CONTROL DEVICE, OPERATION DEVICE, CONTROL METHOD, AND WORK VEHICLE

The control device is a control device that controls a drawbar attached to a main frame of a grader, in which a movement of the drawbar is generated by at least three actuators, and the control device controls, based on an output signal from one operation lever having at least three degrees of freedom, the plurality of actuators such that a movement of the one operation lever corresponds to the movement of the drawbar.

TECHNICAL FIELD

The present invention relates to a control device, an operation device, a control method, and a work vehicle.

Priority is claimed on Japanese Patent Application No. 2021-060559, filed on Mar. 31, 2021, the content of which is incorporated herein by reference.

BACKGROUND ART

A grader work equipment consists of a blade, a circle, a drawbar, lifters, and the like, and a plurality of actuators are provided for positioning them (for example, Patent Literature 1). For example, there are three actuators that control a movement of the drawbar, the left and right blade lift cylinders and the drawbar shift cylinder, but in order to achieve a desired angle, three axes operations spanning a plurality of operation levers is required, which poses a challenge because the operation is complicated and difficult.

CITATION LIST

Patent Literature

United States Patent Application, Publication No. 2020/0173135

SUMMARY OF INVENTION

Technical Problem

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device, an operation device, a control method, and a work vehicle that can be easily operated.

Solution to Problem

In order to solve the above problems, one aspect of the present invention is a control device that controls a drawbar attached to a main frame of a grader, in which a movement of the drawbar is generated by at least three actuators, and the control device controls, based on an output signal from one operation lever having at least three degrees of freedom, the plurality of actuators such that a movement of the one operation lever corresponds to the movement of the drawbar.

In addition, another aspect of the present invention is an operation device including the control device and the operation lever.

In addition, another aspect of the present invention is a control method for controlling a drawbar attached to a main frame of a grader, in which a movement of the drawbar is generated by at least three actuators, the control method including controlling, based on an output signal from one operation lever having at least three degrees of freedom, the plurality of actuators such that a movement of the one operation lever corresponds to the movement of the drawbar.

In addition, still another aspect of the present invention is a work vehicle including a main frame, a drawbar attached to the main frame and restrained to the main frame by a ball shaft, three actuators attached to the main frame to determine a posture of the drawbar, one operation lever operated by an operator, and a control device that controls the actuators based on an output signal from the operation lever, in which the control device controls the actuators such that a movement of the operation lever corresponds to the movement of the drawbar.

Advantageous Effects of Invention

According to each aspect of the present invention, an operation can be simplified.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each figure, the same reference numerals are used for the same or corresponding configurations, and the description thereof will be omitted as appropriate.

<Overview of Work Machine>

FIG.1is a perspective view showing a work machine1according to the embodiment.FIG.2is a perspective view showing a basic configuration example of a work equipment10of the work machine1according to the embodiment. The work machine1according to the embodiment is, for example, a motor grader (also simply referred to as a grader). In the following description, the work machine1will be referred to as a motor grader1as appropriate. In addition, the motor grader1is an example of a work vehicle.FIG.1andFIG.2are different models.

In the present embodiment, as shown inFIG.1, with reference to a vehicle main body2of the motor grader1, a vehicle width direction is defined as a left-right direction, a vertical direction orthogonal to the left-right direction is defined as an up-down direction, and then a vehicle length direction orthogonal to the left-right direction and the up-down direction is defined as a front-rear direction.

As shown inFIG.1, the motor grader1includes a vehicle main body2, a cab3, a traveling device4, and a work equipment10. The motor grader1travels a work site by using the traveling device4. In the work site, the motor grader1performs work by using the work equipment10. The motor grader1can perform work such as road construction (cutting and shaping of roadbed, subgrade, and slope), road maintenance and repair (cutting a gravel road, leveling gravel), snow removal (removal of accumulated and compacted snow), and other work (such as ground leveling of the square, trenching, and weeding) using the work equipment10. The work machine1, as long as it includes the work equipment10including a drawbar (pulling rod, towing rod) in which a movement is generated by at least three actuators, is not limited to the motor grader1.

