom rotation generates a pilot pressure corresponding to the boom raising control command value and outputs it to the pressure receiving section on the left side of the boom rotation control valve 26 shown in the figure. The boom rotation control valve 26 is switched to the switching position on the left side of the figure and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the bottom side of the boom cylinder 11 via the control valve 26, and its flow rate is controlled, causing the boom cylinder 11 to extend. Consequently, the boom 8 rises (in other words, rotates upward).

[0029] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to breaker pull-in, indicating that the control command value increases as the operation command value increases. When an operation command value for breaker pull-in is input from the work operation device 18A, the controller uses the aforementioned control table to obtain the corresponding control command value for breaker pull-in and outputs it to the electromagnetic proportional valve 35A for attachment rotation.

[0030] The electromagnetic proportional valve 35A for rotating the attachment generates a pilot pressure corresponding to the control command value for breaker retraction and outputs it to the pressure receiving section on the left side of the control valve 28 for rotating the attachment. The control valve 28 for rotating the attachment is switched to the switching position on the left side of the diagram and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the bottom side of the attachment cylinder 13 via the control valve 28, and its flow rate is controlled so that the attachment cylinder 13 extends. Consequently, the hydraulic breaker 10 is retracted (in other words, it rotates in the direction toward the slewing body 2).

[0031] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to breaker push-out, indicating that the control command value increases as the operation command value increases. When an operation command value for breaker push-out is input from the work operation device 18A, the controller uses the aforementioned control table to obtain the corresponding control command value for breaker push-out and outputs it to the electromagnetic proportional valve 35B for attachment rotation.

[0032] The electromagnetic proportional valve 35B for rotating the attachment generates a pilot pressure corresponding to the control command value for breaker push-out and outputs it to the pressure receiving section on the right side of the control valve 28 for rotating the attachment. The control valve 28 for rotating the attachment is switched to the switching position on the right side of the diagram and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the rod side of the attachment cylinder 13 via the control valve 28, and its flow rate is controlled, causing the attachment cylinder 13 to retract. Consequently, the hydraulic breaker 10 is pushed out (in other words, it rotates away from the slewing body 2).

[0033] The operating device 18B includes an operating lever that can be operated by the operator in the forward / backward and left / right directions, a potentiometer that detects the amount of forward movement of the operating lever and outputs a corresponding arm extension command value, a potentiometer that detects the amount of rearward movement of the operating lever and outputs a corresponding arm retraction command value, a potentiometer that detects the amount of leftward movement of the operating lever and outputs a corresponding left turn command value, and a potentiometer that detects the amount of rightward movement of the operating lever and outputs a corresponding right turn command value.

[0034] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to arm extension, indicating that the control command value increases as the operation command value increases. When an operation command value for arm extension is input from the work operation device 18B, the controller uses the aforementioned control table to obtain the corresponding control command value for arm extension and outputs it to the electromagnetic proportional valve 34A for arm rotation.

[0035] The electromagnetic proportional valve 34A for arm rotation generates a pilot pressure corresponding to the control command value for arm extension and outputs it to the pressure receiving section on the right side of the arm rotation control valve 27 shown in the figure. The arm rotation control valve 27 is switched to the switching position on the right side of the figure and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the rod side of the arm cylinder 12 via the control valve 27, and its flow rate is controlled, causing the arm cylinder 12 to retract. Consequently, the arm 9 is pushed out (in other words, it rotates away from the slewing body 2).

[0036] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to arm retraction, indicating that the control command value increases as the operation command value increases. When an operation command value for arm retraction is input from the work operation device 18B, the controller uses the aforementioned control table to obtain the corresponding control command value for arm retraction and outputs it to the electromagnetic proportional valve 34B for arm rotation.

[0037] The electromagnetic proportional valve 34B for arm rotation generates a pilot pressure corresponding to the control command value for arm retraction and outputs it to the pressure receiving section on the left side of the arm rotation control valve 27 shown in the figure. The arm rotation control valve 27 is switched to the switching position on the left side of the figure and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the bottom side of the arm cylinder 12 via the control valve 27, and its flow rate is controlled, causing the arm cylinder 12 to extend. Consequently, the arm 9 is retracted (in other words, it rotates in the direction toward the slewing body 2).

