JP7581137B2 - Work equipment - Google Patents

Description

The present invention relates to a work machine that rotates left and right by driving running devices provided on the left and right sides of the machine body.

2. Description of the Related Art Working machines that rotate left and right by driving traveling devices provided on the left and right sides of a machine body are known, such as those disclosed in Patent Documents 1 and 2, for example.
In the work machines disclosed in Patent Documents 1 and 2, left and right track-type traveling devices are driven in response to the operation of operating members such as a steering lever and a mode change switch, respectively, to turn the machine body left and right. In addition, by switching the drive speed and drive direction of the left and right traveling devices, the machine body can perform a number of types of turns with different turning radii.

JP 2004-74883 A Patent No. 3883484

Depending on the location where the work machine is working or traveling, it may be necessary to rotate the work machine with an extremely small turning radius. In this case, for example, of the left and right traveling devices, the traveling device on the outside of the turning center, which is located farther from the turning center, is driven in the opposite direction to the traveling device on the inside of the turning center, and the driving speed of the traveling device on the inside of the turning center is set to be lower than or equal to the driving speed of the traveling device on the outside of the turning center. As the driving speed of the traveling device on the inside of the turning center approaches the driving speed of the traveling device on the outside of the turning center, the turning radius of the work machine becomes smaller.

However, when the left and right travelling gears are driven in this way to turn the work machine with a very small turning radius, the friction between the travelling gear and the road surface increases, causing the machine to shake, and as the machine shakes, the friction between the travelling gear and the road surface is released, and this phenomenon is repeated. For this reason, if the machine is not in a stable state before turning, the shaking and vibration of the machine will be amplified while the work machine is turning with a very small turning radius, making the machine unstable and causing discomfort to the driver of the work machine or making the machine unable to be operated.

In view of the above problems, the present invention aims to provide a work machine that can improve turning stability and convenience.

The technical means of the present invention for solving the above technical problems is characterized by the following points.
A working machine according to one aspect of the present invention comprises a steering device including a first traveling device supporting a machine body on the left side of the machine body so that the machine body can travel, a second traveling device supporting the machine body on the right side of the machine body so that the machine body can travel, and an operating member for operating the traveling and steering of the machine body, the steering device driving the first traveling device and the second traveling device respectively in accordance with the operating state of the operating member to move the machine body in a straight line or turn, and a control device that determines whether the machine body is in a stable state, and when the operating member is operated to the maximum extent to the left or right and the control device determines that the machine body is in a stable state, the control device drives the first traveling device and the second traveling device in different directions at the same driving speed by the steering device, or drives the first traveling device and the second traveling device at a predetermined driving speed when the absolute value of the difference between the driving speed of the first traveling device and the driving speed of the second traveling device is determined to be a predetermined value. The first and second traveling devices are driven in different directions so that the turning radius is equal to or less than a certain threshold, thereby permitting a zero turn in which the vehicle turns with an extremely small turning radius close to zero, and if it is determined that the operating member is not operated to either the left or the right by the maximum amount or the vehicle is not in a stable state, the zero turn is prohibited, and if it is determined that the operating member is operated to either the left or the right by the maximum amount and the vehicle is not in a stable state, the steering device drives the outside traveling device of the first and second traveling devices that is located farther from the turning center of the vehicle based on the operation state of the operating member, and the steering device drives the inside traveling device that is closer to the turning center of the vehicle at a driving speed slower than the driving speed of the outside traveling device and in the driving direction opposite to that of the outside traveling device .

In one aspect of the present invention, the work machine is equipped with an operation detection unit that detects the operation state of the operating member, and the steering device transmits power output from a prime mover provided on the machine body to at least one of the first traveling device and the second traveling device depending on the operation state of the operating member to drive the traveling device, and when the control device permits the zero turn, it controls the steering device based on the operation state of the operating member to perform the zero turn.

In one aspect of the present invention, when the operating member is operated to the left or right by an amount less than the maximum amount, the control device drives the outer running device of the first and second running devices that is located farther from the turning center of the machine body using the steering device based on the operating state of the operating member, and drives the inner running device that is located closer to the turning center of the machine body using the steering device at a driving speed that is slower than the driving speed of the outer running device by a predetermined ratio in a driving direction opposite to that of the outer running device.

In one aspect of the present invention, the steering device drives at least one of the first and second traveling devices so that the drive speed of the inside traveling device located closer to the turning center of the vehicle is zero or slower than the drive speed of the outside traveling device located farther from the turning center of the vehicle, and a mode selection unit is provided that can select one of the turn modes: a first turn mode in which another turn can be performed in which the vehicle turns with a turning radius larger than the turning radius in the zero turn, and a second turn mode in which the zero turn can be performed. When the first turn mode is selected by the mode selection unit, the control device controls the steering device based on the operation state of the operating member to perform the other turn, and when the second turn mode is selected by the mode selection unit, the operating member is operated to the maximum extent to the left or right, and it is determined that the vehicle is in a stable state, the control device permits the zero turn and controls the steering device based on the operation state of the operating member to perform the zero turn.

In addition, in one aspect of the present invention, when the first turn mode is selected by the mode selection unit, the control device controls the steering device based on the operation state of the operating member to perform the other turn.
In addition, in one aspect of the present invention, the mode selection unit can select, as the first turn mode, a super-pivot turn mode in which a super-pivot turn of the aircraft can be performed, a pivot turn mode in which a pivot turn of the aircraft can be performed, or a gentle turn mode in which a gentle turn of the aircraft can be performed.

In one aspect of the present invention, the work machine is equipped with a speed detection unit that detects the speed of the machine, and the control device determines that the machine is in a stable state if the speed of the machine is equal to or less than a predetermined speed, and determines that the machine is not in a stable state if the speed of the machine is faster than the predetermined speed.
Furthermore, in one aspect of the present invention, the first traveling device and the second traveling device are each composed of a track-type traveling device, the steering device includes a continuously variable transmission that continuously changes the drive speed of the first traveling device and the drive speed of the second traveling device, and the control device changes the drive speed and drive direction of the first traveling device and the second traveling device, respectively, by controlling the speed change of the continuously variable transmission.

The present invention makes it possible to provide a work machine with improved turning stability and convenience.

FIG. 2 is a diagram showing a power transmission structure provided in the working machine. FIG. 2 is a control block diagram of a traveling system of the work machine. FIG. 4 is a characteristic diagram of a turn mode executed by the work machine. 4 is a flowchart showing a swing operation of the work machine. 5 is a flowchart showing details of the zero-turn mode process of FIG. 4. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 6 is a side view of the work machine 100.
In this embodiment, the working machine 100 is a head-propelling combine harvester. Note that the working machine according to the present invention is not limited to a combine harvester, and may be configured as another working machine such as a tractor, a track loader, or a backhoe.

As shown in Fig. 6, the work machine 100 includes a machine body 2 and a traveling device 1 that supports the machine body 2 so that it can travel. The traveling device 1 is made up of a first traveling device 1L of a track type provided below the left side of the machine body 2, and a second traveling device 1R of a track type provided below the right side of the machine body 2 (see Fig. 1). The first traveling device 1L and the second traveling device 1R support the machine body 2 so that it can travel.
The mowing work device 3 is connected to the front of the machine body 2 so that it can be raised and lowered. The mowing work device 3 is a mowing work device designed for multiple-row mowing. A driver's seat 4 for a driver to sit on is provided at the right front of the machine body 2. A control platform 6 is provided between the driver's seat 4 and the mowing work device 3. The control platform 6 is provided with a plurality of operating members (reference numbers omitted in FIG. 6 ) that can be operated by the driver seated in the driver's seat 4.

A prime mover 5 that is a drive source for the working machine 100 is provided inside the machine body 2. The prime mover 5 is composed of an engine. As another example, another prime mover such as an electric motor may be used. A threshing device 7 is mounted on the left rear part of the machine body 2. A grain recovery tank 9 including a screw-type unloader 8 is mounted on the right side of the threshing device 7.
The harvesting work apparatus 3 includes a lifting device 11, a clipper-type harvester 12, a frame 13, and a stump transport device (not shown). The frame 13 is supported on the front of the machine body 2 so as to be able to swing up and down. The stump transport device transports the harvested stumps toward a feed chain (not shown) of the threshing device 7. A hydraulic cylinder 15 is provided on the bottom of the machine body 2. The hydraulic cylinder 15 raises and lowers the entire harvesting work apparatus 3.

