JP2006342840A - Load controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control work load on an engine during work to make it proper load and make running speed or rotational speed of the engine substantially constant. <P>SOLUTION: A PTO clutch 38 is arranged between an output shaft and a PTO shaft 11 of the engine 4. A means for connecting and disconnecting the PTO clutch 38, a means for detecting running speed, a means for detecting rotational speed of the engine, an engine rotational speed setting means, and a gear shift change means are connected with a controller 20 as a control means. When the PTO clutch connecting and disconnecting means is turned ON, running speed is changed for fluctuation of load to keep rotational speed of the engine substantially constant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for controlling an engine speed and a traveling speed in accordance with a work load when a work vehicle, particularly an agricultural work vehicle, is operated with and without a PTO output.

  Conventionally, when working with a rotary tiller, if the soil in the field becomes hard or deeply tilled, the load increases and the engine speed decreases, and if the engine load increases further, it stops. . If the engine stops, the work cannot be continued and the finish is also deteriorated. Therefore, usually, the vehicle speed of the tractor is reduced or the rotary is lifted to reduce the load (for example, patent document). 1).

Further, in recent years, a work panel such as a tractor is provided with a meter panel as a liquid crystal display unit, and various state displays and setting changes are performed on the meter panel (for example, Patent Document 2 or Patent Document). 3). In this type of work vehicle, an operation tool such as a screen operation switch is provided in the vicinity of the meter panel, and state display switching and setting change are performed in accordance with the operation.
JP-A-7-132754 JP 2001-301488 A JP 2004-161094 A

  However, when the rotary is lifted with respect to an increase in load, the working depth changes and the working accuracy deteriorates. Further, in the technique of Patent Document 1, when a large resistance is generated during work, the traveling speed is automatically decelerated based on the magnitude of the load, and the engine rotational speed is also decreased as the traveling speed decreases. Thus, the PTO rotational speed is also reduced. However, since the reduction in the engine rotational speed leads to a reduction in torque, the running performance is lowered and the workability is lowered. In a tilling operation such as a rotary, the finish is more beautiful when the rotation speed is constant, and uniform crushed soil characteristics are obtained. On the other hand, in traction work or the like that does not require power from the PTO shaft, such as plow work, the finish is more beautiful and the work accuracy is improved by keeping the traveling speed constant.

  In addition, when displaying the type of work, working depth, gear position, traveling speed, rotation speed, etc. on the liquid crystal panel etc. provided in the conventional meter panel, other types of display are impossible at once, A display changeover switch for changing the display is provided in the vicinity of the meter panel (the handle column or a position in the vicinity thereof). When the display screen is changed during work, the operator in the driver's seat is temporarily In addition, the user has to move his hand from the handle to the display changeover switch and move the line of sight, which may cause the direction of travel to bend.

  In order to solve the above problems, the present invention proposes a load control device that controls the running speed or engine speed to be substantially constant so that the work load on the engine becomes an appropriate load during work. .

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

  That is, in claim 1, a PTO clutch is arranged between the engine output shaft and the PTO shaft, the PTO clutch can be connected and disconnected, the traveling speed detecting means, and the engine speed. When the detecting means, the engine speed setting means, the shift changing means, etc. are connected to the controller as the control means, and the PTO clutch connecting / disconnecting means is turned on, the traveling speed is changed with respect to the load fluctuation. Thus, the engine speed is controlled to be substantially constant.

  According to a second aspect of the present invention, a PTO clutch is disposed between the engine output shaft and the PTO shaft so that the PTO clutch can be connected and disconnected, a means for detecting the running speed, and the rotational speed of the engine output shaft. Is connected to a controller as a control means, and when the PTO clutch connecting / disconnecting means is turned off, the engine speed is detected with respect to load fluctuations. It is changed and controlled to keep the traveling speed substantially constant.

  According to a third aspect of the present invention, there is provided means for changing the speed ratio and displaying that the speed is being increased or decreased when the traveling speed is increasing or decreasing.

  According to a fourth aspect of the present invention, ON / OFF of the PTO clutch connection / disconnection is displayed on a meter panel disposed in front of the driver's seat, and the display is switched by a display switching member provided on an operation lever disposed in the vicinity of the driver's seat. It is configured to be possible.

  As effects of the present invention, the following effects can be obtained.