The cab3is supported by the vehicle main body2. The cab3is internally provided with a driver's seat31on which an operator is seated and an operator operation device (not shown) operated by the operator to operate the motor grader1.

The traveling device4supports the vehicle main body2. In the present embodiment, the traveling device4includes two rotatable front wheels5and four rear wheels6. The motor grader1is capable of traveling on a road surface RS by the front wheels5and the rear wheels6of the traveling device4. The traveling device of the work machine is not limited to the wheels, and may be a crawler belt or the like.

The work equipment10is supported by the vehicle main body2. As shown inFIGS.1and2, the work equipment10includes a main frame11, a drawbar12, a circle13, a blade14, a right blade lift cylinder15, a left blade lift cylinder16, a drawbar shift cylinder17, a lifter21, a lifter22, a ball shaft23, a blade shift cylinder24, a power tilt cylinder25, and a circle rotation motor26. The right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17are three actuators that generate a movement of the drawbar12. The right blade lift cylinder15, the left blade lift cylinder16, the drawbar shift cylinder17, the blade shift cylinder24, and the power tilt cylinder25are hydraulic cylinders. In addition, the circle rotation motor26is a hydraulic motor. However, the present invention is not limited to a hydraulic cylinder or a hydraulic motor.

The main frame11is a holding unit that supports each unit, is composed of two subframes pin-coupled near the cab3and can be refracted (articulated).

The blade14is supported to enable shift and tilt with respect to the drawbar12, and performs excavating, earthmoving, and shaping. The circle13is a large gear having teeth on the inner side, which holds the blade14and rotates in the direction of arrow A6by the circle rotation motor26. In this case, the blade14is attached to the drawbar12.

The drawbar12is pivotally and rotatably (hereinafter, referred to as pivotally) restrained to the main frame11at an end portion of the drawbar12via one ball shaft23, supporting the circle13and receiving a traction force. The ball shaft23is also called a ball coupling, a ball joint, or the like, and connects the main frame11and the drawbar12. In this case, the drawbar12is attached to the main frame11of the motor grader1. Further, the drawbar12is restrained by the main frame11and one ball shaft23.

The right blade lift cylinder15is pivotally supported to the main frame11via the lifter21at its intermediate portion, and pivotally supported to the drawbar12at one end portion of the right blade lift cylinder15, extending and retracting in the direction of arrow A1. The left blade lift cylinder16is pivotally supported to the main frame11via the lifter22at its intermediate portion, and pivotally supported to the drawbar12at one end portion of the left blade lift cylinder16, extending and retracting in the direction of arrow A2. The drawbar shift cylinder17is pivotally supported to the main frame11at one end portion, and is pivotally supported to the drawbar12at the other end portion, extending and retracting in the direction of arrow A3. The right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17control the position and posture of the drawbar12.

The blade shift cylinder24is connected to the drawbar12at one end portion and supported by the blade14at the other end portion, extending and retracting in the direction of arrow A4to laterally shift the blade14. The power tilt cylinder25is connected to the drawbar12at one end portion and supported by the blade14at the other end portion, changing a cutting angle of the blade14in the rotation direction of arrow A5. The cutting angle is the angle formed between the cutting edge of the blade14and the road surface RS when the blade14is in contact with the road surface (ground) RS.

<Drawbar Control and Input Operation>

In the present embodiment, when controlling the position and posture of the drawbar12, a rotation direction α is defined with the up-down direction indicated by arrow Az as a rotation axis, a rotation direction β with the front-rear direction indicated by arrow Ay as a rotation axis, and a rotation direction γ with the left-right direction indicated by arrow Ax as a rotation axis, in which the three directions indicate the directions with respect to the ball shaft23which serves as a restraint point of the drawbar12, taking the pivotal and rotational center of the ball shaft23as an origin. The linear movements of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17are controlled by considering them as three axes rotational movements around the ball shaft23. In addition, an operator's input operation when operating the drawbar12is performed using a joy stick32(FIG.3andFIG.4), which is an example of one operation lever having at least three degrees of freedom.

