Work vehicles

Abstract

To improve traveling performance at a start, in a working vehicle having a continuously variable transmission.SOLUTION: A working vehicle comprises: a vehicle body; a prime motor; a continuously variable transmission; a planetary transmission part for outputting a synthesized drive force which is obtained by synthesizing a drive force which is gear-changed by the continuously variable transmission and a drive force from the primary motor; a traveling operation member 148 which is operable to a forward position F, a retreat position R and a neutral position N of the vehicle body; a clutch mechanism for switching the synthesized drive force outputted from the planetary transmission part on the basis of the operation of the traveling operation member 148 to the forward position F, the retreat position R and the neutral position N; a storage device 121 for storing a control map CM1 in advance indicating a relationship between a traveling speed of the vehicle body and the drive force outputted from the continuously variable transmission; and a control device 120 for setting a neutral target value being the drive force outputted from the continuously variable transmission when holding the traveling operation member 148 to the neutral position N on the basis of the control map CM1.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a work vehicle such as a tractor.

Background Art

[0002] Conventionally, as a tractor equipped with a continuously variable transmission, the one shown in Patent Document 1 is known. The tractor disclosed in Patent Document 1 has a hydraulic pump and a hydraulic motor, and a hydrostatic continuously variable transmission unit that inputs the power of the engine, and variably transmits the input power to power with a stepless rotational speed and outputs it, and a compound planetary transmission unit that synthesizes the input transmission output and the engine power and outputs the synthesized power.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a tractor as shown in Patent Document 1, the connection of the compound planetary transmission unit when the tractor is braked is not considered, and the behavior (travel) of the tractor at the time of starting (for example, when starting with braking) may change, and improvement in the drivability at the time of starting is required. Therefore, in view of the above problems, the present invention aims to improve the drivability at the time of starting in a work vehicle equipped with a continuously variable transmission.

Means for Solving the Problems

[0005] The present invention employs the following technical means to achieve the above object. The work vehicle includes a vehicle body having a traveling device, a prime mover, a hydraulic pump having a swash plate whose output is changed by a swash plate angle, a traveling motor having an output shaft whose rotational speed changes according to the output of the hydraulic pump and outputting the driving force of the output shaft, a continuously variable transmission device, a planetary transmission unit that outputs a combined driving force obtained by combining the driving force transmitted by the continuously variable transmission device and the driving force from the prime mover, a forward position for moving the vehicle body forward, a reverse position for moving the vehicle body backward, a neutral position where the vehicle body is not switched to either forward or backward, a traveling operation member that can be operated to these positions, a clutch mechanism that switches the combined driving force output from the planetary transmission unit based on the operation of the forward position, reverse position, and neutral position of the traveling operation member, in a coordinate system where a first axis indicating the traveling speed of the vehicle body and a second axis indicating the driving force output from the continuously variable transmission device are orthogonal at the origin, a first line for moving the vehicle body forward at a first speed or less, extending from a predetermined negative minimum value of the second axis to the positive side of the first axis and inclined with respect to the second axis, and a second line for moving the vehicle body backward, extending from the minimum value of the second axis to the negative side of the first axis and inclined at an inclination angle larger than the inclination angle of the first line with respect to the second axis, a storage device that stores in advance a control map including these, and a control device that sets a neutral target value, which is the driving force output from the continuously variable transmission device when the traveling operation member is held in the neutral position, based on the control map. The control map further includes a third line that extends from the minimum value of the second axis to the positive side of the first axis and slopes at an inclination angle greater than the inclination angle of the first line with respect to the second axis, for advancing the vehicle body at a second speed higher than the first speed. When advancing the vehicle body at the first speed, the control device sets a neutral target value, which is the driving force output from the continuously variable transmission when the travel operation member is held at the neutral position, based on the control map. When advancing the vehicle body at the second speed, the control device does not set the neutral target value 。

[0007] Preferably, the work vehicle includes a braking operation member and a braking device that brakes the traveling device according to the operation of the braking operation member, and the control device changes the neutral target value, which is the driving force output from the continuously variable transmission device when the traveling operation member is held in the neutral position, according to the operation amount of the braking operation member. Preferably, the control device decreases the neutral target value as the operation amount increases and increases the neutral target value as the operation amount decreases.

[0008] Preferably, the control device includes a target calculation unit that calculates a forward target output value output from the continuously variable transmission when the traveling operation member is switched from the neutral position to the forward position to move the vehicle body forward, and a reverse target output value output from the continuously variable transmission when the traveling operation member is switched from the neutral position to the reverse position to move the vehicle body backward, and an output setting unit that sets the neutral target value based on the operation amount of the braking operation member, the forward target output value, and the reverse target output value.

[0009] Preferably, the control device includes a target calculation unit that calculates a forward target output value output from the continuously variable transmission when the traveling operation member is switched from the neutral position to the forward position to move the vehicle body forward, and a reverse target output value output from the continuously variable transmission when the traveling operation member is switched from the neutral position to the reverse position to move the vehicle body backward, and an output setting unit that sets the neutral target value based on a first target value that is the forward target output value when switched to the forward position without operating the braking operation member, and a second target value that is the reverse target output value when switched to the reverse position without operating the braking operation member.

[0010] Preferably, the output setting unit sets an intermediate value between the first target value and the second target value as the neutral target value. Preferably, the prime mover outputs a driving force that is constant at a predetermined rotational speed, and the output setting unit sets the rotational speed of the traveling motor as the driving force output from the continuously variable transmission.

[0011] Preferably, the clutch mechanism includes a first clutch device that can switch between a connected state in which the combined driving force of the planetary transmission unit is transmitted to the forward side at the second speed and a disconnected state in which the combined driving force is not transmitted to the forward side, and a second clutch device that can switch between a connected state in which the combined driving force of the planetary transmission unit is transmitted to the forward side at the first speed, a connected state in which the combined driving force of the planetary transmission unit is transmitted to the reverse side, and a disconnected state in which the combined driving force is not transmitted to either the forward side or the reverse side. When the control device sets the first clutch device to the connected state, the second clutch device is set to the disconnected state, and when the control device sets the second clutch device to the connected state, the first clutch device is set to the disconnected state.

Advantages of the Invention

[0012] According to the present invention, in a work vehicle equipped with a continuously variable transmission, the running performance at the start can be improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5A

Figure 5B

Figure 6

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 6 shows a tractor which is an example of a work vehicle. In the present embodiment, the tractor is taken as an example of the work vehicle 1 for description, but the work vehicle 1 is not limited to the tractor and may be an agricultural machine such as a rice transplanter. As shown in FIG. 6, the work vehicle 1 includes a vehicle body 3 having a traveling device 7, a prime mover 4, a transmission 5, and a steering device 29. The traveling device 7 is a device having front wheels 7F and rear wheels 7R. The front wheels 7F may be of a tire type or a crawler type. Also, the rear wheels 7R may be of a tire type or a crawler type. The prime mover 4 is an internal combustion engine such as a gasoline engine or a diesel engine. In this embodiment, the prime mover 4 is a diesel engine.

[0015] The transmission 5 can switch the driving force of the traveling device 7 by shifting gears and can also switch the forward and reverse of the traveling device 7. A cabin 9 is provided on the vehicle body 3, and a driver's seat 10 is provided inside the cabin 9. In addition, a lifting device 8 is provided at the rear of the vehicle body 3. The work device 2 can be attached to and detached from the lifting device 8. Also, the lifting device 8 can lift the attached work device 2. The work device 2 is a tilling device for tilling, a fertilizer spreading device for spreading fertilizers, a pesticide spraying device for spraying pesticides, a harvesting device for harvesting, a mowing device for mowing grass and the like, a spreading device for spreading grass and the like, a grass collecting device for collecting grass and the like, a shaping device for shaping grass and the like, and the like.

[0016] As shown in FIG. 1, the transmission 5 is a device that can change the driving force from the prime mover 4 and transmit it to the traveling device 7. The transmission 5 includes a continuously variable transmission 50, a planetary transmission unit 60, a clutch mechanism 52, and a sub-transmission mechanism 53. The transmission 5 is housed in the transmission case 12. As shown in FIG. 4, the transmission case 12 has a cubic shape with a space, and includes an upper wall 12A, a lower wall 12B provided spaced apart from the upper wall 12A, a left side wall 12C connecting the left sides of the upper wall 12A and the lower wall 12B, a right side wall 12D connecting the right sides of the upper wall 12A and the lower wall 12B, a front wall 12E connecting the front sides of the upper wall 12A, the lower wall 12B, the left side wall 12C, and the right side wall 12D, and a rear wall 12F connecting the rear sides of the upper wall 12A, the lower wall 12B, the left side wall 12C, and the right side wall 12D. As shown in FIG. 4, the continuously variable transmission 50, the planetary transmission unit 60, the clutch mechanism 52, and the sub-transmission mechanism 53 are housed in the space surrounded by the upper wall 12A, the lower wall 12B, the left side wall 12C, the right side wall 12D, the front wall 12E, and the rear wall 12F. The transmission case 12 may have a structure in which a plurality of divided bodies are connected, and is not limited thereto.

[0017] The inside of the transmission case 12 is filled with lubricating oil for lubricating the transmission 5 (continuously variable transmission 50, planetary transmission unit 60, clutch mechanism 52, and sub-transmission mechanism 53). The continuously variable transmission 50 is a device that continuously changes the driving force transmitted from the prime mover 4. In this embodiment, the continuously variable transmission 50 is a hydrostatic continuously variable transmission 50. Now, the transmission 5 has a four-speed transmission with two stages of Hi / Lo of the clutch mechanism 52 that switches between a high-speed range (Hi) and a low-speed range (Lo) according to the position of the main transmission operation member 147 (main transmission lever), and two stages of the sub-transmission mechanism that is manually switched by the sub-transmission operation member 149 (sub-transmission lever).

[0018] The output shaft (crankshaft) 4a of the prime mover 4 is connected to the main shaft (propulsion shaft) 54. The rotation of the output shaft (crankshaft) 4a of the prime mover 4 is transmitted to the main shaft (propulsion shaft) 54. A drive gear 59 is provided on the main shaft (propulsion shaft) 54. The drive gear 59 rotates as the main shaft (propulsion shaft) 54 rotates. A first gear 59a and a second gear 59b are respectively meshed with the drive gear 59. The first gear 59a is a gear provided on the input shaft 56a of the hydraulic pump P1 of the continuously variable transmission 50. Also, an output shaft 59c is connected to the second gear 59b. An input gear 62 of the planetary transmission part 60 is provided at the output side end of the output shaft 59c (that is, the end opposite to the end where the second gear 59b of the output shaft 59c is located).

