JP5805022B2 - Work vehicle turning operation structure - Google Patents

Description

  The present invention relates to a pair of left and right traveling devices, two hydraulically operated braking devices that brake the corresponding traveling devices, a valve unit that changes operating pressures on the two braking devices, and an operation of a steering operation tool. An operation angle detector for detecting an angle; and a turning control unit for controlling the operation of the valve unit. The turning control unit brakes a traveling device inside the turning based on the detection of the operation angle detector. The travel unit inside the turn is braked by controlling the operation of the valve unit so that the opening degree of the valve unit related to the operating pressure of the braking device is the opening degree corresponding to the operating angle of the steering operating tool. A turning operation structure for a work vehicle configured to adjust the braking force applied to the traveling device inside the turn by changing the operation pressure to the braking device to an operation pressure corresponding to the operation angle of the steering operating tool. On.

  As a turning operation structure of a work vehicle as described above, the steering operation tool (steering lever) is braked on the inner side of the turning as the operation angle from the straight traveling position (neutral position) is increased in either the left or right braking operation region. The opening degree of the valve unit related to the operating pressure of the braking device (hereinafter referred to as the braking device on the inside of the turn) that brakes the traveling device on the inside of the turn corresponding to the operation direction of the steering operating tool in a state where the operation pressure on the device becomes large The steering operation tool is linked to the valve unit via the operation angle detector and the turning control unit (linkage mechanism) so that the braking force applied to the traveling device on the inside of the turning is reduced. There is a configuration in which the vehicle body can be quickly adjusted according to the operation angle and the vehicle body can be smoothly turned with a turning radius corresponding to the adjusted braking force (see, for example, Patent Document 1).

JP 2008-261400 A (paragraph numbers 0030, 0035, 0036, FIG. 2)

  By the way, in the turning operation structure of the work vehicle as described above, when the steering operating tool is operated to the limit operating angle, the opening degree of the valve unit related to the operating pressure of the braking device inside the turning becomes the limit operating angle of the steering operating tool. As a result, the operating pressure applied to the braking device inside the turning reaches a large operating pressure corresponding to the limit operating angle of the steering operation tool. The brake is locked by a braking force applied by the braking device on the inner side of the turn.

  In addition, for example, due to a change in the oil temperature, the operating pressure applied to the braking device on the inner side of the turning is limited to the limit operating angle of the steering operating tool even though the steering operating tool is operated to the limit operating angle. Therefore, the operating pressure on the braking device inside the turning is not suitable for steering because the traveling device on the inside of the turning does not reach the braking lock state or due to individual differences of the braking device. In order to avoid the possibility of inconveniences such as the traveling device inside the turning not reaching the braking lock state despite the fact that the operating pressure has increased to a large operating pressure corresponding to the limit operating angle of the operating tool, When the control unit detects that the steering operating tool reaches the limit operating angle based on the detection of the operating angle detector, the opening degree of the valve unit related to the operating pressure of the braking device inside the turning is the limit of the steering operating tool. operation To switch from the corresponding opening at a stroke to an opening for maximum pressure setting in, and configured to control the operation of the valve unit.

  However, when the operation of the valve unit is controlled as described above, the operating pressure on the braking device on the inner side of the turning suddenly increases toward the maximum pressure as the steering operating tool reaches the limit operating angle. For this reason, when the traveling device inside the turn has not reached the braking lock state regardless of the operation of the steering operation tool to the limit operation angle, the vehicle travels inside the turn after the steering operation tool reaches the limit operation angle. While the time lag until the device reaches the brake lock state can be shortened, the operation pressure for the brake device inside the turn when the steering operation tool reaches the limit operation angle and the turn to obtain the brake lock state The greater the difference from the operating pressure applied to the inner braking device, the more suddenly the braking force applied by the inner braking device to the inner traveling device will increase with the operating pressure applied to the inner braking device. A shock due to a sudden increase in braking force is likely to occur during braking turning.

  The object of the present invention is to operate the steering operating tool to the limit operating angle without causing the inconvenience of shock due to a sudden increase in the braking force applied to the traveling device inside the turning during braking turning. In spite of this, it is possible to avoid the possibility that the traveling device inside the turn will not be brought into the braking lock state.

The invention according to claim 1 of the present invention includes a pair of left and right traveling devices, two hydraulically operated braking devices that brake the corresponding traveling devices, and a valve unit that changes operating pressures on the two braking devices. An operation angle detector that detects an operation angle of the steering operation tool, and a turning control unit that controls the operation of the valve unit, the turning control unit based on the detection of the operation angle detector, By controlling the operation of the valve unit so that the opening of the valve unit related to the operating pressure of the braking device that brakes the traveling device inside the turning becomes an opening corresponding to the operating angle of the steering operating tool, The operation pressure applied to the braking device for braking the inner traveling device is changed to an operation pressure corresponding to the operation angle of the steering operating tool, and the braking force applied to the inner traveling device is adjusted. In turning operation structure of the work vehicle,
When the turning control unit detects that the steering operating tool has reached the limit operating angle based on the detection of the operating angle detector, the valve unit related to the operating pressure of the braking device that brakes the traveling device inside the turning is detected. The operation of the valve unit is controlled such that the opening gradually changes at a preset change rate from the opening corresponding to the limit operating angle to the opening for maximum pressure setting.

  In the above invention, when the steering operating tool is operated to the limit operating angle during the braking turn, the opening of the valve unit related to the operation pressure of the braking device that brakes the traveling device inside the turning is accompanied by the steering operation. It gradually changes at a preset change rate from the opening corresponding to the limit operating angle of the tool to the opening for setting the maximum pressure.

  As a result, at the stage where the steering operating tool is operated to the limit operating angle, for example, due to a change in the oil temperature or the like, the steering operating tool is operated to the limit operating angle. Due to the fact that the operating pressure on the braking device does not increase to a large operating pressure corresponding to the limit operating angle of the steering operating tool, the traveling device inside the turn does not reach the braking lock state, or due to individual differences in the braking device, etc. Then, although the operating pressure on the braking device inside the turning has increased to a large operating pressure corresponding to the limit operating angle of the steering operation tool, the traveling device inside the turning does not reach the braking lock state. Even if inconveniences such as occur, the control pressure of the turning control unit after operating the steering operating tool to the limit operating angle, the operating pressure on the braking device inside the turning, regardless of the change in oil temperature, etc. To a maximum operating pressure higher than the maximum operating pressure corresponding to the limit operating angle of the rudder operating tool or the large operating pressure required to obtain the braking lock state of the traveling device regardless of individual differences in the braking device Thus, the change rate of the operating pressure can be gradually increased while being limited to the set change rate.

  As a result, it is possible to gradually and reliably increase the braking force applied to the traveling device inside the turning by the braking device inside the turning to the large braking force necessary to obtain the braking lock state of the traveling device at the time of braking turning. it can.

  Therefore, during braking turning, the steering operating tool is operated to the limit operating angle without incurring the inconvenience of generating shock due to a sudden increase in the braking force applied to the traveling device inside the turning. Nevertheless, it is possible to avoid the possibility of the inconvenience that the traveling device inside the turn does not reach the braking lock state, and thereby the vehicle traveling state is controlled by the operation to the limit operation angle of the steering operation tool. Thus, it is possible to reliably and smoothly switch to the small turning state in which the traveling device inside the turning is in the braking locked state.

The invention according to claim 2 of the present invention is the invention according to claim 1,
Until the turning control unit detects that the steering operating tool has reached the limit operating angle based on the detection of the operating angle detector, the steering based on the detection of the operating angle detector. The operating speed of the operating tool is determined, and when the determined operating speed exceeds a preset speed limit, the rate of change of the opening degree of the valve unit related to the operating pressure of the braking device that brakes the traveling device inside the turn is determined in advance. When it is detected that the set limit change rate is exceeded, the change rate of the opening degree of the valve unit is limited to the limit change rate.

  In the above invention, the opening degree of the valve unit related to the operating pressure of the braking device that brakes the traveling device on the inside of the turn due to the operation speed of the steering operation tool being too fast as the operation speed of the steering operation tool exceeds the speed limit. Is likely to become a large change rate exceeding the limit change rate, the rate of change of the opening degree of the valve unit can be limited to the limit change rate.

  As a result, when the steering operating tool is operated toward the limit operating angle, the operating speed is too high, and the rate of change of the opening degree of the valve unit related to the operating pressure of the braking device that brakes the traveling device inside the turn is It is possible to avoid the risk that the braking force applied to the traveling device inside the turning by the braking device inside the turning suddenly increases together with the operation pressure applied to the braking device inside the turning due to the excessive increase. As a result, it is possible to prevent an inconvenience that a shock is likely to occur due to a sudden increase in the braking force during the braking turn.

