JP2516363B2 - Vehicle speed control device for work vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vehicle speed control device for a working vehicle including a continuously variable transmission such as a harvester.

[Prior art]

For example, in a harvester that cuts grain on the field and then performs threshing selection processing, the load on the working units such as the threshing unit and the cutting unit mainly depends on the traveling speed.
In order to improve the work efficiency, it is desirable to adjust the vehicle speed during the harvesting work so that each processing is always performed in the working unit under an appropriate load condition. Therefore, a conventional harvester is provided with a transmission that can continuously change the traveling speed adjustment position, and the lever for changing the traveling speed adjustment position of the transmission is rotated according to the detection result of the current vehicle speed. , Those equipped with a vehicle speed control device that operates so as to match the traveling speed to a set speed that is manually determined by the operator's judgment or automatically determined according to the detection result of the load in the working unit. is there.

[Problems to be solved by the invention]

The conventional vehicle speed control device, when the detection result of the vehicle speed is different from the set speed, rotates the lever a predetermined amount, detects again the vehicle speed that changes according to the rotation, and the detection result is the set speed. It is configured to repeat the predetermined amount of rotation until they match, and when the amount of one rotation is small, when the detection result of the vehicle speed is significantly different from the set speed, it takes a lot of time to realize the set speed. However, if the turning amount of one time is increased to eliminate this difficulty, the detection result of the vehicle speed is slightly smaller (or larger) than the set speed. ), The vehicle speed becomes higher (or lower) than the set speed as a result of the rotation of the lever to the speed-increasing side (or decelerating side) accordingly. On the contrary, to the deceleration side (or speedup side) of the lever Moving is performed, thereafter, increase, deceleration is repeated a plurality of times, there is a drawback that lead to so-called hunting.

Further, such a difficulty similarly occurs in other work vehicles such as a tractor and a rice transplanter equipped with the same vehicle speed control device.

The present invention has been made in view of such circumstances, and when the vehicle speed is different from the set speed, the vehicle speed control device for a working vehicle capable of quickly and surely matching the set speed with the set speed. The purpose is to provide.

[Means for solving problems]

The vehicle speed control device for a working vehicle according to the present invention is mounted on a working vehicle equipped with a transmission capable of steplessly changing its traveling speed adjusting position in accordance with the rotational position of the operating lever. In a vehicle speed control device for a working vehicle that changes a turning position of the lever so as to match a running speed with a set speed, a change speed of the turning position is calculated as a deviation between the running speed and the set speed. Means and means for changing the changing speed of the rotational position based on the calculation result of the means.

[Action]

In the present invention, when the current traveling speed is different from the set speed, the difference between the two is calculated, and when it is large, the operating lever of the transmission is rotated at a high speed, and the deviation is calculated. When is small, the lever is gently rotated.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 is a schematic right side sectional view of a common harvester equipped with a vehicle speed control device for a working vehicle according to the present invention (hereinafter referred to as the device of the present invention), and FIG. 2 is a plan view thereof.

In the figure, 1 is a machine body mounted on the upper side of a pair of left and right traveling crawlers 2, 2 (only one side is shown). On the upper left side of the machine body 1 is a threshing section 3 over the entire length in the front-rear direction, On the right side, the driver's seat DS, the paddy tank 7, and the engine 8 are installed in order from the front, and the aircraft 1
A reaping unit 4 is mounted on the front side of the so as to be able to move up and down according to the forward / backward movement of the hydraulic cylinder 40.

The traveling crawlers 2, 2 are driven simultaneously or separately by the driving force of the engine 8 transmitted via a main clutch (not shown), a hydrostatic continuously variable transmission, and a side clutch. Yes, the aircraft 1 is moved forward, backward, or turned.

