JP2002000008A - Vertical motion-controller in tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to descend a lift arm down to the lower limit even in the state where an auto lever has been shifted to the shallower side when a rotary tiller is removed from a tractor, in a vertical motion controller which uses a position controlling valve. SOLUTION: The vertical motion controller is provided with a flexibility range-changing means having the following structure: the end of an inner wire of a sensor wire 37 for detecting vertical motions of a rear cover and a controlling lever 22b of a position controlling valve for vertical motion in the rotary tiller are mechanically interlocked and coupled with each other via a cooperation mechanism 38 of a linking structure having a slotted hole flexibility by a slotted hole 43; the position of the cooperation mechanism 38 is determined under interlocking with the attaching and detaching of the end of an inner wire to the cooperation mechanism 38 so that it can be movably controlled in the direction of the flexibility by the auto lever 32; and the range of the slotted hole flexibility is automatically shifted and changed so that, in the state where the tension of the sensor wire 37 does not act on the cooperation mechanism, the end of the slotted hole flexibility is extended in the descending direction side of the control lever 22b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical lifting and lowering control device configured to stably maintain a plowing depth by controlling a rotary tilling device connected to a rear portion of a tractor using a position control valve. About.

[0002]

2. Description of the Related Art As shown in FIG. 1, a rotary tilling device 3 is connected to a rear portion of a tractor main body 1 via a three-point link mechanism 2, and is hydraulically driven by a built-in lift cylinder 4 so as to be able to swing up and down. In an agricultural tractor that drives and raises and lowers the three-point link mechanism 2 with the lift arm 5, as a lifting and lowering control device that stabilizes the tillage depth by controlling the rotary tilling device 3 using a position control valve to raise and lower the rotary tilling device 3 as shown in FIGS. The structure shown in FIG. 17 has been previously proposed by the present applicant.

[0003] This elevation control device is configured to arbitrarily rotate an adjustment lever shaft 22 of a position control valve 6 for controlling the operation of a lift arm 5 by a position lever 31 that can swing back and forth around a fulcrum x in front of the position. The adjusting lever shaft 22 is automatically rotated based on the control mode and the vertical swing of the rear cover 34 attached to the rear part of the tilling cover 33 in the rotary tilling device 3, and can swing back and forth around the fulcrum x. The automatic plowing depth control mode for maintaining the plowing depth set by the auto lever 32 can be used properly.

The adjusting lever shaft 22 is urged to rotate downward (clockwise in the figure) by a spring (not shown), and the adjusting lever shaft 22 is connected to the adjusting lever shaft 22.
The height position of the lift arm 5 is determined by regulating the position of the lift arm 5 in the biasing rotation direction. The end of the inner wire 37b of the sensor wire 37 that detects the vertical swing of the rear cover 34 attached to the rear part of the tillage cover 33 in the rotary tillage device 3 is swingably supported around the fulcrum a so as to swing back and forth. The swing link 41 and the locking pin 44 provided on the adjustment lever 22b are connected to the lower end of the
2 and are mechanically interlocked. Further, a support link 46 which is pivotally supported by the body so as to be able to swing back and forth around a fulcrum b at the lower end while supporting the swing link 41 at the upper end.
The fulcrum 32 is operatively connected to the lever 32 via a link rod 47 so that the fulcrum a of the oscillating link 41 can be moved forward and backward by the forward and backward swings of the auto lever 32 around the fulcrum x.

FIG. 14 shows a state in which the automatic lever 3 is set to the position control mode.
2 is moved and set to a position of the automatic plowing depth control “OFF” near the lower limit in the operation range, and the position lever 31 is operated to an arbitrary plowing depth position. In this setting state, since the fulcrum a of the swing link 41 is largely moved forward and the operation link 42 is also displaced forward, the end of the inner wire 37b of the sensor wire 37 and the adjusting lever 22b are connected to the elongated hole. The adjustment lever 22b comes into contact with and follows the position lever 31 to determine its rotational position.

FIG. 15 shows a state in which the automatic cultivation depth control mode is set. In this case, the position lever 31 is set to move to the lower limit of the operation range, and the automatic lever 32 is set to an arbitrary cultivation depth. Operated to the position.
In this set state, the inner wire 37 b is operated according to the vertical swing position of the rear cover 34, which is converted into forward and backward movement of the operation link 42 via the swing link 41, and is engaged at the front end of the long hole 43. The position of the stop pin 44 is regulated, and thus the position of the adjustment lever 22b is determined.