FIG.3is a perspective view showing a configuration example of an operator operation device according to one embodiment of the present invention.FIG.4is a schematic diagram for describing an operation example of a joy stick32shown inFIG.3. In the example shown inFIG.3, in the cab3, a joy stick32is provided on the right side of the driver's seat31and a joy stick34is provided on the left side of the driver's seat31. In the present embodiment, the joy stick32is used as an operation input device when controlling the position and posture of the drawbar12, and the joy stick34is used as, for example, an operation input device when controlling the traveling device4. As shown inFIG.4, the joy stick32includes a lever32L, the lever32L is tiltable at least in the front-rear direction and the left-right direction, and rotatable around the up-down direction as a rotation axis. The tilting direction is not limited to two directions, and for example, may be tiltable in all directions. Further, the lever32L is held in a neutral state (upright state) when the operator is not operating the joy stick32, and the joy stick32further includes a dead zone region that ignores tilting or rotating within a certain range from the neutral state. In the present embodiment, a rotation direction αj around the axis in the up-down direction of the joy stick32is defined as an operation input corresponding to the rotation direction α shown inFIG.2, and a rotation direction βj around the axis in the front-rear direction of the joy stick32is defined as an operation input corresponding to the rotation direction3shown inFIG.2, and a rotation direction γj around the axis in the left-right direction of the joy stick32is defined as an operation input corresponding to the rotation direction γ shown inFIG.2.

The joy stick32further includes a slide switch33. The slide switch33is an example of an operation unit that operates a movement of the blade14of the motor grader1and the operator can slide the blade14left or right by sliding the slide switch33left or right.

The joy stick32outputs, for example, signals representing rotation angles αj, βj, and γj (or signals representing change amounts Δαj, Δβj, and Δγj of rotation angles αj, βj, and γj per a predetermined time) according to an operation state of the lever32L. In addition, the joy stick32outputs a signal representing the amount of sliding of the slide switch33.

<Configuration of Control System>

FIG.5is a block diagram showing a configuration example of a control system300of the motor grader1according to the embodiment. The control system300is an example of an operation device. As shown inFIG.2, the motor grader1includes a power source201, a Power Take Off (PTO)202, a traveling device4, a hydraulic pump203, a hydraulic control valve unit204, and a controller100. The control system300may further include the joy stick32or the slide switch33. The controller100is an example of a control device, and can be configured using, for example, a computer such as a microcomputer, and its peripheral circuits and peripheral devices, and various functions are implemented by a combination of hardware such as a computer and software such as programs executed by the computer.

The power source201generates the power for operating the work machine1. An internal combustion engine or an electric motor is an example of the power source201. The power source201is not limited to the internal combustion engine or the electric motor. For example, the power source201may be a so-called hybrid device in which the internal combustion engine, a generator motor, and a power storage device are combined. In addition, the power source201may have a configuration in which the power storage device and the generator motor are combined without having the internal combustion engine.

The PTO202transmits at least a portion of the power of the power source201to the hydraulic pump203. The PTO202distributes the power of the power source201to the traveling device4and the hydraulic pump203.

The traveling device4includes, for example, a transmission, a drive shaft, a brake, rear wheels6, and the like. Front wheels5are driven by, for example, a hydraulic motor (not shown).

Under the control of the controller100, the hydraulic control valve unit204controls the flow rate and direction of hydraulic fluid supplied to each of the right blade lift cylinder15, the left blade lift cylinder16, the drawbar shift cylinder17, the blade shift cylinder24, the power tilt cylinder25, and the circle rotation motor26.

