JP6861122B2 - Tractor - Google Patents

Description

INDUSTRIAL APPLICABILITY According to the present invention, a three-point link mechanism connected to the rear portion of a vehicle body so as to be swingable up and down, and a hydraulic cultivating device attached to the three-point link mechanism are moved up and down together with the three-point link mechanism. The present invention relates to a tractor including a unit and a mechanical linkage unit for automatic lifting that converts a change amount of a traction load into a lifting operation amount and transmits the change amount to the lifting drive unit.

Examples of the tractor as described above include a draft adjustment lever for setting the tillage depth, a link mechanism (cylinder shaft, arm, etc.) that links the spool of the control valve to the draft adjustment lever, and a load detection member that swings back and forth according to the traction load. (Top link hinge) and a second link mechanism (draft feedback link mechanism) that links the spool of the control valve to the load detection member, etc., so that the traction load is determined by the depth setting of the draft adjustment lever. Some are configured to allow draft control to be maintained at (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-109802

In the above-mentioned tractors, for example, when performing tillage work by draft control in a standard field where the traction load is unlikely to increase due to the hardness of the soil and the fluctuation of the traction load is unlikely to be large, and the hardness of the soil, etc. In a field where the traction load tends to be large and the traction load fluctuates sharply, the tilling device such as a plow or subsoiler is moved up and down at a standard speed according to the traction load regardless of the case of performing the tilling work by draft control. It is configured to let you.
This causes the tiller to rise at a standard rate based on the rise in traction load, even if the traction load rises sharply.
Therefore, when the traction load rises sharply, the rise in the traction load cannot be suitably suppressed, and there is a risk of causing an engine stall due to the rise in the traction load.

That is, it is desired to be able to avoid an engine stall caused by an increase in the traction load even when the traction load suddenly increases.

As a means to solve the above problems
The tractor according to the present invention is a hydraulic type that vertically drives a three-point link mechanism connected to the rear portion of the vehicle body so as to be swingable up and down, and a tow-type tilling device attached to the three-point link mechanism together with the three-point link mechanism. The elevating drive unit and the mechanical linkage unit for automatic elevating that converts the amount of change in the traction load into the elevating operation amount and transmits it to the elevating drive unit.
The mechanical linkage unit includes a change amount conversion mechanism having a load detection member that swings back and forth according to a traction load transmitted via the top link of the three-point link mechanism, the change amount conversion mechanism, and the elevating drive unit. Equipped with a link mechanism that interlocks and connects
The change amount conversion mechanism has a swing member that is swingably supported by the load detection member and is interlocked and connected to the lift drive unit via the link mechanism, and swings back and forth of the load detection member. The load detection member uses the first conversion state in which the change amount of the traction load obtained by motion is converted into the elevating operation amount without amplifying it, and the change amount of the traction load obtained by the back-and-forth swing of the load detection member. It is possible to switch between the second conversion state, which is amplified by the relative swing between the swing member and the swing member, and then converted into the lifting operation amount.

According to this means, when a change occurs in the traction load in the cultivating work in which a traction type tillage device such as a plow or a subsoiler is attached to a three-point link mechanism, the load detection member changes according to the amount of change in the traction load at this time. In addition to swinging back and forth, the amount of change in the traction load is amplified by the relative swinging of the load detecting member and the swinging member. Then, the amount of change in the traction load after amplification is converted into an elevating operation amount and transmitted to the elevating drive unit.
As a result, the traction type tiller can be quickly raised and lowered according to the change in the traction load, and as a result, even when the traction load suddenly increases, the engine stall due to the increase in the traction load can be avoided. Can be done.

Further, since the load detection member and the swing member swing relative to each other, the amount of change in the traction load can be greatly amplified while narrowing the swing range of the load detection member and the swing member. As a result, the front-rear length of the space required for installing the change amount conversion mechanism having the load detection member and the swing member can be shortened.
As a result, it is possible to avoid an engine stall caused by a sudden increase in the traction load while suppressing an increase in the size of the vehicle body, which increases the overall length of the vehicle body.

As one of the means for making the present invention more suitable,
When pre-Symbol change amount conversion mechanism of the first conversion condition, the by integral oscillation of the load detection member and the swing member, the lifting drive as the lifting operation amount without being amplified variation of the traction load Informed to the unit
When the change amount conversion mechanism is in the second conversion state, the change amount of the traction load is amplified by the relative swing between the load detection member and the swing member, and the lift operation amount is used as the lift operation amount in the lift drive unit. Reportedly.

According to this means, for example, when tilling work with a plow or a subsoiler is performed in a standard field where the traction load is unlikely to be large due to the hardness of the soil and the traction load is not likely to fluctuate sharply, the operator changes the amount of change. When the conversion mechanism is switched to the first conversion state, the tiller such as a plow or subsoil can be moved up and down according to the traction load at a standard speed suitable for this field. As a result, it is possible to avoid engine stall due to an increase in traction load while performing draft control in which the change in plowing depth is gentle.
Further, for example, when performing tillage work with a plow or a subsoiler in a field where the traction load tends to be large due to the hardness of the soil and the traction load fluctuates sharply, the operator converts the change amount conversion mechanism into the second conversion mechanism. When switched to the state, the tiller such as a plow or subsoil can be moved up and down according to the traction load at a high speed suitable for this field. As a result, even when the traction load suddenly increases, it is possible to avoid an engine stall caused by the increase in the traction load.

As one of the means for making the present invention more suitable,
The mechanical linkage unit includes an operating tool for switching the change amount conversion mechanism between the first conversion state and the second conversion state.

According to this means, the operator can easily switch the change amount conversion mechanism between the first conversion state and the second conversion state by operating the operating tool.

As one of the means for making the present invention more suitable,
The change amount conversion mechanism includes a holding mechanism that urges the swing member to a predetermined posture with respect to the load detection member.
The operating tool includes a receiving member that moves between a non-receiving position and a receiving position.
When the receiving member is located at the non-receiving position, the receiving member deviates from the rocking region of the rocking member and does not receive the rocking member, so that the load detecting member and the rocking member Will swing integrally due to the holding action of the holding mechanism.
When the receiving member is located at the receiving position, the receiving member is located within the rocking region of the rocking member to receive the rocking member, whereby the load detecting member and the rocking member Relative swinging against the holding action of the holding mechanism is allowed.

According to this means, the change amount conversion mechanism is provided with a holding mechanism, and the operating tool is provided with a receiving member. When the receiving member is in the non-receiving position, the change amount conversion mechanism swings with the load detecting member. It is possible to obtain a first conversion state in which the member and the member swing integrally. Further, when the receiving member is in the receiving position, it is possible to obtain a second conversion state in which the relative swing between the load detecting member and the swing member is allowed in the change amount conversion mechanism.
As a result, it is possible to reliably switch between the first conversion state and the second conversion state of the change amount conversion mechanism while simplifying the configuration.

As one of the means for making the present invention more suitable,
When the receiving member is located at the receiving position, the load detecting member and the swinging member are integrally shaken by the holding action of the holding mechanism while the swinging member is not received by the receiving member. While moving and the rocking member is being received by the receiving member, relative swinging between the load detecting member and the rocking member against the holding action of the holding mechanism is allowed.

According to this means, even if the receiving member is located at the receiving position, until the amount of swinging displacement of the load detecting member based on the traction load reaches a predetermined amount received by the receiving member. Is transmitted to the elevating drive unit as an elevating operation amount without amplifying the change amount of the traction load because the load detecting member and the oscillating member oscillate integrally. When the amount of swing displacement of the load detection member exceeds a predetermined amount, the swing member is received by the receiving member and the load detection member and the swing member swing relative to each other, so that the amount of change in the traction load is increased. Is amplified and then transmitted to the elevating drive unit as the elevating operation amount.
As a result, in a work situation where the traction load slightly exceeds the set value and there is no risk of causing an engine stall, even if the change amount conversion mechanism is in the second conversion state, the elevating drive unit will be in the work situation at this time. A tiller such as a plow or subsoiler is driven up and down according to the traction load at a suitable standard speed.
Further, in a work situation where the traction load greatly exceeds the set value and the possibility of causing an engine stall is high, the elevating drive unit traction load of a tilling device such as a plow or a subsoiler at a high speed suitable for the work situation at this time. It is driven up and down according to.
As a result, even in a work situation where the traction load slightly exceeds the set value, the durability of the elevating drive unit is reduced due to the elevating drive unit driving the tilling device up and down at an unnecessarily high speed. While avoiding the risk, it is possible to avoid an engine stall caused by a sudden increase in the traction load.

