JP2020174537A - Work vehicle - Google Patents

Abstract

To provide a work vehicle capable of properly adjusting a vehicle speed regardless of whether a driver is a beginner or an expert of driving, performing efficiently, work travel without hindrance, and facilitating adjustment operation of a vehicle speed properly, when starting the work travel.SOLUTION: A vehicle speed control device comprises: automatic control which actuates an actuator 67 so that a vehicle speed reaches a control target speed which is set artificially, when a predetermined automatic condition is established, and when the vehicle speed once reaches the control target speed, if a work load is deviated from a proper range, actuates the actuator 67 so as to reduce the vehicle speed until the work load becomes in the proper range.SELECTED DRAWING: Figure 6

Description

The present invention relates to a work vehicle mainly for agriculture such as a combine harvester, a tractor, or a passenger-type rice transplanter. Specifically, a shift lever provided in a control unit and an actuator of a vehicle speed control device are linked to a traveling transmission to perform these shift operations. The present invention relates to a work vehicle in which the vehicle speed is manually or automatically controlled by means.

Agricultural work vehicles perform various operations such as cultivating or leveling fields, planting or sowing seedlings in the prepared fields, or harvesting the planted and sown crops. When the work vehicle performs these operations while traveling by itself, it is possible to shorten the work time and improve the work efficiency by increasing the traveling speed (vehicle speed) as much as possible.

Therefore, the work speed is increased and the work efficiency is improved by increasing the size of the work vehicle. However, even if the work vehicle is enlarged, there is a limit to the output of the engine that is the power source to be mounted on each work vehicle, and a work vehicle with work capacity and running performance is balanced with the maximum output of this engine. Will be provided.

Therefore, even when working with a high-performance work vehicle, if the vehicle speed is increased unnecessarily and the work is carried out, the load on the work part and the load on the running part increase, and the engine becomes overloaded and overheats. Or cause an engine stall. In addition, if a processed product exceeding its capacity is supplied to the working part or an overload is applied, the harvested crops may be lost or clogged, or the working part may be damaged. Rather, it takes time to restore these and the work efficiency is greatly improved. To reduce.

Therefore, when carrying out work running, it is necessary to carry out work running in a state where the engine has a certain margin and in an appropriate range that does not exceed the limit of the capacity of the working unit. Skilled workers who have worked for many years are familiar with such circumstances from experience, and these skilled workers are familiar with, for example, a decrease in engine speed, engine noise, or work unit in actual work. It is possible to adjust the vehicle speed to an appropriate level by capturing the load noise generated by the engine.

However, inexperienced beginners have a problem that they do not know how to adjust the vehicle speed properly and work at a low speed to reduce work efficiency, or conversely, work at a high speed to cause an engine stall. Therefore, beginners will receive advice from experts, and if the vehicle speed is adjusted to the speed heard from the experts in this way, the work can be done efficiently without any trouble like the experts. it can.

However, the appropriate working speed always fluctuates depending on the soil quality of the field, the dry and wet conditions, the material conditions to be harvested, etc., so at the vehicle speed that actually received the advice, the work running will be overloaded and will not stall or stall. However, the work is carried out under a high load condition, which may cause crop loss.

Therefore, as a technology that is effective in solving such a problem, for example, there is a disadvantage that the load on the engine exceeds the target load and causes an engine stall, the work is interrupted, and the work efficiency is lowered. Load detection means so as not to exceed the set upper limit vehicle speed for the purpose of increasing the vehicle speed and performing work efficiently within the range where the engine load does not exceed the target load while preventing it from occurring. It is known to provide a vehicle speed control device for shifting and operating a traveling stepless speed changer with an electric motor so that the engine load detected by the engine is maintained at the target load (see Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 10-108529 Japanese Unexamined Patent Publication No. 10-115367

As described above, in order for even a beginner to work efficiently without any trouble like an expert, it is desirable to adjust the vehicle speed appropriately and perform the work running. In addition, the worker needs to turn or turn at the headland in order to complete the work run of one stroke and perform the work run of the next stroke. In this case, the traveling transmission may be accelerated or decelerated manually. Or, since it is moved backward once, it is necessary to return to the appropriate vehicle speed used in the previous stroke and resume the work running when the next stroke is reached.

Then, in order to return to the proper vehicle speed each time the work run of one stroke is started, for example, it is necessary to remember the operation position of the shift lever and return it to the original operation position accurately, which is a troublesome operation. However, there is a problem that an appropriate vehicle speed cannot be obtained immediately due to an erroneous operation. In addition, beginners lack the ability to adapt to changes in fields and material conditions, so it is confirmed that the vehicle speed is not necessarily the appropriate vehicle speed just by observing the vehicle speed for which advice was given. There is a possibility that the work is actually performed in an overloaded state or a high load state.

Therefore, as described in the prior art document, a vehicle speed control device is provided so that the load on the engine does not become excessive and causes an engine stall, so that the work is not interrupted and the work efficiency is lowered. By automatically decelerating the vehicle speed, even a beginner can work efficiently at an appropriate vehicle speed without any trouble while avoiding an overload state or a high load state of the engine.

However, in the prior art literature, the engine load (ST-X) defined by the amount of decrease of the engine speed X from the reference speed ST in the no-load state of the engine, which is preset and stored, is a preset target. The transmission electric motor is driven so as to be maintained at the load (target down amount), and is driven only on the deceleration side in the deceleration operation mode, and the upper limit vehicle speed is not exceeded in the acceleration / deceleration operation mode. It is driven by the speed-up side and the deceleration side, respectively.

Therefore, the vehicle speed when the work vehicle is working will fluctuate depending on the setting of the reference rotation speed ST and the target load (target down amount) in the no-load state of the engine, and the vehicle speed heard by the beginner from the expert. There is a problem that it cannot be adjusted. Further, in the deceleration operation mode, the vehicle can be driven only on the deceleration side, but the prior art document does not describe how to set the vehicle speed before deceleration.

Therefore, if this is performed by manually operating the speed change lever, it will be troublesome to return the speed change lever to the original operation position when starting the work running. In the prior art document, in the acceleration / deceleration operation mode, the upper limit of the vehicle speed is set so as not to exceed the upper limit vehicle speed, so that the speed does not exceed the upper limit against the intention of the operator.

However, in this case, only two upper limits are set, automatic acceleration / deceleration (low) and automatic acceleration / deceleration (high). Therefore, depending on the setting of the reference speed ST or the target load in the no-load state of the engine. Even if the initial vehicle speed can be set to high or low when performing work driving, it must be possible to set the vehicle speed more finely in order to perform work driving efficiently without any trouble. After all, the technology of the prior art document cannot be adopted as it is.

