Work machinery

Abstract

To provide a work machine in which a posture of a cab cannot be changed unless operated according to a predetermined procedure.SOLUTION: In response to satisfaction of a first condition that a shut-off operating section is in a blocking position, a second condition that a lock operating section is in a release position, and a third condition that a posture operating section is operated and, in addition, in response to a fact that the third condition is satisfied last, a controller supplies hydraulic oil to a second actuator to change a posture of a cab. In response to a fact that the first condition or the second condition is satisfied last, the controller notifies that an operating procedure for changing the cab's posture is incorrect through a notification device without supplying hydraulic oil to the second actuator.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a work machine equipped with a positionally adjustable cab. [Background technology]

[0002] Conventionally, work machines equipped with cabs that can change their position have been known. Specific examples of cabs that can change their position include a tilt cab that tilts so that the operator's line of sight is directed upward, a link cab that moves up and down while remaining horizontal, and a slide cab that slides back and forth while remaining horizontal.

[0003] The cab of the work machine is also equipped with operating devices (pedals, levers, etc.) for operating the travel motor, swing motor, and hydraulic cylinder of the front work machine (hereinafter collectively referred to as "hydraulic actuators"), as well as a shutoff lever that allows or prevents the supply of hydraulic oil to the hydraulic actuator, and a position change switch that commands a change in the position of the cab (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-32056 [Patent Document 2] Japanese Patent Publication No. 2020-51134 Summary of the Invention [Problem to be solved by the invention]

[0005] In such a work machine, if the position of the cab changes at a timing not intended by the operator, the operator may lose his balance and come into contact with the operating device, possibly activating other hydraulic actuators.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a work machine in which the position of the cab cannot be changed unless it is operated in accordance with a predetermined procedure. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a vehicle body having a working device, a cab supported on the vehicle body in a state in which its position can be changed to a first position and a second position, a first actuator that drives the working device by supplying and discharging hydraulic oil, a second actuator that changes the position of the cab by supplying and discharging hydraulic oil, a shutoff operation unit that is operated to an allowance position that allows the supply of hydraulic oil to the first actuator and a blocking position that blocks the supply of hydraulic oil to the first actuator, a lock operation unit that is operated to a lock position that locks the position change of the cab and a release position that releases the lock on the position change of the cab, and a position control unit that instructs the position change of the cab. In a work machine having an operating unit, an alarm device that notifies information, and a controller, the controller supplies hydraulic oil to the second actuator to change the attitude of the cab when all of the following conditions are met: a first condition that the shutoff operating unit is in the blocked position, a second condition that the lock operating unit is in the released position, and a third condition that the attitude operating unit has been operated, and when the third condition is met last, and notifies through the alarm device that the operating procedure for changing the attitude of the cab is incorrect without supplying hydraulic oil to the second actuator when the first condition or the second condition is met last. [Effects of the Invention]

[0008] According to the present invention, it is possible to obtain a work machine in which the position of the cab cannot be changed unless a predetermined procedure is followed. Note that problems, configurations, and effects other than those described above will become apparent from the description of the following embodiments. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a side view of a hydraulic excavator. [Figure 2] FIG. [Figure 3] FIG. 1 is a diagram showing a drive circuit mounted on a hydraulic excavator. [Figure 4] FIG. 2 is a control block diagram of the hydraulic excavator. [Figure 5] 10 is a flowchart showing a process when the shutoff lever is switched from the permitting position to the blocking position. [Figure 6] 10 is a flowchart showing a process when the lock switch is switched from the lock position to the release position. [Figure 7] 10 is a flowchart when the tilt switch is switched from the off position to the movable position. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of a hydraulic excavator 1 (work machine) according to the present invention will be described with reference to the drawings. Fig. 1 is a side view of the hydraulic excavator 1. Fig. 2 is a side view showing the attitude of the cab 7. Specific examples of the work machine are not limited to the hydraulic excavator 1, and may include a wheel loader, a crane, a dump truck, etc. Furthermore, unless otherwise specified, the terms front, back, left, and right in this specification are based on the viewpoint of an operator who is on board and operating the hydraulic excavator 1.

