JP2007091090A - Travel controlling device for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel controlling device for a working vehicle by which a linear traveling and a turning traveling can be favorably performed, and in addition, a good linear traveling can be performed when a large travel driving force is temporarily required at the time of the linear traveling. <P>SOLUTION: When a command for the linear traveling is received, the output of an infinite variable speed drive 7 for linear traveling is respectively transmitted to a pair of right and left traveling devices 1R and 1L. When a command for a right turning is received, the output of the infinite variable speed drive 7 for linear traveling is transmitted to the traveling device 1L on the left side, and also, the output of an infinite variable speed drive 8 is transmitted to the traveling device 1R on the right side. When a command for a left turning is received, the output of the infinite variable speed drive 7 for linear traveling is transmitted to the traveling device 1R on the right side, and also, the output of the infinite variable speed drive 8 for turning is transmitted to the traveling device 1L on the left side. When a command for increasing the travel driving force is received, the output of the infinite variable speed drive 7 for linear traveling and the output of the infinite variable speed drive 8 for turning are respectively transmitted to the pair of the right and left traveling devices 1R and 1L. Then, the infinite variable speed drive 8 for turning is controlled to have the same or approximately the same speed as the infinite variable speed drive 7 for linear traveling. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a linear transmission state in which a shift output of a continuously variable continuously variable transmission is transmitted to each of a pair of left and right traveling devices, a transmission output of the continuously variable continuously variable transmission is transmitted to a right traveling device, and A left turn transmission state in which the shift output of the continuously variable transmission for turning is transmitted to the left traveling device, and the shift output of the continuously variable continuously variable transmission is transmitted to the left traveling device and is used for the turning. Transmission state switching means capable of switching to a right-turning transmission state for transmitting the shift output of the continuously variable transmission to the right traveling device, an actuator for shifting the turning continuously variable transmission, and the linear drive Manual operation type shifting operation tool for shifting the continuously variable transmission by manual operation, turn command means for commanding straight, right turn and left turn, operation of the transmission state switching means and the actuator And control means to control When the control means is instructed to go straight by the turning command means, the control means controls to switch the transmission state switching means to the transmission state for straight movement, and a right turn is instructed by the turning command means. Then, the transmission state switching means is switched to the right turning transmission state to control the operation of the actuator so that the turning continuously variable transmission has a turning target speed, and the turning command When the left turn is commanded by the means, the transmission state switching means is switched to the left turn transmission state, and the operation of the actuator is controlled so that the turning continuously variable transmission has the turning target speed. The present invention relates to a traveling control device for a work vehicle configured to do this.

  When traveling in a straight traveling state, the traveling control device for a work vehicle having the above-described configuration shifts the shift output of the continuously variable continuously variable transmission that is shifted according to the operation of the manually operated shift operation tool. By transmitting to each of the pair of traveling devices, the left and right traveling devices are driven at the same speed, so that the vehicle body can travel straight ahead appropriately, and when performing a turn traveling, The traveling device located on the turning side is driven by a continuously variable transmission for turning, the traveling device located on the opposite side is driven by a continuously variable transmission for straight travel, and the operation of the actuator By changing the speed ratio between the continuously variable transmission for straight travel and the continuously variable transmission for turning, it is possible to smoothly make a turn by a desired turning state due to the speed difference between the pair of left and right traveling devices. Those were Unishi but the travel control device of such a work vehicle, conventionally, as applied to combine as an example of a work vehicle, there is one configured as follows.

  That is, when a straight travel is commanded by the turn command means and the transmission state switching means is switched to the straight travel transmission state, the shift output of the continuously variable continuously variable transmission is transmitted to each of the pair of left and right traveling devices. The transmission output of the continuously variable transmission for turning is cut off from the pair of left and right traveling devices. In other words, the pair of left and right traveling devices are driven at the same speed by the traveling driving force of only the continuously variable transmission for straight travel (see, for example, Patent Document 1).

JP 2005-247154 A

  By the way, a combine, which is an example of a work vehicle, is a work for cutting planted stems in a field or the like, and after finishing the work, it is necessary to get over the fence from the inside of the field and escape to the outside of the field or on the road. In some cases, a large driving force may be required temporarily, such as when riding on the platform of a driving vehicle using a walking board, or when the traveling device is buried in mud and is idle. In such a case, if the driving force is insufficient, the vehicle may not be able to perform good straight traveling.

  In the above-mentioned conventional configuration, when traveling straight, it is possible to properly travel straight by driving the pair of left and right traveling devices at the same speed by a continuously variable transmission for straight travel, A pair of left and right traveling devices are driven separately by a continuously variable transmission for straight travel and a continuously variable transmission for turning, and smoothly turn in a desired turning state due to the speed difference between the continuously variable transmissions. However, when a large driving force is temporarily required as described above, the driving force of the continuously variable continuously variable transmission is insufficient. In some cases, there is a risk that good straight traveling cannot be performed.

  An object of the present invention is to provide a travel drive that is temporarily large during straight travel while having the advantage of being able to appropriately perform straight travel and having a smooth turn in a desired turning state. The present invention is to provide a traveling control device for a work vehicle that can solve a shortage of driving force and perform excellent straight traveling when force is required.

  The traveling control device for a work vehicle according to the present invention includes a straight transmission state in which a shift output of a continuously variable continuously variable transmission is transmitted to each of a pair of left and right traveling devices, and a shift output of the continuously variable continuously variable transmission. A left-turn transmission state in which the shift output of the continuously variable transmission for turning is transmitted to the left travel device, and the shift output of the continuously variable continuously variable transmission is transmitted to the left travel device. Transmission state switching means that can be switched to a right-turning transmission state that transmits to the right traveling device, and shift operation of the turning continuously-variable transmission device. An actuator that performs manual operation, and a turn command means that commands straight, right turn, and left turn, and the transmission. The state switching means and the actuator And a control means for controlling the transmission state switching means to switch to the linear transmission state when the straight command is commanded by the turning command means, and the turning command means. When the right turn is commanded at, the transmission state switching means is switched to the right turn transmission state and the actuator is operated so that the turning continuously variable transmission has the turning target speed. When the left turn is commanded by the turn command means, the transmission state switching means is switched to the left turn transmission state, and the continuously variable transmission for turning becomes the target speed for turning. The first characteristic configuration is provided with a driving force increase command means for commanding an increase in traveling driving force, and the transmission state switching means is configured to control the operation of the actuator. ,in front A straight drive that transmits a shift output of the continuously variable continuously variable transmission device to each of the pair of left and right traveling devices, and transmits a shift output of the continuously variable transmission device for turning to each of the pair of left and right traveling devices. When the control means is instructed to increase the travel driving force by the driving force increase command means in a state where the control means is instructed to go straight by the turning command means. The transmission state switching means is switched to the transmission state for increasing the driving force, and the turning continuously variable transmission is the same as or substantially the same speed as the linearly variable continuously variable transmission. The driving power increasing type straight traveling control for controlling the operation is executed.