[0019] The continuously variable transmission 50 changes the driving force transmitted from the output shaft (crankshaft) 4a of the prime mover 4 to the main shaft (propulsion shaft) 54, the drive gear 59, and the first gear 59a. As shown in FIGS. 1 and 2, the continuously variable transmission 50 has a hydraulic pump P1 and a travel motor M1. The hydraulic pump P1 and the travel motor M1 are connected by an oil passage (circulation oil passage) 55 through which hydraulic oil flows. The hydraulic pump P1 has an input shaft 56a and a swash plate 56b. The hydraulic pump P1 is driven by the power transmitted to the input shaft 56a, and the output (discharge amount (flow rate), pressure of the hydraulic oil) can be changed by the angle (swash plate angle) of the swash plate 56b that is swingably supported.

[0020] The travel motor M1 is a motor capable of forward and reverse rotation and has an output shaft 58. The rotation speed of the output shaft 58 changes according to the output (flow rate, pressure of the hydraulic oil) of the hydraulic pump P1. The driving force of the output shaft 58 is combined with the driving force from the prime mover 4 in the planetary transmission part 60. The combined driving force output from the planetary transmission part 60 is transmitted to the traveling device 7 after being transmitted to the clutch mechanism 52, the auxiliary transmission mechanism 53, etc.

[0021] Specifically, as shown in FIG. 1, the input shaft 56a of the hydraulic pump P1 is where the power of the prime mover 4 is transmitted It is connected to the first gear 59a that is reached. That is, the power of the main shaft (propulsion shaft) 54 is transmitted to the input shaft 56a of the hydraulic pump P1 via the drive gear 59 and the first gear 59a. The output is changed according to the swash plate angle of the hydraulic pump P1, and the rotational speed of the output shaft 58 of the travel motor M1 is changed.

[0022] The planetary transmission unit 60 is a planetary gear device that outputs a combined driving force obtained by combining the driving force shifted by the continuously variable transmission 50 and the driving force from the prime mover 4. The planetary transmission unit 60 includes an input gear 62 and a planetary gear mechanism 63. The input gear 62 is provided at the output-side end of the output shaft 59c to which the power from the prime mover 4 is transmitted. The planetary gear mechanism 63 includes a ring gear (internal gear) 63d, a sun gear 63b disposed at the center position of the circular front surface of the ring gear 63d and rotatable about the same axis as the rotation axis of the ring gear 63d, at least one or more planetary gears 63c rotatably disposed between the sun gear 63b and the ring gear 63d and meshing with the sun gear 63b and the ring gear 63d, and a carrier 63a rotatable about the same axis as the rotation axis of the ring gear 63d and supporting the planetary gear 63c so as to be movable in the circumferential direction of the ring gear 63d. The carrier 63a meshes with the input gear 62, and the power from the prime mover 4 is transmitted thereto. The sun gear 63b is connected to the output shaft 58 of the travel motor M1. A combined output shaft 64, which is the rotation axis, is provided on the rear surface of the ring gear 63d (the surface opposite to the front surface where the carrier 63a is located). Therefore, the planetary gear mechanism 63 combines the power transmitted to the sun gear 63b (that is, the driving force shifted by the continuously variable transmission 50) and the power transmitted to the planetary gear 63c via the carrier 63a (that is, the driving force of the prime mover 4 that does not receive the speed change action by the continuously variable transmission 50), and outputs this combined driving force from the combined output shaft 64. Further, the planetary gear mechanism 63 can generate two types of combined driving forces (for example, a combined driving force for the low speed range or a combined driving force for the high speed range).

[0023] Therefore, the planetary transmission unit 60 outputs a combined driving force obtained by combining the driving force (the power of the output shaft 58 of the traveling motor M1) shifted by the continuously variable transmission 50 and the power from the prime mover 4 (the power via the output shaft (crankshaft) 4a of the prime mover 4, the main shaft (propulsion shaft) 54, the drive gear 59, the second gear 59b, and the output shaft 59c) to the combined output shaft 64. For example, the prime mover 4 can output a driving force that is constant at a predetermined rotational speed. The prime mover 4 can output, for example, an output value A1 indicating a driving force with a constant rotational speed in the forward rotation, and at this time, the output value A1 and the rotational speed are represented as “+100%”. The continuously variable transmission 50 changes the inclination angle of the swash plate 56b of the hydraulic pump P1 to an arbitrary inclination angle within the range of “-90 degrees” to “+90 degrees”, whereby the rotational speed of the traveling motor M1 is changed to an arbitrary rotational speed within the range from, for example, the reverse rotation of “-100%” to the forward rotation of “+100%”, and the driving force output from the continuously variable transmission 50 is changed to an output value B1 of an arbitrary value within the range of “-100%” to “+100%”. The output value A1 of “+100%” and the output value B1 of “+100%” are equal. The planetary transmission unit 60 can output a combined driving force that is a combined output value (for example, in the low speed case, an output value with a vehicle speed of “0” to “+50%”, and in the high speed case, an output value with a vehicle speed of “0” to “+100%”) obtained by multiplying the sum of the output value A1 of the prime mover 4 and the output value B1 of the continuously variable transmission 50 by a predetermined coefficient (for example, coefficient K1 = 0.25 at low speed and coefficient K2 = 0.5 at high speed). For example, at low speed, the combined output value = (output value A1 + output value B1) × coefficient K1 is calculated, and a combined driving force with an output value with a vehicle speed of “0” to “+50%” is output. Also, at high speed, the combined output value = (output value A1 + output value B1) × coefficient K2 is calculated, and a combined driving force with an output value with a vehicle speed of “0” to “+100%” is output. Note that the output values A1, B1, coefficient K1, and K2 are just examples and are not limited to these values.

[0024] As described above, according to the continuously variable transmission 50 and the planetary transmission unit 60, it is possible to output a combined driving force from the low speed range to the high speed range. As shown in Fig. 1, the transmission 5 is provided with a clutch mechanism 52. The clutch mechanism 52 can be switched between a connected state in which the combined driving force from the planetary transmission unit 60 is transmitted to the transmission shaft 66 and a disconnected state in which it is not connected to the transmission shaft 66. The clutch mechanism 52 includes an input shaft 62f connected to the combined output shaft 64 of the planetary transmission unit 60. The input shaft 62f rotates integrally with the combined output shaft 64 and rotates integrally therewith. A gear 72a is provided on the input shaft 62f. The gear 72a meshes with a gear 72b.

[0025] The clutch mechanism 52 has a first clutch device 52A and a second clutch device 52B. The first clutch device 52A is a clutch capable of transmitting the combined driving force in the high-speed range from the planetary transmission unit 60 to the transmission shaft 66. The second clutch device 52B is a clutch capable of transmitting the combined driving force in the low-speed range from the planetary transmission unit 60 to the transmission shaft 66. The first clutch device 52A and the second clutch device 52B are hydraulic clutches that are switched between a connected state and a disconnected state by hydraulic oil.

[0026] The first clutch device 52A will be described. The first clutch device 52A has a housing 71a, a cylindrical shaft 71b that can rotate integrally with the gear 72b, a friction plate 71c disposed between the housing 71a and the cylindrical shaft 71b, and a pressing member 71d. The pressing member 71d is biased in a direction away from the friction plate 71c by a biasing member such as a spring (not shown).

[0027] Inside the housing 71a, an oil passage 71e for supplying and discharging hydraulic oil is connected. When hydraulic oil is supplied from the oil passage 71e to the housing 71a side, the pressing member 71d moves toward the pressing side (connection side) against the biasing force of the spring, causing the friction plate 71c to press against the housing 71 side, and the first clutch device 52A enters the connected state. The combined driving force from the planetary transmission unit 60 (i.e., the power of the cylindrical shaft 71b rotating via the input shaft 62f, gear 72a, and gear 72b) is transmitted to the transmission shaft 66 that rotates integrally with the housing 71a. When the first clutch device 52A is in the connected state, the combined driving force in the high-speed range from the planetary transmission unit 60 is transmitted to the transmission shaft 66.

[0028] On the other hand, when hydraulic oil is discharged from the housing 71a side to the oil passage 71e, the pressing member 71d moves toward the disconnection side by the biasing force of the spring, causing the friction plate 71c to separate from the housing 71a side, and the first clutch device 52A enters the disconnected state. The power of the cylindrical shaft 71b rotating via the input shaft 62f, gear 72a, and gear 72b is not transmitted to the transmission shaft 66. The second clutch device 52B is a clutch for switching between forward and reverse, and has a forward clutch portion 75 and a reverse clutch portion 76. The second clutch device 52B has a housing 77 that rotates integrally with the input shaft 62f.

[0029] The forward clutch portion 75 has a cylindrical shaft 75b, a friction plate 75c disposed between the housing 77 and the cylindrical shaft 75b, and a pressing member 75d. The pressing member 75d is biased in a direction away from the friction plate 75c by a biasing member such as a spring (not shown). Inside the housing 77 on the forward clutch section 75 side, an oil passage 75e for supplying and discharging hydraulic oil is connected. When hydraulic oil is supplied from the oil passage 75e to the housing 77 side, the pressing member 75d moves toward the pressing side (connection side) against the biasing force of the spring, causing the friction plate 75c to press against the housing 77 side. As a result, the forward clutch section 75 enters the connected state, and the power of the input shaft 62f that rotates integrally with the composite output shaft 64 is transmitted to the gear 78a that rotates integrally with the cylindrical shaft 75b. The gear 78a is the output gear on the output side of the forward clutch section 75 and meshes with the input gear 80a. The input gear 80a is provided on the transmission shaft 66. When the gear 78a rotates, the input gear 80a rotates, and the transmission shaft 66 rotates integrally with the input gear 80a. Therefore, when the forward clutch section 75 is in the connected state, the low-speed range composite driving force from the planetary transmission section 60 is transmitted to the transmission shaft 66.

