JPH0722458B2 - Harvester vehicle speed controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle speed control device for a harvester that operates to change a traveling speed in accordance with a load increase / decrease in a working unit such as a threshing unit and a mowing unit. .

[Prior art]

The harvester conveys the grain culms cut by the mowing section to the threshing section, performs threshing and sorting processing at the threshing section, and extracts fine grains, and the working sections such as the mowing section and the threshing section. While the load of No. 1 increases and decreases according to the amount of grain culm to be treated in these, the amount of grain culm to be treated increases and decreases according to the traveling speed of the harvester, field conditions, and the like. Therefore, in the conventional harvester, under the proper load condition in the working section,
There is a vehicle speed control device that changes the traveling speed according to the increase or decrease of the load on the working unit so that the respective processes can be performed.

The conventional vehicle speed control device detects, for example, the load on the working unit by the number of rotations of the threshing unit in the threshing unit, and when this exceeds a preset appropriate range (or falls below), the grain to be processed in the working unit Decrease (or increase) culm volume,
In order to reduce (or increase) the load on the working unit, the traveling speed is reduced (or increased) by a predetermined amount, and the traveling speed is increased or decreased by changing the traveling speed stage of the transmission (Japanese Patent Application No. 60-168707 (JP-A-62-29909).

However, in such a vehicle speed control device, the detected value of the load of the working unit greatly deviates from the appropriate range,
If it is necessary to change the traveling speed stage multiple times to return this to the proper range, after changing the traveling speed stage once, the load on the working unit changes according to the changed traveling speed. It takes a long time until the proper traveling speed is realized, and in the meantime, in the working part, under the overload or underload condition, Therefore, there is a problem that the engine for driving the working unit is forced to operate under an overloaded condition or the working efficiency is reduced.

Therefore, a so-called isochronous-controlled engine that can rotate at a constant speed regardless of the size of the load is mounted on the harvester by adjusting the fuel supply amount according to the increase or decrease of the load, and the working unit and the traveling unit are driven by the engine. The load of the engine is detected by the position of the rack that adjusts the fuel supply amount of the engine, while the load characteristic is the relationship between the speed corresponding to each traveling speed stage of the transmission and the load of the engine. Based on the load characteristics, which are stored in advance and are based on the detection result of the engine load and the current traveling speed stage, the highest speed side such that the engine load after shifting becomes less than or equal to a preset upper limit value of the engine load. The above-mentioned difficulties can be solved by adopting a configuration in which the traveling speed stage is selected, the traveling speed stage of the transmission is changed to realize the traveling speed stage, and the traveling speed is changed.

[Problems to be solved by the invention]

However, the load of the working unit during the actual harvesting work includes a fluctuation component, and in the vehicle speed control device having the above-described configuration, the load at the traveling speed stage selected at an appropriate time is near the upper limit value, In addition, when the fluctuation component is large, the detected value of the engine load becomes the upper limit because the fluctuation component exists after the traveling speed stage is changed to the speed increasing side to realize the traveling speed stage. Value is exceeded, the traveling speed gear is changed to the deceleration side, and the previously selected traveling speed gear is selected again based on the detected value of the engine load thereafter, and the traveling speed gear is changed to the acceleration side. Then, the so-called hunting phenomenon in which the acceleration and deceleration are similarly repeated thereafter may occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle speed control device in which an optimum traveling speed stage is immediately selected based on a detection result of an engine load and a hunting phenomenon does not occur. To aim.

[Means for solving problems]

The vehicle speed control device for a harvester according to the present invention has an engine rotation speed control unit that operates to maintain the rotation speed of the engine at a set rotation speed regardless of the magnitude of the load. It is equipped with a harvester that is designed to drive,
The load of the working unit is detected as the load of the engine associated therewith, and based on the detection result, a traveling speed stage in which the load of the engine is equal to or less than a preset upper limit value is selected, In the vehicle speed control device of the harvester that changes the traveling speed stage of the transmission to realize the speed, and adjusts the traveling speed, within a predetermined time after the change to the speed increasing side of the traveling speed stage is performed, When the traveling speed stage is changed to the deceleration side, a means for reducing the upper limit value by a predetermined amount is provided.