In addition, the output signal of the joy stick32, the amount of sliding of the slide switch33, the output signal of the joy stick34, the amount of operation of an accelerator pedal35provided in the cab3, the output signal of a drawbar rotation angle meter36, a cylinder length meter37, and the like are input to the controller100. The accelerator pedal35is an input operation device of the operator and indicates output of the power source201. In addition, the drawbar rotation angle meter36measures (calculates) a drawbar rotation angle (α, β, γ) shown inFIG.2, and outputs the measured (calculated) result. The drawbar rotation angle meter36can consist of one or more sensors that measure the axis rotation angle (pivot angle) of the ball shaft23or the rotation angles at a plurality of locations of the drawbar12with respect to the main frame11, and a control unit that converts the measured value of the sensor into the drawbar rotation angle (α, β, γ), and the like. The cylinder length meter37measures (calculates) a cylinder length L1 of the right blade lift cylinder15, a cylinder length L2 of the left blade lift cylinder16, and a cylinder length L3 of the drawbar shift cylinder17, and outputs the measured (calculated) results. The cylinder length meter37can consist of sensors that measure cylinder lengths L1, L2 and L3, a control unit that converts the measured values of the plurality of sensors that detect the rotation angle of each cylinder into the cylinder length (L1, L2, L3), and the like.

<Operation Example of Control System>

FIG.6is a flowchart showing an operation example of the controller100shown inFIG.5. The processing shown inFIG.6is repeatedly executed in a predetermined cycle, for example, in a case where an input operation beyond the dead zone region is performed by the joy stick32.

When the processing shown inFIG.6is started, the controller100first acquires the posture (αj, βj, γj) of the joy stick32(step S101). Next, the controller100calculates the posture change (Δαj, Δβj, Δγj) of the joy stick32based on the posture (αj, βj, γj) one processing before (one cycle before) and the present posture (αj, βj, γj) (step S102). Next, the controller100acquires the drawbar rotation angle (α, β, γ) output by the drawbar rotation angle meter36and sets the drawbar rotation angle (α, β, γ) as the drawbar rotation angle initial value (α0, β0, γ0) (step S103).

Next, the controller100calculates a drawbar rotation angle target value (αt, βt, γt) based on the drawbar rotation angle initial value (α0, β0, γ0) and the posture change (Δαj, Δβj, Δγj) of the joy stick (step S104). The drawbar rotation angle target value (αt, βt, γt) is, for example, a value obtained by adding a value obtained by multiplying the posture change (Δαj, Δβj, Δγj) of the joy stick by a predetermined coefficient to the drawbar rotation angle initial value (α0, β0, γ0) for each component. The predetermined coefficient can be, for example, a value that can be adjusted by the operator within a certain range.

Next, the controller100acquires the drawbar rotation angle (α, β, γ) output by the drawbar rotation angle meter36and sets the drawbar rotation angle (α, β, γ) as the current drawbar rotation angle (αr, βr, γr) (step S105). Next, the controller100controls the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17based on the drawbar rotation angle target value (αt, βt, γ) and the current drawbar rotation angle (αr, βr, γr) (step S106). Next, the controller100determines whether the current drawbar rotation angle (αr, βr, γr) reaches the drawbar rotation angle target value (αt, βt, γt) (whether the current drawbar rotation angle (αr, βr, γr) is within the drawbar rotation angle target value (αt, βt, γt)) (step S107).

In a case where the current drawbar rotation angle (αr, βr, βr, γr) reaches the drawbar rotation angle target value (αt, βt, γt) (in case of “YES” in step S107), the controller100ends the processing shown inFIG.6. On the other hand, in a case where the current drawbar rotation angle (αr, βr, γr) does not reach the drawbar rotation angle target value (αt, βt, γt) (in case of “NO” in step S107), the controller100re-executes the processing from step S105onwards.

