331, hydraulic oil from a hydraulic pump to be driven by the engine, and adjusts a magnitude of power to be supplied to the bucket 331 by adjusting a flow rate of the hydraulic oil.

As illustrated in FIG. 4, the driving unit 34 is a space for allowing an operator to get in, and is located above the turning unit 32 in the present embodiment. Therefore, when the turning unit 32 turns in a plan view, the driving unit 34 also turns together with the turning unit 32. Specifically, in a case where the turning unit 32 is divided into two parts in the left-right direction D3, the driving unit 34 is provided in a left portion of the turning unit 32. The driving unit 34 includes at least the driver's seat 341 in which an operator is seated.

As a kind of the driving unit 34 of the work machine 3 such as a construction machine, there are a cabin type, a canopy type, a floor type, and the like. The driving unit 34 of a cabin type includes a cabin, and an operator gets in a cabin space inside the cabin. The driving unit 34 of a canopy type includes a canopy (roof), and an operator gets in a space below the canopy. The driving unit 34 of a floor type does not include the cabin, a canopy, and the like, and an operator gets in a space opened upward. That is, the driving unit 34 may include not only a configuration in which surroundings are surrounded by a panel or the like, but also various configurations prepared as a space that an operator can get in. In the present embodiment, a case where the driving unit 34 is a cabin type is described as an example.

In the present embodiment, the driving unit 34 is located above the left crawler 311 (see FIG. 1). This arrangement allows an operator to get in and out of the driving unit 34 from the left side of the driving unit 34. Therefore, in the present embodiment, a door of the driving unit 34 is disposed on the left side of the driving unit 34 in the left-right direction D3. That is, an operator gets in and out of the driving unit 34 through a door disposed on the left side of the driving unit 34.

The operation system 2 is installed in the driving unit 34 of the machine body 30, and is a user interface for accepting an operation input by a user (operator), and operating the work machine 3. As illustrated in FIG. 4, the operation system 2 includes the operation lever 21 for operating the soil removal device 35, a pair of levers 342 disposed at both sides of the driver's seat 341 in the left-right direction D3, and the like.

The pair of levers 342 are located on both sides of a front end portion of the driver's seat 341 in the left-right direction D3. Therefore, an operator seated in the driver's seat 341, for example, holds one of the levers 342 with his/her right hand, holds the other of the levers 342 with his/her left hand, and causes the work machine 3 to perform various movements by operating the pair of levers 342.

The operation lever 21 is located on one side of the front end portion of the driver's seat 341 in the left-right direction D3. Herein, the operation lever 21 is located outside of the pair of levers 342. In the present embodiment, as an example, the operation lever 21 is located further on the right side of the right lever 342, that is, on a side opposite to the driver's seat 341 when viewed from the lever 342. Therefore, an operator in a seated state in the driver's seat 341 holds the operation lever 21, for example, with his/her right hand, and causes (the blade 351 of) the soil removal device 35 to perform various movements by operating the operation lever 21. Details on the operation lever 21 are described in the column “[3] Configuration of Operation Lever”.

The display device 51 is disposed in the driving unit 34, and is a user interface for outputting various pieces of information to an operator. The display device 51 is controlled by the control system 1, and presents (outputs) various pieces of information by displaying various screens. The display device 51 may include a function of outputting sounds (including voice), in addition to display, and present various pieces of information by sounds. Further, in the present embodiment, the display device 51 includes an input means such as a touch panel, and accepts various operations by an operator by outputting an electrical signal in response to an operator's operation. This allows an operator to visually recognize a display screen to be displayed on the display device 51, and operate the display device 51 according to needs.

In addition to the above-described configuration, the machine body 30 further includes a control device, a sound output unit, a communication terminal, a cutoff lever, a fuel tank, a battery, various sensors for detecting a detection target object in a monitoring area around the work machine 3, such as a camera that images surroundings of the machine body 30, and the like. Further, the machine body 30 includes sensors (including a camera) for monitoring an operating condition of the machine body 30, such as a cooling water temperature sensor, a hydraulic oil temperature sensor, a tachometer that measures a rotational speed of the engine, and an hour meter that measures working hours.