That is, the operating link 42 is
With the auto lever 32 operated to the lower limit position so as not to interfere with the control lever b, the position lever 31 is swung back and forth, and the adjustment lever 22b urged to rotate downward is directly contacted with the lower lever. In this state, the height of the rotary tilling device 3 can be changed and adjusted arbitrarily, that is, so-called position control can be performed. In addition, in a state where the position lever 31 is operated to a lower limit position that does not interfere with the adjustment lever 22b. By changing the position of the support arm 46 by the auto lever 32 and moving the entire sensor wire 37 back and forth, the position control valve 6 is neutrally balanced with respect to the ground height of the rotary tillage device 3, that is, in the automatic tillage depth control. It is configured to change and adjust the target plowing depth.

[0008]

In the above configuration,
When the rotary tiller is removed from the tractor and the inner wire 37b of the sensor wire 37 is removed from the swing link 41, the free swing link 41 is swung up and swinged by the spring 45, and the operation link 42 is displaced forward. At this time, as shown in FIG. 16, when the auto lever 31 is operated to the lower limit position, the support link 46 swings forward, and the swing link 41 supported by the support link 46 also swings forward. Because of the movement, the operation link 42 is also largely displaced forward, and the long hole 43 provided for this is displaced forward. Therefore, the engagement pin 44 of the adjustment lever 22b is
3. It becomes possible to move freely in the forward direction, that is, in the descending direction, within the interchange of 3, and can move to the lowest position following the position lever 31, and lower the lift arm connected to the rotary tillage device to the lower limit. Can be.

However, as shown in FIG. 17, when the inner lever 37b is removed from the swinging link 41 and the auto lever 31 is operated to the "shallow" side,
Since the operation link 42 is not sufficiently displaced forward, the front end of the long hole 43 causes the engagement pin 44 to move forward (downward direction) even if the position lever 31 is operated downward.
The movement of the lift arm 5 cannot be lowered to the lower limit, because the movement of the lift arm 5 cannot be lowered following the position lever 31.

The present invention has been made in view of such a point, and when the rotary tilling device is removed from the tractor, the position of the automatic lever is maintained even when the auto lever is operated to the "shallow" side. The purpose is to enable the lift arm to be lowered to the lower limit by a lever.

[0011]

Means for Solving the Problems [Structure, operation and effect of the invention according to claim 1]

(Structure) According to a first aspect of the present invention, there is provided a tractor elevating control device, wherein an adjusting lever of a position control valve for elevating a lift arm is displaced in contact with the ascending side by the position lever. Mechanically interlockingly couples the inner wire end of the sensor wire for detecting the vertical swing of the rear cover attached to the rear part of the tillage cover in the device and the adjustment lever through a linkage mechanism having flexibility, The position of the linkage mechanism is configured to be movable and adjustable in the direction of the accommodation by the automatic lever for setting the target plowing depth, and when the automatic lever is moved near the lower limit in the operation range, the sensor is operated. The size of the flexibility of the linkage mechanism is set so that the inner wire end of the wire and the adjustment lever are insulated by the flexibility. The tractor lift control device configured to displace the link mechanism by a pulling operation of the sensor wire accompanying the upward swinging of the rear cover and to displace the adjustment lever in an ascending direction at an end in the interchange. In a state where the tension of the sensor wire does not act on the linking mechanism, the range of the accommodation is interlocked with the attachment / detachment of the inner wire end to the linking mechanism so that the end of the accommodation is extended toward the lowering side of the adjustment lever. Is automatically provided to change the range.

(Operation) According to the above configuration, when the rotary tilling device is removed and the end of the inner wire of the sensor wire is removed from the linking mechanism, the end of the flexibility is extended toward the downward direction of the adjustment lever, and the position control valve is turned off. The adjustment lever can be freely operated downward without interference by the linkage mechanism, and can be operated to an arbitrary lowered position by the position lever.

(Effect) Therefore, according to the first aspect of the present invention, when the rotary tilling device is removed from the tractor, the lift arm can be moved by the position lever even if the auto lever is operated to the "shallow" side. Was reduced to the lower limit, and operability was improved.

[Structure, operation and effect of the invention according to claim 2]

(Structure) According to a second aspect of the present invention, in the tractor elevating control device according to the first aspect of the present invention, the linking mechanism includes a swing link to which an inner wire end of a sensor wire is connected; An oscillating link and an operating link for linking the adjusting lever are provided, and a fulcrum of the oscillating link is configured to be movable and adjustable by an auto lever. The adjusting lever and the operating link form the flexibility. It is linked by a long hole and a locking pin that engages with the long hole.

