JP2020080657A - Work vehicle - Google Patents

Abstract

To suppress a sudden change in a traveling speed by operating a setting dial while traveling.SOLUTION: A work vehicle includes: a speed change operation tool 13 operated in a fixed operation range for changing a traveling speed; a speed change device 9 for shifting the power from a power source 8 and transmitting the power to a traveling device 1, while being changed to a speed change state according to an operation position of the speed change operation tool 13 by the operation of the speed change operation tool 13; a correspondence setting tool 14 for changing correspondence between the operation position and the speed change state; and a change rate control part 25 for controlling a change rate of the speed change state in a range equal to or lower than a preset upper limit when the correspondence setting tool 14 is operated.SELECTED DRAWING: Figure 3

Description

The present invention relates to a work vehicle including a speed change mechanism that changes the power of an engine and transmits the power to a traveling device.

For example, Patent Document 1 describes a conventional combine. This combine includes a speed change operation tool for speed change operation (“speed change lever” in the same document) and a pump swash plate of a hydrostatic continuously variable transmission (HST) when the speed change operation tool is operated to the maximum operation position. A setting dial capable of continuously changing and setting the maximum inclination angle is provided. That is, in this combine, the inclination angle of the pump wheel plate of the HST corresponds to the operation position of the setting dial and the operation position of the setting dial. Although it is possible to control the traveling speed with the speed change operation tool, when performing work traveling, the speed change operation tool and the setting dial are used to adjust the travel speed to a speed suitable for the field to be worked, and Carry out work while maintaining the running speed. For example, even if the operator is unfamiliar with the operation, if the speed change operation tool is set to the maximum operation position and the setting dial is adjusted to an appropriate traveling speed, the speed change operation can be performed during work. Even if it is necessary to change the traveling speed with the gear, it is possible to easily return to the optimum traveling speed only by operating the gear shift operation tool to the maximum operating position.

JP, 2011-110020, A

If the setting dial is mistakenly operated during work traveling, the maximum tilt angle of the pump swash plate will be changed instantly and unintentionally due to the characteristic of the dial type operating tool that the operating range is smaller than the lever. , The traveling speed changes rapidly. For example, when the setting dial is operated to increase the maximum tilt angle of the pump swash plate during running, the vehicle accelerates rapidly. On the contrary, when the maximum inclination angle of the pump swash plate becomes small during traveling, the vehicle decelerates rapidly. Such a rapid change in traveling speed causes an accident during traveling or work and is dangerous.

It is an object of the present invention to suppress a sudden change in traveling speed caused by operating a setting dial during traveling.

In order to achieve the above object, a work vehicle according to an embodiment of the present invention is operated within a certain operation range to change a traveling speed and a traveling power source by changing power from a power source. A transmission device which is transmitted to the device and is changed to a shift state according to an operation position of the shift operation tool by operating the shift operation tool, and a correspondence relationship setting tool which changes a correspondence relationship between the operation position and the shift state. And a change rate control unit that controls the change rate of the shift state within a range equal to or less than a predetermined upper limit value when the correspondence relationship setting tool is operated.

With such a configuration, when the traveling speed changes with the operation of the setting operation tool, it is possible to suppress a rapid speed change, so that smooth traveling can be realized and the danger to the operator is suppressed. be able to.

The change rate control unit controls the change rate within a range of the upper limit value or less when the change rate exceeds a predetermined threshold value, and changes the threshold value to change the threshold value. It is preferable to provide a part.

By setting a threshold value separately from the upper limit value of the shift state change rate, a threshold value with a margin is set, and when the shift state change rate exceeds the threshold value, the shift state change rate Control can be performed. Further, by making the threshold value variable, it is possible to control the rate of change of the shift state with an appropriate threshold value according to the running state. As a result, the traveling speed can be gently changed in a more appropriate state according to the traveling state.

Further, the change rate control unit may control the change rate within the range of the upper limit value or less when the operation amount of the correspondence relationship setting tool per unit time is a predetermined value or more.

