JP2010030511A - Tread changing device of working vehicle - Google Patents

Abstract

An object of the present invention is to prevent an unexpected high pressure from being applied to a piping system of a hydraulic cylinder in a configuration in which a tread of a work vehicle can be changed by driving a hydraulic cylinder.
SOLUTION: Left and right front wheels 5, 5 and left and right rear wheels 6, 6 or any one of treads are driven by a left hydraulic cylinder 34L and a right hydraulic cylinder 34R which are driven by operation of a left valve 43L and a right valve 43R. A tread changing apparatus for a working vehicle to be changed, wherein the left valve 43L and the right valve 43R are driven in a predetermined cycle for a short time even after the tread is changed to a set value. The configuration is as follows.
[Selection] Figure 9

Description

  The present invention relates to a tread changing device for a work vehicle such as an agricultural tractor, a riding management machine, or an aerial work vehicle.

The work vehicle can change the left-right distance, that is, the tread of both the front wheel and the rear wheel or one of the rear wheels according to the distance between the ridges in the field and the planting interval. For example, Japanese Patent Laid-Open No. 2000-301906 discloses a tread changing device that allows a rear wheel tread to be changed with a hydraulic cylinder in a work vehicle.
JP 2000-301906 A

  The tread changing device of the work vehicle determines how much the tread is set at the start of running, changes the tread of the rear wheel with the hydraulic cylinder while running, and keeps the changed tread constant with the hydraulic cylinder. The hydraulic cylinder and its piping continue to be under high pressure due to heat, and when the hydraulic oil becomes hot as it travels, the pressure above the set pressure is Oil leakage may occur in the hydraulic piping.

  Therefore, an object of the present invention is to prevent an unexpected high pressure from being applied to a piping system of a hydraulic cylinder in a configuration in which the tread of a work vehicle can be changed by driving a hydraulic cylinder.

The problems of the present invention are solved by the following technical means.
According to the first aspect of the present invention, the left and right front wheels (5), (5) and the left and right rear wheels (6), (6) or any one of the treads are connected to the left valve (43L) and the right valve ( 43R) In the tread changing device for a work vehicle that is changed by the left hydraulic cylinder (34L) and the right hydraulic cylinder (34R) driven by the operation of 43R), the left valve (43L) and the right valve ( 43R) is configured to be driven in a predetermined cycle for a short time, and is a tread changing device for a work vehicle.

  With this configuration, the left valve (43L) and the right valve (43R) are actuated for a short time in a predetermined cycle after changing the tread. Then, the left hydraulic cylinder (34L), the right hydraulic cylinder (34R), and the other piping communicate with the main hydraulic circuit, so the left hydraulic cylinder (34L), the right hydraulic cylinder (34R), and the piping The pressure is released and does not become high pressure due to the influence of heat.

  According to the second aspect of the present invention, the left and right front wheels (5), (5) and the left and right rear wheels (6), (6) or any one of the treads are connected to the left valve (43L) and the right valve ( 43R) In a tread changing device for a work vehicle that is changed by the left hydraulic cylinder (34L) and the right hydraulic cylinder (34R) driven by the operation of 43R), the tread is changed to a set value and then fixed by the lock device (40) and the left side The tread changing apparatus for a work vehicle is characterized in that the valve (43L) and the right side valve (43R) are configured to be driven in a predetermined cycle for a short time.

  In this configuration, after the tread is changed to the set value, the tread width is fixed by the lock device (40). After changing the tread, the left valve (43L) and the right valve (43R) are actuated for a short time in a predetermined cycle. Then, the left hydraulic cylinder (34L), the right hydraulic cylinder (34R), and the other piping communicate with the main hydraulic circuit, so the left hydraulic cylinder (34L), the right hydraulic cylinder (34R), and the piping The pressure is released and does not become high pressure due to the influence of heat.

  According to the first aspect of the present invention, the operator changes the tread at the start of work and starts the work. However, the operator operates the left valve (43L) and the right valve (43R) for a short time in a predetermined cycle after the tread change. Even if pressure is applied due to the influence of heat or overheating of the oil, unexpected changes in the tread width and oil leakage from the hydraulic piping system do not occur.