As one of the means for making the present invention more suitable,
A roller that can rotate around an axis parallel to the swing axis of the swing member is provided at a receiving portion of the swing member in the receiving member.

According to this means, in the second conversion state of the change amount conversion mechanism, when the swing member slides with respect to the receiving member due to the relative swing between the load detection member and the swing member, the sliding is accompanied by the sliding. The roller rotates in the sliding direction.
As a result, the swing member slides smoothly with respect to the receiving member, and the load detection member and the swing member smoothly swing relative to each other.
As a result, the draft control in the second conversion state of the change amount conversion mechanism can be smoothly performed.

As one of the means for making the present invention more suitable,
The holding mechanism includes a stopper that restricts the swinging member from swinging in a direction that lowers the three-point link mechanism with respect to the load detecting member, and swinging the swinging member toward the stopper. It is equipped with a spring to force.

According to this means, the load detecting member and the swinging member can be integrally swung when the change amount conversion mechanism is in the first conversion state with a simple configuration provided with a stopper and a spring, and the amount of change can be changed. When the conversion mechanism is in the second conversion state, the load detection member and the swing member can swing relative to each other.
As a result, it is possible to preferably switch between the first conversion state and the second conversion state of the change amount conversion mechanism while simplifying the configuration.

As one of the means for making the present invention more suitable,
The operating tool is arranged adjacent to the driver's seat at a position behind the driver's seat in the vehicle body.

According to this means, the operator can operate the operating tool by reaching toward the rear part of the driver's seat while sitting in the driver's seat, and the conversion state of the change amount conversion mechanism can be easily performed. Can be switched to.

As one of the means for making the present invention more suitable,
The change amount conversion mechanism is arranged adjacent to the driver's seat at a position behind the driver's seat in the vehicle body.

According to this means, the operator can easily confirm the operating state of the change amount conversion mechanism by visually observing the rear portion of the driver's seat while sitting in the driver's seat.
Further, since the rear portion of the driver's seat is not covered with a cover or the like above the driver's seat, maintenance of the change amount conversion mechanism can be easily performed.

FIG. 5 is a right side view of a tractor in which a plow is attached to a three-point link mechanism in the first embodiment. FIG. 5 is a right side view of a tractor in which a rotary tillage device is attached to a three-point link mechanism in the first embodiment. It is a vertical sectional right side view of the main part which shows the structure of the elevating drive unit and the mechanical linkage unit in 1st Embodiment. It is a top view of the main part which shows the structure of the elevating drive unit and the mechanical linkage unit in 1st Embodiment. It is an exploded perspective view of the main part which shows the structure of the elevating drive unit and the mechanical linkage unit in 1st Embodiment. It is a vertical development right side view of the main part which shows the operating state of the elevating drive unit when the tilling device is stopped elevating by holding the position of the height setting lever on the low setting side. It is a vertical development right side view of the main part which shows the operating state of the elevating drive unit when the tilling device is raised in conjunction with the swinging operation of a height setting lever in a high setting direction. It is a vertical development right side view of the main part which shows the operating state of the elevating drive unit when the tilling device is stopped elevating by holding the position of the height setting lever on the high setting side. It is an exploded perspective view of the main part which shows the structure of the change amount conversion mechanism and the like in 1st Embodiment. It is a rear view of the main part which shows the structure of the change amount conversion mechanism and the like in 1st Embodiment. It is sectional drawing of XI-XI in FIG. It is a longitudinal right side view of the main part which shows the operating state of the mechanical linking unit and the elevating drive unit when the traction load does not exceed the set value in the 1st conversion state of the change amount conversion mechanism in 1st Embodiment. It is a longitudinal right side view of the main part which shows the operating state of the mechanical linking unit and the elevating drive unit when the traction load exceeds the set value in the 1st conversion state of the change amount conversion mechanism in 1st Embodiment. It is a longitudinal right side view of the main part which shows the operating state of the mechanical linking unit and the elevating drive unit when the traction load does not exceed the set value in the 2nd conversion state of the change amount conversion mechanism in 1st Embodiment. It is a vertical sectional right side view of the main part which shows the operating state of the mechanical linking unit and the elevating drive unit when the traction load exceeds the set value in the 2nd conversion state of the change amount conversion mechanism in 1st Embodiment. It is a longitudinal right side view of the main part which shows the operating state of the mechanical linkage unit and the elevating drive unit when the tillage depth reaches the set tillage depth in the second linkage conversion state of the change amount conversion mechanism in 1st Embodiment. .. It is a longitudinal right side view of the main part which shows the operating state of the mechanical linkage unit and the elevating drive unit when the tillage depth is deeper than the set tillage depth in the second linkage conversion state of the change amount conversion mechanism in the first embodiment. .. FIG. 2 is a right side view of a tractor in which a plow is attached to a three-point link mechanism in the second embodiment. It is a vertical sectional right side view of the main part which shows the structure of the elevating drive unit and the mechanical linkage unit in 2nd Embodiment. It is a vertical sectional right side view of the main part which shows the operating state of the mechanical coupling unit and the elevating drive unit when the traction load does not exceed the set value in 2nd Embodiment. It is a vertical sectional right side view of the main part which shows the operating state of the mechanical coupling unit and the elevating drive unit when the traction load exceeds a set value in 2nd Embodiment.

[First Embodiment]
Hereinafter, the first embodiment, which is an example of the embodiment for carrying out the present invention, will be described with reference to the drawings.
The direction indicated by the arrow of reference numeral F shown in FIG. 1 is the front side of the tractor, and the direction indicated by the arrow of reference numeral U is the upper side of the tractor.

As shown in FIGS. 1 and 2, the tractors illustrated in the first embodiment include a front frame 1 arranged at the front of the vehicle body, an engine 2 connected to the rear of the front frame 1, and a rear end of the engine 2. The clutch housing 3 connected to the lower part, the intermediate frame 4 connected to the rear end of the clutch housing 3, and the transmission case also used as the rear frame connected to the rear end of the intermediate frame 4 (hereinafter referred to as T / M case). ) 5, left and right front wheels 6 arranged on the left and right of the front frame 1, left and right rear wheels 7 arranged on the left and right of the T / M case 5, left and right rear fenders 8 covering the left and right rear wheels 7, and the vehicle body. It is equipped with a boarding-type driver 9 located at the rear, and the like.

Although not shown, the power from the engine 2 is mainly built in the T / M case 5 via the main clutch built in the clutch housing 3 and the transmission shaft covered with the intermediate frame 4. It is transmitted to the transmission. Then, the power after shifting by the main transmission is transmitted to the left and right front wheels 6 and the left and right rear wheels 7 via the auxiliary transmission and the like built in the T / M case 5.

As shown in FIGS. 1 and 2, the driving unit 9 includes a steering wheel 10 for steering the front wheels, a driver's seat 11 arranged between the left and right rear fenders 8, and the like.

A three-point link mechanism 12 that enables attachment of a working device is connected to the rear portion of the T / M case 5 so as to swing up and down. The three-point link mechanism 12 includes a single top link 13, left and right lower links 14, and the like. Thereby, when the tilling work is performed by this tractor, the towed tilling device 15 which is an example of the working device can be attached to the three-point link mechanism 12.

In the first embodiment, the plow 15A, which is an example of the traction type tilling device 15, is attached to the three-point link mechanism 12 (see FIG. 1), and the rotary, which is an example of the traction type tilling device 15. The state in which the tilling device 15B is attached to the three-point link mechanism 12 (see FIG. 2) is illustrated, but the three-point link mechanism 12 is of a traction type such as a disc halo, a cultivator, and a subsoiler. The tilling device 15 can be attached.

As shown in FIGS. 1 to 8, the tractor includes a mechanically linked hydraulic lifting device 16. The hydraulic elevating device 16 selectively elevates and elevates either the hydraulic elevating drive unit 17 that elevates and drives the tilling device 15 together with the three-point link mechanism 12, and the amount of change in the traction load and the amount of change in the plowing depth. It is provided with a mechanical linkage unit 18 for automatic elevating and lowering, which is converted into an operation amount and transmitted to the elevating and lowering drive unit 17.

The elevating drive unit 17 includes left and right lift arms 20 that suspend and support the left and right lower links 14 via left and right support members 19, hydraulic cylinders 21 that swing and drive the left and right lift arms 20 in the vertical direction, and hydraulic cylinders 21. Control valve 22 for controlling the operation of the cultivating device 15, height setting lever 23 for setting the control target height of the tilling device 15, friction type holding mechanism 24 for holding the height setting lever 23 at an arbitrary operating position, and control valve 22. A first link mechanism 25 for interlocking the spool 22A with the height setting lever 23, a feedback link mechanism 26 for interlocking the spool 22A with the left and right lift arms 20, and the like are provided. The control valve 22 is provided internally with an urging means (not shown) for returning the spool 22A to a descending position on the front side of the vehicle body.