(Operation / Effect) According to the above configuration, the swing link that swings around the fulcrum operates smoothly with less backlash at the fulcrum, and can function smoothly and smoothly over a long period of time. . In addition, the mechanical accommodation in the link mechanism can be configured to be simple and excellent in durability, and the intended function can be properly exhibited over a long period of time.

[Structure, operation and effect of the invention according to claim 3]

(Structure) According to a third aspect of the present invention, in the tractor elevating control apparatus according to the second aspect of the present invention, the elongated hole forming the accommodation is provided with an elongated slot portion at an end of the main slot portion. It is configured as a stepped long hole that is connected in a stepped manner.

(Operation / Effect) According to the above configuration, only by changing the relative position between the long hole and the locking pin, the size is not affected by the long hole insertion state for automatic plowing depth control and the operation of the auto lever. And the switching of the slot accommodation can be easily performed.

[Structure, operation and effect of the invention according to claim 4]

(Structure) According to a fourth aspect of the present invention, in the tractor elevating control device according to the third aspect of the present invention, when the end of the inner wire is connected to the swing link, the operation link is moved downward by its own weight. When the locking pin is positioned in the main slot portion by the movement and the end of the inner wire is detached, the operation link is lifted against the own weight by contacting and pushing up with the oscillating link that has been urged and oscillated. By displacing the locking pin, the locking pin is moved to the extended slot portion.

(Operation / Effect) According to the above configuration, the switching of the slot accommodation is performed by effectively utilizing the oscillating link which is oscillatingly displaced by the attachment / detachment of the end of the inner wire. , And can be implemented simply and inexpensively.

[Structure, operation and effect of the invention according to claim 5]

(Structure) According to a fifth aspect of the present invention, in the tractor elevating control device according to the second aspect of the present invention, the elongated hole for forming the accommodation is provided with a narrow elongated elongated hole at an end of the main elongated hole portion. In addition to forming the parts in a straight line,
The locking pin is configured as a stepped pin, and in a state where the inner wire end is connected to the swing link, the large diameter portion of the locking pin engages with the main elongated hole portion to form the inner wire end. When the is removed, the small diameter portion of the locking pin is configured to engage with the extended elongated hole portion.

(Operation / Effect) According to the above configuration, when the end of the inner wire is connected to the swing link, the locking pin can move to the elongated elongated hole portion, so that the automatic plowing depth control is performed. In the mode, the flexibility due to the long holes is not inadvertently increased, the inner wire is securely linked to the adjustment lever, and accurate automatic plowing depth control can be performed.

[Structure, operation and effect of the invention according to claim 6]

(Structure) According to a sixth aspect of the present invention, in the tractor elevating control apparatus of the tractor according to the second aspect of the present invention, the elongated hole forming the accommodation is provided with an extended elongated hole portion at an end of the main elongated hole portion. A state in which an inner wire end is connected to the oscillating link, and a traction member is formed to be connected in a straight line, and a stopping member for preventing the locking pin from moving to the elongated elongated hole portion is provided. In this configuration, the restraining member is located at the towing production position, and when the inner wire end is removed, the restraining member is retracted from the towing production position.

(Operation / Effect) According to the above configuration, when the inner wire end is connected to the swinging link, the locking pin is prevented from moving to the elongated elongated hole portion by the restraint member. In the cultivation depth control mode, the flexibility due to the long holes does not increase unintentionally, the inner wire is reliably linked to the adjustment lever, and accurate automatic cultivation depth control can be performed.

[Structure, operation and effect of the invention according to claim 7]

(Structure) In the tractor elevating control device according to the seventh aspect of the present invention, in the sixth aspect of the invention, the restraining member is elastically biased toward a towing production position.

(Operation / Effect) According to the above configuration, the restraint member is shifted to the restraint release position against the urging force in conjunction with the removal of the inner wire. In addition, the restraining member is stably held at the towing production position, so that the function of automatic tillage depth control is not impaired, and the desired function can be exhibited.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a rear side surface of an agricultural tractor configured for rotary plowing. In this agricultural tractor, a rotary tillage device 3 is connected to a rear portion of the tractor main body 1 via a three-point link mechanism 2, and a lift arm 5 hydraulically driven by a built-in lift cylinder 4 so as to be able to swing up and down. The point link mechanism 2 is driven up and down.

As shown in the control hydraulic circuit of FIG.
The operation of the single-acting lift cylinder 4 is controlled by a position control valve 6. The position control valve 6 includes a main spool 7, a lowering valve 8, a relief valve 9, an unload valve 10 , Etc., and the lift cylinder 4 and the position control valve 6 are connected via a falling speed adjusting valve 11.