[2] Configuration of Hydraulic Circuit

Next, a configuration of a hydraulic circuit of the work machine 3 according to the present embodiment is described with reference to FIG. 5. In FIG. 5, solid lines represent high-pressure oil paths (for hydraulic oil), dotted lines represent low-pressure oil paths (for pilot oil), and dashed-dotted line arrows represent electric signal paths.

As illustrated in FIG. 5, the work machine 3 includes the angle cylinder 353, the tilt cylinder 354, the hydraulic pump 41, a direction switching valve (control valve) 42, a switching valve 43, a plurality of control valves 441 to 445, and a plurality of shuttle valves 451 and 452. The work machine 3 further includes, as the operation system 2, an automatic control unit 22, a driver 23, a controller 24, and a cutoff lever 25, in addition to the above-described operation lever 21. FIG. 5 illustrates a hydraulic circuit associated with the angle cylinder 353 that causes the blade 351 to perform angle movement, and the tilt cylinder 354 that causes the blade 351 to perform tilt movement, and illustration of other hydraulic circuits is omitted as necessary.

The direction switching valve 42 is a pilot-type direction switching valve capable of switching a direction and a flow rate of hydraulic oil from the hydraulic pump 41, and is driven by supply of a pilot signal (pilot oil) serving as an input command from a pilot pump. Specifically, the direction switching valve 42 switches whether to flow hydraulic oil from the hydraulic pump 41 to the switching valve 43. The four control valves 441 to 444 are provided on a pilot oil supply path to the direction switching valve 42.

The control valves 441 and 442 are connected to the direction switching valve 42 via the shuttle valve 451, and the control valves 443 and 444 are connected to the direction switching valve 42 via the shuttle valve 452. Therefore, a pilot signal on a high-pressure side between the control valves 441 and 442 is input to the direction switching valve 42, and a pilot signal on a high-pressure side between the control valves 443 and 443 is input to the direction switching valve 42.

The switching valve 43 switches a supply destination of hydraulic oil from the hydraulic pump 41 between the angle cylinder 353 and the tilt cylinder 354 via the direction switching valve 42. The control valve 445 is provided on a pilot oil supply path to the switching valve 43. That is, the control valve 445 can switch a supply destination of hydraulic oil from the hydraulic pump 41 between the angle cylinder 353 and the tilt cylinder 354.

Any of the control valves 441 to 445 is constituted of an electromagnetic control valve (solenoid valve). Herein, it is assumed that each of the control valves 441 to 445 is a (solenoid type) proportional control valve. However, the embodiment is not limited thereto, and any of the control valves 441 to 445 may be, for example, an on/off valve capable of switching open/shut-off of a flow path.

The control valves 441 and 443 are electrically connected to the driver 23, and operated in response to a control signal from the driver 23. The control valves 442 and 444 are electrically connected to the automatic control unit 22, and operated in response to a control signal from the automatic control unit 22. The control valve 445 is electrically connected to the driver 23, and operated in response to a control signal from the driver 23.

Herein, as illustrated in FIG. 5, the operation system 2 includes a first operation element 201, a second operation element 202, a third operation element 203, and a fourth operation element 204. Although details will be described later, in the present embodiment, as an example, any of the first operation element 201, the second operation element 202, the third operation element 203, and the fourth operation element 204 is provided on the operation lever 21. Any of the first operation element 201, the second operation element 202, the third operation element 203, and the fourth operation element 204 is an electric-type operation element, and accepts various operations by an operator by outputting an electrical signal (operation signal) in response to an operator's operation.

The first operation element 201 and the second operation element 202 are electrically connected to the driver 23. The fourth operation element 204 is electrically connected to the automatic control unit 22.