The first link mechanism 25 can swing back and forth to the first swing arm 27 and the spool 22A of the control valve 22 that come into contact with the height setting lever 23 from the rear side of the vehicle body (the high setting side of the height setting lever 23). A balance arm 28 supported by the above, a first crankshaft 29 extending from the swing center of the first swing arm 27 to the upper end of the balance arm 28, and the like are provided. When the height setting lever 23 is swung in the high setting direction (rear direction of the vehicle body), the first link mechanism 25 uses the spool 22A of the control valve 22 as an urging means in conjunction with the operation. Move from the neutral position to the ascending position against it. In the first link mechanism 25, when the height setting lever 23 is swung in the low setting direction (front direction of the vehicle body), the spool 22A of the control valve 22 is neutralized by the action of the urging means in conjunction with the operation. Allows movement from position to descending position.

The feedback link mechanism 26 includes a linking rod 30 extending from the right lift arm 20 to the front side of the vehicle body, a second swing arm 31 interlocking with the left and right lift arms 20 via the linking rod 30, and a second swing arm. A second crankshaft 32 extending from the swing center of 31 to the lower end of the balance arm 28 is provided. When the tilling device 15 reaches the control target height, the feedback link mechanism 26 moves the spool 22A of the control valve 22 from the ascending position or the descending position to the neutral position in conjunction with the arrival.

According to the above configuration, when the operator operates the height setting lever 23 to raise the control target height of the tilling device 15, the first link mechanism 25 causes the spool 22A of the control valve 22 to be operated. Move from the neutral position to the ascending position (see FIG. 7). As a result, the tilling device 15 rises together with the left and right lift arms 20. Then, when the tilling device 15 reaches the control target height by this ascent, the feedback link mechanism 26 moves the spool 22A of the control valve 22 from the ascending position to the neutral position in conjunction with this (see FIG. 8). As a result, the tilling device 15 stops ascending together with the left and right lift arms 20.
Further, when the operator operates the height setting lever 23 to lower the control target height of the tilling device 15, the first link mechanism 25 moves from the neutral position of the spool 22A to the descending position in accordance with this operation. The movement is allowed, and the spool 22A moves from the neutral position to the descending position by the action of the urging means. As a result, the tilling device 15 is lowered together with the left and right lift arms 20. Then, when the tilling device 15 reaches the control target height by this lowering, the feedback link mechanism 26 moves the spool 22A of the control valve 22 from the lowering position to the neutral position in conjunction with this. As a result, the tilling device 15 stops descending together with the left and right lift arms 20.

That is, in this tractor, by providing the above-mentioned elevating drive unit 17, the position control for elevating and displacement the tilling device 15 to an arbitrary control target height set by the operation of the height setting lever 23 is satisfactorily performed. Can be done. Then, by this position control, the plowing depth at the time of plowing work can be set to an arbitrary depth.

As shown in FIGS. 1 to 5 and 9 to 17, the mechanical linkage unit 18 has a change amount conversion mechanism 33 and a change amount conversion mechanism 33 that can switch between the first linkage conversion state and the second linkage conversion state. It is provided with a second link mechanism 34 for interlocking and connecting the elevating drive unit 17 and an operating tool 35 for switching the change amount conversion mechanism 33 between the first linkage conversion state and the second linkage conversion state. The change amount conversion mechanism 33 includes a load detecting member 36 that swings back and forth according to a traction load transmitted via the top link 13, and a grounding body 37 that detects the plowing depth of the tilling device 15 (FIGS. 2, 16 to 17). It has a swinging member 38, etc. that swings according to the plowing depth of the tilling device 15 by being interlocked with (see).

Of the various tillage devices 15 that can be connected to the three-point link mechanism 12, the plow 15A (see FIG. 1), the subsoiler, and the like do not have the grounding body 37. The rotary tiller 15B (see FIG. 2) is provided with a rear cover that functions as a grounding body 37 so as to be able to swing up and down. Therefore, in the state where the plow 15A is attached to the three-point link mechanism 12, the mechanical linking unit 18 is in the draft control state (first linking state) in which the interlocking connection between the swing member 38 and the grounding body 37 is released. (See FIGS. 1, 3-5, 9-15). Further, in the state where the rotary tillage device 15B is attached to the three-point link mechanism 12, the mechanical linking unit 18 is an automatic tillage in which the swing member 38 and the grounding body 37 are interlocked and connected via the third link mechanism 39. The deep control state (second linkage state) is set (see FIGS. 2 and 16 to 17).

In the draft control state of the mechanical linkage unit 18, when the change amount conversion mechanism 33 is switched to the first linkage conversion state described above, the change amount conversion mechanism 33 is traction load obtained by swinging the load detection member 36 back and forth. It becomes possible to convert the amount of change in the above into an elevating operation amount (see FIGS. 1, 3 to 5, and 9 to 15).
In the automatic tillage depth control state of the mechanical linkage unit 18, when the change amount conversion mechanism 33 is switched to the second linkage conversion state described above, the change amount conversion mechanism 33 is cultivated obtained by swinging the swing member 38. It becomes possible to convert the amount of change in depth into the amount of lifting operation (see FIGS. 2 and 16 to 17).
As a result, when the plow 15A is used for tilling work in this tractor, the mechanical linkage unit 18 is brought into the draft control state (first linkage state) by attaching the plow 15A to the three-point link mechanism 12. Then, in this draft control state, when the operator operates the operating tool 35 to switch the change amount conversion mechanism 33 to the conversion state for the first linkage, the plow 15A is subjected to the traction load during the tilling work. Draft control is performed to automatically move up and down. As a result, engine stall due to an increase in traction load can be avoided.
Further, when the rotary tillage device 15B is used for tilling work in this tractor, the rotary tillage device 15B is attached to the three-point link mechanism 12, and the swing member 38 and the ground contact body 37 are connected to each other via the third link mechanism 39. By interlocking and connecting, the mechanical linkage unit 18 is in the automatic tillage depth control state (second linkage state). Then, in this automatic tillage depth control state, when the operator operates the operating tool 35 to switch the change amount conversion mechanism 33 to the second linkage conversion state, the tillage depth is adjusted during the tillage work. Automatic tillage depth control is performed in which the rotary tillage device 15B automatically moves up and down in conjunction with the vertical swing of the ground contact body (rear cover) 37. As a result, highly accurate tillage work can be performed while the tillage depth is kept constant.
That is, in this tractor, by providing the mechanical linking unit 18 having the above-described configuration, the above-mentioned draft control can be performed when the plow 15A is used for tilling work. Further, when the tilling work is performed by the rotary tilling device 15B, the above-mentioned automatic tilling depth control can be performed.

As shown in FIGS. 3 to 5, 9 to 10 and 12 to 17, the swing member 38 is swingably supported by the load detection member 36. The operating tool 35 has a contact position that contacts the load detection member 36 to prevent the load detection member 36 from swinging back and forth, and a non-contact position that allows the load detection member 36 to swing back and forth without contacting the load detection member 36. It includes a contact member 40 that moves over a position. Then, when the contact member 40 is in the non-contact position, the load detection member 36 swings back and forth, so that the amount of change in the traction load is transmitted to the elevating drive unit 17 as the elevating operation amount. Further, when the contact member 40 is in the contact position, the swing member 38 swings independently while the load detection member 36 does not swing back and forth, so that the amount of change in plowing depth is transmitted to the lift drive unit 17 as the lift operation amount. ..
That is, when the contact member 40 is in the non-contact position, the change amount conversion mechanism 33 is in the above-mentioned first linkage conversion state, and when the contact member 40 is in the contact position, the change amount conversion mechanism 33 is in the above-mentioned second state. It will be in the conversion state for linkage.
As a result, in the automatic tillage depth control during the tillage work by the rotary tillage device 15B, the load detection member 36 does not swing back and forth according to the traction load transmitted via the top link 13, and thus the load detection member 36 does not swing back and forth. There is no possibility that the amount of change in the traction load is input to the amount of change conversion mechanism 33 due to the back-and-forth swing of.
As a result, in the automatic tillage depth control based on the change amount of the tillage depth, it is possible to avoid the possibility that the work accuracy is lowered due to the change amount of the traction load being input to the change amount conversion mechanism 33.