[0011] As shown in FIG. 1, the hydraulic excavator 1 includes a lower traveling body 2 and an upper rotating body 3 supported by the lower traveling body 2. The lower traveling body 2 and the upper rotating body 3 are an example of a vehicle body. The lower traveling body 2 includes a pair of left and right crawlers which are endless tracks. The pair of left and right crawlers rotate independently when driven by a traveling motor (not shown). As a result, the hydraulic excavator 1 travels. However, the lower traveling body 2 may be a wheeled type instead of a crawler type.

[0012] The upper rotating body 3 is supported on the lower traveling body 2 so as to be rotatable by a rotating motor (not shown). The upper rotating body 3 mainly comprises a rotating frame 5 serving as a base, a front working machine 4 (working device) attached to the front center of the rotating frame 5 so as to be rotatable in the vertical direction, a cab (operator's seat) 7 located on the front left side of the rotating frame 5, and a counterweight 6 located at the rear of the rotating frame 5.

[0013] The front working implement 4 includes a boom 4a supported on the upper rotating body 3 so that it can be raised and lowered, an arm 4b rotatably supported at the tip of the boom 4a, a bucket 4c rotatably supported at the tip of the arm 4b, a boom cylinder 4d that drives the boom 4a, an arm cylinder 4e that drives the arm 4b, and a bucket cylinder 4f that drives the bucket 4c. The counterweight 6 is used to balance the weight of the front working implement 4, and is a heavy object that has an arc shape when viewed from above.

[0014] The cab 7 is supported by the revolving frame 5 in a state in which its position can be changed. The cab 7 is a so-called "tilt cab" that can change its position between a horizontal position (first position) shown in Fig. 2(A) and a tilt position (second position) shown in Fig. 2(B).

[0015] More specifically, a tower 10 is erected on the upper surface of the revolving frame 5 behind the cab 7. The cab 7 is fixed onto a bed 11. The cab 7 is configured to be rotatable around a connecting pin 12 that extends in the left-right direction at the upper end of the tower 10. The hydraulic excavator 1 is also equipped with a cab cylinder 13 that expands and contracts by supplying and discharging hydraulic oil. One end of the cab cylinder 13 is rotatably supported by a boss 14 provided at the lower end of the tower 10, and the other end is rotatably supported by a boss 15 provided on the bed 11.

[0016] Then, as the cab cylinder 13 contracts, the cab 7 assumes a horizontal position as shown in FIG. 2(A). The horizontal position is a position in which the underside (reference plane) of the cab 7 faces horizontally. That is, an operator sitting in the cab 7 in the horizontal position can easily see what is ahead in the horizontal direction. Furthermore, as the cab cylinder 13 extends, the cab 7 assumes a tilt position as shown in FIG. 2(B). The tilt position is a position in which the front end of the underside of the cab 7 is positioned higher than the rear end. That is, an operator sitting in the cab 7 in the tilt position can easily see what is ahead in the upward direction.

[0017] The travel motor, the swing motor, the boom cylinder 4d, the arm cylinder 4e, and the bucket cylinder 4f are examples of first actuators that operate (extend and retract, rotate) by supplying and discharging hydraulic oil. Also, the cab cylinder 13 is an example of a second actuator that operates (extend and retract) by supplying and discharging hydraulic oil. However, specific examples of the first actuator and the second actuator are not limited to these.

[0018] The cab 7 also has an internal space in which an operator who operates the hydraulic excavator 1 sits. The internal space of the cab 7 is provided with a seat on which the operator sits and an operating device that is operated by the operator seated in the seat. The operating device receives operations from the operator to operate the hydraulic excavator 1. When the operator operates the operating device, the lower traveling body 2 travels, the upper rotating body 3 rotates, and the front working implement 4 operates. Specific examples of the operating device include a lever, a steering wheel, an accelerator pedal, a brake pedal, and a switch.