Since the rate of change of the shift state can be determined by the operation amount of the setting operation tool per unit time, it can be easily determined whether or not the rate of change of the shift state exceeds the upper limit value.

Further, it is preferable that the change rate control unit gradually increases the change rate.

With such a configuration, the rate of change of the shift state can be smoothly changed, smoother running can be realized, and it is possible to suppress the danger to the operator.

Further, the upper limit value may be different during acceleration and during deceleration.

Further, it is preferable that the upper limit value during acceleration is larger than the upper limit value during deceleration.

The shock the driver receives when the speed changes rapidly feels greater during deceleration than during acceleration. Therefore, at the time of deceleration, even if the rate of change of the shift state is small, by controlling the rate of change of the shift state, the shock received by the operator can be reliably reduced in an appropriate state.

It is the whole side view showing a combine. It is a schematic diagram showing an important section of an operation panel. It is a figure which shows a power transmission structure and a control structure together. It is a figure which shows the flow of swash plate control performed when changing a speed setting dial. It is a figure explaining the change of the running speed at the time of changing a speed setting dial. It is a figure explaining the change of the running speed at the time of changing the speed setting dial in another embodiment. It is a figure which illustrates the structure of a display apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings by taking a combine as a work vehicle as an example. Regarding the direction, the symbol F in FIG. 1 indicates the forward direction (forward direction) of the combine, and the symbol R in FIG. 1 indicates the backward direction (rear direction) of the combine.

[About the basic structure of the combine]
The combine shown in FIG. 1 is configured to be self-removing. The combine fuselage includes a pair of crawler-type left and right traveling devices 1, a frame-shaped vehicle body frame 2 supported by the traveling device 1, a mowing unit 3 supported by a front portion of the vehicle body frame 2, and a mowing unit 3. A threshing device 4 supported by the body frame 2 at the rear of the grain, a grain storage part 5 arranged on the right lateral side of the threshing device 4, an unloader 6 capable of discharging the grain stored in the grain storage part 5, A driving unit 7 and the like for a driver (operator) to perform a driving operation are provided.

The combine harvester cuts the planted grain culms in the field in the mowing unit 3 while traveling the machine with the traveling device 1, threshes the harvested grain culm with the threshing device 4, and stores the grains obtained by the threshing process in the grain storage. It is designed to be stored in the section 5. The grain stored in the grain storage unit 5 can be discharged outside the machine by the unloader 6.

As shown in FIG. 3, the combine is composed of an engine 8 as a power source, a continuously variable transmission 9 (corresponding to “transmission”) composed of HST which is a hydrostatic continuously variable transmission, and a gear mechanism. The transmission 10 is provided.

As shown in FIG. 3, the continuously variable transmission 9 is configured to change the power of the engine 8 and transmit the power to the traveling device 1 and the cutting unit 3. The continuously variable transmission 9 includes a variable displacement hydraulic pump 9A (main transmission) and a variable displacement hydraulic motor 9B (subtransmission) driven by pressure oil from the hydraulic pump 9A. The angle of the swash plate of the hydraulic pump 9A is changed by driving the actuator 11 composed of a servo cylinder or the like. The angle of the swash plate of the hydraulic motor 9B is changed by driving another actuator (not shown). By changing the angle of the swash plate of the hydraulic pump 9A, the continuously variable transmission 9 can change the speed ratio continuously. Further, by changing the angle of the swash plate of the hydraulic motor 9B, the power output from the continuously variable transmission 9 is switched between a low speed shift state for work traveling and a high speed shift state for normal traveling. It is possible to

As shown in FIG. 3, the transmission 10 is configured to shift the power input from the continuously variable transmission 9 and transmit the power to the traveling device 1 and the mowing unit 3.