FIG. 1 is a diagram showing a power transmission structure provided in a working machine 100. As shown in FIG.
One side of the transmission case 20 shown in Fig. 1 is provided with hydraulic continuously variable transmissions (HST) 21, 22, 23. The first continuously variable transmission 21 drives the first traveling device 1L, the second continuously variable transmission 22 drives the second traveling device 1R, and the third continuously variable transmission 23 drives the harvesting implement 3. In other words, the continuously variable transmissions 21 and 22 are transmissions for traveling, and the continuously variable transmission 23 is a transmission for work. Note that, for convenience, in Fig. 1, the first traveling device 1L is shown to the right of the second traveling device 1R.

Each of the continuously variable transmissions 21, 22, 23 has an axial plunger type variable displacement hydraulic pump (hereinafter referred to as a "variable displacement pump") P1, P2, P3, a fixed displacement hydraulic motor (hereinafter referred to as a "constant displacement motor") M1, M2, M3, a port block 21c, 22c, 23c for hydraulic control, and the like.
An input shaft 24 is provided approximately in the center of the transmission case 20. Power from the prime mover 5 is transmitted via a belt to one end of the input shaft 24 protruding from the transmission case 20 on the opposite side to the continuously variable transmissions 21-23.

The power input from the prime mover 5 to the input shaft 24 via the belt is transmitted from the counter gear G1 to the gears G2 and G3 to the pump shafts 21a and 22a of the continuously variable transmissions 21 and 22. The power input from the prime mover 5 to the input shaft 24 is also transmitted from the counter gear G1 to the gear G4 to the pump shaft 23a of the continuously variable transmission 23. In other words, the variable displacement pumps P1, P2, and P3 are driven by the power of the prime mover 5.

By changing the angle of the swash plate of each of the variable displacement pumps P1, P2, P3, it is possible to change the discharge direction and discharge amount of hydraulic oil from the variable displacement pumps P1, P2, P3. The corresponding constant displacement motors M1, M2, M3 are rotated by the hydraulic oil discharged from the variable displacement pumps P1, P2, P3. By changing the discharge direction and discharge amount of hydraulic oil from the variable displacement pumps P1, P2, P3, it is possible to change the discharge direction and discharge amount of hydraulic oil from the corresponding constant displacement motors M1, M
2. It is possible to change the rotation direction of the motor shafts 21b, 22b, and 23b of M3 and to change the speed continuously from a speed of 0 (zero).

The speed change output from the motor shaft 21b of the first variable speed device 21 is transmitted to the gear-type first auxiliary speed change mechanism 25, the first intermediate shaft 26, the second intermediate shaft 27, the gear reduction mechanism 28, and the axle 29, and the axle 29 rotates to drive the first traveling device 1L. The speed change output from the motor shaft 22b of the second variable speed device 22 is transmitted to the gear-type second auxiliary speed change mechanism 30, the first intermediate shaft 31, the second intermediate shaft 27, the gear reduction mechanism 32, and the axle 33, and the axle 33 rotates to drive the second traveling device 1R. The steering device 10 including these mechanical parts 21, 22, 24-33, 1L, and 1R is provided in the work machine 100.

Each of the sub-transmission mechanisms 25, 30 is configured to be capable of shifting between two speed stages, a low speed stage and a high speed stage, from a neutral state. The power whose speed has been changed by the first continuously variable transmission device 21 is switched to two speed stages, a high speed stage and a low speed stage, by the first sub-transmission mechanism 25. The power whose speed has been changed by the second continuously variable transmission device 22 is switched to two speed stages, a high speed stage and a low speed stage, by the second sub-transmission mechanism.
The gear reduction mechanisms 28, 32 are loosely fitted and supported on the second intermediate shaft 27. The first intermediate shaft 26 is supported on the left and right side walls of the transmission case 20, and the first intermediate shaft 31 is loosely fitted and supported on the first intermediate shaft 26. A hydraulically operated multi-plate linear clutch 34 is provided between the first intermediate shaft 26 and the first intermediate shaft 31. The linear clutch 34 is engaged and disengaged by the hydraulic pressure of the working oil.

When the vehicle 2 travels straight, the first and second variable speed transmissions 21 and 22 are driven in the same drive state (the angle of the swash plates of the variable displacement pumps P1 and P2, the discharge volume of the variable displacement pumps P1 and P2, and the rotation direction and rotation speed of the fixed displacement motors M1 and M2 are the same or approximately the same), and the straight-travel clutch 34 is engaged (connected). As a result, the first intermediate shaft 26 and the first intermediate shaft 31 are integrated, the axles 29 and 33 rotate in the same direction at the same speed, and the left and right traveling devices 1L and 1R also rotate in the same direction at the same speed, causing the vehicle 2 to travel straight.

When turning the vehicle body 2 left or right, the straight-line clutch 34 is disengaged (disconnected), and the first and second variable speed devices 21 and 22 are driven in different driving states, or at least one of the first and second variable speed devices 21 and 22 is driven.
An inwardly expanding brake 35 is attached to the first intermediate shaft 26. For example, when the work machine 100 (machine body 2) is parked, the prime mover 5 is stopped and the brake 35 is applied.

When the linear clutch 34 is not being engaged or switched, there is no pressure in the oil passage (not shown) that supplies hydraulic oil to the linear clutch 34. At this time, a spring provided inside the linear clutch 34 elastically presses a friction plate (not shown), causing the linear clutch 34 to be in a lightly connected state. For this reason, when the brake 35 is applied while the linear clutch 34 is not being engaged or switched, the braking action is exerted not only on the first intermediate shaft 26 but also on the first intermediate shaft 31, and the first traveling device 1L and the second traveling device 1R are braked.

The speed change output from the motor shaft 23b of the third continuously variable transmission 23 is transmitted to the mowing implement 3 via gears G12, G13, the PTO shaft 36, a mowing clutch (not shown), a belt (not shown), and the like. In this way, the mowing implement 3 is driven.
FIG. 2 is a control block diagram of a traveling system of the work machine 100.
In addition, the working machine 100 also has an electrical configuration for the work system to control the harvesting work device 3 and the threshing work device 7, etc., but since this configuration is similar to a known configuration, it will not be illustrated or described in this embodiment.

The work machine 100 is equipped with a control device 50. The control device 50 is configured with an electronic control unit (ECU) including a CPU, memory, etc. Configurations other than the control device 50 and the detectors 62 to 65 shown in FIG. 2 are included in the steering device 10.
The work machine 100 and the steering device 10 are provided with, as operation members, a main speed change lever 37, an auxiliary speed change lever 38, a steering lever 39, a mode selection switch (mode selection section) 40, and an accelerator lever 41. These operation members 37 to 41 are installed on the operation console 6 (FIG. 6) or the like.

The main speed change lever 37 can be swung forward from a neutral position in the forward direction or backward in the reverse direction. The main speed change lever 37 is biased by an elastic member such as a spring so that it remains stationary in the neutral position when not operated. The operation state of the main speed change lever 37 (whether or not it is operated, the direction of operation, and the amount of operation) is detected by a potentiometer 42.
The sub-speed change lever 38 can be swung forward from a neutral position in the high-speed direction or backward in the low-speed direction. The sub-speed change lever 38 is biased by an elastic member such as a spring so that it remains stationary in the neutral position when not operated. The operation state of the sub-speed change lever 38 (whether it is operated and the direction of operation) is detected by a switch mechanism 43. The switch mechanism 43 has, for example, a plurality of electrical fixed contacts and movable contacts, and the movable contacts move according to the operation state of the sub-speed change lever 38, switching the contact state between the movable contacts and the fixed contacts, so that an electrical signal according to the contact state is output from the switch mechanism 43.