The position control valve 6 is provided on one side of the upper part of the rear transmission case 17 of the tractor main body 1 and, as shown in FIG. Swingable link 2
Eccentric pins 22 connected to both ends of the connecting link 21 at the inner end of the adjusting lever shaft 22.
a and an eccentric pin 23a connected to the inner end of the feedback arm shaft 23 are locked and connected to each other.

As shown in FIG. 2, an adjusting lever 22b is fixed to the outer end of the adjusting lever shaft 22, and a feedback arm 23b is fixed to the outer end of the feedback arm shaft 23. The main link 7 is shifted upward or downward by pivoting the link 22 b about the engagement point between the feedback arm shaft 23 and the eccentric pin 23 a, and the main spool 7 is shifted through the lift cylinder 4. As a result, the lift arm 5 operates to drive up or lower its own weight. When the lift arm 5 operates, the operation is converted into rotation of the feedback arm shaft 23 via the feedback link 24 and the feedback arm 23b, and the main spool 7
When the feedback arm 23b is rotated to a predetermined rotation position corresponding to the rotation operation position of the adjustment lever 22b, the main spool 7 returns to the neutral position, and the elevating operation is stopped. . That is, the adjustment lever 22b
Is arbitrarily rotated to raise and lower the lift arm 5 to a position corresponding to the adjustment lever 22b.

In the vicinity of the front side of the adjustment lever 22b, a position lever 31 for setting the working height artificially and an auto lever 32 for setting a target plowing depth during automatic plowing depth control are arranged back and forth around the fulcrum x. A position control mode in which swing adjustment is possible and friction holding is possible at an arbitrary operation position, and first, the rotary tilling apparatus 3 is arbitrarily moved up and down by the position lever 31 will be described. In addition,
In this position control mode, as shown in FIG. 8, the automatic lever 32 is shifted to the position of the forefront automatic plowing depth control “OFF”.

The main spool 7 of the position control valve 6 is urged in a projecting direction, that is, a downward direction by a coil spring 25, and accordingly, the adjustment lever 22b rotates clockwise in FIGS. It is urged and contacts the position lever 21 from behind. Therefore, as the position lever 31 swings rearward (counterclockwise in the drawing), the adjustment lever 22b is turned against the urging force, and the lift arm 5 corresponds to the adjustment lever 22b. Raised to the position. Conversely, as the position lever 31 swings forward (clockwise in the figure), the rotationally biased adjustment lever 22b rotates following the position lever 31, and the lift arm 5 moves down to a position corresponding to the adjustment lever 22b. When the position lever 31 is operated to the forefront position, the position control valve 6 is not returned to the neutral position regardless of the feedback accompanying the lowering of the lift arm 5, and the lift arm 5 is moved to the mechanical lower limit. Thus, a state in which the weight can be lowered, that is, a floating state is provided.

Next, an automatic plowing depth control mode for stably maintaining the rotary tillage device 3 at the plowing depth set by the auto lever 32, and a plowing depth setting structure and an automatic plowing depth control mechanism related thereto will be described.

As shown in FIGS. 5 and 6, the rear end of the tilling cover 33 covering the rotor portion 3a of the rotary tilling apparatus 3 from above prevents the scattered soil during tilling and flattens the tilling marks. The rear cover 34 is provided so as to be able to swing up and down around the fulcrum y. An L-shaped link 35 is provided at a rear portion of the cultivation cover 33 so as to be rotatable around a fulcrum z. An interlocking link 36 is provided between one end of the L-shaped link 35 and the rear cover 34. As a result, with the vertical swing of the rear cover 34 around the fulcrum y, L
The shape link 35 is rotated, and the sensor wire 37 connected to the other end of the L shape link 35 is operated.

The sensor wire 37 is composed of a release wire. The rear end of the outer wire 37a is connected to and supported by the cultivation cover 33, and the inner wire 37
The rear end of “b” is connected to the other end of the L-shaped link 35. The sensor wire 37 extends to the tractor main unit 1 side, and is linked to the adjustment lever 22b of the position control valve 6 at the right portion of the rear transmission case 17 via a linking mechanism 38 as follows. Are linked.

As shown in FIG. 8, the outer wire 3
The front end of 7a is connected and supported by a support pin 39a rotatably attached to the rear end of a wire support fitting 39 fixed to the rear transmission case 17, and the front end of the inner wire 37b is moved around the upper fulcrum a. The swing link 41 is connected to a lower free end of the swing link 41 disposed to be able to swing back and forth, and furthermore, an intermediate portion of the swing link 41 and the adjustment lever 22b.
Are linked by an operation link 42. Further, the swing link 41 is biased by a spring 45 in a counterclockwise direction in the drawing, so that the inner wire 37b is constantly biased forward.