As shown in FIG. 3, the power from the engine 8 is output to the continuously variable transmission 9, which is steplessly changed by the continuously variable transmission 9 and output to the transmission 10. The power of the transmission 10 is transmitted to the traveling device 1 and the mowing unit 3. In addition to being output to the continuously variable transmission 9, the power from the engine 8 is also output to the threshing device 4, the unloader 6, and the like without being subjected to the shifting action of the continuously variable transmission 9. Power transmission is turned on and off between the transmission 10 and the traveling device 1, between the transmission 10 and the mowing unit 3, between the engine 8 and the threshing device 4, and between the engine 8 and the unloader 6. A clutch (not shown) capable of being inserted is interposed.

As shown in FIGS. 1 and 2, the driver 7 is provided with a driver's seat 12 on which a driver can sit and an operation panel 7a. The operation panel 7a is a rocking-type shift lever 13 (for operating the angle of the swash plate of the hydraulic pump 9A (see FIG. 3)) of the continuously variable transmission 9 (see FIG. 3). ), a push-operation type auxiliary shift switch 13A for shifting operation of the continuously variable transmission 9 (for operating the angle of the swash plate of the hydraulic motor 9B (see FIG. 3)), the operating position of the shift lever 13 and the continuously variable A speed setting dial 14 (corresponding to "correspondence setting tool") for setting the correspondence relationship between the transmission 9 (see FIG. 3) and the swash plate of the hydraulic pump 9A (see FIG. 3), and other various manual operation tools ( (Not shown), a display device 15 including a meter panel and the like.

As shown in FIG. 3, the shift lever 13 is one of the operating tools used to control the traveling speed. The angle of the swash plate of the hydraulic pump 9A of the continuously variable transmission 9 is controlled according to the operation position of the speed change lever 13. The speed setting dial 14 is used when adjusting the angle of the swash plate of the hydraulic pump 9A, which is determined according to the operation position of the speed change lever 13. Specifically, when the shift lever 13 is operated, the angle of the swash plate of the hydraulic pump 9A is controlled according to the correspondence relationship of the shift state corresponding to the operation position of the shift lever 13, and further, the speed setting dial 14 is moved. When operated, this correspondence is changed according to the setting position (operating position) of the speed setting dial 14. As a result, the angle of the swash plate of the hydraulic pump 9A has a corresponding relationship with the operating position of the speed change lever 13 and the setting position of the speed setting dial 14. In other words, the traveling speed is controlled according to the operation position of the shift lever 13 and the setting position of the speed setting dial 14.

With this configuration, when the work traveling is performed, the traveling speed is adjusted to the speed suitable for the field to be worked by using the speed change lever 13 and the speed setting dial 14, and the traveling traveling is performed while maintaining the traveling speed. You can go. For example, if the speed setting dial 14 is operated and the traveling speed is adjusted appropriately while the gear shift lever 13 is at the maximum operation position, even if an operator unfamiliar with the operation is in control, When the traveling speed is changed by the speed change lever 13, it is possible to easily return to the optimum traveling speed simply by returning the speed change lever 13 to the maximum operation position.

As shown in FIG. 3, the shift lever 13 can be rocked between a forward maximum operating position Fmax and a reverse maximum operating position Rmax sandwiching the neutral position N. When the speed change lever 13 is operated to the neutral position N, the swash plate of the hydraulic pump 9A of the continuously variable transmission 9 becomes the neutral angle, and the power is not output from the continuously variable transmission 9. As a result, the power is not output to the traveling device 1. When the shift lever 13 is operated from the neutral position N toward the forward maximum operating position Fmax, the swash plate of the hydraulic pump 9A of the continuously variable transmission 9 is angularly changed from the neutral angle to the forward angle side. The forward power is output from the stage transmission 9. As a result, the traveling device 1 is driven forward. When the shift lever 13 is operated from the neutral position N toward the reverse-side maximum operation position Rmax, the swash plate of the hydraulic pump 9A of the continuously variable transmission 9 is changed from the neutral angle to the reverse angle side, and The reverse power is output from the stage transmission 9. As a result, the traveling device 1 is driven backward.