As shown in FIGS. 2 and 16 to 17, the ground contact body 37 of the rotary tillage device 15B is spring-loaded in the downward direction (ground contact direction). The third link mechanism 39 provides a reversing arm 41 supported by the rotary tillage device 15B, a linking rod 42 extending between the grounding body 37 and the reversing arm 41, a control cable 43 extending between the reversing arm 41 and the swing member 38, and the like. I have. Then, one end of the control cable 43 is detachably pin-connected to a portion of the swing member 38 above the swing fulcrum.

A plurality of connecting holes 38A for control cables are formed on the upper side of the swing member 38. Thereby, the connection position of the control cable 43 with respect to the swing member 38 can be changed, and by this change, the swing displacement amount of the swing member 38 with respect to the swing displacement amount of the ground body 37 can be changed. As a result, in the automatic tillage depth control, it is possible to adjust the responsiveness when the rotary tillage device 15B moves up and down in conjunction with the vertical swing of the ground contact body 37 according to the tillage depth.
In this first embodiment, two connecting holes 38A are formed in the swinging member 38 as a plurality of connecting holes 38A, but three or more connecting holes 38A are formed in the swinging member 38. It may be formed in.

As shown in FIGS. 1, 3 to 5, and 10 to 15, in the three-point link mechanism 12 to which the plow 15A is attached, the front end portion of the top link 13 is connected to the load detecting member 36 via the first connecting pin 44. It is connected. Further, the front ends of the left and right lower links 14 are connected to the left and right brackets 45 provided at the rear ends of the T / M case 5 via the left and right second connecting pins 46. Due to this connecting structure, the traction load during the tilling work acts on the load detecting member 36 via the top link 13.

As shown in FIGS. 3 to 5 and 9 to 17, the load detection member 36 swings in the front-rear direction via the first support shaft 48 to the support member 47 fixed to the rear end of the T / M case 5. It is supported so that it can be displaced. The mechanical linking unit 18 swings the load detection member 36 in a direction (rear direction of the vehicle body) that opposes the traction load applied to the load detection member 36, and a urging mechanism 49, and the load detection member 36 swings back and forth. A limiting mechanism 50, which limits the range, is provided. The load detecting member 36 is held in a reference posture extending vertically upward from the first support shaft 48 by the action of the urging mechanism 49 and the limiting mechanism 50. Then, when the traction load exceeds the set value, the load detection member 36 swings and displaces from the reference posture to the front side of the vehicle body against the action of the urging mechanism 49 in conjunction with the increase in the traction load. In conjunction with the decrease in the traction load, the urging mechanism 49 swings and displaces to the rear side of the vehicle body to return to the reference posture. The free end portion of the load detection member 36 is provided with a second support shaft 51 that supports the swing member 38 so as to be swingable.

As shown in FIGS. 3 to 10 and 12 to 17, the change amount conversion mechanism 33 includes a holding mechanism 52 that urges the swing member 38 to return to a predetermined posture with respect to the load detecting member 36. When the swing member 38 is interlocked and connected to the ground body 37, the swing member 38 is set to be connected so that the predetermined posture of the swing member 38 corresponds to the lowest descending position of the ground body 37. In the swing member 38, the above-mentioned second link mechanism 34 is pin-connected to a portion below the swing fulcrum of the swing member 38. The second link mechanism 34 includes an operation arm 53 that is supported by a linking portion 27A of the first swing arm 27 so as to be swingable back and forth, a reversing arm 54 that reverses the operation direction, and one end of the operation arm 53 and the reversing arm 54. It includes a first linking member 55 that spans, and a second linking member 56 that spans the other end of the reversing arm 54 and the swing member 38. The linking portion 27A of the first swing arm 27 is formed in a U shape in a plan view. By swinging the operation arm 53 in the rear direction of the vehicle body (the high setting direction of the height setting lever 23), the linking portion 27A of the first swing arm 27 from the front side of the vehicle body (the low setting side of the height setting lever 23). Contact.
With this configuration, when the change amount conversion mechanism 33 is switched to the first linkage conversion state in the draft control state of the mechanical linkage unit 18, when the traction load increases, the holding mechanism 52 is held in conjunction with this increase. By the action, the load detection member 36 and the swing member 38 swing integrally toward the front side of the vehicle body. Further, when the traction load decreases, the load detection member 36 and the swing member 38 swing integrally toward the rear side of the vehicle body due to the holding action of the holding mechanism 52 in conjunction with this reduction.
When the load detection member 36 and the swing member 38 swing integrally toward the front side of the vehicle body, the operation arm 53 swings in the rear direction of the vehicle body in conjunction with the integral swing, and the swing causes the operation arm 53 to swing. The linking portion 27A of the first swing arm 27 is pressed in the rearward direction of the vehicle body. As a result, the first swing arm 27 swings in the rearward direction of the vehicle body, and the spool 22A of the control valve 22 linked to the first swing arm 27 rises from the neutral position against the action of the urging means. (See FIG. 13). As a result, the plow 15A rises along with the left and right lift arms 20.
Further, when the load detection member 36 and the swing member 38 swing integrally toward the rear side of the vehicle body, the operation arm 53 swings in the front direction of the vehicle body in conjunction with the integral swing, and the swing causes the operation arm 53. Is separated from the linking portion 27A of the first swing arm 27 in the front direction of the vehicle body. As a result, the first swing arm 27 is allowed to swing in the front direction of the vehicle body, and the spool 22A of the control valve 22 moves from the neutral position to the descending position by the action of the urging means. As a result, the plow 15A descends together with the left and right lift arms 20.
On the other hand, when the change amount conversion mechanism 33 is switched to the second linkage conversion state in the automatic tillage depth control state of the mechanical linkage unit 18, when the tillage depth becomes deeper and the ground contact body 37 rises, it is linked to this rise. The rocking member 38 swings independently with respect to the load detecting member 36 in the backward tilting direction against the urging of the holding mechanism 52. Further, when the plowing depth becomes shallow and the ground contact body 37 descends, the rocking member 38 swings independently with respect to the load detecting member 36 in the forward tilting direction due to the urging of the holding mechanism 52 in conjunction with this lowering. To do.
Then, when the swing member 38 swings independently in the backward tilting direction, the operation arm 53 swings in the rearward direction of the vehicle body in conjunction with the independent swing, and the operation arm 53 swings in the first swing arm by this swing. The linking portion 27A of 27 is pressed toward the rear of the vehicle body. As a result, the first swing arm 27 swings in the rearward direction of the vehicle body, and the spool 22A of the control valve 22 linked to the first swing arm 27 rises from the neutral position against the action of the urging means. (See FIG. 17). As a result, the rotary tiller 15B rises together with the left and right lift arms 20.
Further, when the swing member 38 swings independently in the forward tilting direction, the operation arm 53 swings in the forward direction of the vehicle body in conjunction with the independent swing, and the operation arm 53 swings in the first swing arm by this swing. It separates from the linking portion 27A of 27 in the front direction of the vehicle body. As a result, the first swing arm 27 is allowed to swing in the front direction of the vehicle body, and the spool 22A of the control valve 22 moves from the neutral position to the descending position by the action of the urging means. As a result, the rotary tiller 15B is lowered together with the left and right lift arms 20.

In the draft control state of the mechanical linking unit 18 described above, the feedback link mechanism 26 stops the integral swing of the load detection member 36 and the swing member 38 according to the traction load due to the rise or fall of the plow 15A. The spool 22A of the control valve 22 is moved from the ascending position or the descending position to the neutral position in conjunction with the swing stop. As a result, the plow 15A stops ascending or descending together with the left and right lift arms 20.
The feedback link mechanism 26 swings when the independent swing of the swing member 38 according to the tilling depth is stopped by raising or lowering the rotary tilling device 15B in the automatic tilling depth control state of the mechanical linking unit 18 described above. In conjunction with the stop, the spool 22A of the control valve 22 is moved from the ascending position or the descending position to the neutral position. As a result, the rotary tiller 15B stops ascending or descending together with the left and right lift arms 20.

With the above configuration, the tractor is provided with the mechanical linkage unit 18 having the above-described configuration, so that the above-mentioned draft control can be satisfactorily performed when the plow 15A is used for tilling work. Further, when the tilling work is performed by the rotary tilling device 15B, the above-mentioned automatic tilling depth control can be satisfactorily performed.