  According to the second aspect of the present invention, after the tread is changed to the set value, the tread width is fixed by the locking device (40), so that the tread width is changed when a large load is applied. Can be prevented. In addition, since the left valve (43L) and right valve (43R) are actuated for a short period of time after changing the tread, the tread width can be changed unexpectedly or hydraulic piping even if there is an effect of heat or pressurization due to oil overheating. No oil leaks from the system.

Hereinafter, an agricultural tractor tread changing apparatus will be described with reference to the drawings, using an embodiment of the present invention as a work vehicle.
As shown in FIG. 1, the tractor 1 is provided with an engine E in a bonnet 2 on the front side of the vehicle body, and a clutch housing that houses a main clutch and a transmission case 3 that houses a gear transmission at the rear of the engine E. Are connected to each other. Further, left and right rear axle cases 4 and 4 that can be tread-changed are provided on both left and right sides of the transmission case 3, and rear wheels 6 and 6 are provided on both left and right sides of the rear axle cases 4 and 4, respectively. A front axle case (not shown) is provided below the engine E so as to be able to roll around an axial center in the front-rear direction, and front wheels 5 and 5 are provided on both the left and right sides.

  Next, the periphery of the cockpit 7 of the tractor 1 will be described. As shown in FIG. 3, a meter panel 13 provided with an alarm buzzer 11 and a liquid crystal monitor 12 serving as a notification unit is provided behind the bonnet 2, and a steering handle 8 protrudes behind the meter panel 13. The left and right front wheels 5, 5 are steered.

  A shift lever 9 for switching the transmission in the transmission case 3 and a work implement lifting lever 10 are provided on the side of the cockpit 7 so as to project, and an operation position is detected at a rotating base of the work implement lift lever 10. A work implement lift lever sensor SE1 is provided, and a shift lever sensor SE6 for detecting the operation position of the shift lever 9 is provided. Further, a tread width adjustment dial SW1 and a tread adjustment on / off switch SW2, which will be described later, are provided near the guides of these levers, and these setting signals are transmitted to the controller 14 below the cockpit 7. .

  A cylinder case 22 having a lifting cylinder (not shown) for lifting the working machine is provided at the rear upper part of the transmission case 3. The lift arm 23 supported by the cylinder case 22 is rotated in the vertical direction by extending and contracting the piston of the lift cylinder (not shown), and the work machine 24 connected thereto is lifted and lowered.

  One of the lift arms 23 is provided with a lift arm angle sensor SE2 that detects the height of the work implement. The detection position of the work implement lift lever sensor SE1 of the work implement lift lever 10 and the rotation of the lift arm 23 are provided. The controller 14 is configured to switch the switching control valve for raising or lowering the work implement in the hydraulic circuit so that the dynamic setting position matches. In the illustrated example, a rotary work machine is connected as the work machine 24.

Next, the transmission configuration from the transmission case 3 to the rear wheels 6 and 6 will be described with reference to FIG.
A rear wheel differential mechanism 31 is provided in the center of the rear left and right sides of the transmission case 3, and left and right rear axle cases 4 and 4 are attached to the left and right sides of the transmission case 3, and the rear wheel differential is transmitted from the transmission shaft (not shown) of the transmission case 3. Power is transmitted to the mechanism 31. Brake disks 36 and 36 are attached to the left and right output shafts 31L and 31R of the rear wheel differential mechanism 31, and are operated independently by the left and right brake cylinders.

  Inner transmission cylinders 4a and 4a are pivotally mounted on the left and right inner portions of the left and right rear axle cases 4 and 4 so that they can only rotate and cannot move in the left and right directions, and left and right axle support cylinders 4b and 4b are disposed on the left and right outer parts. Is supported so as to be rotatable and movable in the left-right direction.

  The left and right ends of the left and right output shafts 31L and 31R and the inner ends of the inner transmission cylinders 4a and 4a are connected to the planetary gear device 37 (the sun gear 37a and the inner transmission cylinder 4a provided on the left and right output shafts 31L and 31R). 4a, and a ring gear 37c fixed to the inside of the left and right wheel support case 4). Further, rear wheel shafts 6a and 6a are mounted on the left and right axle supporting cylinders 4b and 4b, and the left and right inner transmission cylinders 4a and 4a and the rear wheel shafts 6a and 6a are spline-engaged to form a tread. It is configured so that power can be transmitted while adjusting.