The operation link 42 is composed of a front half plate portion 42a and a rear half rod portion 42b. An elongated hole 43 formed in the flat plate portion 42a and a locking pin 44 provided on the adjustment lever 22b are front and rear. It is engaged and linked with flexibility in direction. Here, the long hole 43 is configured as a stepped long hole in which an extended long hole portion 43b extending forward is connected to the front end of the main long hole portion 43a for automatic plowing depth control so as to be one step lower. The entire operation link 42 swings downward by its own weight around the connection point with the swing link 41,
Normally, the locking pin 44 is located at the upper main slot portion 43a.

The swing link 41 is pivotally connected via a fulcrum a to a free end of a support link 46 which can swing back and forth around a lower fulcrum b. Are linked and connected by a link rod 47, and when the auto lever 32 is rocked back and forth,
The support link 46 swings in the same direction, and the fulcrum a of the swing link 41 is adjusted to move back and forth along an arc locus centered on the fulcrum b.

Next, the automatic plowing depth control operation according to the above configuration,
And the plowing depth adjustment operation will be described. In this automatic cultivation depth control mode, basically, as shown in FIG. 9, the position lever 31 is operated to the lowermost position of the front limit.

In the floating state where the position lever 31 is operated to the lowermost position and the auto lever 32 is operated to the foremost position where the automatic plowing depth control does not work.
The rotary tilling device 3 is lowered to the lower limit, and the rear cover 34 is received by the field scene and is in a state of being greatly lifted. At this time, the inner wire 37b of the sensor wire 37 is pulled largely rearward by the lifting of the rear cover 34, and the operation link 42 is also moved rearward, but the front end e of the main long hole portion 43a in the long hole 43 is locked. Pin 44
The adjustment lever 22b is pivoted to the lower side D without abutting interference.

In this state, when the auto lever 32 is moved rearward (shallow cultivation depth) and set to a certain cultivation depth position, the fulcrum a of the swing link 41 is moved rearward by the swing of the support link 46 rearward. , And the operation link 42 is moved backward. When the operation link 42 is moved rearward, the locking pin 44 is moved rearward at the front end of the main elongated hole portion 43a, and the adjustment lever 22b is forcibly rotated to the ascending side U, and the lift arm 5 The drive up operation is performed, and the rotary tillage device 3 is raised. The front end e of the main slot portion 43a
The operation pin 42 is inadvertently displaced upward due to the vertical movement of the fuselage, so that the locking pin 44 is slightly recessed so that the locking pin 44 slightly engages.
It has been avoided to shift to.

When the rotary tilling apparatus 3 moves upward, the rear cover 34 relatively lowers and swings, and the sensor wire 37 moves downward.
Of the inner wire 37b is loosened. Accordingly, the swing link 41 is swung forward by the spring 45, and the operation link 42 also moves forward. Operation link 42
Moves forward, the linking pin 44, which is locked to the front end of the long hole 43, also moves forward, and the rotation position of the feedback arm 23a and the position of the adjustment lever 22b with the lift of the lift arm 5 are balanced. In this state, the position control valve 6 enters the neutral state, and the raising operation of the rotary tilling device 3 stops. FIG. 9 shows a state in which the position control valve 6 is in a neutral balance. At this time, the rotary tillage device 3
The target plowing depth set by the auto lever 32 is maintained, and thereafter, the plowing depth control is automatically performed with this state as a reference state.

When the tilling operation is being performed in the above-described reference state, for example, when the front wheel of the tractor 1 climbs over a bulge in the field, or the rear wheel falls into a concave part of the field, and the body rises and tilts, The rotary tilling device 3 starts to be deeper than the target cultivation depth, and accordingly, the rear cover 34 is lifted and swung, and the inner wire 37 of the sensor wire 37 is moved.
As the b is pulled, the swing link 41 swings backward, and the operation link 42 moves backward.

Here, in the reference state, the adjusting lever 2
Since the link pin 2b is engaged with the front end of the long hole 43 of the operation link 42 and the adjustment lever 22b is held at the predetermined target cultivation depth position, the cultivation depth is increased as described above and the operation link is increased. When 42 moves backward, the adjustment lever 22b
Is rotated to the ascending side U beyond the target plowing depth position, and the rotary plow 3 is driven up. And the rear cover 3
When 4 is restored to the original posture, the lifting operation is stopped and the plow is returned to the original plowing depth.

