JP6151949B2 - Work machine coupling device - Google Patents

Description

  The present invention relates to a work machine connection device that connects a vehicle and a work machine.

  A flooded soil filled with water such as paddy fields has a soft mud layer on the surface side and a hard cultivating layer below the mud layer. A working machine that performs sowing work on this flooded soil is known (see, for example, Patent Documents 1 to 3). The working machine for sowing makes a ditch in the soil while being pulled by the vehicle, sows in the ditch, and covers the ditch.

  For example, the direct sowing machines described in Patent Documents 1 and 2 include a soil covering plate for covering the groove, a sensor for detecting the soil softness in the vehicle 10, and an inclination angle of the soil covering plate with respect to the soil according to the soil softness. And a control unit for adjusting.

  Moreover, the direct seeding machine described in Patent Literature 1 further includes a hydraulic cylinder that can be expanded and contracted in accordance with control of the control unit, and a lift link device that converts expansion and contraction of the hydraulic cylinder into a lift operation of the work implement. This direct sowing machine adjusts the depth of the grooving by raising and lowering the working machine by controlling the expansion and contraction of the hydraulic cylinder according to the hardness of the soil.

JP 2010-51211 A JP 2004-201579 A JP-A-8-37808

  With the recent increase in the speed of work vehicles and work machines, work machines become more susceptible to soil irregularities, and it is desired to improve the ability of the work machines to follow the soil surface. In the direct seeding machine described in Patent Document 1, when the work machine is tilted, the work machine can be moved up and down to follow the soil surface, but when the work machine is tilted, the grooving and covering soil are incomplete. there is a possibility. That is, the groove and soil covering may become incomplete during expansion and contraction of the hydraulic cylinder.

  This invention is made | formed in view of such a condition, The objective is to provide the working machine connection apparatus which improved the followable | trackability to the soil of a working machine.

  In order to solve the above-described problem, a work machine connection device according to an aspect of the present invention is a work machine connection device that connects a work machine that works on soil to a vehicle body, and connects the vehicle body and the work machine, A link mechanism that can be expanded and contracted between work machines, and an expansion and contraction mechanism for expanding and contracting the link mechanism are provided. The link mechanism presses the work machine against the soil or lifts the work machine by the extension / contraction of the extension / contraction mechanism, and the extension / contraction mechanism absorbs the load transmitted from the vehicle body and the work machine to the link mechanism and performs the extension / contraction operation of the extension / contraction mechanism. It has a load absorption part to convert.

  According to this aspect, the external force from the vehicle body or the work machine is absorbed by the load absorbing portion and converted into an expansion / contraction operation, and the link mechanism is expanded / contracted. Thereby, it can suppress transmitting the shaking of a vehicle body to a working machine. Further, the swing of the work implement can be absorbed by the expansion and contraction of the load absorbing portion and the link mechanism. Thereby, the followable | trackability to the soil of a working machine can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, in the working machine connection apparatus which connects a working machine with a vehicle, the followable | trackability to the soil of a working machine can be improved.

It is a figure for demonstrating the vehicle to which the working machine and the working machine connection device were attached. It is a figure for demonstrating a float. It is a schematic diagram for demonstrating an expansion-contraction mechanism. It is a figure which shows the function of a control part. It is a figure for demonstrating the working machine coupling device of a comparison technique. It is a figure for demonstrating the effect | action of a link mechanism. It is a flowchart which shows the load control process of a working machine. It is a figure for demonstrating the working machine coupling device of a modification.

  Flooded soil such as paddy fields has two layers, a soft mud layer on the surface side and a hard cultivating layer below the mud layer. The work vehicle, for example, attaches a direct sowing machine to the rear part and moves the cultivating layer of flooded soil while pulling the direct sowing machine. The direct sowing machine is supported by a float and floats in a mud layer, and it is desirable to sow seeds in the mud layer at a certain depth. There is a height difference in the plow layer where the work vehicle moves, and when the direct sowing machine moves up and down due to the height difference, the position of the seed also moves up and down. Therefore, a control device for controlling the float to follow the surface of the mud layer is provided. In recent years, since the work speed in a work vehicle has been increased, higher tracking performance is desired.