  Therefore, regardless of the operation speed of the steering operating tool, it is possible to smoothly switch to the braking turning state in which the traveling device inside the turning is braked.

The invention according to claim 3 of the present invention is the invention according to claim 1 or 2,
The steering operation tool until the steering operation tool reaches the limit operation angle from the set operation angle set near the limit operation angle based on the detection by the operation angle detector. The change rate of the opening degree of the valve unit obtained from the calculated operation speed is adopted as the set change rate.

  In the above invention, even when the steering operating tool reaches the limit operating angle, the opening degree of the valve unit related to the operating pressure of the braking device that brakes the traveling device inside the turn corresponds to the limit operating angle of the steering operating tool. From the opening to the maximum pressure setting opening, the rate of change of the valve unit opening obtained from the operating speed of the steering operating tool until the steering operating tool reaches the limit operating angle from the set operating angle. It will gradually change.

  As a result, at the stage where the steering operating tool is operated to the limit operating angle, for example, due to a change in the oil temperature or the like, the steering operating tool is operated to the limit operating angle. Due to the fact that the operating pressure on the braking device does not increase to a large operating pressure corresponding to the limit operating angle of the steering operating tool, the traveling device inside the turn does not reach the braking lock state, or due to individual differences in the braking device, etc. Then, although the operating pressure on the braking device inside the turning has increased to a large operating pressure corresponding to the limit operating angle of the steering operation tool, the traveling device inside the turning does not reach the braking lock state. Even if such a situation occurs, the control pressure of the turning control unit after operating the steering operating tool to the limit operating angle can be used to control the operating pressure on the braking device inside the turning regardless of the oil temperature change. The operating pressure should be set to a maximum operating pressure that is higher than the maximum operating pressure corresponding to the limit operating angle of the operating tool, or the large operating pressure required to obtain the braking lock state of the braking device with different individual differences. The rate of change can be gradually increased in a state where the rate of change is the same as the rate of change of the operating pressure when the steering operating tool is operated from the set operating angle to the limit operating angle.

  As a result, the braking force applied by the braking device inside the turning to the traveling device inside the turning to the large braking force necessary to obtain the braking lock state of the traveling device during braking turning makes the user feel uncomfortable due to a large change in the braking force. The vehicle can be gradually and reliably raised without being reminded by the driver.

  Therefore, the driver feels uncomfortable due to a large change in the braking force without causing the inconvenience of generating a shock due to the sudden increase in the braking force applied to the traveling device on the inner side of the braking. In a state where the steering operation tool is not operated, it is possible to avoid the possibility of inconvenience that the traveling device on the inner side of the turn does not reach the brake lock state in spite of operating the steering operation tool to the limit operation angle. As a result, the traveling state of the vehicle body can be reliably and smoothly switched to the small turning state in which the traveling device inside the turning is in the braking locked state by the operation to the limit operation angle of the steering operation tool.

It is a left view of a normal type combine. It is a top view of a normal type combine. It is a cross-sectional top view of a boarding operation part. It is a vertical left side view of a threshing apparatus. It is the schematic which shows the transmission structure of a normal type combine. It is the schematic which shows the transmission structure of a grain discharge apparatus. It is the schematic which shows the deceleration turning selection state of a driving | running | working transmission system. It is the schematic which shows the braking turning selection state of a driving | running | working transmission system. It is a hydraulic circuit diagram which shows the structure of a valve unit. It is a block diagram which shows a control structure. It is a figure which shows the relationship between the operating angle of a control lever, and the opening degree of the valve unit regarding the operating pressure of a braking device. It is a front view of a control lever. It is a top view of the principal part of a left operation panel. It is a figure which shows the relationship between a vehicle speed and the chaff opening of a chaff sheave.

  Hereinafter, as an example of an embodiment for carrying out the present invention, an embodiment in which a turning operation structure for a work vehicle according to the present invention is applied to a normal combine that is an example of a work vehicle will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the ordinary combine exemplified in the present embodiment cuts an uncut grain culm to be harvested that is located in front of the machine body at the left side of the front end portion of the traveling vehicle body 1 during work traveling. The cutting and conveying device 2 that conveys rearward is connected so as to be movable up and down while extending toward the front of the traveling vehicle body 1. The left half of the traveling vehicle body 1 receives the harvested cereal grains conveyed by the harvesting and conveying device 2 and applies the handling process to the granulated part of the harvested cereal grains while conveying it backwards. A threshing device 3 for performing a sorting process is installed. A grain tank 5 that stores grains lifted from the bottom of the threshing device 3 via the bucket conveyor 4 is mounted on the rear half of the right half of the traveling vehicle body 1. The rear end portion of the threshing device 3 is connected with a slaughtering device 6 that shreds the scouring waste after the threshing process and discharges it to the outside. The grain tank 5 is equipped with a screw conveying type grain discharging device 7 for discharging the grains stored in the grain tank 5 to the outside of the machine. And these are configured to harvest rice, wheat or soybeans.

  As shown in FIGS. 1 to 3, the traveling vehicle body 1 is provided with a pair of left and right crawlers 9 as a pair of left and right traveling devices A at a lower portion of a vehicle body frame 8 configured by connecting a plurality of steel materials such as a square pipe material. ing. A boarding operation unit 10 with a cabin is formed at the front side portion of the right half of the vehicle body frame 8, and a water-cooled diesel engine (hereinafter referred to as the engine) is provided at a position below a driver seat 11 provided at the rear of the boarding operation unit 10. 12) and the like are deployed.

  As shown in FIGS. 1 to 5, the cutting and conveying device 2 is configured to turn uncut cereals into cereals to be harvested and cereals not to be harvested as the aircraft travels at the left and right ends of the front end. A pair of left and right dividers 13 are provided. A rotary reel 14 is disposed above the front part of the cutting and conveying apparatus 2 so that the tip of the harvested grain culm divided by the left and right dividers 13 is scraped back. A clipper-shaped cutting mechanism 15 that cuts the stock source side of the harvesting cereal is provided at the bottom of the cutting and conveying device 2, and the harvested cereal that has been cut by the cutting mechanism 15 is placed behind the cutting mechanism 15. An auger drum 16 is provided that gathers at a predetermined position in the left-right direction and then feeds back from the predetermined position. And immediately behind the predetermined location, a feeder 17 comprising a slat conveyor is provided for feeding and conveying the harvested cereals fed rearward from the predetermined location toward the mash input port (not shown) of the threshing device 3. doing.

  The cutting and conveying apparatus 2 is a left-right feeder drive shaft that also serves as an input shaft of the cutting and conveying apparatus 2 provided at the rear end of the feeder 17 by the operation of a hydraulic lifting cylinder 18 installed over the body frame 8 and the feeder 17. It swings up and down around 19 as a fulcrum. The raising / lowering cylinder 18 is actuated by cutting and raising / lowering the operating pressure applied to the lifting / lowering cylinder 18 by swinging the cross-reverse and neutral return type control lever 20 provided in the front right part of the boarding operation unit 10 in the forward / backward direction. It is possible to control by switching the operation state of a valve unit (not shown) for use. That is, the cutting and conveying device 2 can be moved up and down by swinging the control lever 20 in the front-rear direction, and the cutting height adjustment for changing the height position of the cutting mechanism 15 with respect to the harvest target culm is performed. Can do.

  As shown in FIGS. 1, 2, 4, and 5, the threshing device 3 is a threshing unit 3 </ b> A that performs a handling process on the harvested cereal grains supplied and conveyed by the feeder 17, and a selection obtained by the handling process in the threshing unit 3 </ b> A. A sorting unit 3B that performs a sorting process on the target processing object, and a collecting unit 3C that collects the processing object to be collected obtained by the sorting process are provided.

  The threshing unit 3A rotates clockwise in front view with a front and rear handling cylinder shaft 23 as a fulcrum in a handling chamber 22 formed by arranging a U-shaped receiving net 21 and the like in the front-rear direction in the upper part of the threshing device 3. By doing so, a bar-type handling cylinder 24 that performs handling on the harvested cereal meal from the feeder 17 is provided.

  The sorting unit 3B is a swing sorting device 25 that swings and sorts a workpiece leaked from the receiving net 21 while moving it backward, a tang 26 that supplies a sorting wind for precise sorting to the swing sorting device 25, a swing The auxiliary tang 27 for supplying the sorting air for the rough sorting to the sorting device 25 and the No. 2 tang for supplying the sorting air for the second sorting to the swinging sorting device 25 are provided.