Thus, as the harvester moves forward, the grain culm introduced into the mowing section 4 from between the pair of dividers 41, 41 provided on the left and right sides of the front part thereof is located above the mowing section 4, The take-up reel 42 axially supported with the axial direction as the left-right direction of the machine body 1.
While being pulled backward by the rotation of the cutting blade, it is mowed by the cutting blade 43 arranged in the lower part of the mowing section 4, and is laterally supported above the cutting blade 43 with its axial direction being the left-right direction of the machine body 1. By the rotation of the transport auger 44, the feeder house 5 is transported laterally in a state of lying down on the platform 45 on the rear side of the cutting blade 43, and connects the rear side of the reaping section 4 and the upper front side of the threshing section 3. At the front end opening of the feeder house 5
It is inherited by a chain conveyor 50 provided inside, and is conveyed upward and rearward while being sandwiched between the conveyor 50 and the bottom plate of the feeder house 5, and threshed from the rear end opening of the feeder house 5. It is introduced into the handling room 30 of the section 3.

On the bottom plate of the feeder house 5, a plurality of grain culm sensors 51, 51 ... Which detect the presence or absence of grain culm in the feeder house 5, that is, the presence or absence of grain culm fed to the threshing unit 3, are arranged side by side in the left-right direction. is there. As the grain culm sensors 51, 51 ..., for example, the pressure receiving surface of the piezoelectric conversion element is installed toward the inside of the feeder house 5,
When the grain culverts conveyed by the chain conveyor 50 in the feeder house 5 come into contact with these pressure receiving surfaces, one configured to emit a signal of a level according to the pressure receiving from the grain stalks may be used. .

In the handling chamber 30 of the threshing unit 3, a screw handling cylinder having a double pitch screw and a large number of handling teeth projecting from the peripheral surface thereof.
31 is axially supported with its axial length direction aligned with the front-back direction of the machine body 1, and the grain culms introduced into the handling chamber 30 through the rear end opening of the feeder house 5 are Threshing is performed by the action of the handle teeth while being transferred backward by the action of the screw accompanying the rotation. Then, the grated product after the threshing process passes through the receiving net 33 stretched on the lower side of the handling cylinder 31, and on the rocking sorting device 34 arranged below the receiving net 33. And the swinging motion of the device 34, and the Karato device arranged at the lowermost front side of the threshing unit 3.
The specific gravity is selected by a synergistic action with the selection wind blown by 35 and blown as shown by the white arrow in FIG.
That is, the fine grains in the grated product drop onto the No. 1 gutter 35 provided at the upstream side of the sorting air, and the No. 1 gutter.
It is conveyed in the right direction inside 35, and then is conveyed upward in the inside of the fried grain cylinder 35a which is connected to the right end of the inside, and the paddy tank 7
Sent to. In addition, the second product such as the cutting grain and the branch adhering grain in the grated product fell on the second gutter 36 provided on the downstream side of the sorting wind, and the second gutter 36 No. 2 reduction cylinder 36a, which is transported to the right inside and is then connected to the right end of it
Is transported to the upper front in the inside of the container, is re-introduced into the frontmost part of the handling room 30, and is threshed again. Further, the third product such as straw waste contained in the above-mentioned grated food is discharged from the rear end of the screw handling barrel 31 together with the straw discharged from the third mouth 37 opening downward at the rear part of the threshing part 3. It is discharged on the field.

Now, the harvester that performs the threshing and selection processing as described above travels on the field surface at a traveling speed according to the gear ratio set by the continuously variable transmission. A gear shift lever 60 for setting this gear ratio is arranged in the operation column 6 on the left side of the driver's seat DS, and an operator seated in the driver's seat DS rotates the gear to set the gear ratio. Can be set freely. Further, a shift motor 16 for rotating the lever 60 and a shift sensor 15 using a potentiometer for outputting an electric potential according to the rotational position of the lever 60 are provided at the base end pivot portion of the shift lever 60. (See FIG. 3) is mounted, the gear ratio can be changed by the rotation of the conversion lever 60 accompanying the forward rotation or the reverse rotation of the shift motor 16, and the shift sensor 15
It is possible to recognize the current gear ratio based on the detection result of. In addition to the shift lever 60, the operation column 6 includes an automatic switch 11 (see FIG. 3) for instructing the device of the present invention to start its operation, and a vehicle speed setting lever for setting a limit vehicle speed Sx described later. A large number of levers and switches such as 61 are provided.