  FIG. 1 is a diagram for explaining a vehicle 10 to which a work implement 12 and a work implement coupling device 18 are attached. The vehicle 10 is, for example, an agricultural tractor or a civil engineering work vehicle. A work machine 12 for working on soil is attached to the rear side of the vehicle 10. As the vehicle 10 advances, the work implement 12 is dragged to the soil. The work machine connection device 18 connects the work machine 12 to the vehicle body 10a. The vehicle body 10a is supported by wheels.

  The work machine 12 has a float 14 and a direct sowing machine 16 and has a total weight of about 200 kilograms including seeds, for example. The float 14 is a floating boat that floats in a muddy layer if there is no direct sowing machine 16. The direct sowing machine 16 holds seeds and seeds them according to the vehicle speed of the vehicle 10. The seed held by the direct seeder 16 is about 60 kilograms at maximum, and the weight is reduced by sowing.

  In addition, the working machine 12 is not limited to the direct seeding machine 16, and may have another apparatus. For example, it may be a rice transplanter for planting rice seedlings in paddy fields, a grooving machine for making grooves in paddy fields, or a paddy weeding machine for removing paddy field weeds. In any case, the work implement 12 is controlled by the work implement coupling device 18 so as to follow the surface of the soil.

  The float 14 is coupled to the expansion / contraction adjustment mechanism 28 by a shaft support portion 32 located on the upper surface. On the lower surface of the float 14, a groove forming portion 20 and a soil covering portion 22 are provided. The groove forming part 20 forms a groove in the mud layer, and the soil covering part 22 covers the groove formed by the groove forming part 20 with soil. The direct sowing machine 16 sown seeds between the grooving part 20 and the covering soil part 22.

  The work machine coupling device 18 controls the load of the work machine 12 so that the work machine 12 follows the mud layer. The work machine coupling device 18 includes a hardness / softness detection sensor 24, a control unit 26, an expansion / contraction adjustment mechanism 28, an inclination angle sensor 30, and a spring length sensor (not shown).

  The control unit 26 is connected to the hardness / softness detection sensor 24, the inclination angle sensor 30, and the expansion / contraction adjustment mechanism 28 by wire or wirelessly. The control unit 26 processes the detection result of each sensor and controls the expansion / contraction adjustment mechanism 28. The control unit 26 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, a backup RAM that can retain stored contents even when the engine is stopped, and the like. It comprises an A / D converter for converting analog signals input from a nonvolatile memory, an input / output interface, various sensors, etc. into digital signals, and a timer for timing.

  The softness detection sensor 24 detects the softness of the soil mud layer based on the penetration depth of the tip of the soil, and transmits the detection result to the control unit 26. A high hardness indicates that the soil is hard, and a low hardness indicates that the soil is soft. The softness detection sensor 24 is attached to the front side of the float 14 and detects the softness of the soil at a position in front of the float 14 and behind the vehicle body 10a. The tilt angle sensor 30 detects the tilt angle of the link mechanism of the expansion / contraction adjustment mechanism 28 and transmits the detection result to the control unit 26. The expansion / contraction adjustment mechanism 28 receives a control signal from the control unit 26 and expands / contracts according to the control signal to adjust a load for lifting the work implement 12. The control unit 26 starts control when the driver turns on a control start switch (not shown), and stops control when turned off.

  FIG. 2 is a diagram for explaining the float 14. FIG. 2A is a top view of the float 14, and FIG. 2B is a side view of the float 14. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  A soil covering portion 22 is provided behind the groove forming portion 20 in the traveling direction. The soil covering portion 22 is a plate material provided so as to be inclined in the traveling direction, and is provided at a position overlapping the groove forming portion 20 in the traveling direction. A notch portion 21 is provided between the groove forming portion 20 and the soil covering portion 22. The direct sowing machine 16 sows seeds in the space formed by the cutout portion 21 and the soil covering portion 22 covers the soil. When the float 14 is greatly inclined, the covering of the covering portion 22 is incomplete. Further, if the mud layer is hard, the float 14 floats and the soil covering becomes incomplete.