[0030] On the other hand, when hydraulic oil is discharged from the housing 77 side to the oil passage 75e, the pressing member 75d moves toward the disconnection side by the biasing force of the spring, causing the friction plate 75c to separate from the housing 77 side. As a result, the forward clutch section 75 enters the disconnected state, and the power of the input shaft 62f that rotates integrally with the composite output shaft 64 is not transmitted to the gear 78a. The reverse clutch section 76 includes a cylindrical shaft 76b, a friction plate 76c disposed between the housing 77 and the cylindrical shaft 76b, and a pressing member 76d. The pressing member 76d is biased in a direction away from the friction plate 76c by a biasing member such as a spring (not shown).

[0031] Inside the housing 77 on the reverse clutch section 76 side, an oil passage 76e for supplying and discharging hydraulic oil is connected. When hydraulic oil is supplied from the oil passage 76e to the housing 77 side, the pressing member 76d By moving toward the pressing side (connection side) against the biasing force of the spring, the friction plate 76c comes into pressure contact with the housing 77 side, the reverse clutch portion 76 enters a connected state, and the power of the input shaft 62f that rotates integrally with the combined output shaft 64 is transmitted to the gear 79 that rotates integrally with the cylindrical shaft 76b. The gear 79 is an output gear on the output side of the reverse clutch portion 76 and meshes with the reverse gear 79a. The reverse gear 79a meshes with the input gear 80b. The input gear 80b is provided on the transmission shaft 66. When the reverse gear 79a rotates, the input gear 80b rotates, and the transmission shaft 66 rotates integrally with the input gear 80b. Therefore, when the reverse clutch portion 76 is in the connected state, the low-speed range combined driving force from the planetary transmission portion 60 is transmitted to the transmission shaft 66 in reverse rotation.

[0032] On the other hand, when the hydraulic oil is discharged from the housing 77 side to the oil passage 76e, the pressing member 76d moves toward the disconnection side by the biasing force of the spring, the friction plate 76c separates from the housing 77 side, the reverse clutch portion 76 enters a disconnected state, and the power of the input shaft 62f that rotates integrally with the combined output shaft 64 is not transmitted to the gear 79. The sub-transmission mechanism 53 includes a transmission portion 95 provided between the first counter shaft 91 connected to the transmission shaft 66 and the rear wheel drive shaft 93, and transmission gears associated therewith. The sub-transmission mechanism 53 can perform two-stage shifting of the first speed (low speed stage) and the second speed (high speed stage). The shifting of the sub-transmission mechanism 53 is performed by a sub-shifting operation member 149 that can be switched to a plurality of positions. The sub-shifting operation member 149 is provided around the driver's seat 10 and is a lever that can be switched to three positions: a high speed position, a neutral position, and a low speed position. When the sub-shifting operation member 149 is in the neutral position, the power of the first counter shaft 91 is not transmitted to the rear wheel drive shaft 93, that is, the driving force of the prime mover 4 is not transmitted to the traveling device 7.

[0033] The rear-wheel drive shaft 93 shifted by the sub-transmission mechanism 53 is connected to a rear-wheel differential device 100 to which a rear axle 99 rotatably supporting the rear wheels 7R is connected, and the driving force of the forward transmission shaft 66 is transmitted to the traveling device 7 having the rear wheels 7R via the sub-transmission mechanism 53 and the rear-wheel drive shaft 93. Further, the driving force of the forward transmission shaft 66 is transmitted to the front-wheel transmission shaft 101 via the front wheels 59 98 provided on the rear-wheel drive shaft 93. A drive conversion clutch 102 for changing the rotation of the front wheels 7F or the like is provided on the front-wheel transmission shaft 101, and a front-wheel drive shaft 103 is connected to the output side of the drive conversion clutch 102. The front-wheel drive shaft 103 is connected to a front-wheel differential device 106 to which a front axle 105 rotatably supporting the front wheels 7F is connected, and the driving force of the forward transmission shaft 66 is transmitted to the traveling device 7 having the front wheels 7F via the sub-transmission mechanism 53 and the rear-wheel drive shaft 93. In the drive conversion clutch 102, the rotation of the front wheels 7F and the rear wheels 7R can be made constant speed, or it can be changed to 4WD in which both the front wheels 7F and the rear wheels 7R travel, or 2WD in which only the rear wheels 7R travel.

[0034] A PTO clutch device 110 is provided on the propeller shaft 54. The PTO clutch device 110 is composed of, for example, a hydraulic clutch or the like, and is switched between a state (connected state) in which the power of the propeller shaft 54 is transmitted to the PTO propeller shaft 111 and a state (disconnected state) in which the power of the propeller shaft 54 is not transmitted to the PTO propeller shaft 111 by engaging and disengaging the hydraulic clutch. A PTO transmission device 112 for changing the driving force (rotation) of the PTO propeller shaft 111 is provided in the middle of the PTO propeller shaft 111, and the rotation of the PTO propeller shaft 111, that is, the rotation of the PTO shaft 16 connected to the PTO propeller shaft 111 via a gear can be changed.

[0035] As shown in FIG. 1, the work vehicle 1 includes a braking device 140. The braking device 140 is a device for braking the traveling device 7. The braking device 140 has a braking operation member 141, a left braking device 142F, and a right braking device 142R. The braking operation member 141 is a member for performing a braking operation, and is a member that can be manually operated by a driver. The braking operation member 141 includes a left brake pedal 141F and a right brake pedal 141R. The left brake pedal 141F and the right brake pedal 141R are swingably supported by the vehicle body 3 or the like, provided near the driver's seat 10, and operable by the driver. The left braking device 142F and the right braking device 142R are disk-type braking devices, and can be switched between a braking state for braking and a released state for releasing the braking. The left braking device 142F is provided on the left side of the rear axle 99, and the right braking device 142R is provided on the right side of the rear axle 99.

[0036] When the driver operates (depresses) the left brake pedal 141F, the left connecting member 143F connected to the left brake pedal 141F moves in the braking direction, and the left braking device 142F can be brought into the braking state. When the driver operates (depresses) the right brake pedal 141R, the right connecting member 143R connected to the right brake pedal 141R moves in the braking direction, and the right braking device 142R can be brought into the braking state. Note that a connecting member for connecting the left brake pedal 141F and the right brake pedal 141R is detachably provided (a connected state in which it is hooked on the left brake pedal 141F and the right brake pedal 141R to connect the left brake pedal 141F and the right brake pedal 141R, and a non-connected state in which it is not hooked from the left brake pedal 141F and the right brake pedal 141R and is not connected). When the left brake pedal 141F and the right brake pedal 141R are connected by the connecting member, by depressing either the left brake pedal 141F or the right brake pedal 141R, the left braking device 142F and the right braking device 142R can be braked simultaneously, and by releasing the depression of either the left brake pedal 141F or the right brake pedal 141R, the braking of the left braking device 142F and the right braking device 142R can be released simultaneously.

[0037] Also, as shown in FIG. 1, the braking operation member 141 includes a parking brake 144. The parking brake 144 is, for example, a parking lever that is installed near the left brake pedal 141F and the right brake pedal 141R and is swingable. By operating the parking lever, the left brake pedal 141F and the right brake pedal 141R are locked by a link mechanism, and braking of the left braking device 142F and the right braking device 142R is performed.

[0038] The above-described parking brake 144 is not limited to the above-described mechanism. The parking brake 144 may be a mechanism that brakes by locking the rotation of a gear provided on the rear-wheel drive shaft 93 by operating an operating member. Alternatively, the parking brake 144 may be a mechanism that brakes by pressing against the disks (brake disks) of the left braking device 142F and the right braking device 142R by operating an operating member, or may be a mechanism that performs braking by electrically operating the left braking device 142F and the right braking device 142R. As shown in FIG. 2, the work vehicle 1 includes a control device 120 and a storage device (storage unit) 121. The control device 120 is composed of a CPU, an electric and electronic circuit, a program stored in the control device 120, and the like. The control device 120 performs various controls related to the work vehicle 1. The storage device 121 is composed of a non-volatile memory or the like.

[0039] The control device 120 is connected to a rotation sensor 146a that detects the rotational speed of the prime mover 4, a rotation sensor 146b that detects the rotational speed of the traveling motor M1, a rotation sensor 146c that detects the rotational speed of the combined output shaft 64 of the planetary transmission unit 60, and a vehicle speed sensor 146d that detects the speed of the vehicle body 3, i.e., the vehicle speed. Further, a speed instruction signal (a signal specifying the vehicle speed) from the main shift operation member 147, an instruction signal (a signal indicating the forward position F, the reverse position R, and the neutral position N) from the traveling operation member 148, and an instruction signal (a signal indicating the high speed position, the neutral position, and the low speed position) from the sub-shift operation member 149 are input to the control device 120. The main shift operation member 147 can have its operation position changed steplessly. The control device 120 adjusts the vehicle speed by performing angle control of the swash plate 56b of the hydraulic pump P1 and switching control of the first clutch device 52A and the forward clutch section 75 according to the operation position of the main shift operation member 147. Specifically, the control device 120 automatically switches between the high speed range (Hi) and the low speed range (Lo) of the clutch mechanism 52 according to the actual vehicle speed until the target vehicle speed determined by the operation position of the main shift operation member 147 is reached. As the operation amount of the main shift operation member 147 increases, the vehicle speed increases, and as the operation amount of the main shift operation member 147 decreases, the vehicle speed decreases. When the main shift operation member 147 is set to the high speed range, the vehicle speed can be set high, and when it is set to the low speed range, the vehicle speed can be set low.

[0040] The control device 120 performs vehicle speed control to operate the rotational speed of the traveling motor M1 so that the vehicle speed reaches the target vehicle speed (the vehicle speed corresponding to the forward target output value or the reverse target output value) obtained from the rotational speed detected by the rotation sensor 146c, the rotational speed detected by the vehicle speed sensor 146d, the instruction signal (a signal indicating the forward position F, the reverse position R, and the neutral position N) from the traveling operation member 148, the speed instruction signal (a signal specifying the vehicle speed) from the main shift operation member 147, the instruction signal (a signal indicating the high speed position, the neutral position, and the low speed position) from the sub-shift operation member 149, and based on the control map CM1. Thereby, the driver can change the vehicle speed to an arbitrary speed by operating the main shift operation member 147 to an arbitrary operation position.

