Combine harvester and method for controlling the combine harvester

Abstract

To provide a combine capable of inhibiting grain culm from being left unreaped by lifting and lowering of a reaping part and suppressing thrust of the reaping part into a ground.SOLUTION: A combine includes a reaping part provided so as to be lifted and lowered with respect to a travelling machine body, a reaping height detection device for detecting a reaping height, which is a height of the reaping part, and a control device for controlling the height of the reaping part so that the reaping height (reaping height detection value R1) detected by the reaping height detection device becomes a reaping height target value R0 set beforehand. The control device controls the height of the reaping part so that the reaping height detected by the reaping height detection device becomes the reaping height target value R0 when the reaping height detection value R1 is greater than the reaping height target value R0 or the value is lower than the reaping height target value R0, and reduces a vehicle speed of the travelling machine body.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a combine harvester having a height-adjustable cutting unit and a method for controlling a combine harvester. [Background technology]

[0002] Generally, a combine harvester is equipped with a reaping unit at the front of the traveling body and a threshing unit on the traveling body, and while traveling, the reaping unit harvests stalks and the threshing unit threshes the stalks. Conventionally, some combine harvesters have a reaping unit that can be raised and lowered relative to the traveling body and a cutting height detection device to control the cutting height, which is the height of the reaping unit from the ground. In such a configuration, the operation of a lifting device such as a hydraulic cylinder that raises and lowers the reaping unit is controlled based on a detection signal from the cutting height detection device, and the cutting height is automatically controlled (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a technology for setting a control target value for the cutting height and automatically controlling the elevation of the cutting unit so that the cutting height becomes the control target value. Specifically, Patent Document 1 discloses a control content for setting the control target value of the cutting height low when the drive speed of the cutting unit is increased to perform cutting work in order to prevent any grass from being left uncut. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-137424 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in the automatic control of the mowing height, for example, if the vehicle speed of the traveling machine body is set to a relatively high speed, there is a risk that fallen stalks will be left uncut when the mowing unit is raised or lowered, or that the mowing unit will dig into the ground. Here, digging into the ground means that the grass-splitting board or the like provided at the front of the mowing unit digs into the ground, which may cause the cutting blade of the mowing unit to become clogged with soil or crops, reducing work efficiency.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a combine and a control method for a combine that can prevent crops from being left uncut or the cutting part from crashing into the ground when the cutting part rises and falls. [Means for solving the problem]

[0007] The combine harvester of the present invention is a combine harvester comprising a cutting unit that is capable of being raised and lowered relative to a running body, a cutting height detection device for detecting the cutting height, which is the height of the cutting unit, and a control device for controlling the height of the cutting unit so that the cutting height detected by the cutting height detection device becomes a predetermined target value, and when the cutting height detected by the cutting height detection device is above the target value or below the target value, the control device controls the height of the cutting unit so that the cutting height detected by the cutting height detection device becomes the target value and reduces the vehicle speed of the running body.

[0008] In another aspect of the combine of the present invention, the control device has, as control modes for the height of the cutting part, a normal mode and a lowering mode in which the target value is smaller than that of the normal mode, and, provided that the control mode is the lowering mode, controls the height of the cutting part so that the cutting height detected by the cutting height detection device becomes the target value, and also reduces the vehicle speed of the traveling body.

[0009] In another aspect of the combine of the present invention, in the combine, the control device reduces the vehicle speed when the cutting height detected by the cutting height detection device exceeds a value obtained by adding a predetermined value to the target value or falls below a value obtained by subtracting a predetermined value from the target value.

[0010] In another aspect of the combine of the present invention, the control device of the combine increases the degree of deceleration of the vehicle speed the greater the amount by which the cutting height detected by the cutting height detection device exceeds or falls short of the target value.

[0011] In another aspect of the combine of the present invention, in the combine, when the vehicle speed when lowering or raising the cutting part exceeds a predetermined set speed, the control device reduces the vehicle speed so that the vehicle speed becomes the set speed.

[0012] In another aspect of the combine of the present invention, the control device is configured to increase the degree of deceleration of the vehicle speed the greater the difference between the vehicle speed and the set speed when lowering or raising the cutting part.

[0013] In another aspect of the combine of the present invention, in the combine, the set speed is set to be lower as the amount by which the cutting height detected by the cutting height detection device exceeds or falls short of the target value increases.

[0014] In a combine harvester according to another aspect of the present invention, the control device increases the speed at which the cutting part is raised as the degree of deceleration of the vehicle speed increases.

[0015] In a combine harvester according to another aspect of the present invention, the control device is configured to slow down the speed at which the cutting part is lowered as the degree of deceleration of the vehicle speed increases.

[0016] The control method for a combine harvester of the present invention is a control method for a combine harvester that detects the cutting height, which is the height of the cutting part, and controls the height of the cutting part so that the detected cutting height becomes a predetermined target value.When the detected cutting height exceeds the target value or is below the target value, the height of the cutting part is controlled so that the detected cutting height becomes the target value, and the vehicle speed is reduced. Effect of the Invention

[0017] According to the present invention, it is possible to prevent grass from being left uncut or the cutting unit from crashing into the ground when the cutting unit is raised and lowered. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a left side view of a combine harvester according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a right side view of a combine harvester according to one embodiment of the present invention. [Diagram 3] FIG. 2 is a plan view showing the configuration of the reaping section of a combine harvester according to one embodiment of the present invention. [Figure 4] This is a left side view showing the configuration of a grass dividing section and a cutting height detection device according to one embodiment of the present invention. [Diagram 5] 1 is a perspective view showing a configuration of a cutting height detection device according to an embodiment of the present invention; [Figure 6] 1 is a left side view showing a cutting height detection device according to an embodiment of the present invention. [Figure 7] 1 is a plan view showing a cutting height detection device according to an embodiment of the present invention. [Figure 8] 2 is a block diagram showing a control configuration of a combine harvester according to one embodiment of the present invention. FIG. [Figure 9] 4 is a flowchart showing a first control mode by a control device according to an embodiment of the present invention. [Figure 10] 5 is a flowchart showing a second control mode by the control device according to the embodiment of the present invention. [Figure 11]6 is a flowchart showing a third control mode by the control device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention aims to prevent the raising and lowering of the cutting unit from leaving any grass behind or from crashing into other land areas, by controlling the height of the cutting unit and vehicle speed based on a detection value of the cutting height, which is the height of the cutting unit, in a combine harvester having a height-adjustable cutting unit. The following describes an embodiment of the present invention.

[0020] [Overall configuration of the combine] First, the overall configuration of a combine harvester 1 according to this embodiment will be described with reference to Figures 1 and 2. In the following description, the left and right sides of the combine harvester 1 facing the front (left side in Figure 1) are the left and right sides of the combine harvester 1, respectively.

[0021] 1 and 2, the combine harvester 1 according to this embodiment includes a traveling section 2 configured as a crawler-type traveling device having a pair of left and right crawler sections 3, 3, and a traveling body 4 supported by the traveling section 2. The traveling body 4 includes a frame-shaped structural part of the vehicle body of the combine harvester 1. The combine harvester 1 includes an engine 11 mounted on the traveling body 4 as a drive source.

[0022] A reaping unit 5 is provided at the front of the traveling body 4, which harvests and collects stalks of rice, wheat, etc. in the field. A threshing unit 6 which threshes the stalks harvested by the reaping unit 5, and a grain tank 7 which stores the grains removed from the threshing unit 6 are provided side by side on the traveling body 4. The threshing unit 6 is located on the left side of the body, and the grain tank 7 is located on the right side of the body. The combine harvester 1 travels on the traveling unit 2 while harvesting stalks with the reaping unit 5 and threshing with the threshing unit 6.

[0023] Each crawler unit 3 constituting the traveling unit 2 has a track frame 3a extending in the front-rear direction below the traveling body 4, various rotating bodies such as a drive sprocket 3b supported by the track frame 3a, and a track 3c wound around these rotating bodies. The crawler unit 3 is driven by the power of the engine 11 transmitted to the drive sprocket 3b.

[0024] The reaping unit 5 is driven by driving force from the engine 11, harvests the stalks, and transports the harvested stalks to the threshing unit 6, etc. The reaping unit 5 is provided in front of the traveling body 4 across substantially the entire width of the combine harvester 1. The reaping unit 5 is provided so as to be able to rise and fall relative to the traveling body 4. Note that Fig. 2 shows the reaping unit 5 in a state where it has been lowered from the state shown in Fig. 1.

[0025] The threshing section 6 has a threshing drum 6a with a rotation axis extending in the front-rear direction, and a stew supplying device provided to the left of the threshing drum 6a. The stew supplying device holds the base of the stew harvested by the harvesting section 5 and transports the stew rearward in a lying position with the ears facing the threshing drum 6a. The stew supplying device is a feed chain 6 wound around multiple sprockets with a rotation axis extending in the left-right direction. c and a culm supply clamping body 6 which cooperates with this to clamp the base of the culm. b The present invention is configured to include the following.

[0026] Below the threshing section 6 on the traveling machine body 4, a sorting section 8 is provided which sorts the material threshed by the threshing section 6. The sorting section 8 has a rocking sorting device 8a, a wind sorting device and a grain conveying device. The sorting section 8 rocks and sorts the material that has fallen from the threshing section 6 using the rocking sorting device 8a, and wind sorts the material after rocking and sorting using the wind sorting device. The sorting section 8 conveys grains from the material after wind sorting to the right towards the grain tank 7 using the grain conveying device, and blows straw dust, dust and the like backwards using the wind sorting device and discharges them outside the machine body. The grains conveyed by the grain conveying device towards the grain tank 7 are stored in the grain tank 7.

[0027] A discharge auger 9 is rotatably provided at the rear right end of the traveling body 4 as a grain discharge device that discharges grains from the grain tank 7 to the outside. The discharge auger 9 has a discharge port 9a at its tip, and discharges grains stored in the grain tank 7 from the discharge port 9a. The grains discharged from the discharge port 9a are dumped into the bed of a truck, a container, or the like.

[0028] On the traveling machine body 4, behind the threshing section 6, there is provided a straw waste processing section 10 which processes the straw waste after threshing by the threshing section 6. The straw waste processing section 10 has a straw waste conveying device 10a and a straw waste cutting device 10b. The straw waste conveying device 10a conveys the threshed stump (stump) by the threshing section 6 rearward and discharges it outside the machine body or conveys it to the straw waste cutting device 10b. The straw waste cutting device 10b cuts the stump transported from the straw waste conveying device 10a and discharges it outside the machine body.

[0029] On the traveling body 4, to the right of the reaping unit 5 and in front of the grain tank 7, a driver's unit 14 covered by a cabin 13 is provided. A handle unit 15 serving as a steering operation unit is provided in front of the driver's unit 14, and a driver's seat 16 is provided behind the handle unit 15. Various operating tools including a main shift lever 17 are disposed to the side of the driver's seat 16.