  The float 14 is rotatably connected to the expansion / contraction adjustment mechanism 28 by a shaft support portion 32. The shaft support 32 is provided behind the center or center of gravity of the float 14 in the traveling direction. That is, the shaft support portion 32 is provided at an eccentric position. Thereby, the inclination of the float 14 can be corrected with a small force by changing the load applied to the shaft support portion 32.

  FIG. 3 is a schematic diagram for explaining the expansion / contraction adjustment mechanism 28. FIG. 3A is a side view of the expansion / contraction adjustment mechanism 28, and FIG. 3B is a top view of a part of the expansion / contraction adjustment mechanism 28. 3A is simplified, and FIG. 3B is a diagram for illustrating the connection of the hydraulic cylinder 36 and the link mechanism 34 in detail, showing the spring connection portion 40 in detail. . The expansion / contraction adjustment mechanism 28 includes a link mechanism 34, a hydraulic cylinder 36, a spring coupling portion 40, and a spring member 42. The hydraulic cylinder 36, the spring connecting portion 40, and the spring member 42 function as an expansion / contraction mechanism that expands / contracts the link mechanism 34.

  The link mechanism 34 connects the vehicle body 10a and the work machine 12, and can extend and contract between the work machine 12 and the vehicle body 10a. The vehicle side link 34 a of the link mechanism 34 is connected to the vehicle body 10 a, and the work machine side link 34 b is connected to the shaft support portion 32 of the float 14. The vehicle side link 34a may be a part of the vehicle body 10a. The first connection link 34c and the second connection link of the link mechanism 34 connect the vehicle side link 34a and the work implement side link 34b. In the link mechanism 34, each link is rotatably connected by a first shaft portion 44, a second shaft portion 46, a third shaft portion 48, and a fourth shaft portion 50 (referred to as “shaft portion” if they are not distinguished from each other). The The tilt angle sensor 30 detects the tilt angle of the link mechanism 34 with respect to the vehicle body.

  The hydraulic cylinder 36 has one end connected to the vehicle body 10 a and the other end connected to the first shaft portion 44 of the link mechanism 34 via the spring member 42. The hydraulic cylinder 36 allows the rod 38 to enter and exit from the cylinder under the control of the control unit 26, and expands and contracts its entire length. The expansion and contraction of the link mechanism 34 means that the interval from the first shaft portion 44 to the fourth shaft portion 50 changes.

  As shown in FIG. 3B, one end of the spring member 42 is connected to the end portion of the rod 38, and the other end is connected to the first shaft portion 44 of the link mechanism 34 via the spring connecting portion 40. . The spring member 42 is a coil spring and indirectly connects the rod 38 and the link mechanism 34. The spring connecting portion 40 is formed in a “U” shape and is rotatably connected to the first shaft portion 44. The spring connecting portion 40 transmits the urging force received from the spring member 42 to the first shaft portion 44.

  The spring length sensor 52 detects the length of the spring member 42 and transmits the detection result to the control unit 26. Depending on the length of the spring member 42, the load that the hydraulic cylinder 36 applies to the work implement 12 via the link mechanism 34 is obtained.

  The link mechanism 34 performs an operation of pressing the work machine against the soil and an operation of lifting the work machine by the expansion and contraction of the hydraulic cylinder 36. That is, since the link mechanism 34 and the hydraulic cylinder 36 extend and contract from the vehicle body 10a on the ground toward the soil, the link mechanism 34 and the hydraulic cylinder 36 can be lifted and pressed up and down against the float 14. When the link mechanism 34 and the hydraulic cylinder 36 are extended, the float 14 is pressed downward, and when it is contracted, the float 14 is lifted upward.