  By controlling as in claim 1, during the operation of driving the PTO shaft, the engine rotation is controlled to be constant even when the load is increased, so that the rotation of the PTO shaft is also constant and high accuracy is achieved. Work will be obtained.

  By performing the control as in claim 2, when the operation does not drive the PTO shaft, the control is performed so that the traveling speed is constant even when the load is increased, so that almost no change in the finish in the towing operation or the like occurs. As a result, work with high accuracy can be obtained.

By configuring as in the third aspect, the operator can recognize the load state, so that the traveling speed and the engine speed can be easily set appropriately in advance. For example, when the vehicle is decelerating due to load control, a message such as “Decelerating” is displayed on the display panel to notify that the speed is automatically changed from the speed set by the main shift lever.
In addition, it is possible to prepare for the traveling speed returning to the speed set by the main shift lever when the load control mode is released.

  By configuring as in claim 4, it can be easily determined whether or not it is during load control, and when it is desired to know other information, the display can be easily changed and recognized.

Next, embodiments of the invention will be described.
1 is a side view showing an overall configuration of a tractor according to an embodiment of the present invention, FIG. 2 is a block diagram of a traveling control system, and FIG. 3 is a load of the present invention including a case where a PTO switch is ON. FIG. 4 is a flowchart showing an example of a series of processing performed by the control device, FIG. 4 is a flowchart showing an example of a series of processing performed by the load control device of the present invention when the PTO switch is OFF, and FIG. FIG. 6 is an explanatory diagram showing the state of switching information to be displayed on the display panel, (a) displaying traveling speed information, (b) displaying PTO shaft rotational speed information, and FIG. FIG. 8 is an explanatory diagram in which the display switching member according to the present invention is provided in the grip portion of the main transmission lever, FIG. 8 is an explanatory diagram in which the display switching member according to the present invention is provided in the grip portion of the position lever, and FIG. Insert the member into the position lever. Parts is an explanatory diagram provided near.

The overall configuration of the tractor 1 according to one embodiment of the present invention will be described with reference to FIG.
Front wheels 2 and 2 and rear wheels 3 and 3 are respectively arranged on the front and rear of the vehicle body of the tractor 1, a bonnet 8 incorporating the engine 4 is disposed at the front of the vehicle body, and a cabin 5 is disposed at the rear of the vehicle body. .
A steering handle 6 is provided in the cabin 5, and a driver seat 7 is provided behind the steering handle 6.
A clutch housing 9 is disposed behind the engine 4, and a transmission case (hereinafter referred to as a transmission case) 10 is connected to the rear of the clutch housing 9 to transmit power from the engine 4 to the rear wheel 3 for driving.
The driving force of the engine 4 is transmitted to a PTO shaft (power take-off shaft) 11 protruding from the rear end of the transmission case 10, and a universal joint is connected to the rear end of the aircraft by the rotation of the PTO shaft 11. And a working machine (not shown) connected via a transmission shaft or the like. However, the PTO shaft 11 can protrude forward of the machine body, or can protrude between the front wheel 2 and the rear wheel 3, and the arrangement position of the PTO shaft 11 is not limited.
The rotational power input to the mission case 10 is branched into two systems of traveling driving force for driving the front wheels 2 and 2 and the rear wheels 3 and 3 and PTO driving force for external power extraction.

FIG. 2 is a block diagram of the travel control system.
The steering section in the cabin 5 is switched to control whether the accelerator pedal 21 and the accelerator lever 22 serving as means for manually setting the rotation speed of the engine 4 and the work load on the engine 4 are controlled (load control mode) or not. A main speed change lever 25, a sub speed change lever, a position lever 26, a PTO speed change lever and the like are disposed on a mode changeover switch 23 and a fender 27 provided on the side of the driver's seat 7, and the accelerator pedal 21 and the accelerator The rotation amount of the lever 22 is detected by a rotation amount detection means 28 such as a potentiometer, and the rotation amount detection means 28 is connected to the engine controller 36. However, the rotation amount detection means 28 may be connected to the controller 20 so that the engine controller 36 and the controller 20 exchange information by communication or the like.
A meter panel 29 in which a tachometer, an alarm monitor, a liquid crystal panel, and the like are arranged in front of the driver seat 7 is provided with a display panel 30 composed of liquid crystal or the like. Is configured to be capable of switching and displaying information such as travel speed, work (travel) time, PTO shaft rotation speed, shift position, fuel gauge, water temperature gauge, and the like.