[0019] The operation device includes a travel pedal that commands the drive of the travel motor, a swing lever that commands the drive of the swing motor, a boom lever that commands the drive of the boom cylinder, an arm lever that commands the drive of the arm cylinder, and a bucket lever that commands the drive of the bucket cylinder, as well as a shutoff lever 16 (shutoff operation unit), a lock switch 17 (lock operation unit), and a tilt switch 18 (posture operation unit) as shown in FIG. 4.

[0020] The shutoff lever 16 is configured to be switchable between an allowable position and a blocked position by being operated by the operator. The allowable position is a position that allows the supply of hydraulic oil to the travel motor, swing motor, boom cylinder 4d, arm cylinder 4e, and bucket cylinder 4f. The blocked position is a position that blocks the supply of hydraulic oil to the travel motor, swing motor, boom cylinder 4d, arm cylinder 4e, and bucket cylinder 4f. The shutoff lever 16 outputs a shutoff signal indicating the current position to a controller 50 (see FIG. 4), which will be described later.

[0021] The lock switch 17 is configured to be switchable between a locked position and an unlocked position by being operated by the operator. The locked position is a position where the cab 7 is locked from changing its position. The unlocked position is a position where the lock on the cab 7 from changing its position is unlocked. The lock switch 17 is a so-called alternate switch that maintains its current position even after the operator has finished operating it. The lock switch 17 outputs a lock signal indicating the current position to the controller 50.

[0022] The tilt switch 18 is configured to be switchable between an off position, a tilt-up position, and a tilt-down position by being operated by an operator. The off position is a position where no command is issued to change the position of the cab 7. The tilt-up position corresponds to an command to change the position of the cab 7 toward a tilt position. The tilt-down position corresponds to an command to change the position of the cab 7 toward a horizontal position.

[0023] The tilt-up position and the tilt-down position are, for example, positions on opposite sides of the OFF position. The tilt switch 18 is a so-called momentary switch that returns to the OFF position when the operator finishes operating it. The tilt switch 18 outputs an attitude change signal indicating the current position to the controller 50.

[0024] Fig. 3 is a diagram showing a drive circuit mounted on the hydraulic excavator 1. The drive circuit shown in Fig. 3 is a circuit that drives the boom cylinder 4d and the cab cylinder 13. Although not shown, the hydraulic excavator 1 also includes drive circuits that drive the travel motor, the swing motor, the arm cylinder 4e, and the bucket cylinder 4f. As shown in Fig. 2, the hydraulic excavator 1 mainly includes an engine 20, a hydraulic oil tank 21, a main pump 22, a pilot pump 23, a cab pump 24, directional control valves 25 and 26, pilot control valves 27a, 27b, 28a, and 28b, and a shutoff valve 29.

[0025] The engine 20 generates driving force for driving the hydraulic excavator 1. The hydraulic oil tank 21 stores hydraulic oil. The main pump 22, the pilot pump 23, and the cab pump 24 are hydraulic pumps that are rotated by the driving force of the engine 20 and pump out the hydraulic oil stored in the hydraulic oil tank 21. The hydraulic oil pumped out from the main pump 22 is supplied to the boom cylinder 4d. The hydraulic oil pumped out from the pilot pump 23 is supplied to pilot ports 25a, 25b, 26a, and 26b of directional control valves 25 and 26. The hydraulic oil pumped out from the cab pump 24 is supplied to the cab cylinder 13.

[0026] The directional control valve 25 is disposed in the flow path leading from the main pump 22 to the boom cylinder 4d. The directional control valve 25 supplies the hydraulic oil supplied from the main pump 22 to the boom cylinder 4d, and returns the hydraulic oil discharged from the boom cylinder 4d to the hydraulic oil tank 21.