FIG. 3 is a block diagram showing the configuration of the device of the present invention equipped in the ordinary harvester having the above-described configuration. 10 is a vehicle speed control unit and 20 is an engine speed control unit. The engine speed control unit 20 moves, for example, a fuel rack (hereinafter referred to as a rack) of a fuel injection pump in order to match the speed of the engine 8 with a preset speed (for example, a rated speed of the engine 8). The so-called isochronous control for controlling the amount of fuel supplied to the engine 8 is performed, and the rack position sensor 21 that uses, for example, a differential transformer coaxially mounted on the rack is provided on the input side thereof. , And an engine rotation sensor 22 using, for example, a rotary encoder mounted on the output shaft of the engine 8.
Are connected to each other, and as described later, the vehicle speed control unit
10 output port b ₆ is given a operation command signal from,
Further, the outputs thereof are connected to a rack actuator 23 that drives the rack, for example, using a linear solenoid, and an input port a ₇ of a vehicle speed control unit 10, which will be described later.

The engine speed control unit 20, based on the stored arithmetic expression, from the detected rotation speed input from the engine rotation sensor 22, the target at which the rack should be positioned in order to match this with the set rotation speed. The rack position is calculated, then this is compared with the current rack position input from the rack position sensor 21, and based on the comparison result, the rack actuator 23 for eliminating the deviation between the two.
To the engine 8 by controlling the amount of fuel supplied to the engine 8 by operating the actuator 23.
It operates so that the number of rotations of 1 is made to match the set number of rotations.

On the other hand, the vehicle speed control unit 10 adjusts the traveling speed of the harvester during the harvesting work to quickly match the traveling speed of the harvester with the limit vehicle speed Sx set by the rotational position of the vehicle speed setting lever 61, in the gearbox of the gearbox. is intended to perform the changing operation, the the input ports a _1, the provided automatic switch 11 is connected, the input port a ₁ by turning on of the switch 11 is turned to low level.

The input port a ₂ or the input port a ₃ engages or disengages the power to the threshing unit 3 or the reaping unit 4 and turns on the threshing switch 12 or 12 when the threshing clutch or the reaping clutch (not shown) is engaged. The mowing switches 13 are connected to each other, and when the threshing switch 12 is turned on, the input port a ₂ is turned to high level, and when the mowing switch 13 is turned on, the input port a ₃ is turned to high level.

Further, the input port a ₄ is connected to the output side of the comparator 51a, and the input port a ₄ turns to high level according to the high level output of the comparator 51a. The + input of the comparator 51a is
.. is a signal obtained by superimposing the outputs of the grain culm sensors 51, 51 ... And its negative input is a predetermined voltage set by the voltage divider 51b. Therefore, in the input port a ₄ , when the grain culm is in contact with the pressure receiving surfaces of the grain culm sensors 51, 51, ... And the + input potential in the comparator 51a becomes higher than the − input potential, that is, the threshing part 3 has already been cut. High level when grain culms are being delivered.

In the vehicle speed control unit 10, the input port a ₁ is at low level,
When the input ports a ₂ , a ₃ and a ₄ are all at high level, that is, when the automatic switch 11, the threshing switch 12 and the reaping switch 13 are all turned on, and the feeding of the grain culms is detected by the grain culm sensor 51. The control operation is performed only in the.

The input port a ₅ of the vehicle speed control unit 10 is connected to the vehicle speed setting lever.
The potentiometer 14 is attached to the base end pivotal support portion of 61 and outputs a potential according to the rotational position of the lever 61, and the input port a ₆ is connected to the shift sensor 15, respectively.
Further, the output signal of the rack position sensor 21 mounted on the engine 8 is given to the input port a ₇ . The input signals to the input ports a ₅ , a ₆ , and a ₇ are subjected to predetermined processing by the input interface of the vehicle speed control unit 10 and are adapted to be captured as digital data corresponding to each level, The vehicle speed control unit 10 uses the input signal to the input port a ₅ to set the vehicle speed limit Sx, and the input signal to the input port a ₆ to set the current gear ratio P in the continuously variable transmission.
Further, the current rack position R in the engine 8 is recognized by the input signal to the input port a ₇ .