The steering lever 39 can be swung from a straight-ahead position, which is a neutral position, to the left for a left turn direction and to the right for a right turn direction. The steering lever 39 is biased by an elastic member such as a spring so that it remains stationary in the straight-ahead position when not operated. The operation state of the steering lever 39 (whether or not it is operated, the direction of operation, and the amount of operation) is detected by a potentiometer 44.
The mode selection switch 40 is a switch that is operated to select a turn mode for turning the work machine 100. An operation knob (reference number omitted) of the mode selection switch 40 can be switched to four positions by being swung. The switching position of the mode selection switch 40 is detected by a switch mechanism 45. The configuration of the switch mechanism 45 is similar to that of the switch mechanism 43, except for, for example, the number of fixed contacts.

The gentle turn mode can be selected by switching the mode selection switch 40 to the first position P1. The swivel mode can be selected by switching the mode selection switch 40 to the second position P2. The super swivel mode can be selected by switching the mode selection switch 40 to the third position P3. The zero turn mode can be selected by switching the mode selection switch 40 to the fourth position P4.

By executing the four turn modes of gentle turn mode, pivot turn mode, super pivot turn mode, and zero turn mode in the work machine 100, at least one of the first traveling device 1L and the second traveling device 1R is driven and the machine body 2 turns. The turning radius of the machine body 2 decreases in the order of gentle turn mode, pivot turn mode, super pivot turn mode, and zero turn mode. When the zero turn mode is executed in the work machine 100, the machine body 2 turns with an extremely small turning radius that is close to zero (including zero). The zero turn mode is also called the extremely small turning mode or the high-speed spin turning mode.

The accelerator lever 41 can be swung in an accelerating direction from the home position forward, and in a returning direction (opposite to the accelerating direction) to the home position. The accelerator lever 41 is biased by an elastic member such as a spring so that it remains stationary at the home position when not operated. The operation state of the accelerator lever 41 (whether it is operated and the amount of operation) is detected by a potentiometer 46.

The control device 50 detects the operating states of the main shift lever 37 , the sub shift lever 38 , the steering lever 39 , the mode selection switch 40 and the accelerator lever 41 based on the electrical signals output from the potentiometers 42 , 44 , 46 and the switch mechanisms 43 , 45 .
The first valve unit 51 and the first servo cylinder 55 are components for controlling the speed change state of the first variable speed device 21 corresponding to the first traveling device 1L. The second valve unit 52 and the second servo cylinder 58 are components for controlling the speed change state of the continuously variable speed device 22 corresponding to the second traveling device 1R. Each of the valve units 51, 52 includes a pair of normally closed electromagnetic on-off valves (not shown) and a pair of normally open electromagnetic on-off valves (not shown).

The first servo cylinder 55 is operated by the hydraulic pressure of the hydraulic oil supplied from the first valve unit 51 to change the angle of a swash plate of the variable displacement pump P1 included in the first continuously variable transmission 21. The second servo cylinder 58 is operated by the hydraulic pressure of the hydraulic oil supplied from the second valve unit 52 to change the angle of a swash plate of the variable displacement pump P2 included in the second continuously variable transmission 22. The angle of the swash plate of the variable displacement pump P1 is detected by a potentiometer 56.
The angle of the swash plate of the variable displacement pump P2 is detected by a potentiometer 59. The configurations of the valve units 51, 52 and the servo cylinders 55, 58 are similar to those of known valve units and servo cylinders, for example, as disclosed in Cited Document 1.

The constant displacement motor M1 is driven to rotate by hydraulic oil discharged from the variable displacement pump P1. The constant displacement motor M2 is driven to rotate by hydraulic oil discharged from the variable displacement pump P2. The rotation speed and direction of the constant displacement motor M1 are detected by a rotation detection unit 57. The rotation speed and direction of the constant displacement motor M2 are detected by a rotation detection unit 60. The configuration of the continuously variable transmissions 21 and 22 including these pumps P1 and P2 and motors M1 and M2 is similar to the configuration of a known continuously variable transmission, for example as disclosed in Reference 1.

The third valve unit 53 and the sub-speed cylinder 61 are configured to control the shift state of the sub-transmission mechanisms 25, 30. The third valve unit 53 includes a pair of electromagnetic on-off valves (not shown). The sub-speed cylinder 61 is operated by the hydraulic pressure of the hydraulic oil supplied from the third valve unit 53, and switches the sub-transmission mechanisms 25, 30 to a high speed stage, a low speed stage, or a neutral state via a shift shaft (not shown). The configuration of the third valve unit 53 and the sub-speed cylinder 61 is similar to the configuration of a known valve unit and a shift operation cylinder, for example, as disclosed in Reference 1.

The control device 50 controls the opening/closing state of the electromagnetic opening/closing valve of the third valve unit 53 based on the operating state (operating position and operating direction) of the sub-transmission lever 38 detected by the switch mechanism 43, thereby actuating the sub-transmission cylinder 61 and switching the shifting state of the sub-transmission mechanisms 25, 30.
The fourth valve unit 54 is configured to control the on/off state of the linear clutch 34. The fourth valve unit 54 includes a pair of electromagnetic on-off valves (not shown). The linear clutch 34 is turned on (connected), turned off (disconnected), or switched to a neutral state by the hydraulic pressure of the hydraulic oil supplied from the fourth valve unit 54. The configurations of the fourth valve unit 54 and the linear clutch 34 are similar to those of a known valve unit and linear clutch, for example, as disclosed in Cited Document 1.

The control device 50 switches the straight-ahead clutch 34 between an engaged state, disengaged state, or neutral state by controlling the open/close state of the electromagnetic on-off valve of the fourth valve unit 54 based on the operating state (operation direction and amount) of the steering lever 39 detected by the potentiometer 44.
In addition, the control device 50 feedback controls the opening and closing states of the electromagnetic on-off valves of the valve units 51, 52 based on the operation state (operation direction and operation amount) of the main shift lever 37 detected by the potentiometer 42, the operation state (operation direction and operation amount) of the steering lever 39 detected by the potentiometer 44, the operation state (operation position and operation direction) of the sub-shift lever 38 detected by the switch mechanism 43, and the angles of the swash plates of the variable displacement pumps P1, P2 detected by the potentiometers 56, 59.

This causes the servo cylinders 55, 58 to operate, changing the angle of the swash plates of the variable displacement pumps P1, P2 of the continuously variable transmissions 21, 22. The discharge direction and discharge amount of the hydraulic oil discharged from the variable displacement pumps P1, P2 are also changed accordingly, and the drive state (rotation direction and rotation speed) of the constant displacement motors M1, M2 is also changed. In other words, the control device 50 changes the speed of the continuously variable transmissions 21, 22 based on the operating state of the main shift lever 37, the sub shift lever 38, the steering lever 39, the mode selection switch 40, etc. (which may include the accelerator lever 41).

Specifically, for example, with the steering lever 39 in the neutral position, the main shift lever 71 is swung from the neutral position in the forward or reverse direction, and the sub-shift lever 38 is swung from the neutral position in the high-speed or low-speed direction. In this case, the control device 50 determines the same value as the target shift position (target angle of the swash plate of the variable displacement pumps P1, P2) of the continuously variable transmissions 21, 22 based on the operation direction and operation amount of the main shift lever 71 and the operation position of the sub-shift lever 38. Then, the control device 50 operates the servo cylinders 53, 54 by feedback controlling the valve units 51, 52 as described above, changes the angle of the swash plate of the variable displacement pumps P1, P2, matches the angle of the swash plate with the target shift position (target angle), and maintains the matched state.

As described above, the constant displacement motors M1 and M2 rotate in the same direction at the same speed in response to the operation of the accelerator lever 41, and the continuously variable transmissions 21 and 22 change speed for forward or reverse. The first traveling device 1L and the second traveling device 1R also drive in the same direction at the same speed, and the vehicle 2 moves forward or backward without turning. The control device 50 controls the drive of the prime mover 5 based on the operating state (operation direction and amount) of the accelerator lever 41 detected by the potentiometer 46.