[0030] A prime mover unit including an engine 11 is provided below the driving unit 14. The engine 11 is, for example, a diesel engine. The power of the engine 11 is transmitted to various devices provided in each part of the combine 1 via a transmission or the like.

[0031] The reaping unit 5 will be described with reference to Figures 1 to 3. The reaping unit 5 has a reaping support machine frame 20 as a reaping frame, and is configured by supporting a grass dividing board 21, a lifting device 22, a raking device 23, a cutting blade device 24, a stalk transport device 25, etc. on the reaping support machine frame 20. Each device of the reaping unit 5 operates by transmitting power from the engine 11.

[0032] The grass dividing board 21 constitutes the grass dividing section 50 of the cutting section 5, is provided at the front end of the cutting section 5, has a tapered shape, and divides the culms growing in the field. The lifting device 22 is provided on the rear side of the grass dividing board 21, and lifts up fallen culms by operating multiple tines 22a connected by a chain.

[0033] The raking device 23 is provided behind the lifting device 22, and includes a chain-driven conveying mechanism 23a and a rotary packer 23b, and raks in the stalks. In addition, in Fig. 3, only the components of the raking device 23 provided at the left end are shown, and the other components are omitted.

[0034] The cutting blade device 24 is a clipper-type device that cuts the base of the raised culm. The culm conveying device 25 is a device that conveys the culm that has been cut. It joins together multiple culm rows, clamps and conveys them upward and rearward, and conveys them to the feed chain 6 of the threshing section 6. c The material is handed over to the starting end of the product in a horizontal position.

[0035] As shown in Fig. 1, the reaping support machine frame 20 is supported by a support frame 26 arranged in a downwardly-descending manner on the front side of the traveling machine body 4. The support frame 26 is provided in approximately the center in the left-right direction of the machine body, and the reaping support machine frame 20 is provided on the front side of the support frame 26.

[0036] As shown in Fig. 3, the reaping support machine frame 20 has a horizontal frame 31 extending in the left-right direction of the machine body, and a plurality of grass dividing frames 32 extending forward from the horizontal frame 31. The reaping support machine frame 20 is supported by the support frame 26 at the horizontal frame 31.

[0037] The horizontal frame 31 is a straight frame part made of square pipe-shaped members. The grass division frame 32 is a frame part made of round pipe-shaped members, has a predetermined bent or curved shape, and extends in the front-rear direction in a plan view. The grass division frame 32 is supported in a cantilever manner by fixing and supporting the rear end or rear part to the horizontal frame 31.

[0038] The multiple grass dividing frames 32 are arranged in parallel at a predetermined interval in the left-right direction. The number of grass dividing frames 32 is one more than the number of cutting rows of the combine harvester 1. The combine harvester 1 in this embodiment is a seven-row cutter, and eight grass dividing frames 32 are provided. Of the eight grass dividing frames 32, the grass dividing frame 32A located at the left end has a different shape from the other multiple (seven) grass dividing frames 32.

[0039] A lifting device 22 is arranged between adjacent grass dividing frames 32 on the left and right, for a total of seven lifting devices 22. The lower part of the lifting device 22 is connected and supported to the front of each grass dividing frame 32 via a support stay or the like (not shown). A grass dividing board 21 is also attached to the front end of each grass dividing frame 32. The multiple grass dividing boards 21 include two types of grass dividing boards 21, one relatively large and one relatively small, which are provided in a predetermined arrangement.

[0040] The reaping unit 5 having the above-mentioned configuration is attached to the traveling machine body 4 so as to be rotatable about a predetermined axis via a reaping lifting cylinder 18 serving as a lifting device (see FIG. 1). In other words, the reaping unit 5 is provided so as to be able to be raised and lowered relative to the traveling machine body 4 by a rotational action caused by the extension and contraction of the reaping lifting cylinder 18. The reaping lifting cylinder 18 is a hydraulic cylinder, and is provided between the traveling machine body 4 and the support frame 26. The rear end of the support frame 26 is supported so as to be rotatable about a left-right axis relative to the traveling machine body 4 as a rotation fulcrum for the lifting and lowering action of the reaping unit 5 by the reaping lifting cylinder 18.

[0041] As described above, the combine harvester 1 has the reaping unit 5 arranged to be liftable and lowerable relative to the traveling body 4. The combine harvester 1 is equipped with a cutting height detection device 40 and a control device 200 (see FIG. 8) in order to control the cutting height (height above the ground), which is the height of the reaping unit 5 from the ground surface G1. In this configuration, the control device 200 controls the operation of the reaping lifting cylinder 18 that lifts and lowers the reaping unit 5 based on a detection signal from the cutting height detection device 40, thereby automatically controlling the cutting height.

[0042] The operation of the cutting lift cylinder 18 is controlled by controlling the operation of a solenoid valve, which is a control valve. The control device 200 controls the cutting height by controlling the operation of the control valve of the cutting lift cylinder 18 based on a detection signal from the cutting height detection device 40.

[0043] The automatic control of the cutting height controls the operation of the control valve of the cutting lifting cylinder 18 so as to maintain the cutting height of the cutting unit 5 at a set value based on a detection signal from the cutting height detection device 40, and automatically controls the lifting and lowering of the cutting unit 5. The driving unit 14 is provided with an operation unit for adjusting the cutting height, and for example, during automatic control of the cutting height, control is performed that gives priority to adjustment of the cutting height by operating the operation unit.

[0044] In the automatic control of the mowing height, the control device 200 controls the height of the mowing unit 5 so that the mowing height detected by the mowing height detection device 40 becomes a preset target value (hereinafter referred to as the "mowing height target value"). That is, when the detected mowing height is below the mowing height target value, the control device 200 raises the mowing unit 5, and when the detected mowing height is above the mowing height target value, the control device 200 lowers the mowing unit 5, thereby controlling the elevation of the mowing unit 5 so that the height of the mowing unit 5 is maintained at a height corresponding to the mowing height target value.

[0045] As described above, the combine harvester 1 includes the cutting unit 5 having the grass dividing section 50 including the grass dividing board 21 and arranged so as to be able to rise and fall with respect to the traveling body 4, the cutting height detection device 40 for detecting the cutting height, which is the height of the cutting unit 5, and the control device 200 for controlling the height of the cutting unit 5 so that the cutting height detected by the cutting height detection device 40 becomes the target cutting height value. In this embodiment, the cutting height detection device 40 is disposed behind the grass dividing board 21A located at the left end of the eight grass dividing boards 21. The leftmost grass dividing board 21A is supported by the grass dividing frame 32A located at the left end. The leftmost grass dividing board 21A is the relatively larger grass dividing board 21 of the two types of grass dividing boards 21.

[0046] [Configuration of cutting height detection device] The configuration of the cutting height detection device 40 will be described with reference to Figures 4 to 7. As shown in Figures 4 to 7, the cutting height detection device 40 comprises a device main body 41, a grounding body 42, a cutting height sensor 43, and a unit support 44 which is a device main body support member. In the cutting height detection device 40, the device main body 41, the grounding body 42, and the cutting height sensor 43 form an integrated sensor unit 45, and this sensor unit 45 is supported by the unit support 44 so as to be rotatable about an axis in the left-right direction. The unit support 44 is supported by the grass dividing section 50 so as to be rotatable about an axis in the front-rear direction.

[0047] The height-of-cutting detection device 40 as a whole is supported rotatably about an axis in the front-to-rear direction relative to the grass dividing section 50, and the sensor unit 45 is supported rotatably about an axis in the left-to-right direction relative to the unit support body 44. Rotation of the height-of-cutting detection device 40 about its front-to-rear axis and rotation of the sensor unit 45 about its left-to-right axis are performed in response to an external force acting on the height-of-cutting detection device 40. In the following, a state in which no external force is acting on the height-of-cutting detection device 40 is defined as a reference state, and unless otherwise specified, the height-of-cutting detection device 40 in the reference state will be described.

[0048] In the sensor unit 45, the device main body 41 has a configuration in which various gears, springs, etc. are supported on predetermined shafts inside a case 51 made of, for example, a metal casting. The case 51 has a left-right two-part structure consisting of a right case body 52 forming the main body of the case 51 and a left case body 53 covering the left side of the right case body 52 like a lid. The right case body 52 and the left case body 53 are fixed to each other by fixing bolts 55 at four points around the periphery of the case 51 in a side view. The case 51 has a curved shape with the upper side being convex and the lower side being concave in a side view (see FIG. 6).

[0049] In the sensor unit 45, the grounding body 42 extends downward from the rear side of the rear end of the case 51. The cutting height sensor 43 is provided in a manner such that it is attached to the right side surface of the case 51.

[0050] The unit support 44 is a member in which a strip-shaped plate member is bent to have a predetermined shape in a plan view, and extends in the front-rear direction. The unit support 44 has a left side portion 44a that is elongated in the front-rear direction, a front portion 44b that is formed so as to form a right angle from the front end of the left side portion 44a toward the right, a right front side portion 44c that is formed so as to form a right angle from the right end of the front portion 44b toward the rear, and a rear portion 44d that is formed so as to form a right angle from the rear end of the left side portion 44a toward the right. The unit support 44 is open at the top and bottom, and has a shape that is long in the front-rear direction in a plan view due to the left side portion 44a, the front portion 44b, the right front side portion 44c, and the rear portion 44d, and has a shape that is long in the front-rear direction in a plan view, and most of the right rear side is open.

[0051] The sensor unit 45 is provided relative to such a unit support 44 so as to be located at the front of the space surrounded by the unit support 44. Almost the entire sensor unit 45 is located within a rectangular range that follows the outer shape of the unit support 44 in a plan view.

[0052] The sensor unit 45 has a front end of the case 51 located immediately behind the front surface 44b, between the front end of the left side surface 44a and the front right side surface 44c. In addition, approximately the rear half of the left side surface 44a is located rearward of the rear end of the case 51 in the front-rear direction.

[0053] Each part of the sensor unit 45 will be described. The device body 41 is provided on a front fixed shaft 61, which is a first shaft, so as to be rotatable up and down (see FIG. 7). The front fixed shaft 61 is a support shaft whose axial direction is in the left-right direction, and supports the sensor unit 45 so as to be rotatable around a first axis P1.

[0054] The front fixed shaft 61 is located in the device body 41 near the front end of the case 51. The front fixed shaft 61 extends leftward from the right front side surface 44c with its right end fixed to the right front side surface 44c of the unit support 44. In other words, the front fixed shaft 61 is a fixed shaft supported in a cantilever manner relative to the right front side surface 44c. Note that the front fixed shaft 61 may be any shaft fixed to the unit support 44. The front fixed shaft 61 is supported rotatably relative to the case 51. In other words, the case 51 is supported rotatably relative to the front fixed shaft 61.