  The swing sorting device 25 includes a sheave case 30 that swings back and forth by the operation of an eccentric cam-type swing drive mechanism 29 provided at the lower portion thereof. On the upper part of the sheave case 30, a rough sorting gren pan 31, chaff sheave 32, and stroller 33 are arranged in that order from the front end of the sheave case 30 toward the rear. In the lower part of the sheave case 30, a fine pan 34, a fine sheave 35, and a second chaff sheave 36 for sorting the second product are arranged so as to be connected to each other in that order.

  The collection unit 3C includes a first collection unit 37 that collects the single-grained grains that have leaked from the front side of the swing sorting device 25 as the first thing below the swing sorting device 25, and a swing sorting device. The second collection unit 38 that collects the grain with branch branch and bifurcated grains that have leaked from the rear side of 25 as the second item is arranged so as to be lined up and down in that order.

  At the bottom of the number 1 collection unit 37, a number 1 transport screw 39 that transports the number 1 item flowing down to the bottom to the right is provided. At the bottom of the second collecting unit 30, a second conveying screw 40 is arranged for conveying the second item flowing down to the bottom to the right. At the right end of the No. 1 conveying screw 39, a bucket conveyor 4 for pumping the No. 1 item conveyed by the No. 1 conveying screw 39 to a supply port (not shown) provided in the upper part of the grain tank 5 is linked and connected. ing. The right end of the second transport screw 40 is interlocked with a screw transport type second reduction mechanism 41 that performs a handling process again on the second object transported by the second transport screw 40 and returns and transports it to the rough sorting grain pan 31. It is connected.

  As shown in FIG. 1, FIG. 2 and FIG. 6, the grain discharging device 7 is a grain tank that stores grains stored in the grain tank 5 by a carry-out screw 43 arranged in the front-rear direction at the bottom of the grain tank 5. 5 to the rear of the bottom. Moreover, the grain which the carrying-out screw 43 carried out is pumped up by the lifting screw conveyor 44 interlocked with the carrying-out screw 43. Then, the discharge screw conveyor 46 connected to the upper end portion of the lifting screw conveyor 44 through the relay screw conveyor 45 carries out the grains lifted by the lifting screw conveyor 44 to the outside of the machine.

  As shown in FIGS. 5 and 6, the power from the engine 12 is generated by a belt-type first transmission 47, a hydrostatic continuously variable transmission (hereinafter referred to as HST) 48 equipped as a main transmission, and It is transmitted to the left and right crawlers 9 via a traveling transmission system 50 built in a transmission case (hereinafter referred to as a T / M case) 49. Further, it is transmitted to the carp 26 through a belt-type second transmission device 51. Further, it is transmitted to the grain discharging device 7 via a belt tension type discharging clutch 52 or the like.

  As shown in FIGS. 4 and 5, the power transmitted to the carp 26 is transmitted from the left end of the carp 26 to the sub-carp 27 and the second carp 28 via the belt-type third transmission device 53, and It is transmitted to the rejection shredding device 6 via the third transmission device 53 and the belt-type fourth transmission device 54. Further, the speed is transmitted from the right end of the carp 26 to the left and right idler shaft 56 via a belt-type first reduction device 55.

  The power transmitted to the idler shaft 56 is decelerated and transmitted from the left end portion of the idler shaft 56 to the first transport screw 39 and the second transport screw 40 via the belt-type second reduction device 57, and the second transport screw. 40 is decelerated and transmitted to the swing drive mechanism 29 of the swing sorting device 25 via a belt-type fifth transmission device 58. Further, it is transmitted from the left end portion of the idler shaft 56 to the handling cylinder 24 via a belt tension type threshing clutch 59 and a bevel gear type handling cylinder transmission device 60. Further, the power is transmitted from the left end portion of the idler shaft 56 to the feeder drive shaft 19 via the belt tension type cutting clutch 61.

  The power transmitted to the feeder drive shaft 19 is transmitted to the left and right first relay shaft 64 via the chain-type sixth transmission device 63, and the cutting mechanism is connected from the first relay shaft 64 via the mechanical linkage device 65. 15, and is transmitted from the first relay shaft 64 to the auger drum 16 via the chain-type seventh transmission device 66. Then, it is transmitted from the auger drum 16 to the rotary reel 14 via a chain-type eighth transmission device 67, a second relay shaft 68 facing left and right, and a belt-type continuously variable transmission 69.

  The feeder drive shaft 19 is transmitted with the reverse rotation power taken out from the bevel gear 70 for taking out the reverse rotation power provided in the barrel transmission device 60 through the reverse rotation shaft 71 in the left-right direction via the belt tension type reverse clutch 72. can do. From this configuration, when the harvesting and conveying device 2 is clogged with the harvesting and conveying device 2 during operation, the harvesting and conveying device 2 is operated by turning off the harvesting clutch 61 and turning on the reverse clutch 64. Reverse rotation drive can be performed, and this makes it easy to remove the harvested cereal meal and the like clogged in the harvesting and conveying apparatus 2.

  As shown in FIGS. 7 and 8, the traveling transmission system 50 includes a gear-type sub-transmission device 73 that shifts power after shifting by the HST 48 in two steps, a crawler corresponding to the power after shifting by the sub-transmission device 73. 9 includes a pair of left and right side clutches 74 that intermittently transmit to 9 and a pair of left and right turning units 75 that operate during turning. Each of the left and right side clutches 74 is configured to self-return to the connected state by spring bias.

  As shown in FIGS. 3, 7, and 8, each of the left and right turning units 75 has a front-rear swing type two-position switching type switch lever 77 provided in the left operation panel 76 of the boarding operation unit 10 in the front-rear direction. By switching the operation position by swinging, the decelerated turning selection state in which the power after the shift by the sub-transmission device 73 can be decelerated and transmitted to the corresponding crawler 9 at the time of turning traveling, and at the time of turning traveling are supported. The crawler 9 is configured to switch to a brake turning selection state in which the crawler 9 can be braked.

  Specifically, in each of the left and right turning units 75, when the switching lever 77 is operated to the rear deceleration turning position, the transmission shaft 78 slidable in the left-right direction is slid to the right and the transmission shaft 78 is moved. The first reduction gear 79 that is integrally provided on the left and right sides meshes with the second reduction gear 80 on the lower side in the transmission direction, and the braking gear 81 that is slidable in the left and right direction is provided on the left and right sides of the T / M case 49. By slidably displacing the plate 82 in the meshing release direction and releasing the meshing, the second reduction gear 80 is integrally formed with the drum 83 so that the reduction transmission to the corresponding crawler 9 by the operation of the multi-plate friction clutch 84 is formed. It switches to the decelerating turning selection state that can be interrupted (see FIG. 7).

  When the switching lever 77 is operated to the front braking turning position, the transmission shaft 78 is slid to the left, the first reduction gear 79 is disengaged from the second reduction gear 80, and the braking gear 81 is moved. Is engaged with the brake plate 82 of the T / M case 49 by sliding displacement in the meshing direction, thereby switching to the brake turning selection state in which the braking force for the corresponding crawler 9 can be adjusted by the operation of the friction clutch 84. It changes [see FIG. 8].

  As shown in FIGS. 9 to 12, the traveling vehicle body 1 is equipped with an electronic control unit (hereinafter referred to as ECU) 85 configured using a microcomputer having a CPU, an EEPROM, and the like. The ECU 85 detects an operation angle detector 86 that detects an operation angle θ from a neutral position (straight forward position) N in the left-right direction of the control lever 20 that functions as the steering operation tool B by swinging in the left-right direction. , A turning control unit 85A for controlling the operation of the turning valve unit 87 that changes the operating pressure for the left and right side clutches 74 and the left and right friction clutches 84 is provided.

  The operation angle detector 86 is a rotary potentiometer. The valve unit 87 is a hydraulic type that operates the corresponding side clutch 74 and the friction clutch 84, and is a pilot-operated direction switching valve 89 that switches the flow of oil to the pair of left and right turning cylinders 88, and the direction switching valve 89 is turned to the left turning cylinder. An electrically operated left solenoid valve 90 and a direction switching valve 89 for supplying pilot pressure to the direction switching valve 89 for supplying oil to the 88 and switching to the left supply state in which oil is discharged from the right turning cylinder 88. An electrically operated right solenoid valve 91 that supplies the directional switching valve 89 with pilot pressure for discharging oil from the left turning cylinder 88 and switching to the right supply state in which oil is supplied to the right turning cylinder 88. The supply pressure to the revolving cylinder 88 can be limited to the set pressure. An electric operation type high-speed response type solenoid valve 93 for adjusting a pilot pressure for changing a set pressure of the relief valve 92 and the variable relief valve 92, and a supply pressure from the hydraulic pump 94 is controlled to a set pressure to control each solenoid valve 91, A system pressure reducing valve 96 for supplying oil to a system circuit 95 including 92 and 93, and a sequence valve 97 for supplying oil from the hydraulic pump 94 to the direction switching valve 89 as the pressure on the system circuit side rises to a set value. And a low-pressure relief valve 98 that operates when the variable relief valve 92 reaches a closed state that completely closes the circuit, and the like. 74 and the left and right friction clutches 84 are configured to change the operating pressure.