[Action]

In the present invention, the speed after deceleration is reduced within a predetermined time after the change of the traveling speed stage to the speed increasing side in order to realize the traveling speed stage selected so as to be equal to or less than the upper limit value. When the traveling speed stage is changed to the side, the upper limit value is reduced and a new upper limit value is set, and thereafter, the traveling speed stage in which the load after acceleration is less than or equal to this upper limit value. Is selected.

〔Example〕

The present invention will be described below with reference to the drawings showing an embodiment thereof. FIG. 1 is an external perspective view of a harvester equipped with a vehicle speed control device according to the present invention (hereinafter referred to as the device of the present invention). In the figure, reference numeral 1 is a traveling crawler, and an engine (not shown)
Is transmitted to the traveling crawler 1 through the main clutch, the gear meshing auxiliary transmission, the main transmission using the power shift transmission, and the side clutch to drive the vehicle, while the traveling crawler 1 Upper part of the threshing part 3, a swinging selection device (both not shown), and the like, and a cutting blade 41 and a raising device 42 provided on the cutting part 4 at the front of the machine body.
Etc. are also driven by the driving force of the engine.

Reference numeral 6 in the drawing denotes an operation column provided on the side of the driver's seat DS. The operation column 6 is used to change the main shift lever 51 for changing the traveling speed stage of the main transmission and the traveling speed stage of the auxiliary transmission. The auxiliary shift lever 52, an accelerator lever 53 for changing the engine rotation speed, an automatic switch 9 for instructing the device of the present invention to start its operation, and the like are provided.

Further, 7 is a vertical transport chain, and its end is provided along the handling opening on the left side of the threshing unit 3, and the grain culm pinching and transporting device 8 is provided.
Of the feed chain 81, the grain culm cut by the reaper 4 is conveyed by the feed chain 81 and the pinching rod 82 of the vertical conveying chain 7 and the grain culm pinching and conveying device 8. Threshing processing is performed inside the threshing unit 3.

A grain culm sensor 71 is installed on the front surface of the threshing unit 3 in the vicinity of the end of the vertical transport chain 7, and the grain culm sensor 71 has a detection rod 72 protruding downward in the vertical transport chain 7. It is detected that the grain culm is fed to the threshing unit 3 by bringing it into contact with a part of the grain culm to be conveyed.

FIG. 2 is a block diagram showing the configuration of the device of the present invention.
Is a vehicle speed control unit, and 30 is an engine speed control unit. The engine speed control unit 30 detects the engine speed,
In order to match the detection result with the set rotational speed, a fuel rack of the fuel injection pump (hereinafter referred to as a rack) is moved to perform so-called isochronous control for controlling the fuel supply amount to the engine. On the side, the rack position sensor 31 is mounted coaxially with the rack and detects the position of the rack, for example, a rack position sensor 31 using an operating transformer, and is mounted at an appropriate position of the engine, and the rotation speed of the engine. Each of the engine rotation sensors 32 for detecting the engine speed is maintained, and an operation command signal is given from the vehicle speed control unit 10 as described later.

On the other hand, the output of the engine speed control unit 30 is an input port of the vehicle speed control unit 10 and a rack actuator 33 that drives the rack, for example, using a linear solenoid.
They are given respectively to a _8.

The engine speed control unit 30 includes a numerical table or an arithmetic expression for obtaining a corrected set speed that is set to restore the set speed to the set speed when the detected speed differs from the set speed due to a change in load. Of the correction setting rotational speed at the time of no load and the position of the rack that can obtain this, that is, a mathematical table or an arithmetic expression for obtaining the relationship between the rack position corresponding to the no load, the rack position corresponding to the no load and the detected rack position The rack position required to obtain the set number of rotations from, that is, a numerical table or an arithmetic expression for obtaining the target rack position, and the maximum allowable position of the rack at each number of rotations are stored.