[0055] In this way, the sensor unit 45 is provided so as to be vertically rotatable in a cantilevered state with the left-right direction as the axial direction relative to the front fixed shaft 61, which is a fixed shaft fixed to the unit support 44 (see arrow A1 in FIG. 6). In other words, the unit support 44 supports the device body 41 of the sensor unit 45 by the front fixed shaft 61 so as to be vertically rotatable.

[0056] With respect to the rotation of the sensor unit 45 around the first axis P1 relative to the unit support 44, the sensor unit 45 is biased in a downward rotation direction by a case return member, which is an elastic member such as a spring provided in the case 51. The case return member is, for example, a torsion spring having a coil-shaped portion and extensions at both ends thereof. In this case, the case return member is provided in a state in which the front fixed shaft 61 penetrates the coil-shaped portion, one extension is engaged with the front fixed shaft 61 side, and the other extension is engaged with the case 51 side, and applies a force that presses the case 51 downward toward the front fixed shaft 61 side. As a result, the sensor unit 45 is biased in a direction of rotating downward around the axis of the front fixed shaft 61.

[0057] Meanwhile, with regard to rotation of the sensor unit 45 relative to the unit support 44, downward rotation of the sensor unit 45 is restricted in the reference state position by a locking protrusion 53b provided on the case 51. The locking protrusion 53b is formed at the upper end of the front-rear center part of the left case body 53 and protrudes leftward as part of the left case body 53. In the reference state, the locking protrusion 53b abuts against the upper edge of the left side surface part 44a of the unit support body 44, thereby disabling the sensor unit 45 from rotating downward relative to the unit support body 44.

[0058] In this way, the sensor unit 45 is restricted from rotating downward from the reference state relative to the unit support 44 while being biased in the downward rotation direction with respect to rotation about the front fixed shaft 61. Therefore, when an external force from the ground G1 acts on the sensor unit 45 to rotate the sensor unit 45 upward about the front fixed shaft 61, the sensor unit 45 rotates upward against the biasing force of the case returning member, and when the external force is released, the sensor unit 45 automatically rotates downward due to the biasing force of the case returning member and returns to the reference state position due to the locking action of the locking protrusion 53b.

[0059] The grounding body 42 is rotatably supported by a rear rotating shaft 62, which is a second shaft located behind the front fixed shaft 61 with respect to the device body 41. The rear rotating shaft 62 is a support shaft whose axial direction is in the left-right direction, and supports the grounding body 42 rotatably with respect to the case 51 of the device body 41 about the second axis P2.

[0060] The rear rotating shaft 62 is located near the rear end of the case 51, and is supported so as to be rotatable relative to the case 51. The grounding body 42 is fixed to a portion of the rear rotating shaft 62 that protrudes to the right from the case 51. The grounding body 42 has a grounding body main body portion 42a that is a portion that extends downward from the device main body 41, and a support arm portion 42b that is a support portion for the rear rotating shaft 62. The grounding body main body portion 42a and the support arm portion 42b are both plate-like portions having a predetermined shape.

[0061] The grounding body main body 42a is a spatula-shaped portion that gradually widens in width (dimension in the left-right direction) from the top to the bottom. The grounding body main body 42a is bent at an obtuse angle with the front side being convex in side view. The support arm 42b is a vertical wall-shaped portion that is bent at an obtuse angle, and extends from the upper end of the grounding body main body 42a located immediately behind the case 51 to the right front side along the case 51 and is fixed to the rear rotating shaft 62 (see FIG. 7). The right end of the rear rotating shaft 62 penetrates the front part of the support arm 42b, whose plate thickness direction is the left-right direction, and the support arm 42b is fastened and fixed to the rear rotating shaft 62 by a nut 68 or the like.

[0062] In this manner, the grounding body 42 is fixed to the rear rotating shaft 62 and rotates integrally with the rear rotating shaft 62 about the second axis P2. The grounding body 42 is provided so as not to interfere with the case 51 within its rotation range. With regard to the rotational position of the grounding body 42, the position of the grounding body 42 in the cutting height detection device 40 in the reference state is defined as the reference position.

[0063] The ground contact body 42 rotates as follows relative to the device body 41 around the rear rotation shaft 62. That is, with the tip of the ground contacting the ground G1, the ground contact body 42 rotates (rotates backward) to move the tip side backward due to drag resistance (ground sliding resistance) from the ground G1 caused by the combine harvester 1 moving forward (see arrow C1 in FIG. 6). On the other hand, the ground contact body 42 rotates (rotates forward) to move the tip side forward due to ground sliding resistance caused by the combine harvester 1 moving backward (see arrow C2 in FIG. 6).

[0064] The cutting height sensor 43 is a sensor that detects the amount of rotation of the grounding body 42 about the rear rotating shaft 62. The cutting height sensor 43 is provided with respect to an intermediate rotating shaft 70, which is the third shaft provided in the cutting height detection device 40, and detects the amount of rotation of the grounding body 42 about the rear rotating shaft 62 from the amount of rotation of the intermediate rotating shaft 70.

[0065] The intermediate rotating shaft 70 is a support shaft whose axial direction is in the left-right direction, and is supported so as to be rotatable relative to the case 51 of the device main body 41 about a third axis P3. The intermediate rotating shaft 70 is located midway between the front fixed shaft 61 and the rear rotating shaft 62 in the front-rear direction.

[0066] The cutting height sensor 43 is a rotary type potentiometer, and detects the rotational position of the grounding body 42 via the intermediate rotating shaft 70 and the rear rotating shaft 62. The cutting height sensor 43 is located between the front fixed shaft 61 and the rear rotating shaft 62 in the front-to-rear direction. The cutting height sensor 43 is located on the right side surface of the right case body 52, and is fixed to the right case body 52 by bolts 73 at two points, one at the front and one at the rear.

[0067] The cutting height sensor 43 is connected to the right end of the intermediate rotating shaft 70 and directly detects the rotational position of the intermediate rotating shaft 70 about the third axis P3, using the intermediate rotating shaft 70 as a detection axis. The cutting height sensor 43 has a signal line 43a extending upward from its main body and connected to the control device 200. Note that the cutting height sensor 43 may be configured to have a connector portion in the main body to which the signal line is connected, instead of the signal line 43a.

[0068] The intermediate rotating shaft 70 rotates by receiving the rotational power of the rear rotating shaft 62 accompanying the rotation of the grounding body 42. The intermediate rotating shaft 70 receives the rotational power of the rear rotating shaft 62 via gears or the like provided for each of the rear rotating shaft 62 and the intermediate rotating shaft 70. The rotation of the intermediate rotating shaft 70 is detected by the cutting height sensor 43. The grounding body 42 uses a grounding body returning member which is an elastic member such as a spring provided within the case 51, and is provided so that the grounding body 42 is positioned at a predetermined reference position for rotation around the rear rotating shaft 62 in a state where it is not subjected to the action of an external force by setting the biasing force (torque) of each of the case returning member and the grounding body returning member.

[0069] In the height-of-cut detection device 40 having the above-described configuration, the grounding body 42 is arranged to rotate about the rear pivot shaft 62 with respect to the device body 41, which is in a state where rotation about the front fixed shaft 61 is stopped, when the grounding body 42 is located rearward of the reference position, for example, when the combine harvester 1 moves forward and the like, when the grounding body 42 is pressed from the front and rotates rearward from the reference position, the device body 41 does not rotate about the front fixed shaft 61, and only the grounding body 42 rotates about the rear pivot shaft 62 relative to the device body 41.

[0070] The cutting height sensor 43 detects the amount of rotation of the grounding body 42 backward from the reference position. That is, the rearward relative rotation of the grounding body 42 with respect to the device body 41 from a state in which the grounding body 42 is in the reference position is detected by the cutting height sensor 43 as the rotation for detecting the cutting height.

[0071] On the other hand, with regard to the relative rotation of the grounding body 42 with respect to the device body 41, the rotation of the grounding body 42 forward from the reference position is accompanied by the upward rotation of the case 51. That is, when the grounding body 42 rotates forward from the reference position, the device body 41 as a whole rotates upward about the front fixed shaft 61 in conjunction with the rotation of the grounding body 42. Here, when the grounding body 42 rotates forward from the reference position relative to the device body 41, the intermediate rotating shaft 70 does not rotate, and the cutting height sensor 43 does not detect the rotation of the intermediate rotating shaft 70.

[0072] As described above, the cutting height detection device 40 is configured so that the cutting height sensor 43 detects the amount of rotation of the grounding body 42 when the grounding body 42 is rotated rearward from the reference position relative to the device body 41.

[0073] By using the cutting height detection device 40 having the above-mentioned configuration, the combine harvester 1 detects the height (cutting height) of the cutting part 5 based on the detection signal from the cutting height sensor 43. As described above, the cutting height detection device 40 detects the rearward rotation of the ground contact body 42, and therefore detects the cutting height mainly when the body of the combine harvester 1 moves forward.

[0074] In the cutting height detection device 40, the cutting height sensor 43 detects the height of the grass dividing board 21 from the ground G1, that is, the cutting height, by detecting the rotational position of the intermediate rotating shaft 70, which rotates in conjunction with the rotation of the grounding body 42. The detection signal of the cutting height sensor 43 is sent to the control device 200 from the signal line 43a. The control device 200 receives the detection signal from the cutting height sensor 43, and operates the cutting lifting cylinder 18 based on the detection signal to adjust the cutting height so that the cutting height calculated from the detection result is maintained at the cutting height target value.

[0075] [Support structure of cutting height detection device] The support structure of the cutting height detection device 40 will be described with reference to Figures 4 to 7. The cutting height detection device 40 is supported by the support structure of the unit support body 44 relative to the grass dividing section 50 so as to be rotatable so as to swing left and right about an axis O1 along the front-rear direction.

[0076] As shown in Figures 4 to 7, the grass dividing section 50 includes a grass dividing frame 32 at the left end provided at the bottom of the cutting section 5, a grass dividing board 21 provided in front of the grass dividing frame 32, and a support frame 100 fixed to the grass dividing frame 32. Here, the grass dividing board 21 and grass dividing frame 32 related to supporting the cutting height detection device 40 are the grass dividing board 21A and grass dividing frame 32A located at the left end, respectively (see Figure 3).