As shown in FIGS. 3 to 5, 9 to 10 and 12 to 17, the holding mechanism 52 swings in the direction in which the swing member 38 lowers the three-point link mechanism 12 with respect to the load detection member 36. It is provided with a stopper 57 for limiting the movement and a spring 58 for swinging and urging the swing member 38 toward the stopper 57.
That is, with a simple configuration including the stopper 57 and the spring 58, when the change amount conversion mechanism 33 is in the conversion state for the first linkage, the load detection member 36 and the swing member 38 can be integrally rocked. When the change amount conversion mechanism 33 is in the second linkage conversion state, the swing member 38 can swing independently with respect to the load detection member 36.
As a result, it is possible to preferably switch between the first linkage conversion state and the second linkage conversion state of the change amount conversion mechanism 33 while simplifying the configuration.

The stopper 57 is supported by the load detection member 36. The spring 58 is erected over the load detecting member 36 and the second linking member 56.

As shown in FIGS. 3 to 5, 9 to 10 and 12 to 15, the change amount conversion mechanism 33 has a first conversion state (see FIGS. 12 to 13) and a second conversion state (see FIGS. 12 to 13) as the first linkage conversion state. (See FIGS. 14 to 15). The change amount conversion mechanism 33 is switched between the first conversion state and the second conversion state by the operation of the operation tool 35 described above.
When the change amount conversion mechanism 33 is in the first conversion state, the load detection member 36 and the swing member 38 swing integrally due to the holding action of the holding mechanism 52, and the integrally swing causes the load detection member 36 to move back and forth. The amount of change in the traction load obtained by rocking is not amplified and is transmitted to the elevating drive unit 17 as an elevating operation amount (see FIGS. 12 to 13).
Further, when the change amount conversion mechanism 33 is in the second conversion state, the relative swing between the load detection member 36 and the swing member 38 that opposes the holding action of the holding mechanism 52 is allowed, and the load is detected by this relative swing. The amount of change in the traction load obtained by swinging the member 36 back and forth is amplified and transmitted to the elevating drive unit 17 as the elevating operation amount (see FIGS. 14 to 15).
As a result, for example, when the plow 15A is used for tilling work in a standard field where the traction load is unlikely to increase due to the hardness of the soil and the traction load is unlikely to fluctuate sharply, the operator operates the operating tool 35. When the change amount conversion mechanism 33 is switched to the first conversion state, the plow 15A can be moved up and down according to the traction load at a standard speed suitable for this field. As a result, it is possible to avoid engine stall due to an increase in traction load while performing draft control in which the change in plowing depth is gentle.
Further, for example, when the plow 15A is used for tilling work in a field where the traction load is likely to be large due to the hardness of the soil and the traction load is liable to fluctuate, the operator operates the operating tool 35 to change the amount of change. By switching the conversion mechanism 33 to the second conversion state, the plow 15A can be raised and lowered according to the traction load at a high speed suitable for this field. As a result, it is possible to avoid an engine stall caused by a sudden increase in the traction load.

As shown in FIGS. 3 to 5, 9 to 10 and 12 to 17, the operating tool 35 includes a receiving member 59 that moves between the non-receiving position and the receiving position. Then, when the receiving member 59 is located at the non-receiving position, the receiving member 59 is removed from the swinging region of the swinging member 38, and the load detecting member 36 and the swinging member 38 are subjected to the holding action of the holding mechanism 52. Swings integrally. Further, when the receiving member 59 is located at the receiving position, the holding mechanism is held while the receiving member 59 is located in the swing region of the rocking member 38 and the rocking member 38 is not received by the receiving member 59. The load detection member 36 and the swing member 38 swing integrally due to the holding action of 52, and while the swing member 38 is received by the receiving member 59, the load detection resists the holding action of the holding mechanism 52. Relative swing between the member 36 and the swing member 38 is allowed.
That is, in addition to the holding mechanism 52 described above, the operating tool 35 is only provided with the receiving member 59, and when the receiving member 59 is in the non-receiving position, the load detecting member 36 and the swinging member 38 are integrated. The first conversion state of the swinging change amount conversion mechanism 33 can be obtained. Further, when the receiving member 59 is in the receiving position, it is possible to obtain a second conversion state of the change amount conversion mechanism 33 in which the relative swing between the load detecting member 36 and the swing member 38 is allowed.
As a result, it is possible to satisfactorily switch between the first conversion state and the second conversion state of the change amount conversion mechanism 33 while simplifying the configuration.

In the second conversion state of the change amount conversion mechanism 33, when the load detection member 36 is in the reference posture, a gap is secured between the swing member 38 and the receiving member 59. Therefore, the receiving member 59 is the swinging member until the swinging displacement amount of the load detecting member 36 based on the traction load from the reference posture reaches a predetermined amount in which the swinging member 38 comes into contact with the receiving member 59. By not receiving the 38, the load detection member 36 and the swing member 38 swing integrally. When the amount of swing displacement of the load detection member 36 from the reference posture becomes a predetermined amount or more, the receiving member 59 receives the swing member 38, so that the load detection member 36 and the swing member 38 swing relative to each other. ..
As a result, in a work situation where the traction load slightly exceeds the set value and there is no risk of causing an engine stall, the plow 15A has a traction load at a standard speed even when the change amount conversion mechanism 33 is in the second conversion state. It is driven up and down according to.
As a result, it is possible to avoid a possibility that the durability of the elevating drive unit 17 is lowered due to the plow 15A being moved up and down at an unnecessarily high speed even in a work situation where the traction load slightly exceeds the set value. Can be done.

When the relative swing between the load detection member 36 and the swing member 38 is allowed in the second conversion state of the change amount conversion mechanism 33, when the traction load rises, the load detection member 36 moves in conjunction with this rise. While swinging toward the front side of the vehicle body, the swinging member 38 swings relative to the rearward tilting direction against the urging of the holding mechanism 52. Further, when the traction load decreases, the load detection member 36 swings toward the rear side of the vehicle body in conjunction with this reduction, and the swing member 38 swings relative to the forward tilt direction due to the urging of the holding mechanism 52. ..
When the load detection member 36 swings toward the front of the vehicle body and the swing member 38 swings relative to the rearward tilt direction, the operation arm 53 swings in the rearward direction of the vehicle body in conjunction with the relative swing. Upon swinging, the operating arm 53 presses the linking portion 27A of the first swinging arm 27 in the rearward direction of the vehicle body. As a result, the first swing arm 27 swings in the rearward direction of the vehicle body, and the spool 22A of the control valve 22 linked to the first swing arm 27 rises from the neutral position against the action of the urging means. (See FIG. 15). As a result, the plow 15A rises along with the left and right lift arms 20.
Further, when the load detection member 36 swings to the rear side of the vehicle body and the swing member 38 swings relative to the forward tilt direction, the operation arm 53 swings to the front of the vehicle body in conjunction with this relative swing. Due to this swing, the operation arm 53 is separated from the linking portion 27A of the first swing arm 27 in the front direction of the vehicle body. As a result, the first swing arm 27 is allowed to swing in the front direction of the vehicle body, and the spool 22A of the control valve 22 moves from the neutral position to the descending position by the action of the urging means. As a result, the plow 15A descends together with the left and right lift arms 20.

When the feedback link mechanism 26 stops the relative swing between the load detecting member 36 and the swing member 38 according to the traction load due to the rise or fall of the plow 15A in the second conversion state of the change amount conversion mechanism 33 described above, In conjunction with this swing stop, the spool 22A of the control valve 22 is operated from the ascending position or the descending position to the neutral position. As a result, the plow 15A stops ascending or descending together with the left and right lift arms 20.

With the above configuration, in this tractor, by providing the mechanical linkage unit 18 having the above-described configuration, it is possible to select draft control in consideration of the hardness of soil and the like, which are different for each field. As a result, the tilling work with the plow 15A can be satisfactorily performed regardless of the hardness of the soil which differs depending on the field.

The receiving portion of the swinging member 38 in the receiving member 59 is provided with a roller 60 that can rotate around the axis parallel to the swinging axis of the swinging member 38.
With this configuration, when the swing member 38 slides with respect to the receiving member 59 due to the relative swing between the load detection member 36 and the swing member 38 in the second conversion state of the change amount conversion mechanism 33, the swing member 38 is not affected. The roller 60 rotates in the sliding direction as it slides.
As a result, the swing member 38 slides smoothly with respect to the receiving member 59, and the load detection member 36 and the swing member 38 smoothly swing relative to each other.
As a result, the draft control of the change amount conversion mechanism 33 in the second conversion state can be smoothly performed.

As shown in FIGS. 1 and 2, the change amount conversion mechanism 33 is arranged adjacent to the driver's seat 11 at a position behind the driver's seat 11 in the vehicle body. As a result, the operator can easily confirm the operating state of the change amount conversion mechanism 33 by visually observing the rear portion of the driver's seat 11 while sitting on the driver's seat 11.
Further, since the rear portion of the driver's seat 11 is not covered with a cover or the like above the driver's seat 11, maintenance of the change amount conversion mechanism 33 can be easily performed.