The speed setting dial 14 shown in FIG. 3 changes the speed change state indicating the correspondence between the operation position of the speed change lever 13 and the swash plate of the hydraulic pump 9A. As described above, when the shift lever 13 is operated, the angle of the swash plate of the hydraulic pump 9A is changed (the shift state is changed) to an angle corresponding to the operation position of the shift lever 13 based on the correspondence. The speed setting dial 14 changes the shift state by changing the angle of the swash plate of the hydraulic pump 9A corresponding to the operation position of the shift lever 13 according to the set position. As a result, even when the gear shift lever 13 is fixed, the traveling speed can be adjusted within a certain range by adjusting the speed setting dial 14. For example, the speed setting dial 14 can set the actual traveling speed at a rate of the speed corresponding to the operation position of the speed change lever 13, and can continuously select 50% to 100%. When the speed setting dial 14 is set to 100%, the traveling speed becomes the speed corresponding to the operation position of the shift lever 13. When the speed setting dial 14 is set to 70%, the traveling speed is 70% of the speed corresponding to the operation position of the shift lever 13.

The auxiliary shift switch 13A shown in FIG. 3 is an operation tool that can switch the state of the hydraulic motor 9B of the continuously variable transmission 9 between a low speed shift state for work traveling and a high speed shift state for normal traveling. The auxiliary shift switch 13A is provided on the grip 16 of the shift lever 13. The auxiliary transmission switch 13A can be operated by the fingers of the hand holding the grip 16.

[Control configuration]
As shown in FIG. 3, the combine includes a control device 17 for controlling the traveling speed and the information displayed to the operator. The control device 17 detects the operation signal of the speed change lever 13, the detection signal of the potentiometer 18, the operation signal of the auxiliary transmission switch 13A, the detection signal of the setting position of the speed setting dial 14, and the rotation speed of the engine 8 for detecting the actual rotation speed. The output signal of the sensor 19, the output signal of the swash plate angle sensor 20 that detects the angle of the swash plate of the hydraulic pump 9A of the continuously variable transmission 9, the output signal of the vehicle speed sensor 21 that detects the traveling speed of the machine body, etc. are input. ..

As shown in FIG. 3, the control device 17 includes a main shift control unit 22 and a speed control unit 23 that control the continuously variable transmission 9, and a display output unit 24 that controls information output to the display device 15. .. The speed control unit 23 includes an acceleration control unit 25 (corresponding to “change rate control unit”). The control device 17 is composed of one or more ECUs, a CPU, and the like. Further, the acceleration control unit 25, the main shift control unit 22, and the speed control unit 23 may each be composed of an independent ECU or the like, but the functions may be distributed to a plurality of ECUs or the like. Further, the control performed by the acceleration control unit 25, the main shift control unit 22, and the speed control unit 23 is not limited to hardware, and may be executed by a program. In this case, the program is stored in a storage device (not shown) and executed by the ECU, the CPU, or the like. Further, the change of the angle of the swash plate of the hydraulic pump 9A by the operation of the speed change lever 13 and the speed setting dial 14 may be performed based on the data indicating the correspondence relationship of the speed change state stored in the storage device (not shown). The angle of the swash plate of the hydraulic pump 9A may be directly changed by a mechanical mechanism in accordance with the operation of the speed change lever 13 and the speed setting dial 14.

Hereinafter, a specific operation example of the main shift control unit 22 and the speed control unit 23 and a flow example for controlling the traveling speed will be described with reference to FIG. 3 and FIG.

The main shift control unit 22 controls the angle of the swash plate of the hydraulic pump 9A of the continuously variable transmission 9 together with the speed control unit 23. First, the main shift control unit 22 receives the operation position of the shift lever 13 detected by the potentiometer 18 (step #1 in FIG. 4). The main shift control unit 22 holds swash plate angle data indicating a correspondence relation (correspondence relation of shift states) between an operation position of the shift lever 13 and a target angle of the swash plate of the hydraulic pump 9A of the continuously variable transmission 9.

The speed control unit 23 detects the set value of the speed setting dial 14 from the detection signal of the setting position of the speed setting dial 14 (step #2 in FIG. 4).