By the above processing, the controller100can change the rotation angle (α, β, γ) of the drawbar12to correspond to the operation input (change (Δαj, Δβj, Δγj) of the rotation angle (αj, βj, γj)) to the lever32L of the joy stick32. In this case, the drawbar12moves in the same direction as the lever rotation operation by the operator.

FIG.7is a system diagram showing an operation example of the control system300corresponding to the operation example shown inFIG.6. In the operation example shown inFIG.7, when the operation of the joy stick32is performed (S302) as the operator operation (S301), the joy stick signal conversion (S304) is performed in the controller100, and the posture change (Δαj, Δβj, Δβ) of the joy stick is calculated. In the controller100, the drawbar rotation angle target value (αt, βt, γt) is further calculated based on the posture change (Δαj, Δβj, Δγj) of the joy stick and the current drawbar rotation angle (α, β, γ) (S305).

In the controller100(S303), extension and retraction speeds ΔV1, ΔV2, and ΔV3of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17are further calculated based on (a deviation of) the current drawbar rotation angle (α, β, γ) and the drawbar rotation angle target value (αt, βt, γt) (S306).

Next, as the operation of the cylinder and work equipment (S308), the hydraulic valve control of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17is performed based on the extension and retraction speeds ΔV1, ΔV2, and ΔV3(S309). Here, the extension and retraction of the right blade lift cylinder (S310), the extension and retraction of the left blade lift cylinder (S311), and the extension and retraction of the drawbar shift cylinder (S312) are performed to rotate the drawbar12(S313). In addition, the current rotation angle is newly detected by the drawbar rotation angle meter36(S314).

The processing in the block S315is executed in a shorter cycle than the processing in the block S307.

By the above processing, the control system300can change the rotation angle (α, β, γ) of the drawbar12to correspond to the operation input (change (Δαj, Δβj, Δγj) of the rotation angle (αj, βj, γj)) to the lever32L of the joy stick32. In this case, the drawbar12moves in the same direction as the lever rotation operation by the operator.

Next, another operation example will be described with reference toFIG.8.FIG.8is a flowchart showing another operation example of the controller100shown inFIG.5. The processing shown inFIG.8is repeatedly executed in a predetermined cycle, for example, in a case where an input operation beyond the dead zone region is performed by the joy stick32.

When the processing shown inFIG.8is started, the controller100first acquires the posture (αj, βj, γj) of the joy stick32(step S201). Next, the controller100calculates the posture change (Δαj, Δβj, Δγj) of the joy stick32based on the posture one processing before (αj, βj, γj) and the current posture (αj, βj, γj) (step S202). Next, the controller100acquires the drawbar rotation angle (α, β, γ) output by the drawbar rotation angle meter36and sets the drawbar rotation angle (α, β, γ) as the drawbar rotation angle initial value (α0, β0, γ0) (step S203). The drawbar rotation angle initial value (α0, β0, γ0) may be calculated using the drawbar rotation angle (α, β, γ) calculated from the current length (L1, L2, L3) of each cylinder without using the drawbar rotation angle meter36. In this case, the calibration of the drawbar angle and the cylinder length is performed in advance.

Next, the controller100calculates the drawbar rotation angle target value (Δα, Δβ, Δγ) based on the drawbar rotation angle initial value (α0, β0, γ0) and the posture change (Δαj, Δβj, Δγj) of the joy stick (step S204). The drawbar rotation angle target value (αt, βt, γt) is, for example, a value based on the drawbar rotation angle initial value (α0, β0, γ0) and a value obtained by multiplying the posture change (Δαj, Δβj, Δγj) of the joy stick by a predetermined coefficient for each component. The predetermined coefficient can be, for example, a value that can be adjusted by the operator within a certain range.

Next, the controller100acquires the current length (L1, L2, L3) of each cylinder and sets the current length (L1, L2, L3) as the length initial value (L1o, L2o, L3o) of each cylinder (step S205). Next, the controller100calculates the target value (ΔL1, ΔL2, ΔL3) for the change in length of each cylinder based on the drawbar rotation angle initial value (α0, β0, γ0) and the drawbar rotation angle target value (Δα, Δβ, Δγ) (step S206).