Then, the engine rotation speed control unit 30 detects that the detected rotation speed input from the engine rotation sensor 32 due to the change in the load is the set rotation speed (the rated rotation speed in this embodiment).
If it is different from the above, the correction setting rotation speed is calculated, and the rack position corresponding to the correction setting rotation speed corresponding to the no-load is read,
From this and the actual rack position input from the rack position sensor 31, a target rack position required to obtain the corrected set rotational speed is calculated, and a signal corresponding to this target rack position is sent to the rack actuator 33. give. In response to this signal, the rack actuator 33 operates to move the rack to the target rack position and adjusts the fuel supply amount to the engine. In this way, the engine speed control unit 30 controls the engine speed regardless of the load.
The controller 30 operates to maintain the rated number of times, but the operation of the controller 30 is performed only when an operation command signal from the vehicle speed controller 10 is given, as described later.

On the other hand, the vehicle speed control unit 10 calculates the engine load from a signal corresponding to the target rack position given from the engine speed control unit 30, obtains a traveling speed stage that does not exceed the upper limit value, and realizes the traveling speed stage. Therefore, the traveling speed stage in the main transmission and the auxiliary transmission is changed.

The automatic switch 9 is connected to the input port a ₁ of the vehicle speed control unit 10, and when the switch 9 is turned on, the input port a ₁ turns to a low level. In addition, input ports a ₂ , a ₃ ,
a ₄ is a threshing switch 11 that is turned on when the threshing clutch is in the engaged state, a mowing switch 12 that is turned on when the mowing clutch is in the engaged state, and the detection rod of the grain culm sensor 71.
The grain stalk switches 13 that are turned on when the grain stalks come into contact with 72 are respectively connected, and by turning on each of these switches,
The input ports a ₂ , a ₃ , and a ₄ each turn to high level. Then, the vehicle speed control unit 10 determines that when each of the switches is turned on, that is, the input port a ₁ is at the low level,
It operates only when a ₂ , a ₃ and a ₄ are all at a high level to control the vehicle speed of the harvester.

Input ports a ₅ and a ₆ of the vehicle speed control unit 10 are connected to the auxiliary shift levers.
First and second auxiliary transmission switches 14 and 15 which are arranged at the base end of the lever 52 and are turned on and off depending on the locking position of the lever 52 are connected to the first auxiliary transmission switch 14, respectively. The input port a ₅ turns to a low level when turned on, and the input port a ₆ turns to a low level when the second auxiliary transmission switch 15 turns on. The auxiliary transmission device has three traveling speed stages, that is, "low speed stage", "medium speed stage", and "high speed stage". The second auxiliary shift switch 15 is turned on when the auxiliary shift lever 52 is in the locking position corresponding to the "low speed" and the auxiliary shift lever 52 is in the locking position corresponding to the "high speed". The vehicle speed control unit 10 is provided, because the input port a ₅ is at a low level,
By the fact that the speed stage of the auxiliary speed change device is a "slow stage", also has an input port a ₆ is at low level,
Similarly, the fact that it is a “high-speed stage” means that input ports a ₅ and a ₆
Both are at "high speed", so "medium speed stage"
Recognize that each is.

To the input port a ₇ of the vehicle speed control unit 10, a shift sensor 16 that is mounted on the base end pivotal support portion of the main shift lever 51 and outputs a potential according to the amount of rotation thereof and that uses a potentiometer is connected. . The main transmission has four forward speeds and one reverse speed.
The vehicle has six speed stages, namely, high speed and neutral speed stages, and the vehicle speed control unit 10 determines which state of the main speed device the travel speed stages are in, depending on the level of the signal input to the input port a ₇ . recognize.