On the other hand, the output ports b ₁ and b ₂ of the vehicle speed control unit 10
It is connected to the rotating shift motor 16 via a drive circuit (not shown), and is connected to the output port b ₁ (or the output port).
The shift motor 16 rotates in the normal direction (or reverse direction) according to the high level output of b ₂ ) and the shift lever 60 is rotated to the high speed (or low speed) running side. The outputs from the output ports b ₁ and b ₂ are pulse signals having a duty ratio D calculated as will be described later.

The output port b ₃ of the vehicle speed control unit 10 is a vehicle speed lamp for informing the operator that the vehicle speed control operation is being performed.
17 and the output port b ₄ are connected to an overload lamp 18 for informing the operator that the current load E in the engine 8 exceeds the upper limit value Emax, respectively, and the output port b ₃ or the vehicle speed ramp 17 or overload lamp 18 in response to the high level output of the b ₄ are respectively turned on.

The output port b ₅ of the vehicle speed control unit 10 is an output port that outputs a digital signal corresponding to the load E, and the output signal from the port b ₅ is at a position visible to the operator seated in the driver's seat DS. Is given to the load monitor 19 arranged in
The current load condition of the engine 8 is displayed on the monitor 19. 5 (a) and 5 (b) are
5 is a display example of the load monitor 19, and when the vehicle speed control unit 10 is not performing its control operation and the signal from the output port b ₅ is not given, the load monitor 19 is shown in FIG. As shown, the engine speed is displayed and the output port
At the same time that the signal from b ₅ is given, the operation is switched to operate in response to the signal, and as shown in FIG. 5 (b), the percentage of the current load E in the engine 8 with respect to the upper limit Emax is displayed. There is.

Further, the output port b ₆ of the vehicle speed control unit 10 is connected to the input side of the engine speed control unit 20, and the output port b ₆
When the corresponding input port of the engine speed control unit 20 becomes high level according to the high level output of the control unit 20, the control unit 20 maintains the speed of the engine 8 at the set speed as described above. Take control action.

An arithmetic expression for calculating the traveling speed S from the signal input to the input port a ₆ , an arithmetic expression for calculating the load E of the engine 8 from the signal input to the input port a ₇ , Various mathematical expressions and data necessary for the control calculation such as the upper limit value Emax of the load are stored in the ROM (read-only memory) of the vehicle speed control unit 10.

Now, regarding the operation of the device of the present invention configured as described above,
Description will be made based on the flowchart of FIG. 4 showing the control contents of the vehicle speed control unit 10.

Prior to the start of the harvesting operation by the ordinary harvester equipped with the device of the present invention, the work vehicle first determines the type of grain to be harvested,
The vehicle speed setting lever 61 is operated according to the harvesting conditions such as the planting density of the grain on the field surface, the turning position of the lever 61 is appropriately set, and then the threshing clutch and the reaping clutch are engaged. And the automatic switch 11 is turned on. As a result, the input ports a ₂ and a ₃ of the vehicle speed control unit 10 become high level and the input port a ₁ becomes low level. After that, the operator turns the shift lever 60 to rotate the harvester at an appropriate vehicle speed corresponding to the turning position. As a result, the grain culms on the field are harvested by the operation of the harvesting unit 4 as described above, and are conveyed to the threshing unit 3 through the feeder house 5.