  When the turning control unit 85A detects that the operation position of the control lever 20 is the neutral position N based on the detection of the operation angle detector 86, the turning control unit 85A stops energizing the left and right solenoid valves 90 and 91. Then, the left and right solenoid valves 90 and 91 are discharged, the duty ratio D of the pulse current supplied to the solenoid valve 93 is set to 0%, and the pilot pressure supplied from the solenoid valve 93 to the variable relief valve 92 is made zero. As a result, the direction switching valve 89 is brought into the discharge state, and the set pressure of the variable relief valve 92 is made zero. As a result, the operating pressure for the left and right side clutches 74 and the left and right friction clutches 84 becomes zero as well as the supply pressure for the left and right turning cylinders 88. As a result, the left and right side clutches 74 are in a connected state and the left and right friction clutches 84 are in a disconnected state, whereby the left and right crawlers 9 can be driven at a constant speed by the power after shifting by the auxiliary transmission 73. A straight running state can be obtained.

  When an operation from the neutral position N of the control lever 20 to the left turn operation region L on the left side is detected based on the detection of the operation angle detector 86, the left solenoid valve 90 is energized to discharge the left solenoid valve 90. By switching from the state to the supply state, the direction switching valve 89 is switched from the discharge state to the left supply state, and oil is supplied to the left turning cylinder 88. Thereafter, when it is detected based on the detection by the operation angle detector 86 that the control lever 20 reaches the turning reference angle θa in the left turning operation region L, the duty ratio D of the pulse current supplied to the solenoid valve 93 is changed from 0% to 0th. By changing to 1 set value Da (for example, 25%), the pilot pressure supplied from the solenoid valve 93 to the variable relief valve 92 is changed to the first set pressure Fa corresponding to the first set value Da. Is changed from zero to the first set pressure Fa. As a result, the operating pressure for the left side clutch 74 and the left friction clutch 84 increases to the first set pressure Fa together with the supply pressure for the left turning cylinder 88. Then, the left side clutch 74 switches from the connected state to the disconnected state, and the left friction clutch 84 starts to shift from the disconnected state to the connected state. As a result, transmission to the left crawler 9 can be interrupted, and a left gentle turning state in which the right crawler 9 is driven by power after shifting by the auxiliary transmission 73 can be obtained.

  Further, when an operation between the turning reference angle θa in the left turning operation region L of the control lever 20 and the limit operation angle θb set for turning control is detected based on the detection by the operation angle detector 86, the control lever 20 is detected. Becomes closer to the limit operating angle θb, the duty ratio D of the pulse current supplied to the solenoid valve 93 is increased from the first set value Da to the second set value Db (for example, 48%), and is variable from the solenoid valve 93. By increasing the pilot pressure supplied to the relief valve 92 from the first set pressure Fa toward the second set pressure Fb corresponding to the second set value Db, the set pressure of the variable relief valve 92 is changed to the first set pressure Fa. And the pressure value corresponding to the operation position of the control lever 20 between the first set pressure Fb and the second set pressure Fb. Thus, the operating pressure for the left side clutch 74 and the left friction clutch 84 as well as the supply pressure for the left side turning cylinder 88 is the difference between the turning reference angle θa and the limit operating angle θb in the left turning operation region L of the control lever 20. It changes to a value between the first set pressure Fa and the second set pressure Fb corresponding to the operation position. Then, as the control lever 20 is largely operated from the turning reference angle θa toward the limit operating angle θb in the left turning operation region L, the operating pressure applied to the left friction clutch 84 is maintained while the left side clutch 74 is maintained in the disconnected state. And the frictional force in the left friction clutch 84 increases. Thereby, in the deceleration turning selection state, the transmission rate of the power transmitted to the left crawler 9 after being decelerated by the turning unit 75 gradually increases, and in the braking turning selection state, the left turn The braking force applied from the unit 75 to the left crawler 9 gradually increases.

  Thereafter, when it is detected based on the detection of the operation angle detector 86 that the control lever 20 reaches the limit operation angle θb in the left turn operation region L, first, the duty ratio D of the pulse current supplied to the solenoid valve 93 is set to the second. By changing to the set value Db and changing the pilot pressure supplied from the solenoid valve 93 to the variable relief valve 92 to the second set pressure Fb, the friction clutch 84 completely connects the set pressure of the variable relief valve 92. It changes to the 2nd setting pressure Fb set to the pressure value required in order to obtain a connection state. As a result, the operating pressure for the left side clutch 74 and the left friction clutch 84 rises to the second set pressure Fb as well as the supply pressure for the left turning cylinder 88. Then, the left friction clutch 84 is switched to the connected state while the left side clutch 74 is maintained in the disconnected state. As a result, in the deceleration turning selection state, the left crawler 9 is driven by the power decelerated by the left turning unit 75 after shifting by the sub-transmission device 73, and the right crawler is driven by power after shifting by the sub-transmission device 73. The left crawler 9 is completely stopped by the braking force from the left turning unit 75 and the sub-transmission device 73 is operated. A left braking turning state in which the right crawler 9 is driven by the power after the shift can be obtained.

  Next, after a set time T (for example, 0.25 seconds) has elapsed since the arrival of the control lever 20 at the limit turning angle θb in the left turning operation region L is detected based on the detection of the operating angle detector 86, the solenoid The duty ratio D of the pulse current supplied to the solenoid valve 93 is adjusted so that the duty ratio D of the pulse current supplied to the valve 93 reaches a third set value Dc (for example, 100%) for setting the maximum pressure. As time elapses after the arrival at the limit operating angle θb is detected, the second set value Db is gradually changed from the second set value Db toward the third set value Dc at a preset set change rate. The pilot pressure supplied to the variable relief valve 92 is gradually increased from the second set pressure Fb toward the third set pressure Fc (preset maximum pressure) corresponding to the third set value Dc. Thus, the set pressure of the variable relief valve 92 is gradually increased from the second set pressure Fb to the third set pressure Fc, and the set time T is detected after the arrival of the control lever 20 at the limit operating angle θb is detected. After the elapse of time, the third set pressure Fc is reached. Thereby, at the stage where the control lever 20 is operated to the limit operation angle θb of the left turn operation region L, for example, due to the rise of the oil temperature, the control lever 20 is moved to the limit operation angle θb of the left turn operation region L. In spite of the operation, the operating pressure for the left friction clutch 84 does not increase to a large second set pressure Fb corresponding to the limit operating angle θb of the control lever 20, or due to individual differences of the friction clutch 84, etc. As a result, the left friction clutch 84 is completely connected even though the operation pressure for the left friction clutch 84 has increased to a large second set pressure Fb corresponding to the limit operation angle θb of the control lever 20. Even if inconvenience such as not reaching the state occurs, the control operation of the turning control unit 85A after operating the control lever 20 to the limit operation angle θb of the left turning operation region L, Regardless of the increase in the oil temperature, the operation pressure for the left friction clutch 84 is a large second set pressure Fb corresponding to the limit operation angle θb of the control lever 20, or the friction clutch regardless of the individual difference of the friction clutch 84. In a state where the change rate of the operation pressure is limited to the set change rate toward the third set pressure Fc set to be higher than the large operation pressure necessary to obtain the brake lock state of the crawler 9 by the operation of 84. Can be raised gradually. As a result, the left crawler 9 is not completely driven to decelerate in the deceleration turning selection state even though the control lever 20 is operated to the limit operation angle θb of the left turning operation region L, and in the braking turning selection state. It is possible to avoid the occurrence of inconvenience such as a brake lock state in which the left crawler 9 is not completely stopped without causing a shift shock or a brake shock due to a sudden increase in the operation pressure.