Further, a signal corresponding to the target rack position which is the output of the engine speed control unit 30 is given to the input port a ₈ of the vehicle speed control unit 10 as described above.

The signals input to the input ports a ₇ and a ₈ are subjected to predetermined processing by the input interface of the vehicle speed control unit 10 and taken into the CPU 10a of the vehicle speed control unit 10 as digital data corresponding to the level of each signal. It is designed to work.

On the other hand, the output ports b ₁ and b ₂ of the vehicle speed control unit 10 are connected to the shift motor 20 for rotating the main shift lever 51 via a drive circuit (not shown), and the output port b ₁ (or b ₂ ) of the output port b ₁ (or b ₂ ). The shift motor 20 rotates forward (or reverse) according to the high level output.
Then, the main shift lever 51 is rotated to the high speed (or low speed) running side.

The output port b ₃ of the vehicle speed control unit 10 has a vehicle speed lamp 21 for informing the operator that the vehicle speed control operation is being performed.
The output ports b ₄ and b ₅ are respectively connected to a speed-up instruction lamp 22 and a speed-down instruction lamp 23 for instructing an operator to operate the auxiliary shift lever 52 on the speed-up side and the speed-down side. , the output port b _3, b ₄ each lamp in accordance with the low level output of, b ₅ is adapted to be respectively turned on.

The output port b ₆ of the vehicle speed control unit 10 is connected to a buzzer 24 for outputting various alarms, and the buzzer 24 sounds according to the high level output of the output port b ₆ .

The output port b ₇ of the vehicle speed control unit 10 is connected to the input side of the engine speed control unit 30, and the engine speed control unit connected to the output port b ₇ according to the high level output of the output port b _7. When the input port of 30 becomes high level, the control unit 30 operates as described above, and causes the engine of the harvester to rotate at its rated speed at a low speed regardless of the load applied thereto.

The vehicle speed control unit 10 is a CPU 10a that performs input instructions and control calculations,
The CPU 10a includes a RAM 10b used for control calculation, a ROM 10c storing various data and control programs necessary for control calculation, and the like. FIG. 3 is a graph of load characteristics showing the relationship between the traveling speed of the harvester and the load of the engine when the engine speed is the rated speed.
It is stored in the ROM 10c as one of the above-mentioned data. The horizontal axis of FIG. 3 shows the traveling speed V and the vertical axis shows the load factor E with respect to the maximum load of the engine, and F _{1 to} F _n actually perform harvesting work under various different load conditions. It is a load characteristic curve obtained by.

In addition, L1 to L4, M1 to M4 and H1 and H2 in FIG. 3 are symbols indicating traveling speed stages, and L, M, and H are the traveling speed stages in the auxiliary transmission, respectively. , "Medium speed stage", "high speed stage", 1,2,3,4, the traveling speed stage in the main transmission is "forward 1st speed stage", "forward 2nd speed stage", It indicates that it is a “third forward speed” and a “fourth forward speed”. As described above, the graph of FIG. 3 was obtained under the condition that the engine is rotating at a constant speed at the rated speed, and therefore the symbols indicating the traveling speed stages are as follows:
It corresponds to the traveling speed. Furthermore, E _{cmax in} Fig. 3
Is the limit maximum load ratio, which is the upper limit value of the load for limiting the load applied to the engine during vehicle speed control operation, and is set to 85 to 90% of the maximum load of the engine.
Remembered in.

Now, the operation of the device of the present invention configured as described above will be described with reference to the flowcharts showing the control contents of the vehicle speed control unit 10 in FIGS. 4 and 5.