Also, for example, while the vehicle 2 is moving forward or backward, the steering lever 39 is swung from the neutral position in a left turning direction (or a right turning direction). In this case, the control device 50 corrects the target shift position of the first continuously variable transmission 21 (or the second continuously variable transmission 22) corresponding to the operation direction of the steering lever 39 based on the operation amount of the steering lever 39.
In detail, as the amount of operation of the steering lever 39 increases, the control device 50 corrects the target shift position of the variable displacement pump P1 of the first continuously variable transmission 21 (or the variable displacement pump P2 of the second continuously variable transmission 22) in a direction that decelerates the rotational speed of the constant displacement motor M1 of the first continuously variable transmission 21 (or the constant displacement motor M2 of the second continuously variable transmission 22) corresponding to the operation direction of the steering lever 39.

The control device 50 then operates the servo cylinders 55, 58 by feedback controlling the valve units 51, 52 as described above, so as to match the angle of the swash plate of the variable displacement pump P1 of the first continuously variable transmission 21 with the corrected target shift position and maintain this matched state, and also maintains the angle of the swash plate of the variable displacement pump P2 of the second continuously variable transmission 22 in a state where it matches the target shift position. As a result, the drive speed of the constant displacement motor M1 is decelerated to become slower than the drive speed of the constant displacement motor M2, and the continuously variable transmissions 21, 22 are shifted for left turning. Also, the drive speed of the first traveling device 1L is decelerated to become slower than the drive speed of the second traveling device 1R, and the vehicle 2 turns left.

The speed detection unit 62 detects the speed of the machine body 2 and the drive speed of the traveling device 1 (1L, 1R). The tilt detection unit 63 is made up of a gyro sensor and the like, and detects the tilt angle and attitude of the machine body 2. The lifting position detection unit 64 detects the lifting height of the harvesting work device 3 (Figure 6). The object detection unit 65 is made up of a LIDAR, ultrasonic sensor, or imaging device (camera), and detects objects around the machine body 2. Examples of objects include the road surface, structures, people, and obstacles. The control device 50 determines whether the machine body 2 is in a stable state based on the detection results of at least one of the detection units 62 to 65, 57, and 60.

FIG. 3 is a characteristic diagram of the turn mode executed by the work machine 100. As shown in FIG.
In the characteristic diagram of Fig. 3, the horizontal axis indicates the amount of operation of the steering lever 39, and the vertical axis indicates the ratio (inside/outside speed ratio) of the drive speed (output rotation speed) of the travelling device on the inside of the turning position located closer to the turning center to the drive speed (output rotation speed) of the travelling device on the outside of the turning position located farther from the turning center when the vehicle 2 turns, among the left and right travelling devices 1L, 1R. The control data (table data or function data) representing each of the lines L1 to L4 shown in Fig. 3 are stored in advance in the internal memory of the control device 50.

When the steering lever 39 is swung in the left or right turning direction and the accelerator lever 41 is swung in the acceleration direction so that the work machine 100 (machine body 2) turns left or right, of the left and right traveling devices 1L, 1R, the traveling device on the inside of the turn is decelerated by the steering device 10 relative to the traveling device on the outside of the turn.
When the mode selection switch 40 (FIG. 2) is operated to select any one of the turn modes, namely, the gentle turn mode, the yaw turn mode, the ultra-yaw turn mode, and the zero turn mode, the control device 50 executes the selected turn mode.

When the steering lever 39 is swung in the left or right turning direction while any of the turn modes is being executed, the control device 50 detects the operation direction and amount of the steering lever 39, the operation direction and amount of the main shift lever 37, and the operation position of the sub shift lever 38 by means of the potentiometers 42, 44 and the switch mechanism 43. In addition, when the accelerator lever 41 is swung in the acceleration direction, the control device 50 detects the operation amount of the accelerator lever 41.

Then, based on the detected operating states of the operating members 37 to 40, the control device 50 determines the drive direction and drive speed of the traveling device on the outside of the turn that does not correspond to the operating direction of the steering lever 39 (the traveling device located in the opposite direction to the operating direction of the steering lever 39), and the target shift position of the continuously variable transmission (either the first continuously variable transmission 21 or the second continuously variable transmission 22) that corresponds to that traveling device.

Next, the control device 50 determines the inside/outside speed ratio between the drive speed Vi of the traveling device on the inside of the turn (the traveling device located in the operation direction of the steering lever 39) and the drive speed Vo of the traveling device on the outside of the turn based on the turning mode being executed, the operation amount of the steering lever 39, and the control data of lines L1 to L4 in Figure 3 (inside/outside speed ratio = Vi/Vo). The control device 50 then multiplies the drive speed of the traveling device on the outside of the turn by the determined inside/outside speed ratio to determine the drive speed and drive direction of the traveling device on the inside of the turn.

For example, when the gentle turning mode is being executed, the control device 50 determines the inside/outside speed ratio based on the operation amount of the steering lever 39 and the control data of line L1 in FIG. 3. As shown by line L1, in the gentle turning mode, as the operation amount of the steering lever 39 increases, the inside/outside speed ratio decreases, and when the steering lever 39 is operated to the maximum amount (operation amount MAX), the inside/outside speed ratio becomes 0.3 (L1 in FIG. 3). That is, in the gentle turning mode, the inside/outside speed ratio becomes a value equal to or greater than 0.3 and smaller than 1. Also, the drive speed Vi of the traveling device on the inside of the turn is decelerated to a value equal to or greater than 0.3 times the drive speed Vo of the traveling device on the outside of the turn and smaller than the drive speed Vo (specifically, 1 times the drive speed Vo) (0.3Vo≦Vi<Vo).

When the pivot turn mode is being executed, the control device 50 determines the inside/outside speed ratio based on the amount of operation of the steering lever 39 and the control data of line L2 in FIG. 3. As shown by line L2, in the pivot turn mode, the inside/outside speed ratio decreases as the amount of operation of the steering lever 39 increases, and when the steering lever 39 is operated to the maximum amount, the inside/outside speed ratio becomes 0 (L2 in FIG. 3). That is, in the pivot turn mode, the inside/outside speed ratio becomes a value greater than or equal to 0 and smaller than 1. Also, the drive speed Vi of the traveling device on the inside of the turn is decelerated to a value greater than or equal to 0 and smaller than the drive speed Vo of the traveling device on the outside of the turn (0≦Vi<Vo). When the drive speed of the traveling device on the inside of the turn is 0, the traveling device is in a stopped state.

When the whirlpool turning mode is being executed, the control device 50 determines the inside/outside speed ratio based on the amount of operation of the steering lever 39 and the control data of line L3 in FIG. 3. As shown by line L3, in the whirlpool turning mode, the inside/outside speed ratio decreases as the amount of operation of the steering lever 39 increases, and when the steering lever 39 is operated to the maximum extent, the inside/outside speed ratio becomes -0.3 (L3 in FIG. 3). That is, in the whirlpool turning mode, the inside/outside speed ratio becomes -0.3 or more and less than 1. Also, the drive speed Vi of the traveling device on the inside of the turn is decelerated to a value that is -0.3 times or more the drive speed Vo of the traveling device on the outside of the turn and less than the drive speed Vo (-0.3Vo≦Vi<Vo). Note that when the inside/outside speed ratio is determined to be a negative value, the traveling device on the inside of the turn is driven in the opposite direction to the traveling device on the outside of the turn (reverse drive).

When the zero-turn mode is being executed, the control device 50 determines the inside/outside speed ratio based on the amount of operation of the steering lever 39 and the control data of line L4 in FIG. 3. As shown by line L4, in the zero-turn mode, the inside/outside speed ratio decreases as the amount of operation of the steering lever 39 increases, and when the steering lever 39 is operated to the maximum amount, the inside/outside speed ratio becomes -1 (L4 in FIG. 3). That is, in the zero-turn mode, the inside/outside speed ratio becomes a value that is -1 or more and less than 1. Also, the drive speed Vi of the traveling device on the inside of the turn is decelerated to a value that is -1 or more times the drive speed Vo of the traveling device on the outside of the turn and less than the drive speed Vo (-Vo≦Vi<Vo).

As described above, when the control device 50 determines the drive speed and drive direction of the traveling devices 1L and 1R, it determines the target shift positions of the continuously variable transmissions 21 and 22 corresponding to the traveling devices 1L and 1R, respectively, based on pre-stored calculation data (control data such as calculation formulas or tables). Then, the control device 50 feedback-controls the valve units 51 and 52 as described above to operate the servo cylinders 55 and 58, changes the angles of the swash plates of the variable displacement pumps P1 and P2, and matches the angles of the swash plates with the corresponding target shift positions, and maintains the matched state. As a result, hydraulic oil is discharged from the variable displacement pumps P1 and P2 at a flow rate and pressure according to the target shift positions, and the hydraulic oil is supplied to the constant displacement motors M1 and M2.