Therefore, in view of the above problems, the present invention can appropriately adjust the vehicle speed regardless of whether the vehicle is a beginner or an expert, and can efficiently perform the work without any trouble, and it is troublesome to start the work. An object of the present invention is to provide a work vehicle capable of easily performing an appropriate vehicle speed adjustment operation.

In the work vehicle of the present invention, firstly, in order to solve the above problems, a shift lever provided in the control unit and an actuator of the vehicle speed control device are linked to the traveling transmission, and the vehicle speed is manually or automatically controlled by these shift operation means. In a vehicle, when a predetermined automatic condition is satisfied, the vehicle speed control device operates an actuator so that the vehicle speed reaches an artificially set control target speed, and the vehicle speed once reaches the control target speed. After that, when the work load deviates from the proper range, the actuator is provided with automatic control to operate the actuator so as to reduce the vehicle speed until the work load falls within the proper range.

Secondly, the present invention is characterized in that the vehicle speed control device operates an actuator so as to gradually reduce the vehicle speed by a predetermined amount when the workload deviates from an appropriate range. Further, the present invention is thirdly characterized in that the vehicle speed control device determines an appropriate range of the work load based on the load of the engine and the load of the work unit.

Fourth, in the present invention, when the vehicle speed control device manually operates the speed change lever while the automatic control is being executed and the vehicle speed is increased by a predetermined amount exceeding the control target speed, the vehicle speed is increased. Is characterized by performing upper limit control for decelerating the actuator so as not to exceed the control target speed by a predetermined amount. Fifth, the present invention is characterized in that the vehicle speed control device includes, in the automatic condition, a condition that satisfies the condition at the start of the work running of one stroke and does not satisfy the condition after the end.

Moreover, in the sixth aspect of the present invention, the vehicle speed control device does not substantially perform automatic control when the vehicle speed falls below the control start speed by manually operating the shift lever while executing the automatic control. However, after that, when the speed change lever is manually operated to increase the vehicle speed above the control start speed, the automatic control is restarted and the actuator is operated so that the vehicle speed reaches the artificially set control target speed. To do.

According to the work vehicle of the present invention, in a work vehicle in which a shift lever provided in a control unit and an actuator of a vehicle speed control device are linked to a traveling transmission and the vehicle speed is manually or automatically controlled by these shift operation means, the vehicle speed control is performed. When the predetermined automatic conditions are satisfied, the device operates the actuator so that the vehicle speed reaches the artificially set control target value, and once the vehicle speed reaches the control target speed, the workload is within the appropriate range. It is equipped with an automatic control that operates the actuator to reduce the vehicle speed until the workload falls within the appropriate range when the vehicle deviates from the above range.

Therefore, the worker can set the vehicle speed at which the work running can be performed efficiently and stably before the start of the work running as the control target speed based on the empirical rule and the advice. Further, when the work running is actually started, the vehicle speed control device operates the actuator so that the vehicle speed reaches the artificially set control target speed when the predetermined automatic conditions are satisfied. Therefore, the vehicle speed is started at the beginning of the work running. Can be automatically adjusted to the proper vehicle speed.

Further, since the vehicle speed control device operates the actuator so as to reduce the vehicle speed until the work load enters the appropriate range when the work load deviates from the appropriate range after the vehicle speed reaches the control target speed once. Even if the vehicle speed set as the control target speed is not always appropriate, the work running can be performed efficiently without any trouble while eliminating the overload and high load states.

The vehicle speed control device is used when the work load is small and there is room for speeding up after the vehicle speed reaches the control target speed or after the work load enters the appropriate range and deceleration is completed. Even if there is, the speed is not automatically increased, and the operator can safely carry out the work by eliminating the unintended speed increase. Further, this can prevent frequent acceleration / deceleration of the vehicle speed, and can improve the work accuracy under a stable vehicle speed.

Further, in the present invention, the vehicle speed control device operates an actuator so as to gradually reduce the vehicle speed by a predetermined amount when the work load deviates from an appropriate range. Then, by using a predetermined amount of vehicle speed at this time, for example, a deceleration value per time that can be expected to eliminate the load, the traveling time in a high load state can be reduced as much as possible. Then, even if the vehicle speed is decelerated only once, if it does not fall within the appropriate range, the vehicle speed is further decelerated step by step by a predetermined amount, so that the vehicle speed can be decelerated without excess or deficiency and stable work running can be performed.

Further, in the present invention, the vehicle speed control device determines an appropriate range of the work load based on the load of the engine and the load of the work unit. Then, when a high load or an overload is applied to the engine or the working part, the vehicle speed is reduced to maintain the load of the engine or the working part within an appropriate range. Therefore, it is possible to eliminate overheating and engine stall of the engine, eliminate troubles such as loss and clogging of harvested crops, and damage to the working part, and prevent deterioration of work efficiency and work accuracy.

Then, in the present invention, when the vehicle speed control device manually operates the shift lever while the vehicle speed control device is executing the automatic control and the vehicle speed is increased by a predetermined amount exceeding the control target speed, the vehicle speed becomes the control target. Upper limit control is performed to decelerate the actuator so that the speed does not exceed a predetermined amount. If the upper limit control is set while the automatic control is being executed in this way, the operator determines that there is a margin in the work load, or the vehicle speed automatically decelerated due to the local load in the field is the original vehicle speed. If you want to return to, you can increase the vehicle speed by manually operating the shift lever.

However, in this case, if the vehicle speed is erroneously increased too much by manual operation, the workload increases thereafter and the risk of engine stall increases. Therefore, the vehicle speed of the vehicle speed control device increases by exceeding the control target speed by a predetermined amount. If it is determined that the speed has been increased, the vehicle speed is returned to the control target speed plus a predetermined amount to reduce the risk of high-load driving. Therefore, the vehicle speed control device gives priority to the manual operation of the operator, but when it is judged that the stable work running may be hindered by this manual operation, the vehicle speed control is performed by limiting the manual operation. It can be stabilized.

Further, in the present invention, the vehicle speed control device includes, in the automatic condition, a condition that satisfies the condition at the start of the work running of one stroke and does not satisfy the condition after the end. In this way, the automatic control is always terminated after the end of one stroke due to the condition that the automatic condition is not satisfied after the end of the work run of one stroke. Therefore, when the automatic condition is satisfied again at the start of the work run of the next process, the vehicle speed control device operates the actuator so as to reach the control target speed artificially set, and automatically controls the vehicle speed to return to the control target speed.