  According to the first characteristic configuration, when the driving force increase commanding unit is instructed to increase the traveling driving force in a state in which the turning commanding unit is instructed to go straight, the control unit is configured to transmit the transmission state switching unit. Is switched to the transmission state for increasing the driving force. In other words, the shift output of the continuously variable continuously variable transmission is transmitted to each of the pair of left and right traveling devices, and the shift output of the continuously variable transmission for turning is transmitted to each of the pair of left and right traveling devices. It is done. Then, the control means controls the operation of the actuator so that the turning continuously variable transmission has the same or substantially the same speed as the linearly variable continuously variable transmission.

  In other words, since the respective shift outputs of the continuously variable transmission for straight travel and the continuously variable transmission for turning are transmitted to each of the pair of left and right traveling devices, there is no linear motion for the pair of left and right traveling devices. In addition to the shift output of the step transmission, the shift output of the continuously variable transmission for turning is also transmitted.

  As a result, it is possible to drive a pair of left and right traveling devices with a large traveling driving force compared to those driven by only the speed change output of the continuously variable transmission for straight travel, for example, over the fence from inside the field. Thus, even when a large driving force is temporarily required, such as when escaping to the outside of the field, good straight traveling can be performed. In other words, the shift output of the continuously variable transmission for straight travel and the shift output of the continuously variable transmission for turning are transmitted to the pair of left and right traveling devices, so that the pair of left and right traveling devices can be reliably transmitted at the same speed. It will be driven and good straight running can be performed.

  By the way, the linearly variable continuously variable transmission and the continuously variable continuously variable transmission are caused by individual differences between the continuously variable transmissions even if the operation of the actuator is controlled so that they have the same speed. In many cases, they do not have exactly the same rotational speed, and when the above-mentioned driving force increase type straight traveling control is executed, the difference in speed of each continuously variable transmission is caused by friction between members in the transmission mechanism. However, it is not preferable in terms of durability to continue such a transmission state for a long time, but in the case where a large driving force is temporarily required as described above, a short time is required. It is only possible to perform.

  Further, when the driving force increase command means is not instructed to increase the driving force, during straight traveling, the left and right traveling devices are driven at the same speed by the continuously variable transmission for straight traveling. In addition, at the time of turning, the pair of left and right traveling devices are separately driven by the continuously variable transmission for straight movement and the continuously variable transmission for turning, respectively. Thus, the vehicle can smoothly turn in a desired turning state due to the speed difference.

  Therefore, it is possible to appropriately perform straight traveling and to smoothly perform turning according to a desired turning state, but temporarily requires a large driving force during straight traveling. In such a case, it has become possible to provide a travel control device for a work vehicle that can solve the shortage of driving force and perform good straight traveling.

  A second characteristic configuration of the present invention is a linear transmission state in which a shift output of a continuously variable continuously variable transmission is transmitted to each of a pair of left and right traveling devices, and a shift output of the continuously variable continuously variable transmission is driven to the right. A transmission state for left-turn transmission in which the transmission output of the continuously variable transmission for turning is transmitted to the left traveling device, and a transmission output of the continuously variable transmission for straight travel is transmitted to the left traveling device. And a transmission state switching means capable of switching to a right turning transmission state for transmitting a shift output of the turning continuously variable transmission to a right traveling device, and an actuator for shifting the turning continuously variable transmission. A manually operated speed change operation tool for manually shifting the linearly variable continuously variable transmission, a turn command means for commanding straight, right turn, and left turn, and the transmission state switching means. And controlling the operation of the actuator And a control means for controlling the transmission state switching means to switch to the straight transmission state when the turning command means is commanded to go straight, and the turning command means When turning is commanded, the transmission state switching means is switched to the right turning transmission state, and the operation of the actuator is controlled so that the turning continuously variable transmission has a turning target speed, Further, when a left turn is commanded by the turning command means, the transmission state switching means is switched to the left turning transmission state so that the continuously variable transmission for turning becomes the target speed for turning. A travel control device for a work vehicle configured to control the operation of an actuator, comprising drive force increase command means for commanding increase of travel drive force, wherein the transmission state switching means is for the straight travel Invariant A transmission for transmitting straight speed is transmitted to one of a pair of left and right traveling devices, and a transmission output of the continuously variable transmission for turning is transmitted to the other of the pair of left and right traveling devices. It is configured to be switchable to a driving force increasing transmission state, and when the control means is commanded to increase the driving force by the driving force increasing command means in a state in which straight movement is commanded by the turning command means. The transmission state switching means is switched to the linear drive driving force increasing transmission state, and the turning continuously variable transmission is the same or substantially the same speed as the linearly variable continuously variable transmission. The driving power increasing type straight traveling control for controlling the operation of the actuator is executed.

  According to the second characteristic configuration, in the state in which the rectilinear command is commanded by the turning command means, if the driving force increase command means is commanded to increase the travel driving force, the control means is the transmission state switching means. Is switched to the transmission state for increasing the driving force. That is, the shift output of the continuously variable continuously variable transmission is transmitted to one of the pair of left and right traveling devices, and the shift output of the continuously variable transmission for turning is transmitted to the other of the pair of left and right traveling devices. It is switched to the state to transmit to. Then, the control means controls the operation of the actuator so that the turning continuously variable transmission has the same or substantially the same speed as the linearly variable continuously variable transmission.

  The shift output of the continuously variable transmission for straight travel is transmitted to one of the pair of left and right traveling devices, and the shift output of the continuously variable transmission for turning is also transmitted to the other of the pair of left and right traveling devices, Moreover, since the turning continuously variable transmission and the continuously variable continuously variable transmission have the same or substantially the same speed, a pair of left and right traveling devices are driven by each of the continuously variable transmissions. Therefore, in addition to the shift output of the continuously variable transmission for straight travel, the shift output of the continuously variable transmission for turning is used as the driving force.

  As a result, it is possible to drive a pair of left and right traveling devices with a large traveling driving force compared to those driven by only the speed change output of the continuously variable transmission for straight travel, for example, over the fence from inside the field. Thus, it is possible to perform straight traveling even when a large traveling driving force is temporarily required, such as when the vehicle escapes from the field.

  Also, the shift output of the continuously variable transmission for straight travel is transmitted to one of the pair of left and right traveling devices, and the shift output of the continuously variable transmission for turning is also transmitted to the other of the pair of left and right traveling devices. Because of this configuration, although there is a possibility that the straight running performance may be low, the shift output of the continuously variable continuously variable transmission and the shift output of the continuously variable transmission for turning are respectively transmitted to the pair of left and right traveling devices. Unlike the configuration, there is no unreasonable burden of absorbing the speed difference due to the friction between the members in the transmission mechanism, and therefore it is possible to execute the driving force increase type straight traveling control over a long period of time.

  Further, when the driving force increase command means is not instructed to increase the driving force, during straight traveling, the left and right traveling devices are driven at the same speed by the continuously variable transmission for straight traveling. In addition, at the time of turning, the pair of left and right traveling devices are separately driven by the continuously variable transmission for straight movement and the continuously variable transmission for turning, respectively. Thus, the vehicle can smoothly turn in a desired turning state due to the speed difference.

  Therefore, it is possible to appropriately perform straight traveling and to smoothly perform turning according to a desired turning state, but temporarily requires a large driving force during straight traveling. In such a case, it has become possible to provide a travel control device for a work vehicle that can solve the shortage of driving force and perform good straight traveling.