For example, when the gentle turning mode is being executed, the constant displacement motors M1 and M2 are driven in the same direction at different speeds. Also, of the left and right traveling devices 1L and 1R, the traveling device on the inside of the turn is driven in the same direction as the traveling device on the outside of the turn at a slower drive speed than the traveling device on the outside of the turn. As a result, the machine body 2 makes a gentle turn to the left or right.
In addition, when the pivot turn mode is being executed, the constant displacement motors M1 and M2 are driven in the same direction at different speeds, or one of the constant displacement motors corresponding to the inside traveling unit is stopped. In addition, the left and right traveling units 1L and 1R are driven in the same direction at different speeds, or the inside traveling unit is stopped.

At this time, if the amount of operation of the steering lever 39 is maximum, the control device 50 determines the inside/outside speed ratio to 0, and determines the drive speed of the traveling device on the inside of the turn to 0. As described above, the control device 50 determines the drive direction of the traveling device on the outside of the turn according to the operation direction of the steering lever 39, and determines the drive speed of the traveling device on the outside of the turn according to the operation amount of the steering lever 39 and the operation amount of the accelerator lever 41, etc. Furthermore, the control device 50 determines the target shift positions of the continuously variable transmissions 21 and 22, respectively, and performs gear shifting of the continuously variable transmissions 21 and 22.

As a result, the traveling device on the outside of the turn drives in a direction and at a speed according to the operation direction of the steering lever 39 and the operation amount of the levers 39, 41, while the traveling device on the inside of the turn stops. In addition, one of the constant displacement motors M1, M2 corresponding to the traveling device on the outside of the turn drives in a direction and at a speed according to the operation direction of the steering lever 39 and the operation amount of the levers 39, 41, while the other constant displacement motor corresponding to the traveling device on the inside of the turn stops. As a result, the machine body 2 makes a pivot turn to the left or right.

Even if the pivot turn mode is being executed, if the operation amount of the steering lever 39 is not the maximum amount and the operation amount is not 0, the control device 50 determines the inside/outside speed ratio of the left and right traveling devices 1L, 1R to a positive value greater than 0 and less than 1. As described above, the control device 50 determines the driving direction and driving speed of the traveling device on the inside of the turn and the traveling device on the outside of the turn, respectively, determines the target speed change positions of the continuously variable transmissions 21, 22, respectively, and changes the speed of the continuously variable transmissions 21, 22. As a result, the constant displacement motors M1, M2 are driven at different speeds in the same direction, and the left and right traveling devices 1L, 1R are also driven at different speeds in the same direction, and the vehicle 2 makes a quasi-pivot turn to the left or right. A quasi-pivot turn is a turn in which the turning radius of the vehicle 2 is greater than that of a gentle turn and smaller than that of a pivot turn.

When the vehicle is in the pivot turn mode, the constant displacement motors M1 and M2 are driven in different directions at different speeds, and the left and right traveling devices 1L and 1R are also driven in different directions at different speeds.
At this time, if the amount of operation of the steering lever 39 is relatively large, the control device 50 determines the inside/outside speed ratio to be less than 0 and a negative value equal to or greater than −0.3, based on the amount of operation of the steering lever 39. In addition, as described above, the control device 50 determines the drive directions and drive speeds of the traveling device on the outside of the turn and the traveling device on the inside of the turn, and determines the target shift positions of the continuously variable transmissions 21, 22, and changes the speed of the continuously variable transmissions 21, 22.

As a result, the traveling device on the outside of the turn drives in a direction according to the operation direction of the steering lever 39, while the traveling device on the inside of the turn drives in the opposite direction to the traveling device on the outside at a slower drive speed than the traveling device on the outside of the turn. Also, of the constant displacement motors M1, M2, one of the constant displacement motors corresponding to the traveling device on the outside of the turn drives in a direction according to the operation direction of the steering lever 39, while the other constant displacement motor corresponding to the traveling device on the inside of the turn drives in the opposite direction to the one constant displacement motor at a slower drive speed than the one constant displacement motor. This causes the vehicle 2 to make a pivot turn to the left or right.

Incidentally, even when the pivot turn mode is being executed, if the amount of operation of the steering lever 39 is small and not 0, the control device 50 sets the inside/outside speed ratio to a positive value greater than or equal to 0 and less than 1. As described above, the control device 50 determines the drive directions and drive speeds of the traveling device on the inside of the turn and the traveling device on the outside of the turn, respectively, and determines the target shift positions of the continuously variable transmissions 21, 22, respectively, and changes the speed of the continuously variable transmissions 21, 22.

As a result, the constant displacement motors M1, M2 are driven in the same direction at different speeds, or one of the constant displacement motors M1, M2 is stopped. The left and right traveling devices 1L, 1R are also driven in the same direction at different speeds, or one of the left and right traveling devices 1L, 1R is stopped. As a result, the machine body 2 makes a gentle turn to the left or right, a quasi-pivot turn, or a pivot turn.
During the zero-turn mode, the constant displacement motors M1 and M2 are driven in different directions at different speeds or at the same speed, and the left and right traveling devices 1L and 1R are also driven in different directions at different speeds or at the same speed.

At this time, if the amount of operation of the steering lever 39 is maximum, the control device 50 determines the inside/outside speed ratio to -1. As described above, the control device 50 determines the drive direction and drive speed of the inside traveling device and the outside traveling device, respectively, determines the target speed change positions of the continuously variable transmissions 21 and 22, and changes the speed of the continuously variable transmissions 21 and 22. As a result, the constant displacement motors M1 and M2 are driven in different directions at the same speed, and the left and right traveling devices 1L and 1R are also driven in different directions at the same speed, performing a zero turn in which the vehicle 2 turns left or right with an extremely small turning radius that is close to zero.

Even if the zero-turn mode is being executed, if the operation amount of the steering lever 39 is not the maximum amount and the operation amount is not 0, the control device 50 sets the inside/outside speed ratio to a value greater than -1 and less than 1. As described above, the control device 50 determines the drive direction and drive speed of the traveling device on the inside of the turn and the traveling device on the outside of the turn, respectively, determines the target shift positions of the continuously variable transmissions 21 and 22, respectively, and performs shifting of the continuously variable transmissions 21 and 22.

As a result, the constant displacement motors M1, M2 are driven in different directions at different speeds, driven in the same direction at different speeds, or either of the constant displacement motors M1, M2 is stopped. The left and right traveling devices 1L, 1R are also driven in different directions at different speeds, driven in the same direction at different speeds, or either of the left and right traveling devices 1L, 1R is stopped. As a result, the machine body 2 turns left or right in a gentle turn, quasi-pivot turn, pivot turn, super pivot turn, or quasi-zero turn. A quasi-zero turn is a turn in which the turning radius of the machine body 2 is larger than a super pivot turn but smaller than a zero turn.

When performing a zero turn, as described above, the control device 50 drives the first running device 1L and the second running device 1R in different directions at the same driving speed using the steering device 10, but there may be a slight difference between the driving speed of the first running device 1L and the driving speed of the second running device 1R. In this case, the control device 50 drives the first running device 1L and the second running device 1R in different directions so that the absolute value of the difference between the actual driving speed of the first running device 1L and the actual driving speed of the second running device 1R detected by the rotation detection units 57, 60 is equal to or less than a predetermined threshold value close to 0, thereby performing a zero turn.

When performing a pivot turn, as described above, the control device 50 drives the traveling device 1L, 1R on the outside of the turn in a determined direction and speed, and sets the drive speed of the traveling device on the inside of the turn to 0, but the drive speed of the traveling device on the inside of the turn may be made slightly faster or slower than 0. In this case, the control device 50 controls the drive of the traveling device on the inside of the turn by the steering device 10 so that the absolute value of the actual drive speed of the traveling device on the inside of the turn detected by the rotation detection units 57, 60 is equal to or less than a predetermined threshold value close to 0, thereby performing a pivot turn.