In step S206, the controller100uses a rotation matrix and a coordinate transformation matrix to calculate the target value (ΔL1, ΔL2, ΔL3) for the change in length of each cylinder to correspond to the drawbar rotation angle target value (Δα, Δβ, Δγ). In the present embodiment, the mechanism of the drawbar12is classified into a model of a rotational three degrees of freedom parallel mechanism, in terms of machine kinematics. In the rotational three degrees of freedom parallel mechanism, there is one cylinder length (L1, L2, L3) for each of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17, which achieves the desired posture (α, β, γ) of the drawbar12. Therefore, when each cylinder length is adjusted at the same time, it is possible to control the posture (α, β, γ) of the drawbar12. That is, it is possible to calculate the amount of extension and retraction of the cylinder required for angular rotation from the three axes angles, which are lever input angle signals of the joy stick32. By using the rotation matrix, it is possible to calculate a change in the coordinates of a restraint point of each cylinder on the drawbar12. In addition, since the coordinates of the restraint point on the vehicle main body2side do not change, the length of each cylinder after the rotation of the drawbar12can be calculated.

Next, the controller100acquires the current length (L1, L2, L3) of each cylinder (step S207) and calculates the current length change (ΔL1r, ΔL2r, ΔL3r) of each cylinder (step S208). Next, the controller100controls the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17based on the target value (ΔL1, ΔL2, ΔL3) for the change in length of each cylinder and the current length change (ΔL1r, ΔL2r, ΔL3r) of each cylinder (step S209). Next, the controller100determines whether the current length change (ΔL1r, ΔL2r, ΔL3r) of each cylinder reaches the target value (ΔL1, ΔL2, ΔL3) for the change in the length of each cylinder (step S210).

In a case where the current length change (ΔL1r, ΔL2r, ΔL3r) of each cylinder reaches the target value (ΔL1, ΔL2, ΔL3) for the change in the length of each cylinder (in case of “YES” in step S210), the controller100ends the processing shown inFIG.8. On the other hand, in a case where the current length change (ΔL1r, ΔL2r, ΔL3r) of each cylinder does not reach the target value (ΔL1, ΔL2, ΔL3) for the change in the length of each cylinder (in case of “NO” in step S210), the controller100re-executes the processing from step S207onwards.

By the above processing, the controller100can change the rotation angle (α, β, γ) of the drawbar12to correspond to the operation input (change (Δαj, Δβj, Δγj) of the rotation angle (αj, βj, γj)) to the lever32L of the joy stick32. In this case, the drawbar12moves in the same direction as the lever rotation operation by the operator.

FIG.9is a system diagram showing an operation example of the control system300corresponding to the operation example shown inFIG.8. In the operation example shown inFIG.9, when the operation of the joy stick32is performed (8402) as the operator operation (S401), the joy stick signal conversion (S404) is performed in the controller100, and the posture change (Δαj, Δβj, Δγj) of the joy stick is calculated. In the controller100, the drawbar rotation angle target value (Δα, Δβ, Δγ) is further calculated based on the posture change (Δβj, Δβj, Δγj) of the joy stick and the current drawbar rotation angle (α, β, γ) (S405).

In the controller100(S403), the amounts of the extension and retraction ΔL1, ΔL2, and ΔL3 of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17are further calculated based on the current drawbar rotation angle (α, β, γ), the drawbar rotation angle target value (Δα, Δβ, Δγ), and the cylinder length (L1, L2, L3) (406).