  On the other hand, when an operation from the neutral position N of the control lever 20 to the right turn operation region R on the right side is detected based on the detection of the operation angle detector 86, the right solenoid valve 91 is energized and the right solenoid valve 91 is energized. Is switched from the discharge state to the supply state, thereby switching the direction switching valve 89 from the discharge state to the right supply state and supplying oil to the right turning cylinder 88. Thereafter, when it is detected based on the detection of the operation angle detector 86 that the control lever 20 reaches the turning reference angle θa in the right turning operation region R, the duty ratio D of the pulse current supplied to the solenoid valve 93 is changed from 0%. By changing to the first set value Da, the pilot pressure supplied from the solenoid valve 93 to the variable relief valve 92 is changed to the first set pressure Fa corresponding to the first set value Da, and the set pressure of the variable relief valve 92 is changed. The pressure is changed from zero to the first set pressure Fa. As a result, the operating pressure for the right side clutch 74 and the right friction clutch 84 increases to the first set pressure Fa together with the supply pressure for the right turning cylinder 88. Then, the right side clutch 74 is switched from the connected state to the disconnected state, and the right friction clutch 84 starts to shift from the disconnected state to the connected state. As a result, transmission to the right crawler 9 can be interrupted, and a right gentle turning state can be obtained in which the left crawler 9 is driven by the power after shifting by the auxiliary transmission 73.

  Further, when an operation between the turning reference angle θa in the right turning operation region R of the control lever 20 and the limit operation angle θb set for turning control is detected based on the detection by the operation angle detector 86, the control lever As 20 approaches the limit operating angle θb, the duty ratio D of the pulse current supplied to the solenoid valve 93 is increased from the first set value Da to the second set value Db, and the solenoid valve 93 changes to the variable relief valve 92. By increasing the supplied pilot pressure from the first set pressure Fa toward the second set pressure Fb corresponding to the second set value Db, the set pressure of the variable relief valve 92 is set to the first set pressure Fa and the second set pressure. The pressure value is changed to the pressure value corresponding to the operation position of the control lever 20 between the pressure Fb. Thus, the operation pressure for the right side clutch 74 and the right friction clutch 84 as well as the supply pressure for the right rotation cylinder 88 are the turning reference angle θa and the limit operation angle θb in the right turning operation region R of the control lever 20. It changes to a value between the first set pressure Fa and the second set pressure Fb corresponding to the operation position between. Then, as the control lever 20 is operated from the turning reference angle θa toward the limit operating angle θb in the right turning operation region R, the right side clutch 74 is maintained in the disengaged state and the operation to the right friction clutch 84 is performed. The pressure increases and the frictional force in the right friction clutch 84 increases. Thereby, in the deceleration turning selection state, the transmission rate of the power that is decelerated by the turning unit 75 and transmitted to the right crawler 9 gradually increases, and in the braking turning selection state, the right turning unit From 75, the braking force applied to the crawler 9 on the right side gradually increases.

  Thereafter, when it is detected based on the detection of the operation angle detector 86 that the control lever 20 reaches the limit operation angle θb in the right turn operation region R, first, the duty ratio D of the pulse current supplied to the solenoid valve 93 is set to the first value. 2 By changing to the set value Db and changing the pilot pressure supplied from the solenoid valve 93 to the variable relief valve 92 to the second set pressure Fb, the set pressure of the variable relief valve 92 is completely connected to the friction clutch 84. It changes to the 2nd setting pressure Fb set to the pressure value required in order to obtain the connection state to perform. As a result, the operating pressure for the right side clutch 74 and the right friction clutch 84 rises to the second set pressure Fb as well as the supply pressure for the right turning cylinder 88. As a result, the right friction clutch 84 is switched to the connected state while the right side clutch 74 is maintained in the disconnected state. As a result, in the deceleration turning selection state, the right crawler 9 is driven by the power decelerated by the right turning unit 75 after shifting by the sub transmission 73, and the left crawler is driven by power after shifting by the sub transmission 73. The right crawler 9 is completely stopped by the braking force from the right turning unit 75 and the sub-transmission device 73 is used. A right braking turning state in which the left crawler 9 is driven by the power after the shift can be obtained.

  Next, a pulse to be supplied to the solenoid valve 93 after a set time T has elapsed since the arrival of the control lever 20 in the right turning operation region R upon reaching the limit operation angle θb based on the detection of the operation angle detector 86. The lapse of time after detecting the arrival of the duty ratio D of the pulse current supplied to the solenoid valve 93 to the limit operating angle θb of the control lever 20 so that the current duty ratio D reaches the third set value Dc. At the same time, the pilot pressure supplied from the solenoid valve 93 to the variable relief valve 92 is gradually changed from the second set value Fb to the third set value Dc from the second set pressure Fb. By gradually increasing the pressure toward the third set pressure Fc corresponding to the third set value Dc, the set pressure of the variable relief valve 92 is changed from the second set pressure Fb to the third set pressure Fc. Is gradually increased to reach the third set pressure Fc after a set time T has elapsed since the arrival of the control lever 20 at the limit operating angle θb is detected. Thus, at the stage where the control lever 20 is operated to the limit operation angle θb of the right turn operation region R, for example, due to the rise in oil temperature, the control lever 20 is operated to the limit operation angle of the right turn operation region R. Despite the operation up to θb, the operating pressure on the right friction clutch 84 does not increase to a large second set pressure Fb corresponding to the limit operating angle θb of the control lever 20, or the individual difference of the friction clutch 84 Although the operating pressure on the right friction clutch 84 has increased to a large second set pressure Fb corresponding to the limit operating angle θb of the control lever 20, the right friction clutch 84 is completely Even if inconvenience such as not reaching a proper connection state occurs, the control operation of the turning control unit 85A after operating the control lever 20 to the limit operation angle θb of the right turning operation region R Regardless of the increase in the oil temperature, the operation pressure for the right friction clutch 84 is a large second set pressure Fb corresponding to the limit operation angle θb of the control lever 20, or the friction clutch regardless of the individual difference of the friction clutch 84. In a state where the change rate of the operation pressure is limited to the set change rate toward the third set pressure Fc set to be higher than the large operation pressure necessary to obtain the brake lock state of the crawler 9 by the operation of 84. Can be raised gradually. As a result, the right crawler 9 is not completely driven to decelerate in the deceleration turning selection state even though the control lever 20 is operated to the limit operation angle θb of the right turning operation region R. Thus, it is possible to avoid the occurrence of inconvenience such as the brake crawler 9 in which the right crawler 9 is not completely stopped without causing a shift shock or a brake shock due to a sudden increase in operating pressure.

  That is, in the reduced speed turning selection state, the first reduction gear 79, the second reduction gear 80, and the friction clutch 84 provided in each of the left and right turning units 75 constitute a reduction gear 99 for reduction turning [FIG. 7]. When the control lever 20 is operated from the neutral position N to either the left or right turning reference angle θa in this decelerated turning selection state, by the control operation of the turning control unit 85A based on the detection of the operation angle detector 86 at this time, The opening degree of the valve unit 87 relating to the operating pressures of the left and right side clutches 74 and the left and right speed reducers 99 (friction clutch 84) corresponds to the operating direction and the operating angle (turning reference angle θa) from the neutral position N of the control lever 20. The opening can be changed. Thereby, while maintaining both the left and right reduction gears 99 in a non-transmission state (disengagement state of the friction clutch 84) and maintaining the side clutch 74 on the outside of the turn that does not correspond to the operation direction of the control lever 20, The side clutch 74 inside the turn corresponding to the operation direction of the control lever 20 can be switched from the connected state to the disconnected state. As a result, transmission to the crawler 9 inside the turn is cut off, and a slow turning state in which the crawler 9 outside the turn is driven by the power after the shift by the auxiliary transmission 73 can be obtained.

  Thereafter, when the control lever 20 is operated from the turning reference angle θa to the limit operating angle θb, the left and right side clutches 74 and the left and right speed reducers are controlled by the control operation of the turning control unit 85A based on the detection of the operation angle detector 86 at this time. The opening degree of the valve unit 87 relating to the operating pressure of 99 can be changed to an opening degree corresponding to the operating direction and operating angle (limit operating angle θb) from the neutral position N of the control lever 20. Thereby, the side clutch 74 outside the turning that does not correspond to the operation direction of the control lever 20 is maintained in the connected state, and the side clutch 74 that corresponds to the operation direction of the control lever 20 is maintained in the disconnected state. The reduction device 99 outside the turning that does not correspond to the operation direction of the control lever 20 is maintained in the non-transmission state, and the reduction device 99 inside the rotation corresponding to the operation direction of the control lever 20 is switched from the non-transmission state to the transmission state. Can do. As a result, the crawler 9 inside the turning is driven by the power decelerated by the reduction device 99 inside the turn after the shift by the auxiliary transmission 73, and the crawler 9 outside the turning is driven by the power after the shift by the sub transmission 73. A deceleration turning state can be obtained.