When the vehicle speed control unit 10 is connected to the power supply by turning on the key switch for starting the engine, first, the vehicle speed control unit 10 monitors the on / off state of the automatic switch 9 by the level of the input port a ₁ . Then, when the automatic switch 9 is turned on and the input port a ₁ changes to the low level, then the input port a ₂
Depending on the level of ~ a ₄ , threshing switch 11, reaping switch 12
And, the on-off state of the grain culm switch 13 is checked, all of these switches are turned on, and the vehicle speed control unit 10 starts the vehicle speed control operation at the time when all of the input ports a _{2 to} a ₄ become high level, First, the output port b ₃ is turned to a low level, the vehicle speed lamp 21 is turned on to notify the operator that the vehicle speed control operation is being performed, and at the same time, the output port b _{7 is set} to a high level to control the engine speed. Part 30
The operation command is issued to the engine and the operation of the control unit 30 causes the engine to rotate at a constant speed thereafter at its rated speed.

Next, the vehicle speed control unit 10 sets the limit load factor, which becomes the reference of the subsequent vehicle speed control operation, by setting the coefficient K for setting the maximum limit load factor Ecmax by 1 as an initial value.
give. After that, the vehicle speed control unit 10 selects the traveling speed stage on the highest speed side to obtain the highest work efficiency under the condition that the load factor in the engine does not exceed the limit load factor K · Ecmax, and the traveling speed stage is selected. Change the running speed by operating to achieve.

After giving an initial value of 1 to the coefficient K, the vehicle speed control unit 10
Further inputs the rack position R according to the level of the input signal to the input port a ₈ , and further inputs the traveling speed stage (hereinafter referred to as main shift stage) A in the main transmission by the level of the input signal to the input port a ₇ . The traveling speed stage (hereinafter referred to as the auxiliary shift stage) B in the auxiliary transmission is recognized based on the levels of the ports a ₅ and a ₆ , respectively, and then the rack position R is used to calculate the engine speed based on the arithmetic expression stored in the ROM 10c. An input load factor ε corresponding to the current load factor is calculated. Then, the vehicle speed control unit 10 sets the input load factor ε to the limit load factor K · Ecma.
If ε is less than or equal to K · Ecmax as compared with x, the vehicle speed control operation according to the speed-up control subroutine described later is performed, and if ε is greater than K · Ecmax, the main transmission or the sub-transmission is performed. The traveling speed stage of the device is the current main shift stage A
Alternatively, the following operation is performed in order to change from the auxiliary shift stage B to the one-stage lower speed side.

That is, when ε is larger than K · Ecmax, the vehicle speed control unit 10 first starts the time measurement at the time when the speed increasing control operation according to the speed increasing control subroutine is finished, and the contents of a timer t ₃ described later. Is compared with a preset predetermined time T _3, and when t ₃ is larger than T ₃ , a predetermined value (0.05 in this embodiment) is subtracted from the value of the coefficient K, and t ₃ is
If T ₃ or less, the value of the coefficient K remains unchanged,
Next, it is checked whether or not the current main gear A is 1, and if A is not 1 and deceleration is possible by changing the main gear, the output port b _{2 is set} to a high level and the shift motor 20
Is reversed by a predetermined amount to change the main shift stage by one step. Also A
If 1 is 1, then it is checked whether or not the sub-shift stage B is L (low speed stage). If B is not L and deceleration is possible by changing the sub-shift stage, the output Set port b ₅ to low level, turn on deceleration instruction lamp 23, and
The operator is instructed to operate the low speed side of 52, and the levels of the input ports a ₅ and a ₆ are monitored to check whether or not the auxiliary shift lever 52 has been operated. _{At the} time interval of ₁ sec, output port b _{6 is set} to high level and the buzzer
Ring 24 intermittently.

When deceleration is performed by changing the main shift stage or the sub shift stage in this way, the threshing unit 3 is decelerated according to the traveling speed after deceleration.
The predetermined time (T ₂ ) set in consideration of the time required until the amount of grain culm sent to
sec) After waiting, the vehicle speed control unit 10 determines whether the above conditions for starting the vehicle speed control are satisfied, that is, the automatic switch.
9, threshing switch 11, reaping switch 12 and grain culm switch 13
Is turned on, and if this is satisfied, the process returns to the stage where the rack position R, the main gear A and the sub gear B are recognized, and the same operation is repeated thereafter.
If the above conditions are not satisfied, the vehicle speed control unit
In the standby mode 10, the vehicle speed lamp 21 is turned off, the operation of the engine speed control unit 30 is stopped, and the vehicle speed control operation is suspended until the above condition is satisfied.