Therefore, the vehicle speed changed by the traveling speed change lever manually operated when turning or turning on the headland in order to complete the work traveling of one stroke and to perform the work traveling of the next stroke is restarted by the above-mentioned automatic control. Since the control target speed can be automatically returned to the control target speed, the work running can be resumed based on the set vehicle speed without requiring any special operation. Further, since the vehicle speed decelerated due to the high load in the previous stroke is reset once, the work running can be performed efficiently without taking over the decrease in efficiency due to the deceleration of the vehicle speed.

Moreover, in the present invention, the vehicle speed control device does not substantially perform automatic control when the vehicle speed falls below the control start speed by manually operating the speed change lever while executing the automatic control, provided that the vehicle speed control device does not perform automatic control thereafter. When the speed change lever is manually operated to increase the vehicle speed above the control start speed, the automatic control is restarted and the actuator is operated so that the vehicle speed reaches the artificially set control target speed.

In this way, for example, the automatic control of the vehicle speed is restarted by the manual operation of the speed change lever without being turned on by a switch or the like, and the actuator is operated so that the vehicle speed reaches the artificially set control target speed. be able to. Therefore, the operability can be improved, and the vehicle speed increase in this case is different from the speed increase not intended by the operator, and the vehicle speed is increased to the control target value based on the intention of the operator to increase the speed. It is possible to ensure safety.

It is a side view of the combine (working vehicle) to which this invention is applied. It is a top view of the combine. It is a top view of the control part. It is a schematic power transmission diagram of a combine. It is a perspective view of the shifting operation means linked with the traveling transmission. It is a block diagram of a vehicle speed control device. It is a flowchart of vehicle speed automatic control. It is a vehicle speed setting table. It is a substitute photograph of the liquid crystal monitor screen which shows the warning example of a workload.

An embodiment of the present invention will be described based on a combine that constitutes an agricultural work vehicle. As shown in FIGS. 1 and 2, the combine harvester that threshes rice and wheat while harvesting is composed of a 6-row harvesting self-removing combine 1 and runs below the body frame (running machine) 2 that is framed in a substantially rectangular shape. Left and right crawler traveling devices 4 are provided via the frame 3. The left and right crawler traveling devices 4 include a drive sprocket 6 attached to a drive shaft protruding from the left and right of the transmission case 5, an idle wheel 7 pivotally supported by the traveling frame 3, a track roller 8, and rubber wound around them. A crawler 9 is provided.

Further, a substantially rectangular driving frame is integrally connected to the front right side of the airframe 2 in the forward direction of the airframe, and a control unit 10 is provided over the operating frame and the airframe 2 behind the operating frame 2. As shown in FIG. 3, the control unit 10 is provided with a driver's seat 12 behind the floor 11, and a front console (front operation panel) 13 is provided at the front of the floor 11 of the floor 11 and the driver's seat 12. A side console (side operation panel) 14 is provided on the left side, and a cabin 15 covers the control unit 10.

Further, the cutting portion 16 is provided so as to be able to move up and down from the left front portion of the machine body frame 2 to the front portion of the control portion 10 by a hydraulic cylinder (not shown). Then, the cutting section 16 divides the standing hair culms in the field into cut grain culms and uncut grain culms by seven weed bodies 17 provided at the lower part of the front end and narrow guides 18 on the left and right, and becomes the outermost on the left and right. The harvested culm that entered between the weeds 17 is raised by a pulling device 19 provided with a raising claw 19a, and then, as shown in FIG. 4, a scraping device 22 composed of a scraping belt 20 with protrusions and a star wheel 21. While gathering together, the culm near the root of the stock is cut by the reciprocal cutting blade device 23.

Further, the grain culms cut and cut by the cutting blade device 23 are sent backward by the star wheel 21 of the scraping device 22, and the grain culms sent backward are provided on the left, right, and center of the stock transfer device 24. It is taken over by 25 and 26 and transported further backward. The terminal portion of the stock source transport device 26 provided in the center faces the merging portion provided in the middle of the transport path of the right stock source transport device 24, and the grain culm transported by the middle stock source transport device 26 faces the merging portion in the middle. In, the culm is merged with the grain culm transported by the right stock transfer device 24, and thereafter, the right stock transfer device 24 takes over.

On the other hand, the terminal portion of the stock source transport device 25 provided on the left side faces the terminal portion of the right stock source transfer device 24, and the grain culms transported by the left stock source transfer device 25 have been transported by the right stock source transfer device 24. It merges with the grain culm at the confluence at the end of both transport devices 24 and 25. Further, the merged grain culms are taken over by the handling depth transport device 27 whose starting end portion faces the two confluence portions, and are further conveyed rearward and upward.

Then, the grain culm handed over to the handling depth transport device 27 is handed over to the threshing food chain 29 from the terminal portion of the handling depth transport device 27 via the auxiliary transport device 28. Although the transport route on the stock root side of the grain culm has been mainly described so far, the tip side of the grain culm is provided on the upper side of the right stock root transport device 24, the handling depth transport device 27, and the auxiliary transport device 28. Locked to the tip transfer device 30, the transfer claws attached to the transfer chains of the left suction transfer device 31 and the middle suction transfer device 32 provided on the upper side of the left stock transfer device 25 and the middle stock transfer device 26. Transport.

Further, the threshing section 33 is provided on the left side of the machine frame 2 behind the cutting section 16, and the first and second handling chambers are provided below the cylinder cover 34 that covers the upper part. Among them, in the first handling chamber, a threshing feed chain 29 and its holding rail 35 for transporting the culm transported from the cutting section 16 along the handling port, a first handling cylinder provided with handling teeth and its receiving net. Etc. are provided. In addition, the second handling chamber is attached to the first handling chamber so as to face the rear of the machine from the rear end tip side of the first handling barrel, and the straw waste mixed with grains that could not be threshed in the first handling chamber. A second handling cylinder for processing and the like and a receiving net thereof are provided.

On the other hand, a sorting chamber is provided below the first and second handling chambers. The sorting chamber is provided with a swinging flow plate, a first spiral and a second spiral, a wall insert fan, a suction fan, etc., and grains and the like leaking from the receiving net of the handling chamber are placed on the swinging flow plate. The sorted grains are transferred from the 1st spiral to the grain tank 37 via the grain raising device 36, and the 2nd product mixed with straw debris is oscillated from the 2nd spiral through the 2nd reducing device. Put it back on the board.

Further, the straw debris reaching the end of the rocking flow plate, the straw debris captured by the suction fan, or the straw debris discharged from the end of the second handling cylinder is discharged to the outside of the machine behind the threshing section 33. Further, the culm discharged from the handling chamber after the threshing process is completed is conveyed toward the disc type cutter 39 by the straw discharge transport device 38, and the disc type cutter 39 is further conveyed by the straw discharge transport device 38. Shred the culm that has come and release it as cut straw to the site where it was cut, or release it as long straw as it is.