At an operation time of the first operation element 201 or the second operation element 202, the driver 23 controls the control valves 441 and 443 in response to an operation of the first operation element 201 or the second operation element 202 in such a way as to open the control valves 441 and 443. Further, at an operation time of the first operation element 201, the driver 23 controls the control valve 445 in response to an operation of the first operation element 201 in such a way as to open the control valve 445.

Meanwhile, the automatic control unit 22 switches between an automatic control mode and a manual control mode in response to an operation of the fourth operation element 204. In the automatic control mode, the automatic control unit 22 automatically controls the control valves 442 and 444 so as to automatically perform at least tilt movement of the blade 351.

The controller 24 includes, as a main component, a computer system including, for example, one or more processors such as a central processing unit (CPU), and one or more memories such as a read only memory (ROM) and a random access memory (RAM), and executes various pieces of processing (information processing). In the present embodiment, the controller 24 is an integral controller that performs overall control of the work machine 3, and is, for example, configured of an electronic control unit (ECU). However, the controller 24 may be provided independently of an integral controller, or may include, as a main component, one processor or a plurality of processors.

In the present embodiment, as an example, since the controller 24 includes, as a main component, a computer system including one or more processors, various functions as the controller 24 are achieved by causing the one or more processors to execute a control program. The plurality of functions included in the controller 24 may be provided in a plurality of housings in a distributive manner, or may be provided in one housing. For example, the plurality of functions included in the controller 24 may be provided in the automatic control unit 22 and/or the driver 23, or conversely, at least some of the functions of the automatic control unit 22 and/or the driver 23 may be provided in the controller 24.

In the present embodiment, as described above, at an operation time of the first operation element 201 or the second operation element 202, by controlling at least the driver 23, the controller 24 causes the driver 23 to control the control valves 441 and 443 in response to an operation of the first operation element 201 or the second operation element 202 in such a way as to open the control valves 441 and 443. Further, at an operation time of the first operation element 201, the controller 24 causes the driver 23 to control the control valve 445 in response to an operation of the first operation element 201 in such a way as to open the control valve 445.

The cutoff lever 25 switches between a locked state in which movement of the work machine 3 is restricted, and a lock released state in which movement of the work machine 3 is not restricted. The cutoff lever 25 is disposed in the driving unit 34 of the machine body 30, and accepts an operation input by an operator. In the present embodiment, as an example, the cutoff lever 25 is operable along the up-down direction D1. In a case where the cutoff lever 25 is at an “up position” being an upper end position in a movable range, the work machine 3 is brought to a locked state. On the other hand, in a case where the cutoff lever 25 is at a “down position” being a lower end position in the movable range, the work machine 3 is brought to a lock released state.

Specifically, in a locked state in which the cutoff lever 25 is at an “up position”, by closing a control valve provided on a pilot signal (pilot oil) supply path from a pilot pump, a hydraulic actuator is forcibly stopped. Therefore, to drive the hydraulic actuator, an operator is required to operate the cutoff lever 25 to a “down position”. As far as the cutoff lever 25 is at an “up position”, all of the traveling unit 31, the turning unit 32, the work unit 33, and the soil removal device 35 are brought to a forcible driving disabled state (locked state). The cutoff lever 25 is a lever to be operated when movement of the work machine 3 is locked as described above, and is equivalent to a gate lock lever.

[3] Configuration of Operation Lever

Next, a configuration of the operation lever 21 according to the present embodiment is described with reference to FIG. 6. In FIG. 6, only the operation lever 21 is illustrated, and illustration of the other components is omitted.

In the present embodiment, since the operation lever 21 is an operation tool of a lever type, a pose (such as an orientation) of the operation lever 21 is changed as necessary by an operation accompanying movement of a grip portion 211. Therefore, a pose of the operation lever 21 may be changed as necessary with respect to the up-down direction D1, the front-rear direction D2, and the left-right direction D3 that are determined with respect to the machine body 30 of the work machine 3, as a reference. In the following, as illustrated in FIG. 6, a pose of the operation lever 21 is described based on an assumption that a longitudinal direction of the grip portion 211 coincides with the up-down direction D1, and an operation surface 212 of the grip portion 211 is in a state facing rearward.