[0041] The forward and reverse movements of the vehicle body 3 are performed by the traveling operation member 148. The traveling operation member 148 is a member that can be operated to a forward position F for moving the vehicle body 3 forward, a reverse position R for moving the vehicle body 3 backward, and a neutral position N (neutral) where the vehicle body 3 is not switched to either forward or backward. For example, the traveling operation member 148 is a lever (shuttle lever) or the like disposed in front of or on the side of the driver's seat 10. The shuttle lever is swingably supported in three stages (forward position F, reverse position R, neutral position N) on the console that rotatably supports the steering wheel 30. As described above, when the shuttle lever is switched to the forward position F, either the first clutch device 52A or the forward clutch portion 75 is in a connected state. When the shuttle lever is switched to the reverse position R, the reverse clutch portion 76 is in a connected state. When the shuttle lever is switched to the neutral position N, the first clutch device 52A and the second clutch device 52B (forward clutch portion 75, reverse clutch portion 76) are in a disconnected state. That is, the clutch mechanism 52 (first clutch device 52A, second clutch device 52B) switches the driving force shifted by the continuously variable transmission 50 based on the operations of the forward position F, reverse position R, and neutral position N of the traveling operation member 148.

[0042] A plurality of electromagnetic control valves 130 for operating the clutch mechanism 52 (first clutch device 52A, second clutch device 52B) are connected to the control device 120. The plurality of electromagnetic control valves 130 includes a first electromagnetic control valve 130a for operating the first clutch device 52A, a second electromagnetic control valve 130b for operating the forward clutch portion 75 of the second clutch device 52B, and a third electromagnetic control valve 130c for operating the reverse clutch portion 76 of the second clutch device 52B.

[0043] The first electromagnetic control valve 130a, the second electromagnetic control valve 130b, and the third electromagnetic control valve 130c each have a solenoid, and are valves whose opening degree changes according to the current excited in the solenoid. For the first electromagnetic control valve 130a, the second electromagnetic control valve 130b, and the third electromagnetic control valve 130c, the opening degree increases as the current excited in the solenoid increases, and the opening degree decreases as the current excited in the solenoid decreases. When the solenoids of the first electromagnetic control valve 130a, the second electromagnetic control valve 130b, and the third electromagnetic control valve 130c are demagnetized, that is, when no current is applied, the first electromagnetic control valve 130a, the second electromagnetic control valve 130b, and the third electromagnetic control valve 130c are all closed.

[0044] The first electromagnetic control valve 130a is connected to the oil passage 71e, the second electromagnetic control valve 130b is connected to the oil passage 75e, and the third electromagnetic control valve 130c is connected to the oil passage 76e. An oil passage 131 of a hydraulic pump P2 different from the hydraulic pump P1 is connected to the first electromagnetic control valve 130a, the second electromagnetic control valve 130b, and the third electromagnetic control valve 130c, and hydraulic oil can be supplied. An oil passage 132 for discharging the hydraulic oil is connected to the first electromagnetic control valve 130a, the second electromagnetic control valve 130b, and the third electromagnetic control valve 130c. For example, when in the fully closed state, the hydraulic oil is discharged from the output port.

[0045] When the control device 120 switches the clutch mechanism 52 (the first clutch device 52A, the second clutch device 52B), that is, when switching the combined driving force of the planetary transmission unit 60 to the low speed range or the high speed range, either one of the first clutch device 52A and the second clutch device 52B is set in the connected state and the other is set in the disconnected state. Specifically, when the operation position of the main shift operation member 147 is in the high-speed range and the traveling operation member 148 is in the forward position F, that is, when the vehicle body 3 is traveling forward (in the case of high-speed forward), the control device 120 outputs a current (control signal) to the solenoid of the first electromagnetic control valve 130a to fully open the first electromagnetic control valve 130a, thereby switching the first clutch device 52A from the disengaged state to the engaged state. Further, in the case of high-speed forward, the control device 120 demagnetizes the solenoids of the second electromagnetic control valve 130b and the third electromagnetic control valve 130c to fully close the second electromagnetic control valve 130b and the third electromagnetic control valve 130c, thereby setting the second clutch device 52B in the disengaged state (neutral state).

[0046] When the operation position of the main shift operation member 147 is in the low-speed range and the traveling operation member 148 is in the forward position F, that is, when the vehicle body 3 is traveling forward (in the case of low-speed forward), the solenoid of the first electromagnetic control valve 130a is demagnetized and the solenoid of the second electromagnetic control valve 130b is excited. As a result, the first electromagnetic control valve 130a is fully closed and the first clutch device 52A is in the disengaged state, and the second electromagnetic control valve 130b is fully open and the forward clutch portion 75 of the second clutch device 52B is in the engaged state.

[0047] When the operation position of the main shift operation member 147 is in the low-speed range and the traveling operation member 148 is in the reverse position R, that is, when the vehicle body 3 is traveling in the reverse direction (in the case of low-speed reverse), the solenoid of the first electromagnetic control valve 130a is demagnetized and the solenoid of the third electromagnetic control valve 130c is excited. As a result, the first electromagnetic control valve 130a is fully closed and the first clutch device 52A is in the disengaged state, and the third electromagnetic control valve 130c is fully open and the reverse clutch portion 76 of the second clutch device 52B is in the engaged state.

[0048] Now, although the vehicle was traveling at the vehicle speed specified by the main transmission operation member 147, there may be a braking start in which the vehicle body 3 is switched from a state in which the vehicle body 3 is braked (the brakes are applied but the vehicle has not completely stopped) to a traveling state. That is, in the braking start, with the left brake pedal 141F and the right brake pedal 141R being operated (the braking operation member 141 being operated), the traveling operation member 148 is switched from the neutral position N to either the forward position F or the reverse position R. In order to make the braking start smooth, the control device 120 changes the neutral target value, which is the driving force output from the continuously variable transmission 50 in a state where the traveling operation member 148 is previously held at the neutral position N, according to the operation amount of the braking operation member 141 (the operation amounts of the left brake pedal 141F and the right brake pedal 141R). For example, the control device 120 decreases the absolute value of the neutral target value as the operation amount (depression amount) increases, and increases the absolute value of the neutral target value as the operation amount (depression amount) decreases.

[0049] Hereinafter, the setting of the target value of the driving force output from the continuously variable transmission 50 (forward target value, reverse target value, neutral target value), braking start, etc. will be described in detail. The control device 120 includes a target calculation unit 120A and an output setting unit 120B. The target calculation unit 120A and the output setting unit 120B are composed of an electric and electronic circuit provided in the control device 120, a program stored in the control device 120, and the like.

[0050] The target calculation unit 120A calculates a forward target output value, which is the driving force output from the continuously variable transmission 50 when the traveling operation member 148 is switched from the neutral position N to the forward position F to move the vehicle body 3 forward, and a reverse target output value, which is the driving force output from the continuously variable transmission 50 when the traveling operation member 148 is switched from the neutral position N to the reverse position R to move the vehicle body 3 backward. The target calculation unit 120A obtains, for example, the forward target output value and the reverse target output value from a control map CM1 stored in the storage device 121. FIG. 3A shows an example of the control map CM1. As shown in FIG. 3A, the control map CM1 shows the relationship between the vehicle speed (travel speed) and the driving force output from the continuously variable transmission 50.

[0051] In a coordinate system where the first axis (X-axis: horizontal axis) indicating the traveling speed of the vehicle body (e.g., vehicle speed) and the second axis (Y-axis: vertical axis) indicating the driving force output from the continuously variable transmission 50 are orthogonal at the origin, the control map CM1 extends from a predetermined negative minimum value (-max) of the Y-axis (vertical axis) to the positive side of the X-axis and is inclined with respect to the Y-axis (vertical axis). The sub-shift mechanism 53 is engaged in the low speed stage, and the line L1 (first line) showing the relationship between the vehicle speed (horizontal axis) and the output value (vertical axis) of the continuously variable transmission 50 when the vehicle body 3 is moving forward at a first speed or less (low speed) (when the clutch 75 is connected), and the line L2 (second line) extending from the minimum value (-max) of the Y-axis (vertical axis) to the negative side of the X-axis and inclined with respect to the Y-axis at an inclination angle θ2 larger than the inclination angle θ1 of the line L1 when the vehicle body 3 is moving backward. Also, the control map CM1 further includes a line L3 (third line) extending from the minimum value (-max) of the Y-axis (vertical axis) to the positive side of the X-axis and inclined with respect to the Y-axis at an inclination angle θ3 larger than the inclination angle θ1 of the first line, showing the relationship between the vehicle speed (horizontal axis) and the output value (vertical axis) of the continuously variable transmission 50 when the sub-shift mechanism 53 is engaged in the low speed stage and the vehicle body 3 is moving forward at a second speed (high speed) higher than the first speed (when the clutch 52A is connected). That is, the control map CM1 includes the line L1 showing the relationship between the vehicle speed and the driving force of the continuously variable transmission 50 when the vehicle body 3 is moving forward at low speed, the line L2 showing the relationship between the vehicle speed and the driving force of the continuously variable transmission 50 when the vehicle body 3 is moving backward, and the line L3 showing the relationship between the vehicle speed and the driving force of the continuously variable transmission 50 when the vehicle body 3 is moving forward at high speed.

[0052] The inclination angle θ2 and the inclination angle θ3 are the same angle. For this reason, when the operation position of the main shift operation member 147 is in the high speed range (corresponding to Hi), whether the travel operation member 148 (shuttle lever) is in the reverse position R or the forward position F, the inclination angle of the swash plate 56b of the hydraulic pump P1 is the same, so there is no need to prepare the swash plate 56b in the intermediate position. In the control map CM1, the driving force during forward movement is represented by a plus sign, and the driving force during reverse movement is represented by a minus sign. The driving force output from the continuously variable transmission 50 is, for example, the rotational speed of the traveling motor M1, with the forward rotation side indicated by a plus sign and the reverse rotation side indicated by a minus sign. As shown in FIG. 2, the control device 120 controls the rotational speed of the traveling motor M1 by controlling the regulator 125 connected to the control device 120. Specifically, the regulator 125 includes a control valve (electromagnetic control valve) 126 such as a solenoid valve. The electromagnetic control valve 126 has a solenoid and is a valve whose opening degree changes according to the current excited in the solenoid. As the current excited in the solenoid increases, the opening degree of the electromagnetic control valve 126 increases, and as the current excited in the solenoid decreases, the opening degree of the electromagnetic control valve 126 decreases. When the solenoid of the electromagnetic control valve 126 is demagnetized, that is, when no current is applied, the electromagnetic control valve 126 is fully closed. By the electromagnetic control valve 126, the regulator 125 operates, and the angle of the swash plate 56b of the hydraulic pump P1 changes, so that the rotational speed of the traveling motor M1 can be changed by changing the flow rate or pressure of the hydraulic oil acting on the traveling motor M1.