At this time, the speed control unit 23 determines from the detection signal of the setting position of the speed setting dial 14 whether the set value of the speed setting dial 14 has been changed (step #3 in FIG. 4). When the speed control unit 23 determines that the set value has been changed (step #3 Yes in FIG. 4 ), the operating position of the speed change lever 13 and the hydraulic pump of the continuously variable transmission 9 are determined based on the setting position of the speed setting dial 14. The swash plate angle data indicating the correspondence with the target angle of the swash plate of 9A is changed (step #4 in FIG. 4). Further, as described later in detail, the acceleration control unit 25 of the speed control unit 23 calculates the acceleration of the traveling speed from the current traveling speed to the changed traveling speed based on the set values before and after the change. Since the traveling speed corresponds to the angle of the swash plate of the hydraulic pump 9A, the acceleration of the traveling speed depends on the rate of change of the shift state (step #5 in FIG. 4).

Next, the acceleration control unit 25 determines whether or not the absolute value of the acceleration of the traveling speed is less than or equal to a predetermined upper limit value (step #6 in FIG. 4). When the absolute value of the acceleration of the traveling speed is larger than the predetermined upper limit value (No in step #6 of FIG. 4), the acceleration control unit 25 of the speed control unit 23 travels before the setting change with the acceleration of the upper limit value or less. The swash plate of the hydraulic pump 9A is controlled via the actuator 11 so that the speed is slowly changed to the traveling speed after the setting is changed. Specifically, the acceleration control unit 25 controls the swash plate angle change speed of the hydraulic pump 9A to the angle corresponding to the operation position of the speed change lever 13 and the setting position of the speed setting dial 14 (change rate of rotation speed/shift state). The actuator 11 is controlled so that () becomes gentle (step #7 in FIG. 4).

Further, after changing the correspondence, and when the absolute value of the acceleration of the traveling speed is less than or equal to a predetermined upper limit value (step #6 Yes in FIG. 4), and when it is determined that the set value is not changed (No in step #3 of FIG. 4), the main shift control unit 22 operates the actuator 11 based on the swash plate angle data, and the main shift control unit 22 does not change the angle corresponding to the operation position of the speed change lever 13 and the setting position of the speed setting dial 14. The swash plate of the hydraulic pump 9A of the stage transmission 9 is controlled (step #8 in FIG. 4).

In addition, when it is determined that the absolute value of the acceleration of the traveling speed is larger than the predetermined upper limit value, the acceleration control unit 25 uses the actuator 11 of the hydraulic pump 9A via the actuator 11 so that the change of the traveling speed becomes gentle. Control the swashplate. Specifically, the acceleration control unit 25 controls so that the rotation speed (rate of change in gear shift state) of the swash plate of the hydraulic pump 9A becomes gentle. The acceleration of the traveling speed depends on the rotation speed of the swash plate of the hydraulic pump 9A. Therefore, the rotation speed of the swash plate of the hydraulic pump 9A is controlled so that the absolute value of the acceleration of the traveling speed is equal to or less than the predetermined upper limit value. For example, the acceleration control unit 25 includes a low-pass filter (not shown), and when it is determined that the absolute value of the acceleration of the traveling speed is larger than a predetermined upper limit value, the unit time of the setting position of the speed setting dial 14 The operation amount (operation speed) per hit is transmitted to the actuator 11 via the low-pass filter. The low-pass filter can adjust the operation amount per unit time at the set position to be equal to or less than a predetermined operation amount. As a result, the operation amount of the setting position of the speed setting dial 14 can be transmitted to the actuator 11 at a speed equal to or lower than a predetermined operation speed, so that the rotation speed of the swash plate of the hydraulic pump 9A is suppressed and, as a result, the traveling speed is reduced. Acceleration can be suppressed.

Next, with reference to FIG. 3, a control configuration of the acceleration (rate of change of shift state) when the absolute value of acceleration (rate of change of shift state) is larger than the upper limit value will be described with reference to FIG.