The operation lever 21 includes the grip portion 211, the first operation element 201, the second operation element 202, the third operation element 203, and the fourth operation element 204.

The grip portion 211 is a portion to be gripped by an operator, and, in the present embodiment, as an example, has a shape having a length in one direction (up-down direction D1). The operation lever 21 is capable of accepting a lifting operation accompanying movement of the grip portion 211. A “lifting operation” mentioned herein is an operation for causing the blade 351 of the soil removal device 35 to perform lifting movement. That is, the operation lever 21 accepts a lifting operation for causing the blade 351 to perform lifting movement.

Upon accepting a lifting operation in such a way as to move the grip portion 211 along the front-rear direction D2 by an operator, the operation lever 21 performs a lifting operation by the lifting cylinder 352 in such a way as to raise and lower the blade 351 according to an operation amount of the operation lever 21. In the present embodiment, as described above, as an example, since the operation lever 21 is disposed on the right side of the driver's seat 341, normally, the operation lever 21 is operated by the right hand of an operator seated in the driver's seat 341.

The grip portion 211 includes the operation surface 212 on one surface thereof. The operation surface 212 is a surface on which the first operation element 201, the second operation element 202, and the third operation element 203 are disposed. In the present embodiment, as an example, the operation surface 212 is provided, on a surface of the grip portion 211, on a side of an operator seated in the driver's seat 341, that is, on a portion (back surface) facing rearward. Herein, the operation surface 212 is a flat surface, but the operation surface 212 is not limited to a flat surface, and may include, for example, a curved surface, a step, or the like.

The fourth operation element 204 is provided on a surface of the grip portion 211 opposite to the side of the operation surface 212 of the grip portion 211, that is, on a portion (front surface) facing rearward. In this way, the first operation element 201, the second operation element 202, the third operation element 203, and the fourth operation element 204 are provided on the grip portion 211 of the operation lever 21.

Any of the first operation element 201, the second operation element 202, the third operation element 203, and the fourth operation element 204 is constituted of a mechanical switch such as a slide switch, a seesaw switch, a push button switch, or a joystick. In the present embodiment, as an example, each of the first operation element 201 and the second operation element 202 is a slide switch, and each of the third operation element 203 and the fourth operation element 204 is a push button switch. Herein, the following operation is allocated to each of the first operation element 201, the second operation element 202, the third operation element 203, and the fourth operation element 204.

An angle operation for causing the blade 351 to perform angle movement is allocated to the first operation element 201. That is, angle movement of the blade 351 is performed according to an operation direction and an operation amount of the first operation element 201 constituted of a slide switch.

A tilt operation for causing the blade 351 to perform tilt movement is allocated to the second operation element 202. That is, tilt movement of the blade 351 is performed according to an operation direction and an operation amount of the second operation element 202 constituted of a slide switch.

A vehicle speed switching operation for switching a vehicle speed of the traveling unit 31 of the work machine 3 is allocated to the third operation element 203. That is, a vehicle speed of the traveling unit 31 is switched by a plurality of stages including a first gear and a second gear, each time the third operation element 203 constituted of a push button is pushed.

A mode switching operation for switching between the automatic control mode and the manual control mode of the automatic control unit 22 is allocated to the fourth operation element 204. That is, the automatic control mode in which the automatic control unit 22 automatically controls the blade 351, and the manual control mode in which the blade 351 is manually controlled are switched, each time the fourth operation element 204 constituted of a push button switch is pushed. Herein, only tilt movement and lifting movement of the blade 351 are automatically controlled in the automatic control mode, and angle movement of the blade 351 is not automatically performed.