  FIG. 4 is a diagram illustrating functions of the control unit 26. The control unit 26 includes a hardness / softness acquisition unit 60, an inclination angle acquisition unit 62, a load acquisition unit 64, a target load derivation unit 66, a weight estimation unit 67, and an expansion / contraction control unit 68. The hardness / softness acquisition unit 60 receives the detection result of the hardness / softness detection sensor 24 and acquires the hardness of the soil.

  The inclination angle acquisition unit 62 receives the detection result of the inclination angle sensor 30, and acquires the inclination angle of the link mechanism 34 with respect to the vehicle body 10a. In the case of flat soil, the vehicle-side link 34a is substantially vertical, so the inclination angle is an inclination angle with respect to the vertical direction.

  The load acquisition unit 64 receives the detection result of the spring length sensor 52 and acquires the spring length of the spring member 42. Since the spring length of the spring member 42 is proportional to the lifting load of the work machine 12 by the hydraulic cylinder 36, the load acquisition unit 64 acquires the lifting load from the spring length.

  The target load deriving unit 66 derives a target load to be applied to the work machine 12 according to the hardness of the soil. Specifically, the softness of the soil is received from the softness acquisition unit 60, a first target load that the work implement 12 should give to the soil is derived, and a second target load that lifts the work implement 12 vertically upward is obtained. To derive.

  The target load deriving unit 66 reduces the load for lifting the work implement 12 if the soil is relatively hard, and increases the load for lifting the work implement 12 if the soil is relatively soft. To derive. That is, the target load deriving unit 66 derives the first target load so as to increase the load of the work machine 12 on the soil as the soil becomes harder. As a result, the working machine 12 can be pressed against the soil sufficiently to cover the ditch and cover the hard soil, and the float 14 can be prevented from floating due to the reaction force from the hard soil. Moreover, the working machine 12 can be pressed too much against soft soil, and excessive grooves can be suppressed.

  The target load deriving unit 66 subtracts the first target load that the work implement 12 should give to the soil from the weight of the work implement when deriving the second target load that lifts the work implement 12 vertically. The weight of the work machine 12 increases or decreases by about 60 kilograms according to the increase or decrease of seeds. The weight estimation unit 67 estimates the weight of the work implement 12 based on the inclination angle of the link mechanism 34 and the spring length of the spring member 42 when the work implement 12 is lifted from the soil. The spring length of the spring member 42 corresponds to a load for lifting the work implement 12 by the hydraulic cylinder 36. When the work machine 12 is lifted from the soil, the work machine 12 is lifted from the soil when the vehicle 10 turns in the paddy field and turns to the next stroke. The weight estimation unit 67 can derive the target load in accordance with the increase or decrease of the weight of the work machine 12 due to sowing.

  The target load deriving unit 66 receives the inclination angle of the link mechanism 34 from the inclination angle acquisition unit 62, corrects the second target load according to the inclination angle of the link mechanism 34, and generates a third pressure in the hydraulic cylinder 36. Deriving the target load. The target load deriving unit 66 sends the third target load to the expansion / contraction control unit 68. The target load deriving unit 66 derives each target load using a predetermined calculation formula or a two-dimensional map indicating the relationship between the detection result of each sensor and the target load.

  The expansion / contraction control unit 68 derives a target spring length at which the biasing force of the spring member 42 becomes the third target load. The expansion / contraction control unit 68 controls the total length of the hydraulic cylinder 36 so that the spring member 42 has a target spring length. That is, the expansion / contraction control unit 68 expands / contracts the entire length of the hydraulic cylinder 36 according to the target load. The hydraulic cylinder 36 is an inexpensive one that only expands and contracts in response to an instruction signal from the expansion and contraction control unit 68 and does not have a function of adjusting the load. By using the spring member 42, the load exerted by the hydraulic cylinder 36 can be adjusted at a low cost.

