JP2007064385A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve operability of a differential-lock device of a working vehicle such as agricultural tractor and the like. <P>SOLUTION: This working vehicle comprises a differential-lock operating means 36, 67 for operating or releasing differential-lock devices 37A, 37B, a revolving control means S for raising a working machine 12 or braking a rear wheel 3 at an inner side of revolving by detecting revolving motion of a car body, and lowering the working machine 12 and releasing the braking at the inner side of revolving in returning from revolving from revolving motion to rectilinear motion, and a control portion C for switching the devices 37A, 37B in an operating state to a differential-lock releasing side when the revolving motion of the car body is detected, and keeping the devices 37A, 37B in the operating state in returning from revolving. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a work vehicle in which a front wheel or a rear wheel is rotationally interlocked with a respective transmission system via a differential mechanism and is provided with a differential lock device, and facilitates interlocking of the differential lock device.

2. Description of the Related Art Conventionally, work vehicles such as tractors have been provided with a diff lock device that locks the differential action by a differential mechanism in the transmission system of a front wheel or a rear wheel, and this diff lock device is turned on and off by an energization output of a controller. ing. For example, Japanese Patent Application Laid-Open No. 10-181374 discloses control for smoothly turning by operating a diff lock of a front wheel when turning in a wet field (Patent Document 1).
JP 10-181374 A

  The control device of the above publication has a front wheel speed increasing device that transmits the front wheel at a higher speed than the rear wheel, and a front differential lock that fixes a front differential that is linked to the front wheel. The speed device is connected to the high speed position to prevent the front wheel diff lock clutch pawl from being damaged during the front wheel high speed transmission. This is a control to improve the turning performance in the super wet field such as scratching work, but the steering handle is provided with a steering sensor consisting of a potentiometer that detects this steering angle, and its output is input to the controller. When the cutting angle of 16 is in the 0 rotation region, the vehicle body 6 is set to the straight advance position A, and at a position of 0.5 rotation (half rotation), the differential mechanism provided on the front axle is automatically set to the automatic diff lock position. There is a disclosure of the configuration.

  However, there is no consideration on the point of releasing the diff lock or the diff lock operation again in automatic turning control such as operating the rear wheel brake inside the turning in accordance with the steering operation, and the problem of complicated operation remains.

In order to solve the above problems, the present invention has taken the following technical means.
In other words, the working vehicle is provided with the rotational power of the engine (6) transmitted to the left and right traveling devices (2, 3) via the differential device (50F, 50R) and the working machine (12) is movable up and down with respect to the vehicle body. In
A differential lock device (37A, 37B) for limiting the differential of the differential device (50F, 50R) is provided, and differential lock operating means (36, 67) for operating or releasing the differential lock device (37A, 37B) are provided.
The turning of the vehicle body is detected to raise the work machine (12) or brake the rear wheel (3) inside the turn, and when returning from turning to the straight running state, the work machine (12) is lowered to turn. A turning control means (S) for releasing the inner braking is provided,
When the turning operation of the vehicle body is detected, the activated differential lock device (37A, 37B) is switched to the differential lock release side, and the work vehicle is equipped with a control unit (C) that activates the differential lock device (37A, 37B) when returning to the turn. It was.

  According to the above configuration, the rotational power of the engine (6) is transmitted to the left and right traveling devices (2, 3) via the differential device (50F, 50R), and when the differential lock actuating means (36, 67) is operated, the differential lock is applied. The device (37A, 37B) is activated. At this time, the differential lock is released in conjunction with the turning control, or the operation is returned to the operating state again.

  Thus, in conjunction with the operation of the turning control means (S), the work implement (12) is automatically raised or the rear inner wheels of the turning are automatically braked, and the differential lock devices (50F, 50R) are released. At the same time, when the predetermined turning operation is completed and the vehicle returns to the straight traveling state again, the differential lock is actuated again and the operation is continued, so that the operation of the operator can be reduced and the operability can be improved. Further, forgetting to cut the differential lock device (37A, 37B) is prevented, and the steering operability is not impaired.

The present invention will be described below with reference to the drawings.
As shown in FIG. 1, the tractor 1 is a four-wheel drive vehicle equipped with a wheel-type travel device. The tractor 1 has an engine 6 mounted on the center upper portion of the engine mounting frame 4 at the front of the vehicle body. Is transmitted to the front wheels 2 and 2 on the left and right of the front of the aircraft and the rear wheels 3 and 3 on the left and right of the rear of the aircraft via a transmission mechanism in the transmission case 13. Further, when the handle 7 is rotated left and right, the left and right front wheels 2 and 2 are steered via a power steering device.