As described above, the operation system 2 according to the present embodiment is the operation system 2 for the work machine 3 provided with the soil removal device 35 including the blade 351, and includes the operation lever 21, the first operation element 201, and the second operation element 202. The operation lever 21 accepts a lifting operation for causing the blade 351 to perform lifting movement. The first operation element 201 accepts an operation (angle operation) for causing the blade 351 to perform angle movement of rotationally swinging the blade 351 around the first axis Ax1 along a vertical direction (up-down direction D1). The second operation element 202 accepts an operation (tilt operation) for causing the blade 351 to perform tilt movement of rotationally swinging the blade 351 around the second axis Ax2 along a horizontal direction. Herein, the first operation element 201 and the second operation element 202 are provided individually.

That is, the first operation element 201 for accepting an angle operation, and the second operation element 202 for accepting a tilt operation are provided independently of each other. Therefore, for example, in a case where tilt movement is performed after angle movement is performed, like a case where an angle operation and a tilt operation are allocated to a single operation element, it is not necessary to perform an operation (operation of a cylinder selection switch) for switching a function of the operation element. Therefore, an operation is made easy to an operator, and it is less likely that an erroneous operation resulting from misunderstanding of a cylinder in selection (the angle cylinder 353/the tilt cylinder 354) may occur. Consequently, according to the operation system 2, there is an advantage that it is easy to improve operability of the soil removal device 35.

Further, as illustrated in FIG. 6, the first operation element 201 and the second operation element 202 are disposed adjacent to each other. That is, the first operation element 201 and the second operation element 202 are disposed in proximity to each other on a same surface, and in a state in which another operation element does not intervene between the first operation element 201 and the second operation element 202. This makes it easy for an operator to operate the first operation element 201 and the second operation element 202 with the same finger, despite that the first operation element 201 and the second operation element 202 are provided individually, and operability of the first operation element 201 and the second operation element 202 is improved.

Further, the first operation element 201 and the second operation element 202 are disposed on the grip portion 211 of the operation lever 21. Thus, operations associated with the blade 351 are consolidated on the operation lever 21, which makes it easy for an operator to intuitively recognize an operation of the blade 351.

Further, the first operation element 201 and the second operation element 202 are disposed side by side in a longitudinal direction (up-down direction D1) of the grip portion 211. In the present embodiment, as an example, the first operation element 201 is located at a lower position, and the second operation element 202 is located at an upper position. Therefore, an operator can operate the first operation element 201 and the second operation element 202, while gripping substantially with the same hand, by sliding the hand in a longitudinal direction of the grip portion 211. Therefore, an operator can smoothly perform a shift between an angle operation and a tilt operation, which enables to perform a more intuitive operation.

Herein, the operation surface 212 of the grip portion 211 on which the first operation element 201 and the second operation element 202 are provided is inclined toward the driver's seat 341 in the left-right direction D3 of the machine body 30. In summary, in the present embodiment, as illustrated in FIG. 4, since the operation lever 21 is provided on the right side of the driver's seat 341, the operation surface 212 is inclined toward the left side (the side of the driver's seat 341) in the left-right direction D3. This allows an operator to smoothly perform a shift between an angle operation and a tilt operation, while performing an angle operation and a tilt operation with the same finger (e.g., the thumb (first finger)), which enables to perform a more intuitive operation.

Further, in the present embodiment, as described above, the third operation element 203 is further provided, in addition to the first operation element 201 and the second operation element 202. That is, the operation system 2 according to the present embodiment includes the third operation element 203 that is disposed on the grip portion 211, and accepts an operation of switching a vehicle speed of the traveling unit 31 of the work machine 3. This allows an operator to intuitively perform an operation of changing a vehicle speed, when operating the soil removal device 35 by the operation lever 21.

More specifically, the third operation element 203 is disposed, on the operation surface 212, at a lower position of the first operation element 201 and the second operation element 202. Further, the third operation element 203 is disposed, on the operation surface 212, on a side opposite to the driver's seat 341 (in the present embodiment, on the right side) with respect to the first operation element 201 and the second operation element 202. That is, as illustrated in FIG. 6, the third operation element 203 is disposed at a position close to the right side on the operation surface 212. This makes it easy for an operator to perform an operation of the soil removal device 35 by the first operation element 201 or the second operation element 202, and an operation of changing a vehicle speed by the third operation element 203 without mistake.