  According to a third feature configuration of the present invention, in addition to the first feature configuration or the second feature configuration, the transmission state switching means includes a shift output of the continuously variable continuously variable transmission and a continuously variable transmission of the turning. Each of the shift outputs is transmitted to one of the pair of left and right traveling devices located on the side opposite to the turning direction, and the other driving device is in a transmission cut-off state for increasing the driving force for turning. In the state where either the right turn or the left turn is commanded by the turn command means, the drive means increases the drive force by the drive force increase command means. Then, the transmission state switching means is switched to the driving force increasing type transmission state for turning, and the continuously variable transmission for turning has the same or substantially the same speed as the continuously variable continuously variable transmission. To control the operation of the actuator In that it is configured to perform turning control of the driving force increasing type that.

  According to the third feature configuration, in the state where either the right turn or the left turn is commanded by the turn command means, when the drive force increase command means is commanded to increase the drive force, The control means switches the transmission state switching means to the transmission state for increasing the driving force for turning. That is, the shift output of the continuously variable continuously variable transmission and the shift output of the continuously variable continuously variable transmission are each transmitted to one of the left and right traveling devices opposite to the turning direction. The other traveling device is switched to the transmission cut-off state. Then, the control means controls the operation of the actuator so that the turning continuously variable transmission has the same or substantially the same speed as the linearly variable continuously variable transmission.

  Since each of the shift output of the continuously variable transmission for straight travel and the shift output of the continuously variable transmission for turning is transmitted to one traveling device located on the opposite side to the turning direction, the traveling device is It is driven by each of the step transmissions. Therefore, in addition to the shift output of the continuously variable transmission for straight travel, the shift output of the continuously variable transmission for turning is used as the driving force.

  Therefore, compared with the case of driving with one continuously variable transmission, the one traveling device can be driven with a large traveling driving force. For example, the traveling device cannot be buried in mud and escape. Even when the vehicle cannot turn, the vehicle can turn with a large driving force.

  The fourth characteristic configuration of the present invention is that, in addition to the first characteristic configuration to the third characteristic configuration, the driving force increase command means is configured by an artificially operated switching operation tool.

  According to the fourth feature configuration, when the operator feels that the driving force is insufficient when the vehicle is traveling straight or turning, the manually operated switching tool is operated by the operator's intention. Can be commanded to increase the driving force. Therefore, when it is predicted by the operator's judgment that a large driving force is required, by instructing a driving force increase in advance, a disadvantage such as an engine stall due to a lack of driving force in the middle of traveling can occur beforehand. It is possible to avoid it.

[First Embodiment]
Hereinafter, the case where the 1st embodiment of the traveling control device of the working vehicle concerning the present invention is applied to the combine which is an example of a working vehicle is described based on a drawing.
FIG. 1 shows an entire side surface of a combine that is an example of a work vehicle. This combine is set at the front of a traveling machine body 2 that is driven by a pair of left and right crawler type traveling devices 1R and 1L. A threshing device 4 that removably couples the harvesting and transporting device 3 that harvests and transports the straw toward the rear, and receives the harvested cereal from the harvesting and transporting device 3 to the traveling machine body 2 and executes the threshing / sorting process; A grain tank 5 that stores grains from the threshing device 4 is mounted, and a boarding operation unit 6 is provided at a location in front of the grain tank 5.

Next, the transmission structure of this combine is demonstrated.
As shown in FIG. 2, the continuously variable transmission 7 for linear travel that can change the traveling speed in a straight traveling state and the traveling speed of the traveling device that is located on the turning center side during turning traveling can be varied for turning. Of the continuously variable transmission 8 and a transmission case 9 to which the power from the continuously variable transmissions 7 and 8 is input and the power to the left and right traveling devices 1R and 1L is output. ing. Each of the linearly variable continuously variable transmission 7 and the continuously variable continuously variable transmission 8 is driven by a transmission shaft 12 driven by a transmission belt 10 and a transmission pulley 11 from an engine mounted on a combine body. Hydrostatic continuously variable transmission (HST) having a well-known structure comprising a pair of variable hydraulic pumps 7A and 8A and hydraulic motors 7B and 8B that are rotationally driven by oil supplied from the variable hydraulic pumps 7A and 8A It is constituted by.

  In this combine, the transmission output of the continuously variable continuously variable transmission 7 is transmitted to each of the pair of left and right traveling devices 1R and 1L, and the transmission output of the continuously variable continuously variable transmission 7 is transmitted to the right. The left turn transmission state in which the shift output of the continuously variable transmission 8 for turning is transmitted to the left travel device 1L, and the shift output of the continuously variable continuously variable transmission 7 is transmitted to the left. Transmission state switching mechanism A as a transmission state switching means that can be switched to a right-turning transmission state that is transmitted to the right traveling device 1L and that transmits the shift output of the turning continuously variable transmission 8 to the right traveling device 1R. Is provided.

More specifically, the transmission case 9 has an output shaft 20 of the continuously variable transmission 7 for straight traveling and an output shaft 21 of the continuously variable transmission 8 for turning inserted therein. The power from both the output shafts 20 and 21 is transmitted to the pair of left and right traveling devices 1R and 1L, while the power of the continuously variable transmission 7 for straight travel is transmitted to the cutting and conveying device 3. Yes. A pair of large and small output gears 20a, 20b for sub-shifting and an output gear 20c for driving the cutting unit are fixed to the output shaft 20 of the continuously variable transmission 7 for linear movement.
The sub-transmission shaft 22 supports a sub-transmission small-diameter gear 22a and a large-diameter gear 22b that are always meshed with the output gears 20a and 20b, and is relatively rotatably supported. A sub-shift gear shift gear 22d that rotates integrally with the transmission shaft 22 is slidably fitted in the axial direction. A sub-transmission device is configured in which the shift gear 22d for sub-transmission is slid and operated to be shifted in two steps. An output gear 22e is fixed to the auxiliary transmission shaft 22, and a center gear 24 provided integrally with the support shaft 23 is provided in a state where the output gear 22e is always meshed with the output gear 22e.

  The support shaft 23 is switched on the left and right sides on either side of the center gear 24 so that the power transmitted through the center gear 24 can be input from either of the continuously variable transmissions 7, 8. A flexible transmission state switching mechanism A is provided. The transmission state switching mechanism A includes a pair of left and right multi-plate friction clutches 25 and 25 each having an outer peripheral gear portion 25 a linked to the transmission system of the continuously variable transmission 8 for turning on the outer peripheral portion, and the center gear 24. It is composed of a pair of left and right meshing clutches 27, 27 formed between both side surfaces and the shift gear 26 facing the both side surfaces.

  The left and right shift gears 26 can be shifted in the direction of the rotation axis in a state where they are engaged with the center gear 24 and in a state where they are not engaged with each other. When the right shift gear 26 is engaged with the center gear 24, the right engagement clutch 27 is configured to be switched so that the right engagement gear 27 is switched to the engagement state. Both shift gears 26 are engaged with the center gear 24, and the left and right traveling apparatuses 1 </ b> R, 1 </ b> L are driven straight through the shift gear 26 in the same direction at the same speed.