[0027] The directional control valve 25 has a spool that moves between a shut-off position A, an extended position B, and a retracted position C. The shut-off position A is a position that shuts off the supply and discharge of hydraulic oil to the boom cylinder 4d. The extended position B is a position that supplies hydraulic oil to the bottom chamber of the boom cylinder 4d and returns hydraulic oil discharged from the rod chamber to the hydraulic oil tank 21, thereby extending the boom cylinder 4d. The retracted position C is a position that supplies hydraulic oil to the rod chamber of the boom cylinder 4d and returns hydraulic oil discharged from the bottom chamber to the hydraulic oil tank 21, thereby retracting the boom cylinder 4d.

[0028] The initial position of the spool of the directional control valve 25 is the shutoff position A. Furthermore, the directional control valve 25 moves from the shutoff position A toward the extended position B when pilot pressure oil is supplied to the pilot port 25a and the pilot pressure oil is discharged from the pilot port 25b. Furthermore, the directional control valve 25 moves from the shutoff position A toward the retracted position C when pilot pressure oil is supplied to the pilot port 25b and the pilot pressure oil is discharged from the pilot port 25a.

[0029] The directional control valve 26 is disposed in a flow path leading from the carburetor pump 24 to the carburetor cylinder 13. The directional control valve 26 supplies the hydraulic oil supplied from the carburetor pump 24 to the carburetor cylinder 13, and returns the hydraulic oil discharged from the carburetor cylinder 13 to the hydraulic oil tank 21.

[0030] The directional control valve 26 has a spool that moves between a shutoff position A, an extended position B, and a retracted position C. The shutoff position A is a position that shuts off the supply and discharge of hydraulic oil to the carburetor cylinder 13. The extended position B is a position that supplies hydraulic oil to the bottom chamber of the carburetor cylinder 13 and returns hydraulic oil discharged from the rod chamber to the hydraulic oil tank 21, thereby extending the carburetor cylinder 13. The retracted position C is a position that supplies hydraulic oil to the rod chamber of the carburetor cylinder 13 and returns hydraulic oil discharged from the bottom chamber to the hydraulic oil tank 21, thereby retracting the carburetor cylinder 13.

[0031] The initial position of the spool of the directional control valve 26 is the shutoff position A. Furthermore, the directional control valve 26 moves from the shutoff position A toward the extended position B when pilot pressure oil is supplied to the pilot port 26a and the pilot pressure oil is discharged from the pilot port 26b. Furthermore, the directional control valve 26 moves from the shutoff position A toward the retracted position C when pilot pressure oil is supplied to the pilot port 26b and the pilot pressure oil is discharged from the pilot port 26a.

[0032] The pilot control valves 27a and 27b are arranged on the flow paths leading from the pilot pump 23 to the pilot ports 25a and 25b. Since the pilot control valves 27a and 27b have the same configuration, only the pilot control valve 27a will be described below.

[0033] The pilot control valve 27a has a spool that moves between a supply position D and a return position E in accordance with operation of a boom lever that commands drive of the boom cylinder. The supply position D is a position where the pilot pressure oil supplied from the pilot pump 23 is supplied to the pilot port 25a. The return position E is a position where the pilot pressure oil discharged from the pilot port 25a is returned to the hydraulic oil tank 21. The initial position of the spool of the pilot control valve 27a is the return position E. Then, when the boom lever is operated, the spool moves from the return position E to the supply position D.

[0034] The pilot control valves 28a and 28b are disposed in the flow paths leading from the pilot pump 23 to the pilot ports 26a and 26b. Since the pilot control valves 28a and 28b have the same configuration, only the pilot control valve 28a will be described below.