Further, in the present embodiment, as described above, the fourth operation element 204 is further provided, in addition to the first operation element 201 and the second operation element 202. That is, the operation system 2 according to the present embodiment includes the fourth operation element 204 that is disposed on the grip portion 211, and accepts an operation for automatically controlling the blade 351 of the soil removal device 35. This allows an operator to intuitively perform an operation of automatically controlling the blade 351, when operating the soil removal device 35 by the operation lever 21.

More specifically, the fourth operation element 204 is disposed, on the grip portion 211, on a surface opposite to the side of the operation surface 212 on which the first operation element 201 and the second operation element 202 are provided. This makes it easy for an operator to perform an operation for manually controlling the blade 351 by the first operation element 201 or the second operation element 202, and an operation for automatically controlling the blade 351 by the fourth operation element 204 without mistake.

In the present embodiment, each of the first operation element 201 and the second operation element 202 is a slide switch operable in both of operation directions with respect to a neutral position, as a reference. That is, as illustrated in FIG. 6, any of the first operation element 201 and the second operation element 202 is a slide switch which is in a neutral position in a non-operation state, and is operable in both of operation directions from the neutral position. Further, in the first operation element 201, a rotation amount (rotation angle) of the blade 351 in angle movement is determined according to an operation amount from the neutral position, and in the second operation element 202, a rotation amount (rotation angle) of the blade 351 in tilt movement is determined according to an operation amount from the neutral position.

According to this configuration, an operator can intuitively perform each of an angle operation and a slide operation, which improves operability. Particularly, determining a rotation amount of the blade 351 according to an operation amount from the neutral position enables to intuitively perform an angle operation and a tilt operation.

Further, the operation direction (of the first operation element 201 and the second operation element 202) is a direction along the left-right direction D3 of the machine body 30. That is, as illustrated in FIG. 6, any of the first operation element 201 and the second operation element 202 is operable from the neutral position in both of the left-right direction D3 (leftward and rightward). In the present embodiment, as an example, when the first operation element 201 is operated rightward, the blade 351 performs angle movement in such a way that a right end portion thereof is located rearward (a left end portion thereof is located forward), and when the first operation element 201 is operated leftward, the blade 351 performs angle movement in such a way that the left end portion thereof is located rearward (the right end portion thereof is located forward). When the second operation element 202 is operated rightward, the blade 351 performs tilt movement in such a way that the right end portion thereof is located downward (the left end portion thereof is located upward), and when the second operation element 202 is operated leftward, the blade 351 performs tilt movement in such a way that the left end portion thereof is located downward (the right end portion thereof is located upward).

This allows an operator to more intuitively perform each of an angle operation and a slide operation, which improves operability.

[4] Movement of Operation System

Next, movement of the operation system 2 according to the present embodiment is described with reference to FIGS. 5 and 7.

FIG. 7 is a state transition diagram indicating a transition condition of a state of the operation system 2. In FIG. 7, an arrow indicates a transition of a state, and, for example, a transition T1 represents a transition from <state 1> to <state 2>, and a transition T4 represents a transition from <state 3> to <state 1>.

Herein, <state 0> is a state (locked state) in which the cutoff lever 25 is at an up position, and any of <state 1> to <state 6> is a state (lock released state) in which the cutoff lever 25 is at a down position. Further, <state 1> is a state in which both of the first operation element 201 and the second operation element 202 are not operated (at a neutral position), and <state 5> is a simultaneous operated state in which both of the first operation element 201 and the second operation element 202 are simultaneously operated. <State 2> is a state in which the first operation element 201 is operated rightward, and <state 3> is a state in which the first operation element 201 is operated leftward. <State 4> is a state in which the second operation element 202 is operated rightward, and <state 5> is a state in which the second operation element 202 is operated leftward. <State 2> to <state 5> are a single operated state in which one of the first operation element 201 and the second operation element 202 is operated.