  FIG. 5 is a diagram for explaining the working machine coupling device 70 of the comparative technique. The work machine 12 is connected to the vehicle 10 by a work machine connection device 70 that is a link. In the comparative technique, no means for controlling the load of the work machine 12 such as the work machine connecting device 18 is provided.

  The flooded soil is composed of a hard tiller layer 72 and a soft mud layer 74. The vehicle 10 moves on the cultivating layer 72, and the float 14 moves while floating on the mud layer 74. The cultivating layer 72 has a portion that is not flat, and when the front wheel of the vehicle 10 enters the recess 72a, a swing is generated in which the rear wheel side relatively rises. The working machine 12 rises in conjunction with this shaking, and the float 14 may be separated from the soil.

  FIG. 6 is a diagram for explaining the operation of the link mechanism 34. The schematic diagram which expanded the working machine coupling device 18 is shown on the lower side of this figure. As shown to Fig.6 (a), if the soil is flat, the float 14 will not float from soil.

  As shown in FIG. 6B, when the front wheel falls into the recess, the rear wheel relatively rises and the vehicle side link 34a also rises. At this time, the hydraulic cylinder 36 is also pulled up by the vehicle side link 34a. Although there is no change in the total length of the hydraulic cylinder 36, the spring member 42 pulled from the hydraulic cylinder 36 contracts and the link mechanism 34 extends. That is, the hydraulic cylinder 36 protrudes from the spring connecting portion 40 by the length of the spring member 42 contracted, and the total length of the hydraulic cylinder 36 and the spring connecting portion 40 is increased. Thereby, the link mechanism 34 extends and the height of the work machine side link 34b from the soil does not change. The vertical movement of the vehicle side link 34 a is absorbed by the spring member 42, converted into the expansion / contraction operation of the link mechanism 34, and is not easily transmitted to the work machine 12.

  Further, when the depth of the mud layer 74 changes, an external force is input from the work machine 12 to the link mechanism 34. For example, when the depth of the mud layer 74 suddenly becomes shallow, the link mechanism 34 is pulled by the work machine 12. At this time, since the spring member 42 is contracted and the link mechanism 34 is extended, the lifting / lowering operation of the work machine 12 with respect to the vehicle body 10a is absorbed.

  The spring member 42 functions as a load absorbing portion that absorbs a load transmitted from the vehicle side link 34a or the work machine side link 34b to the link mechanism 34 and converts it into an expansion / contraction operation. The link mechanism 34 is also expanded and contracted by the expansion and contraction operation of the spring member 42. The spring member 42 indirectly connects the hydraulic cylinder 36 to the link mechanism 34 and is interposed in the expansion and contraction of the link mechanism 34 and the hydraulic cylinder 36. The spring member 42 can absorb the shaking of the vehicle 10 and suppress the float 14 from moving up and down.

  The softness / softness detection sensor 24 is attached in front of the float 14, that is, in front of the groove forming part 20 and the soil covering part 22. Since the control unit 26 performs control based on the detection result of the hardness detection sensor 24, the control delay can be suppressed by detecting the state of the soil before the groove forming unit 20 and the soil covering unit 22 operate.

  FIG. 7 is a flowchart showing the load control process of the work machine 12. The driver lowers the work machine 12 to the soil at the start position, starts control by the control unit 26, and advances the vehicle 10. The target load deriving unit 66 acquires the soil softness from the softness acquiring unit 60 (S10).

  The target load deriving unit 66 calculates a first target load that should be applied to the soil by the work machine 12 according to the hardness (S12). The target load deriving unit 66 subtracts the first target load from the estimated weight of the work implement 12 to calculate a second target load that lifts the work implement 12 vertically upward (S14).

  The target load deriving unit 66 acquires the inclination angle of the link mechanism 34 from the inclination angle acquisition unit 62 (S16). The target load deriving unit 66 corrects the second target load according to the inclination angle and calculates the third target load (S18). While the second target load is a load that works vertically upward, the link mechanism 34 and the hydraulic cylinder 36 are inclined from the vehicle body 10a toward the soil, and therefore the second target load is inclined at the inclination angle of the link mechanism 34. Convert the target load.