The operating tool 35 is arranged adjacent to the driver's seat 11 at a position behind the driver's seat 11 in the vehicle body. As a result, the operator can operate the operating tool 35 by reaching for the rear portion of the driver's seat 11 while sitting on the driver's seat 11, and the change amount conversion mechanism 33 is first. It is possible to easily switch between the conversion state, the second conversion state, and the conversion state for the second linkage.

As shown in FIGS. 3 to 5, 9 to 10, and 12 to 17, the operating tool 35 includes a rocking plate 61 and a rocking plate that are swingably supported in the left-right direction by the support member 47 described above. An operation handle 62, which extends forward from 61, is provided. A plate-shaped contact member 40 is provided on the left side portion of the rocking plate 61, and a receiving member 59 is provided on the right side portion of the rocking plate 61. The operating tool 35 swings in the left-right direction around the axis X extending in the front-rear direction. The operating tool 35 is selectively held at one of the first operating position, the second operating position, and the third operating position by the detent mechanism 63 provided over the support member 47 and the rocking plate 61. ..
When the position of the operating tool 35 is held at the first operating position on the right side, the contact member 40 is located at the non-contact position and the receiving member 59 is located at the non-receiving position. As a result, the change amount conversion mechanism 33 is in the first conversion state for draft control.
When the operating tool 35 is held at the second operating position in the middle of the left and right, the contact member 40 is located at the non-contact position, and the receiving member 59 is located at the receiving position. As a result, the change amount conversion mechanism 33 is in the second conversion state for draft control.
When the position of the operating tool 35 is held at the third operating position on the left side, the contact member 40 is located at the contact position and the receiving member 59 is located at the non-receiving position. As a result, the change amount conversion mechanism 33 is in the second linkage conversion state for automatic plowing depth control.
That is, the operator switches the operation position of the operating tool 35 to change the amount of change conversion mechanism 33 into a first conversion state for draft control, a second conversion state for draft control, and automatic tillage control. It can be easily switched to the conversion state for the second linkage.

As shown in FIGS. 3, 5, and 9 to 17, the load detecting member 36 includes left and right side wall portions 36A having facing through holes 36a. The support member 47 includes a vertical wall portion 47A connected to the rear portion of the vehicle body, and a plan-view U-shaped linking portion 47B extending rearward from the vertical wall portion 47A and entering between the left and right side wall portions 36A. ing. In the linking portion 47B, left and right elongated holes 47a long in the front-rear direction are formed at positions facing the through holes 36a of each side wall portion 36A. The limiting mechanism 50 described above is provided by the through holes 36a of the load detection member 36, the elongated holes 47a of the support member 47, and the linking pins 64 inserted into the through holes 36a and the elongated holes 47a. It is configured.
That is, the front-rear swing range of the load detection member 36 is limited by the front-rear length of each elongated hole 47a formed in the support member 47.

The limiting mechanism 50 includes a rubber block 65 that is fitted into the space between the vertical wall portion 47A and the linking portion 47B of the support member 47. The rubber block 65 is formed with an elongated hole 65a having a shorter front-rear length than the elongated hole 47a of the support member 47 at a position facing the elongated hole 47a of the support member 47. Then, the linking pin 64 is inserted into the elongated hole 65a.
As a result, when the limiting mechanism 50 limits the back-and-forth swing of the load detecting member 36, the linking pin 64 of the limiting mechanism 50 collides with the rubber block 65, so that the linking pin 64 collides with the linking portion 47B of the support member 47. It is possible to prevent the generation of noise due to a collision.

As shown in FIGS. 3 to 6 and 12 to 17, the mechanical linkage unit 18 includes a sensitivity adjusting mechanism 66 that adjusts the operating sensitivity when the elevating drive unit 17 is interlocked with the swing member 38. The sensitivity adjusting mechanism 66 is a sensitivity adjusting lever 67 arranged so as to be able to hold a position in an arbitrary operation position in the driving unit 9, a linking member 69 extending from the sensitivity adjusting lever 67 to a support shaft 68 of the reversing arm 54, and a reversing arm 54. A support member 70 that supports the support shaft 68 so as to be displaceable in the front-rear direction is provided. When the support position of the support shaft 68 by the support member 70 is changed in the front-rear direction by the swing operation of the sensitivity adjustment lever 67 in the front-rear direction, the sensitivity adjustment mechanism 66 causes the first swing in conjunction with this change. The gap 71 between the linking portion 27A of the arm 27 and the operating arm 53 is changed. Thereby, the operating sensitivity when the elevating drive unit 17 is interlocked with the swing member 38 can be adjusted.

The sensitivity adjusting mechanism 66 becomes more sensitive to the operating sensitivity when the elevating drive unit 17 is interlocked with the swing member 38 as the above-mentioned gap 71 becomes smaller, and when the traction load exceeds the set value and the plow 15A rises. The responsiveness is improved.
In the sensitivity adjusting mechanism 66, as the gap 71 described above becomes larger, the operating sensitivity when the elevating drive unit 17 is interlocked with the swing member 38 becomes insensitive, and when the traction load exceeds the set value and the plow 15A rises. Poor responsiveness.
As a result, the plow 15A frequently moves up and down to hunt by desensitizing the above-mentioned operating sensitivity as the change in the traction load becomes more severe due to the field conditions such as the undulations of the field. It is possible to prevent a decrease in tillage work accuracy due to this.

As shown in FIGS. 1 to 3, 5, 9, and 11 to 17, the load detecting member 36 has a long top link 13A (see FIGS. 1, 3, 5, 9, and 11 to 15). It includes a first connecting portion 36B to be connected and a second connecting portion 36C to which a bracket 72 (see FIGS. 2 and 16 to 17) supporting a short top link 13B is connected.
As a result, for example, when performing tillage work with the rotary tillage device 15B, the specifications of the three-point link mechanism 12 are the standard link specification including the long top link 13A and the left and right lower links 14, and the short top link 13B and the left and right. It can be easily changed to a special link specification having a lower link 14.
When the specifications of the three-point link mechanism 12 are changed from the standard link specifications to the special link specifications, the lifting drive amount of the rotary tillage device 15B with respect to the lifting operation amount of the lifting drive unit 17 becomes larger, and the maximum of the rotary tilling device 15B. The ascending position becomes higher.
As a result, for example, when the rotary tillage device 15B is used for tilling work in a work area having high ridges, the specifications of the three-point link mechanism 12 are changed from the standard link specifications to the special link specifications to overcome the ridges. It becomes easy to avoid the possibility that the rotary tiller 15B comes into contact with the high ridges when traveling or turning at the ridges.

The load detecting member 36 is provided with a single connecting hole as the first connecting portion 36B, which enables pin connection of the long top link 13A. Further, the load detection member 36 is provided with two upper and lower connecting holes as the second connecting portion 36C, which enable pin connection of the bracket 72.

[Second Embodiment]
Hereinafter, a second embodiment, which is an example of the embodiment for carrying out the present invention, will be described with reference to the drawings.
The tractor illustrated in the second embodiment is different from the tractor illustrated in the first embodiment except in the configuration of the mechanical linking unit 18 for automatic elevating and lowering, and the other configurations are the same. Only the configuration of the mechanical linking unit 18 for automatic elevating and lowering will be described.
Also in this second embodiment, the direction indicated by the arrow of reference numeral F shown in FIG. 18 is the front side of the tractor, and the direction indicated by the arrow of reference numeral U is the upper side of the tractor.

As shown in FIGS. 18 to 21, in the mechanical linking unit 18 for automatic ascending / descending illustrated in the second embodiment, a traction type tilling device 15 such as a plow 15A or a subsoiler (not shown) has a three-point link mechanism 12 It is configured to convert the amount of change in the traction load into the amount of elevating operation and transmit it to the hydraulic elevating drive unit 17 during the tilling work attached to the above.
That is, the mechanical linking unit 18 for automatic raising and lowering is configured for draft control that enables only draft control that automatically raises and lowers the tilling device 15 according to the traction load during the tilling work.

The mechanical linkage unit 18 moves up and down with a change amount conversion mechanism 33 having a load detection member 36 that swings back and forth according to a traction load transmitted via the top link 13 of the three-point link mechanism 12, and a change amount conversion mechanism 33. It is provided with a second link mechanism 34 that interlocks and connects with the drive unit 17. The configuration of the second link mechanism 34 is the same as the configuration exemplified in the first embodiment.