Next, as the operation of the cylinder and work equipment (8408), the hydraulic valve control of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17is performed based on the amounts of the extension and retraction ΔL1, ΔL2, and ΔL3 (S409). Here, the extension and retraction of the right blade lift cylinder (8410), the extension and retraction of the left blade lift cylinder (8411), and the extension and retraction of the drawbar shift cylinder (8412) are performed to rotate the drawbar12(S413). In addition, the current rotation angle is newly detected by the drawbar rotation angle meter36(S414). In addition, the current cylinder length (L1, L2, L3) is newly detected by the cylinder length meter37(S415).

The processing in the block S416is executed in a shorter cycle than the processing in the block8407.

By the above processing, the control system300can change the rotation angle (α, β, γ) of the drawbar12to correspond to the operation input (change (Δαj, Δβj, Δγj) of the rotation angle (αj, βj, γj)) to the lever32L of the joy stick32. In this case, the drawbar12moves in the same direction as the lever rotation operation by the operator.

<Operation Example of Motor Grader>

Next, an operation example of the motor grader1will be described with reference toFIGS.10to17.FIGS.10to17are plan views and side views for describing an operation example of the motor grader according to one embodiment of the present invention.

FIG.10is a plan view showing the motor grader1in a traveling posture.FIG.11is a side view showing the motor grader1in a traveling posture. In a case of transitioning to the traveling posture, it is necessary to move the blade14upward. In this case, the operator performs a rotation operation around the axis in the left-right direction (rotation operation in a γj direction) with respect to the joy stick32shown inFIG.4, so that it is possible to lift the drawbar12without tilting the drawbar12around the front-rear axis (P direction inFIG.2). Therefore, the operation is easy to operate.

In a case where the traveling posture is set using the three operation levers that operate the cylinder lengths of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17, operations, which adjust a tilt by the drawbar shift cylinder17since the drawbar12tilts when the drawbar12is slightly lifted by the right blade lift cylinder15and the left blade lift cylinder16, and adjust a tilt by the drawbar shift cylinder17since the drawbar12tilts when the drawbar12is slightly lifted by the right blade lift cylinder15and the left blade lift cylinder16, need to be repeated multiple times.

FIG.12is a plan view showing the motor grader1in a trenching posture.FIG.13is a side view showing the motor grader1in a trenching posture. In a case of transitioning to the trenching posture, it is necessary to lower the right side of the drawbar12after moving the blade14upward. In this case, the operator first performs a rotation operation around the axis in the left-right direction (rotation operation in a γj direction) with respect to the joy stick32shown inFIG.4, so that it is possible to lift the drawbar12without tilting the drawbar12around the front-rear axis (β direction inFIG.2). Next, the operator performs a rotation operation (rotation operation in a βj direction) around the axis in the front-rear direction with respect to the joy stick32shown inFIG.4, so that it is possible to lower the right side of the drawbar12. In this case as well, the drawbar12can be lifted without tilting the drawbar12around the front-rear axis (β direction inFIG.2) during the rotation operation in the γj direction, so that the operation is easy to operate.

In a case where the trenching posture is set using the three operation levers that operate the cylinder lengths of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17, when lifting the drawbar12, operations, which adjust a tilt by the drawbar shift cylinder17since the drawbar12tilts when the drawbar12is slightly lifted by the right blade lift cylinder15and the left blade lift cylinder16, and adjust a tilt by the drawbar shift cylinder17since the drawbar12tilts when the drawbar12is slightly lifted by the right blade lift cylinder15and the left blade lift cylinder16, need to be repeated multiple times.

FIG.14is a plan view showing the motor grader1in a shoulder reach maximum (MAX) or minimum (MIN) posture.FIG.15is a side view showing the motor grader1in a shoulder reach maximum (MAX) or minimum (MIN) posture. In a case of transitioning to the shoulder reach maximum (MAX) or minimum (MIN) posture, it is necessary to lower the drawbar12without tilting the drawbar12around the front-rear axis, and at the same time, slide the drawbar12, for example, to the right side at the maximum extent. In this case, the operator first performs a rotation operation around the axis in the left-right direction (rotation operation in the γj direction) and a rotation operation around the axis in the up-down direction (rotation operation in the αj direction) with respect to the joy stick32shown inFIG.4, so that it is possible to lower the drawbar12without tilting the drawbar12around the front-rear axis (P direction inFIG.2), and at the same time, slide the drawbar12to the right side at the maximum extent. Further, by shifting the slide switch33, the blade14can be slid to the right.