  The target load deriving unit 66 controls the spring length of the spring member 42 according to the third target load (S20). The target load deriving unit 66 controls the expansion and contraction of the hydraulic cylinder 36 so that the load applied to the spring member 42 becomes the third target load, and lifts the work machine 12 with the second target load. 12 causes the first target load to be applied to the soil. Thus, the load of the work machine 12 on the soil is controlled.

  FIG. 8 is a view for explaining a working machine coupling device 118 of a modified example. Although the configuration of the link mechanism 34 is omitted in FIG. 8, the work machine connection device 118 has the same link mechanism 34 as the work machine connection device 18. In the work machine coupling device 18 shown in FIG. 3, the load is controlled using the spring member 42, whereas in the modified work machine coupling device 118, the load is controlled by controlling the hydraulic pressure of the hydraulic cylinder 136. To do.

  The work machine connection device 118 includes a link mechanism 34, a pressure gauge 102, an accumulator 104, a valve 110, a pump 112, a hydraulic cylinder 136, a rod 138, and a connection part 140.

  One end of the connecting portion 140 is rotatably connected to the first shaft portion 44 of the link mechanism 34, and the other end is directly connected to the rod 138 of the hydraulic cylinder 136. The hydraulic cylinder 136 has one end connected to the vehicle side link 34 a of the vehicle body 10 a and the other end connected to the first shaft portion 44 via the connecting portion 140. The point that the link mechanism 34 expands and contracts according to the expansion and contraction of the hydraulic cylinder 136 is the same as that of the work machine coupling device 18 of the embodiment. The hydraulic cylinder 136 and the connecting portion 140 constitute an expansion / contraction mechanism that expands / contracts the link mechanism 34. The inside of the hydraulic cylinder 136 is divided into a first chamber 136 a and a second chamber 136 b by one end of the rod 138.

  The second chamber 136b of the hydraulic cylinder 136 and the pump 112 are connected by a hydraulic pipe, and a valve 110, a pressure gauge 102, and an accumulator 104 are provided in the order of the pump 112 from the pump 112 side. The pump 112 is a drive source for applying pressure to the second chamber 136b. The pump 112 is maintained at a predetermined pressure.

  The valve 110 communicates or shuts off the hydraulic piping according to the opening and closing thereof, and the opening and closing of the valve 110 is controlled by the control unit 26. When the valve 110 is opened, the hydraulic pipe is connected, and the hydraulic pressure of the pump 112 is applied to the second chamber 136b. When the valve 110 is closed, the hydraulic piping is shut off and the hydraulic pressure of the pump 112 is confined. That is, the hydraulic pressure in the second chamber 136 b of the hydraulic cylinder 136 is controlled by opening and closing the valve 110. The pressure gauge 102 detects the pressure value of the hydraulic cylinder 136 and transmits the detection result to the control unit 26.

  The pressure value of the hydraulic cylinder 136 detected by the pressure gauge 102 indicates the load by which the link mechanism 34 lifts the work implement 12. That is, the load for lifting the work implement 12 can be adjusted by adjusting the pressure value of the hydraulic cylinder 136. When the load generated in the hydraulic cylinder 136 is larger than the lifting load of the work machine 12, the hydraulic cylinder 136 contracts, and when the load is smaller, the hydraulic cylinder 136 extends. Therefore, the hydraulic cylinder 136 can be expanded and contracted by controlling the opening and closing of the valve 110.

  The expansion / contraction control unit 68 controls the load of the work machine 12 on the soil by controlling the pressure value detected by the pressure gauge 102 to be the third target load calculated by the target load deriving unit 66.