[0077] The grass dividing frame 32 has, from the rear to the front, a rear inclined portion 101 which is a downward sloping portion at the front, an intermediate inclined portion 102 which is an upward sloping portion at the front that forms an obtuse angle together with the rear inclined portion 101, and a front inclined portion 103 which is an upward sloping portion at the front that forms an acute angle together with the intermediate inclined portion 102. The grass dividing frame 32 has the intermediate portion of the rear inclined portion 101 positioned above the left end of the horizontal frame 31, and the rear inclined portion 101 is fixed to the horizontal frame 31 which constitutes the harvesting support machine frame 20 via a support member 105 fixed on the left end of the horizontal frame 31.

[0078] The support frame 100 is a frame portion made of a round pipe-shaped member and has a predetermined bent or curved shape. From the rear side to the front side, the support frame 100 has a rear inclined portion 111 which is an inclined portion that slopes downward toward the front, a horizontal portion 112 which is a horizontal portion that forms an obtuse-angled corner together with the rear inclined portion 111, a front inclined portion 113 which is an inclined portion that slopes upward toward the front and forms an obtuse-angled corner together with the horizontal portion 112, and an upright portion 114 which rises diagonally upward toward the rear so as to form an obtuse-angled corner together with the front inclined portion 113.

[0079] The rear end of the rear inclined portion 111, which is the rear end of the support frame 100, is fixed by welding or the like to the front side of the lower part of the intermediate inclined portion 102 of the grass dividing frame 32. The standing portion 114 has an inclination angle that is approximately parallel to the front inclined portion 103 of the grass dividing frame 32 in a side view, and is fixed to the front inclined portion 103 by welding or the like in a state along the rear side of the front inclined portion 103. The support frame 100 is fixed to the grass dividing frame 32 on both the front and rear sides by welding or the like, and together with the grass dividing frame 32, it forms a closed frame portion that is polygonal in side view.

[0080] The grass dividing board 21 has a grass dividing board main body 121 and a rib board section 122 provided on the rear side of the grass dividing board main body 121. The grass dividing board main body 121 has a pointed shape that gradually narrows from the rear side to the front side in front and plan views, and has a curved shape that slopes downward at the front and has a convex lower rear side in side view. The rib board section 122 is a plate-shaped part whose thickness direction is the left-right direction, and is provided as an integral part of the grass dividing board main body 121 on the rear side of the front board section of the grass dividing board main body 121.

[0081] The grass dividing section 50 also includes a hitch 125 as a grass dividing board support member provided on the rear side of the grass dividing board 21. The hitch 125 is a longitudinal plate-like member that is attached to the grass dividing board 21 and fixed to the grass dividing frame 32, thereby supporting the grass dividing board 21 in front of the grass dividing frame 32. The hitch 125 is fastened and fixed to the rib plate section 122 at two points, one above and one below, by bolts 126 or the like. The rear side of the upper part of the hitch 125 is fixed by welding or the like to the front side of a cylindrical tip forming member 128 that forms the tip of the grass dividing frame 32.

[0082] For the grass dividing unit 50 having the above-mentioned configuration, the cutting height detection device 40 is supported rotatably around the front-rear axis O1 as a rotation axis by the front shaft support part 130A, which is the front shaft support part, and the rear shaft support part 130B, which is the rear shaft support part 130. The front shaft support part 130A is provided on the rear side of the grass dividing board 21, and the rear shaft support part 130B is provided on the support frame 100.

[0083] The front shaft support 130A has a boss 132, which is a front support provided on the rear side of the grass dividing board 21, and a front support shaft 131 provided at the front end of the unit support 44 and supported by the boss 132. The front shaft support 130A has a configuration in which the front support shaft 131 protruding forward from the front surface 44b of the unit support 44 is supported by the boss 132 provided at the lower end of the hitch 125.

[0084] The front support shaft portion 131 is an integral part of the unit support 44, and its axis coincides with the axis line O1. The boss portion 132 is a hollow cylindrical portion with an open rear side, and is fixed to the lower end of the hitch 125 by welding or the like. The front support shaft portion 131 is rotatably supported by the boss portion 132 via a bearing member such as a bush with the front portion inserted into the boss portion 132, and is prevented from coming off the boss portion 132 by a set screw 137 and a lock nut 138. In this way, the front shaft support portion 130A supports the front side of the cutting height detection device 40 with respect to the grass dividing unit 50 so as to be rotatable with the front-rear direction as the rotation axis.

[0085] The rear shaft support portion 130B has a stay 142 which is a rear support portion provided on the support frame 100, and a rear support shaft portion 141 which is provided on the rear end portion of the unit support body 44 and supported by the stay 142. The rear shaft support portion 130B has a configuration in which the rear support shaft portion 141 which protrudes rearward from the rear surface portion 44d of the unit support body 44 is supported by the stay 142 which is provided on the support frame 100 via a support plate 143.

[0086] The rear support shaft 141 is an integral part of the unit support 44, and its axis coincides with the axis line O1, and is arranged coaxially with the front support shaft 131. The support plate 143 is fixed to the left side of the lower part of the front inclined part 113 of the support frame 100 by welding or the like. The stay 142 is a member formed by bending a long and narrow rectangular plate-shaped member into a substantially "L" shape, and is fixed to the support plate 143 at two points, front and rear, by bolts 145 or the like. The stay 142 has the front support surface part 142b facing closely to the rear side of the rear surface part 44d of the unit support 44, and supports the rear support shaft 141 rotatably. In this way, the rear shaft support part 130B supports the rear side of the cutting height detection device 40 rotatably with respect to the grass dividing part 50 on the same axis as the front shaft support part 130A, with the front-rear direction as the rotation axis.

[0087] As described above, the cutting height detection device 40 supports the unit support 44 so that it can rotate around the front-to-rear axis O1 relative to the grass dividing section 50, thereby supporting the sensor unit 45 supported by the unit support 44 so that it can swing left and right.

[0088] The cutting height detection device 40 is elastically positioned at a predetermined neutral position with respect to rotation about an axis in the front-rear direction by a return spring 147 provided on the front shaft support portion 130A. The return spring 147 is a so-called torsion spring, which passes through the front support shaft portion 131 protruding from the boss portion 132 and is engaged with a locking pin 148 above the front support shaft portion 131, extending forward from the front surface portion 44b of the unit support body 44.

[0089] [Mowing height detection device operation] During normal operation by the combine harvester 1, that is, when the machine body is moving forward, the cutting height is controlled based on the cutting height detection value by the cutting height detection device 40 so that the cutting height is maintained at a set value. The cutting height is detected when the rotation position of the grounding body 42 relative to the device body 41 is rearward of the reference position.

[0090] When the machine body moves forward, the ground contact body 42, which slides with its tip in contact with the ground surface G1, rotates rearward from a reference position about the rear rotating shaft 62 relative to the case 51 of the device body 41 due to ground sliding resistance (see arrow C1 in FIG. 6). The ground contact body 42 rotates integrally with the rear rotating shaft 62 about the second axis P2, and the rotation of the rear rotating shaft 62 is transmitted to the intermediate rotating shaft 70 via gears or the like. The rotation of the intermediate rotating shaft 70 is detected by the cutting height sensor 43, and the cutting height is detected based on the amount of rotation of the intermediate rotating shaft 70.

[0091] Furthermore, if a lateral external force acts on height-of-cutting detection device 40, for example when the machine is steered with grounding body 42 on the ground, height-of-cutting detection device 40 will rotate about longitudinal axis O1 by front shaft support portion 130A and rear shaft support portion 130B to escape. When the lateral external force acting on height-of-cutting detection device 40 is eliminated, the biasing structure of return spring 147 and locking pin 148 will return height-of-cutting detection device 40 to a predetermined neutral position.

[0092] [Combine control configuration] The control configuration of the combine harvester 1 will be described with reference to FIG. 8. As shown in FIG. 8, the combine harvester 1 includes a control device 200. The control device 200 controls each part of the combine harvester 1 based on input signals from various sensors and the like included in the combine harvester 1. The control device 200 includes a central processing unit (CPU) as an arithmetic processing device that executes various arithmetic processing and control, storage devices such as a random access memory (RAM) and a read only memory (ROM), input / output devices (input / output circuits) such as an input / output interface for data input / output, and peripheral circuits such as a clock circuit, all connected via a bus or the like. The CPU of the control device 200 performs arithmetic processing according to various programs stored in the ROM or the like.

[0093] 8, the combine harvester 1 has a vehicle speed sensor 201, a target cutting height setting operation unit 202, and a cutting height mode changeover switch 203 in addition to the cutting height sensor 43 of the cutting height detection device 40, which are electrically connected to the input device (input circuit) of the control device 200. The control device 200 receives input signals from these sensors, switches, etc., and generates a control signal based on these signals.

[0094] The control device 200 has, as functional units, an engine control unit 211, a vehicle speed control unit 212, a vehicle speed setting unit 213, a mowing lift control unit 214, and a target mowing height setting unit 215.

[0095] The control device 200 performs the following control as output control of the engine 11 by the engine control unit 211. That is, the engine control unit 211 controls the operation of an actuator (not shown) that changes the engine speed so that the speed of the engine 11 (hereinafter referred to as "engine speed") becomes the set speed set by an engine speed operation member (not shown) that is manually operated.

[0096] The engine speed operation member is, for example, an operating member such as an accelerator dial, and is provided in the driving unit 14. An actuator for changing the engine speed is, for example, a fuel injection device provided in the engine 11. The fuel injection device is configured to include a fuel supply pump that draws fuel from a fuel tank, a common rail that stores the fuel pumped from the fuel supply pump in an accumulated state, and a plurality of injectors that inject the accumulated fuel in the common rail into each cylinder of the engine 11.

[0097] The vehicle speed sensor 201 is a sensor that detects the vehicle speed, which is the traveling speed of the combine 1 (traveling body 4). The control device 200 receives an input of a detection signal from the vehicle speed sensor 201 and detects the vehicle speed. The control device 200 controls the vehicle speed by a vehicle speed control unit 212 based on the detection signal from the vehicle speed sensor 201.

[0098] The combine harvester 1 has a traveling HST for changing the traveling speed as the driving unit 220 related to the vehicle speed. Here, the "HST" is a hydraulic stepless transmission that employs a system in which hydraulic pressure generated by driving a hydraulic pump is converted again into rotational force by a hydraulic motor. The HST has a variable displacement pump and motor that are fluidly connected to each other, solenoid valves corresponding to the pump and motor, respectively, and an output shaft. In the HST, the pump is adjusted and driven (traveling drive adjustment) via the solenoid valve for the pump while receiving power from the engine 11, and the drive of the motor by the adjustment drive is transmitted to the output shaft.

[0099] The output shaft of the HST for traveling is interlocked with a transmission mechanism for transmitting driving force to the left and right crawler units 3, 3 that constitute the traveling unit 2. This transmission mechanism is configured including a planetary gear group and has left and right output shafts that transmit driving force to the drive sprockets 3b of the left and right crawler units 3.