In addition, when the working device 1 turns, the control device 50 may detect the actual driving speed of the traveling devices 1L, 1R using the rotation detection units 57, 60, and operate the steering device 10 by performing PI control or the like so that the actual driving speed matches the determined driving speed (target speed) of the traveling devices 1L, 1R.
FIG. 4 is a flow chart showing the swing operation of the work machine 100.

When the control device 50 detects that the mode selection switch 40 has been operated (S1: Yes), it executes a turn mode selection process (S2). In the turn mode selection process, the control device 50 detects the position of the mode selection switch 40 after operation based on the output signal from the switch mechanism 45, and further detects the turn mode corresponding to the position after the operation, and determines that the turn mode has been selected.

When the zero turn mode is not selected (S3: No), when the steering lever 39 is operated (S6: Yes), the control device 50 executes the selected turn mode processing (gentle turn mode, pivot turn mode, or ultra-pivot turn mode) other than the zero turn mode (S7).
At this time, the control device 50 determines the driving direction and driving speed of the traveling devices 1L, 1R, the target speed change positions of the continuously variable transmissions 21, 22, and the inside/outside speed ratio based on the operating states of the steering lever 39, the main speed change lever 37, and the sub speed change lever 38, as described above. Then, the control device 50 changes the speed of the continuously variable transmissions 21, 22 using the valve units 51, 52 and the servo cylinders 55, 58, etc. When the accelerator lever 41 is swung in the accelerating direction, the control device 50 controls the continuously variable transmissions 21, 22 to make the actual driving direction and driving speed of the traveling devices 1L, 1R coincide or approximately coincide with the determined driving direction and driving speed (target speed) of the traveling devices 1L, 1R, respectively, and turns the vehicle body 2 left or right in a gentle turn, a quasi-pivot turn, a pivot turn, or a super-pivot turn.

On the other hand, when the zero turn mode is selected (S3: Yes), if the steering lever 39 is operated (S4: Yes), the control device 50 executes the zero turn mode process (S5).
FIG. 5 is a flowchart showing the details of the zero turn mode process.
First, the control device 50 executes an aircraft state determination process (S8). In the aircraft state determination process, the control device 50 compares the speed of the aircraft 2 detected by, for example, the speed detection unit 62 (FIG. 2) with a pre-stored predetermined speed. The predetermined speed is set to 0 or an extremely low speed close to 0.

If the speed of the aircraft 2 is faster than the predetermined speed, the control device 50 determines that the aircraft 2 is in an unstable state (S9: No), prohibits a zero turn, and records the result in the internal memory (S10 in FIG. 5).
On the other hand, if the speed of the aircraft 2 is equal to or lower than the predetermined speed, the aircraft 2 is in a stopped or substantially stopped state, and the control device 50 determines that the aircraft 2 is in a stable state (S9: Yes). Then, the control device 50 checks the amount of operation of the steering lever 39.

If the steering lever 39 is swung in the left or right turning direction by an amount less than the maximum amount immediately before the process S4 in FIG. 4 described above, the control device 50 confirms that the amount of operation of the steering lever 39 is not the maximum (S11 in FIG. 5: No), prohibits zero turn, and records the result in the internal memory (S13).
On the other hand, if the steering lever 39 has been swung to the maximum extent in the left or right turning direction immediately before processing S4 in FIG. 4, the control device 50 confirms that the steering lever 39 has been operated to the maximum extent (S11 in FIG. 5: Yes), permits zero turn, and turns on a zero turn flag provided in a specified storage area of the internal memory (S12).

When the accelerator lever 41 is swung in the acceleration direction (S14: Yes), the control device 50 checks whether the zero turn flag is on. If the zero turn flag is on (S15: Yes), the control device 50 executes a zero turn (S16).
At this time, the control device 50 determines the drive direction and drive speed of the traveling device on the outside of the left and right traveling devices 1L, 1R based on the operation direction and operation amount of the steering lever 39. The control device 50 also determines the inside/outside speed ratio to be -1, and multiplies the inside/outside speed ratio by the drive speed of the traveling device on the outside of the turn to determine the drive speed of the traveling device on the inside of the turn. The control device 50 also determines the direction opposite to the drive direction of the traveling device on the outside of the turn as the drive direction of the traveling device on the inside of the turn. Then, the control device 50 drives the traveling device on the outside of the turn and the traveling device on the inside of the turn with the steering device 10 in the determined drive direction and drive speed, and executes a zero turn to the left or right of the vehicle body 2. When the zero turn is completed, the control device 50 turns off the zero turn flag (S17).

On the other hand, if the zero turn flag is not on (S15: No), the control device 50 executes a turn other than a zero turn (S18).
At this time, the control device 50 determines the drive direction and drive speed of the traveling device on the outside of the left and right traveling devices 1L, 1R based on the operation direction and operation amount of the steering lever 39. The control device 50 also determines the inside/outside speed ratio to a value somewhat larger than -1. The control device 50 also multiplies the inside/outside speed ratio by the drive speed of the traveling device on the outside of the turn to determine the drive speed of the traveling device on the inside of the turn. The control device 50 also determines the direction opposite to the drive direction of the traveling device on the outside of the turn as the drive direction of the traveling device on the inside of the turn. The control device 50 then drives the traveling device on the outside of the turn and the traveling device on the inside of the turn with the steering device 10 in the determined drive direction and drive speed, and turns the vehicle 2 left or right in a turn other than a zero turn (quasi-zero turn, super-pivot turn, pivot turn, quasi-pivot turn, or gentle turn).

More specifically, for example, at this time, the control device 50 drives the outside running device of the first running device 1L and the second running device 1R with the steering device 10 based on the operation state (operation direction and operation amount) of the steering lever 39, and drives the inside running device with the steering device 10 at a drive speed slower than the drive speed of the outside running device in the drive direction opposite to that of the outside running device, thereby executing a quasi-zero turn or a pivot turn.

Alternatively, based on the operating state of the steering lever 39, the control device 50 drives the traveling device on the outside of the turn via the steering device 10, and drives the traveling device on the inside of the turn via the steering device 10 at a driving speed that is slower than the driving speed of the traveling device on the outside of the turn by a predetermined ratio, in a driving direction opposite to that of the traveling device on the outside of the turn, thereby performing a quasi-zero turn or a pivot turn.
In addition, the control device 50 makes the difference between the drive speed of the running device on the outside of the turn and the drive speed of the running device on the inside of the turn when performing a quasi-zero turn or a pivot turn in the above cases (the amount by which the drive speed of the running device on the inside of the turn is slowed relative to the drive speed of the running device on the outside of the turn) greater than a threshold value that suppresses the difference between the drive speed of the running device on the outside of the turn and the drive speed of the running device on the inside of the turn when performing a zero turn.

As another example, in the aircraft state determination process of process S3, the control device 50 may compare the tilt angle of the aircraft 2 detected by the tilt detection unit 63 (Figure 2) with a predetermined angle, and if the tilt angle of the aircraft 2 is equal to or less than the predetermined angle, determine that the aircraft 2 is in a stable state (S9 in Figure 5: Yes), and if the tilt angle of the aircraft 2 is greater than the predetermined angle, determine that the aircraft 2 is in an unstable state (S9: No).

The control device 50 may also compare the lifting height of the harvesting device 3 (FIG. 6) from the ground, detected by the lifting position detection unit 64 (FIG. 2), with a predetermined height, and if the lifting height of the harvesting device 3 is less than the predetermined height, determine that the center of gravity of the working machine 100 is low and the machine body 2 is stable (S9 in FIG. 5: Yes), and if the lifting height of the harvesting device 3 is equal to or greater than the predetermined height, determine that the center of gravity of the working machine 100 is high and the machine body 2 is unstable (S9: No).

For example, when the object detection unit 65 (FIG. 2) detects that there is an obstacle in the vicinity that may come into contact with parts of the work machine 100 when the work machine 100 performs a zero turn, the control device 50 may determine that the machine 2 is in an unstable state (S9: No in FIG. 5), and if the obstacle is not detected by the object detection unit 65, the control device 50 may determine that the machine 2 is in a stable state (S9: Yes).