[0035] The pilot control valve 28a is an electromagnetic proportional valve whose spool moves between a supply position D and a return position E under the control of the controller 50. The supply position D is a position where the pilot pressure oil supplied from the pilot pump 23 is supplied to the pilot port 26a. The return position E is a position where the pilot pressure oil discharged from the pilot port 26a is returned to the hydraulic oil tank 21. The initial position of the spool of the pilot control valve 28a is the return position E. Then, when a command current is supplied from the controller 50, the spool moves from the return position E to the supply position D.

[0036] The shutoff valve 29 is disposed in a flow path from the pilot pump 23 to the pilot control valves 27a, 27b. The shutoff valve 29 is an electromagnetic proportional valve whose spool moves between a shutoff position F and a supply position G under the control of the controller 50. The shutoff position F is a position where the pilot pressure oil supplied from the pilot pump 23 is not supplied to the pilot control valves 27a, 27b but is returned to the hydraulic oil tank 21. The supply position G is a position where the pilot pressure oil supplied from the pilot pump 23 is supplied to the pilot control valves 27a, 27b. The initial position of the spool of the shutoff valve 29 is the shutoff position F. When a command current is supplied from the controller 50, the spool moves from the shutoff position F to the supply position G.

[0037] Fig. 4 is a control block diagram of the hydraulic excavator 1. As shown in Fig. 4, the hydraulic excavator 1 is equipped with a controller 50 having a CPU (Central Processing Unit) 51 and a memory 52. ​​The memory 52 is configured, for example, by a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination of these. The controller 50 realizes the processing described below by having the CPU 51 read and execute program code stored in the memory 52.

[0038] However, the specific configuration of the controller 50 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0039] The controller 50 controls the overall operation of the hydraulic excavator 1. Based on a shutoff signal output from the shutoff lever 16, a lock signal output from the lock switch 17, and an attitude change signal output from the tilt switch 18, the controller 50 rotates the engine 20 and the hydraulic pumps 22, 23, 24, and opens and closes (outputs a command current for) the pilot control valves 28a to 28b and the shutoff valve 29. The controller 50 also activates the cab in-cab alarm unit 31 and the cab outside alarm unit 32 based on a combination of signals output from the operating devices.

[0040] The cab in-cab notification unit 31 is an example of a notification device that is installed inside the cab 7 and notifies information to an operator riding in the cab 7. The cab in-cab notification unit 31 is, for example, a display, an LED lamp, a speaker, or a combination of these. The cab outside notification unit 32 is another example of a notification device that is installed on the outer surface of the hydraulic excavator 1 and notifies information to workers working around the hydraulic excavator 1. The cab outside notification unit 32 is, for example, an LED lamp, a speaker, or a combination of these.

[0041] In response to the shutoff lever 16 being operated to the permitting position, the controller 50 switches the shutoff valve 29 to the supply position G. As a result, the pilot pressure oil supplied from the pilot pump 23 is supplied to the pilot control valves 27a and 27b.

[0042] Next, when the boom lever is operated, the controller 50 switches one of the pilot control valves 27a, 27b to the supply position D. This causes pilot pressure oil to be supplied to either the pilot port 25a, 25b, and the direction control valve 25 is switched to the extension position B or the retraction position C. As a result, hydraulic oil is supplied to or discharged from the main pump 22 to the boom cylinder 4d, causing it to extend or retract.

[0043] Meanwhile, in response to the shutoff lever 16 being operated to the blocking position, the controller 50 switches the shutoff valve 29 to the shutoff position F. As a result, the pilot pressure oil supplied from the pilot pump 23 is returned to the hydraulic oil tank 21 without being supplied to the pilot control valves 27a, 27b.

[0044] Next, one of the pilot control valves 28a, 28b is switched to the supply position D, whereby the directional control valve 26 is switched to the extension position B or the retraction position C. As a result, the carburetor cylinder 13 is supplied with hydraulic oil from the carburetor pump 24 and discharged, thereby expanding and contracting.