  More specifically, the left and right shift gears 26, 26 are urged into the engaged state in which the meshing clutches 27, 27 are engaged by the pressing force of the pressure springs 29, 29, respectively. The meshing clutches 27 and 27 are disengaged by supplying pressure oil to the hydraulic cylinders 31L and 31R, which are single acting hydraulic cylinders, against the pressing force of the pressing springs 29 and 29 and performing a shift operation. Switching operation is possible. As shown in FIG. 3, the hydraulic cylinders 31L and 31R for shutoff are configured to be operated by switching the solenoid valves 63 and 64 for cutoff between a pressure oil supply state and an oil discharge state.

  Further, by supplying pressure oil to the left steering hydraulic cylinder 30L of the left and right steering hydraulic cylinders 30L, 30R composed of a single-acting hydraulic cylinder, the friction plate in the shift gear 26 is shifted. The left friction clutch 25 is configured to be able to be switched to a transmission state where the friction clutch 25 is in pressure contact. On the other hand, by supplying pressure oil to the right steering hydraulic cylinder 30R and shifting the friction plate in the shift gear 26, the right friction is achieved. The clutch 25 is configured to be able to be switched to a transmission state in which the clutch 25 is pressed. As shown in FIG. 3, the pair of steering hydraulic cylinders 30L and 30R are configured to be operated by switching the shut-off solenoid valves 32 and 33 between the pressure oil supply state and the oil discharge state. .

  The power from the shift gear 26 is transmitted to the pair of left and right traveling devices 1R and 1L via the final gear 35. The shift gear 26 is always a traveling device whether the meshing clutch 27 is engaged or not. It is configured to mesh with the relay gear 34 of the transmission system.

  That is, when the left and right meshing clutches 27 and 27 are respectively engaged and the left and right friction clutches 25 and 25 are respectively disengaged, the straight transmission state is established, and the left meshing clutch 27 is disengaged from the straight transmission state. When the left friction clutch 25 is in the engaged state, a left-turn transmission state is established, and when the right engagement clutch 27 is disengaged and the right friction clutch 25 is engaged from the straight-ahead transmission state, the right-turn transmission state is established. Become.

  More specifically, transmission gears 21a and 21b are fixed to both ends of the output shaft 21 of the turning continuously variable transmission 8, and the friction clutches 25 and 25 are respectively attached to the transmission gears 21a and 21b. The outer peripheral gear portions 25a and 25a are meshed with each other. Then, by shifting one of the left and right shift gears 26, 26 by operating one of the cutoff hydraulic cylinders 31L, 31R, the shift operation is performed to the side where the meshing with the center gear 24 is disengaged. When the friction plate in the shift gear 26 is shifted by either one of the hydraulic cylinders 30L, 30R, the friction clutch 25 on the side to which the shift gear 26 has moved is brought into a pressure contact state, and the friction clutch 25 Then, the power of the continuously variable transmission 8 for turning is transmitted to the shift gear 26, and is transmitted from the shift gear 26 to one of the traveling devices via the relay gear 34 and the final gear 35, so that the aircraft turns. Further, the shift gear 26 meshes with the relay gear 34 of the transmission system to the traveling device both when meshed with the center gear 24 and when operated on the clutch engagement side of the friction clutch 25. It is configured as follows.

  The linearly variable continuously variable transmission device 7 is configured to be able to perform a stepless speed change operation from the neutral position in each of the forward rotation direction and the reverse rotation direction, and the boarding operation unit 6 has a predetermined direction along the front-rear direction. A main speed change lever 14 is provided as a speed change operation tool that can be swung by manual operation over the front and rear operation range. As shown in FIG. 3, the swash plate 13 of the variable hydraulic pump 7A is linked to the main transmission lever 14 via the hydraulic servo mechanism SV, and the angle of the swash plate 13 is changed based on an operation command of the main transmission lever 14. By doing so, the output state on the hydraulic motor 7B side is changed steplessly. That is, when the main speed change lever 14 is manually operated, the speed change operation can be lightly operated by performing an assist operation with a hydraulic operation force by the action of the hydraulic servo mechanism SV. It has become. Since the hydraulic servo mechanism SV has a well-known configuration, detailed description thereof is omitted here.

Next, the speed change operation configuration of the continuously variable transmission 7 for straight travel will be described.
As shown in FIG. 4, when the main transmission lever 14 is in the neutral range and the neutral state is commanded, the swash plate 13 is in the neutral state and the hydraulic motor 7B does not rotate and is maintained in the stopped state. Is a shift command to the forward speed increasing side or the reverse speed increasing side, the angle of the swash plate 13 is rotated in the forward rotation direction (by the hydraulic servo mechanism SV as described above in accordance with the operation command of the main shift lever 14 ( The hydraulic motor 7B is operated in the forward rotation direction or the reverse rotation direction at a speed corresponding to the command position by being operated by the assist force of the hydraulic operation force in the forward acceleration direction) or the reverse rotation direction (reverse acceleration direction). It is configured to perform a speed change operation.

  On the other hand, similarly to the continuously variable continuously variable transmission 7 for turning, the continuously variable transmission 8 for turning is configured to be capable of shifting operation in a stepless manner in each of the forward rotation direction and the reverse rotation direction. However, the continuously variable transmission 8 for turning is not manually shifted, but the swash plate 15 of the variable hydraulic pump 8A is linked to the hydraulic turning operation mechanism 16, and the turning operation mechanism 16 By changing the swash plate angle, the output state on the hydraulic motor 8B side is changed. As shown in FIG. 3, the turning operation mechanism 16 includes a double-acting shift hydraulic cylinder 17 (an example of an actuator) coupled to a swash plate 15 in a continuously variable transmission 8 for turning, And a hydraulic control unit VU that performs hydraulic control on the hydraulic cylinder 17 for operation. The transmission hydraulic cylinder 17 is configured to be urged to return to the neutral position by the urging force of a pair of left and right springs 17a and 17b provided therein.

  Although not described in detail, the hydraulic control unit VU moves the swash plate 15 in the continuously variable transmission 8 for turning in the forward speed increasing direction and the reverse speed increasing direction based on a control command from the control device H. The shift hydraulic cylinder 17 is controlled so as to move and hold the swash plate 15 at an arbitrary shift position.

  The shifting operation of the continuously variable transmissions 7 and 8 as described above will be described. If the shifting positions of the swash plates 13 and 15 are in a neutral region having a predetermined width including the neutral position N, as shown in FIG. The speed change output (output rotation speed) becomes zero, and when the speed change position of the swash plates 13 and 15 is rotated in a predetermined direction from the neutral range, the speed change output in the forward direction is steplessly increased. When the motors 13 and 15 are operated in the direction opposite to the predetermined direction from the neutral region, the shift output in the reverse direction is increased steplessly.

  The boarding operation unit 6 directly detects the swing operation amount of the main shift lever 14 as shift command position detection means for directly changing the shift command position commanded by the main shift lever 14. A potentiometer type shift lever detection sensor 65 for detection is provided. In addition to the main shift lever 14, a neutral operation area for a straight advance command having a predetermined width including the neutral position N, a left turn operation area for a left turn command operated in the forward direction from the neutral operation area, and A turn lever 56 is provided as a turn command means that can be moved and operated in the right turn operation range for a right turn command operated in the reverse direction from the neutral operation range. The command is such that the movement range is freely movable over the entire range of the predetermined operation area in each of the operation area for turning and the right turning operation area, and the smaller the movement amount in the direction away from the neutral operation area, the smaller the command. It is configured to command a target speed ratio for turning as information. In other words, a turning lever sensor 57 comprising a rotary potentiometer that detects the operation position of the turning lever 56 is provided, and in other words, the larger the amount of movement in the direction away from the neutral region in the turning command operation region, the more in other words, The command information is such that the greater the tilt angle from the neutral position N to the left or right, the greater the turning force.