  Further, tread hydraulic cylinders 34L and 34R for adjusting the tread are provided on the front side portions of the left and right rear axle cases 4 and 4, and are connected to the front ends of the cylinders 34L and 34R and the left and right axle supporting cylinders 4b and 4b. The left and right stroke sensors SE3 and SE3 that are pushed and pulled together with the expansion and contraction of the pistons of the cylinders 34L and 34R are arranged side by side.

  A lock device 40 is provided that can fix the left and right rear axle cases 4 and 4 and the left and right axle support cylinders 4b and 4b. The lock device 40 (provided on the left and right rear wheels 6 side) is composed of a lock plate 40a and a lock bolt nut 40b as shown in FIG. 5, and when tread adjustment is not performed, that is, work that does not require tread adjustment. In the machine, the distance between the rear wheels 6 and 6 is fixed so that the tread cannot be changed or adjusted.

  That is, the lock plate 40a is spanned between the left and right axle support cylinders 4b supporting the rear wheel 6 and the machine body side, and is fixed by the lock bolt nuts 40b. When the tread width is fixed, the left and right pipes connected to the left and right tread hydraulic cylinders 34L and 34R can be removed and used as the external hydraulic pressure of another work machine.

  When adjusting the tread of the left and right rear wheels 6, 6, loosen the lock bolt nut 40b and then adjust to the desired tread width. When the adjustment is completed, tighten the lock bolt nut 40b to tread the left and right rear wheels 6, 6. Keep the width unchanged. As a result, it is possible to prevent a load from acting on the left and right rear wheels 6 and 6 from leaking hydraulic fluid and inadvertently changing the tread width.

  A label plate 53 is attached to the lock plate 40a, a tread width is displayed on a scale 54 attached to the label plate 53, and an operator sitting on the cockpit 7 looks back and reads the end face position of the rear axle case 4 through the scale 54. And the tread width. When the widths of the rear wheels 6 attached to the left and right axle supporting cylinders 4b are different, the scale 54 is replaced or the scale 54 is provided with a scale corresponding to the wheel width. FIG. 19 shows the state when the tread width is extended and the scale 54 in detail.

  6 and 7 show the mounting structure of the piston 27 and the rod 26 in the cylinder 25. A threaded portion 28 is formed at the tip of the rod 26 and is screwed into the screw hole 30 of the piston 27 for mounting. A two-chamfered portion 30 sandwiched between spanners is formed on the screw portion 28, and a hexagonal hole 29 into which a hexagon wrench is inserted is formed on the opposite side of the piston 27 from the screw hole 30. The screw hole 30 and the hexagonal hole 29 do not penetrate. With this structure, the number of parts is smaller than in the prior art, the protruding portion is eliminated on the end surface of the piston 27, and the tip of the rod 26 does not hit the cylinder 25.

Next, the hydraulic circuit configuration of the tractor 1 will be described with reference to FIG.
The hydraulic pressure discharged from the hydraulic pump 41 is sent to the horizontal cylinder 44 that adjusts the rolling of the vehicle body of the tractor 1 via the external extraction valve 42a, the diversion valve 42b, and the rolling control valve 43. In addition, it is sent to the return-type left and right tread hydraulic cylinders 34L and 34R via the diversion valve 42b, the rolling control valve 43, the diversion valve 42c, the left and right zoom control valves 43L and 43R, and the double check valves 35L and 35R. is there. Although the check valve 47 is provided in the return path of the left and right zoom control valves 43L and 43R, a configuration in which the check valve 47 is not provided and the oil is returned directly to the oil tank 49 may be used.

Next, the tread change control of the controller 14 will be described with reference to the flowchart of FIG.
First, in step S1, the tread width adjustment dial SW1 is set to a desired toledo width, and the tread adjustment on / off switch SW2 is set to “ON”. At this time, the left and right width can be adjusted by the left tread adjustment switch SW3 and the right tread adjustment switch SW4. When traveling is started in step S2, the left and right zoom control valves 43L and 43R are actuated in step S3 to drive the tread hydraulic cylinders 34L and 34R so that the tread width becomes the set width at a slight speed.