[0100] The control device 200 receives a detection signal regarding the forward / rearward rotation operation position (operation amount) of the main shift lever 17, generates control information based on the detection signal, and controls the drive of the drive unit 220 based on the generated control information. The operation amount of the main shift lever 17 is detected by, for example, a rotary encoder or a rotary potentiometer. The control device 200 controls the drive of the pump and motor by controlling the solenoid valve for the HST, and controls the power transmission from the output shaft to the transmission mechanism.

[0101] In such a configuration, the vehicle speed sensor 201 detects, as the vehicle speed, for example, the rotation speed of the crawler unit 3 or the rotation speed of the output shaft of the HST used for traveling. The control device 200 controls the drive unit 220 via the vehicle speed control unit 212 so that the vehicle speed detected by the vehicle speed sensor 201 corresponds to the speed corresponding to the manual operation of the main shift lever 17, etc.

[0102] The vehicle speed setting unit 213 has a set speed and the like previously set and stored for use in controlling the vehicle speed by the vehicle speed control unit 212. Note that the set speed may be set by providing a vehicle speed setting operation unit such as a switch or dial in the driving unit 14 and allowing the setting to be performed by an operator seated in the driver's seat 16.

[0103] The control device 200 controls the lifting and lowering of the reaping unit 5 by operating the reaping lifting cylinder 18 so that the mowing height is maintained at the target mowing height value based on the detection signal from the mowing height sensor 43 through the reaping lifting control unit 214. The control device 200 controls the extension and contraction operation of the reaping lifting cylinder 18 by controlling the operation of the solenoid valve 221 for hydraulic control of the reaping lifting cylinder 18.

[0104] The mowing height target value used for controlling the elevation of the mowing unit 5 by the mowing lifting control unit 214 is set and stored in the mowing height target setting unit 215. The setting of the mowing height target value in the mowing height target setting unit 215 is performed by the mowing height target value setting operation unit 202.

[0105] The target mowing height setting operation unit 202 is provided around the driver's seat 16 in the driver's unit 14, and is operated by an operator seated in the driver's seat 16. The target mowing height setting operation unit 202 is composed of operating devices such as switches and dials, and is provided as a target mowing height setting switch, a target mowing height setting dial, or the like. The target mowing height is set to a value such as 3 cm or 5 cm.

[0106] The control device 200 has, as control modes for the height of the reaping unit 5, a normal mode and a lodging mode in which the mowing height target value is smaller than that in the normal mode. The lodging mode is a mode used when the crop to be reaped is in a lodged state (lodged crop) due to the crop variety, growth conditions, etc., and the lodged crop is reaped at a lower mowing height than in the normal mode. Therefore, when the control mode for the height of the reaping unit 5 is the lodging mode, the mowing height target value used by the reaping lift control unit 214 to control the elevation of the reaping unit 5 becomes smaller than that in the normal mode.

[0107] Switching between the normal mode and the lying mode is performed by operating a cutting height mode changeover switch 203, which serves as a cutting height mode changeover operation unit. The cutting height mode changeover switch 203 is provided around the driver's seat 16 in the driver's section 14, and is operated by an operator seated in the driver's seat 16.

[0108] By way of example only, the target mowing height in normal mode is a value within a range of 2 to 5 cm, and the target mowing height in lodging mode is a value within a range of 0 to 1 cm. The target mowing height is set by operating the target mowing height setting operation unit 202 in each of the normal mode and the lodging mode.

[0109] Specifically, for example, assume that the target mowing height setting operation unit 202 is configured to allow the target mowing height value to be set in 1 cm intervals. In this case, if the above-mentioned numerical ranges for the target mowing height value in each mode are adopted, for example, in normal mode, the target mowing height value can be set to any of 2 cm, 3 cm, 4 cm, and 5 cm by operating the target mowing height setting operation unit 202, and in lodging mode, the target mowing height value can be set to any of 0 cm and 1 cm by operating the target mowing height setting operation unit 202.

[0110] Furthermore, as a mode of recognizing the control mode for the height of the cutting unit 5 in the control device 200, switching between the normal mode and the lowering mode may be performed based on the instruction value of the target cutting height value by operating the target cutting height setting operation unit 202. Specifically, for example, assume that the target cutting height value can be set to N cm (N: integer) at 1 cm intervals within a range of 0 to 5 cm by operating the target cutting height setting operation unit 202. In this case, when the target cutting height value set by operating the target cutting height setting operation unit 202 is set to any of 2 cm, 3 cm, 4 cm, and 5 cm, the normal mode is maintained, and when the set value is set to any of 0 cm and 1 cm, the lowering mode is activated.

[0111] [Mowing lift / vehicle speed control] In the combine harvester 1 having the above-mentioned configuration, the control device 200 controls the elevation of the cutting unit 5, i.e., the control of the cutting height and the control of the vehicle speed in association with each other (hereinafter referred to as "cutting lift / lower and vehicle speed control"). The cutting lift / lower and vehicle speed control will be explained. In the explanation of the cutting lift / lower and vehicle speed control, for the sake of convenience, the cutting height target value for the control of the cutting height is referred to as "cutting height target value R0" and the set speed for the control of the vehicle speed is referred to as "set speed V0".

[0112] With regard to vehicle speed control, the mowing lift / vehicle speed control takes priority over vehicle speed control according to manual operation such as operation of the main speed change lever 17. In other words, according to the mowing lift / vehicle speed control, control is performed to automatically change the vehicle speed in relation to the mowing height control without operation of the main speed change lever 17 or the like.

[0113] In the cutting lifting / vehicle speed control, when the cutting height detected by the cutting height detection device 40 exceeds the cutting height target value R0 or is below the cutting height target value R0, the control device 200 controls the height of the cutting unit 5 so that the cutting height detected by the cutting height detection device 40 becomes the cutting height target value R0, and also reduces the vehicle speed of the traveling body 4.

[0114] That is, in conjunction with the control of the cutting height by the cutting lift control section 214 based on the cutting height target value R0, which is based on the detection signal from the cutting height sensor 43, the control device 200 controls the vehicle speed by the vehicle speed control section 212 to decelerate the vehicle speed when the cutting height value detected by the cutting height detection device 40 (hereinafter referred to as the "cutting height detection value R1") deviates from the cutting height target value R0. The cutting height target value R0 is preset and stored in a storage device such as a ROM in the control device 200.

[0115] Specifically, when the mowing height detection value R1 is smaller than the target mowing height value R0, the control device 200 raises the mowing unit 5 and decelerates the vehicle speed in order to set the mowing height to the target mowing height value R0. Similarly, when the mowing height detection value R1 is greater than the target mowing height value R0, the control device 200 lowers the mowing unit 5 and decelerates the vehicle speed in order to set the mowing height to the target mowing height value R0.

[0116] Then, after the control device 200 decelerates the vehicle speed, the cutting height detection value R1 becomes the cutting height target value R0, and the vehicle speed control unit 212 controls the vehicle speed to return to the speed before deceleration, that is, the speed corresponding to manual operation such as operation of the main shift lever 17.

[0117] As described above, in this embodiment, the following control is performed as a control method for the combine harvester 1 that detects the cutting height and controls the height of the cutting unit 5 so that the detected cutting height (cutting height detection value R1) becomes the preset cutting height target value R0. That is, when the cutting height detection value R1 is above the cutting height target value R0 or below the cutting height target value R0, the height of the cutting unit 5 is controlled so that the detected cutting height becomes the cutting height target value R0, and the vehicle speed is also decelerated.

[0118] By performing such control, the vehicle speed is decelerated as the cutting unit 5 ascends and descends, so that it is possible to suppress the cutting unit 5 from leaving grass uncut due to the cutting unit 5 ascending and descending, and from plunging into the ground G1. Here, plunging of the cutting unit 5 refers to the grass dividing board 21, etc. provided at the front of the cutting unit 5 plunging into the ground G1, which may cause culm stubble to come out of the ground G1, or cause soil or crops to become clogged in the cutting blade device 24 of the cutting unit 5, etc., reducing work efficiency. Therefore, by suppressing the plunging of the cutting unit 5, it is possible to improve work efficiency.

[0119] The leaving of stalks by the cutting unit 5 is likely to occur due to insufficient lifting of the stalks by the lifting device 22 when the cutting unit 5 is raised. For this reason, by slowing down the vehicle speed as the cutting unit 5 is raised, the lifting effect of the lifting device 22 of the stalks can be improved, and the leaving of stalks can be suppressed. Even if the leaving of stalks occurs, the distance over which the leaving of stalks occurs can be shortened.

[0120] Furthermore, the cutting unit 5 is likely to crash into the ground when it descends. For this reason, by slowing down the vehicle speed as the cutting unit 5 descends, the cutting unit 5 can be prevented from crashing into the ground. That is, by slowing down the vehicle speed, it is possible to buy time to raise the cutting unit 5 before it crashes into the ground G1, and therefore it is possible to prevent the cutting unit 5 from crashing into the ground. Furthermore, by slowing down the vehicle speed, even if the cutting unit 5 crashes into the ground G1, it is possible to keep the degree of the crash small (shorten the distance of the crash), and it is possible to reduce the impact of the cutting unit 5 crashing into the ground G1 on the work.

[0121] The reaping lifting / vehicle speed control is used, for example, in reaping work of lodging crops. In reaping work of lodging crops, the target mowing height value R0 is set lower than normal in order to ensure that the raising device 22 lifts up the stalks. In this embodiment, there are two control modes for the height of the reaping unit 5: a normal mode and a lodging mode in which the target mowing height value R0 is lower than that in the normal mode, and the reaping lifting / vehicle speed control is executed in the lodging mode.

[0122] That is, on condition that the control mode for the height of the cutting unit 5 is the lowering mode, the control device 200 controls the height of the cutting unit 5 so that the cutting height detected by the cutting height detection device 40 becomes the cutting height target value R0, and also reduces the vehicle speed. In this manner, the cutting lifting / vehicle speed control is performed in a state in which the lowering mode is selected by operating the cutting height mode changeover switch 203. Note that, as described above, the lowering mode can also be initiated by operating the cutting height target value setting operation unit 202.

[0123] In this way, by performing the cutting lifting / vehicle speed control in a state where the cutting height target value R0 is set relatively low for cutting work on fallen crops, i.e., in the falling mode, it is possible to effectively prevent uncut crops and the cutting unit 5 from crashing into the crop, which are likely to occur when cutting fallen crops. Also, in cutting work in normal mode, such as when cutting crops that are not fallen, if the vehicle speed is reduced every time the cutting unit 5 rises or falls, it is considered that the work efficiency will decrease. Therefore, by performing the cutting lifting / vehicle speed control only in the falling mode, it is possible to prevent the work efficiency in normal mode from decreasing.