[0038] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to left turns, indicating that the control command value increases as the operation command value increases. When an operation command value for left turns is input from the work operation device 18B, the controller uses the aforementioned control table to obtain the corresponding control command value for left turns and outputs it to the electromagnetic proportional valve 31A for turning.

[0039] The electromagnetic proportional valve 31A for slewing generates a pilot pressure corresponding to the control command value for leftward rotation and outputs it to the pressure receiving section on the left side of the slewing control valve 24 shown in the figure. The slewing control valve 24 is switched to the switching position on the left side shown in the figure and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to one side of the slewing motor 3 via the control valve 24, and its flow rate is controlled so that the slewing motor 3 rotates in one direction. Consequently, the slewing body 2 rotates to the left.

[0040] The electromagnetic proportional valve control unit 37 of the controller 36 stores a control table that shows the relationship between the operation command value (current value) and the control command value (current value) related to right turns, indicating that the control command value increases as the operation command value increases. When an operation command value for a right turn is input from the work operation device 18B, the controller uses the aforementioned control table to obtain the corresponding control command value for a right turn and outputs it to the electromagnetic proportional valve 31B for turning.

[0041] The electromagnetic proportional valve 31B for slewing generates a pilot pressure corresponding to the control command value for rightward rotation and outputs it to the pressure receiving section on the right side of the slewing control valve 24 shown in the figure. The slewing control valve 24 is switched to the switching position on the right side of the figure and controlled to the flow path opening area corresponding to the pilot pressure. As a result, pressurized oil is supplied from the hydraulic pump 21 to the other side of the slewing motor 3 via the control valve 24, and its flow rate is controlled, causing the slewing motor 3 to rotate in the opposite direction. Consequently, the slewing body 2 rotates to the right.

[0042] Furthermore, the configuration for driving the left or right travel motor is almost the same as the configuration described above. That is, the control valve unit 23 further includes a travel control valve that controls the flow of pressurized oil from the hydraulic pump 21 to the travel motor. The drive device further includes a pair of travel electromagnetic proportional valves that generate pilot pressure to operate the travel control valve. When the controller 36 receives a forward operation command value from the travel operating device, it generates a corresponding forward operation command value and outputs it to one of the travel electromagnetic proportional valves, and when the travel operating device receives a reverse operation command value, it generates a corresponding reverse operation command value and outputs it to the other travel electromagnetic proportional valve. This switches the travel control valves and rotates the travel motor.

[0043] A lock valve 38 is provided in the oil passage between all solenoid proportional valves and the pilot pump 29. The lock valve 38 can be switched between a shut-off state, which shuts off all solenoid proportional valves and the pilot pump 29, and a connected state, which connects all solenoid proportional valves and the pilot pump 29. The controller 36 controls the lock valve 38 in accordance with the operation of the lock operating device 19.

[0044] The locking device 19 is provided, for example, at the entrance to the driver's cab 15 and includes a lock lever that can be operated to a raised position (locked position) that allows the driver to get on and off and a position that prevents the driver from getting on and off (unlocked position), and a lock switch that outputs a signal when the lock lever is operated to the unlocked position.

[0045] When no signal is received from the lock switch, the controller 36 does not output a drive signal to the lock valve 38, thereby shutting off the lock valve 38. This prevents all solenoid proportional valves from generating pilot pressure, thus prohibiting the operation of all hydraulic actuators. When a signal is received from the lock switch, the controller 36 outputs a drive signal to the lock valve 38, switching the lock valve 38 into a connected state. This enables all solenoid proportional valves to generate pilot pressure, thus allowing the operation of all hydraulic actuators.