Further, when the tilling operation is performed in the above-described reference state, for example, the rear wheel of the tractor 1 climbs up a bulge in the field, or the front wheel falls into a concave portion of the field, so that the body of the tractor 1 is inclined forward and downward. Then, the rotary tiller 3 becomes shallower than the target plowing depth.
Swings down, and the inner wire 37b of the sensor wire 37 is loosened.

When the inner wire 37b is loosened, the swing link 41 swings forward, and the operation link 42 also moves forward. As a result, the link pin 44, which is engaged with the front end of the long hole 43, can also move forward, and the adjustment lever 22b is urged and turned to the lower side D from the target plowing depth position, so that the rotary plow 3 is rotated. Lowers its own weight. Then, when the rear cover 34 is lifted up to the original posture and rocked, the lowering operation is stopped and the plow is returned to the original plowing depth.

As the automatic lever 32 is moved rearward and rearward, the position of the inner wire 37b that supports the locking pin 44 at the front end e of the main slot portion 43a of the slot 43 and supports the adjustment lever 22b. Is located at the rear, and the state where the rear cover 34 is swung down, that is,
A shallow tillage state will be set. Conversely, the more the auto lever 32 is adjusted to move forward, the more the main slot portion 43a
The locking pin 44 is supported by the front end e of the
The position of the inner wire 37b supporting b is located forward, and the state where the rear cover 34 is lifted, that is, the deep tilling state is set. Then, when the auto lever 32 is set to the foremost “off” position, contact interference between the front end e of the main elongated hole portion 43a and the locking pin 44 is avoided, and the rotary tilling device 3 is largely lowered and Even when the cover 34 is lifted to the maximum, it becomes impossible to support the adjusting lever 22b by contacting and supporting the locking pin 44 at the front end e of the main slot portion 43a, and the automatic plowing depth control is turned off. It is.

Here, the displacement of the support link 46 with respect to the unit operation amount of the auto lever 32 when the auto lever 32 is in the rear deep plowing depth is the same as the displacement when the auto lever 32 is in the front shallow plowing depth range. A linking rod 47 is provided corresponding to the swing phase of the auto lever 32 and the swing phase of the support link 46 so as to be smaller than the displacement amount of the support link 46 with respect to the unit operation amount of the auto lever 32.
According to this, in a shallow tillage area used for roughing, etc., it is not necessary to adjust the tillage depth very finely, and to roughly adjust the tillage depth, the amount of change in the target tillage depth relative to the unit operation amount of the auto lever 32 is required. The larger is the easier to handle.
Conversely, in a deep tillage area, it is often desirable to set the tillage depth with high accuracy. In this case, the smaller the change amount of the target tillage depth with respect to the unit operation amount of the auto lever 32, the more finely the tillage depth is adjusted. It becomes convenient.

During the tilling operation using the above-mentioned automatic tilling depth control, when the work traveling of one stroke is completed and reaches the ridge,
By operating the position lever 31 on the ascending side of the auto lever 32, the adjustment lever 22b is directly turned to the ascending side U by the position lever 31, and the rotary till device 3 is forcibly raised by the position control. Then, after the change of the aircraft direction at the bank is completed, the position lever 31 is turned off.
Is operated over the automatic lever 32 to the lowermost position, thereby returning to the original automatic plowing depth control state and allowing the lowering operation to the target plowing depth.

The rotary tillage device 3 in this embodiment
As shown in FIG. 5, the cultivation cover 33 is configured to be able to rotate forward and backward about the rotor axis c, and the position of the rear cover 34 can be changed depending on the working mode. Has become. That is, the rotary tilling device 3
An operation lever 51 that can swing back and forth around a fulcrum d and can be switched to and held at three positions is mounted on the upper part of the upper part, and an operation arm 52 that swings integrally with the operation lever 51 and a cultivation cover 33 are linked. In a normal tilling operation in which tilling is performed at a standard tilling depth, the operation lever 51 is adjusted to the rear “standard” position, the tilling cover 33 is moved forward, and the cultivating shallow tilling is performed. At the time of work, the operating lever 51 is adjusted to the middle “shallow-raised” position, the cultivation cover 33 is moved slightly backward, and the rear cover 34 is adjusted to be properly grounded. In the case of, the operation lever 51 is adjusted to the front "scratching" position, the cultivation cover 33 is largely moved rearward, and the rear cover 34 is adjusted so as to properly contact the ground.