The control device 50 may also determine whether the airframe 2 is in a stable state based on stability conditions other than those described above. Furthermore, the control device 50 may determine whether the airframe 2 is in a stable state based on the suitability of two or more of the stability conditions described above.
The control device 50 may also evaluate the stability of the vehicle 2 in multiple stages based on the stability conditions as described above, and determine a turn to be performed instead of a zero turn in process S17 based on the evaluation result. In this case, for example, the control device 50 may increase the inside/outside speed ratio to increase the turning radius of the vehicle 2 as the stability of the vehicle 2 decreases. Also, for example, if the stability of the vehicle 2 is too low, the control device 50 may not execute turning of the vehicle 2 by the steering device 10.

In the above embodiment, the mode selection switch 40 is used, which can select one of the gentle turn mode, the pivot turn mode, the super pivot turn mode, and the zero turn mode by swinging the operation knob to four positions, but instead of this, other types of operation units such as a push button type, a dial type, a lever type, or a soft key displayed on a touch panel may be used as the mode selection unit. Also, the number of executable turn modes other than the zero turn mode is not limited to the above three, and one, two, four or more may be provided.

Also, other types of operating members, such as a push button type, a dial type, a handle type, or a touch panel capable of displaying soft keys, may be used instead of the main speed change lever 37, the sub speed change lever 38, the steering lever 39, or the accelerator lever 41. Also, an operating member such as a joystick that serves both as a steering lever and an accelerator lever may be used.
In the above-described embodiment, the drive speed of the first running device 1L on the left side of the machine body 1 and the drive speed of the second running device 1R on the right side are changed separately by the first continuously variable transmission device 21 and the second continuously variable transmission device 22, but this configuration is not limited to this.

As another example, a single continuously variable transmission, multiple clutches corresponding to each turn, multiple brake mechanisms corresponding to each traveling device, multiple actuators, multiple solenoid valves, etc. may be provided. In this case, the speed change of the single continuously variable transmission, the on/off of each clutch, and the braking and release of each brake mechanism may be controlled via solenoid valves and actuators to change the drive speed of the first traveling device and the drive speed of the second traveling device, respectively, thereby realizing multiple turns including zero turns.

Alternatively, a continuously variable transmission for traveling, a continuously variable transmission for turning, multiple clutches for turning, multiple actuators, solenoid valves, etc. may be provided, and the speed changes of each continuously variable transmission and the switching on and off of each clutch may be controlled via the solenoid valves and actuators, thereby changing the drive speed of the first traveling device and the drive speed of the second traveling device, respectively, to achieve multiple turns including zero turns.
In the embodiment described above, the same control device 50 performs the permission/prohibition of zero turns and the control of the traveling units 1L, 1R, but instead, the permission/prohibition of zero turns and the control of the traveling units 1L, 1R may be configured to be performed by separate control devices.

In the above-described embodiment, the speed of the machine body 2 is detected by the speed detection unit 62, but instead, for example, the control device 50 may calculate the speed of the machine body 2 based on the rotation speeds of the constant displacement motors M1, M2 detected by the rotation detection units 57, 60. Alternatively, a drive speed detection unit may be provided that detects the actual drive speeds of the traveling units 1L, 1R, respectively, and the control device 50 may calculate the speed of the machine body 2 based on the drive speeds of the traveling units 1L, 1R detected by the drive speed detection units.
In the above-described embodiment, the track-type traveling devices 1L and 1R are used. However, instead of this, a wheeled traveling device may be used, or a traveling device in which wheels and crawlers are combined may be used.

The working machine 100 of the present embodiment described above has the following configuration and provides the following effects.
The working machine 100 of this embodiment is equipped with a first traveling device 1L that supports the machine body 2 on the left side of the machine body 2 so that the machine body 2 can travel, a second traveling device 1R that supports the machine body 2 on the right side of the machine body 2 so that the machine body 2 can travel, and a steering device 10 that includes operating members 37, 38, 39, 41 (main speed change lever 37, sub speed change lever 38, steering lever 39, accelerator lever 41) for operating the traveling and steering of the machine body 2, the steering device 10 driving the first traveling device 1L and the second traveling device 1R respectively according to the operating states of the operating members 37, 38, 39, 41 to make the machine body 2 travel straight or turn, and a control device 50 that determines whether the machine body 2 is in a stable state. When the operating member 39 (steering lever 39) is operated to the maximum extent either to the left or right and it is determined that the vehicle 2 is in a stable state, the steering device 10 drives the first running device 1L and the second running device 1R in different directions at the same driving speed, or drives the first running device 1L and the second running device 1R in different directions so that the absolute value of the difference between the driving speed of the first running device 1L and the driving speed of the second running device 1R is below a predetermined threshold value, thereby permitting a zero turn in which the vehicle 2 turns with an extremely small turning radius that is close to zero, and when the operating member 39 is operated to the maximum extent either to the left or right or when it is determined that the vehicle 2 is not in a stable state, the zero turn is prohibited.

As described above, in the working machine 100, when the operating member 39 (steering lever 39) is operated to the maximum extent only when the body 2 is in a stable state, a zero turn in which the body 2 turns with an extremely small turning radius is permitted, thereby improving safety during the execution of a zero turn and improving the convenience of turning.
In this embodiment, the work machine 100 is equipped with operation detection units 42, 43, 44, 46 (potentiometers 42, 44, 46, switch mechanism 43) that detect the operation states of the operating members 37, 38, 39, 41, the steering device 10 transmits the power output from the prime mover 5 provided on the machine body 2 to at least one of the first traveling device 1L and the second traveling device 1R according to the operation states of the operating members 37, 38, 39, 41 to drive the traveling device, and when the control device 50 permits a zero turn, it controls the steering device 10 based on the operation states of the operating members 37, 38, 39, 41 to perform a zero turn. As a result, only when the machine body 2 is in a stable state, when the operating member 39 (steering lever 39) is operated to the maximum extent, the control device 50 permits a zero turn and a zero turn can be performed.

In this embodiment, when the control device 50 determines that the operating member 39 (steering lever 39) is operated to the maximum extent to the left or right and the vehicle body 2 is not in a stable state, the control device 50 drives the outside running device of the first running device 1L and the second running device 1R, which is located farther from the turning center of the vehicle body 2, by the steering device 10 based on the operating state of the operating members 37, 38, 39, and 41, and drives the inside running device, which is located closer to the turning center of the vehicle body 2, by the steering device 10 at a driving speed slower than the driving speed of the outside running device in the driving direction opposite to the outside running device. As a result, when the vehicle body 2 is not in a stable state, if the operating member 39 is operated to the maximum extent, the vehicle body 2 turns with a turning radius larger than zero turn, so that the shaking and vibration of the vehicle body 2 during the turn can be reduced, and the safety and convenience of turning in the work machine 100 can be improved.

In this embodiment, when the operating member 39 (steering lever 39) is operated to the left or right by an amount less than the maximum amount, the control device 50 drives the outside traveling device of the first traveling device 1L and the second traveling device 1R, which is located farther from the turning center of the machine body 2, by the steering device 10 based on the operating state of the operating members 37, 38, 39, 41, and drives the inside traveling device of the machine body 2, which is located closer to the turning center of the machine body 2, by the steering device 10 at a driving speed slower by a predetermined ratio (inside/outside speed ratio) than the driving speed of the outside traveling device, in the driving direction opposite to that of the outside traveling device. As a result, when the operating member 39 (steering lever 39) is operated by an amount less than the maximum amount, the machine body 2 turns with a turning radius larger than a zero turn, reducing the shaking and vibration of the machine body 2 during the turn, and improving the safety and convenience of turning in the work machine 100.