  Power is transmitted from the output shaft of the engine 4 into the mission case 10 via a clutch (or damper). In the transmission case 10, power is branched from the input shaft to the traveling system and the PTO system. The traveling system transmits power to the rear wheels and the front wheels via the traveling main transmission and the traveling auxiliary transmission. Power is transmitted to the PTO shaft 11 via the PTO clutch 38 and the PTO transmission. However, it is also possible to cancel the transmission of power at the neutral position of the PTO transmission without the PTO clutch 38.

  The PTO clutch 38 is constituted by an electromagnetic clutch, and the PTO clutch 38 can be connected to and disconnected from the operation of the PTO switch 33 so that the driving of the PTO shaft 11 can be interrupted. The PTO switch 33 is connected to the PTO clutch 38 via the controller 20. However, instead of detecting ON / OFF of the PTO switch 33, it is possible to detect the shift position or neutral position of the PTO shift lever. Further, the PTO clutch 38 can be constituted by a multi-plate type or the like, and is not limited.

  An engine speed sensor 34 that is a means for detecting the rotational speed is disposed on the crankshaft (output shaft) of the engine 4, and the detected value of the engine speed sensor 34 is input to the engine controller 36. On the other hand, the rotation of the engine can be set by an engine speed setting means such as an accelerator lever 22 or an accelerator pedal 21, and the setting position of the engine speed setting means is detected by a rotation amount detection means 28 constituted by an angle sensor or the like. Input to the controller 36. Whether or not a load is applied to the engine 4 is determined by the load detection means of the controller 20 or the engine controller 36 based on changes in the engine speed, the rack position, and the like.

The controller 20 is connected to an engine controller 36 that controls the rotation by changing the rack position, fuel injection amount, injection timing, and the like of the engine 4 so that the rotation speed can be changed according to the load, the set traveling speed, and the like. I am doing so.
Further, the controller 20 is connected to a traveling speed sensor 35, a traveling speed setting means, and a speed change means 24 provided on the axle of the front wheels or the rear wheels, and controls so that the traveling speed can travel at the set speed. . The speed change speed setting means is a main speed change lever 25 or a sub speed change lever. The speed change position is detected by a travel speed setting position detection means 37 constituted by an angle sensor or the like provided at the lever base and connected to the controller 20. The detection value is entered. The speed change means 24 is composed of an actuator such as a motor or a cylinder, and is operated by a signal from the controller 20 to change the speed change means 24. The travel speed control when a load is applied will be described later.

  Thus, two types of load control are performed when the PTO switch 33 is ON (PTO clutch engagement) and OFF (PTO clutch disengagement). That is, when the PTO switch 33 is ON, the controller 20 keeps the traveling speed within a certain range (for example, about 110% to 50%) with respect to the set speed so that the engine rotation is kept substantially constant with respect to the work load. Control automatically. On the other hand, when the PTO switch 33 is OFF, the engine speed is automatically controlled so as to keep the traveling speed substantially constant with respect to the work load. These control states are displayed on the display panel 30 of the meter panel 29. That is, the set speed, travel speed, shift position, speed increasing / decelerating speed, rotation speed, etc. are displayed on the display panel 30 of the meter panel 29 so that the operator can easily check the state.

Next, the load control device according to the present invention will be described based on the flowchart of FIG. 3 showing an example of a series of processes performed by the load control device.
Generally, since the hardness of the field is not uniform, the work load fluctuates during tillage work or plow work, and the rotational speed of the engine 4 also fluctuates according to the load fluctuation. Since the running speed also fluctuates due to fluctuations in the engine speed, the finish becomes worse. Therefore, the present invention is configured to perform more accurate work by performing load control separately in the case of working by driving the PTO shaft 11 and the work not driving the PTO shaft 11.