  Also, lift arms 8 and 8 that are turned up and down by a lifting cylinder 43 are provided at the rear part of the machine body. The front ends of the lift arms 8 and 8 and the intermediate portions of the lower links 9 and 9 for mounting the work machine are connected by lift rods 11 and 11, and are connected to the rear ends of the upper link 10 and the lower links 9 and 9. A ground work machine (rotary work machine 12 in the illustrated example) is connected, and the lift arms 8 and 8 are turned up and down to raise and lower the rotary work machine 12.

  As shown in FIG. 3, the rotational power of the engine 6 is input to the transmission case 13 through the main clutch 5a, and the power through the main clutch 5a is the driving power for driving the front wheels 2, 2 and the rear wheels 3, 3. And branching transmission to two systems of work machine power. The traveling system power is changed to a predetermined speed via a traveling transmission device 5e including a forward / reverse transmission portion 5b, an eight-stage main transmission portion 5c, and a high, middle and low three-stage sub-transmission portion 5d, and is then shifted from the drive pinion shaft 5f. This configuration is transmitted to the ring gear of the wheel differential device 50R and drives the left and right rear wheels 3, 3. The power shifted by the traveling transmission 5e is taken out by branching the drive pinion shaft 5f, taken out to the front side of the transmission case 13 via the four-WD switching device 5g, and passed through the front wheel transmission shaft 5h to the front axle. It is transmitted to the ring gear of the front wheel differential device 50F in the case and transmitted to the left and right front wheels 2 and 2.

  A differential lock device 37F, 37R for locking the differential action is provided between the differential shaft and the output shaft of the front and rear differential devices 50F, 50R, and the differential lock device 37F, 37R is turned on and off by the differential lock cylinders 37f, 37r. It has become.

  Specifically, as shown in FIG. 4, in the differential lock device 37R of the differential device 50R on the rear axle 78 side, the drive pinion of the drive pinion shaft 5f meshes with the ring gear 79 of the differential device 50R, and the pinion 81 on the differential pinion shaft 80 81, output-side pinions 82l and 82r meshing with the pinions 81 and 81, left and right output shafts 83l and 83r spline-fitted to the output-side pinions 82L and 82R, and the like. A differential case portion 84, which is fastened to the ring gear 79 and the differential pinion shaft 80, is supported by a differential metal 85. A clutch engagement portion 84a is formed at the end of the differential case portion 84, and the output shaft 83R is spline-fitted. Thus, a differential lock clutch 86 in the form of a clutch pawl is provided so as to be slidable in the axial direction.

  The differential lock clutch 86 is interlocked with a piston 88 via a thrust needle 87, and receives pressure oil introduced into the cylinder 89 on the outer periphery of the piston 88 via an oil passage 90 by a flange-shaped portion 88a of the piston 88. is there. By this pressure oil, the piston 88 moves forward against the spring 91, and the differential lock clutch 86 can be engaged with the clutch engaging portion 84a.

  When the differential lock clutch 86 is engaged with the clutch engaging portion 84a, the rotation of the ring gear 79 is transmitted to the left and right output shafts 83L and 83R, and the left and right output shaft rotations are in the same rotational state. The differential device 50F has the same configuration, in which pressure oil is simultaneously supplied to or discharged from the hydraulic cylinders of the front and rear differential devices 50F and 50R by the action of the single differential lock control valve 36. . Since the configuration can be simplified as compared with the case where the control valves are individually associated with each other, the cost can be reduced.

  When the ring gear 79 is supported and configured on the differential case portion 84, the ring gear 79 is sandwiched between the left and right differential case portions 84l and 84r and is fastened with bolts 84a. An inlay portion 84b that can fit 84r into the left differential case portion 84l is formed. Accordingly, it is possible to prevent misalignment in assembling due to the ring gear 79 being fixed with the left and right differential case portions interposed therebetween.

  The oil passage 90 is formed in the housing 92a portion of the brake mechanism 92, and a cylindrical piston 89 is formed at the central portion of the housing 92a portion. The piston return spring 91 is connected to the differential case metal 94. Therefore, the length in the axial direction of the output shaft 83R of the differential lock device 50R can be reduced, and the configuration can be made compact.