[0124] In the normal mode, the cutting height target value R0 is larger than in the lodging mode, so there is a low possibility that the cutting unit 5 will crash into the culm, and since the position of the culm tips is high, there is a low possibility that the fallen culms will be left uncut due to the lifting and lowering of the cutting unit 5. Therefore, in the normal mode, good workability can be obtained without prioritizing workability and reducing the vehicle speed.

[0125] An example of a control mode by the control device 200 will be described with reference to the flowchart shown in Fig. 9. Fig. 9 is a flowchart showing a first control mode by the control device 200. The control described below is performed by the CPU of the control device 200 reading and executing a predetermined control program stored in a storage device such as a RAM.

[0126] 9, first, it is determined whether the control mode for the height of the mowing unit 5 is the lowering mode (S10). In this step, it is determined whether the mode is the lowering mode based on the mode selected by the mowing height mode switch 203 or the command value of the target mowing height value set by the target mowing height setting operation unit 202.

[0127] In step S10, if it is not determined that the mode is the lowering mode (S10, NO), the mowing lifting / vehicle speed control is not performed. In this case, the control mode for the height of the mowing unit 5 is the normal mode, and the vehicle speed deceleration control accompanying the raising and lowering of the mowing unit 5 is not performed. When performing the mowing lifting / vehicle speed control, the control device 200 constantly determines whether the control mode for the height of the mowing unit 5 is the lowering mode or not.

[0128] On the other hand, if it is determined in step S10 that the mode is the lowering mode (S10, YES), the mowing lifting / vehicle speed control is performed. That is, first, it is determined whether or not either of the two conditions is met: that the mowing height detection value R1 is greater than the mowing height target value R0, or that the mowing height detection value R1 is less than the mowing height target value R0 (S20).

[0129] If it is determined in step S20 that neither of the above two conditions is met (S20, NO), the vehicle speed is not reduced, that is, the vehicle speed according to the manual operation of the main shift lever 17, etc. is maintained, and the process returns to step S10. On the other hand, if it is determined in step S20 that either of the above two conditions is met (S20, YES), the vehicle speed is reduced (S30).

[0130] That is, when the mowing height detection value R1 is greater than the mowing height target value R0, the mowing unit 5 is controlled to move down and the vehicle speed is decelerated, and when the mowing height detection value R1 is less than the mowing height target value R0, the mowing unit 5 is controlled to move up and the vehicle speed is decelerated. After the vehicle speed is decelerated, the mowing height detection value R1 becomes the mowing height target value R0, and the vehicle speed is returned to the speed before deceleration, such as the speed corresponding to the operating position of the main shift lever 17.

[0131] According to the above-described mowing lifting / lowering and vehicle speed control, the vehicle speed is automatically decelerated in accordance with the lifting / lowering state of the mowing unit 5 in the lowering mode, so that the vehicle speed can be reduced at an earlier timing than when, for example, an operator manually decelerates the vehicle speed in response to the lifting / lowering operation of the mowing unit 5, and delays in the timing of deceleration of the vehicle speed can be prevented. Delays in the timing of deceleration of the vehicle speed can cause the mowing unit 5 to leave grass uncut or to crash into something. Therefore, according to the control content according to this embodiment, it is possible to reduce the burden on the operator while suppressing the mowing unit 5 from leaving grass uncut or to crash into something.

[0132] In addition, in the mowing lifting / vehicle speed control, the following control is performed as an example of a control mode for decelerating the vehicle speed: That is, the control device 200 decelerates the vehicle speed when the mowing height detection value R1 exceeds a value obtained by adding a predetermined value to the mowing height target value R0 or falls below a value obtained by subtracting a predetermined value from the mowing height target value R0.

[0133] When the predetermined value for the upward movement of the mowing unit 5 is set to a first predetermined value ΔRa and the predetermined value for the downward movement of the mowing unit 5 is set to a second predetermined value ΔRb, the control device 200 reduces the vehicle speed on the condition that the mowing height detection value R1 exceeds the value obtained by adding the first predetermined value ΔRa to the mowing height target value R0 or the mowing height detection value R1 falls below the value obtained by subtracting the second predetermined value ΔRb from the mowing height target value R0. The first predetermined value ΔRa and the second predetermined value ΔRb are set and stored in advance in a storage device such as a ROM in the control device 200.

[0134] In other words, in the mowing lift / vehicle speed control, the mowing height target value R0, which is compared with the mowing height detection value R1, is set as a numerical range having a width of the mowing height target value R0 ± a predetermined value with respect to the control for decelerating the vehicle speed. This numerical range has (mowing height target value R0 - second predetermined value ΔRb) as the lower limit value (hereinafter referred to as "lower limit value (R0 - ΔRb)") and (mowing height target value R0 + first predetermined value ΔRa) as the upper limit value (hereinafter referred to as "upper limit value (R0 + ΔRa)"). In other words, the control device 200 decelerates the vehicle speed when the mowing height detection value R1 exceeds the upper limit value (R0 + ΔRa), and decelerates the vehicle speed when the mowing height detection value R1 falls below the lower limit value (R0 - ΔRb).

[0135] Therefore, the relationship between the range of the mowing height detection value R1 and the control contents corresponding to each range is as follows. When the mowing height detection value R1 is below the lower limit (R0-ΔRb), the mowing unit 5 is controlled to rise and the vehicle speed is decelerated. When the mowing height detection value R1 is in the range from the lower limit (R0-ΔRb) to the mowing height target value R0, only the mowing unit 5 is controlled to rise. When the mowing height detection value R1 is in the range from the mowing height target value R0 to the upper limit (R0+ΔRa), only the mowing unit 5 is controlled to fall. When the mowing height detection value R1 is above the upper limit (R0+ΔRa), the mowing unit 5 is controlled to fall and the vehicle speed is decelerated.

[0136] The first predetermined value ΔRa and the second predetermined value ΔRb may be the same or different. The first predetermined value ΔRa and the second predetermined value ΔRb are set to, for example, 20 mm. In this case, when the first predetermined value ΔRa and the second predetermined value ΔRb are the same, the value of the mowing height detection value R1 exceeds the range of the mowing height target value R0 ±20 mm, and the vehicle speed is decelerated.

[0137] An example of a control mode by the control device 200 will be described with reference to the flowchart shown in Fig. 10. Fig. 10 is a flowchart showing a second control mode by the control device 200. Note that descriptions that overlap with the first control mode described above will be omitted as appropriate.

[0138] As shown in FIG. 10, first, it is determined whether the control mode for the height of the reaping unit 5 is the lowering mode or not (S110).

[0139] If it is not determined in step S110 that the mode is the lodging mode (S110, NO), no mowing lifting / vehicle speed control is performed. On the other hand, if it is determined in step S110 that the mode is the lodging mode (S110, YES), it is determined whether or not either of the two conditions is met: that the mowing height detection value R1 is above the upper limit value (R0+ΔRa) or that the mowing height detection value R1 is below the lower limit value (R0-ΔRb) (S120).

[0140] In step S120, if it is determined that neither of the above two conditions is met (S120, NO), the vehicle speed is not decelerated and the process returns to step S110. On the other hand, in step S120, if it is determined that either of the above two conditions is met (S120, YES), the vehicle speed is decelerated (S130).

[0141] In the series of controls described with reference to FIG. 10, the lifting and lowering control of the cutting unit 5 based on the target cutting height value R0 based on the detected cutting height value R1 is performed together with the control related to the deceleration of the vehicle speed.

[0142] As described above, a numerical range is set with the target cutting height value R0 as a reference value for controlling the vehicle speed, and the value of the detected cutting height value R1 until the vehicle speed is decelerated is controlled to have a range with respect to the target cutting height value R0. According to this type of control, in addition to the effects obtained by the first control mode, it is possible to decelerate the vehicle speed only when the lifting range of the cutting unit 5 is relatively large, so that it is possible to suppress the cutting unit 5 from leaving grass uncut and the cutting unit 5 from crashing into other areas, and it is also possible to prevent hunting when the lifting range of the cutting unit 5 is relatively small.

[0143] With regard to steps S30 and S130 of the flowcharts shown in Figures 9 and 10, as an example of a control mode when decelerating the vehicle speed, control is performed such that the degree of deceleration of the vehicle speed increases as the amount of ascent and descent of the cutting unit 5 increases.

[0144] That is, the control device 200 increases the degree of vehicle speed deceleration the greater the amount by which the mowing height detection value R1 exceeds the mowing height target value R0, and increases the degree of vehicle speed deceleration the greater the amount by which the mowing height detection value R1 falls below the mowing height target value R0. The amount by which the mowing height detection value R1 exceeds the mowing height target value R0 is set as the "amount of increase T1," and the amount by which the mowing height detection value R1 falls below the mowing height target value R0 is set as the "amount of decrease T2."

[0145] Regarding vehicle speed deceleration control, when an upper limit value (R0+ΔRa) and a lower limit value (R0-ΔRb) are used for comparison with the cutting height detection value R1 as described above, the greater the amount by which the cutting height detection value R1 exceeds the upper limit value (R0+ΔRa), the greater the degree of deceleration of the vehicle speed, and the greater the amount by which the cutting height detection value R1 falls below the lower limit value (R0-ΔRb), the greater the degree of deceleration of the vehicle speed.

[0146] In the deceleration control of the vehicle speed, the "degree of deceleration" is a concept including the deceleration (negative acceleration) and the deceleration rate. Increasing the degree of deceleration as the increase amount T1 and the decrease amount T2 are larger includes, for example, the following control aspects.

[0147] First, there is a control mode in which the deceleration is gradually increased in accordance with an increase in the amount of rise T1 and the amount of fall T2. In this control mode, for example, the deceleration is increased in proportion to the increase in the amount of rise T1 and the amount of fall T2.

[0148] In addition, there is a control mode in which the deceleration rate with respect to the vehicle speed at that time is changed in accordance with the increase in the ascending amount T1 and the descending amount T2. In this control mode, specifically, for example, the following control is performed.

[0149] The values ​​of the rise amount T1 and the fall amount T2 are divided into a plurality of ranges by a predetermined numerical range (for example, 10 mm) according to the increase amount, and a deceleration rate corresponding to each range is set in advance. If these ranges are set as a first range, a second range, and a third range in order from the smallest value to the largest value for the rise amount T1 and the fall amount T2, respectively, coefficients (N1, N2, N3) related to the deceleration rate corresponding to each range are set in advance and stored in the vehicle speed control unit 212 or the like.