  A linear shift position sensor 60 for detecting the operation position of the swash plate 13 as an object to be shifted in the linearly variable continuously variable transmission 7 operated by the servo mechanism SV is provided. A potentiometer-type turning position detecting sensor 61 for turning is provided as a turning position detecting means for turning which detects an operation position of a swash plate 15 as an object to be changed in the continuously variable transmission 8. On the other hand, a rotation sensor 58 that detects the output rotation speed of the continuously variable transmission 7 for straight travel by counting the number of teeth of the output gear 22e, and the output rotation speed of the continuously variable transmission 8 for turning are described above. A rotation sensor 59 is provided for detection by counting the number of teeth of the transmission gear 21a.

  And based on the input information of various sensors as described above, the operation of the shifting hydraulic cylinder 17 is controlled to control the speed of the continuously variable transmission 8 for turning, and the steering hydraulic cylinder 30R, A control device H using a microcomputer is provided as a control means for switching the transmission state of the transmission state switching mechanism A by controlling the operation of the hydraulic cylinders 30L, 31L, and 31R.

  When the control device H is commanded to go straight by operating the turning lever 56, the control device H switches the transmission state switching mechanism A to the transmission state for straight running, and the continuously variable transmission 8 for turning makes the speed change state for straight travel. When the right turn is commanded by the turning lever 56, the transmission state switching mechanism A is switched to the right turning transmission state. When the turning lever 56 is commanded to turn left, the transmission state switching mechanism A is switched to the left turning transmission state, and the hydraulic cylinder 17 is operated so that the continuously variable transmission 8 for turning is in the shifting state for turning. It is comprised so that the shift transmission control for turning may be performed.

  Then, the control device H performs the turning shift control based on the output rotational speed of the continuously variable transmission 8 for turning based on the command information of the turning lever 56 and the output rotational speed of the continuously variable continuously variable transmission 7. The rotational speed control for controlling the operation of the hydraulic cylinder 17 for shifting so as to reach the set target output rotational speed, and the operation position of the swash plate 15 in the continuously variable transmission 8 for turning are command information of the turning lever 56. In addition, the shift position control for controlling the operation of the shift hydraulic cylinder 17 so as to become the target shift position set based on the information of the operation position of the swash plate 13 in the continuously variable transmission 7 for straight travel is executed. It is configured.

  In this combine, for example, when a large driving force is temporarily required, such as over a ridge, an increase in the driving force is used as a driving force increase command means. And is configured to be able to temporarily output a large driving force.

  In other words, the transmission state switching mechanism A transmits the shift output of the continuously variable continuously variable transmission 7 to each of the pair of left and right traveling apparatuses 1R and 1L, and the turning of the continuously variable transmission 8 for turning. The transmission output is transmitted to the pair of left and right traveling devices 1R and 1L, and can be switched to a straight drive driving force increasing transmission state. Further, a transmission state switching mechanism A is provided for the continuously variable transmission 7 for straight traveling. Each of the shift output and the shift output of the continuously variable transmission 8 for turning is transmitted to one of the left and right traveling devices 1R and 1L that is located on the opposite side of the turning direction, and the other traveling device is transmitted to the other. It is configured to be switchable to a driving force increasing type transmission state for turning to a transmission cut-off state.

  Then, in a state where the rectilinear advance is commanded by the turning lever 56, the control device H causes the transmission state switching mechanism A to increase the driving force for rectilinear advance when the switching command tool 70 instructs to increase the travel driving force. A driving force increasing type that controls the operation of the shift hydraulic cylinder 17 so that the continuously variable transmission 8 for turning is set to the same or substantially the same speed as the continuously variable continuously variable transmission 7. The vehicle is configured to execute straight traveling control.

  Further, in the state where either the right turn or the left turn is instructed by the turning lever 56, if the increase of the driving force is instructed by the switching command tool 70, the transmission state switching mechanism A is used for turning. Drive for controlling the operation of the hydraulic cylinder 17 for shifting so that the continuously variable transmission 8 for turning is at the same or substantially the same speed as the continuously variable transmission 7 for straight travel. It is configured to execute force-increasing turning traveling control.

  The switching command tool 70 is provided on the operation panel of the boarding operation unit 6 and is provided at a location hidden by a hidden plate so as not to be mistakenly operated by a normal driving operation. It is configured to operate only when power is required.

Next, control by the control device H will be described based on the flowcharts of FIGS. 6 and 7.
When the turning lever 56 is operated in the neutral operation range, straight control as described later is executed (steps 1 and 2), and the turning lever 56 moves away from the neutral operation range and is used for turning operation or right turning. It is determined whether or not an increase in driving force is instructed by the switching command tool 70 when the operation area is being operated (step 3).

  At that time, if the turning lever 56 is operated to the right turning operation range in a state where no increase in driving force is commanded, the left steering hydraulic cylinder 30L and the left cutoff hydraulic cylinder 31L are drained. In this state, pressure oil is supplied to the right steering hydraulic cylinder 30R and the right shut-off hydraulic cylinder 31R and operated to switch the transmission state switching mechanism A to the right-turning transmission state (steps 4, 5). ). That is, the left mesh clutch 27 is switched to the engaged state, and the right mesh clutch 27 is switched to the disconnected state. Further, the left friction clutch 25 is switched to the disconnected state, and the right friction clutch 25 is switched to the engaged state.

On the other hand, when the turning lever 56 is operated to the left turning operation range, the right steering hydraulic cylinder 30R and the right shut-off hydraulic cylinder 31R are drained, and the left steering hydraulic cylinder 30L and the left Is operated by supplying pressure oil to the shutoff hydraulic cylinder 31L to switch the transmission state switching mechanism A to the left-turning transmission state (step 6). That is, the left meshing clutch 27 is switched to the disengaged state, and the right meshing clutch 27 is switched to the engaged state. Further, the left friction clutch 25 is switched to the engaged state, and the right friction clutch 25 is switched to the disconnected state.
In other words, the state is switched to a transmission state in which the traveling device on the turning side is driven by the continuously variable transmission 8 for turning, and the traveling device on the side opposite to the turning side is driven by the continuously variable transmission 7 for traveling straight.

  Next, it is determined whether or not acceleration / deceleration has been commanded by operating the main shift lever 14 based on whether or not the detection value of the shift position detection sensor 60 for straight travel changes by a set amount or more per set unit time. If it is determined that acceleration / deceleration has been commanded by operating the lever 14, the following shift position control is executed (step 7).

  The left and right traveling devices 1R and 1L have the same rotational direction, and the turning lever 56 commands the speed ratio between the shifting output of the continuously variable transmission 8 for turning and the shifting output of the continuously variable transmission 7 for straight traveling. The target shift position of the swash plate 15 in the continuously variable transmission 8 for turning is obtained by calculation so that the speed ratio corresponds to the turning radius of the turning (step 8).