Now, the grain culm conveyed in this way is the grain culm sensor 51.
When the input port a ₄ of the vehicle speed control unit 10 turns to a high level, all the operation start conditions are satisfied, and the control unit 10 starts its control operation, and first its output port b. _{3 is set} to the high level, the vehicle speed lamp 17 is turned on, the output port b _{6 is set} to the high level, and the engine speed control unit 20 is instructed to start its operation. Rotate at a constant speed at the rated speed. Therefore, thereafter, the harvester travels at a constant speed at a vehicle speed that is uniquely determined according to the rotational position of the shift lever 60.

Next, the vehicle speed control unit 10 reads the limiting vehicle speed Sx from the signal input to the input port a ₅ , and further determines the gear ratio P and the rack position R from the signals input to the input ports a ₆ and a _7. Read each. As mentioned above, the engine 8
Is maintained at the rated speed, the vehicle speed S of the harvester uniquely corresponds to the gear ratio P, and the load E of the engine 8 uniquely corresponds to the rack position R. Therefore, the vehicle speed control unit 10 reads it. Using the gear ratio P and the rack position R, the current vehicle speed S of the harvester and the current load E of the engine 8 are calculated in accordance with the arithmetic expression stored in the control unit 10, and the calculated load E is supported. Output signal from the output port b ₅ to be displayed on the load monitor 19, and the load E is compared with the upper limit value Emax of the load. If E is larger than Emax, the output port b ₄ is high level,
Turn on the overload lamp 18 and let the worker set the vehicle speed setting lever.
Prompt the rotation operation of 61 to the low speed side.

Next, the vehicle speed control unit 10 compares the previously calculated vehicle speed S with the limited vehicle speed Sx, and S is a predetermined dead zone width 2 with Sx at the center.
If it is within the range of S ', the counter n for counting the number of samplings is reset, the current load E is stored as E ₁ , and the above-mentioned respective values are read again so that the first value in the flowchart is read. Return to the stage. Meanwhile S
However, if it is out of the range, after adding 1 to the counter n, this is compared with a constant N indicating the number of sampling times required, and the above-described operation is repeated until the content of the counter n becomes N, While sampling is performed N times, the process proceeds to the next step only when the current vehicle speed S continues to be different from the limited vehicle speed Sx.

As described above, the engine speed of the engine 8 is maintained at its rated speed, and the vehicle speed S of the harvester is kept constant unless the gear ratio in the transmission is changed.
The vehicle speed control unit 10 only outputs the lights of the overload lamp 18 and the load monitor 19 at the time of normal harvesting work, but when the vehicle speed S is significantly different from the vehicle speed limit Sx immediately after the start of the operation, Alternatively, when the operator turns the vehicle speed setting lever 62 in order to change the vehicle speed limit Sx according to the lighting of the overload lamp 18 or the display content of the load monitor 19, N times of the predetermined sampling cycle is performed. While the sampling is performed, the current vehicle speed S may continue to be different from the restricted vehicle speed Sx, and in such a case, the vehicle speed control unit 10 performs the following to make the vehicle speed S of the harvester match the restricted vehicle speed Sx. Works like.

First, the vehicle speed control unit 10 represents the current vehicle speed of the harvester with the vehicle speed S calculated at the Nth sampling, and calculates the deviation ΔS (= | S−Sx |) between this and the speed limit vehicle Sx. Then, this is compared with the maximum deviation ΔSmax stored in advance, and the duty ratio D of the output signal from the output port b ₁ or b ₂ is calculated according to the comparison result. That is, when the calculated deviation ΔS is larger than the maximum deviation ΔSmax, the duty ratio D is set to the maximum duty ratio Dmax stored in advance in the vehicle speed control unit 10, and ΔS ≦ ΔSmax.
, The change rate Δ of the load E in the engine 8
E is calculated, and the duty ratio D is calculated by the following equation in order to change the duty ratio D according to this and the deviation ΔS. It should be noted that the change rate ΔE is calculated based on the current load E calculated at the Nth sampling and N−1
It is performed by dividing the difference from the value calculated at the previous sampling and stored as E ₁ as described above by the time N times the sampling period.