In a case where achieving a shoulder reach maximum (MAX) using three operation levers that operate each cylinder length of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17, (1) first, the drawbar12is lifted to some extent by the right blade lift cylinder15and the left blade lift cylinder16(it is because the right side of the drawbar12is lowered by the operation (2)). (2) the drawbar shift cylinder17is used for maximum extension. (3) since the drawbar12tilts, the left side is lowered to adjust the drawbar12horizontal using the left blade lift cylinder16. (4) the blade14is installed on the ground and the height thereof is adjusted using the right blade lift cylinder15and the left blade lift cylinder16. (5) next, the blade14is slid to the right using the blade shift cylinder24. The operation is complicated as compared with the present embodiment.

FIG.16is a plan view showing the motor grader1in a ground leveling work posture.FIG.17is a side view showing the motor grader1in a ground leveling work posture. In the ground leveling work posture, it is necessary to finely adjust the height of the drawbar12while traveling. In this case, the operator visually inspects the ground leveling and checks the ground leveling depth by the visual inspection, so that the drawbar12can be lowered without tilting the drawbar12around the front-rear axis β direction ofFIG.2) by the rotation operation (rotation operation in the γj direction) around the axis in the left-right direction with respect to the joy stick32shown inFIG.4, and can immediately visually inspect the ground leveling again.

In a case where the ground leveling work posture is set by using the three operation levers that operate each cylinder length of the right blade lift cylinder15, the left blade lift cylinder16, and the drawbar shift cylinder17, (1) first, the operator checks the ground leveling depth by the visual inspection, (2) lowers the drawbar12in parallel using the right blade lift cylinder15and the left blade lift cylinder16, (3) lifts the left side using the left blade lift cylinder16to adjust the drawbar12to be parallel, for example, in a case where the left side is lowered too much, and (4) transitions to the visual inspection of the ground leveling. The operation is complicated as compared with the present embodiment.

Hitherto, the embodiment of the present invention has been described with reference to the drawings. However, a specific configuration is not limited to the above-described embodiment, and includes a design change within the scope not departing from the concept of the present invention. In addition, programs executed by a computer in the above-described embodiment can be partially or entirely distributed via a computer-readable recording medium or a communication line.

As described above, the controller100of the present embodiment is a control device that controls a drawbar attached to a main frame of a grader, in which a movement of the drawbar is generated by at least three actuators, and the control device controls, based on an output signal from one operation lever having at least three degrees of freedom, the plurality of actuators such that a movement of the one operation lever corresponds to the movement of the drawbar. The drawbar is restrained by the main frame and one ball shaft, and the axial rotation of the operation lever corresponds to the axial rotation of the drawbar about the ball shaft. Further, the operation lever includes an operation unit that operates a movement of a blade attached to the drawbar. In addition, in a case where the operation unit is slid left or right, the blade is slid left or right. In addition, the tilt of the operation lever corresponds to the tilt of the drawbar. In addition, the control system300of the present embodiment is an operation device including the control device and the operation lever. The motor grader1of the present embodiment is a work vehicle including a main frame, a drawbar attached to the main frame and restrained to the main frame by a ball shaft, three actuators attached to the main frame to determine a posture of the drawbar, one operation lever operated by an operator, and a control device that controls the actuators based on an output signal from the operation lever, in which the control device controls the actuators such that a movement of the operation lever corresponds to the movement of the drawbar.

According to each of these aspects, the operation can be simplified.

INDUSTRIAL APPLICABILITY

According to each aspect of the present invention, an operation can be simplified.

REFERENCE SIGNS LIST