92l and 92r are brake devices for braking the left and right output shafts 83l and 83r, respectively, and 93 is a final reduction device.
The work machine system power branches and takes out the drive output to the main clutch 5a to the PTO shaft 14 protruding rearward from the rear surface portion of the transmission case 13 via the PTO forward / reverse switching device 5j and the PTO transmission device 5k. This configuration is taken out and transmitted to the rotary work machine 12.

  Further, as shown in FIG. 2, the main transmission unit 5c increases / decreases one step at a time by pressing the transmission up switch 47 and the transmission down switch 48 provided on the transmission lever 15 grip, and the sub transmission unit 5d A shift operation of the lever 15 shifts the height.

Next, the hydraulic configuration of the tractor 1 will be described with reference to FIGS.
The hydraulic pressure discharged from the hydraulic pump 16 is first branched to the left and right brake cylinders 19 and 19 via the brake valve 18 on the upper side of the circuit via the reduce valve 17. The brake mechanisms 92l and 92r are braked by adjusting the braking force by supplying and discharging pressure oil from the brake cylinders 19 and 19.

  Similarly, in order from the upper side of the circuit, it is branched to the clutch cylinder 22 for forward / reverse switching of the forward / reverse transmission unit 5b via the front / rear clutch control valves 21a, 21b, and the main transmission unit 5c is used for 1-2 speed switching. The first transmission control valve 23 is branched to the first transmission cylinder 24. Further, the second transmission control valve 26 for switching the 3-4 speed of the main transmission unit 5c is branched to the second transmission cylinder 27, and the auxiliary transmission control valve 28 for switching the height of the auxiliary transmission unit 5d is used for the auxiliary transmission. Branching to the cylinder 29, branching to the 2WD 4WD switching cylinder 32 via the 2WD 4WD switching control valve 31 for 2WD 4WD switching of the 4WD switching device 5g.

  Further, the PTO transmission control unit 33 branches to the PTO transmission cylinder 34 via the PTO transmission control valve 33 for switching the height of the PTO transmission device 5k, and through the differential lock control valve 36, the front wheel diff lock cylinder 37a for the front wheel diff device 50F, and the rear wheel The structure is branched to the rear wheel differential lock cylinder 37b for the differential device 50R. Therefore, the pressure oil is supplied to or discharged from the front / rear wheel differential lock cylinders with the single differential lock control valve 36.

  The hydraulic pressure from the hydraulic pump 16 is taken out for work implement control, sent to the horizontal cylinder 41 via the horizontal control valve 39 for work implement horizontal control, and the hydraulic pressure via the horizontal control valve 39 is raised and lowered by the work implement. It is configured to be sent to the left and right lifting cylinders 43 via control valves 42, 42. Reference numeral 13 denotes a return oil tank.

Next, based on FIG. 8 and FIG. 9, the structure of the control part C which consists of each controller 46 and 61 connected by the communication line is demonstrated.
As shown in FIG. 8, various switches and sensors are connected to the input side of the travel controller 46 as follows. That is, a shift up switch 47 that shifts the main transmission 5c step by step to the high speed side, a shift down switch 48 that shifts the main transmission 5c transmission step by step to the low speed side, and the shift position of the sub shift lever 15 are detected. A shift lever position sensor 49, a shift position sensor 51 for detecting the shift position of the main transmission portion 5c, an engine speed sensor 52, a clutch pedal depression switch 53 for the main clutch 5a, and a vehicle speed sensor 54 are respectively connected.

  Further, on the output side of the traveling controller 46, a solenoid 56 for operating the shift control valve of the main transmission unit 5c, a solenoid 57 for operating the control valve for switching forward / reverse switching of the forward / reverse transmission unit 5b, a controller for a meter panel 58 are connected to each other.

  As shown in FIG. 9, on the input side of the work machine controller 61, a lever position sensor 62 for detecting the lever position of the work machine lifting lever 44, a handle angle sensor 63, a brake depression detection switch (left) 64, Brake depression detection switch (right) 66, differential lock on / off switch 67 for turning on and off the front and rear wheel differential lock devices at the same time, turning control on / off switch for raising / lowering the rotary tiller 12 and turning on / off the PTO clutch when turning on the shore 68 are connected to each other.