Then, the grain tank 37 is provided further behind the driving part composed of the diesel engine 40 and the like provided from below the control part 10 to the rear, and temporarily stores the grains transferred by the grain raising device 36. When the grain tank 37 is full of grains, the discharge auger 41 is operated to discharge the grains from the grain tank 37 and discharge the grains to a container or the like outside the machine.

The discharge auger 41 includes a vertical pipe containing a horizontal spiral and a vertical spiral provided at the bottom of the grain tank 37, and the vertical pipe is rotatably erected behind the grain tank 37 by an auger swivel motor. It is composed of a vertical pipe 42 and a second vertical pipe 45 which can be raised and lowered by a hydraulic cylinder 44 via a gear case 43 above the first vertical pipe 42.

Next, the above-mentioned cutting section 16 will be further described. As shown in FIGS. 1 and 4, the cutting section 16 rotatably supports the rear side of the cutting section 16 on the upper portion of the support column provided near the left front portion of the machine frame 2. A transmission frame 46 is provided, which is composed of a pipe case connected in a substantially E-shape in which the front side is moved up and down by a hydraulic cylinder. Further, a preprocessing frame 47, a support frame, and the like are attached to the front portion of the transmission frame 46.

Further, the transmission frame 46, the pretreatment frame 47, the support frame, and the like include a pulling device 19, a scraping device 22, a cutting blade device 23, a stock source transfer device 24, 25, 26, and a handling depth transfer device 27. Each device such as the auxiliary transfer device 28, the tip transfer device 30, and the suction transfer devices 31 and 32, the weed body 17, the side cover 48, the tip guide plate 49, the hood 50, and the like are attached.

A transmission shaft provided with a bevel gear is pivotally supported in the transmission frame 46, and the engine 40 provided in the prime mover is via a cutting clutch 52 composed of a transport HST (hydrostatic continuously variable transmission) 51 and a belt tension clutch. The input shaft 53 of the input transmission unit 46a in the transmission frame 46 is driven, and then the vertical transmission unit 46b, the tip / auxiliary transport transmission unit 46c, the right stock transmission unit 46d, the handling depth transmission unit 46e, and the middle stock transmission unit 46e. Each device is driven from the transmission unit 46f, the lower transmission unit 46g, the left stock transmission unit 46h, the raising transmission unit 46i, and the cutting blade drive unit 46j.

The threshing section 33 is driven from the engine 40 via a threshing clutch 54 composed of a belt tension clutch, and the transfer HST 51 is driven by the power branched from the drive system of the threshing section 33, and the threshing section 33 is threshed from the transfer HST 51. It drives each part of the threshing field chain 29 and the cutting part 16 of the part 33. Further, the traveling transmission that drives the left and right crawler traveling devices 4 is driven from the engine 40 via a traveling clutch 55 composed of a belt tension clutch.

Further, the traveling transmission includes a traveling HST (hydrostatic continuously variable transmission) 56 constituting the main transmission attached to the transmission case 5, a standard (cutting and degreasing work speed) provided in the transmission case 5, and traveling (running on the road). It is equipped with an auxiliary transmission composed of a gear transmission 57 capable of switching to (speed), and further, the left and right drive sprockets 6 are driven via a steering device composed of left and right side clutches, brakes, etc. provided in the transmission case 5. ..

Therefore, when traveling on the road, the engine 40 is started by the starter key, the auxiliary shift lever 58 provided in the control unit 10 is operated to the forward travel position, and the main shift lever 59 is moved from the neutral position to the forward forward position. Alternatively, the combine 1 can be driven at a required speed by positioning the combine harvester in the backward position and increasing or decreasing the position. Further, when the cutting work is performed in the field, the combine 1 can be driven at a speed lower than the road speed by operating the auxiliary shift lever 58 to the rear standard position and similarly increasing or decreasing the main shift lever 59.

When performing the cutting work, the front side of the power clutch switch 60 configured by the momentary type rocker switch provided in the control unit 10 is pushed, and the grain removal clutch 54 is first engaged by a power clutch electric motor (not shown). The front side of the power clutch switch 60 is pushed again to engage the cutting clutch 52 by the power clutch electric motor to drive each part of the grain removal section 33 and the cutting section 16 and the cutter 39. When disengaging the cutting clutch 52 and the threshing clutch 54, the clutches can be disengaged in sequence by pressing the power clutch switch 60 toward the rear.

Further, when the multi-steering lever (elevating operation tool) 61 provided on the control unit 10 is tilted forward from the neutral position, the cutting unit 16 can be lowered from the raised non-working posture to the lowered working posture. .. Then, when the multi-steering lever 61 is returned to its neutral position, the lowering of the cutting portion 16 is stopped, and when the multi-steering lever 61 is tilted rearward from the neutral position, the cutting portion 16 can be raised.

Further, when the multi-steering lever 61 is tilted from its neutral position to the left-right direction, a steering device composed of left-right side clutches, brakes, etc. provided in the transmission case 5 can be operated to change the traveling direction of the combine 1. it can. When the cutting work of the culm of the field is started under such an operation, the transport HST51 is configured to increase or decrease its output rotation speed in synchronization with the traveling speed (vehicle speed), whereby the output rotation speed of the field is increased or decreased. The fluffy culm can be raised to an appropriate standing posture, and the culm can be stably transported to the threshing section 33.

The outline of the combine has been described above, but the vehicle speed control device that automatically controls the running speed when the work running is performed next will be described. First, the main shifting lever (shifting lever) 59 provided in the control unit 10 described above includes an arm plate 59a provided at the base as shown in FIG. 5, and a lever rod 59b rotatably attached to the upper portion of the arm plate 59a. It is composed of a grip 59c attached to the upper part of the lever rod 59b. Then, the arm plate 59a is pivotally supported on the rotating shaft 63 fixed to the console frame 62 of the side console 14 so as to be rotatable back and forth.

Further, the lower part of the arm plate 59a and the servo control lever (not shown) of the traveling HST (traveling transmission) 56 are connected via a ball joint 64 and a rod 65, and the main shifting lever 59 is manually rotated in the front-rear direction. The traveling HST56 is linked so that it can rotate forward (forward), neutralize (stop), reverse (reverse), and accelerate or decelerate the vehicle speed. On the other hand, a motor base 66 is attached to the console frame 62, and the motor base 66 is provided with a vehicle speed transmission motor (actuator) 67 composed of a geared motor and a two-stage reduction gear mechanism 68.