  In addition, the opening degree of the valve unit 87 related to the operating pressures of the left and right side clutches 74 and the left and right speed reducers 99 is controlled by the control operation of the turning control unit 85A after operating the control lever 20 to the limit operating angle θb. Can be gradually changed at a preset change rate so as to reach an opening for setting the maximum pressure after a set time T has elapsed since reaching the limit operating angle θb. Thereby, at the stage where the control lever 20 is operated to the limit operation angle θb, for example, due to the rise in the oil temperature, the control lever 20 is operated to the limit operation angle θb, but the inside of the turn The crawler 9 inside the turning is not completely decelerated because the operating pressure on the decelerating device 99 does not increase to a large second set pressure Fb corresponding to the limit operating angle θb of the control lever 20, or individual differences of the decelerating device 99 For example, the crawler 9 on the inner side of the turn is in spite of the fact that the operating pressure on the speed reducer 99 on the inner side of the turn has increased to a large second set pressure Fb corresponding to the limit operation angle θb of the control lever 20. Even if inconveniences such as not being completely decelerated drive occur, the turning control unit 85A after the operation of the control lever 20 to the limit operation angle θb causes the inside of the turn. Regardless of the rise in oil temperature or the like, the crawler is operated by the second set pressure Fb corresponding to the limit operating angle θb of the control lever 20 or the operation of the speed reducer 99 having different individual differences regardless of the rise in the oil temperature. It is possible to gradually increase the change rate of the operation pressure to the maximum pressure set higher than the large operation pressure required to obtain 9 complete deceleration drive states, etc., with the change rate of the operation pressure limited to the set change rate it can.

  As a result, the operating pressure for the speed reducing device 99 on the inner side of the turning is gradually increased to a large operating pressure necessary to completely drive the crawler 9 on the inner side of the turning, regardless of an increase in the oil temperature or individual differences of the speed reducing devices 99. Therefore, while adopting an inexpensive valve that does not have a pressure compensation function or a temperature compensation function, a deceleration turning state can be achieved without incurring a shift shock due to a sudden increase in operating pressure. You can definitely get it.

  On the other hand, in the brake turning selection state, the braking gear 81, the brake plate 82, and the friction clutch 84 included in the left and right turning units 75 constitute the braking device 100 for braking turning (see FIG. 8). When the control lever 20 is operated from the neutral position N to the left or right turning reference angle θa in this braking turning selection state, the turning control unit 85A based on the detection of the operation angle detector 86 at this time performs the control operation. The opening degree of the valve unit 87 related to the operating pressure of the left and right side clutches 74 and the left and right braking devices 100 (friction clutch 84) corresponds to the operating direction and operating angle (turning reference angle θa) from the neutral position N of the control lever 20. The opening can be changed. Thereby, while maintaining both the left and right braking devices 100 in an unbraking state (disengaged state of the friction clutch 84) and maintaining the side clutch 74 on the outer side of the turn that does not correspond to the operation direction of the control lever 20, The side clutch 74 inside the turn corresponding to the operation direction of the control lever 20 can be switched from the connected state to the disconnected state. As a result, transmission to the crawler 9 inside the turn is cut off, and a slow turning state in which the crawler 9 outside the turn is driven by the power after the shift by the auxiliary transmission 73 can be obtained.

  Thereafter, when the control lever 20 is operated from the turning reference angle θa to the limit operating angle θb, the left and right side clutches 74 and the left and right braking devices are controlled by the control operation of the turning control unit 85A based on the detection of the operation angle detector 86 at this time. The opening degree of the valve unit 87 relating to the operating pressure of 100 can be changed to an opening degree corresponding to the operating direction and operating angle (limit operating angle θb) from the neutral position N of the control lever 20. Thereby, the side clutch 74 outside the turning that does not correspond to the operation direction of the control lever 20 is maintained in the connected state, and the side clutch 74 that corresponds to the operation direction of the control lever 20 is maintained in the disconnected state. The braking device 100 inside the turning corresponding to the operation direction of the control lever 20 is switched from the non-braking state to the braking state while the braking device 100 outside the turning not corresponding to the operation direction of the control lever 20 is maintained in the non-braking state. Can do. As a result, the left crawler 9 is completely stopped by the braking force from the braking device 100 inside the turning, and the braking turning state in which the crawler 9 outside the turning is driven by the power after the shift by the auxiliary transmission 73 is obtained. Can do.

  In addition, the opening degree of the valve unit 87 related to the operating pressures of the left and right side clutches 74 and the left and right braking devices 100 is controlled by the control operation of the turning control unit 85A after operating the control lever 20 to the limit operating angle θb. Can be gradually changed at a preset change rate so as to reach an opening for setting the maximum pressure after a set time T has elapsed since reaching the limit operating angle θb. Thereby, at the stage where the control lever 20 is operated to the limit operation angle θb, for example, due to the rise in the oil temperature, the control lever 20 is operated to the limit operation angle θb, but the inside of the turn The crawler 9 on the inner side of the turn does not reach the braking lock state because the operating pressure on the braking device 100 does not increase to a large second set pressure Fb corresponding to the limit operating angle θb of the control lever 20, or the individual braking device 100 Due to the difference or the like, the crawler 9 on the inner side of the turn despite the fact that the operating pressure on the braking device 100 on the inner side of the turn has increased to a large second set pressure Fb corresponding to the limit operation angle θb of the control lever 20. Even if inconvenience occurs such that the vehicle does not reach the braking lock state, the control operation of the turning control unit 85A after operating the control lever 20 to the limit operation angle θb Thus, the operation pressure applied to the braking device 100 on the inner side of the turn is a large second set pressure Fb corresponding to the limit operation angle θb of the control lever 20 or the braking device 100 having different individual differences regardless of the rise in the oil temperature or the like. Gradually increase the change rate of the operation pressure to the maximum pressure set higher than the high operation pressure necessary to obtain the braking lock state of the crawler 9 by operation, while limiting the change rate of the operation pressure to the set change rate Can do.

  As a result, the operating pressure on the braking device 100 inside the turning is gradually increased to a large operating pressure necessary to obtain the braking lock state of the crawler 9 inside the turning, regardless of the rise in oil temperature or individual differences of the braking devices 100. Therefore, while adopting an inexpensive valve that does not have a pressure compensation function or a temperature compensation function, it is possible to maintain a braking turning state without causing a braking shock due to a sudden increase in operating pressure. You can definitely get it.

  As shown in FIGS. 9 to 12, the turning control unit 85 </ b> A reduces the speed reducing device inside the turning until the arrival of the control lever 20 at the limit operating angle θb is detected based on the detection by the operating angle detector 86. 99 or the duty ratio D of the pulse current supplied to the solenoid valve 93, which is the rate of change of the opening degree of the valve unit 87 with respect to the operating pressure of the braking device 100, so that the rate of change does not exceed a preset limit rate of change. The rate of change of the ratio D is limited.

  Specifically, the turning control unit 85A obtains the operation speed in the left-right direction of the control lever 20 based on the detection of the operation angle detector 86, and the obtained operation speed of the control lever 20 exceeds a preset speed limit. In this case, it is determined that the rate of change of the duty ratio D of the pulse current supplied to the solenoid valve 93, which increases as the operating speed of the control lever 20 in the left-right direction increases, exceeds a preset rate of change. Based on the above, the change rate of the duty ratio D of the pulse current supplied to the solenoid valve 93 is limited to the limit change rate.

  As a result, the operation speed when operating the control lever 20 toward the limit operation angle θb is too fast, and the rate of change of the duty ratio D of the pulse current supplied to the solenoid valve 93 becomes too large, so that the deceleration turning selection is performed. In this state, the operating pressure on the speed reducer 99 (friction clutch 84) on the inside of the turn increases rapidly, and the speed change shock is caused by the speed change of the speed reducer 99 on the inside of the turn from the non-transmission state to the transmission state. In the braking / turning selection state, the operation pressure for the braking device 100 (friction clutch 84) inside the turning increases rapidly, and the braking device 100 inside the turning rapidly changes from the non-braking state to the braking state. It is possible to prevent the occurrence of inconveniences such as braking shocks easily occurring due to switching. As a result, regardless of the operation speed of the control lever 20 in the left-right direction, the switching to the deceleration turning state in which the crawler 9 inside the turn is decelerated and the switching to the braking turning state in which the crawler 9 inside the turn is braked are smoothly performed. Can be done.