First, movement of the operation system 2 in a state (lock released state) in which the cutoff lever 25 is at a down position is described.

When a transition (T1, T3) is made from <state 1> in which both of the first operation element 201 and the second operation element 202 are not operated to <state 2> or <state 3> by a single operation of the first operation element 201, the controller 24 controls the control valve 445 by the driver 23, and switches the switching valve 43 to the side of the angle cylinder 353. Further, the controller 24 controls the control valves 441 and 443 by the driver 23 according to an operation amount of the first operation element 201, controls the direction switching valve 42, and supplies hydraulic oil from the hydraulic pump 41 to the angle cylinder 353 via the direction switching valve 42 and the switching valve 43. Thus, the angle cylinder 353 is driven according to an operation amount of the first operation element 201 that accepts an angle operation, and angle movement of the blade 351 is achieved.

Likewise, when a transition (T5, T7) is made from <state 1> in which both of the first operation element 201 and the second operation element 202 are not operated to <state 4> or <state 5> by a single operation of the second operation element 202, the controller 24 controls the control valve 445 by the driver 23, and switches the switching valve 43 to the side of the tilt cylinder 354. Further, the controller 24 controls the control valves 441 and 443 by the driver 23 according to an operation amount of the second operation element 202, controls the direction switching valve 42, and supplies hydraulic oil from the hydraulic pump 41 to the tilt cylinder 354 via the direction switching valve 42 and the switching valve 43. Thus, the tilt cylinder 354 is driven according to an operation amount of the second operation element 202 that accepts a tilt operation, and tilt movement of the blade 351 is achieved.

When a transition (T2, T4, T6, T8) is made from a single operated state <states 2 to 5> of the first operation element 201 or the second operation element 202 to <state 1> in which both of the first operation element 201 and the second operation element 202 are not operated, the controller 24 controls the control valves 441 and 443 by the driver 23, controls the direction switching valve 42, stops supply of hydraulic oil from the hydraulic pump 41 to the angle cylinder 353 or the tilt cylinder 354, and stops angle movement or tilt movement of the blade 351.

On the other hand, when a transition (T9) is made from <state 1> in which both of the first operation element 201 and the second operation element 202 are not operated to <state 6> by operations of both of the first operation element 201 and the second operation element 202, the controller 24 controls the control valves 441 and 443 by the driver 23, controls the direction switching valve 42, prohibits supply of hydraulic oil from the hydraulic pump 41 to the angle cylinder 353 and the tilt cylinder 354, and prohibits angle movement and tilt movement of the blade 351. Thus, at a simultaneous operation time of the first operation element 201 and the second operation element 202, both of angle movement and tilt movement of the blade 351 are prohibited.

When a transition (T10) is made from a simultaneous operated state (state 6) of the first operation element 201 and the second operation element 202 to <state 1> in which both of the first operation element 201 and the second operation element 202 are not operated, the controller 24 continues a state in which supply of hydraulic oil to the angle cylinder 353 and the tilt cylinder 354 is prohibited by the driver 23. Thus, a state in which both of angle movement and tilt movement of the blade 351 are prohibited is continued.

Further, when a transition (T11 to T14) is made from a single operated state (states 2 to 5) of the first operation element 201 or the second operation element 202 to a simultaneous operated state (state 6) of the first operation element 201 and the second operation element 202, the controller 24 controls the control valves 441 and 443 by the driver 23, controls the direction switching valve 42, prohibits supply of hydraulic oil from the hydraulic pump 41 to the angle cylinder 353 and the tilt cylinder 354, and prohibits angle movement and tilt movement of the blade 351. Thus, both of angle movement and tilt movement of the blade 351 are prohibited, even in a case where a transition is made from a single operated state of the first operation element 201 and the second operation element 202 to a simultaneous operated state of the first operation element 201 and the second operation element 202.