Further, when the current main gear A is 1 and the sub gear B is L and it is impossible to reduce the traveling speed by changing the gear, the vehicle speed control unit 10 outputs the output port.
The b ₂ to the high level, the main gear is reversely rotates the shift motor 20 until neutral, to stop the aircraft, and the output port b ₆ to the high level causes the buzzer 24 for a predetermined time ringing, the output port b ₃ Is set to a high level and the vehicle speed lamp 21 is turned off, and then the control operation is ended. This is a state in which an excessive load is applied to any part of the working parts such as the threshing part 3 and the mowing part 4. In this case, the operator temporarily stops the engine and inspects each part. After removing the cause of the excessive load, the vehicle speed control unit 10 restarts the operation by operating the key switch and restarting the engine.

As described above, the input load factor ε limits the load factor K · Ecmax.
When ε is less than K · Ecmax when compared with
The vehicle speed control unit 10 operates according to the speed-up control subroutine whose flowchart is shown in FIG.

In the speed-up control subroutine, first, the current load state is specified from the input load factor ε and the current main shift stage A and the sub shift stage B, and the load characteristic curves that match this are F _{1 to} F shown in FIG. Selected from _n . For example, if the current traveling speed stage is “M3” and the input load factor is ε, the current load state is specified at point C in FIG. 3 and the load characteristic curve indicated by Fi in FIG. Is selected.

Then, the vehicle speed control unit 10 determines that the traveling speed stage “H
2 ”in this order, the load factor Ei on the load characteristic curve Fi at each traveling speed stage up to the traveling speed stage one step higher than the traveling speed stage corresponding to the current main transmission stage A and the sub transmission stage B. Is calculated and compared with the limit load factor K · Ecmax, and the main shift stage a and the sub shift stage b at the time point when Ei becomes smaller than K · Ecmax are set as the target traveling speed stages, and these are realized. Therefore, as will be described later, the traveling speed stage in the main transmission and / or the auxiliary transmission is changed to increase the traveling speed, and the load factors Ei calculated at the respective traveling speed stages are all the limited load factors. If it is equal to or more than K · Ecmax, it is determined that the current main gear stage A and the sub gear stage B are the optimum traveling speed stages, and the speed increasing control operation is not performed.
The control operation according to the speed-up control subroutine is immediately terminated, and the process returns to the predetermined stage in the flowchart of FIG.

Now, taking the case where the coefficient K is 1 and the current load state is specified at point C in FIG. 3 as an example, the current traveling speed stage is "M3" as described above. The load factors Ei at the stages “H2”, “H1”, and “M4” are calculated in this order. In this case, as is apparent from FIG. 3, the load factor Ei at “H2” and “H1” is the limit load factor K ·
It is larger than Ecmax, and the load factor Ei calculated in “M4” is below the limit load factor K · Ecmax for the first time.
The target travel speed stage a is 4, and the target travel speed stage b is M. As in the case of the previous example, the current traveling speed stage is "M3", the input load factor is ε'in FIG. 3, and the current load state is specified at point C'in FIG. When the rate characteristic curve Fj is selected, the load characteristic curve is
The load factors Ej required at the traveling speed stages “H2”, “H1”, and “M4” on Fj are all equal to or more than the limit load factor K · Ecmax, so that the current traveling speed stage “M3” is optimal. It is determined to be the speed stage, and the traveling speed stage is maintained as "M3".