  As shown in FIGS. 10, 12, and 13, the left and right crawlers 9 can change the height position with respect to the vehicle body frame 8 by the operation of the corresponding left and right hydraulic rolling cylinders 101. The ECU 85 includes a rolling control unit 85B that controls the operation of the valve unit 102 for rolling control that changes the operation pressure for the left and right rolling cylinders 101. The control lever 20 includes a first left-up switch 103 for instructing to raise the left side of the traveling vehicle body 1, a first right-up switch 104 for instructing to raise the right side of the traveling vehicle body 1, and the horizontal position of the traveling vehicle body 1. A first horizontal switch 105 for instructing a return is provided. The left operation panel 76 includes a second left raising switch 106 for commanding the left side of the traveling vehicle body 1 to rise, a second right raising switch 107 for commanding the right side elevation of the traveling vehicle body 1, and the return of the traveling vehicle body 1 to the horizontal posture. A second horizontal switch 108 for instructing to move, a raising switch 109 for instructing raising of the traveling vehicle body 1, a lowering switch 110 for instructing lowering of the traveling vehicle body 1, and automatic rolling for maintaining the traveling vehicle body 1 in a preset rolling reference posture. An automatic switch 111 for commanding execution and stop of the control is provided.

  When the automatic rolling control is stopped, the rolling control unit 85B causes the first left raising switch 103 or the second left raising switch 106 to output a left raising command when the first left raising switch 103 or the second left raising switch 106 is pressed. During this time, the operation of the valve unit 102 is controlled so that the left rolling cylinder 101 extends and the left side of the traveling vehicle body 1 is raised. When the pressing operation of the first left raising switch 103 or the second left raising switch 106 is released and the first left raising switch 103 or the second left raising switch 106 stops outputting the left raising command, the left rolling cylinder 101 Controls the operation of the valve unit 102 so as to obtain a state of stopping the extension operation.

  While the automatic rolling control is stopped, while the first right raising switch 104 or the second right raising switch 107 outputs a right raising command by the pressing operation of the first right raising switch 104 or the second right raising switch 107, The operation of the valve unit 102 is controlled so that the right rolling cylinder 101 extends and the right side of the traveling vehicle body 1 rises. When the pressing operation of the first right up switch 104 or the second right up switch 107 is released and the first right up switch 104 or the second right up switch 107 does not output the right up command, the right rolling cylinder 101 is released. Controls the operation of the valve unit 102 so as to obtain a state of stopping the extension operation.

  When the first horizontal switch 105 or the second horizontal switch 108 outputs a horizontal return command by the pressing operation of the first horizontal switch 105 or the second horizontal switch 108 in the stop state of the automatic rolling control, the left and right corresponding rolling cylinders 101 The operation of the valve unit 102 is controlled so that a state where the traveling vehicle body 1 is lowered to the lowest position and becomes horizontal by the operation is obtained.

  When the automatic switch 111 outputs an execution command for automatic rolling control by the pressing operation of the automatic switch 111 in the stop state of the automatic rolling control, a state in which the traveling vehicle body 1 maintains the horizontal posture by the operation of the corresponding left and right rolling cylinders 101 is obtained. As described above, the operation of the valve unit 102 is controlled based on the output of the rolling sensor 112 that detects the rolling of the traveling vehicle body 1.

  While the automatic rolling control is being executed, while the first left raising switch 103 or the second left raising switch 106 outputs the left raising command by the pressing operation of the first left raising switch 103 or the second left raising switch 106, The operation of the valve unit 102 is controlled so that the left rolling cylinder 101 extends and the left side of the traveling vehicle body 1 rises. When the pressing operation of the first left raising switch 103 or the second left raising switch 106 is released and the first left raising switch 103 or the second left raising switch 106 does not output the left raising command, the rolling sensor at this time The rolling angle of the traveling vehicle body 1 obtained from the output of 112 is set as a new control target value, and the traveling vehicle body 1 maintains the new control target value (arbitrary rolling posture) by the operation of the corresponding rolling cylinders 101 on the left and right. The operation of the valve unit 102 is controlled based on the new control target value and the output of the rolling sensor 112 so as to obtain a state to perform.

  In the execution state of the automatic rolling control, while the first right raising switch 104 or the second right raising switch 107 outputs the right raising command by the pressing operation of the first right raising switch 104 or the second right raising switch 107, The operation of the valve unit 102 is controlled so that the right rolling cylinder 101 extends and the right side of the traveling vehicle body 1 rises. When the pressing operation of the first right up switch 104 or the second right up switch 107 is released and the first right up switch 104 or the second right up switch 107 does not output the right up command, the rolling sensor at this time The rolling angle of the traveling vehicle body 1 obtained from the output of 112 is set as a new control target value, and the traveling vehicle body 1 maintains the new control target value (arbitrary rolling posture) by the operation of the corresponding rolling cylinders 101 on the left and right. The operation of the valve unit 102 is controlled based on the new control target value and the output of the rolling sensor 112 so as to obtain a state to perform.

  When the first horizontal switch 105 or the second horizontal switch 108 outputs a horizontal return command by the pressing operation of the first horizontal switch 105 or the second horizontal switch 108 in the execution state of the automatic rolling control, the left and right corresponding rolling cylinders 101 After controlling the operation of the valve unit 102 so that the traveling vehicle body 1 is lowered to the lowest position and becomes horizontal by the operation, the traveling vehicle body 1 maintains the horizontal posture by the operation of the corresponding left and right rolling cylinders 101. The operation of the valve unit 102 is controlled based on the output of the rolling sensor 112 so as to obtain a state to perform.

  Regardless of whether the automatic rolling control is stopped or executed, while the raising switch 109 outputs an ascending command by the pushing operation of the raising switch 109, both the left and right rolling cylinders 101 are extended and operated. The operation of the valve unit 102 is controlled so as to obtain a state in which the whole rises. Then, when the raising switch 109 is released and the raising switch 109 does not output the raising command, the operation of the valve unit 102 is controlled so that both the left and right rolling cylinders 101 can stop extending. .

  Regardless of whether the automatic rolling control is stopped or executed, while the lower switch 110 outputs the lowering command by the pressing operation of the lowering switch 110, both the left and right rolling cylinders 101 are contracted and the traveling vehicle body 1 is The operation of the valve unit 102 is controlled so as to obtain a state where the whole is lowered. Then, when the pressing operation of the lowering switch 110 is released and the lowering switch 110 stops outputting the lowering command, the operation of the valve unit 102 is controlled so that a state where both the left and right rolling cylinders 101 stop the contraction operation is obtained. .

  As shown in FIG. 10, the boarding operation unit 10 is provided with a first left-up switch 103 and a first right-up switch 104 provided on the control lever 20 so as to command the vehicle body 1 to turn slowly to the right. A turn switch 103 and a changeover switch 113 that functions as a left slow turn switch 104 that commands a slow turn to the left of the traveling vehicle body 1 are provided.

  In a state where the first left raising switch 103 and the first right raising switch 104 function as the right gentle turning switch 103 and the left gentle turning switch 104, the right gentle turning switch 103 is moved to the right gentle by the pressing operation of the right gentle turning switch 103. While the turning command is being output, the operating pressure for the right side clutch 74 and the right friction clutch 84 rises to the first set pressure Fa, and the left side clutch 74 is maintained in the connected state while maintaining the left side clutch 74 in the connected state. The operation of the turning valve unit 87 is controlled so that the right turning state in which the clutch 74 is switched from the connected state to the disconnected state is obtained. When the pressing operation of the right gentle turning switch 103 is released and the right gentle turning switch 103 does not output the right gentle turning command, the operating pressures on the right side clutch 74 and the right friction clutch 84 are reduced to zero. The operation of the turning valve unit 87 is controlled so as to obtain a straight traveling state in which the left and right side clutches 74 are connected.

  Further, while the left gentle turning switch 104 outputs a left gentle turning command by the pressing operation of the left gentle turning switch 104, the operating pressures on the left side clutch 74 and the left friction clutch 84 are reduced to the first set pressure Fa. The operation of the valve unit 87 for turning is controlled so as to obtain a left gentle turning state in which the left side clutch 74 switches from the connected state to the disconnected state while maintaining the right side clutch 74 in the connected state. To do. When the pressing operation of the left gentle turning switch 104 is released and the left gentle turning switch 104 stops outputting the left gentle turning command, the operating pressure on the left side clutch 74 and the left friction clutch 84 decreases to zero. The operation of the turning valve unit 87 is controlled so as to obtain a straight traveling state in which the left and right side clutches 74 are connected.