Further, the input gear 68a of the two-stage reduction gear mechanism 68 is attached to the output shaft of the vehicle speed transmission motor 67, while the final output gear 68d of the two-stage reduction gear mechanism 68 is rotatably supported on the rotation shaft 63. Then, a friction plate 69 is interposed between the arm plate 59a and the facing surface of the final output gear 68d, and a disc spring 70, a washer 71, and a double nut 72 are attached to the rotating shaft 63, so that the vehicle speed shifting motor 67 is positive. The arm plate 59a is rotated via the friction plate 69 by the reverse rotation, and the traveling HST 56 is operated in the same manner as in the case of manually operating the main speed change lever 59 so that the vehicle speed can be accelerated or decelerated.

A main shift lever potentiometer 73 with a return spring is attached to the motor base 66, and the tip of the actuating arm fixed to the actuating shaft of the potentiometer 73 is brought into contact with a pin provided on the arm plate 59a to be in front of and behind the main shift lever 59. The operating angle of the direction can be detected. Further, a coil spring 74 is stretched over the lever rod 59b near the base and the arm plate 59a, and the urging force of the coil spring 74 is applied to the neutral position 75a of the lever guide 75 of the main speed change lever 59 provided on the side console 14. The main speed change lever 59 can be held (see FIG. 3).

Therefore, when the main shift lever 59 is operated at any position of the lateral groove (neutral groove) in the left-right direction of the lever guide 75 and then the main shift lever 59 is released, the main shift lever 59 is moved to the neutral position of the lever guide 75. It is held at 75a and can be held so as not to be unexpectedly rotated to the front forward shift region or the rear reverse shift region. Further, when the vehicle speed shift motor 67 is rotated forward and reverse, the main shift lever 59 is rotated in the front-rear direction. However, when the vehicle speed shift motor 67 is rotated forward and reverse, the forward shift region of the lever guide 75 is described later. Since the main shift lever 59 is located only in the case where the main shift lever 59 is located, the main shift lever 59 is not rotated from the lateral groove (neutral groove) to the reverse shift region by the vehicle speed shift motor 67.

The structure in which the speed change lever 59 provided in the control unit 10 and the actuator 67 of the vehicle speed control device are linked to the traveling speed change device 56 has been described above. Next, a method of operating the actuator 67 to control the vehicle speed will be described. As shown in the block diagram shown in the above, the vehicle speed control device mainly consists of three microcomputer units (ECUA, ECUB, E / GECU) 76, 77, 78 and a microcomputer unit (ECUC) for a liquid crystal monitor 79 that warns. Equipped with 80, each unit can communicate with each other via a controller area network (CAN) and share various information.

Among these, the input circuit of the ECU A76 includes a power clutch switch 60 provided in the control unit 10, an engine rotation dial 81, a vehicle speed automatic dial 82, and variable resistors 81a, 82a, 83a and automatic switches of the sorting automatic dial 83, respectively. 81b, 82b, 83b are connected. Then, an engine automatic lamp 81c composed of a light emitting diode, a vehicle speed automatic lamp 82c, and a sorting automatic lamp 83c are connected to the output circuit of the ECU A76.

Further, the main shift lever potentiometer 73, the transmission rotation sensor 84, the transfer rotation sensor 85, the transfer scraping switch 86, the handling depth main switch 87, and the airflow sensor 88 are connected to the input circuit of the ECU B77. Then, the vehicle speed speed change motor 67 is connected to the output circuit of the ECU B77 via the motor relay 89.

Then, in particular, the ECU B77 configured as described above executes automatic vehicle speed control, and the vehicle speed automatically reaches (matches) the artificially set control target speed when a predetermined automatic condition is satisfied. Actuator 67 is operated once, and once the vehicle speed reaches the control target speed, when the work load deviates from the proper range, the actuator 67 is decelerated until the work load enters the proper range. Activate.

Further, when the work load deviates from the appropriate range, the actuator 67 is operated so as to gradually reduce the vehicle speed by a predetermined amount, and the appropriate range of the work load is the load of the engine 40 and the load of the work unit 33. Judge based on. Further, when the speed change lever 59 is manually operated to increase the vehicle speed by a predetermined amount exceeding the control target speed while the automatic control is being executed, the actuator is prevented so that the vehicle speed does not exceed the control target speed by a predetermined amount. The 67 is decelerated (upper limit control).

Then, the condition that satisfies the condition at the start of the work run of one stroke and the condition that does not satisfy the condition after the end is included in the automatic condition, and the vehicle speed is manually operated by manually operating the speed change lever 59 while the vehicle speed automatic control is being executed. However, when the speed is lower than the control start speed, the automatic control is not substantially performed. However, when the speed change lever 59 is manually operated to increase the vehicle speed to the control start speed or higher, the automatic control is restarted and the vehicle speed is artificially adjusted. The actuator 67 is operated so as to reach the control target speed set to.

Hereinafter, the specific control content of the above-mentioned automatic vehicle speed control will be described with reference to the flowchart of FIG. 7. The ECU B77 first presses the vehicle speed automatic dial 82 provided on the control unit 10 to determine whether the vehicle speed automatic switch 82b is turned on. Judgment (S1). Then, when the vehicle speed automatic switch 82b is turned on, the state of the automatic flag F0 to be reset or set is determined in the initial set of the vehicle speed automatic control (S2), and if it is reset, the vehicle speed automatic control is turned on. The automatic flag F0 is set, the setting flag F1 is reset, the 0 value is assigned to the variable k, and the vehicle speed automatic lamp 82c is turned on (S3).

Further, if the automatic flag F0 is set, it is assumed that the vehicle speed automatic control has been turned off, the automatic flag F0 is reset and the vehicle speed automatic lamp 82c is turned off (S4), and the vehicle returns as it is. Further, if the vehicle speed automatic switch 82b is not turned on in step S1, the state of the automatic flag F0 is also determined (S5), and if it is reset, the vehicle speed automatic control is assumed to be turned off and the vehicle returns as it is. However, if it is set, it is assumed that the automatic vehicle speed control is selected, and the success or failure of the automatic condition of the next step is determined (S6).

Here, as automatic conditions for automatic vehicle speed control, the cutting clutch 52 and the grain removal clutch 54 are engaged, the main shift lever 59 is in the forward shift region, the output rotation speed of the transport HST 51 exceeds zero, and the engine rotation speed is a predetermined rotation speed (for example). 2400 rpm) or more, the vehicle speed is the control start speed (control start point: for example 0.3 m / s) or more, the engine rotation automatic control is turned on, the handling depth main switch 87 is ON, and the transport scraping switch 86 is ON. The condition is that all are satisfied.