When the target traveling speed stages a and b are obtained and the speed increasing control operation is required, the vehicle speed control unit 10 first sets the timer t for measuring the elapsed time after the speed increasing control operation is completed. ₃
Is reset, and then the current sub-gear B is compared with the target sub-gear b, and if B = b, the output port b _{1 is set} to a high level and the main gear becomes the target main gear a. The shift motor 20 is normally rotated up to and the traveling speed is increased by changing the main gear position. If B ≠ b, the vehicle speed control unit 10 sets the output port b ₄ to the low level to increase the output port b ₄ in order to instruct the operation of the auxiliary shift lever 52 to the speed increasing side similarly to the deceleration control operation described above. The speed instruction lamp 22 is turned on, and the sub-shift stage reaches the target sub-shift stage b until the sub-shift stage reaches the target sub-shift stage b.
At the time interval of T ₁ sec, the output port b _{6 is set} to the high level and the buzzer 24 sounds intermittently.

When the operation of the sub-shift lever 52 is performed and it is confirmed by the levels of the input ports a ₅ and a ₆ that the sub-gear has become b, the main gear is immediately set to the target main gear a. The operation of. After changing the traveling speed stage for speeding up in this way, the vehicle speed control unit 10 waits for a predetermined time T ₂ sec as in the case after changing the traveling speed stage for deceleration described above, and thereafter. The timer t ₃ starts counting the time, the control operation according to the speed-up control subroutine is ended, and the process returns to the predetermined stage in the flowchart of FIG. And the vehicle speed control unit 10
Confirms whether the conditions for starting the control described above are satisfied, and if they are not satisfied, the standby mode described above is entered, and if satisfied, a new rack position R,
The main shift stage A and the sub shift stage B are recognized, and a series of vehicle speed control operations are continued based on these.

Now the timer t ₃ is reset at the time when the load factor Ei calculated in the speed increasing control subroutine is determined to be required is small, and the speed higher than the limit load factor K · ECmax, for speed increasing The change of the driving speed stage of
It is designed to start timing after T ₂ sec has elapsed,
On the other hand, when the input load factor ε becomes larger than the limit load factor K · Ecmax and it is determined that deceleration is required,
When the content of the timer t ₃ is less than the predetermined time T ₃ , the predetermined value of 0.05 is subtracted from the coefficient K for setting the limited load factor.

That is, in the vehicle speed control unit 10, when it is determined that deceleration is necessary before the predetermined time T ₃ has elapsed after the acceleration control operation is performed, the limit load factor K · Ecmax after that is determined.
The coefficient K is reduced by 0.05 in order to reduce the hunting phenomenon, thereby preventing the hunting phenomenon. For example, when the coefficient K is 1 and the limited load factor is Ecmax, based on the load state specified at the point C in FIG. 3, until the traveling speed stage becomes “M4” as described above. If the speed-up control operation is performed, the input load factor ε after waiting for T ₂ sec becomes equal to the load factor Ei in FIG. 3, and should be smaller than the limited load factor Ecmax. However, since the actual load on the working unit fluctuates, and the input load factor ε fluctuates, this is the time before the elapse of the predetermined time T _3.
It becomes larger than Ecmax, the deceleration control operation is performed, and C again
It may be in the state of dots. In such a case, the coefficient K is thereafter set to 0.95, and the limited load factor is 0.95 · Ecmax (3rd
(See the figure), which is smaller than the load factor Ei corresponding to the traveling speed stage "M4" on the load characteristic curve Fi, as is clear from FIG. As long as there is no speed increase control operation according to the speed increase control subroutine is performed thereafter,
Held at 3 ”, the harvester will run at a speed equivalent to“ M3 ”. Further, after the coefficient K is set to 0.95, the speed increasing control operation is performed again, and before the predetermined time T ₃ elapses, deceleration is necessary due to the change in the input load factor ε after speed increasing as described above. If it is determined that the coefficient K is further reduced by 0.05, the limited load factor becomes 0.9 · Ecmax, and thereafter, the vehicle speed control operation in the vehicle speed control unit 10 is performed with this value as a reference.