[0053] Note that the driving force output from the continuously variable transmission 50, that is, the X-axis (horizontal axis) in the control map CM1 represents the vehicle speed, but instead, it may be represented by the rotational speed of the rear-wheel drive shaft 93 or the like, and is not limited to the vehicle speed. When the operation position of the main transmission operation member 147 is in the low speed range and the sub-transmission operation member 149 is in the low speed position, that is, when the vehicle body 3 is moved forward at a low speed (when the clutch 75 is connected), the target calculation unit 120A calculates the forward target output value based on the line L1 of the control map CM1. For example, when the vehicle speed of P11, that is, 40% of the maximum vehicle speed in the state where the gear of the sub-transmission mechanism 53 is in the low speed stage, the target calculation unit 120A sets the rotational speed V1 of the forward rotation of the traveling motor M1 as the forward target output value.

[0054] Further, for example, when the operation position of the main shift operation member 147 is in the high-speed range and the sub-shift operation member 149 is in the low-speed position, if the vehicle speed during forward movement of the vehicle body 3 is to be set to 100% (maximum value) (that is, the vehicle speed at P12), the target calculation unit 120A sets the rotational speed V2 of the reverse rotation of the traveling motor M1 as the forward target output value. That is, the target calculation unit 120A sets the rotation direction and rotational speed of the traveling motor M1 according to the vehicle speed (target vehicle speed) during forward movement.

[0055] Further, when the target calculation unit 120A reverses the vehicle body 3, it calculates a reverse target output value based on the line L2 of the control map CM1. For example, as shown at the time point P21, if the vehicle speed during reverse movement of the vehicle body 3 is to be set to 40% of the maximum vehicle speed during reverse movement, the target calculation unit 120A sets the rotational speed V11 of the reverse rotation of the traveling motor M1 as the reverse target output value. For example, if the vehicle speed during reverse movement of the vehicle body 3 is to be set to the maximum vehicle speed during reverse movement (100%: maximum value) (that is, the vehicle speed at P22), the target calculation unit 120A sets the rotational speed V2 of the forward rotation of the traveling motor M1 as the reverse target output value. That is, the target calculation unit 120A sets the rotation direction and rotational speed of the traveling motor M1 according to the vehicle speed (target vehicle speed) during reverse movement.

[0056] Now, in the present embodiment, not only during braking start but also during non-braking start, when the traveling operation member 148 (shuttle lever) is in the neutral position N, the swash plate 56b (HST swash plate) of the hydraulic pump P1 can be set to the intermediate position in advance. That is, even during non-braking start, when the traveling operation member 148 (shuttle lever) is in the neutral position N, always at the intersection of the line connecting the intersection of line L1 and line L4 corresponding to the target vehicle speed according to the operation position of the main shift operation member 147, line L2, and line L5, and the Y-axis, the hydraulic pump P Controls the inclined plate 56b (HST inclined plate) of 1. For this purpose, the output setting unit 120B sets a neutral target value based on the forward target output value and the reverse target output value. Here, in the control map CM1, when the target vehicle speed is P11 (= |P21|), when the traveling operation member 148 is switched from the neutral position N to the forward position F without operating the braking operation member 141 (when starting forward without braking), a line parallel to the vertical axis is defined as L4, and when the traveling operation member 148 is switched from the neutral position N to the reverse position R without operating the braking operation member 141 (when starting backward without braking), a line parallel to the vertical axis is defined as L5. The target calculation unit 120A sets the value V1 at which line L4 and line L1 intersect as the forward target output value (first target value), and sets the value V11 at which line L5 and line L2 intersect as the reverse target output value (second target value). The output setting unit 120B sets the value indicated by the position where the line L6 connecting the point J10 having the value of the forward target output value (first target value) V1 on line L1 and the point J11 having the value of the reverse target output value (second target value) V11 on line L2 intersects the vertical axis as the neutral target value V3.

[0057] On the other hand, when the output setting unit 120B operates the braking operation member 141 and switches from the neutral position N to the forward position F (when starting with braking), it sets a neutral target value based on the forward target output value and the reverse target output value. The output setting unit 120B sets the neutral target value based on line L4a, line L5a, line L1, and line L2, where line L4 and line L5 are shifted toward the side where the vehicle speed decreases according to the depression amount. When obtaining the neutral target value, the output setting unit 120B increases the shift amount ΔG of line L4a and line L5a. For example, when the depression amount is maximum, the output setting unit 120B shifts line L4a and line L5a until they coincide with the vertical axis (Y-axis). When the depression amount is minimum, the output setting unit 120B moves line L4a and line L5a until they coincide with line L4 and line L5. When the depression amount is 50%, each of line L4a and line L5a is positioned between the vertical axis (Y-axis) and line L4 and line L5.

[0058] The output setting unit 120B sets the value of the intersection point J3 between the line L7 connecting the first point J1, which is the intersection point of the line L1a obtained by extending the line L1 and the line L4a, and the second point J2, which is the intersection point of the line L2 and the line L5a, to the neutral target value. That is, the output setting unit 120B sets the value of the first point (forward target output value) at which the line L4a intersects the line L1a when the line L4a is translated in parallel according to the depression amount, and the value of the second point J2 at which the line L5a intersects the line L2 when the line L5a is translated in parallel according to the depression amount (reverse target output value) to the neutral target value. In this way, by changing the neutral target value according to the depression amount, the driving force of the continuously variable transmission 50 can reach the forward target output value and the reverse target output value as quickly as possible after the vehicle body 3 starts braking forward or after starting braking in reverse, reducing the shift shock while ensuring the filling time of the hydraulic oil to the clutch mechanism 52.

[0059] Note that when the control device 120 moves the vehicle body 3 forward at the second speed, that is, when controlling the vehicle speed using the line L3 of the control map CM1, the above neutral target value is not set. For example, when the main transmission operation member 147 is in the high speed range, the sub-transmission operation member 149 is in the low speed position, and the traveling operation member 148 is in the forward position F, the vehicle body 3 is moving forward at the second speed (high speed range speed) faster than the first speed (low speed range speed), and the above neutral target value is not set. The reason for not setting the neutral target value is due to the fact that the inclination angle θ2 and the inclination angle θ3 are the same angle. That is, when the operation position of the main transmission operation member 147 is in the high speed range (corresponding to Hi), whether the traveling operation member 148 (shuttle lever) is in the reverse position R or the forward position F, the inclination angle of the swash plate 56b of the hydraulic pump P1 is the same, so there is no need to prepare the swash plate 56b in the intermediate position.

[0060] Thus, the work vehicle 1 of the above embodiment includes a vehicle body 3 having a traveling device 7, a prime mover 4, a hydraulic pump P1 having a swash plate 56b that changes the output according to the swash plate angle, a traveling motor M1 having an output shaft 58 whose rotational speed changes according to the output of the hydraulic pump P1 and outputting the driving force of the output shaft 58, a continuously variable transmission 50, a planetary transmission unit 60 that outputs a combined driving force obtained by combining the driving force shifted by the continuously variable transmission 50 and the driving force from the prime mover 4, a forward position F for moving the vehicle body 3 forward, a reverse position R for moving the vehicle body 3 backward, a neutral position N for not switching the vehicle body 3 to either forward or backward, a travel operation member 148 that can be operated to these positions, and the travel operation member Based on the operations of the forward position F, reverse position R, and neutral position N of 148, a clutch mechanism 52 that switches the combined driving force output from the planetary transmission unit 60, and in a coordinate system where the first axis (X-axis: horizontal axis) indicating the traveling speed of the vehicle body 3 and the second axis (Y-axis: vertical axis) indicating the driving force output from the continuously variable transmission 50 are orthogonal at the origin, a line L1 that extends from a predetermined negative minimum value (-max) of the Y-axis (vertical axis) to the positive side of the X-axis and is inclined with respect to the Y-axis (vertical axis) when the vehicle body 3 is advanced at a first speed or less, and a line L2 that extends from the minimum value (-max) of the Y-axis (vertical axis) to the negative side of the X-axis and is inclined at an inclination angle θ2 larger than the inclination angle θ1 of the line L1 with respect to the Y-axis (vertical axis) when the vehicle body 3 is reversed, a storage device 121 that stores in advance a control map CM1 including the above, and a control device 120 that sets a neutral target value, which is the driving force output from the continuously variable transmission 50 when the traveling operation member 148 is held at the neutral position, based on the control map CM1. According to this configuration, when starting the vehicle body 3, based on the control map CM1, the neutral target value, which is the driving force output from the continuously variable transmission 50, is set using the line L1 in the low-speed forward range and the line L2 in reverse, so that the power transmitted to the traveling device 7 immediately after starting can be quickly made appropriate. Specifically, since a neutral target value smaller than the starting target output value is transmitted to the traveling device 7, the amount of change in the inclination angle of the swash plate 56b of the hydraulic pump P1 (that is, the amount of change in the HST output value) when the traveling operation member 148 (shuttle lever) is switched from the neutral position N to the forward position F or the reverse position R can be made smaller. For this reason, the shift shock can be mitigated and the overshoot due to the high-speed movement of the swash plate 56b can be reduced. Therefore, the shift shock at the time of starting can be mitigated and the traveling performance at the time of starting can be improved. Further, the control map CM1 includes the line L1 when the vehicle body 3 is advanced at a first speed or less and the line L2 when the vehicle body 3 is reversed, and since the inclination angle θ2 of the line L2 is larger than the inclination angle θ1 of the line L1, a suitable neutral target value can be set using the control map CM1.

[0061] The control map CM1 further includes a line L3 for advancing the vehicle body 3 at a second speed (speed in the high speed range) faster than the first speed (speed in the low speed range), which extends from the minimum negative value (-max) of the Y-axis (vertical axis) to the positive side of the X-axis (horizontal axis) and is inclined at an inclination angle θ3 greater than the inclination angle θ1 of the line L1 with respect to the Y-axis (vertical axis). According to this configuration, the vehicle body 3 can be advanced at the second speed (speed in the high speed range) using the line L3 of the control map CM1, which is different from the line L1 when advancing at the first speed (speed in the low speed range), and the running performance suitable for the second speed (speed in the high speed range) can be ensured.