  The processing for obtaining the target shift position will be further described. The amount of movement of the turning lever 56 in the direction away from the neutral operation area in the right turning operation area or the left turning operation area and the speed ratio corresponding to the turning radius. The relationship is determined and stored as a relationship corresponding to a quadratic function as shown in FIG. On the other hand, the target shift position of the continuously variable transmission 8 for turning is determined from the shift position of the continuously variable transmission 7 for straight movement detected by the shift position sensor 60 for linear movement and the function having the relationship shown in FIG. Is demanded.

  Then, the shift operation is performed by controlling the operation of the shift hydraulic cylinder 17 so that the shift position of the continuously variable transmission 8 for turning detected by the shift position detecting sensor 61 for turning becomes the target shift position (step). 9, 10, 11). Incidentally, the speed change position of the continuously variable transmission 7 for straight traveling is adjusted by manual operation with respect to the speed change lever 14.

  If the relationship shown in FIG. 5 is described further, a line L1 in FIG. Line L2 shows the change in the target rotation speed in the slow turning mode, line L3 shows the change in the target rotation speed in the trust turning mode, and line L4 shows the change in the target rotation speed in the super turning turn mode, The turning mode designated by the turning mode switching tool 62 for switching the turning mode to three stages by the dial operation is selected. In the gentle turning mode indicated by the line L2, when the turning lever 56 is operated to the maximum operating position, the turning-side traveling device is decelerated to a speed that is about 1/3 of the traveling speed V of the opposite-side traveling device. As described above, the change characteristic of the speed ratio of the left and right traveling apparatuses 1R and 1L with respect to the operation position of the turning lever 56 is set in advance. In the belief turning mode indicated by the line L3, when the turning lever 56 is operated to the maximum operating position, the operation position of the turning lever 56 is decelerated until the traveling speed of the turning side traveling device becomes zero. The speed ratio of the left and right traveling devices 1R, 1L is preset. Also, in the super turning mode indicated by the line L4, when the turning lever 56 is operated to the maximum operating position, the running speed of the turning side traveling device rotates in the opposite direction to the drive rotation direction of the opposite side traveling device. The speed ratio of the left and right traveling apparatuses 1R and 1L with respect to the operation position of the turning lever 56 is set in advance so that the speed is the same as the speed of the opposite traveling apparatus.

  When the turning is instructed by the turning lever 56 and acceleration / deceleration is not instructed by the operation of the main transmission lever 14, in other words, when the same speed is instructed by the main transmission lever 14, left and right The traveling devices 1R and 1L have the same rotational direction, and the turning lever 56 commands a speed ratio between the output rotational speed of the continuously variable transmission 8 for turning and the output rotational speed of the continuously variable transmission 7 for straight traveling. The target rotational speed for the continuously variable transmission 8 for turning is obtained by calculation so that the target speed ratio corresponding to the turning radius is obtained (step 12).

  The processing for obtaining the target rotational speed by calculation will be further described. The output rotational speed of the continuously variable transmission 7 for straight travel detected by the rotational sensor 58 and the quadratic function as shown in FIG. The target rotational speed of the continuously variable transmission 8 for turning is obtained from a function determined as a relationship corresponding to the above. Next, rotational speed control for controlling the shift hydraulic cylinder 17 is executed so that the output rotational speed detected by the rotational sensor 59 becomes the target rotational speed (step 13).

  Briefly describing this rotational speed control, a deviation between the output rotational speed detected by the rotational sensor 59 and the target rotational speed is obtained, and a target operation amount for operating the swash plate 15 is calculated based on the deviation. To do. Further, the target shift position of the swash plate 15 is obtained from the target operation amount and the current shift position of the swash plate 15 detected by the shift position sensor 61, and the shift position of the swash plate 15 becomes the target shift position. Thus, the shifting hydraulic cylinder 17 is shifted, and when the shifting position of the swash plate 15 reaches the target shifting position, the operation of the shifting hydraulic cylinder 17 is stopped. By repeatedly executing such processing every unit time, the output rotation speed is controlled to be the target rotation speed.

  When it is determined in step 3 that an increase in driving force has been commanded, if the turning lever 56 is operated to the right turning operation area, the left steering hydraulic cylinder 30L and the right cutoff hydraulic pressure are used. Pressure oil is supplied to the cylinder 31R to operate, and the right steering hydraulic cylinder 30R and the left shut-off hydraulic cylinder 31L are respectively drained, and the transmission state switching mechanism A is turned for the right turning operation. Switch to the increased drive force transmission state. That is, the left mesh clutch 27 is switched to the engaged state, and the right mesh clutch 27 is switched to the disconnected state. Further, the left friction clutch 25 is switched to the engaged state, and the right friction clutch 25 is switched to the disconnected state (steps 14 and 15).

  On the other hand, when the turning lever 56 is operated to the left turning operation area, the left steering hydraulic cylinder 30L and the right shut-off hydraulic cylinder 31R are respectively drained, and the right steering hydraulic cylinder 30R. In addition, pressure oil is supplied to the left cutoff hydraulic cylinder 31L to operate, and the transmission state switching mechanism A is switched to a driving force increase type transmission state for turning for a left turning operation. That is, the left meshing clutch 27 is switched to the disengaged state, and the right meshing clutch 27 is switched to the engaged state. Further, the left friction clutch is switched to the disengaged state, and the right friction clutch is switched to the engaged state (step 16).

  That is, one of the shift output of the continuously variable continuously variable transmission device 7 and the shift output of the continuously variable transmission device 8 for turning is located on the opposite side to the turning direction of the pair of left and right traveling devices 1R and 1L. This is transmitted to the traveling device, and the other traveling device is brought into the transmission cut-off state.

  Then, the same value as the output rotational speed of the continuously variable transmission 7 for straight travel detected by the rotation sensor 58 is set as the target rotational speed of the continuously variable transmission 8 for turning (step 17). Similarly, rotational speed control is executed to control the operation of the hydraulic cylinder 17 for shifting so that the output rotational speed of the continuously variable transmission 8 for turning detected by the rotation sensor 59 becomes the target rotational speed ( Step 18).

  By controlling in this way, each of the shift output of the continuously variable transmission 7 for straight traveling and the shift output of the continuously variable transmission 8 for turning is transmitted to one traveling device located on the opposite side to the turning direction. Therefore, the traveling device is driven by each of the continuously variable transmissions 7 and 8.

  When the turning lever 56 is in the neutral position, the straight-ahead control is executed. In this straight-ahead control, as shown in FIG. 7, it is determined whether or not an increase in driving force is commanded by the switching command tool 70 (step 19). At that time, if the increase in driving force is not commanded, the pair of steering hydraulic cylinders 30L, 30R and the cutoff hydraulic cylinders 31L, 31R are respectively in an oil drained state, and the transmission state switching mechanism A is transmitted in a straight line. Switch to state. That is, the left and right meshing clutches 27, 27 are both switched to the engaged state, and the left and right friction clutches 25, 25 are both switched to the disconnected state (step 20).