The change amount conversion mechanism 33 has a swing member 38 that is swingably supported by the load detection member 36 and is interlocked and connected to the elevating drive unit 17 via the second link mechanism 34, and the load detection member 36. The amount of change in the traction load obtained by the back-and-forth swing is amplified by the relative swing between the load detection member 36 and the swing member 38, and then converted into an elevating operation amount.

With this configuration, for example, when the traction load changes in the cultivating work in which the plow 15A is attached to the three-point link mechanism 12 as the traction type tilling device 15, the load detecting member corresponds to the amount of change in the traction load at this time. In addition to the 36 swinging back and forth, the amount of change in the traction load is amplified by the relative swinging of the load detecting member 36 and the swinging member 38. Then, the amount of change in the traction load after amplification is converted into an elevating operation amount and transmitted to the elevating drive unit 17.
As a result, the plow 15A can be quickly moved up and down in response to a change in the traction load, and as a result, even when the traction load suddenly increases, engine stall due to the increase in the traction load can be avoided.

Further, since the load detection member 36 and the swing member 38 swing relative to each other, the amount of change in the traction load can be greatly amplified while narrowing the swing range of the load detection member 36 and the swing member 38. As a result, the front-rear length of the space required for installing the change amount conversion mechanism 33 having the load detection member 36 and the swing member 38 can be shortened.
As a result, it is possible to avoid an engine stall caused by a sudden increase in the traction load while suppressing an increase in the size of the vehicle body, which increases the overall length of the vehicle body.

As shown in FIGS. 19 to 21, the load detection member 36 is supported by a support member 47 fixed to the rear end of the T / M case 5 via a first support shaft 48 so as to be swing-displaceable in the front-rear direction. ing. The free end portion of the load detection member 36 is provided with a second support shaft 51 that supports the swing member 38 so as to swing back and forth. In the swing member 38, the above-mentioned second link mechanism 34 is pin-connected to a portion below the swing fulcrum (second support shaft 51) of the swing member 38.

The mechanical linking unit 18 swings the load detection member 36 in a direction (rear direction of the vehicle body) that opposes the traction load applied to the load detection member 36, and a urging mechanism 49, and the load detection member 36 swings back and forth. A limiting mechanism 50, which limits the range, is provided. The configuration of the urging mechanism 49 and the limiting mechanism 50 is the same as the configuration illustrated in the first embodiment.

The load detecting member 36 is held in a reference posture extending vertically upward from the first support shaft 48 by the action of the urging mechanism 49 and the limiting mechanism 50. Then, when the traction load exceeds the set value, the load detection member 36 swings and displaces from the reference posture to the front side of the vehicle body against the action of the urging mechanism 49 in conjunction with the increase in the traction load. In conjunction with the decrease in the traction load, the urging mechanism 49 swings and displaces to the rear side of the vehicle body to return to the reference posture.

The change amount conversion mechanism 33 has a holding mechanism 52 that urges the swing member 38 to return to a predetermined posture with respect to the load detection member 36. The holding mechanism 52 swings the swing member 38 toward the stopper 57 and the stopper 57 that restricts the swing member 38 from swinging in the direction in which the three-point link mechanism 12 is lowered with respect to the load detection member 36. It is equipped with a mobilizing spring 58. The stopper 57 is supported by the load detection member 36. The spring 58 is erected over the load detecting member 36 and the second linking member 56 of the second link mechanism 34.

The change amount conversion mechanism 33 has a receiving member 59 arranged in the swing region of the swing member 38 so that the upper side of the swing member 38 can be received from the front side of the vehicle body. The receiving member 59 is supported by the upper end portion of the supporting member 47.

The change amount conversion mechanism 33 is configured to secure a gap between the swing member 38 and the receiving member 59 when the load detecting member 36 is in the reference posture.
Therefore, the receiving member 59 is the swinging member until the swinging displacement amount of the load detecting member 36 based on the traction load from the reference posture reaches a predetermined amount in which the swinging member 38 comes into contact with the receiving member 59. By not receiving the 38, the load detection member 36 and the swing member 38 swing integrally due to the holding action of the holding mechanism 52. As a result, the amount of change in the traction load obtained by swinging the load detection member 36 back and forth is not amplified and is transmitted to the elevating drive unit 17 as an elevating operation amount.
Then, when the amount of oscillating displacement of the load detecting member 36 from the reference posture becomes a predetermined amount or more, the receiving member 59 receives the oscillating member 38, so that the load detecting member 36 resists the holding action of the holding mechanism 52. Relative swing with the swing member 38 is allowed. As a result, the amount of change in the traction load obtained by the forward / backward swing of the load detection member 36 is amplified by the relative swing between the load detection member 36 and the swing member 38, and then transmitted to the lift drive unit 17 as the lift operation amount. Be done.
That is, in a work situation where the traction load slightly exceeds the set value and there is no possibility of causing an engine stall, the elevating drive unit 17 responds to the traction load of the plow 15A at a standard speed suitable for the work situation at this time. To drive up and down.
Further, in a work situation where the traction load greatly exceeds the set value and there is a high possibility that the engine stalls, the elevating drive unit 17 raises and lowers the plow 15A according to the traction load at a high speed suitable for the work situation at this time. Drive.
As a result, even in a work situation where the traction load slightly exceeds the set value, the durability of the elevating drive unit 17 is increased due to the elevating drive unit 17 driving the plow 15A up and down at an unnecessarily high speed. It is possible to avoid an engine stall caused by a sudden increase in the traction load while avoiding the possibility of a decrease.

As shown in FIGS. 18 to 21, when the traction load increases when the relative swing between the load detecting member 36 and the swing member 38 is allowed, the change amount conversion mechanism 33 interlocks with the rise and loads the load. The detection member 36 swings toward the front side of the vehicle body, and the swing member 38 swings relative to the rearward tilting direction against the urging of the holding mechanism 52. Further, when the traction load decreases, the load detection member 36 swings toward the rear side of the vehicle body in conjunction with this reduction, and the swing member 38 swings relative to the forward tilt direction due to the urging of the holding mechanism 52. ..
When the load detection member 36 swings toward the front of the vehicle body and the swing member 38 swings relative to the rearward tilt direction, the operation arm 53 swings in the rearward direction of the vehicle body in conjunction with the relative swing. Upon swinging, the operating arm 53 presses the linking portion 27A of the first swinging arm 27 in the rearward direction of the vehicle body. As a result, the first swing arm 27 swings in the rearward direction of the vehicle body, and the spool 22A of the control valve 22 linked to the first swing arm 27 rises from the neutral position against the action of the urging means. Move to. As a result, the plow 15A rises along with the left and right lift arms 20.
Further, when the load detection member 36 swings to the rear side of the vehicle body and the swing member 38 swings relative to the forward tilt direction, the operation arm 53 swings to the front of the vehicle body in conjunction with this relative swing. Due to this swing, the operation arm 53 is separated from the linking portion 27A of the first swing arm 27 in the front direction of the vehicle body. As a result, the first swing arm 27 is allowed to swing in the front direction of the vehicle body, and the spool 22A of the control valve 22 moves from the neutral position to the descending position by the action of the urging means. As a result, the plow 15A descends together with the left and right lift arms 20.
Then, when the relative swing between the load detecting member 36 and the swing member 38 corresponding to the traction load is stopped by the ascending or descending of the plow 15A, the feedback link mechanism 26 of the lifting drive unit 17 is interlocked with the swing stop. Operates the spool 22A of the control valve 22 from the ascending position or the descending position to the neutral position. As a result, the plow 15A stops ascending or descending together with the left and right lift arms 20.

As shown in FIGS. 19 to 21, a roller 60 that can rotate around an axial center parallel to the oscillating axis of the oscillating member 38 is provided at a receiving portion of the oscillating member 38 in the receiving member 59. ..
With this configuration, in the change amount conversion mechanism 33, when the swing member 38 slides with respect to the receiving member 59 due to the relative swing between the load detection member 36 and the swing member 38, the sliding is accompanied by the sliding. The roller 60 rotates in the sliding direction.
As a result, the swing member 38 slides smoothly with respect to the receiving member 59, and the load detection member 36 and the swing member 38 smoothly swing relative to each other, so that draft control can be smoothly performed. it can.

As shown in FIG. 18, the change amount conversion mechanism 33 is arranged adjacent to the driver's seat 11 at a position behind the driver's seat 11 in the vehicle body. As a result, the operator can easily confirm the operating state of the change amount conversion mechanism 33 by visually observing the rear portion of the driver's seat 11 while sitting on the driver's seat 11.
Further, since the rear portion of the driver's seat 11 is not covered with a cover or the like above the driver's seat 11, maintenance of the change amount conversion mechanism 33 can be easily performed.