  That is, the control lever 20 is set to the neutral position (straight forward position) by causing the first left raising switch 103 and the first right raising switch 104 provided in the control lever 20 to function as the right gentle turn switch 103 and the left gentle turn switch 104. When it is necessary to slightly correct the direction of travel along the uncut mushrooms to be harvested in the straight running position, the control lever 20 remains in the neutral position (straight running position). By pushing the right gentle turning switch 103 or the left gentle turning switch 104 with the finger of the hand holding the control lever 20, it is possible to easily correct the traveling direction in a direction along the unharvested grain culm to be harvested. it can.

  Further, when the rolling posture of the traveling vehicle body 1 needs to be changed in a state where the first left raising switch 103 and the first right raising switch 104 function as the right gentle turning switch 103 and the left gentle turning switch 104, The rolling posture of the traveling vehicle body 1 can be easily changed by pressing the second left raising switch 106 or the second right raising switch 107 provided on the left operation panel 76.

  As shown in FIGS. 4, 10, and 14, the chaff sheave 32 is configured to be movable so that the opening degree of the chaff can be adjusted by the operation of the electric chaff motor 114. The ECU 85 controls the operation of the chaff motor 114 on the basis of the output of the operation position detector 116 including a rotary potentiometer that detects the operation position of the main transmission lever 115 that enables the HST 48 to perform a speed change operation. A chaff opening control unit 85C that adjusts the chaff opening of the chaff sheave 32 is provided so that the chaff opening of the chaff sheave 32 increases as the speed increases and the chaff opening of the chaff sheave 32 decreases as the vehicle speed decreases.

  The chaff opening control unit 85C takes in the operation position of the main transmission lever 115 output from the operation position detector 116 as vehicle speed data a, and applies data b obtained by applying a low-pass filter with a first-order delay to the vehicle speed data a. It is configured to be used as data for adjusting the opening of the chaff (for controlling the chaff motor).

  Thereby, at the time of acceleration by the operation of the main transmission lever 115, the responsiveness of the control operation when increasing the chaff opening according to the acceleration can be increased, and at the time of deceleration by the operation of the main transmission lever 115 In, the responsiveness of the control operation when the chaff opening is reduced according to deceleration can be delayed. As a result, it is possible to improve the sorting efficiency and sorting accuracy in the rough sorting chaff sheave 32.

  Note that the chaff opening control unit 85C takes the operation position of the main transmission lever 115 output from the operation position detector 116 as the vehicle speed data a, performs a delay process for a simple set time t, and then performs a primary delay. It may be configured to be used as data c obtained by applying a low-pass filter and data for chaff opening adjustment (for chaff motor control) [see FIG. 14].

    [Another embodiment]

[1] The work vehicle may be a self-removing combine, a tractor, or a rice transplanter configured to perform a braking turn for braking the left and right traveling devices A.

[2] The work vehicle includes a pair of left and right front wheels and a rear wheel as a pair of left and right traveling devices A, and is configured to perform a braking turn by braking one of the left and right rear wheels. Also good. Alternatively, the pair of left and right traveling devices A may include a pair of left and right front wheels and a rear crawler, and may be configured to perform a braking turn by braking one of the left and right rear crawlers.

[3] As the steering operation tool B, a steering wheel or a pair of left and right steering levers may be employed. Further, the limit operation angle θb of the steering operation tool B may be the mechanical limit operation angle of the steering operation tool B.

[4] A hydraulic multi-plate brake or the like may be employed as the braking device 100.

[5] As the valve unit 87, an electromagnetic proportional type is adopted as the solenoid valve 93, and the current supplied to the solenoid valve 93 is changed to change the operating pressure of the speed reducing device 99 or the braking device 100 inside the turning. It may be configured such that the opening degree of the valve unit 87 changes. Further, an on-off valve that is electrically operated and has a high-speed response type is provided in the upper oil passage with respect to the direction switching valve 89, and the duty ratio D of the pulse current supplied to the on-off valve is changed to thereby reduce the reduction device 99 on the inner side of the turn. Alternatively, the opening degree of the valve unit 87 related to the operation pressure of the braking device 100 may be changed.

[6] In order to prioritize the responsiveness of the control operation to the operation of the control lever 20 in the turn control, the turn control unit 85A reaches the limit operation angle θb of the control lever 20 based on the detection of the operation angle detector 86. May be configured so as not to limit the rate of change of the opening degree of the valve unit 87 related to the operating pressure of the deceleration device 99 or the braking device 100 inside the turning.

[7] As indicated by the alternate long and short dash line in FIG. 11, when the turning control unit 85A detects that the control lever 20 has reached the limit operating angle θb based on the detection of the operating angle detector 86 in the deceleration turning selection state. The opening degree of the valve unit 87 (duty ratio D of the pulse current supplied to the solenoid valve 93) related to the operating pressure of the speed reducer 99 that decelerates the crawler 9 inside the turning is the opening degree (duty ratio) corresponding to the limit operating angle θb. It may be configured to control the operation of the valve unit 87 so as to change from Db) to the maximum pressure setting opening degree (duty ratio Dc) at once.

[8] In order to gradually change the opening of the valve unit 87 related to the operating pressure of the deceleration device 99 or the braking device 100 inside the turning from the opening corresponding to the limit operating angle θb to the opening for setting the maximum pressure. You may make it provide the operation tool which enables the setting change of the set setting change rate.

[9] As indicated by a two-dot chain line in FIG. 11, the turning control unit 85A determines the limit from the set operation angle θc set by the control lever 20 near the limit operation angle θb based on the detection by the operation angle detector 86. The operation speed of the control lever 20 until reaching the operation angle θb is obtained, and the change rate of the opening degree of the valve unit 87 related to the operation pressure of the speed reducer 99 or the braking device 100 inside the turn obtained from the obtained operation speed is set and changed. You may comprise so that it may employ | adopt as a rate.

[10] The control lever 20 until the control lever 20 reaches the limit operation angle θb from the set operation angle θc set near the limit operation angle θb based on the detection of the operation angle detector 86 by the turning control unit 85A. Based on the calculated operation speed and a preset operation reference speed, the higher the operation speed is, the higher the setting change rate is, and the slower the operation speed is than the operation reference speed. You may comprise so that it may correct | amend to the state where a setting change rate becomes small.

  The turning operation structure for a work vehicle according to the present invention can be applied to a work vehicle configured to perform a braking turn for braking one of the left and right traveling devices.

85A Turning control unit 86 Operation angle detector 87 Valve unit 100 Braking device A Traveling device B Steering operation tool θ Operation angle (steering operation tool)
θb Limit operating angle θc Setting operating angle

Claims (3)

A pair of left and right traveling devices, two hydraulically operated braking devices that brake the corresponding traveling devices, a valve unit that changes operating pressures on the two braking devices, and an operation angle of the steering operating tool are detected. An operation angle detector; and a turning control unit that controls the operation of the valve unit, wherein the turning control unit brakes a traveling device inside the turning based on the detection of the operation angle detector. Operation on the braking device that brakes the traveling device on the inside of the turn by controlling the operation of the valve unit so that the opening of the valve unit related to the operating pressure corresponds to the operating angle of the steering operating tool. In a turning operation structure of a work vehicle configured to change a pressure to an operation pressure corresponding to an operation angle of the steering operation tool and adjust a braking force applied to the traveling device inside the turn.
When the turning control unit detects that the steering operating tool has reached the limit operating angle based on the detection of the operating angle detector, the valve unit related to the operating pressure of the braking device that brakes the traveling device inside the turning is detected. A work vehicle configured to control the operation of the valve unit so that the opening gradually changes at a preset change rate from an opening corresponding to the limit operating angle to an opening for maximum pressure setting. Swivel operation structure.   Until the turning control unit detects that the steering operating tool has reached the limit operating angle based on the detection of the operating angle detector, the steering based on the detection of the operating angle detector. The operating speed of the operating tool is determined, and when the determined operating speed exceeds a preset speed limit, the rate of change of the opening degree of the valve unit related to the operating pressure of the braking device that brakes the traveling device inside the turn is determined in advance. 2. The turning operation structure for a work vehicle according to claim 1, wherein, when it is detected that a set limit change rate is exceeded, the change rate of the opening degree of the valve unit is limited to the limit change rate.   The steering operation tool until the steering operation tool reaches the limit operation angle from the set operation angle set near the limit operation angle based on the detection by the operation angle detector. The work vehicle turning operation structure according to claim 1 or 2, wherein a change rate of the opening degree of the valve unit obtained from the obtained operation speed is adopted as the set change rate.

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