[0045] On the other hand, because pilot pressure oil is not supplied to pilot control valves 27a and 27b, even if the boom lever is operated, directional control valve 25 remains in shut-off position A. As a result, hydraulic oil is not supplied to or discharged from main pump 22 to boom cylinder 4d. In other words, shut-off position F of shut-off valve 29 is a position that shuts off the supply of hydraulic oil to boom cylinder 4d.

[0046] Furthermore, the controller 50 generally controls the pilot control valves 28a, 28b as follows: First, in response to the tilt switch 18 being operated to the OFF position, the controller 50 switches both of the pilot control valves 28a, 28b to the recirculation position E. In response to the tilt switch 18 being operated to the tilt-up position, the controller 50 switches the pilot control valve 28a to the supply position D and the pilot control valve 28b to the recirculation position E. In response to the tilt switch 18 being operated to the tilt-down position, the controller 50 switches the pilot control valve 28a to the recirculation position E and the pilot control valve 28b to the supply position D.

[0047] However, if the shut-off lever 16, lock switch 17, and tilt switch 18 are operated in any order and the cab cylinder 13 expands or contracts, the position of the cab 7 may change at a timing not intended by the operator. As a result, if the operator loses balance inside the cab 7, his or her body may come into contact with other operating devices, causing the hydraulic excavator 1 to perform an unintended operation.

[0048] 5 to 7, the control based on the operating sequence of the shut-off lever 16, lock switch 17, and tilt switch 18 will be described. FIG. 5 is a flowchart when the shut-off lever 16 is switched from the allowable position to the blockable position. FIG. 6 is a flowchart when the lock switch 17 is switched from the lock position to the release position. FIG. 7 is a flowchart when the tilt switch 18 is switched from the off position to the movable position. In FIGS. 5 to 7, the tilt-up position and tilt-down position of the tilt switch 18 are collectively referred to as the "movable position."

[0049] 5, in response to the shutoff lever 16 being operated from the permitting position to the blocking position, the controller 50 switches the shutoff valve 29 to the blocking position F (S11). Next, the controller 50 determines whether the lock switch 17 is in the release position or not based on the lock signal output from the lock switch 17 (S12). Then, in response to the lock switch 17 being in the release position (S12: Yes), the controller 50 determines whether the tilt switch 18 is in the movable position or not based on the tilt signal output from the tilt switch 18 (S13).

[0050] Then, in response to the shut-off lever 16 being operated to the blocking position with the lock switch 17 in the release position and the tilt switch 18 in the movable position (S12: Yes & S13: Yes), the controller 50 notifies through the cab in-cab notification unit 31 that the operating procedure for changing the position of the cab 7 is incorrect (S14). At this time, in step S34 in Fig. 7 described later, even if the tilt switch 18 is operated to the movable position, the pilot control valves 28a, 28b remain held at the recirculation position E, so the cab cylinder 13 does not expand or contract (the position of the cab 7 does not change).

[0051] Furthermore, in response to the shutoff lever 16 being operated to the blocking position with the lock switch 17 in the release position and the tilt switch 18 in the off position (S12: Yes & S13: No), the controller 50 notifies the cab outside alarm unit 32 that there is a possibility that the position of the cab 7 will change (S15). Furthermore, in response to the shutoff lever 16 being operated to the blocking position with the lock switch 17 in the lock position (S12: No), the controller 50 ends the processing of FIG. 5 without executing the processing from step S13 onwards.

[0052] In steps S14 and S15, the controller 50 stops the notification by the cab inside notification unit 31 and the cab outside notification unit 32 in response to the shutoff lever 16 being operated to the permitting position or the lock switch 17 being operated to the lock position. The same applies to steps S23 and S24 in Fig. 6, which will be described later.