[0062] When the control device 120 advances the vehicle body 3 at the first speed, it sets a neutral target value, which is the driving force output from the continuously variable transmission 50 when the travel operation member 148 is held at the neutral position N, based on the control map CM1. When the vehicle body 3 is advanced at the second speed, the neutral target value is not set. According to this configuration, when starting the vehicle body at the first speed (speed in the low speed range), since the neutral target value, which is the driving force output from the continuously variable transmission 50, is set based on the control map CM1, the power transmitted to the traveling device 7 immediately after starting at low speed can be made appropriate. That is, the shift shock during starting at low speed can be alleviated, etc., and the running performance during starting at low speed can be improved. On the other hand, when starting the vehicle body 3 at the second speed (speed in the high speed range), the neutral target value is not set. This is because since the line L3 (θ3) and the line L2 (θ2) are line-symmetrical during starting at high speed, there is no need for pre-control of the neutral target value. For this reason, since the forward target output value corresponding to the target speed is set without setting the neutral target value, the target speed can be reached quickly.

[0063] The work vehicle 1 includes a braking operation member 141 and a braking device 140 that brakes the traveling device 7 according to the operation of the braking operation member 141. The control device 120 changes a neutral target value, which is the driving force output from the continuously variable transmission 50 when the traveling operation member 148 is held at the neutral position N, according to the operation amount of the braking operation member 141. According to this configuration, when starting the work vehicle 1 from a braked state (in the case of starting with braking), since the neutral target value, which is the driving force output from the continuously variable transmission 50, can be changed according to the operation amount of the braking operation member 141, the power transmitted to the traveling device 7 immediately after starting with braking can be made more appropriate. That is, it is possible to reduce the shift shock during starting with braking and improve the running performance during starting with braking. It can be improved.

[0064] The control device 120 decreases the neutral target value as the operation amount increases and increases the neutral target value as the operation amount decreases. According to this configuration, during starting with braking, it is possible to make the transmission of power to the traveling device 7 as smooth as possible according to the operation amount of the braking operation member 141, that is, the braking force. The control device 120 has a target calculation unit 120A that calculates a forward target output value output from the continuously variable transmission 50 when the traveling operation member 148 is switched from the neutral position N to the forward position F to move the vehicle body 3 forward, and a reverse target output value output from the continuously variable transmission 50 when the traveling operation member 148 is switched from the neutral position N to the reverse position R to move the vehicle body 3 backward, and an output setting unit 120B that sets the neutral target value based on the operation amount of the braking operation member 141, the forward target output value, and the reverse target output value. According to this configuration, in the continuously variable transmission 50, it is possible to start from appropriate rotational speeds during forward and reverse travel, so it is possible to suppress a phenomenon in which the vehicle moves backward instantaneously during starting forward (that is, an instantaneous reverse movement (backward running) during starting with braking in the forward direction), and it is possible to suppress a phenomenon in which the vehicle moves forward instantaneously during starting in reverse (that is, an instantaneous reverse movement (backward running) during starting with braking in the reverse direction).

[0065] The output setting unit 120B sets a neutral target value based on a first target value that is the forward target output value when switching to the forward position F without operating the braking operation member 141, and a second target value that is the reverse target output value when switching to the reverse position R without operating the braking operation member 141. According to this configuration, the neutral target value can be set according to the balance between the forward target output value (first target value) and the reverse target output value (second target value), and the operation of the work vehicle 1 at the first forward movement when starting without braking and the operation of the work vehicle 1 at the first reverse movement can be stabilized.

[0066] The output setting unit 120B sets the intermediate value between the first target value and the second target value as the neutral target value. According to this configuration, the output of the continuously variable transmission 50 can be stabilized when starting by switching from the neutral position to the forward side and when starting by switching from the neutral position to the reverse side. That is, since the output of the continuously variable transmission 50 is set to the neutral target value and then set to the first target value or the second target value, the amount of change in the inclination angle of the swash plate 56b of the hydraulic pump P1 (that is, the amount of change in the HST output value) can be made smaller. Therefore, it is possible to reduce the shift shock and the overshoot due to the high-speed movement of the swash plate 56b.

[0067] The prime mover 4 outputs a driving force that is constant at a predetermined rotational speed, and the output setting unit 120B sets the rotational speed of the traveling motor M1 as the driving force output from the continuously variable transmission 50. According to this configuration, the degree of power transmission to the traveling device 7 can be easily adjusted by the rotational speed of the traveling motor M1. The clutch mechanism 52 includes a first clutch device 52A that can switch between a connected state in which the combined driving force of the planetary transmission unit 60 is transmitted to the forward side at the second speed (speed in the high-speed range) and a disconnected state in which it is not transmitted to the forward side, and a second clutch device 52B that can switch between a connected state in which the combined driving force of the planetary transmission unit 60 is transmitted to the forward side at the first speed (speed in the low-speed range), a connected state in which the combined driving force of the planetary transmission unit 60 is transmitted to the reverse side, and a disconnected state in which it is not transmitted to either the forward side or the reverse side. The control device 120 sets the second clutch device 52B to the disconnected state when setting the first clutch device 52A to the connected state, and sets the first clutch device 52A to the disconnected state when setting the second clutch device 52B to the connected state. According to this configuration, the continuously variable transmission device 50 and the planetary transmission unit 60 output driving forces at the first speed (speed in the low-speed range) and the second speed (speed in the high-speed range), and the first clutch device 52A switches to forward at the second speed, and the second clutch device 52B switches between forward and reverse at the first speed. In such a configuration, it is possible to reduce the shift shock during braking start and prevent momentary reverse movement (backward running) during braking start.

[0068] In the above embodiment, the case of braking start or non-braking start when the main shift operation member 147 is in the low-speed range or the high-speed range, the sub-shift operation member 149 is in the low-speed position, and the traveling operation member 148 is in the neutral position N has been described, but it is not limited thereto. For example, as shown in FIG. 3B, the case of braking start or non-braking start when the main shift operation member 147 is in the low-speed range or the high-speed range, the sub-shift operation member 149 is in the high-speed position, and the traveling operation member 148 is in the neutral position N is also applicable in the same manner as in the above embodiment.

[0069] The control map CM1 shown in FIG. 3B includes lines L11 to L13 in addition to lines L1 to L3. Line L11 extends from a predetermined negative minimum value (-max) of the Y-axis (vertical axis) to the positive side of the X-axis (horizontal axis) and is inclined at an inclination angle θ11 with respect to the Y-axis (vertical axis). The auxiliary transmission mechanism 53 is engaged in the high-speed stage, and when the vehicle body 3 is moving forward at a speed of the first speed or less (low speed) (when the clutch 75 is connected), it is a line (first line) showing the relationship between the vehicle speed (horizontal axis) and the output value (vertical axis) of the continuously variable transmission 50. Line L12 extends from the minimum value (-max) of the Y-axis (vertical axis) to the negative side of the X-axis (horizontal axis) and is inclined at an inclination angle θ12 greater than the inclination angle θ11 of line L11 with respect to the Y-axis (vertical axis). It is a line (second line) when the vehicle body 3 is moving backward. Line L13 extends from the minimum value (-max) of the Y-axis (vertical axis) to the positive side of the X-axis (horizontal axis) and is inclined at an inclination angle θ13 greater than the inclination angle θ11 of the first line with respect to the Y-axis (vertical axis). The auxiliary transmission mechanism 53 is engaged in the high-speed stage, and when the vehicle body 3 is moving forward at a second speed (high speed) faster than the first speed (when the clutch 52A is connected), it is a line (third line) showing the relationship between the vehicle speed (horizontal axis) and the output value (vertical axis) of the continuously variable transmission 50.

[0070] The inclination angle θ12 and the inclination angle θ13 are the same angle. Therefore, when the operation position of the main transmission operation member 147 is in the high-speed range (corresponding to Hi), whether the traveling operation member 148 (shuttle lever) is in the reverse position R or the forward position F, since the inclination angle of the swash plate 56b of the hydraulic pump P1 is the same, there is no need to prepare the swash plate 56b in the intermediate position. When the operation position of the main transmission operation member 147 is in the low-speed range and the auxiliary transmission operation member 149 is in the high-speed position, that is, when the vehicle body 3 is moving forward at a low speed (when the clutch 75 is connected), the target calculation unit 120A calculates the forward target output value based on line L11 of the control map CM1. For example, when the vehicle speed of P31, that is, 60% of the maximum vehicle speed in the state where the gear of the auxiliary transmission mechanism 53 is in the high-speed stage, the target calculation unit 120A sets the forward rotation speed V21 of the traveling motor M1 as the forward target output value.

[0071] Further, for example, when the operation position of the main shift operation member 147 is in the high-speed range and the sub-shift operation member 149 is in the high-speed position, and when the vehicle speed during forward movement of the vehicle body 3 is set to 100% (maximum value) (that is, the vehicle speed of P32), the target calculation unit 120A sets the rotation speed V22 of the reverse rotation of the traveling motor M1 as the forward target output value. That is, the target calculation unit 120A sets the rotation direction and rotation speed of the traveling motor M1 according to the vehicle speed (target vehicle speed) during forward movement.

[0072] Further, when the target calculation unit 120A reverses the vehicle body 3, it calculates a reverse target output value based on the line L12 of the control map CM1. For example, as shown at the time point P41, when the vehicle speed during reverse movement of the vehicle body 3 is set to 60% of the maximum vehicle speed during reverse movement, the target calculation unit 120A sets the rotation speed V31 of the reverse rotation of the traveling motor M1 as the reverse target output value. For example, when the vehicle speed during reverse movement of the vehicle body 3 is set to the maximum vehicle speed during reverse movement (100%: maximum value) (that is, the vehicle speed of P42), the target calculation unit 120A sets the rotation speed V22 of the forward rotation of the traveling motor M1 as the reverse target output value. That is, the target calculation unit 120A sets the rotation direction and rotation speed of the traveling motor M1 according to the vehicle speed (target vehicle speed) during reverse movement.