  Further, on the output side of the work machine controller 61, a solenoid 69 for the work machine raising control valve, a solenoid 71 for the work machine lowering control valve, the flow control valve 18a in the brake valve 18 and the switching control valve 18b are operated. The solenoids 72s, 72l, 72r,..., A differential lock actuating control valve solenoid 73, a front wheel speed increasing control valve solenoid 74, and a front wheel constant speed control valve solenoid 76 are respectively connected.

In the control unit C of the tractor 1 configured as described above, various controls are executed as in the flowchart showing the outline of the control program shown in FIG.
When the power supply system of the tractor 1 is turned on, first, the detection values of various sensors and setting switches are read (step 101), then the shift control of the tractor 1 (step 102), and the diff lock control of the front and rear wheels (step 103). ), Turning control (step 104) is executed.

  Note that the execution of the turning control in step 104 is based on the turning control means S incorporated in the controller 61 (control unit C). That is, based on the turning operation of the turning control on / off switch 68, the detection means for detecting the predetermined turning state is operated to operate a predetermined hydraulic pressure switching valve to automatically raise the work implement and brake the brake mechanism inside the turning. When it is detected that the turning operation returns to the straight running state, the operation of lowering the work implement and releasing the brake is performed again (turning control means S).

  Further, in the differential lock control in step 103, based on the ON operation of the differential lock on / off switch 67, the solenoid of the differential lock control valve 36 as the differential lock operating means is turned on to supply pressure oil to operate the differential lock. When the solenoid is turned off, the differential lock is released.

Details of the shift control (step 102) of the tractor 1 will be described.
The traveling transmission device 5e including the main transmission unit 5c and the sub transmission unit 5d is configured to be capable of multi-stage transmission from 1 to 8 stages. The transmission lever 15 switches the sub transmission unit 5c between high speed and low speed, When the shift up switch 47 or the shift down switch 48 provided in the grip is turned ON once, the speed is increased or decreased by one step.

  When the speed change switch 47 is turned on while the traveling transmission 5e is shifted to the highest speed, i.e., 8 speeds, the gear shifts to the first speed, and the lowest speed, i.e., is shifted to the first speed. When the shift down switch 48 is turned on, the shift operation is performed at the eighth stage, thereby simplifying the shift operation.

  Further, when the shift up switch 47 and the shift down switch 48 are simultaneously turned on, the gear is shifted to a preset intermediate position, here, the fourth speed at any speed position from 1st to 8th. . Thus, it is possible to quickly move to the shift position intended by the operator while simplifying the configuration and simplifying the operation.

Details of the diff lock control in step 103 of FIG. 10 will be described based on the flowcharts of FIGS.
Based on FIG. 11, when the differential lock clutch 85 is OFF, that is, when the differential devices 50F and 50R are both inactive (step 201), the vehicle speed sensor 54, specifically, the front axle rotation speed Nf is detected. The detected rotational speed Nf is compared with a preset reference rotational speed Ns (step 202). When the rotational speed is equal to or higher than the predetermined rotational speed, the solenoid of the diff lock control valve 36 is kept OFF (step 203). If it is less than that, based on the ON operation of the diff lock switch 67 (step 204), the solenoid of the diff lock control valve 36 is turned ON, pressure oil is supplied to the cylinder 88 of the front / rear diff lock device, and the diff lock clutch 85 is turned ON. The differential lock state in which the left and right rotations are synchronized is set (steps 205 to 207). If comprised in this way, the differential lock | rock in a high-speed state will be restrained and it can operate safely according to handle | steering-wheel operation.

  FIG. 12 will be described. In FIG. 12, when the differential lock clutch 85 is ON, that is, when both the differential devices 50F and 50R are in operation (step 301), the front axle rotational speed Nf is detected based on the detection of the vehicle speed sensor 54, and this detected rotational speed Nf is preliminarily determined. The set reference rotation speed Ns is compared (step 302). When the rotation speed is less than the predetermined rotation speed, the solenoid of the diff lock control valve 36 is kept on (step 303). Based on the OFF operation of 67 (step 304), the solenoid of the diff lock control valve 36 is turned off, the pressure oil is discharged from the cylinder 88 of the front and rear diff lock device, and the diff lock clutch 85 is turned off (steps 305 and 306). Thereafter, the front axle rotational speed Nf is compared with the predetermined rotational speed Ns (step 307). When the rotational speed reaches less than the predetermined rotational speed, the operation of the differential lock switch 67 is awaited after the operation of the differential lock switch 67, and the differential lock clutch 85 is set to a predetermined value. It is turned on (steps 308 to 311). If comprised in this way, the differential lock | rock in a high-speed state will be restrained and it can operate safely according to steering wheel operation.