When the rotary tilling apparatus 3 is lowered from the air to a predetermined plowing depth, the rear cover 34 droops greatly during the lowering operation to the field scene, and the position control valve 6 is largely operated to the lowering side. , The descending speed becomes faster. When the rotary tilling device 3 starts to act on the field scene, the rear cover 34 also starts to touch down and starts to be relatively lifted, and the amount of operation of the position control valve 6 on the lower side with the lifting of the rear cover 34 is small. And the descending speed becomes low. As a result, the overall descent operation time is reduced as compared with the case where the descent is performed at a low speed throughout,
It reaches the target plowing depth more accurately than when descending at high speed throughout.

From the three-point link mechanism 2 to the rotary tilling device 3
When the other work device is removed and the rotary tilling device 3 is removed, the sensor wire 37 is also removed. However, when the end of the inner wire 37b is removed from the swing link 41, as shown in FIG. 41 is a spring 4
5 swings counterclockwise and swings. At this time,
Bent portion f formed on rod portion 42b of operation link 42
Is pushed up by the swing link 41, and the entire operation link 42 is swung upward around a connection point with the swing link 41. As a result, the locking pin 44 of the adjusting lever 22b moves relatively downward with respect to the operation link 42 and shifts from the main slot portion 43a to the extended slot portion 43b. It is possible to rotate largely forward (downward direction) without receiving.

Therefore, when the rotary tilling device 3 is detached, as shown in FIG. 10, even if the auto lever 32 is operated at a shallow position, the slot accommodation is greatly extended forward. The position lever 3
When 1 is operated to the lowest position, the adjustment lever 22b follows the position lever 31 and pivots largely in the downward direction, so that the lift arm 5 can be lowered to the lower limit.

[Other Embodiments] The present invention can be modified and implemented in the following forms.

FIGS. 11 and 12 show another example of forming the accommodation. In this example, the slot 43 forming the accommodation is formed by connecting a small-width extended slot portion 43b linearly to the end of the main slot portion 43a, and the locking pin 44 is It is configured as a stepped pin supported so as to be able to move back and forth in the axial direction. When the inner wire 37b is connected to the swing link 41, the locking pin 44 is protruded by the spring 55, and the large-diameter portion 44a engages with the main elongated hole portion 43a, and the locking pin 44 Is prevented from moving to the extended slot portion 43b,
When the inner wire 37b is detached, the operating lever 56 is brought into contact with and oscillated by the oscillating link 41 urged forward by the spring 45, and the oscillating displacement is rotated via the operating wire 57. This is transmitted to the moving lever 58, whereby the locking pin 44 is retracted against the spring 55, and the small diameter portion 44b engages with the elongated elongated hole portion 43b, and the locking pin 44 engages with the elongated elongated hole portion 43b. The transition is allowed, and the range of the slot accommodation can be automatically switched by attaching and detaching the inner wire 37b, as in the above embodiment.

FIG. 13 shows still another example of forming the above-mentioned accommodation. In this example, the slot 43 forming the accommodation is formed by connecting an extended slot portion 43b of the same width linearly to the end of the main slot portion 43a in a straight line. A retracting member 59 is provided at the end of the pivoting member 41 so as to be freely rotatable. When the inner wire 37b is connected to the swing link 41, the restricting member 59 is retracted.
Is projected by the spring 60 to the overlapping position for pulling over the long hole 43 to prevent the locking pin 44 from moving to the extended long hole portion 43b, and when the inner wire 37b is removed, the spring 45 The operating lever 56 is brought into contact with and oscillated by the oscillating link 41 which is urged and oscillated forward, and the oscillating displacement thereof is controlled by the traction member 5
9, the restraining member 59 is rotated against the spring 60, is retracted from the towing position, and the locking pin 44 is allowed to move to the elongated slot 43b. As in the above embodiment, the range of the slot accommodation can be automatically switched by attaching and detaching the inner wire 37b.

As an accommodation in the linkage mechanism 38, it is also possible to form a long hole 43 in the adjustment lever 22 b and provide a linkage pin 44 in the operation link 42.

The flexibility in the link mechanism 38 can be formed at a link portion between the swing link 41 and the operation link 42.

The accommodation is not limited to the engagement structure between the long hole and the linking pin. For example, the accommodation can be constituted by a notch having a desired accommodation width and a pin engaging and contacting the notch. It is.

[Brief description of the drawings]

FIG. 1 is a side view of a rear part of a tractor.

FIG. 2 is a side view of a control valve operation unit.

FIG. 3 is a front view showing a position control valve and its operation unit.

FIG. 4 is a plan view showing a part of the link mechanism;

FIG. 5 is a side view of a rotary tillage device.

FIG. 6 is a plan view showing a linkage structure between a rear cover and a sensor wire.