[0150] For example, the coefficient N1 corresponding to the first range is set to 0.9, the coefficient N2 corresponding to the second range is set to 0.7, and the coefficient N3 corresponding to the third range is set to 0.5, etc. In this case, if the vehicle speed at the timing of decelerating is speed V (m / s), in the first range where the ascending amount T1 and descending amount T2 are relatively small, the speed V (m / s) is decelerated to 0.9·V (m / s) (to 90% of the speed). In the second range where the ascending amount T1 and descending amount T2 are medium, the speed V (m / s) is decelerated to 0.7·V (m / s) (to 70% of the speed). In the third range where the ascending amount T1 and descending amount T2 are relatively large, the speed V (m / s) is decelerated to 0.5·V (m / s) (to 50% of the speed).

[0151] In this way, the deceleration rate according to this control mode corresponds to the reduction rate of the coefficient multiplied by the speed V (m / s), and the smaller the value of this coefficient, the greater the degree of deceleration due to the deceleration rate. Note that the vehicle speed during mowing work is, for example, about 1 to 2 (m / s).

[0152] In this way, the greater the amount of rise T1 and the amount of fall T2, the greater the degree of deceleration of the vehicle speed, thereby making it possible to suppress the cutting unit 5 from leaving grass uncut or from running into something. In other words, the greater the amount of rise T1 and the amount of fall T2, the greater the possibility that the cutting unit 5 will leave grass uncut or from running into something, so by increasing the deceleration rate of the vehicle speed in response to such a situation, it is possible to effectively suppress the cutting unit 5 from leaving grass uncut or from running into something.

[0153] As an example of a control mode for decelerating the vehicle speed, a predetermined set speed V0 is set in advance, and when the vehicle speed detected by the vehicle speed sensor 201 exceeds the set speed V0, control is performed to decelerate the vehicle speed to the set speed V0.

[0154] That is, when the vehicle speed when lowering or raising the cutting unit 5 exceeds a preset set speed V0, the control device 200 decelerates the vehicle speed so that the vehicle speed becomes the set speed V0. The set speed V0 is preset and stored in a storage device such as a ROM in the control device 200.

[0155] In the vehicle speed deceleration control, the set speed V0 is set as the target value of the vehicle speed, and the vehicle speed is decelerated so that the vehicle speed detected by the vehicle speed sensor 201 (hereinafter referred to as the "detected vehicle speed V1") becomes the set speed V0. In other words, in the vehicle speed deceleration control, the set speed V0 becomes the lower limit of the vehicle speed. Therefore, if the detected vehicle speed V1 is equal to or lower than the set speed V0, the vehicle speed is not decelerated.

[0156] The set speed V0 is set to a speed that is sufficiently slower than the vehicle speed during mowing work. Specifically, and by way of example only, the set speed V0 is approximately 0.5 (m / s).

[0157] In such a deceleration control of the vehicle speed with the set speed V0 as a target value, the degree of deceleration may be increased as the amount of increase T1 and the amount of decrease T2 as described above increase. In this case, the set speed V0 may be set to a value that increases the degree of deceleration according to the amount of elevation of the cutting unit 5, for example. do In the control, the speed is set to be slower than the vehicle speed at the most decelerated state relative to the general vehicle speed during mowing work.

[0158] In this way, by controlling the vehicle speed to be decelerated with the set speed V0 as the target value, the vehicle speed in the decelerated state can be reliably set to a low vehicle speed, and it is possible to prevent the mowing unit 5 from leaving any grass uncut or from running into anything. In other words, if the vehicle speed in the decelerated state is not sufficiently slow, there is a high possibility that the mowing unit 5 will leave any grass uncut or from running into anything, so by decelerating the vehicle speed to the set speed V0 in response to such a situation, it is possible to effectively prevent any grass being left uncut or from running into anything.

[0159] As an example of a control mode when the vehicle speed is decelerated using the set speed V0, control is performed such that the degree of deceleration of the vehicle speed increases as the difference between the detected vehicle speed V1 and the set speed V0 increases.

[0160] That is, the control device 200 increases the degree of deceleration of the vehicle speed as the difference between the vehicle speed (detected vehicle speed V1) when lowering or raising the cutting unit 5 and the set speed V0 increases. The difference between the detected vehicle speed V1 and the set speed V0 is defined as the "speed difference ΔV."

[0161] In the deceleration control of the vehicle speed, the degree of deceleration increases as the speed difference ΔV increases, for example, in the following control manner.

[0162] First, there is a control mode in which the deceleration is gradually increased as the speed difference ΔV increases. In this control mode, for example, the deceleration is increased in proportion to the value of the speed difference ΔV.

[0163] In addition, there is a control mode in which the deceleration rate with respect to the vehicle speed at that time is changed as the speed difference ΔV increases. Specifically, in this control mode, the following control is performed, for example.

[0164] The value of the speed difference ΔV is divided into a plurality of ranges by a predetermined numerical range, and a deceleration rate corresponding to each range is set in advance. If these ranges are set as a first range, a second range, and a third range in order from the smallest value of the speed difference ΔV to the largest value, coefficients (N1, N2, N3) related to the deceleration rate corresponding to each range are set in advance and stored in the vehicle speed control unit 212 or the like.

[0165] For example, the coefficient N1 corresponding to the first range is set to 0.9, the coefficient N2 corresponding to the second range is set to 0.7, the coefficient N3 corresponding to the third range is set to 0.5, etc. In this case, if the vehicle speed at the timing of decelerating is speed V (m / s), in the first range where the speed difference ΔV is relatively small, the speed V (m / s) is decelerated to 0.9·V (m / s) (to 90% of the speed). In the second range where the speed difference ΔV is medium, the speed V (m / s) is decelerated to 0.7·V (m / s) (to 70% of the speed). In the third range where the speed difference ΔV is relatively large, the speed V (m / s) is decelerated to 0.5·V (m / s) (to 50% of the speed).

[0166] In this way, by increasing the degree of deceleration of the vehicle speed as the speed difference ΔV increases, it is possible to prevent the mowing unit 5 from leaving grass uncut or from running into something. In other words, a large speed difference ΔV means that the detected vehicle speed V1 is fast, and the faster the detected vehicle speed V1, the higher the possibility of the mowing unit 5 leaving grass uncut or from running into something. Therefore, by increasing the degree of deceleration of the vehicle speed in response to such a situation, it is possible to effectively prevent the mowing unit 5 from leaving grass uncut or from running into something.

[0167] An example of a control mode using the set speed V0 by the control device 200 will be described with reference to the flowchart shown in Fig. 11. Fig. 11 is a flowchart showing a third control mode by the control device 200. Note that descriptions that overlap with the first and second control modes described above will be omitted as appropriate.

[0168] As shown in FIG. 11, first, a determination is made as to whether the control mode for the height of the cutting unit 5 is the lowering mode or not (S210). If it is not determined to be the lowering mode (S210, NO), no cutting lifting / vehicle speed control is performed. If it is determined to be the lowering mode (S210, YES), step S220, which is similar to step S120 shown in FIG. 10, is performed.

[0169] If it is determined in step S220 that neither of the two conditions is met (S220, NO), the vehicle speed is not decelerated and the process returns to step S210. On the other hand, if it is determined in step S220 that either of the above two conditions is met (S220, YES), it is determined whether the detected vehicle speed V1 is higher than the set speed V0 (S230).

[0170] In step S230, if it is not determined that the detected vehicle speed V1 is higher than the set speed V0 (S230, NO), the vehicle speed is not decelerated. On the other hand, in step S230, if it is determined that the detected vehicle speed V1 is higher than the set speed V0 (S230, YES), the vehicle speed is decelerated (S240).

[0171] In the vehicle speed deceleration control in step S240, the vehicle speed is decelerated until the detected vehicle speed V1 becomes the set speed V0. In step S240, at least one of the following controls is performed: the control to increase the degree of deceleration of the vehicle speed as the increase amount T1 and the decrease amount T2 are larger, and the control to increase the degree of deceleration of the vehicle speed as the speed difference ΔV is larger.

[0172] In the series of controls described with reference to FIG. 11, the lifting and lowering control of the cutting unit 5 based on the target cutting height value R0 based on the detected cutting height value R1 is performed together with the control related to the deceleration of the vehicle speed.

[0173] According to the above-described cutting lifting / lowering and vehicle speed control, the vehicle speed is automatically reduced depending on the lifting / lowering state of the cutting unit 5, thereby reducing the burden on the operator and effectively preventing the cutting unit 5 from leaving any grass uncut or crashing into other land.

[0174] As an example of a control mode when decelerating the vehicle speed, a plurality of set speeds V0 are set according to the amount of increase T1 and the amount of decrease T2, and the set speed V0 is changed so that the set speed V0 becomes lower as the amount of increase T1 and the amount of decrease T2 become larger. That is, in the vehicle speed control using the set speed V0, the set speed V0 is set to become lower as the amount of increase T1 or the amount of decrease T2 becomes larger. In this control mode, specifically, for example, the following control is performed.

[0175] The values ​​of the rise amount T1 and the fall amount T2 are divided into a plurality of ranges by a predetermined numerical range (for example, 10 mm) according to the increase amount, and a set speed V0 corresponding to each range is set in advance. If these ranges are set as a first range, a second range, and a third range in order from the smallest value to the largest value for the rise amount T1 and the fall amount T2, respectively, the set speed V0 corresponding to each range is set in advance and stored in the vehicle speed control unit 212 or the like.

[0176] For example, the first set speed V01, which is the set speed V0 corresponding to the first range, is set to 0.7 (m / s), the second set speed V02, which is the set speed V0 corresponding to the second range, is set to 0.5 (m / s), and the third set speed V01, which is the set speed V0 corresponding to the third range, is set to 0.5 (m / s). V03 is set as 0.3 (m / s).

[0177] In this way, by changing the set speed V0 to the deceleration side according to the increase in the amount of ascent T1 and the amount of descent T2, it is possible to prevent the cutting unit 5 from leaving grass uncut or from running into something. In other words, the greater the amount of ascent T1 and the amount of descent T2, the higher the possibility that the cutting unit 5 will leave grass uncut or run into something, so by lowering the set speed V0, which is the lower limit of the vehicle speed at which the vehicle speed is decelerated in response to such a situation, it is possible to effectively prevent the cutting unit 5 from leaving grass uncut or from running into something.

[0178] In the reaping lifting / lowering and vehicle speed control, control may be performed to change the lifting / lowering speed of the reaping unit 5 in accordance with the degree of deceleration of the vehicle speed. Control of the lifting / lowering speed of the reaping unit 5 will be described.

[0179] As an example of a control mode of the lifting and lowering speed of the reaping unit 5, the control is performed such that the lifting speed of the reaping unit 5 is increased as the degree of deceleration of the vehicle speed increases when the vehicle speed is decelerated. That is, the control device 200 increases the lifting speed of the reaping unit 5 as the degree of deceleration of the vehicle speed increases.