  Then, it is determined whether or not an acceleration / deceleration is instructed to the continuously variable transmission 7 for linear travel based on the detection value of the linear shift position sensor 60 (step 21). When the command is issued, the shift position of the swash plate 13 in the continuously variable transmission 7 for straight travel is set as the target shift position corresponding to the shift state for straight travel (step 22). Next, the operation of the shift hydraulic cylinder 17 is controlled so that the shift position of the swash plate 15 in the continuously variable transmission 8 for turning becomes the target shift position set as described above (steps 23 and 24). 25).

  If it is determined in step 21 that acceleration / deceleration is not instructed for the continuously variable transmission 7 for straight travel, the same value as the output rotational speed of the continuously variable transmission 7 for straight travel detected by the rotation sensor 58 is detected. Is set as the target rotational speed of the continuously variable transmission 8 for turning (step 26). Then, the rotational speed control similar to step 13 for controlling the operation of the hydraulic cylinder for shifting 17 so that the output rotational speed of the continuously variable transmission 8 for turning detected by the rotation sensor 59 becomes the target output rotational speed. Is executed (step 27).

  If it is determined in step 19 that an increase in driving force is instructed, the left and right shut-off hydraulic cylinders 31R and 31L are drained and pressure oil is supplied to the left and right steering hydraulic cylinders 30R and 30L. Thus, the transmission state switching mechanism A is switched to the drive force increase type transmission state for straight travel. That is, the left and right meshing clutches 27 are switched to the joint state, and the left and right friction clutches 25 are switched to the joint state (step 28). Then, the same value as the output rotational speed of the continuously variable transmission 7 for straight traveling detected by the rotation sensor 58 is set as the target rotational speed of the continuously variable transmission 8 for turning and detected by the rotation sensor 59. Rotational speed control for controlling the operation of the shift hydraulic cylinder 17 is executed so that the output rotational speed of the continuously variable transmission 8 for turning is equal to the target rotational speed (steps 26 and 27).

  By controlling in this way, the shift output of each of the continuously variable transmission 7 for straight travel and the continuously variable transmission 8 for turning is transmitted to each of the pair of left and right traveling devices 1R, 1L. In addition to the speed change output of the continuously variable transmission 7 for straight travel, the speed change output of the continuously variable transmission 8 for turning is also transmitted to the travel devices 1R and 1L of the vehicle. Can be obtained, and the crossing of ridges can be satisfactorily performed.

  When executing the straight-ahead control, the turning continuously variable transmission 8 does not transmit power to any of the traveling devices, so there is no function for shifting the traveling speed of the traveling device by automatic control. The turning operation is performed by the turning lever 56 by rotating in the same direction as the rotation direction of the continuously variable continuously variable transmission 7 that is changed by the operation so as to reach the target shift position or the target output rotation speed as described above. When commanded and switched to the turning transmission state, a shock caused by the speed difference between the continuously variable transmission 7 for straight travel and the continuously variable transmission 8 for turning is prevented. In addition, when the speed increasing / decreasing operation is being performed, the vehicle moves at a constant speed or almost a constant speed while reducing the speed difference between the left and right traveling devices due to the follow-up delay caused by the rotational speed control by executing the shift position control. In this case, the rotational speed control is executed to reduce the speed difference between the left and right traveling apparatuses 1R and 1L due to the difference in traveling load.

[Second Embodiment]
Hereinafter, 2nd Embodiment of the traveling control apparatus of the working vehicle which concerns on this invention is described.
In the second embodiment, the configuration is the same as that of the first embodiment except that the control method when the drive force increase in the straight-ahead control is instructed is the same as that of the first embodiment. The description of the configuration is omitted.

  That is, in this embodiment, the transmission state switching mechanism A transmits the shift output of the continuously variable continuously variable transmission 7 to either one of the pair of left and right traveling apparatuses 1R, 1L, and for turning. The continuously variable transmission 8 can be switched to a straight driving force increasing transmission state for transmitting the shift output to the other of the pair of left and right traveling devices 1R, 1L. In the state where the straight movement is commanded by the turning lever 56 as the turning command means, when the increase of the driving force is instructed by the switching command tool 70 as the driving force increase command means, the transmission state switching mechanism A is The shift hydraulic cylinder 17 serving as an actuator is switched to a straight drive power increase type transmission state, and the turning continuously variable transmission 8 has the same or substantially the same speed as the continuously variable continuously variable transmission 7. It is configured to perform a straight traveling control of the driving force increasing type for controlling the movement.

  Specifically, using the flowchart shown in FIG. 8, whether or not the turning lever 56 is in the neutral position and whether or not the switching command tool 70 is instructed to increase the driving force when the straight-ahead control is executed. (Step 30), and at that time, when the driving force increase is not instructed, the same control as in the first embodiment is executed (steps 31 to 38). Then, if an increase in driving force is instructed by the switching command tool 70, the left steering hydraulic cylinder 30L and the left shut-off hydraulic cylinder 31L are put into an oil drained state, respectively, and the right steering hydraulic cylinder 30R. Then, pressure oil is supplied to the hydraulic cylinder 31R on the right side and operated to switch the transmission state switching mechanism A to the straight drive driving force increasing type transmission state. That is, the left meshing clutch 27 is switched to the clutch engaged state, and the right meshing clutch 27 is switched to the clutch disengaged state. Further, the left friction clutch 25 is switched to the clutch disengaged state, and the right friction clutch 25 is switched to the clutch engaged state (step 39). Then, the same value as the output rotational speed of the continuously variable transmission 7 for straight traveling detected by the rotation sensor 58 is set as the target rotational speed of the continuously variable transmission 8 for turning and detected by the rotation sensor 59. Rotational speed control is executed to control the operation of the hydraulic cylinder 17 for shifting so that the output rotational speed of the continuously variable transmission 8 for turning is equal to the target rotational speed (steps 37 and 38).

  By controlling in this way, the shift output of the continuously variable transmission 7 for straight travel is transmitted to the left traveling device 1L, and the shift output of the continuously variable transmission 8 for turning is transmitted to the right traveling device 1R. Since the turning continuously variable transmission 8 is controlled so as to have the same or substantially the same speed as the continuously variable continuously variable transmission 7, when the vehicle travels straight, the shift output of the continuously variable continuously variable transmission 7 and A large driving force can be obtained by the shift output of the continuously variable transmission 8 for turning, and the overpass can be satisfactorily performed.

[Another embodiment]
Hereinafter, other embodiments are listed.

(1) In each of the above-described embodiments, when an increase in driving force is commanded by the driving force increase command unit in a state where either of the right turn and the left turn is commanded by the turn command unit, Although the control means is exemplified to execute the driving force increase type turning traveling control, it may be configured not to execute such driving force increase type turning traveling control.

(2) In the second embodiment, when the driving force increase type straight traveling control is executed, the shift output of the continuously variable transmission 7 for straight traveling is transmitted to the left traveling device 1L, and no turning The shift output of the step transmission 8 is switched to the configuration in which it is transmitted to the left travel device 1R. Instead of such a configuration, the shift output of the continuously variable transmission 7 for straight travel is the right travel device 1R. The shift output of the continuously variable transmission 8 for turning may be switched to a configuration in which the shift output is transmitted to the left traveling device 1L.