First, the determination of acceleration will be described. The acceleration at which the traveling speed changes when the set value of the speed setting dial 14 is changed can be calculated from the traveling speed before the change, the traveling speed after the change, and the time required for changing the traveling speed. Then, the traveling speed before the change and the traveling speed after the change can be obtained by the operation position of the shift lever 13 and the set value of the speed setting dial 14 before and after the change. The time required for changing the traveling speed can be calculated from the performance of the continuously variable transmission 9. The speed control unit 23 calculates the acceleration from the traveling speed before and after the change and the time required to change the traveling speed, and determines whether the absolute value of the acceleration of the traveling speed is larger than a predetermined upper limit value. To do.

The acceleration when the traveling speed changes depends on the rotation speed and the rotation amount of the swash plate of the hydraulic pump 9A of the continuously variable transmission 9. When the operation position of the shift lever 13 is constant, the rotation speed and the rotation amount of the swash plate of the hydraulic pump 9A are determined by the change amount of the setting position of the speed setting dial 14 per unit time. Therefore, when the change amount (operation amount) of the set position of the speed setting dial 14 per unit time exceeds a predetermined amount, it is determined that the absolute value of the acceleration of the traveling speed is larger than a predetermined upper limit value. Is also good. Accordingly, it can be easily determined that the absolute value of the acceleration of the traveling speed is larger than the predetermined upper limit value.

Hereinafter, a change in traveling speed when the speed setting dial 14 is operated will be described. First, a change in the traveling speed when the acceleration (rate of change in shift state) relaxation control is not performed will be described. When the acceleration relaxation control is not performed, the traveling speed changes as illustrated in the speed transition graph 26 shown in FIG. In the example shown in the speed transition graph 26, when the set value of the speed setting dial 14 is changed from 100% to 50%, the traveling speed changes from V ₁₀₀ to V ₅₀ . The time for changing from V ₁₀₀ to V ₅₀ is t ₁ . The shorter the changing time t ₁ , the more rapidly the traveling speed changes. If the traveling speed changes abruptly, the driver may fall, it may be difficult to control the combine, various problems may occur in the cutting work, and various problems may occur, which is dangerous.

Next, a description will be given of changes in the traveling speed when the acceleration (rate of change in shift state) relaxation control is performed. When the acceleration is controlled, the traveling speed changes as illustrated in the speed transition graph 27 shown in FIG. In the example shown in the speed transition graph 27, when the set value of the speed setting dial 14 is changed from 100% to 50%, the traveling speed changes from V ₁₀₀ to V ₅₀ . Since the control for relaxing the acceleration is performed, the time for changing from V ₁₀₀ to V ₅₀ is t ₂ which is longer than t ₁ . Since the time t ₂ which changes from V ₁₀₀ to V ₅₀ is longer than the time t _1, when the control of the acceleration is performed, the change in travel speed becomes gentle than a case where the control of the acceleration is not performed. As a result, it is possible to prevent various problems such as the driver falling, the combine being difficult to control, and the cutting work having a problem.

In the above description, the case where the traveling speed is decelerated has been described, but similarly, when the traveling speed is increased, the acceleration control unit 25 also performs control to reduce the acceleration.

[Other Embodiment 1]
In the embodiment shown in FIG. 5, the change of the traveling speed from V ₁₀₀ to V ₅₀ is performed linearly and the acceleration during change is constant, but the acceleration during change is gradually increased. Alternatively, the change in traveling speed may be performed in a curved manner. For example, as illustrated in the speed transition graph 28 shown in FIG. 6, in the vicinity of V ₁₀₀ and V ₅₀ , which are the initial and end of the period in which the traveling speed changes, the traveling speed is gradually changed so that the traveling speed is gradually changed. The absolute value of acceleration is gradually changed according to the change of. As a result, the change in running speed is started smoothly, and the change in running speed is finished smoothly. As a result, the driver can be less likely to receive a shock due to a change in traveling speed, and smooth traveling can be performed. It is preferable to gradually increase the acceleration at least in the vicinity of V ₁₀₀ , which is the initial stage of the change in traveling speed. Since the driver is likely to receive a shock due to the change in the traveling speed at the moment when the change in the traveling speed is started, it is possible to smoothly drive the vehicle by reducing the shock at this time. Similar to the above-described embodiment, even when the traveling speed increases, the traveling speed is changed so that the traveling speed is gradually changed at least at the beginning and/or the end of the period in which the traveling speed changes. The absolute value of acceleration is gradually changed accordingly. Further, the upper limit value when the traveling speed is increased and the upper limit value when the traveling speed is decelerated can be made different. Further, it is preferable that the upper limit value when the traveling speed decelerates is smaller than the upper limit value when the traveling speed increases. The upper limit can be determined according to the magnitude of the shock felt by the driver, and the shock felt by the driver can be reduced by reducing the upper limit when the traveling speed is decelerated.