  In step S4, it is determined whether the tread width has reached the set width. If YES, the operation of the left and right zoom control valves 43L, 43R is stopped in step S5, and the current toledo width is locked by the lock device 40 in step S6. Thereafter, for example, a time count of 30 minutes is performed in step S7, and the left and right zoom control valves 43L and 43R are operated for about 100 mm seconds in step S8. Step S7 may be performed when the oil temperature is increased by 3 to 5 °. The operation of the left and right zoom control valves 43L and 43R performs pressure replenishment or high pressure relief.

Steps S7 and S8 are repeated until the work is completed in step S9.
In this embodiment, the sub-con control circuit 48 is provided at the rear position of the left and right zoom control valves 43L and 43R. However, the sub-con control circuit 48 may be provided at the front position of the flow path.

  Further, the left and right zoom control valves 43L and 43R and the sub-computer control circuit 48 may be arranged in parallel, and either circuit may be operated by the switching valve. At this time, if the type of the switching valve is a priority valve that can be adjusted from zero flow rate, both the left and right zoom control valves 43L and 43R and the sub-computer control circuit 48 can be used simultaneously.

  Further, the check valves of the double check valves 35L and 35R may be used as a check valve 38 with a relief function shown in FIG. 11 to prevent the internal pressure of the tread hydraulic cylinders 34L and 34R from rising. In the check valve 38 with a relief function, a check poppet 52 is provided with a relief valve function by a spring 50 and a ball 51.

  Further, the double check valves 35L and 35R may be replaced with drained relief valves 55 in FIG. 11 to prevent the internal pressure of the tread hydraulic cylinders 34L and 34R from increasing. When the internal pressure of the tread hydraulic cylinders 34L and 34R rises, the check valves 56 and 57 are operated to move the spools 58 and 59 of the drained relief valve 55, and the high pressure oil is returned from the drain ports 60 and 61 to the oil tank 49. Prevent the rise.

Next, a control block configuration showing detection signal input and control signal output of the controller 14 will be described with reference to FIG.
The controller 14 includes a CPU that processes various signals, an EEPROM that stores various control programs, a RAM that detects signals and setting values, a timer, and the like. The input section includes a tread width adjustment dial SW1, a tread adjustment on / off switch SW2, a left tread adjustment switch SW3, a right tread adjustment switch SW4, a tread width enlargement adjustment switch SW5, a tread width reduction adjustment switch SW6, and a check mode switch SW7. A work implement lift lever sensor SE1, a lift arm angle sensor SE2, a left tread stroke sensor SE3, a right tread stroke sensor SE4, a vehicle speed sensor SE5, and a shift lever sensor SE6 are connected.

  Further, the tread control valves 43L and 43R for operating the tread left extending solenoid SL1, the tread left contracting solenoid SL2, the tread right extending solenoid SL3, the tread right contracting solenoid SL4, and the liquid crystal display unit 46 of the meter panel are connected to the output unit. is doing.

  Further, as shown in FIG. 13, the operation panel 13 of the tractor 1 includes a tread width adjustment dial SW1, a tread adjustment on / off switch SW2, a left tread adjustment switch SW3 for the left rear wheel 6, and a right for the right rear wheel 6. A tread adjustment switch SW4, a tread width enlargement adjustment switch SW5 that enlarges and adjusts the treads of the left and right wheels 6 and 6 simultaneously, and a tread width reduction adjustment switch SW6 that simultaneously reduces and adjusts the treads of the left and right wheels 6 and 6 are provided. The tread adjustment switch SW3, right tread adjustment switch SW4, tread width enlargement adjustment switch SW5, and tread width reduction adjustment switch SW6 are configured to be covered with a translucent cover C.

  Further, the liquid crystal display unit 46 of the meter panel 13 is provided with a scaled left display unit 46a for displaying the tread adjustment of the left wheel 6 and a scaled right display unit 46b for displaying the tread of the right wheel 6. The tread adjustment state of the rear wheels 6 and 6 is displayed.

Next, rear wheel tread adjustment control of the controller 14 will be described.
In this embodiment, in a tractor capable of adjusting the tread of the left and right rear wheels 6 and 6 by extending and contracting the left and right tread hydraulic cylinders 34L and 34R, the tread width adjustment dial SW1 for setting the tread width of the left and right rear wheels 6 and 6 is adjusted. On / off switch SW2 and left and right tread stroke sensors SE3 and SE4 for detecting the tread amount of the left and right rear wheels 6 and 6 are provided, and the left and right rear wheels 6 and 6 are adjusted to the tread designated position by the control output from the controller 14. Constitute.