(3) In each of the above embodiments, the driving force increase command means is configured by a manually operated switching operation tool and is exemplified by switching by manual operation. However, instead of the manual operation type, a stepping operation type is used. It may be configured. Moreover, it may replace with what is comprised with such an artificial operation type switching operation tool, and may comprise as follows.

  For example, while the transmission state switching mechanism A is switched to the linear transmission state and the vehicle travels straight, the control device automatically determines a state where the driving force is insufficient, and the control device When such a state is discriminated, the driving force increasing type straight traveling control may be automatically executed. As a configuration for automatically determining the state in which the driving force is insufficient, for example, when the vehicle is traveling straight in a non-working state, for example, the engine rotational speed is reduced to a predetermined lower limit or lower. In some cases, it may be determined that the engine load is an excessive value that is equal to or greater than the preset allowable upper limit value. In addition, it is possible to determine the lack of driving force in various forms. It is.

(4) In the above-described embodiment, the turning command means includes a turning lever that can be swung right and left, and a potentiometer-type turning lever sensor that detects the operation position. For example, a configuration including a plurality of switches for detecting the operation position of the turning lever, a configuration for instructing to change the turning radius according to the time for pressing the left and right switches instead of the turning lever, etc. The present invention may be implemented in various forms.

(5) In each of the above embodiments, the hydraulic cylinder is exemplified as the actuator for shifting the turning continuously variable transmission. However, other actuators such as a hydraulic motor and an electric motor may be used.

(6) In each of the above-described embodiments, a non-hydraulic continuously variable transmission is used as each of the linearly variable continuously variable transmission and the turning continuously variable transmission. However, a belt-type continuously variable transmission, Various types of continuously variable transmissions such as a tapered cone type continuously variable transmission can be used.

(7) In the above embodiments, the combine is exemplified as the work vehicle. However, the combine is not limited to the combine, and a tractor or other agricultural machine may be used, or a construction work vehicle or the like may be used.

Combine side view Schematic configuration diagram showing transmission structure Control block diagram The figure which shows the relationship between the shift position and the shift output The figure which shows the relationship between the operation position of the turning lever and the speed ratio Flow chart of control operation Flow chart of control operation Flow chart of control operation

Explanation of symbols

1R, 1L traveling device 7 continuously variable transmission 8 for straight traveling 8 continuously variable transmission 14 for turning 14 transmission operation tool 17 actuator 56 turning command means 70 driving force increase command means A transmission state switching means H control means

Claims (4)

The transmission output of the straight-line continuously variable transmission is transmitted to each of the pair of left and right traveling devices, the transmission output of the continuously variable continuously variable transmission is transmitted to the right-side traveling device, and A transmission state for turning left that transmits the shift output of the step transmission to the left traveling device, and a continuously variable transmission for transmitting the transmission output of the continuously variable continuously variable transmission to the left traveling device Transmission state switching means that can be switched to a right-turning transmission state that transmits a shift output of
An actuator for shifting the turning continuously variable transmission,
A manually operated shift operation tool for shifting the continuously variable continuously variable transmission by manual operation;
Turn command means for commanding straight, right turn, and left turn;
Control means for controlling the operation of the transmission state switching means and the actuator,
The control means is
When the rectilinear command is instructed by the turning command means, the transmission state switching means is controlled to switch to the straight transmission state,
When a right turn is commanded by the turn command means, the transmission state switching means is switched to the right turn transmission state so that the continuously variable transmission for turning has a target speed for turning. When the operation of the actuator is controlled and a left turn is commanded by the turn command means, the transmission state switching means is switched to the left turn transmission state, and the continuously variable transmission for turning is used for turning. A travel control device for a work vehicle configured to control the operation of the actuator to achieve a target speed,
A driving force increase command means for commanding an increase in traveling driving force is provided,
The transmission state switching means transmits a shift output of the continuously variable continuously variable transmission device to each of the pair of left and right traveling devices, and transmits a shift output of the continuously variable transmission device for turning to the pair of left and right traveling devices. It is configured to be able to switch to a driving force increase type transmission state for straight traveling that is transmitted to each,
When the control means is instructed to increase the travel driving force by the driving force increase command means in a state where the straight movement is instructed by the turning command means, the transmission state switching means is moved to the straight drive. Driving force increasing type linear advance that switches to a force increasing type transmission state and controls the operation of the actuator so that the turning continuously variable transmission has the same or substantially the same speed as the linearly variable continuously variable transmission A travel control device for a work vehicle configured to execute travel control. The transmission output of the straight-line continuously variable transmission is transmitted to each of the pair of left and right traveling devices, the transmission output of the continuously variable continuously variable transmission is transmitted to the right-side traveling device, and A transmission state for turning left that transmits the shift output of the step transmission to the left traveling device, and a continuously variable transmission for transmitting the transmission output of the continuously variable continuously variable transmission to the left traveling device Transmission state switching means that can be switched to a right-turning transmission state that transmits a shift output of
An actuator for shifting the turning continuously variable transmission,
A manually operated shift operation tool for shifting the continuously variable continuously variable transmission by manual operation;
Turn command means for commanding straight, right turn, and left turn;
Control means for controlling the operation of the transmission state switching means and the actuator,
The control means is
When the rectilinear command is instructed by the turning command means, the transmission state switching means is controlled to switch to the straight transmission state,
When a right turn is commanded by the turn command means, the transmission state switching means is switched to the right turn transmission state so that the continuously variable transmission for turning has a target speed for turning. When the operation of the actuator is controlled and a left turn is commanded by the turn command means, the transmission state switching means is switched to the left turn transmission state, and the continuously variable transmission for turning is used for turning. A travel control device for a work vehicle configured to control the operation of the actuator to achieve a target speed,
A driving force increase command means for commanding an increase in traveling driving force is provided,
The transmission state switching means transmits the shift output of the continuously variable continuously variable transmission to either one of the pair of left and right traveling devices, and transmits the shift output of the continuously variable transmission for turning to the left and right pair. It is configured to be switchable to a driving force increase type transmission state for straight traveling transmitted to the other of the traveling devices of
When the control means is commanded to increase the driving force by the driving force increase command means in the state where the straight command is commanded by the turning command means, the transmission state switching means is changed to the driving force for straight travel. Driving force increasing type linear travel that switches to the increased transmission state and controls the operation of the actuator so that the turning continuously variable transmission has the same or substantially the same speed as the linearly variable continuously variable transmission A travel control device for a work vehicle configured to execute control. The transmission state switching means positions the shift output of the continuously variable transmission for straight travel and the shift output of the continuously variable transmission for turning on the opposite side to the turning direction of the pair of left and right traveling devices. Is transmitted to one traveling device, and is configured to be freely switchable to a turning driving force increasing transmission state for turning the other traveling device into a transmission cut-off state,
When the control means is instructed to increase the driving force by the driving force increase command means in a state where either the right turn or the left turn is instructed by the turning command means, the transmission state The switching means is switched to the driving force increasing transmission state for turning, and the actuator is operated so that the turning continuously variable transmission has the same or substantially the same speed as the continuously variable continuously variable transmission. The traveling control device for a work vehicle according to claim 1, wherein the traveling control device is configured to execute a turning traveling control with an increased driving force to be controlled.   The travel control device for a work vehicle according to any one of claims 1 to 3, wherein the driving force increase command means is configured by a manually operated switching operation tool.

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