Further, in the present embodiment, in a case where a transition (TO) is made from a locked state (state 0) in which the cutoff lever 25 is at an up position to a lock released state by an operation of the cutoff lever 25 to a down position, a transition to <state 1> is made without fail. Thus, even in a case where the cutoff lever 25 is operated from an up position to a down position in a state in which one of the first operation element 201 and the second operation element 202 is operated, a single operated state (states 2 to 5) of the first operation element 201 or the second operation element 202 is prohibited, and both of angle movement and tilt movement of the blade 351 are prohibited.

As described above, in the operation system 2 according to the present embodiment, angle movement and tilt movement are prohibited at a simultaneous operation time (state 6) of the first operation element 201 and the second operation element 202. This makes it easy to prevent an unintended manual operation of the blade 351 by an operator due to a simultaneous operation of the individually provided first operation element 201 and second operation element 202.

Further, when a transition is made from a single operated state (states 2 to 5) in which one of the first operation element 201 and the second operation element 202 is operated to a simultaneous operated state (state 6) in which both of the first operation element 201 and the second operation element 202 are operated, angle movement and tilt movement are prohibited. This makes it easy to securely prevent an unintended manual operation of the blade 351 by an operator due to a simultaneous operation of the individually provided first operation element 201 and second operation element 202.

Further, in the present embodiment, a transition from a simultaneous operated state (state 6) of the first operation element 201 and the second operation element 202 to a single operated state (states 2 to 5) of the first operation element 201 or the second operation element 202 is not allowed. In summary, angle movement and tilt movement are prohibited, also in a single operated state in a case where a transition is made from a simultaneous operated state to a single operated state. This enable to more securely prevent an unintended manual operation of the blade 351 by an operator.

Further, the operation system 2 according to the present embodiment includes the cutoff lever 25 that switches between a locked state in which movement of the work machine 3 is restricted, and a lock released state in which movement of the work machine 3 is not restricted. Herein, angle movement and tilt movement are prohibited also in a case where the operation system 2 is switched from a locked state to a lock released state during continuation of a single operated state. This enables to more securely prevent an unintended manual operation of the blade 351 by an operator.

Herein, a transition detection time for detecting transitions T1 to T14 by the controller 24 can be set (adjusted) as a parameter. However, transitions (T11 to T14) from a single operated state (states 2 to 5) of the first operation element 201 or the second operation element 202 to a simultaneous operated state (state 6) of the first operation element 201 and the second operation element 202 assume a condition in which an erroneous operation is performed. Therefore, it is preferable to set a transition detection time for the transitions T11 to T14 long, as compared with the other transitions T1 to T10.

In the operation system 2 according to the present embodiment, the automatic control unit 22 automatically controls the blade 351 in the automatic control mode. Specifically, the automatic control unit 22 performs automatic control of lifting movement and tilt movement of the blade 351, based on a difference between design data, and an actual measurement value about the blade 351 to be measured by an angle sensor, a height sensor, and the like of the blade 351.

In this way, when one of the first operation element 201 and the second operation element 202 is operated in a state in which the automatic control unit 22 is in the automatic control mode, the automatic control unit 22 stops automatic control of the blade 351.

Specifically, as illustrated in FIG. 4, the four control valves 441 to 444 are provided on a pilot oil supply path to the direction switching valve 42 via the shuttle valves 451 and 452. Therefore, a pilot signal on a high-pressure side between the control valves 441 and 442 is input to the direction switching valve 42, and a pilot signal on a high-pressure side between the control valves 443 and 444 is input to the direction switching valve 42.

Normally, as far as the automatic control unit 22 is in the automatic control mode, the control valves 442 and 444 are on a high-pressure side. Therefore, pilot oil is supplied, to the direction switching valve 42, from the control valves 442 and 444 to be automatically controlled by the automatic control unit 22. In this state, when one of the first operation element 201 and the second operation element 202 is operated, the control valves 441 and 443 are brought to a high-pressure side, and pilot oil is supplied, to the direction switching valve 42, from the control valves 441 and 443 to be controlled by the driver