FIG. 7 is a hydraulic circuit diagram for lifting and lowering.

FIG. 8 is a side view of the control valve operation unit in the position control mode.

FIG. 9 is a side view of the control valve operating unit in the automatic plowing depth control mode.

FIG. 10 is a side view of the control valve operation unit in a state where the rotary tillage device is removed.

FIG. 11 is a side view showing another embodiment of the accommodation range changing means.

FIG. 12 is a front view of another embodiment of the accommodation range changing means.

FIG. 13 is a side view showing still another embodiment of the accommodation range changing means.

FIG. 14 is a side view of a conventional control valve operation unit in a position control mode.

FIG. 15 is a side view of a conventional control valve operation unit in an automatic plowing depth control mode.

FIG. 16 is a side view of a conventional control valve operation unit in a state where a rotary tillage device is removed.

FIG. 17 is a side view of a conventional control valve operation unit in a state where a rotary plow is removed.

[Explanation of symbols]

 Reference Signs List 3 rotary tillage device 6 position control valve 22b adjustment lever 31 position lever 32 auto lever 33 tillage cover 34 rear cover 37 sensor wire 38 linking mechanism 41 swing link 42 operation link 43 slot 43a main slot portion 43b extension slot portion 44 Locking pin 44a Large diameter part 44b Small diameter part

Claims (7)

[Claims] An adjustment lever of a position control valve for lifting and lowering a lift arm is configured to be contacted and displaced upward by a position lever, and a vertical cover of a rear cover mounted on a rear portion of a tillage cover in a rotary tillage device. The end of the inner wire of the sensor wire for detecting the movement and the adjusting lever are mechanically interlocked via a linking mechanism having flexibility, and the position of the linking mechanism is set to an auto lever for setting a target plowing depth. When the auto lever is moved near the lower limit in the operation range of the auto lever, the inner wire end of the sensor wire and the adjustment lever are connected to each other by the adjustment lever. The coupling size of the linkage mechanism is set so as to be insulated by the above, and the tension operation of the sensor wire accompanying the upward swing of the rear cover is performed. In the tractor lifting / lowering control device configured to perform the displacement operation of the linkage mechanism to displace the adjustment lever in the ascending direction at the end of the accommodation, the tension control unit may be configured to perform the above-described operation in a state where the tension of the sensor wire does not act on the linkage mechanism. In accordance with the attachment / detachment of the end of the inner wire with respect to the linkage mechanism, the accommodation range changing means for automatically switching and changing the accommodation range is provided so that the end of the accommodation extends in the downward direction of the adjustment lever. A tractor lifting / lowering control device. 2. The swing mechanism according to claim 1, wherein the link mechanism includes a swing link to which an inner wire end of the sensor wire is connected, and an operation link that links the swing link and the adjustment lever. 2. The tractor according to claim 1, wherein a fulcrum is configured to be movable and adjustable by an automatic lever, and the adjusting lever and the operation link are linked by a slot forming the accommodation and a locking pin engaged with the slot. Lift control device. 3. The tractor according to claim 2, wherein the slot forming the accommodation is a stepped slot formed by connecting an extended slot to the end of the main slot in a stepped manner. Lift control device. 4. When the end of the inner wire is connected to the swing link, the locking pin is positioned in the main slot by the downward movement of the operating link due to its own weight, and the end of the inner wire is removed. In the state, the operating pin is displaced upward against its own weight by contacting and pushing up with the oscillating link that has been urged and oscillated, thereby shifting the locking pin to the elongated slot portion. Item 4. The tractor lift control device according to Item 3. 5. An elongated hole forming the accommodation is formed by connecting a narrow elongated hole portion linearly to an end of a main elongated hole portion in a straight line, and the locking pin is formed as a stepped pin. In the state where the inner wire end is connected to the swing link, the large diameter portion of the locking pin engages with the main elongated hole portion, and when the inner wire end is removed, the locking pin engages. 3. The lift control device for a tractor according to claim 2, wherein the small diameter portion of the pin is configured to engage with the elongated elongated hole portion. 6. An elongated hole forming the accommodation is formed by connecting an extended elongated hole portion to an end of a main elongated hole portion in a straight line, and the locking pin is shifted to the extended elongated hole portion. A restraining member for preventing contact is provided, and in a state in which the inner wire end is connected to the swing link, the restraining member is in a position for towing and in a state where the inner wire end is removed, 3. The tractor lift control device according to claim 2, wherein the restraint member is configured to retreat from the towing production position. 7. The tractor lifting / lowering control device according to claim 6, wherein the restraining member is elastically biased toward a towing production position.