However, ΔE ₀ is a reference change rate, and D ₀ is a constant indicating a change rate of the duty ratio D, both of which are stored in the vehicle speed control unit 10 in advance.

After calculating the duty ratio D according to the equation (1),
The vehicle speed control unit 10 checks the magnitude relationship between the vehicle speed S and the limited vehicle speed Sx, and when S is smaller than Smax, outputs a pulse signal having a duty ratio D from the output port b ₁ for a predetermined time and shift motor. Rotate 16 forward to increase the vehicle speed, and conversely S
If it is smaller than Smax, the pulse signal is output from the output port b ₂ , and the shift motor 16 is operated to reversely rotate to reduce the vehicle speed, and then the current load E is changed to E ₁
In addition, the counter n is reset to return to the first stage of the flowchart to read the limit vehicle speed Sx, the gear ratio P and the rack position R, and the same operation is continued.

To read each of the above values, return to the first stage of the flowchart.

In this way, the duty ratio D of the pulse signal emitted from the output port b ₁ or the output port b ₂ to drive the shift motor 16 is the limit vehicle speed Sx and the current vehicle speed S, as is clear from the equation (1). The smaller the deviation ΔS between the two becomes smaller. Therefore, when the current vehicle speed S is sufficiently smaller than the vehicle speed limit Sx set by the vehicle speed setting lever 61, for example, when the harvesting operation is started by the harvester, the shift motor is first driven by a pulse signal having a large duty ratio D. 16 is driven in the normal direction, and as the vehicle speed S approaches the limited vehicle speed Sx as the gear ratio P increases, the shift motor
Since 16 is driven in the normal direction by the pulse signal having the small duty ratio D, the speed is rapidly increased at the start of the control, and the speed is gradually increased in the vicinity of the limited vehicle speed Sx to reduce the vehicle speed S. Can promptly and surely match the vehicle speed limit Sx.

Further, the second term of the equation (1) is a term for changing the duty ratio D according to the change rate ΔE of the load E,
When the load E shows a change rate ΔE larger (or smaller) than the standard change rate ΔE ₀ as a result of performing one acceleration or deceleration operation by the vehicle speed control unit 10, the second term is The duty ratio D becomes negative (or positive) and is smaller (or larger) than the standard duty ratio D determined by the first term.
Will be emitted from the output port b ₁ or b ₂ . For example, at the start of the above-described work, the load E in the engine 8 as a result of one speed increase shows a larger increase than the expected increase rate of the load, and the standard duty ratio D determined by the first term is determined. When it is expected that the increase rate of the load in the threshing section 3 and the mowing section 4 will become excessively large due to the speedup corresponding to the above, the operation of the second term causes the speedup to accompany the speedup. The degree of decrease of the duty ratio D is made large, and conversely, as a result of one speed increase, the load E shows a smaller increase than the expected increase rate of the load, and it is possible to adopt a larger duty ratio D. When it is determined that the duty ratio D is reduced by the function of the second term, the speed is increased more quickly.

FIGS. 6 and 7 are graphs showing the above-mentioned relationship between the duty ratio D and the vehicle speed S. FIG. 6 shows a case where a relatively large vehicle speed limit Sx is set by operating the vehicle speed setting lever 61. Further, FIG. 7 shows the case where a relatively small vehicle speed limit Sx is set. As is clear from these figures, when the deviation ΔS between the vehicle speed S and the vehicle speed limit Sx is larger than ΔSmax, the maximum duty ratio Dmax is adopted as the duty ratio D, and ΔS becomes ΔSmax or less. After that, depending on whether the difference between the load change rate ΔE and the standard change rate ΔE ₀ is positive or negative, a cross hatch below the straight line A representing the first term of the equation (1) is applied. The duty ratio D set in the area B shown or in the area C shown by hatching above the straight line A is adopted.