[0053] 6, in response to the lock switch 17 being operated from the lock position to the release position, the controller 50 determines whether the shutoff lever 16 is in the blocked position based on the shutoff signal output from the shutoff lever 16 (S21). Then, in response to the shutoff lever 16 being in the blocked position (S21: Yes), the controller 50 determines whether the tilt switch 18 is in the movable position based on the tilt signal output from the tilt switch 18 (S22).

[0054] Then, in response to the lock switch 17 being operated to the release position with the shut-off lever 16 in the blocking position and the tilt switch 18 in the movable position (S21: Yes & S22: Yes), the controller 50 notifies through the cab in-cab notification unit 31 that the operating procedure for changing the position of the cab 7 is incorrect (S23). At this time, in step S34 in Fig. 7 described later, even if the tilt switch 18 is operated to the movable position, the pilot control valves 28a, 28b remain held at the recirculation position E, so the cab cylinder 13 does not expand or contract (the position of the cab 7 does not change).

[0055] Furthermore, in response to the lock switch 17 being operated to the release position while the shutoff lever 16 is in the blocking position and the tilt switch 18 is in the off position (S21: Yes & S22: No), the controller 50 notifies the cab outside alarm unit 32 that there is a possibility that the position of the cab 7 will change (S24). Furthermore, in response to the lock switch 17 being operated to the release position while the shutoff lever 16 is in the allowing position (S21: No), the controller 50 ends the processing of FIG. 6 without executing the processing from step S22 onwards.

[0056] 7, in response to the tilt switch 18 being operated from the OFF position to the movable position, the controller 50 determines whether the shutoff lever 16 is in the blocked position based on the shutoff signal output from the shutoff lever 16 (S31). Also, the controller 50 determines whether the lock switch 17 is in the released position based on the lock signal output from the lock switch 17 (S32).

[0057] Then, in response to the tilt switch 18 being operated to the movable position (S31: Yes & S32: Yes) with the shut-off lever 16 in the blocking position and the lock switch 17 in the release position, the controller 50 switches one of the pilot control valves 28a, 28b (the side corresponding to the operating direction of the tilt switch 18) to the supply position D (S33). As a result, hydraulic oil is supplied from the cab pump 24 to the cab cylinder 13, and the attitude of the cab 7 changes.

[0058] On the other hand, when the shut-off lever 16 is in the permitting position or the lock switch 17 is in the locking position and the tilt switch 18 is operated to the movable position (S31: No / S32: No), the controller 50 holds both of the pilot control valves 28a, 28b at the return position E. This prevents hydraulic oil from being supplied from the cab pump 24 to the cab cylinder 13. As a result, as in steps S14 and S23 described above, the attitude of the cab 7 does not change even if the tilt switch 18 is operated.

[0059] A condition in which the shut-off lever 16 is in the blocking position is defined as a "first condition," a condition in which the lock switch 17 is in the lock position is defined as a "second condition," and a condition in which the tilt switch 18 is operated to the movable position is defined as a "third condition." At this time, the controller 50 supplies hydraulic oil to the cab cylinder 13 to change the position of the cab 7 in response to all of the first, second, and third conditions being satisfied and the third condition being satisfied last. On the other hand, the controller 50 does not supply hydraulic oil to the cab cylinder 13 in response to the first or second condition being satisfied last, and notifies the driver through the cab in-cab notification unit 31 that the operating procedure for changing the position of the cab 7 is incorrect.

[0060] According to the above embodiment, for example, the following advantageous effects are achieved.

[0061] According to the above embodiment, when the shutoff lever 16 is operated to the blocking position and the lock switch 17 is operated to the release position with the tilt switch 18 operated to the movable position, the cab in-cab notification unit 31 is activated without changing the position of the cab 7. This allows the operator to recognize that the position of the cab 7 cannot be changed unless the operator operates it in accordance with a predetermined procedure.

[0062] Furthermore, according to the above embodiment, when the shutoff lever 16 is operated to the allowable position or the lock switch 17 is operated to the lock position while the cab interior notification unit 31 is activated, the notification by the cab interior notification unit 31 stops. This makes it possible to prevent the cab interior notification unit 31 from being activated even when the operator does not intend to change the position of the cab 7.