  The tread adjustment on / off switch SW2 is configured as a rebound switch without a switch lock mechanism so that it can be set (holding on) or reset (holding off) each time the switch is pressed. Only when the tread adjustment on / off switch SW2 is in the on state, the left and right tread hydraulic cylinders 34L, so that the operation position of the tread width adjustment dial SW1 and the detection positions of the left and right tread stroke sensors SE3 and SE4 substantially coincide with each other. 34R is configured to be feedback controlled. If the engine E is at a high speed when the tread adjustment on / off switch SW2 is set to “ON”, the engine E is automatically rotated at a low speed for safety.

  When a switch that automatically adjusts the tread width is provided, when the automatic switch is turned on after the engine is started, the tread width is corrected to a set width by about 2 mm, for example, every 30 seconds.

  FIG. 14 shows the pressure reducing valve mechanism of the front wheel acceleration valve. A spool holder 66 is inserted into a hole formed in the valve main body 65. O-rings 67, 68, 69, and 70 are mounted on the outer periphery of the spool holder 66 to prevent oil leakage. A spring 74 and a spool 71 are held by a C-type retaining ring 72 inside the spool holder 66.

  FIG. 15 shows an improved configuration of the front wheel acceleration valve, wherein an O-ring 67 at the hole entrance of the valve body 65 is provided between the outer periphery of the spool holder 66 and the inner periphery of the hole, and an O-ring 70 at the tip of the spool holder 66. Is changed to an O-ring 73 provided between the end surface of the spool holder 66 and the bottom surface of the hole.

FIG. 16 shows an improved configuration of the front wheel speed increasing valve, in which the O-ring 73 of FIG.
FIG. 17 shows an improved configuration of the front wheel acceleration valve, wherein the O-ring 73 of FIG. 15 is composed of a seat 75 and an O-ring 76.

  FIG. 18 shows a structure in which a single oil passage penetrating the pilot oil passage 78 of the relief valve 77 and the pilot oil passage 80 of the pressure reducing valve 79 is used for easy processing.

It is a whole side view of an agricultural tractor. 1 is an overall rear view of an agricultural tractor. It is a front view of a meter panel. It is a cutting top view of the rear-wheel drive part in the rear part of a mission case. It is the fragmentary sectional view (b) and partial perspective view of a tread fixing device. It is a hydraulic cylinder expanded sectional view. It is a rod front end view of a hydraulic cylinder. It is a hydraulic circuit diagram. It is a flowchart figure of control. It is sectional drawing of a check valve. It is sectional drawing of a check valve. It is a control block diagram. It is a front view of a meter panel. It is sectional drawing of the front wheel speed-up valve of a prior art example. It is sectional drawing of the front wheel speed-up valve of another Example. It is sectional drawing of the front wheel speed-up valve of another Example. It is sectional drawing of the front wheel speed-up valve of another Example. It is sectional drawing of the front wheel speed-up valve of another Example. It is a partial front view.

Explanation of symbols

5 Front wheel 6 Rear wheel 34L Left hydraulic cylinder 34R Right hydraulic cylinder 40 Locking device 43L Left valve 43R Right valve

Claims (2)

  Left hydraulic pressure that drives the left and right front wheels (5), (5) and / or the left and right rear wheels (6), (6) or any one of the treads by operating the left valve (43L) and the right valve (43R). In a tread changing device for a work vehicle that is changed by a cylinder (34L) and a right hydraulic cylinder (34R), the left valve (43L) and the right valve (43R) are driven in a predetermined cycle for a short time even after the tread is changed to a set value. A tread changing device for a work vehicle, characterized in that it is configured to do so.   Left hydraulic pressure that drives the left and right front wheels (5), (5) and / or the left and right rear wheels (6), (6) or any one of the treads by operating the left valve (43L) and the right valve (43R). In a tread changing device for a working vehicle that is changed by a cylinder (34L) and a right hydraulic cylinder (34R), the tread is changed to a set value and then fixed by a lock device (40), and the left valve (43L) and the right valve (43R) are fixed. ) Is driven for a short time at a predetermined cycle.

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