It should be noted that this information is transmitted to the operation status of the power clutch switch 60, the main speed change lever potentiometer 73, the transfer rotation sensor 85 that detects the output rotation speed of the transfer HST51, the rotation speed of the engine 40 acquired from the E / GECU 78, and the transmission case 5. It can be obtained from the transmission rotation sensor 84 that detects the rotation speed of the transmission shaft on the downstream side of the auxiliary transmission 57 provided. Further, the automatic engine rotation control is turned on depending on the operation status of the automatic switch 81b of the engine rotation dial 81, and the handling depth main switch 87 and the transfer scraping switch 86 are conveyed by the handling depth transfer device 27 and the suction device 22. It is a switch provided as an automatic condition for automatic control of the handling depth by detecting the presence or absence of grain culms.

Further, in the above-mentioned automatic engine rotation control, the engine speed instructing the E / GE ECU 78 that the automatic control is turned on is set, for example, when the cutting clutch 52 or the grain removal clutch 54 is turned on, the discharge auger. When turning or ascending / descending or discharging grains of 41, when the auxiliary transmission 57 is standard, it is 2600 rpm, when the auxiliary transmission 57 is running, it is 2770 rpm, and otherwise it is 1480 rpm, which is idling rotation. The engine speed is controlled so as to reach the indicated speed. If the automatic control is turned off, the engine speed is artificially indicated by the engine speed dial 81 (variable resistor 81a).

Therefore, the automatic condition for the automatic vehicle speed control is, of course, the automatic vehicle speed control that is turned on and off by the operation of the vehicle speed automatic switch 82b (set of the automatic flag F0), and the work unit (the work unit (set of the automatic flag F0)). It is a condition that the cutting section 16, the threshing section 33, etc.) are driven to perform forward running, and the cutting section 16 cuts the fluffy culm to actually perform the work running, and in addition to that. The condition is that the rotation speed of the engine 40 is controlled by the E / GE ECU 78 to a predetermined rotation speed (for example, 2600 rpm).

Then, the ECU B77 resets the setting flag F1 and returns (S7) when turning or turning on the road or on a headland where the automatic conditions described above are not satisfied. However, when the work is actually carried out and the automatic condition is satisfied, the set state of the setting flag F1 is determined (S8), and if the setting flag F1 is reset, the vehicle speed is the control start speed (control start point: for example, 0). .3 m / s) or more is judged (S9), and the operator indicates the intention to carry out the work at the control target speed that artificially sets the vehicle speed, or immediately after the start of the work of one stroke. It is determined whether or not the intention is to perform the work running at a low speed until the cutting height adjustment of the cutting unit 16 becomes stable.

Then, in this case, if the vehicle speed is increased above the control start speed, the current vehicle speed is compared with the artificially set control target speed (control setting point) (S10), and the vehicle speed is lower than the control start speed. A vehicle speed shift motor 67 is rotated forward via a motor relay 89 to increase the vehicle speed, and the vehicle speed automatic lamp 82c is blinked at a low speed (S11). Further, after that, it is determined whether or not the vehicle speed has reached the control target speed (S12), and when the vehicle speed reaches the control target speed, the vehicle speed shift motor 67 is stopped and the vehicle speed automatic lamp 82c is continuously turned on to set. The flag F1 is set (S13).

On the other hand, when the vehicle speed reaches the control target speed, the vehicle speed automatic lamp 82c is continuously turned on and the setting flag F1 is set (S14). When the vehicle speed exceeds the control target speed, the vehicle speed shift motor 67 is reversed to reduce the vehicle speed, and the vehicle speed automatic lamp 82c is blinked at a low speed (S15). Further, after that, it is determined whether or not the vehicle speed has reached the control target speed (S16), and when the vehicle speed reaches the control target speed, the vehicle speed shift motor 67 is stopped and the vehicle speed automatic lamp 82c is continuously turned on to set. The flag F1 is set (S17).

The control target speed used in this case is artificially set by the vehicle speed automatic dial 82 (variable resistor 82a), and the specific control target speed set by the vehicle speed automatic dial 82 is the vehicle speed setting table of FIG. Using the vehicle speed of the control setting point shown together with the control start point of, for example, when the vehicle speed automatic dial 82 is set to "8", the ECU B77 sets the control target speed to V8 m / s. Further, when the vehicle speed reaches the control target speed and the vehicle speed shift motor 67 is stopped, the motor relay 89 includes a short brake circuit, so that the main shift lever 59 is held at the stopped shift position, and the main shift lever 59 is manually operated. The shift position is not changed unless is operated.

Further, if the setting flag F1 is set in step S8, the above-mentioned vehicle speed is not controlled to match the control target speed. Therefore, the vehicle speed is set to the control target speed after the start of work depending on the state of the setting flag F1. The setting flag F1 is used as a flag for determining whether the automatic control has already been performed or has not been performed yet. Then, when the automatic control for setting the vehicle speed to the control target speed has already been performed, the state of the workload is then determined (S18).

In this case, if the workload is overloaded, the deceleration setting speed (deceleration setting point) is the value obtained by incrementing the variable k and subtracting the value obtained by multiplying the predetermined amount Δs by the variable k from the control target speed. (S19), the vehicle speed shift motor 67 is reversed to reduce the vehicle speed, and the vehicle speed automatic lamp 82c is blinked at high speed (S20). Further, it is determined whether the vehicle speed has been reduced to the deceleration set speed (S21), the vehicle speed shift motor 67 is stopped after the vehicle speed has been reduced to the deceleration set speed, and the vehicle speed automatic lamp 82c is continuously blinked (S22). ).

Then, the process returns to step S18 for determining the state of the work load again, and the control for decelerating the vehicle speed by reducing the deceleration set speed by a predetermined amount Δs is repeated until the work load becomes appropriate. The deceleration setting speed used here is, for example, when the vehicle speed automatic dial 82 is set to "8" as shown in the deceleration setting point of the vehicle speed setting table in FIG. 8, the overload is applied from the control setting point. Vd8 m / s is obtained by subtracting a predetermined amount (Δs = 0.3 m / s) that can be expected to be eliminated. If the work load is not eliminated by the first deceleration, the next deceleration set speed will be the speed obtained by subtracting a predetermined amount (Δs = 0.3 m / s) from Vd8 m / s.

Further, the appropriate range of the work load in this case is determined based on the load of the engine 40 and the load of the work part (grain removal part 33). For example, the load of the engine is determined by using a common rail type diesel engine as the engine 40. Therefore, the load factor of the engine that can be obtained from the E / GE ECU 78 is used for the engine rotation speed of 2600 rpm instructed to the E / GE ECU 78. For example, if the load factor of 95% or more continues for 2 seconds or more, it is judged as overload. Therefore, the deceleration control of the vehicle speed described above is performed to prevent overheating and engine stall of the engine 40.