[0046] A feature of this embodiment is that when a combined operation of lowering the boom 8 and driving the hydraulic breaker 10 is performed, the electromagnetic proportional valve control unit 37 of the controller 36 limits the boom lowering control command value and outputs it to the electromagnetic proportional valve 33A. Another feature of this embodiment is that, for example, a limit changeover switch 39 is provided inside the operator's cab 15 to switch between enabling and disabling the function of limiting the boom lowering control command value. When the function of limiting the boom lowering control command value is enabled by the limit changeover switch 39, the controller 36 limits the boom lowering control command value, and when the function of limiting the boom lowering control command value is disabled by the limit changeover switch 39, the controller 36 does not limit the boom lowering control command value. Details of this control will be explained with reference to Figure 4.

[0047] Figure 4 is a flowchart illustrating the control procedure of the controller in this embodiment. Note that the control shown in Figure 4 is performed when the engine 20 is running and the lock valve 38 is in communication.

[0048] In step S1, the limit determination unit 40 (see Figure 3) of the controller 36 determines whether the limit changeover switch 39 has been switched to enable the limit function. If the limit changeover switch 39 has been switched to disable the limit function, the limit determination unit 40 instructs the electromagnetic proportional valve control unit 37 to disable the limit function.

[0049] On the other hand, if the limiting switch 39 is switched to enable the limiting function, the limiting determination unit 40 instructs the electromagnetic proportional valve control unit 37 to enable the limiting function. Then, the process proceeds to step S2, where the electromagnetic proportional valve control unit 37 determines whether a boom lowering operation command value has been input from the work operation device 18A. If no boom lowering operation command value has been input from the work operation device 18A, the process returns to step S1 described above. On the other hand, if a boom lowering operation command value has been input from the work operation device 18A, the process proceeds to step S3.

[0050] In step S3, the electromagnetic proportional valve control unit 37 uses a control table for boom lowering to obtain a boom lowering control command value corresponding to the boom lowering operation command value. Then, proceeding to step S4, the electromagnetic proportional valve control unit 37 determines whether a breaker drive operation command value has been input from the attachment operation device 17 at the same time as the boom lowering operation command value input from the work operation device 18A mentioned above.

[0051] If the electromagnetic proportional valve control unit 37 does not receive an operation command value for lowering the boom from the work operation device 18A at the same time as an operation command value for driving the breaker from the attachment operation device 17 (i.e., a combined operation of lowering the boom 8 and driving the hydraulic breaker 10 is not performed), the process proceeds to step S5. In step S5, the electromagnetic proportional valve control unit 37 outputs the boom lowering control command value obtained in step S3 above to the electromagnetic proportional valve 32A for driving the attachment without limiting it. In this case, since the boom lowering control command value is not limited, the lowering speed of the boom 8 is not suppressed.

[0052] On the other hand, when the electromagnetic proportional valve control unit 37 receives an operation command value for lowering the boom from the work operation device 18A and an operation command value for driving the breaker from the attachment operation device 17 at the same time (i.e., when a combined operation of lowering the boom 8 and driving the hydraulic breaker 10 is performed), the process moves to step S6. In step S6, when the boom lowering control command value acquired in step S3 exceeds an upper limit (for example, 30% of the maximum value), the electromagnetic proportional valve control unit 37 corrects the boom lowering control command value to the upper limit, thereby limiting the boom lowering control command value. The limited boom lowering control command value is then output to the electromagnetic proportional valve 32A for driving the attachment. In this case, since the boom lowering control command value is limited, the lowering speed of the boom 8 is suppressed.

[0053] As described above, in this embodiment, when performing the combined operation of lowering the boom 8 and driving the hydraulic breaker 10, the lowering speed of the boom 8 is automatically adjusted. Therefore, it is possible to facilitate the combined operation of lowering the boom 8 and driving the hydraulic breaker 10 in the operation of crushing an object.