Note that the hunting phenomenon occurs, and the procedure for setting a new limited load factor is not limited to the procedure shown in the present embodiment, and the current limited load factor is multiplied by a predetermined value, for example, 0.95 to obtain a new limited load factor. May be set, and further, the value of the limit load factor in every case is set in advance to the limit maximum load factor Ec.
It may be stored in the ROM 10c in the same manner as max, and one of these may be read out if necessary.

6 and 7 are flowcharts showing another embodiment of the present invention. In this case, the calculated load factor Ei in the acceleration control subroutine of FIG.
When it becomes smaller than Ecmax and it is necessary to change the traveling speed stage to the target traveling speed stages a and b, the vehicle speed control unit 10 next calculates the difference ΔE between the limited load factor K · Ecmax and the load factor Ei. Then, this is compared with a preset minimum value ΔEmin close to 0, and when ΔE is equal to or less than ΔEmin, from the coefficient K,
After subtracting 0.05, if ΔE is larger than ΔEmin, the value of the coefficient K is kept as it is and the required traveling speed stage is changed. The minimum value ΔEmin is obtained by actually performing harvesting work, the calculated load factor Ei is smaller than the limit load factor K · Ecmax, and the limit load factor K
When the difference with respect to Ecmax is smaller than this minimum value ΔEmin, the target traveling speed stage a corresponding to this load factor Ei
If and b are realized, it is necessary to change the traveling speed stage to the deceleration side within a predetermined time after that, and it is expected that the acceleration and deceleration will be repeated thereafter. Therefore, the vehicle speed control unit
10 is the limit load factor K when ΔE is equal to or less than ΔEmin
-0.05 is subtracted from the coefficient K in order to reduce Ecmax by a predetermined amount. As a result, after operating to achieve the target travel speed stages a and b, the travel speed stage is once changed to the deceleration side according to the flowchart of FIG. 6, but thereafter, the limited load factor K · Ecmax is changed. Because of the reduction, the traveling speed stage is not changed to the speed increasing side even if the speed increasing control subroutine is performed again unless the load state in the working unit changes.

〔effect〕

As described above in detail, in the device of the present invention, the speed is increased within a predetermined time after the speed is increased to realize the traveling speed stage selected so that the load after the speed increase is equal to or less than the upper limit value. In this case, the upper limit value is reduced and a new upper limit value is set, and thereafter, the traveling speed stage is selected so as to be less than or equal to this upper limit value, so that the traveling speed stage is lower than the previously selected traveling speed stage. The traveling speed stage on the side is selected, and excellent effects such as no occurrence of a hunting phenomenon are exhibited.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a perspective view of a harvester equipped with the device of the present invention, FIG. 2 is a block diagram showing the configuration of the device of the present invention, and FIG. Is a graph showing the relationship between the engine load and the engine load, FIGS. 4 and 5 are flowcharts showing the control contents of the vehicle speed control unit, and FIGS. 6 and 7 are flowcharts in another embodiment of the present invention. 3 ... Threshing unit, 4 ... Mowing unit, 9 ... Automatic switch, 10 ... Vehicle speed control unit, 14, 15 ... Sub-shift switch, 16 ... Shift sensor, 2
0 ... Shift motor, 30 ... Engine speed controller

Claims (1)

[Claims] Claim: What is claimed is: 1. An engine speed control unit is provided which operates to maintain the engine speed at a set speed regardless of the magnitude of the load, and the running unit and the working unit are driven by the engine. The load of the working unit provided in the harvester is detected as the load of the engine related thereto, and based on the detection result, the traveling speed stage in which the load of the engine becomes equal to or lower than a preset upper limit value. In the vehicle speed control device of the harvester for changing the traveling speed stage of the transmission to realize the speed stage and adjusting the traveling speed, the traveling speed stage is changed to the speed increasing side. A vehicle speed control device for a harvester, comprising means for reducing the upper limit value by a predetermined amount when the traveling speed stage is changed to a deceleration side within a predetermined time later.