In this embodiment, at least one of the first running device 1L and the second running device 1R is driven by the steering device 10 so that the drive speed of the inside running device located closer to the turning center of the machine body 2 is zero or slower than the drive speed of the outside running device located farther from the turning center of the machine body 2, and a first turn mode (super-pivot turn mode, pivot turn mode, or gentle turn mode) in which another turn (quasi-zero turn, super-pivot turn, pivot turn, quasi-pivot turn, gentle turn) in which the machine body 2 turns with a turning radius larger than the turning radius in a zero turn can be performed, and a second turn mode (zero turn mode) in which a zero turn can be performed. ) and the control device 50 is provided with a mode selection unit 40 (mode selection switch 40) that can select one of the turn modes. When the first turn mode is selected by the mode selection unit 40, the control device 50 controls the steering device 10 based on the operation state of the operating members 37, 38, 39, and 41 to execute the other turn. When the second turn mode is selected by the mode selection unit 40, the operating member 39 (steering lever 39) is operated to the maximum extent to the left or right, and it is determined that the aircraft 2 is in a stable state, the control device 50 permits a zero turn and controls the steering device 10 based on the operation state of the operating members 37, 38, 39, and 41 to execute a zero turn.

As described above, the second turn mode (zero turn mode) is selected by the mode selection unit 40 (mode selection switch 40), and only when the machine body 2 is in a stable state, a zero turn is permitted when the operating member 39 (steering lever 39) is operated to the maximum extent. This allows a zero turn to be stably performed according to the user's intention, and makes it possible to further improve the safety and convenience of turning in the work machine 1.

In this embodiment, when the first turn mode is selected by the mode selection unit 40 (mode selection switch 40), the control device 50 controls the steering device 10 based on the operation state of the operating members 37, 38, 39, 41 to execute another turn (quasi-zero turn, super-pivot turn, pivot turn, quasi-pivot turn, gentle turn). This allows the working machine 100 to execute a turn other than a zero turn according to the user's intention, making it possible to further improve the convenience of turning.

In this embodiment, as the first turn mode, a super-pivot turn mode in which the machine body 2 can be turned in a pivotal direction, a pivot turn mode in which the machine body 2 can be turned in a pivotal direction, or a gentle turn mode in which the machine body 2 can be turned in a gentle direction can be selected by the mode selection unit 40 (mode selection switch 40). This allows the user to select one of the gentle turn mode, pivot turn mode, super-pivot turn mode, and second turn mode (zero turn mode) by the mode selection unit 40, and to perform gentle turns, pivot turns, super-pivot turns, zero turns, etc. on the work machine 100, thereby making it possible to further improve the convenience of turning.

In this embodiment, the work machine 100 is equipped with a speed detection unit 62 that detects the speed of the machine body 2, and the control device 50 determines that the machine body 2 is in a stable state if the speed of the machine body 2 is equal to or lower than a predetermined speed, and determines that the machine body 2 is not in a stable state if the speed of the machine body 2 is higher than the predetermined speed. As a result, when the machine body 2 is stopped or the speed of the machine body 2 is slow, if the operating member 39 (steering lever 39) is operated to the maximum extent, a zero turn is permitted, and the frictional force between each traveling device 1L, 1R and the road surface is evenly and gradually increased during the execution of the zero turn, thereby reducing the swaying and vibration of the machine body 2 and further improving safety.

In this embodiment, the first traveling device 1L and the second traveling device 1R are each configured as a track-type traveling device, the steering device 10 includes continuously variable transmissions 21, 22 that continuously change the drive speed of the first traveling device 1L and the drive speed of the second traveling device 1R, respectively, and the control device 50 changes the drive speed and drive direction of the first traveling device 1L and the second traveling device 1R by controlling the speed change of the continuously variable transmissions 21, 22. This allows the drive speed of the first traveling device 1L and the drive speed of the second traveling device 1R to be precisely controlled, and the work machine 100 can reliably perform gentle turns, pivot turns, super pivot turns, and zero turns.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all modifications within the meaning and scope of the claims, including equivalents, are included.

REFERENCE SIGNS LIST 1 Travel device 1L First travel vehicle body 1R Second travel device 2 Machine body 5 Prime mover 10 Steering device 21 First variable speed device (variable speed device)
22 Second variable speed device (variable speed device)
37 Main shift lever (operating member)
39 Steering lever (operating member)
40 Mode selection switch (mode selection section)
41 Accelerator lever (operating member)
42, 44, 46 Potentiometer (operation detection unit)
43 Switch mechanism (operation and detection unit)
50 Control device 62 Speed detection unit 100 Working machine

Claims (8)

A first traveling device that supports the machine body so that the machine body can travel on a left side of the machine body;
A second traveling device that supports the machine body so that the machine body can travel on a right side of the machine body;
A steering device including an operating member for operating the traveling and steering of the vehicle, the steering device driving each of the first traveling device and the second traveling device in accordance with the operating state of the operating member to move the vehicle in a straight line or turn;
A control device for determining whether the aircraft is in a stable state,
The control device includes:
When it is determined that the operating member is operated to the maximum extent to the left or right and the vehicle is in a stable state, the steering device drives the first traveling device and the second traveling device in different directions at the same driving speed, or drives the first traveling device and the second traveling device in different directions so that the absolute value of the difference between the driving speed of the first traveling device and the driving speed of the second traveling device is equal to or less than a predetermined threshold value, thereby permitting a zero turn in which the vehicle turns with an extremely small turning radius that is close to zero;
When the operating member is operated to the left or right by an amount less than the maximum amount, or when it is determined that the aircraft is not in a stable state, the zero turn is prohibited ;
When the operating member is operated to the maximum extent to the left or right and it is determined that the machine body is not in a stable state, based on the operating state of the operating member, the outside running device of the first and second running devices, which is located farther from the center of rotation of the machine body, is driven by the steering device, and the inside running device, which is located closer to the center of rotation of the machine body, is driven by the steering device in the driving direction opposite to that of the outside running device at a driving speed slower than the driving speed of the outside running device . an operation detection unit that detects an operation state of the operation member,
the steering device transmits power output from a prime mover provided on the vehicle body to at least one of the first traveling device and the second traveling device in accordance with an operation state of the operating member to drive the traveling device;
The work machine according to claim 1 , wherein when the control device permits the zero turn, the control device controls the steering device based on an operation state of the operation member to execute the zero turn. 3. The work machine according to claim 1 or 2, wherein, when the operating member is operated to the left or right by an amount less than the maximum amount, the control device drives, based on the operating state of the operating member, the outside running device of the first or second running device that is located farther from the center of rotation of the machine body, using the steering device, and drives the inside running device that is located closer to the center of rotation of the machine body, using the steering device, in a driving direction opposite to that of the outside running device, at a driving speed that is slower by a predetermined ratio than the driving speed of the outside running device. a mode selection unit that can select one of a first turn mode in which a different turn can be performed in which the vehicle is turned with a turning radius larger than the turning radius in the zero turn by driving at least one of the first and second traveling devices by the steering device so that the driving speed of the inside traveling device located near the turning center of the vehicle is zero or is slower than the driving speed of the outside traveling device located far from the turning center of the vehicle, and a second turn mode in which the zero turn can be performed;
The control device includes:
When the first turn mode is selected by the mode selection unit, the steering device is controlled based on an operation state of the operation member to execute the different turn,
4. The work machine according to claim 1, wherein when the second turn mode is selected by the mode selection unit, and the operating member is operated to the maximum extent to the left or right, and it is determined that the machine body is in a stable state, the zero turn is permitted, and the steering device is controlled based on the operation state of the operating member to execute the zero turn . The work machine according to claim 4 , wherein, when the first turn mode is selected by the mode selection unit, the control device controls the steering device based on an operation state of the operating member to execute the different turn. The work machine according to claim 4 or 5, wherein the first turn mode can be selected by the mode selection unit from a super-pivot turn mode in which the vehicle can perform a super-pivot turn, a pivot turn mode in which the vehicle can perform a pivot turn, or a gentle turn mode in which the vehicle can perform a gentle turn . A speed detection unit is provided to detect the speed of the aircraft,
The work machine according to any one of claims 1 to 6, wherein the control device determines that the machine is in a stable state if the speed of the machine is equal to or lower than a predetermined speed, and determines that the machine is not in a stable state if the speed of the machine is faster than the predetermined speed . The first traveling device and the second traveling device are each composed of a track-type traveling device,
the steering device includes a continuously variable transmission that continuously changes a drive speed of the first traveling device and a drive speed of the second traveling device,
The work machine according to any one of claims 1 to 7 , wherein the control device changes the drive speeds and drive directions of the first traveling device and the second traveling device by controlling the speed change of the continuously variable transmission.

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