  According to FIG. 13, when the diff lock clutch is in an ON state (step 401) and the left and right rear wheels are braked by operating the brake pedal (step 402), the solenoid of the diff lock control valve 36 is turned on. The pressure oil is supplied to the cylinder 88 of the front / rear differential lock device, and the differential lock clutch 85 is turned off to release the differential lock (steps 403 to 405). Next, when the brake operation is released (step 406) and the diff lock switch 67 is turned on (step 407), the diff lock is turned on in the procedure of steps 408 to 410.

  If comprised in this way, when a right-and-left one side brake or both brakes simultaneous operation is performed by the purpose of turning or direction correction, since a differential lock state will be cancelled | released, it will prevent turning radius and making a farm field rough. In addition, when the brake operation is released, the differential lock state is not automatically restored and the differential lock switch 67 is waited for to enter the differential lock state. Therefore, an operation based on the operator's recognition can be prevented. .

  FIG. 14 shows an improvement of the diff lock control shown in FIG. That is, after the diff lock is released, the diff lock is not automatically restored and the diff lock is turned on, but the operation of the diff lock switch 67 is temporarily waited. However, in the turning control mode, the diff lock is automatically restored. In the figure, the procedure from step 501 to step 506 is the same as that from step 401 to step 406 in FIG. 13, but it is determined in step 507 whether or not it is the turning control mode. In the turning control mode, when the turning operation is detected by the steering handle operation amount, etc., the work equipment is automatically raised to brake the brake inside the turning, and the peripheral speed of the front wheels is increased to about twice that of the rear wheels. Is. Of these controls, a single operation may be performed.

  When it is determined in step 507 that the turning control mode is set, the diff lock is automatically turned ON. When it is determined in step 507 that the turning control mode is not set, the diff lock switch 67 is waited for to return to the diff lock state ( Step 511). If comprised in this way, automatic diff lock | rock return can be made in automatic turning mode, and the operativity can be aimed at. In the automatic turning mode, when the steering handle 7 returns to the straight traveling state, it automatically returns to the original working state. As a part of this, the steering handle 7 returns to the differential lock state.

  FIG. 15 shows a state in which the turning angle acceleration ω of the steering handle 7 is greater than or equal to a predetermined standard or the steering angle is equal to or greater than a predetermined standard. At the same time, the diff lock is released, and after that, when the turning is restored and the steering angle is within a predetermined range, the work implement is automatically lowered to release the turning inner brake. Note that the turning control mode selection switch is provided separately, and the turning control mode is set based on the switch operation.

A side view of a tractor. The perspective view of the transmission lever vicinity. Transmission structure diagram of the tractor. Sectional drawing of a rear-wheel differential apparatus part. The figure which shows the hydraulic circuit of a tractor. The figure which shows the hydraulic circuit of a tractor. The figure which shows the hydraulic circuit of a tractor. The block diagram which shows the connection state of the controller for driving | running | working. The block diagram which shows the connection state of the controller for working machines. The control flowchart. The control flowchart. The control flowchart. The control flowchart. The control flowchart. The control flowchart.

Explanation of symbols

C Control unit (controller)
S Turn control means 1 Tractor 2 Front wheel 3 Rear wheel 5c Main transmission 5d Sub transmission 6 Engine 7 Handle 15 Shift lever 36 Differential lock control valve (Diff lock actuating means)
67 Differential lock on / off switch 68 Turning control on / off switch

Claims (1)

  In a work vehicle in which the rotational power of the engine (6) is transmitted to the left and right traveling devices (2, 3) via the differential device (50F, 50R), and the work machine (12) is movable up and down with respect to the vehicle body. A differential lock device (37A, 37B) for limiting differential of the differential device (50F, 50R) is provided, and a differential lock operating means (36, 67) for operating or releasing the differential lock device (37A, 37B) is provided. When the turning operation is detected, the work machine (12) is raised or the rear wheel (3) inside the turning is braked, and when returning from the turning operation to the straight running state, the working machine (12) is lowered and A turning control means (S) for releasing braking is provided, and when the turning movement of the vehicle body is detected, the activated diff lock device (37A, 37B) is switched to the diff lock release side. Working vehicle having click device (37A, 37B) control unit to the operating state of the (C).

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