[0073] Now, in the present embodiment, not only during braking start but also during non-braking start, when the traveling operation member 148 (shuttle lever) is at the neutral position N, the swash plate 56b (HST swash plate) of the hydraulic pump P1 can be set to an intermediate position in advance. That is, even during non-braking start, when the traveling operation member 148 (shuttle lever) is at the neutral position N, the swash plate 56b (HST swash plate) of the hydraulic pump P1 is always controlled at the intersection of the line connecting the intersection of line L11 corresponding to the target vehicle speed corresponding to the operation position of the main transmission operation member 147 and line L14 and the intersection of line L12 and line L15 and the Y-axis. For this reason, the output setting unit 120B sets a neutral target value based on the forward target output value and the reverse target output value. Here, in the control map CM1, when the target vehicle speed is P31 (=|P41|), when the traveling operation member 148 is switched from the neutral position N to the forward position F without operating the braking operation member 141 (during non-braking start in the forward direction), the line parallel to the vertical axis is defined as L14, and when the traveling operation member 148 is switched from the neutral position N to the reverse position R without operating the braking operation member 141 (during non-braking start in the reverse direction), the line parallel to the vertical axis is defined as L15. In this case, the target calculation unit 120A sets the value V21 at which line L14 intersects line L11 as the forward target output value (first target value), and sets the value V31 at which line L15 intersects line L12 as the reverse target output value (second target value). The output setting unit 120B sets the value indicated by the intersection position of line L16 connecting point J30 where the value of the forward target output value (first target value) V21 is obtained on line L11 and point J31 where the value of the reverse target output value (second target value) V31 is obtained on line L12 and the vertical axis as the neutral target value V23.

[0074] On the other hand, when the output setting unit 120B switches from the neutral position N to the forward position F by operating the braking operation member 141 (when starting with braking), it sets a neutral target value based on the forward target output value and the reverse target output value. The output setting unit 120B sets the neutral target value based on lines L14a and L15a which are lines L14 and L15 shifted toward the lower vehicle speed side according to the depression amount, and lines L11 and L12. When obtaining the neutral target value, the output setting unit 120B increases the shift amount ΔG of lines L14a and L15a. For example, when the depression amount is maximum, the output setting unit 120B shifts lines L14a and L15a until they coincide with the vertical axis (Y-axis); when the depression amount is minimum, the output setting unit 120B moves lines L14a and L15a until they coincide with lines L14 and L15; when the depression amount is 50%, the output setting unit 120B positions lines L14a and L15a respectively between the vertical axis (Y-axis) and lines L14 and L15.

[0075] The output setting unit 120B sets the value of the intersection point J23 between the vertical axis (Y-axis) and line L17 that connects the first point J21 which is the intersection of line L11a (an extension of line L11) and line L14a, and the second point J22 which is the intersection of line L12 and line L15a, as the neutral target value. That is, the output setting unit 120B sets, as the neutral target value, an intermediate value that connects the value of the first point (forward target output value) where line L14a intersects line L11a when line L14a is translated parallel according to the depression amount, and the value of the second point J22 (reverse target output value) where line L15a intersects line L12 when line L15a is translated parallel according to the depression amount. By thus changing the neutral target value according to the depression amount, the driving force of the continuously variable transmission 50 can reach the forward target output value and the reverse target output value after forward braking start or reverse braking start of the vehicle body 3 as quickly as possible, reducing shift shock while ensuring the filling time of the hydraulic oil to the clutch mechanism 52.

[0076] Note that when the control device 120 moves the vehicle body 3 forward at the second speed, that is, when controlling the vehicle speed using the line L13 of the control map CM1, the above neutral target value is not set. For example, when the main transmission operation member 147 is in the high-speed range, the sub-transmission operation member 149 is in the high-speed position, and the traveling operation member 148 is in the forward position F, the vehicle body 3 is moving forward at the second speed (speed in the high-speed range) faster than the first speed (speed in the low-speed range), and the above neutral target value is not set. The reason for not setting the neutral target value is that the inclination angle θ12 and the inclination angle θ13 are the same angle. That is, when the operation position of the main transmission operation member 147 is in the high-speed range (corresponding to Hi), whether the traveling operation member 148 (shuttle lever) is in the reverse position R or the forward position F, the inclination angle of the swash plate 56b of the hydraulic pump P1 is the same, so there is no need to prepare the swash plate 56b in the intermediate position.

[0077] Next, the switching between the warm-up operation mode and the traveling operation mode will be described. The control device 120 can be switched between the warm-up operation mode and the traveling operation mode. The warm-up operation mode and the traveling operation mode can be switched automatically or manually. The warm-up operation mode is a mode in which the gears of the transmission 5 are rotated in a state where the transmission of power from the transmission 5 to the traveling device 7 is blocked. The traveling operation mode is a mode in which the gears are rotated in a state where the power is transmitted from the transmission 5 to the traveling device 7. That is, in the traveling operation mode, it is a mode in which the vehicle body 3 can be driven by manual operation by the driver or automatic operation by the control device 120, and usually, the transmission 5 (continuously variable transmission 50, planetary transmission unit 60, clutch mechanism 52, and sub-transmission mechanism 53) is operated to perform gear shifting.

[0078] Specifically, a temperature measuring device 150 capable of measuring the temperature of the lubricating oil is connected to the control device 120. This continues. When the ignition switch or the like changes from OFF to ON and the prime mover 4 is driven (the output shaft (crankshaft) 4a of the prime mover 4 rotates), the control device 120 refers to the temperature (lubricating oil temperature) detected by the temperature measuring device 150. When the lubricating oil temperature is, for example, less than -15°C, that is, less than the threshold value and the viscosity of the lubricating oil is high (Condition 1), the control device 120 automatically switches to the warm-up operation mode. On the other hand, when the lubricating oil temperature is -15°C or higher (threshold value or higher) and the viscosity of the lubricating oil is low, the control device 120 switches to the traveling operation mode. Note that the threshold value for determining the lubricating oil temperature is an example and is not limited to the above-described temperature.

[0079] Alternatively, when the sub-shift operation member 149 is in the neutral position and the parking brake 144 of the brake operation member 141 is ON (the state in which the traveling device 7 is being braked by the brake device 140) (Condition 2), the control device 120 automatically switches to the warm-up operation mode. Note that when the sub-shift operation member 149 is in the neutral position, the parking brake 144 of the brake operation member 141 is ON, and the traveling operation member 148 is in the neutral position N (Condition 3), the control device 120 may automatically switch to the warm-up operation mode. Alternatively, when the parking brake 144 of the brake operation member 141 is ON and the traveling operation member 148 is in the neutral position N (Condition 4), the control device 120 may automatically switch to the warm-up operation mode.

[0080] When the control device 120 satisfies Condition 1 and Condition 2, it may automatically switch to the warm-up operation mode, or when it satisfies Condition 1 and Condition 3, it may automatically switch to the warm-up operation mode, or when it satisfies Condition 1 and Condition 4, it may automatically switch to the warm-up operation mode. When any of Condition 2, Condition 3, and Condition 4 is not met while Condition 1 is satisfied, the condition is displayed on a display device provided in the work vehicle 1, for example, a meter panel, and the driver is prompted to adjust the condition.

[0081] When the control device 120 switches to the warm-up operation mode, for example, it rotates the planetary transmission unit 60 (such as the input gear 62 and the planetary gear mechanism 63) by switching the first clutch device 52A from the disengaged state to the engaged state and holding the second clutch device 52B in the disengaged state. Alternatively, when the control device 120 switches to the warm-up operation mode, it rotates the planetary transmission unit 60 (such as the carrier 63a, the input gear 62, and the planetary gear mechanism 63) by switching the second clutch device 52B from the disengaged state to the engaged state while holding the first clutch device 52A in the engaged state. For example, when in the warm-up operation mode, the control device 120 sets the forward clutch unit 75 in the engaged state and the reverse clutch unit 76 in the disengaged state, or sets the forward clutch unit 75 in the disengaged state and the reverse clutch unit 76 in the engaged state. Note that when in the warm-up operation mode, the control device 120 sets a lower limit value for the rotational speed of the prime mover 4 (prime mover rotational speed) so that the prime mover rotational speed does not fall below the lower limit value.

[0082] After the control device 120 switches to the warm-up operation mode, it may automatically switch to the driving operation mode when referring to the lubricating oil temperature detected by the temperature measuring device 150 and the lubricating oil temperature is -15°C or higher. Alternatively, after the control device 120 switches to the warm-up operation mode and operates the planetary transmission unit 60 in the warm-up operation mode, it may switch to the driving operation mode when a predetermined time has elapsed.

[0083] In the above-described embodiment, the control device 120 automatically switches to the warm-up operation mode, but the driver may manually switch to the warm-up operation mode. A switching device 155 capable of manually switching between the warm-up operation mode and the traveling operation mode is connected to the control device 120. The switching device 155 is provided around the driver's seat 10 and is a switch that can be switched between ON and OFF. When the switching device 155 is ON (condition 5), the control device 120 switches to the warm-up operation mode, and when the switching device 155 is OFF, the control device 120 switches to the traveling operation mode. When manually switching the control device 120 to the warm-up operation mode, it may switch to the warm-up operation mode when conditions 5 and 2 are satisfied, or it may switch to the warm-up operation mode when conditions 5 and 3 are satisfied, or it may switch to the warm-up operation mode when conditions 5 and 4 are satisfied. When the work vehicle 1 is operating in the warm-up operation mode when the switching device 155 is manually switched from ON to OFF, the warm-up operation mode may be forcibly stopped and switched to the traveling operation mode.

[0084] FIGS. 5A and 5B show an example of the operation flow of the control device 120. As shown in FIG. 5A, when the driving of the prime mover 4 is started, the control device 120 is first set to the traveling operation mode (S1). The control device 120 determines whether the switching conditions for the warm-up operation mode (condition 1 and condition 2, condition 1 and condition 3) are satisfied (S2). If the switching conditions for the warm-up operation mode are satisfied (S2, Yes), it automatically switches from the traveling operation mode to the warm-up operation mode (S3). When switching to the warm-up operation mode, the control device 120 rotates the planetary transmission unit 60 (input gear 62, planetary gear mechanism 63, etc.) by, for example, bringing either the first clutch device 52A or the second clutch device 52B into a connected state (S4). When the lubricating oil temperature is equal to or higher than the threshold value or the elapsed time since the warm-up operation mode was executed is equal to or longer than a predetermined time (S5, Yes), the control device 120 switches from the warm-up operation mode to the traveling operation mode (S6). When the lubricating oil temperature is lower than the threshold value or the elapsed time since the warm-up operation mode was executed is less than a predetermined time (S5, No), the control device 120 continues the warm-up operation mode. During the continuation of the warm-up operation mode, if the switching device 155 is switched to OFF after being switched to ON, it is forcibly switched to the warm-up operation mode.