  By the way, when the vehicle side link 34 a moves up and down due to the shaking of the vehicle 10, an external force is transmitted from the link mechanism 34 to the hydraulic cylinder 136. At this time, the accumulator 104 absorbs the load, and the load is converted into an expansion / contraction operation of the hydraulic cylinder 136. That is, the accumulator 104 functions as a load absorption unit that is interposed in the hydraulic cylinder 136 and absorbs a load transmitted from the vehicle body 10a and the work implement 12 to the link mechanism 34 and converts it into an expansion / contraction operation. That is, the accumulator 104 functions in the same manner as the spring member 42 of the work machine connection device 18 of the embodiment.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements, and such modifications are also within the scope of the present invention.

  In the embodiment, the mode in which the softness of the soil is detected by the softness detection sensor 24 is shown, but the present invention is not limited to this mode. For example, the driver may determine the softness of the soil and input the softness of the soil to the control unit 26. The driver determines the hardness of the soil according to the elapsed time and the weather since the water flowed into the paddy field.

  In the embodiment, an embodiment in which one end of the hydraulic cylinder 36 is fixed to the vehicle body 10 a is shown. However, for example, one end of the hydraulic cylinder 36 may be fixed to the fourth shaft portion 50. Thereby, the expansion and contraction of the hydraulic cylinder 36 can be applied to the link mechanism 34 as it is.

  DESCRIPTION OF SYMBOLS 10 Vehicle, 10a Car body, 12 Working machine, 14 Float, 16 Direct seeding machine, 18 Working machine coupling device, 20 Groove part, 21 Notch part, 22 Covering part, 24 Hardness detection sensor, 26 Control part, 28 Expansion / contraction adjustment mechanism, 30 tilt angle sensor, 32 shaft support, 34 link mechanism, 34b work equipment side link, 34a vehicle side link, 34c first connection link, 34d second connection link, 36 hydraulic cylinder, 38 rod, 40 spring connection part, 42 Spring member, 44 First shaft portion, 46 Second shaft portion, 48 Third shaft portion, 50 Fourth shaft portion, 52 Spring length sensor, 60 Hardness / softness acquisition portion, 62 Inclination angle acquisition portion, 64 Load acquisition portion, 66 Target load deriving section, 67 weight estimation section, 68 expansion / contraction control section, 70 work implement coupling device, 72 tillage layer, 4 mud layer, 102 a pressure gauge, 104 accumulator.

Claims (4)

A work machine coupling device for coupling a work machine that works on soil to a vehicle body,
A link mechanism that connects the vehicle body and the work implement, and can extend and contract between the vehicle body and the work implement;
An expansion and contraction mechanism for expanding and contracting the link mechanism;
A control unit for controlling expansion and contraction of the expansion and contraction mechanism ,
The link mechanism is configured to press the working machine against soil or lift the working machine by stretching the telescopic mechanism.
The telescopic mechanism absorbs load transmitted to the link mechanism from the vehicle body and the working machine, have a load absorbing portion for converting the expansion and contraction of the telescopic mechanism,
The controller is
A load acquisition unit for acquiring a lifting load of the working machine by the extension mechanism;
An inclination angle acquisition unit for acquiring an inclination angle of the link mechanism with respect to the vehicle body;
A weight estimation unit that estimates the weight of the work implement based on the tilt angle and the lifting load;
A target load deriving unit for deriving a target load to be applied to the work implement based on the estimated weight of the work implement;
And a telescopic control unit that expands and contracts the telescopic mechanism according to the target load . The control unit has a hardness / softness acquisition unit that acquires the hardness of soil .
The target load deriving unit, working machine attachment device of claim 1, wherein the benzalkonium to derive a target load to be applied to the working machine according to the hardness degree.   The target load deriving unit derives the target load such that when the hardness is relatively high, the load applied to the soil by the work implement is larger than when the hardness is relatively low. The work machine coupling device according to claim 2, wherein The expansion / contraction mechanism has a hydraulic cylinder that can expand and contract,
The load absorbing portion, the working machine coupling device according to any one of claims 1 to 3, wherein said fluid is a pressure cylinder a spring member for indirectly connected to the link mechanism.

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