[0054] In addition, in the above embodiment, when the control command value for lowering the boom obtained using the control table exceeds the upper limit value (for example, 30% of the maximum value), the controller 36 corrects the control command value for lowering the boom to the upper limit value to limit the control command value for lowering the boom. However, the present invention is not limited to this example. For example, the controller 36 may limit the control command value for lowering the boom by multiplying the control command value for lowering the boom obtained using the control table by a correction coefficient C (where 0 < C < 1, for example, C = 0.3) for correction. Also in this case, it is possible to correct the control command value for lowering the boom so that it is below the upper limit value.

[0055] Further, in the above embodiment and the modification example, the upper limit value for the control command value for lowering the boom has been described by taking the case where it is fixed as an example, but the present invention is not limited to this, and it may be variable. That is, for example, as in the modification example shown in FIG. 5, the hydraulic excavator may include an upper limit value adjustment dial 41 for adjusting the upper limit value for the control command value for lowering the boom. The controller 36 limits the control command value for lowering the boom so that it is below the upper limit value adjusted by the upper limit value adjustment dial 41. More specifically, when the upper limit value adjustment unit 42 (see FIG. 6) of the controller 36 is switched to enable the limitation by the limit changeover switch 39, it instructs the electromagnetic proportional valve control unit 37 of the upper limit value adjusted by the upper limit value adjustment dial 41 (see step S7 in FIG. 7). In such a modification example, the operator can adjust the lowering speed of the boom 8 during the combined operation of lowering the boom 8 and driving the hydraulic breaker 10 by operating the upper limit value adjustment dial 41.

[0056] Furthermore, in the above embodiment, the attachment operating device 17 was described as being located in front of the driver's seat and configured to be operated by the driver with their feet, but it is not limited to this. The attachment operating device 17 may, for example, be provided on the gripping portion of the operating lever that constitutes the work operating device 18A or 18B and configured to be operated by the driver with their hands.

[0057] In the above description, a hydraulic excavator was used as an example of the applicable machinery of the present invention, but it is not limited to this, and other construction machines may also be used. [Explanation of Symbols]

[0058] 1. Running body 2. Rotating body 7. Work equipment The heroine boom 9 Arms 10 Hydraulic breakers 11 Boom Cylinder 17. Operating device for attachments 18A,18B Work operation device 21 Hydraulic pump 26 Control valve for boom rotation 33A, 33B Solenoid proportional valve for boom rotation 36 Controllers 39. Limit changeover switch 41 Upper limit adjustment dial

Claims

1. The car body and, A work device having a boom rotatably connected to the vehicle body, an arm rotatably connected to the boom, and a hydraulic breaker rotatably connected to the arm, A boom cylinder that rotates the boom relative to the vehicle body, Hydraulic pump and A control valve that controls the flow of pressurized oil from the hydraulic pump to the boom cylinder, A first solenoid proportional valve and a second solenoid proportional valve that generate pilot pressure to operate the control valve, A first operating device capable of lowering and raising the boom, A second operating device capable of driving the hydraulic breaker, A controller that, when the boom is lowered by the first operating device, acquires a boom lowering control command value corresponding to the boom lowering operation and outputs it to the first electromagnetic proportional valve, and when the boom is raised by the first operating device, acquires a boom raising control command value corresponding to the boom raising operation and outputs it to the second electromagnetic proportional valve, In construction machinery equipped with, The controller is characterized in that, when a combined operation of lowering the boom and driving the hydraulic breaker is performed, it limits the control command value for lowering the boom and outputs it to the first electromagnetic proportional valve.

2. In the construction machine described in claim 1, The system includes a limit switch that enables the function to limit the boom lowering control command value and disables the function to limit the boom lowering control command value. The controller is characterized in that, when the function to limit the boom lowering control command value is enabled by the limit switch, it limits the boom lowering control command value, and when the function to limit the boom lowering control command value is disabled by the limit switch, it does not limit the boom lowering control command value.

3. In the construction machine described in claim 1, It is equipped with an upper limit adjustment dial for adjusting the upper limit of the control command value for lowering the boom, The controller is characterized in that it limits the boom lowering control command value so that it is less than or equal to the upper limit value adjusted by the upper limit adjustment dial.

Images