[Another embodiment 2]
The acceleration control is not limited to the configuration described in the above embodiment, and the acceleration of the traveling speed when the speed setting dial 14 is operated may be fixed. For example, the rotation speed (rate of change in gear shift state) of the swash plate of the hydraulic pump 9A such that the absolute value of the acceleration of the traveling speed is equal to or less than the predetermined upper limit value is selected in advance. Then, when the speed setting dial 14 is operated, the acceleration control unit 25 controls the swash plate of the hydraulic pump 9A to rotate at a preselected rotation speed regardless of the operation amount or the operation speed. Also good.

[Another embodiment 3]
In each of the above-described embodiments, the case has been described in which, when the absolute value of the acceleration of the traveling speed is larger than the predetermined upper limit value, control is performed to reduce the acceleration so that the absolute value of the acceleration becomes equal to or less than the upper limit value. On the other hand, the threshold value of the absolute value of the acceleration is set in advance, and when the absolute value of the acceleration of the traveling speed exceeds the predetermined threshold value, the absolute value of the acceleration becomes equal to or less than the upper limit value. You may perform control which relieves acceleration. By setting a threshold value separately from the upper limit value of the absolute value of acceleration, a threshold value with a margin is set, and if the absolute value of the acceleration of running speed exceeds the predetermined upper limit value, the acceleration Can be controlled. Therefore, the traveling speed can be gently changed more reliably.

Also, the threshold value can be made variable. By making the threshold variable, control is performed to moderate the acceleration at an appropriate threshold according to the running state, and the running speed can be more gently changed. In this case, the speed control unit 23 further includes a threshold value changing unit 23A that can arbitrarily set the threshold value.

[Other Embodiment 4]
A working vehicle such as a combine travels and operates the working vehicle using an engine 8 (hereinafter, see FIG. 3) as a power source. The engine 8 has a limit in operating temperature, and when it becomes higher than a predetermined temperature (abnormal temperature), it is necessary to stop the engine 8 or the like to cool the engine 8. Therefore, the work vehicle is generally provided with a function of issuing a warning when the temperature of the engine 8 rises to an abnormal temperature and constantly notifying the temperature of the engine 8. For example, in the work vehicle, when the temperature of the engine 8 exceeds 115° C. as an example of the abnormal temperature, a voice message prompting to stop the engine 8 or stop the work flows, or as shown in FIG. The high temperature warning lamp 30 indicating that the above is turned on has a warning function. Further, the work vehicle is provided with a water temperature gauge 31 on the display device 15, and the temperature of the cooling water of the engine 8 corresponding to the temperature of the engine 8 is constantly displayed on the water temperature gauge 31. The water thermometer 31 has, for example, a configuration in which seven liquid crystal lamps corresponding to the temperature of the cooling water of the engine 8 are lined up, and the respective liquid crystal lamps are sequentially turned on at the corresponding temperatures. When the temperature of the engine 8 (water temperature of the cooling water) exceeds 115° C., the water temperature gauge 31 indicates that the seventh liquid crystal lamp is turned on and the temperature of the engine 8 becomes an inappropriate temperature for the operator or the like. It is a structure that can be recognized.