[0180] The lifting speed of the reaping unit 5 is adjusted by controlling the extension and retraction speed of the reaping lifting cylinder 18 via a solenoid valve by the control device 200. The extension and retraction speed of the reaping lifting cylinder 18 is adjusted by the supply and discharge amount of hydraulic oil supplied to the reaping lifting cylinder 18 via a solenoid valve controlled by the control device 200.

[0181] The relationship between the degree of deceleration of the vehicle speed and the ascending speed of the mowing unit 5 is not particularly limited. For example, when deceleration is used as the degree of deceleration of the vehicle speed, there is a control mode in which the ascending speed of the mowing unit 5 is gradually increased in accordance with an increase in deceleration that increases as the ascending amount T1 and the descending amount T2 increase. In this control mode, for example, the ascending speed of the mowing unit 5 is increased in proportion to the increase in the deceleration.

[0182] Furthermore, as described above, when a deceleration rate set for each numerical range of the values ​​of the ascent amount T1 and the descent amount T2 is used as the degree of deceleration of the vehicle speed, the lifting speed of the cutting unit 5 corresponding to each numerical range of the values ​​of the ascent amount T1 and the descent amount T2 is set in advance and stored in the cutting lifting control unit 214, etc.

[0183] When the first range, second range, and third range are set as the numerical ranges of the rise amount T1 and the fall amount T2 following the above-mentioned example, a first rise speed corresponding to the first range, a second rise speed corresponding to the second range, and a third rise speed corresponding to the third range are set as the rise speed of the reaping unit 5. Here, the second rise speed is faster than the first rise speed, and the third rise speed is faster than the second rise speed.

[0184] In this way, by making the ascending speed of the cutting unit 5 faster as the vehicle speed decelerates, the cutting unit 5 can be quickly moved upward when the vehicle speed decelerates, thereby effectively preventing the cutting unit 5 from crashing into something.

[0185] In addition, the control may be such that the greater the degree of deceleration of the vehicle speed, the slower the ascending speed of the reaping unit 5. By slowing the ascending speed of the reaping unit 5 as the greater the degree of deceleration of the vehicle speed, the amount of stalks passing under the reaping unit 5 can be reduced, and the amount of stalks left uncut by the reaping unit 5 can be reduced.

[0186] As an example of a control mode of the lifting and lowering speed of the reaping unit 5, the greater the degree of deceleration of the vehicle speed when the vehicle speed is decelerated, the slower the descent speed of the reaping unit 5. That is, the control device 200 slows down the speed at which the reaping unit 5 is lowered, the greater the degree of deceleration of the vehicle speed.

[0187] The relationship between the degree of deceleration of the vehicle speed and the descent speed of the mowing unit 5 is not particularly limited. For example, when deceleration is used as the degree of deceleration of the vehicle speed, there is a control mode in which the descent speed of the mowing unit 5 is gradually slowed down in accordance with an increase in deceleration that increases as the rise amount T1 and the fall amount T2 increase. In this control mode, for example, the descent speed of the mowing unit 5 is reduced in proportion to the increase in deceleration.

[0188] Furthermore, as described above, when a deceleration rate set for each numerical range of the values ​​of the ascent amount T1 and the descent amount T2 is used as the degree of deceleration of the vehicle speed, the descent speed of the cutting unit 5 corresponding to each numerical range of the values ​​of the ascent amount T1 and the descent amount T2 is set in advance and stored in the cutting lifting control unit 214, etc.

[0189] When the first range, second range, and third range are set as the numerical ranges of the lift amount T1 and the lowering amount T2 following the above-mentioned example, a first lowering speed corresponding to the first range, a second lowering speed corresponding to the second range, and a third lowering speed corresponding to the third range are set as the lowering speed of the reaping unit 5. Here, the second lowering speed is slower than the first lowering speed, and the third lowering speed is slower than the second lowering speed.

[0190] In this way, by slowing down the descent speed of the cutting unit 5 as the vehicle speed decelerates, the cutting unit 5 can be lowered with a smoother movement when the vehicle speed decelerates. This shortens the travel distance when the cutting height detection value R1 deviates from the cutting height target value R0, and effectively prevents the cutting unit 5 from crashing into something.

[0191] In addition, the control may be such that the greater the degree of deceleration of the vehicle speed, the faster the descent speed of the reaping unit 5. By making the descent speed of the reaping unit 5 faster as the degree of deceleration of the vehicle speed becomes greater, the amount of stalks passing under the reaping unit 5 can be reduced, and the amount of stalks left uncut by the reaping unit 5 can be reduced.

[0192] The above-described embodiment is an example of the present invention, and the present invention is not limited to the above-described embodiment. Therefore, even if it is not the above-described embodiment, various modifications are possible according to the design, etc., as long as it does not deviate from the technical idea of ​​the present invention. In addition, the effects described in this disclosure are merely examples and are not limited, and other effects may be present. In addition, the configurations and control modes of each of the above-described embodiments can be appropriately combined.

[0193] In the above-described embodiment, the cutting height detection device 40 is provided at the left end of the reaping support machine frame 20 constituting the reaping unit 5, but the location at which the cutting height detection device 40 is provided is not particularly limited. The cutting height detection device 40 may be provided at the right end of the reaping support machine frame 20, for example, by having a configuration symmetrical to that of the above-described embodiment. Furthermore, the cutting height detection device 40 may be provided at multiple locations, for example, by providing it at both the left and right ends of the reaping support machine frame 20.

[0194] Furthermore, in the above-described embodiment, the mowing lifting / vehicle speed control is a control that is executed when the control mode of the mowing unit 5 is the lowering mode, but the mowing lifting / vehicle speed control may also be performed when the control mode of the mowing unit 5 is the normal mode.

[0195] Furthermore, in the above-described embodiment, the control mode for the height of the mowing unit 5 is switched between the normal mode and the lowering mode by operating the mowing height mode changeover switch 203 or based on the setting value of the target mowing height value set by the target mowing height setting operation unit 202. In this regard, a configuration may be adopted in which the control mode for the height of the mowing unit 5 is automatically switched using a detection device such as a camera or a sensor.

[0196] Specifically, when a camera is used to switch the control mode, a camera 204 for switching the control mode is connected to the control device 200, as shown in Fig. 8. The camera 204 is, for example, a CCD camera, and is connected to the control device 200 via a connection cable or the like.

[0197] The camera 204 is provided, for example, at a predetermined location in the cabin 13 or the reaping unit 5, and captures an image of the uncut stalks in a predetermined range in the field in front of the reaping unit 5 during reaping work. The image signal obtained by the camera 204 is input to the control device 200. The control device 200 performs predetermined signal processing based on the image signal from the camera 204 to determine whether the uncut stalks are in a fallen state, and if it determines that the stalks are in a fallen state, switches the control mode of the height of the reaping unit 5 to a falling mode.

[0198] In addition, when a sensor is used to switch the control mode, a stalk height sensor 205 for switching the control mode is connected to the control device 200 as shown in Fig. 8. The stalk height sensor 205 is, for example, an ultrasonic sensor that uses ultrasonic waves of a frequency that shows a characteristic reflection from grains, and is connected to the control device 200 via a connection cable or the like.

[0199] The culm height sensor 205 is provided, for example, at a predetermined location in the cabin 13 or the reaping unit 5, and detects the vegetation height of the uncut culms by emitting ultrasonic waves toward the uncut culms in a predetermined range in front of the reaping unit 5 in the field during reaping work and receiving the reflected waves. A detection signal regarding the height of the culms obtained by the culm height sensor 205 is input to the control device 200. The control device 200 determines whether the uncut culms are in a lodging state based on the detection signal from the culm height sensor 205, and if it determines that they are in a lodging state, switches the height control mode of the reaping unit 5 to a lodging mode. [Explanation of symbols]

[0200] 1. Combine Harvester 4 Running body 5 Reaping part 14 Driving Department 18 Mowing lift cylinder 40 Cutting height detection device 43 Cutting height sensor 200 Control device R0 Cutting height target value R1 Cutting height detection value T1 increase T2 descending amount V0 setting speed V1 Detected vehicle speed ΔRa First Predetermined Value ΔRb Second Predetermined Value ΔV Speed ​​difference

Claims

1. A combine harvester comprising: a cutting unit that is provided so as to be raised and lowered relative to a traveling body; a cutting height detection device for detecting a cutting height, which is the height of the cutting unit; and a control device for controlling the height of the cutting unit so that the cutting height detected by the cutting height detection device becomes a preset target value, When the cutting height detected by the cutting height detection device is above the target value or below the target value, the control device controls the height of the cutting unit so that the cutting height detected by the cutting height detection device becomes the target value, and reduces the vehicle speed of the traveling machine body. A combine harvester characterized by the above.

2. The control device includes: The control mode for the height of the reaping unit includes a normal mode and a falling mode in which the magnitude of the target value is smaller than that of the normal mode, On the condition that the control mode is the lowering mode, the height of the cutting unit is controlled so that the cutting height detected by the cutting height detection device becomes the target value, and the vehicle speed of the traveling machine body is reduced. The combine harvester according to claim 1 .

3. The control device reduces the vehicle speed when the cutting height detected by the cutting height detection device exceeds a value obtained by adding a predetermined value to the target value or falls below a value obtained by subtracting a predetermined value from the target value. The combine harvester according to claim 1 or 2.

4. The control device increases a degree of deceleration of the vehicle speed as the amount by which the cutting height detected by the cutting height detection device exceeds the target value or falls below the target value increases. The combine harvester according to any one of claims 1 to 3.

5. When the vehicle speed when the cutting unit is lowered or raised exceeds a preset speed, the control device reduces the vehicle speed so that the vehicle speed becomes the preset speed. The combine harvester according to any one of claims 1 to 4.

6. The control device increases a degree of deceleration of the vehicle speed as a difference between the vehicle speed and the set speed increases when the cutting unit is lowered or raised. The combine harvester according to claim 5 .

7. The set speed is set to be lower as the amount by which the cutting height detected by the cutting height detection device exceeds the target value or falls below the target value increases. The combine harvester according to claim 5 or 6.

8. The control device increases the speed at which the reaping unit is raised as the vehicle speed decreases. The combine harvester according to any one of claims 4 to 7.

9. The control device reduces the speed at which the cutting unit is lowered as the degree of deceleration of the vehicle speed increases. The combine harvester according to any one of claims 4 to 8.

10. A method for controlling a combine harvester, comprising: a cutting unit that is provided so as to be raised and lowered relative to a traveling body; detecting a cutting height that is the height of the cutting unit; and controlling the height of the cutting unit so that the detected cutting height becomes a preset target value, When the detected cutting height is higher than the target value or is lower than the target value, the height of the cutting unit is controlled so that the detected cutting height becomes the target value, and the vehicle speed is reduced. A method for controlling a combine harvester.

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