  First, when starting work, an operator determines whether or not to perform load control according to the type of work, and turns the mode switch 23 ON / OFF. The controller 20 determines whether or not the load control mode is in effect according to whether the mode switch 23 is ON or OFF (S10). In other words, the mode changeover switch 23 is turned on and the mode changeover switch 23 is turned on later when the engine speed is to be kept constant when the load fluctuates, such as tillage work, plow work, harvesting work, lawn mowing work or the like. To improve the work accuracy. Also, PTO shafts such as grass collection work, loader work, snow removal work, etc. where load fluctuation is small, work accuracy is relatively not required even when load fluctuation occurs, load control is not required, or spraying work etc. In an operation or the like for which the rotation of the (engine) and the traveling speed are desired to be proportional, the mode changeover switch 23 is turned OFF and the operation is not performed. At this time, the display panel 30 of the meter panel 29 displays whether or not it is in the load control mode. When load control is not performed, the engine controller 36 controls the rack position of the fuel injection pump so that the rotation speed set by the accelerator lever 22 or the accelerator pedal 21 is obtained.

Next, in the load control mode, it is determined whether the PTO switch 33 is ON or OFF. (S20).
If it is determined in step S20 that the PTO switch 33 is ON, the process of the load control device proceeds to step S30. On the other hand, if it is determined that the PTO switch 33 is OFF, the process proceeds to step S100. Transition.

When the PTO switch 33 is ON, the PTO clutch 38 is set to “contact”, power is transmitted from the output shaft of the engine 4 to the PTO shaft 11 via the PTO clutch 38, and the work machine is driven while driving to work. Do. In this operation, it is determined whether or not the load is larger than the set large load value by the load detection means (S30), and when it is determined that the work load is large, the controller 20 drives the shift change means 24. Thus, the traveling speed ratio is decreased according to the size of the work load to decelerate. The speed ratio is a variable that is proportional to the traveling speed and inversely proportional to the engine speed. Further, the shift changing means 24 controls the transmission, and is a means for changing the swash plate of the HST, for example.
In this way, when the set speed ratio is reduced, that is, when the speed ratio set by the operator with the main speed change lever 25 is set to 100%, control is performed so as to reduce the load further and reduce the load on the engine 4.

Then, the traveling speed ratio (actual speed ratio) is compared with the set speed ratio, that is, the controller 20 calculates the ratio of the traveling speed sensor 35 to the traveling speed setting position detecting means 37 and sets the ratio X% ( For example, it is determined whether or not the vehicle is decelerated to 50% or less, that is, the traveling speed ratio is equal to or less than half of the set speed ratio (S40).
Here, “X%” is the ratio of the lowest traveling speed ratio that can permit deceleration with respect to the set speed ratio.
If it is determined in step S40 that the traveling speed ratio has decreased to a certain ratio X% (for example, 50%) or less of the set speed ratio, the deceleration is stopped and the current speed ratio is maintained (S41).
On the other hand, when it is determined in step S40 that the traveling speed ratio has not reached the predetermined ratio X% or less of the set speed ratio, a deceleration operation is performed (S42).

If it is determined in step S30 that the work load on the engine 4 is not greater than the set large load value, the controller 20 determines whether the work load is smaller than the set small load value (S50). In other words, if it is larger than the set large load value, it is necessary to decrease the traveling speed and increase the engine speed, and if it is smaller than the set small load value, there is a margin to increase the traveling speed, If the load value is between the value and the set small load value, it is determined that it is not necessary to increase or decrease the speed as an appropriate load, and the set rotational speed can be maintained.
When the work load is smaller than the set small load value, the controller 20 drives the shift changing means 24 to automatically increase the traveling speed ratio to be equal to or higher than the set speed ratio.
By configuring as described above, the rotational speed of the engine 4 with respect to the fluctuation of the work load can be kept substantially constant. By keeping the engine rotational speed substantially constant, the rotational speed of the PTO also becomes substantially constant, and high-precision work can be performed.

Then, the traveling speed ratio is compared with the set speed ratio to determine whether or not the traveling speed ratio has increased to a certain ratio Y% (for example, 110%) of the set speed ratio (S60).
Here, “Y%” is the ratio of the speed ratio at which the maximum speed can be increased when the load is light.
If it is determined in step S60 that the traveling speed ratio has increased to a certain ratio Y% (for example, 110%) or more of the set speed ratio, the speed increase is stopped and the current speed ratio is maintained (S61).
If it is determined in step S60 that the traveling speed has not increased to a certain ratio Y% or more of the set speed, a speed increasing operation is performed (S62).

  If it is determined in step S50 that the work load on the engine 4 is neither large nor small, the current speed ratio is maintained (S55).