As shown in FIGS. 20 to 21, the mechanical linkage unit 18 includes a sensitivity adjusting mechanism 66 that adjusts the operating sensitivity when the elevating drive unit 17 is interlocked with the swing member 38. The sensitivity adjusting mechanism 66 has the same configuration as that illustrated in the first embodiment, and as a result, the more the change in the traction load becomes more severe due to the field conditions such as the undulations of the field, the more the operation described above is performed. By desensitizing the sensitivity, it is possible to prevent a decrease in tillage work accuracy due to the plow 15A frequently moving up and down and hunting.

[Another Embodiment]
The present invention is not limited to the configurations exemplified in the above-mentioned first embodiment and the second embodiment, and the following, typical alternative embodiments relating to the present invention will be exemplified.

[1] The configuration of the tractor can be changed in various ways.
For example, the tractor may be configured as a semi-crawler specification in which left and right crawlers are provided instead of the left and right rear wheels 7.
For example, the tractor may be configured to have a full crawler specification in which left and right crawlers are provided instead of the left and right front wheels 6 and the left and right rear wheels 7.
For example, the tractor may be configured to have an electric specification including an electric motor instead of the engine 2.
For example, the tractor may be configured in a hybrid specification including an engine 2 and an electric motor.

[2] The working device attached to the three-point link mechanism 12 may be a mower or a seeder other than the tilling device.
Then, during work running in which a mower or a seeder is attached to the three-point link mechanism 12, the operator positions the operating tool 35 at the third operating position and converts the change amount conversion mechanism 33 for the second linkage. By switching to the state, it is possible to prevent the load detecting member 36 from swinging back and forth according to the traction load, and it is possible to avoid the possibility that the mower or the seeder moves up and down due to the traction load during the work.

[3] The configuration of the elevating drive unit 17 can be changed in various ways.
For example, the elevating drive unit 17 may be configured to include a hydraulic motor or the like instead of the hydraulic cylinder 21.
For example, the elevating drive unit 17 may be configured to include an urging means for returning the spool 22A of the control valve 22 to the descending position on the outside of the control valve 22.

[4] The mechanical linkage unit 18 is, for example, as a swing member 38, swingably supported by a swing member 38 for draft control supported by a load detection member 36 and swingably supported by a support member 47. A swing member 38 for automatic tillage control is provided, and as a link mechanism 34, a link mechanism 34 for draft control that interlocks and connects the swing member 38 for draft control to the elevating drive unit 17 and automatic tillage are provided. It is equipped with a link mechanism 34 for automatic tillage control that interlocks and connects the swing member 38 for depth control to the elevating drive unit 17, and the load detection member 36 and the swing member 38 for draft control are operated by operating the operating tool 35. The first conversion state that allows the integral swing with and prevents the swing member 38 for automatic tillage control, and the relative swing between the load detection member 36 and the swing member 38 for draft control. The second conversion state that allows and prevents the swinging member 38 for automatic tillage control, and the load detecting member 36 and the swinging member 38 for draft control are prevented from swinging and for automatic tillage control. The configuration may be such that the swing member 38 is switched to the second linkage conversion state that allows the swing of the swing member 38.

[5] The configuration of the change amount conversion mechanism 33 can be changed in various ways.
For example, the change amount conversion mechanism 33 may have a configuration in which the first conversion state and the second conversion state are provided without the second linkage conversion state.
For example, the change amount conversion mechanism 33 has a first conversion state in which the load detection member 36 is connected to the link mechanism 34 and a second conversion state in which the swing member 38 is connected to the link mechanism 34 by operating the operating tool 35. It may be configured to switch to and.

[6] The configuration of the load detection member 36 can be changed in various ways.
For example, the load detection member 36 may have a configuration in which the upper end portion thereof is supported by the support member 47 via the first support shaft 48.
For example, the load detection member 36 may be supported by the support member 47 so as to be swingable back and forth via a first support shaft 48 that is long in the vertical direction.

[7] The holding mechanism 52 swings the swing member 38 in a predetermined posture, the spring receiving member fixed at a position facing each other in the axial direction of the second support shaft 51, and the swing member 38 in a predetermined posture. It may be composed of a torsion spring for urging. In this configuration, the torsion spring is assembled in a state where the coil portion of the torsion spring is fitted onto the second support shaft 51 and both ends of the torsion spring sandwich the spring receiving member and the swing member 38 in a predetermined posture. Be done.

The present invention comprises a hydraulic lifting drive unit that lifts and lowers a tow-type tillage device attached to a three-point link mechanism together with the three-point link mechanism, and the lifting and lowering drive by converting the amount of change in the traction load into a lifting operation amount. It can be applied to a tractor equipped with a mechanical linkage unit for automatic lifting to convey to the unit.

11 Driver's seat 12 3-point link mechanism 13 Top link 15 Tillage device 17 Lifting drive unit 18 Mechanical linkage unit 33 Change amount conversion mechanism 34 Link mechanism 35 Operation tool 36 Load detection member 38 Swing member 52 Holding mechanism 57 Stopper 58 Spring 59 Receiving member 60 roller

Claims (9)

A three-point link mechanism that is vertically swingably connected to the rear part of the vehicle body, a hydraulic elevating drive unit that elevates and lowers a tow-type tillage device attached to the three-point link mechanism together with the three-point link mechanism, and towing. It is equipped with a mechanical linkage unit for automatic lifting that converts the amount of change in load into the amount of lifting operation and transmits it to the lifting drive unit.
The mechanical linkage unit includes a change amount conversion mechanism having a load detection member that swings back and forth according to a traction load transmitted via the top link of the three-point link mechanism, the change amount conversion mechanism, and the elevating drive unit. Equipped with a link mechanism that interlocks and connects
The change amount conversion mechanism has a swing member that is swingably supported by the load detection member and is interlocked and connected to the lift drive unit via the link mechanism, and swings back and forth of the load detection member. The load detection member uses the first conversion state in which the change amount of the traction load obtained by motion is converted into the elevating operation amount without amplifying the movement, and the change amount of the traction load obtained by the back-and-forth swing of the load detection member. The tractor is configured to be switchable to a second conversion state in which the tractor is amplified by the relative swing between the swing member and the swing member and then converted into the lifting operation amount. When pre-Symbol change amount conversion mechanism of the first conversion condition, the by integral oscillation of the load detection member and the swing member, the lifting drive as the lifting operation amount without being amplified variation of the traction load Informed to the unit
When the change amount conversion mechanism is in the second conversion state, the change amount of the traction load is amplified by the relative swing between the load detection member and the swing member, and the lift operation amount is used as the lift operation amount in the lift drive unit. The tractor according to claim 1 to be communicated. The tractor according to claim 1 or 2, wherein the mechanical linking unit includes an operation tool for switching the change amount conversion mechanism between the first conversion state and the second conversion state. The change amount conversion mechanism includes a holding mechanism that urges the swing member to a predetermined posture with respect to the load detection member.
The operating tool includes a receiving member that moves between a non-receiving position and a receiving position.
When the receiving member is located at the non-receiving position, the receiving member deviates from the rocking region of the rocking member and does not receive the rocking member, so that the load detecting member and the rocking member Will swing integrally due to the holding action of the holding mechanism.
When the receiving member is located at the receiving position, the receiving member is located within the rocking region of the rocking member to receive the rocking member, whereby the load detecting member and the rocking member The tractor according to claim 3, wherein the relative swinging against the holding action of the holding mechanism is allowed. When the receiving member is located at the receiving position, the load detecting member and the swinging member are integrally shaken by the holding action of the holding mechanism while the swinging member is not received by the receiving member. A claim that allows relative swinging between the load detecting member and the swinging member against the holding action of the holding mechanism while the swinging member is moving and being received by the receiving member. Item 4. The tractor according to item 4. The tractor according to claim 4 or 5, wherein a roller that can rotate around an axis parallel to the swing axis of the swing member is provided at a receiving portion of the swing member in the receiving member. The holding mechanism includes a stopper that restricts the swinging member from swinging in a direction that lowers the three-point link mechanism with respect to the load detecting member, and swinging the swinging member toward the stopper. The tractor according to any one of claims 4 to 6, further comprising a spring to force. The tractor according to any one of claims 3 to 7, wherein the operating tool is arranged adjacent to the driver's seat at a position behind the driver's seat in the vehicle body. The tractor according to any one of claims 1 to 8, wherein the change amount conversion mechanism is arranged adjacent to the driver's seat at a position behind the driver's seat in the vehicle body.

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