Further, the load of the working unit (threshing unit 33) is leaked from the receiving net in the handling room because the air flow sensor 88 that detects the air volume based on the wind speed in the sorting chamber of the threshing unit 33 detects the air volume very small. It is judged that the load is overloaded based on the condition near the limit of grain selection, in which the dropped grains are remarkably accumulated on the rocking flow plate and the grains are discharged to the outside of the machine together with the straw waste and the like causes grain loss. Then, the deceleration control of the vehicle speed described above is performed to reduce the accumulated amount of the processed material on the rocking flow plate, and appropriate grain selection is performed to prevent grain loss.

When automatic sorting control is performed using the automatic switch 83b of the automatic sorting dial 83 during work, the vehicle speed, the degree of sorting set by the variable resistor 83a of the automatic sorting dial 83, the value of the airflow sensor 88, etc. are integrated. The opening amount of the oscillating fins provided on the oscillating flow plate is automatically adjusted, and the accumulated amount of the processed material on the oscillating flow plate is appropriately controlled to improve the grain sorting accuracy. Therefore, the deceleration control of the vehicle speed is performed when the situation in which the processed material does not decrease even if the swing fin is fully opened continues.

Then, when the above-mentioned workload is appropriate, it is determined whether the vehicle speed exceeds the upper limit set speed (upper limit setting point) obtained by adding a predetermined amount to the control target speed (S23), and the vehicle speed exceeds this speed. If this is the case, the vehicle speed shift motor 67 is reversed to reduce the vehicle speed, and the vehicle speed automatic lamp 82c is blinked at high speed (S24). Further, it is determined whether the vehicle speed has been reduced to the upper limit set speed or less (S25), and when the vehicle speed is reduced to the upper limit set speed or less, the vehicle speed shift motor 67 is stopped and the vehicle speed automatic lamp 82c is continuously blinked (S26). ..

The upper limit setting speed used in this case is, for example, Vu8 m / s when the vehicle speed automatic dial 82 is set to "8" as shown in the upper limit setting point of the vehicle speed setting table in FIG. The predetermined amount to be added to the speed V8 m / s is, for example, 0.2 m / s. Therefore, when the vehicle speed is increased by a predetermined amount exceeding the control target speed by manually operating the main speed change lever 59 during the vehicle speed automatic control, the upper limit control for decelerating the vehicle speed so as not to exceed at least the control target speed by a predetermined amount is performed. This limits the speed of the vehicle from being accidentally increased too much by manual operation.

Further, after the upper limit control, the success or failure of the automatic release condition is determined (S27), and when the automatic release condition is satisfied, the automatic flag F0 is reset, the vehicle speed automatic lamp 82c is turned off, and the vehicle speed automatic control is turned off to return. (S28). The automatic release conditions in this case include the fact that the above-mentioned automatic conditions are not satisfied, including the fact that the vehicle speed automatic control is turned off by the operation of the vehicle speed automatic switch 82b, and the control target set by the vehicle speed automatic dial 82. If any one of the artificially changed speeds is satisfied, the automatic release condition is satisfied, and this control may be performed at any time as an interrupt control when the vehicle speed automatic control is being executed.

Then, when the above-mentioned automatic release condition is not satisfied, it is determined whether the main speed change lever 59 is manually operated and the vehicle speed is lower than the control start speed (0.3 m / s) (S29), and the speed is lower than the control start speed. And reset the setting flag F1 (S30), and then return. Therefore, in this case, when the main speed change lever 59 is manually operated again to increase the vehicle speed to the control start speed (0.3 m / s) or more, the vehicle speed is increased to the control target speed. Control can be resumed.

When the main speed change lever 59 is manually decelerated within a range not lower than the control start speed (0.3 m / s) during automatic vehicle speed control, the above-mentioned control is not performed, so that the operator's intention is Based on this, work can be carried out as it is at low speed. Further, the lower limit speed at which the work running can be performed at a low speed based on the intention of the operator may be higher than the control start speed (0.3 m / s) and may be, for example, 0.5 m / s.

The specific control contents of the automatic vehicle speed control have been described above, but if the control contents are summarized, when the work running is started and the automatic conditions are satisfied, the work running can be performed efficiently first. The vehicle speed is controlled by the control target speed, and the vehicle speed can be automatically adjusted to an appropriate vehicle speed at the beginning of the work running. In addition, once the vehicle speed reaches the control target speed, if the workload deviates from the appropriate range, the vehicle speed is decelerated until the workload falls within the appropriate range, so the artificially set control target speed is not always required. Even if it is not appropriate, it is possible to efficiently carry out work running without hindrance while eliminating overload and high load conditions.

Then, after the vehicle speed reaches the control target speed or after the work load enters the appropriate range and the deceleration is completed, even if the work load is small and there is room for increasing the vehicle speed, it is automatically performed. The speed is not increased to the maximum, and the operator can safely carry out the work by eliminating the unintended speed increase, and the frequent acceleration / deceleration of the vehicle speed can be prevented to improve the work accuracy under a stable vehicle speed. Can be improved.

Further, when the vehicle speed is accelerated or decelerated when the control target speed or the work load deviates from the appropriate range, the description is omitted in the flowchart, but the actuator configured by the vehicle speed shift motor 67 (not limited to the vehicle speed shift motor 67 but hydraulic pressure). The actuator (which may be an actuator such as a cylinder) is not operated continuously but is operated intermittently with a predetermined duty ratio (waste time compensation control in feedback control), so that the vehicle speed is relatively slowly accelerated or decelerated. It is possible to match the vehicle speed with the target speed without excess or deficiency while dealing with safety and delay in response of the workload.

Further, the work load is determined based on the load of the engine and the load of the work part, and the vehicle speed is reduced when any of these loads deviates from the appropriate range. Therefore, overheating and engine stall of the engine 40 are eliminated. , Eliminates troubles such as loss of harvested crops (exhaust of grains from the threshing section 33), clogging of transportation of grain stalks in the cutting section 16 and the threshing section 33, or damage to those working sections, and work efficiency and work accuracy. Can be prevented from decreasing.

The engine load factor and the air volume in the sorting chamber of the threshing unit 33 were used as the work load detection method, but in the case of combine 1 as a work vehicle, the output of the engine 40 is the threshing system, the traveling device system, and the straw processing. It is distributed to the system and the cutting and transporting system, and requires a large amount of required power in this order. For example, it can be judged from the closed circuit pressures of the traveling HST56 as the load of the traveling device system and the transporting HST51 as the load of the cutting and transporting system. The load of the threshing system may be determined by a decrease in the spiral rotation speed of the No. 2 reduction device.

Further, the liquid crystal monitor 79 provided in the control unit 10 may be warned as to which of the above-mentioned systems a high load or an overload is applied (see FIG. 9), and the control target speed in the automatic vehicle speed control is being controlled to increase or decrease. The control state and the stop state, the control target speed, and the like may be displayed on the liquid crystal monitor 79, or the buzzer may be operated together with the vehicle speed automatic lamp 82c to notify the operator.