When the operator or the like recognizes that the temperature of the engine 8 has become an abnormal temperature from the warning and the display of the water temperature gauge 31, the operation of the working machine such as the reaper 3 (see FIG. 1) and the traveling of the machine body are stopped. Alternatively, the engine 8 is stopped. At this time, when the warning is finished and the seventh liquid crystal lamp is turned off, the operator recognizes that the temperature of the engine 8 has dropped and starts the engine 8 or restarts the work. However, even if the temperature of the engine 8 falls below 115° C., if the temperature is not sufficiently lowered, the temperature of the engine 8 may exceed 115° C. immediately after restarting the work. Therefore, it may be possible to restart and stop the work in a short time.

In order to avoid such a situation, when the water temperature of the cooling water tends to decrease, the water temperature gauge 31 of the present embodiment delays turning off the liquid crystal lamp corresponding to the temperature. Specifically, the seventh liquid crystal lamp corresponding to the abnormal temperature of 115° C. or higher does not turn off immediately even if the water temperature becomes lower than 115° C., and delays the turning off. Other liquid crystal lamps may also be turned off when the temperature becomes lower than the corresponding temperature. For example, when the water temperature tends to rise, the liquid crystal lamp turns on the liquid crystal lamp in response to the actual water temperature, and when the water temperature tends to fall, the actual water temperature falls below the corresponding water temperature by a predetermined temperature. The liquid crystal lamp is turned off for the first time. Alternatively, when the water temperature tends to rise, the liquid crystal lamp lights up the liquid crystal lamp in real time in response to the actual water temperature, and when the water temperature tends to fall, the water temperature drops to the corresponding water temperature, and then the predetermined temperature is reached. Turn off the liquid crystal lamp after a lapse of time. At this time, the water temperature gauge 31 is equipped with a low-pass filter (not shown), and only when the water temperature tends to decrease, the measured water temperature is peak-held using the low-pass filter and the timing of turning off the liquid crystal lamp is delayed. Let

As described above, when the temperature of the cooling water tends to decrease, by delaying the turning off of the liquid crystal lamp corresponding to the temperature, the operator can operate the work machine before the temperature of the engine 8 is sufficiently decreased. It is possible to suppress resumption of work and traveling.

[Other Embodiment 5]
Arrangement positions and shapes of the display device 15 and the speed setting dial 14 are not limited to the above-mentioned configurations.

[Another embodiment 6]
The gear shift operation tool is not limited to the lever type operation tool such as the above-described gear shift lever 13.

INDUSTRIAL APPLICABILITY The present invention can be used for various work vehicles such as self-draining combine harvesters and ordinary combine harvesters that can run.

1 Traveling device 8 Engine (power source)
9 Continuously variable transmission (transmission)
13 Shift lever (shift operation tool)
14 Speed setting dial (correspondence setting tool)
25 Acceleration control unit (change rate control unit)

Claims (6)

A gear shift operation tool that is operated within a certain operation range to change the traveling speed,
A transmission that shifts power from a power source and transmits the power to a traveling device, and that is changed to a shift state according to an operation position of the shift operating tool by operating the shift operating tool,
A correspondence relation setting tool for changing the correspondence relation between the operation position and the shift state,
A work vehicle comprising: a change rate control unit that controls the change rate of the shift state within a range equal to or less than a predetermined upper limit value when the correspondence relationship setting tool is operated. The rate of change control unit controls the rate of change within the range of the upper limit value or less when the rate of change exceeds a predetermined threshold value,
The work vehicle according to claim 1, further comprising a threshold value changing unit that changes the threshold value. The work according to claim 1 or 2, wherein the change rate control unit controls the change rate within the range of the upper limit value or less when the operation amount of the correspondence relationship setting tool per unit time is a predetermined value or more. car. The work vehicle according to claim 1, wherein the change rate control unit gradually increases the change rate. The work vehicle according to any one of claims 1 to 4, wherein the upper limit value is different during acceleration and during deceleration. The work vehicle according to claim 5, wherein the upper limit value during acceleration is larger than the upper limit value during deceleration.

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