[0085] As shown in FIG. 5B, when the driving of the prime mover 4 is started, the control device 120 first sets the traveling operation mode (S1). The control device 120 determines whether the switching conditions for the warm-up operation mode (condition 5 and condition 2, condition 5 and condition 3, condition 5 and condition 4) are satisfied (S11). When the switching conditions for the warm-up operation mode are satisfied (S11, Yes), the mode is manually switched from the traveling operation mode to the warm-up operation mode (S12). When the mode is switched to the warm-up operation mode, the control device 120 rotates the planetary transmission unit 60 (input gear 62, planetary gear mechanism 63, etc.) by, for example, connecting either the first clutch device 52A or the second clutch device 52B (S13). When the lubricating oil temperature is equal to or higher than the threshold value or the elapsed time since the warm-up operation mode was executed is equal to or longer than a predetermined time (S14, Yes), the control device 120 switches from the warm-up operation mode to the traveling operation mode (S15). When the lubricating oil temperature is lower than the threshold value or the elapsed time since the warm-up operation mode was executed is shorter than a predetermined time (S14, No), the control device 120 continues the warm-up operation mode. During the continuation of the warm-up operation mode, if the switching device 155 is turned on and then turned off, the warm-up operation mode is forced.

[0086] The work vehicle 1 includes a vehicle body 3 provided with a traveling device 7, a prime mover 4 provided on the vehicle body 3, a transmission 5 capable of changing the driving force from the prime mover 4 and transmitting it to the traveling device 7, a transmission case 12 that houses the transmission 5 and is filled with lubricating oil, a warm-up operation mode for rotating the gears of the transmission 5 in a state where the power transmission from the transmission 5 to the traveling device 7 is blocked, and a control device 120 capable of switching between a traveling operation mode for rotating the gears in a state where the power is transmitted from the transmission 5 to the traveling device 7. According to this, when in the traveling operation mode, traveling can be performed by rotating the gears of the transmission 5, while when in the warm-up operation mode, the temperature of the lubricating oil in the transmission 5 can be quickly increased by rotating the gears of the transmission 5, and warm-up can be efficiently performed. That is, the temperature of the lubricating oil can be increased by the rotation of the gears of the transmission 5.

[0087] The work vehicle 1 is provided with a temperature measuring device 150 capable of measuring the temperature of the lubricating oil. When the temperature measured by the temperature measuring device 150 is less than the threshold value, the control device 120 switches to the warm-up operation mode, and when the temperature is equal to or higher than the threshold value, it switches to the traveling operation mode. According to this, when the temperature of the lubricating oil is low and the viscosity is high, the warm-up operation can be automatically performed, and when the temperature of the lubricating oil is high and the viscosity is low, it can be switched to traveling.

[0088] The control device 120 switches to the traveling operation mode after a predetermined time has elapsed since rotating the gear in the warm-up operation mode. According to this, the warm-up operation can be performed for a predetermined time, and after the warm-up operation, it is possible to switch to the traveling operation mode and perform work while traveling. The work vehicle 1 is provided with a switching device 155 that can manually switch between the warm-up operation mode and the traveling operation mode. According to this, when warming up is necessary or traveling is necessary, etc., by the driver or the like, warming up and traveling can be performed as intended by the driver.

[0089] The work vehicle 1 is provided with a braking device 140 that brakes the traveling device 7. The transmission 5 has a sub-transmission mechanism 53 capable of changing the driving force from the prime mover 4 in multiple stages. The control device 120 switches to the warm-up operation mode in a neutral state where the sub-transmission mechanism 53 does not shift gears and in a state where the traveling device 7 is braked by the braking device 140. According to this, on the condition that power is not transmitted to the traveling device 7 by the sub-transmission mechanism 53 and braking is being performed, the warm-up operation can be performed with the work vehicle 1 properly stopped.

[0090] The work vehicle 1 is provided with a braking operation member 141 that operates the braking of the braking device 140 and a sub-transmission operation member 149 that can switch the sub-transmission mechanism 53 to the neutral state. According to this, by the operation of the braking operation member 141 and the sub-transmission operation member 149 by the driver, the work vehicle 1 can be surely made immobile. When in the warm-up operation mode, the control device 120 connects either the first clutch device 52A or the second clutch device 52B. According to this, by connecting either the first clutch device 52A or the second clutch device 52B, the planetary transmission unit 60 (such as the input gear 62, planetary gear mechanism 63, etc.) can be operated during the warm-up operation, and the warm-up can be completed in a shorter time.

[0091] In addition, when performing the warm-up operation, it is applicable to the work vehicle 1 in which the power to the traveling device 7 etc. is cut off (it only needs to be cut off) and can be set to the neutral state by the shuttle lever. In this case, the warm-up operation can be performed even on a slope or the like. Further, the control device 120 may be switched to the warm-up operation mode when the power to the traveling device 7 etc. is cut off, and can be set to the warm-up operation mode even in a state where braking is not being performed. In this case, when the control device 120 executes warm-up in the warm-up operation mode, the left brake device 142F and the right brake device 142R are operated to bring them into a braking state.

[0092] It should be considered that all aspects of the embodiments disclosed this time are illustrative and not restrictive. 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 equivalent to the claims are included.

Explanation of Reference Numerals

[0093] 1: Work vehicle 3: Vehicle body 4: Prime mover 5: Transmission 7: Traveling device 50: Continuously variable transmission 52: Clutch mechanism 52A: First clutch device 52B: Second clutch device 56b: Swash plate 60: Planetary transmission unit 120: Control device 120A: Target calculation unit 120B: Output setting unit 121: Memory device 140: Braking device 141: Braking operation member 148: Travel operation member CM1: Control map F: Forward position L1: Line (first line) L2: Line (second line) L3: Line (third line) M1: Travel motor N: Neutral position P1: Hydraulic pump R: Reverse position V1: Rotation speed V11: Rotation speed V2: Rotation speed V3: Neutral target value

Claims

1. A vehicle body having a running device; The prime mover, a continuously variable transmission including a hydraulic pump having a swash plate whose output is changed according to the swash plate angle, and a travel motor having an output shaft whose rotation speed is changed according to the output of the hydraulic pump and which outputs a driving force of the output shaft; a planetary transmission unit that outputs a combined driving force obtained by combining the driving force changed in speed by the continuously variable transmission device and the driving force from the prime mover; a travel operating member operable to a forward position for moving the vehicle body forward, a reverse position for moving the vehicle body backward, and a neutral position for switching the vehicle body neither forward nor reverse; a clutch mechanism that switches a combined driving force output from the planetary transmission unit based on an operation of the travel operating member between a forward position, a reverse position, and a neutral position; a storage device that prestores a control map including, in a coordinate system in which a first axis indicating the traveling speed of the vehicle body and a second axis indicating the driving force output from the continuously variable transmission device are orthogonal to each other at an origin, a first line when the vehicle body is moved forward at a first speed or less, the first line extending from a predetermined negative minimum value of the second axis to the positive side of the first axis and inclined with respect to the second axis, and a second line when the vehicle body is moved backward, the second line extending from the minimum value of the second axis to the negative side of the first axis and inclined with respect to the second axis at an inclination angle larger than the inclination angle of the first line; a control device that sets a neutral target value, which is a driving force output from the continuously variable transmission when the traveling operation member is held in the neutral position, based on the control map; Equipped with the control map further includes a third line, which extends from the minimum value of the second axis to a positive side of the first axis and is inclined with respect to the second axis at an inclination angle larger than an inclination angle of the first line, when the vehicle body is moved forward at a second speed faster than the first speed; The control device sets a neutral target value, which is the driving force output from the continuously variable transmission when the travel operating member is held in the neutral position, based on the control map when the vehicle body is moved forward at the first speed, and does not set the neutral target value when the vehicle body is moved forward at the second speed.

2. A brake operating member; a braking device that applies a brake to the traveling device in response to an operation of the brake operating member, 2. The work vehicle according to claim 1, wherein the control device changes a neutral target value, which is the driving force output from the continuously variable transmission when the travel operating member is held in the neutral position, in accordance with an operation amount of the brake operating member.

3. The work vehicle according to claim 2 , wherein the control device decreases the neutral target value as the operation amount increases, and increases the neutral target value as the operation amount decreases.

4. The control device includes: a target calculation unit that calculates a forward target output value to be output from the continuously variable transmission when the traveling operation member is switched from a neutral position to a forward position to move the vehicle body forward, and a reverse target output value to be output from the continuously variable transmission when the traveling operation member is switched from the neutral position to a reverse position to move the vehicle body backward; an output setting unit that sets the neutral target value based on the operation amount of the brake operating member, the forward target output value, and the reverse target output value; 4. A work vehicle according to claim 2 or 3, comprising:

5. Equipped with a brake operating member, The control device includes: a target calculation unit that calculates a forward target output value to be output from the continuously variable transmission when the traveling operation member is switched from a neutral position to a forward position to move the vehicle body forward, and a reverse target output value to be output from the continuously variable transmission when the traveling operation member is switched from the neutral position to a reverse position to move the vehicle body backward; an output setting unit that sets a neutral target value based on a first target value that is a forward drive target output value when the vehicle is switched to the forward position without operating the brake operating member, and a second target value that is a reverse drive target output value when the vehicle is switched to the reverse position without operating the brake operating member; The work vehicle according to claim 1 .

6. The work vehicle according to claim 5 , wherein the output setting unit sets an intermediate value between the first target value and the second target value as the neutral target value.

7. The prime mover outputs a constant driving force at a predetermined rotation speed, 7. The work vehicle according to claim 4, wherein the output setting unit sets the rotation speed of the travel motor as the driving force output from the continuously variable transmission.

8. the clutch mechanism is a first clutch device switchable between a connected state in which the combined driving force of the planetary transmission parts is transmitted to the forward drive side at the second speed and a disconnected state in which the combined driving force of the planetary transmission parts is not transmitted to the forward drive side; a second clutch device switchable between a connected state in which a combined driving force of the planetary transmission unit is transmitted to a forward side at the first speed, a connected state in which the combined driving force of the planetary transmission unit is transmitted to a reverse side, and a disconnected state in which the combined driving force of the planetary transmission unit is not transmitted to either the forward side or the reverse side, 2. The work vehicle according to claim 1, wherein the control device sets the second clutch device in a disengaged state when the first clutch device is in an engaged state, and sets the first clutch device in a disengaged state when the second clutch device is in an engaged state.

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