In this embodiment, as is clear from FIG. 6 and FIG. 7, the shift motor is driven by the duty ratio D calculated by the equation (1) regardless of the magnitude relationship between the vehicle speed S and the vehicle speed limit Sx. Although 16 is configured to rotate, when the device of the present invention is applied to an actual harvester, the vehicle speed S is the vehicle speed limit.
If it is larger than Sx and the load on the threshing section 3 or the working section such as the reaping section 4 is excessive, priority should be given to withdrawing from this overload state as soon as possible, It is preferable to calculate the duty ratio D irrespective of the load change rate ΔE by using an expression excluding the second term of the expression (1).

Further, in the present embodiment, the case where the ordinary harvester is equipped with the device of the present invention has been described, but the device of the present invention can be applied to other working vehicles such as a self-removing harvester and a tractor. Needless to say.

Further, in the present embodiment, the vehicle speed limit Sx that is the set speed is
Is set according to the display content of the load monitor 19 or the turning position of the vehicle speed setting lever 61 operated by the operator who visually recognizes the lighting of the overload lamp 18. In accordance with the load E calculated based on the detected result of the rack position sensor 21 that is set, the vehicle speed control unit 10 may automatically set the limit vehicle speed Sx in order to maintain the load E at an appropriate value. Is.

In the present embodiment, the engine 8 is described as being isochronously controlled, but the device of the present invention can be applied even if the engine 8 is a normal engine. In that case, the vehicle speed S is determined by the shift sensor 15. Calculated by the detection result of the engine rotation sensor 22 or the detection result of the engine rotation sensor 22, or a rotation speed detector is attached to the drive shaft of the traveling crawler 2, and the vehicle speed S is directly detected based on the detection result of the detector. It may be configured to.

Further, in the present embodiment, the rotation speed of the shift lever 60 is changed by changing the duty ratio D of the drive signal of the shift motor 16, but the speed changing means is not limited to this. Further, the arithmetic expression for calculating the duty ratio D is not limited to the expression (1).

〔effect〕

As described in detail above, in the device of the present invention, since the changing speed of the traveling speed setting position of the continuously variable transmission is changed based on the deviation between the current traveling speed and the set speed, when the deviation is large, In the initial stage, the traveling speed is changed promptly and is gradually changed as the deviation becomes smaller, so that the vehicle speed can be promptly and surely matched with the set speed, while if the deviation is small, the traveling speed is reduced. Since the speed is changed slowly, there is no risk of hunting, and the excellent effects such as the reliable realization of the set speed can be achieved.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a right side sectional view of a common harvester equipped with the device of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a configuration of the device of the present invention. FIG. 4 is a flow chart showing the control contents of the vehicle speed control section, FIGS. 5 (a) and 5 (b) are diagrams showing a display example of the load monitor, and FIGS. 6 and 7 are shift motors. 6 is a graph showing the relationship between the duty ratio of the drive signal and the current vehicle speed. 3 ... threshing section, 4 ... reaping section, 8 ... engine, 10 ...
Vehicle speed control unit, 15 …… shift sensor, 16 …… shift motor, 19 …… load monitor, 20 …… engine speed control unit,
50 …… Feed chain, 51 …… Grain ₁ sensor, 60 …… Shift lever, 61 …… Vehicle speed setting lever

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Wataru Nakagawa Wataru Nakagawa 1-32, Chayamachi, Kita-ku, Osaka, Yanmar Agricultural Machinery Co., Ltd. (56) References JP-A-60-98107 (JP, A) JP-A-60 -244225 (JP, A) Japanese Patent Publication No. 2-2571 (JP, B2) Actual Public Sho 61-45786 (JP, Y2)

Claims (1)

(57) [Claims] 1. A work vehicle equipped with a transmission capable of continuously changing a traveling speed adjusting position of the operating lever according to a rotational position of the operating lever so that the traveling speed of the vehicle coincides with a set speed. Therefore, in a vehicle speed control device for a working vehicle that changes a rotational position of the lever, a unit that calculates a deviation between the traveling speed and the set speed, and the rotational position is changed based on a calculation result of the unit. A vehicle speed control device for a working vehicle, comprising: a means for changing a speed.