[0063] Furthermore, according to the above embodiment, the position of the cab 7 changes only when the shutoff lever 16, lock switch 17, and tilt switch 18 are operated in a predetermined order. As a result, it is possible to prevent an operator who loses his balance due to an unintended change in the position of the cab 7 from touching other operating devices and activating other hydraulic actuators. Note that the order in which the shutoff lever 16 and lock switch 17 are operated to change the position of the cab 7 is not particularly limited.

[0064] The present invention can be applied not only to tilt cabs but also to link cabs and slide cabs. As an example, in the case of a link cab, the first position and the second position are positions spaced apart in the up-down direction. As another example, in the case of a slide cab, the first position and the second position are positions spaced apart in the front-rear direction.

[0065] The above-described embodiments are merely illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the present invention. [Explanation of symbols]

[0066] 1. Hydraulic excavator 2 Undercarriage (car body) 3 Upper rotating body (car body) 4 Front work equipment 4a Boom 4b Arm 4c Bucket 4d Boom cylinder (first actuator) 4e Arm cylinder (first actuator) 4f Bucket cylinder (first actuator) 5 Swivel frame 6 Counterweight 7 Cab 10. Tower 11 beds 12 connecting pin 13 Carburetor cylinder (second actuator) 14,15 Boss 16 Shut-off lever (shut-off operation part) 17 Lock switch (lock operation part) 18 Tilt switch (attitude control unit) 20 Engine 21 Hydraulic oil tank 22 Main pump 23 Pilot pump 24 Carburetor pump 25,26 Directional control valve 25a, 25b, 26a, 26b Pilot ports 27a, 27b, 28a, 28b Pilot control valve 29 Shut-off valve 31 Cab alarm unit (alarm device) 32 Cab outside alarm unit 50 Controllers 51 CPU 52 memory

Claims

1. a vehicle body having a working device; a cab supported on the vehicle body in a state in which the cab can be changed between a first position and a second position; a first actuator that drives the working device by supplying and discharging hydraulic oil; a second actuator that changes the position of the cab by supplying or discharging hydraulic oil; a shutoff operation unit that is operated to a permitting position that permits the supply of hydraulic oil to the first actuator and a blocking position that blocks the supply of hydraulic oil to the first actuator; a lock operation unit that is operated to a lock position that locks the cab from changing its position and to an unlock position that unlocks the cab from changing its position; a posture control unit that instructs a posture change of the cab; Controller and In a work machine comprising: The controller supplying hydraulic oil to the second actuator to change the attitude of the cab when all of a first condition that the shutoff operation unit is in the blocking position, a second condition that the lock operation unit is in the release position, and a third condition that the attitude operation unit is operated are satisfied, and when the third condition is satisfied last; When the first condition, the second condition, and the third condition are all satisfied and the first condition or the second condition is satisfied last, hydraulic oil is not supplied to the second actuator. A work machine characterized by:

2. 2. The work machine according to claim 1, A notification device is provided to notify information, The controller When the first condition, the second condition, and the third condition are all satisfied and the first condition or the second condition is satisfied last, a warning is given through the warning device that the operating procedure for changing the attitude of the cab is incorrect without supplying hydraulic oil to the second actuator. A work machine characterized by:

3. 3. The work machine according to claim 2, The controller During the execution of the notification through the notification device, the notification through the notification device is stopped in response to the shutoff operation unit being operated from the blocking position to the permitting position or in response to the lock operation unit being operated from the release position to the lock position. A work machine characterized by:

4. 3. The work machine according to claim 2, The first posture is a posture in which a reference surface of the cab faces a horizontal direction, The second attitude is an attitude in which the front end of the reference plane is positioned higher than the rear end. A work machine characterized by:

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