Then, when the operator determines that there is a margin in the work load during the automatic vehicle speed control, or when he / she wants to return the vehicle speed automatically decelerated due to a local load in the field to the original vehicle speed, the speed change lever is manually operated. When the vehicle speed is increased by the control target speed or the vehicle speed is decelerated by the work load or more to obtain stability, and the vehicle speed is decelerated by the manual operation of the shift lever, the control start speed and the upper limit If the speed is within the set speed range, the vehicle speed can be changed at the will of the operator, so that the degree of freedom in vehicle speed control can be increased.

However, if it is determined that stable work running may be hindered by an erroneous manual operation, the vehicle speed can be automatically decelerated below the upper limit set speed by limiting the manual operation. Further, when the cutting section 16 and the threshing section 33 are continuously driven when turning or turning toward the next step after completing the work run of one step in the field, the cut grain culm is transported to the threshing section 33. When the transport scraping switch 86 and the handling depth main switch 87 are turned off, and the driving of the cutting section 16 and the threshing section 33 is stopped to not transport the cut grain culms, the cutting clutch 52 or the threshing clutch 54 is used. The output rotation speed of the cut-off and transport HST51 becomes zero, and the automatic conditions for automatic vehicle speed control are not satisfied in any case.

Therefore, the vehicle speed control device includes the above-mentioned condition that satisfies the condition at the start of the work run of one stroke and does not satisfy the condition after the end of the work, and the automatic control always ends after the end of one stroke. It will be. Therefore, when the automatic condition is satisfied again at the start of the work run of the next process, the vehicle speed control device operates the actuator so as to reach the control target speed artificially set, and automatically controls the vehicle speed to return to the control target speed.

Therefore, the vehicle speed changed by the main shift lever 59 manually operated when turning or turning on the headland in order to complete the work travel of one stroke and perform the work travel of the next stroke is automatically controlled by the vehicle speed described above. Since it is possible to automatically return to the control target speed by resuming the speed, the work running can be restarted based on the set vehicle speed without requiring any special operation. Further, since the vehicle speed decelerated due to the high load in the previous stroke is reset once, the work running can be performed efficiently without taking over the decrease in efficiency due to the deceleration of the vehicle speed.

At the beginning of the work run in which the vehicle speed is controlled to the control target speed, the work load is not so much applied, but after that, the run is in a state where a steady work load is applied. If an attempt is made to increase the vehicle speed by operating the vehicle speed automatic dial 82, the work load may suddenly increase and an engine stall or the like may be immediately caused. Therefore, when the control target speed is changed by operating the vehicle speed automatic dial 82, the vehicle speed is automatically controlled so as not to be performed in the automatic release condition.

Therefore, if you want to change the control target speed by operating the vehicle speed automatic dial 82, you can interrupt the work running once, then press the vehicle speed automatic dial 82 twice to turn on the vehicle speed automatic control again and restart the work running. , It is possible to automatically control the vehicle speed according to the changed control target speed.

Although the embodiment of the present invention has been described above, the overheating of the engine 40 is mostly caused by the trouble of the cooling water system of the engine in addition to the overload of the work load. In this case, the combine 1 is used as the vehicle speed. The control device is used to automatically control the vehicle speed to zero to stop the running, and further, the cutting clutch 52 or the threshing clutch 54 is automatically disengaged to put the engine 40 in a no-load state to prevent the engine 40 from burning. Can be prevented.

Further, when the grain tank 37 is full of grains, it is necessary to interrupt the work running and discharge the grains to a container or the like installed on the loading platform of a truck that stops near the field. In that case, the grains are discharged near the field. The combine 1 will be moved to the vicinity of the truck that stops on the farm road or the like. However, if the discharge auger 41 is raised during this moving travel to perform a turning operation, there is a risk of falling due to a change in the center of gravity of the aircraft. Therefore, when the vehicle speed control device detects the moving travel, the discharge auger is used. A control device that controls the ascending or turning operation of 41 may be warned to invalidate (prohibit) these operations.

Further, when the discharge auger 41 in which the grains of the grain tank 37 are discharged into a container or the like is stored in the cutting section 16 or the threshing section 33 of the combine 1 in a lying state, the operator operates the traveling transmission 56 to move forward and backward. When the vehicle speed control device detects that the vehicle speed has been performed, it may be automatically controlled so that the vehicle speed becomes zero and the vehicle is stopped. All of these controls are important for ensuring the safety of the operator. It is a matter.

1 combine 10 control unit 16 cutting unit 33 threshing unit 40 engine 56 traveling HST (traveling transmission)
59 Main shift lever (shift lever)
67 Vehicle speed shift motor (actuator)
76, 77, 78 Microcomputer unit (vehicle speed control device)

Claims (6)

In a work vehicle in which a speed change lever provided in the control unit and an actuator of a vehicle speed control device are linked to a traveling speed change device and the vehicle speed is manually or automatically controlled by these speed change operation means, the vehicle speed control device satisfies a predetermined automatic condition. Then, the actuator is operated so that the vehicle speed reaches the control target speed artificially set, and once the vehicle speed reaches the control target speed, when the work load deviates from the appropriate range, the work load is reduced. A work vehicle characterized by being equipped with an automatic control that operates an actuator to reduce the vehicle speed until it falls within an appropriate range. The work vehicle according to claim 1, wherein the vehicle speed control device operates an actuator so as to gradually reduce the vehicle speed by a predetermined amount when the work load deviates from an appropriate range. The work vehicle according to claim 1 or 2, wherein the vehicle speed control device determines an appropriate range of the work load based on the load of the engine and the load of the work unit. In the vehicle speed control device, when the speed change lever is manually operated to increase the vehicle speed by a predetermined amount exceeding the control target speed while the automatic control is being executed, the vehicle speed does not exceed the control target speed by a predetermined amount. The work vehicle according to any one of claims 1 to 3, wherein the upper limit control for decelerating the actuator is performed. The vehicle speed control device according to any one of claims 1 to 4, wherein the automatic condition includes a condition that satisfies the condition at the start of the work running of one stroke and does not satisfy the condition after the end. Work vehicle. The vehicle speed control device does not substantially perform automatic control when the vehicle speed falls below the control start speed by manually operating the shift lever while executing the automatic control, except that the shift lever is manually operated thereafter. The first to fifth aspects of the present invention are characterized in that when the vehicle speed is increased to a speed equal to or higher than the control start speed, the automatic control is restarted and the actuator is operated so that the vehicle speed reaches the artificially set control target speed. The work vehicle described in any one.