  Thus, in step S70, the controller 20 compares the traveling speed ratio with the set speed ratio to determine whether the traveling speed ratio is smaller than the set speed ratio (S70). If it is smaller than the set speed ratio, since the load is large and the vehicle is traveling at a speed lower than the set speed, it is displayed on the display panel 30 that it is “decelerating” (S75). Or you may display by the "deceleration ratio" how much specifically this deceleration state is decelerating.

  If it is determined in step S70 that the current speed ratio is not smaller than the set speed ratio, the controller 20 determines whether the travel speed ratio is greater than the set speed ratio (S80). If the speed is higher than the set speed ratio, since the load is small and the vehicle is traveling at a speed higher than the set speed, it is displayed on the display panel 30 that the speed is being increased (S85). Alternatively, the “speed increase ratio” indicating how much the speed increase state is specifically increased may be displayed.

Next, the load control device in a state where the PTO switch 33 is OFF will be described below with reference to FIG.
If it is determined in step 20 that the PTO switch 33 is in the OFF state, the traveling speed is required to be constant because it is a towing operation or the like that is not output from the PTO shaft 11. During this work, it is determined whether or not the work load is larger than a preset upper limit load set value (S100).

If it is determined in step S100 that the work load is greater than the upper limit load set value, the rotation amount detection means 28 determines whether the engine speed is equal to or less than the set maximum speed (S110).
If it is determined that the engine speed is equal to or less than the set maximum speed, the process proceeds to step S115. On the other hand, if it is determined that the engine speed is not equal to or less than the set maximum speed, the process proceeds to step S140 described later. .

If the engine speed set by the accelerator pedal 21 or the accelerator lever 22 is less than the maximum speed when the load increases, there is room to increase the engine speed, so the engine 4 speed is automatically increased. Then, the torque is increased, and the speed ratio is decreased so as not to increase more than the set speed (S115).
In other words, if the engine speed decreases and the traveling speed decreases due to an increase in load, the engine controller 36 increases the engine speed and reduces the speed ratio. That is, when only the engine speed is increased, the traveling speed is also increased. Therefore, the speed ratio is lowered so that the traveling speed is maintained substantially constant with respect to the fluctuation of the work load. Thus, high-precision work can be performed by keeping the traveling speed substantially constant.

  If it is determined in step S100 that the work load on the engine 4 is not large, it is determined whether the work load is smaller than a set value (S120). In the determination in step S120, when the work load is larger than the lower limit set value, the engine speed is not changed so as to maintain this state as an appropriate load.

In the determination of step S120, if the work load is smaller than the lower limit setting value, the engine speed can be maintained even if the engine speed is decreased, so that the engine speed can be maintained, so the engine speed is decreased. The engine speed is kept higher than the lower limit (Zrpm) of the engine speed set in advance so as to keep the speed. That is, when the load is small, it is determined whether or not the detected value from the engine speed sensor 34 is larger than the lower limit value Z of the engine speed (S130).
When it is determined that the rotational speed of the engine 4 is equal to or higher than Zrpm, the rotational speed of the engine 4 is decreased, and the speed ratio is increased to maintain the set speed (S135).
In this way, if only the engine speed is decreased with respect to the decrease in the work load, the traveling speed becomes slow, so the speed ratio is also increased and the traveling speed is kept substantially constant. By keeping the running speed substantially constant, high-precision work can be performed. In particular, when the load is low, the engine speed can be reduced and the work can be performed, thereby reducing fuel consumption and reducing noise. Therefore, worker fatigue can be reduced.
When it is determined that the rotational speed of the engine 4 is less than Zrpm, the engine rotational speed is not changed.

  When the process proceeds to step S140, the controller 20 determines whether or not the engine speed of the engine 4 is equal to the set engine speed (S140). If it is determined that the rotational speed of the engine 4 is not the same as the engine rotational speed set by the accelerator pedal 21 or the accelerator lever 22, the rotational speed of the engine 4 is being changed by the engine controller 36. It is displayed on the panel 30 that “the engine speed is being changed” (S145).

  In this way, since the load state can be recognized by the operator by displaying the increase or decrease of the traveling speed or the engine speed by the load control on the display panel 30, the traveling speed and the engine speed are easily and appropriately set in advance. be able to. For example, when the vehicle is decelerating by load control, “decelerated” or the like is displayed on the display panel 30 to notify the operator that the speed is automatically changed from the speed set by the main transmission lever 25.

  Next, the display switching member according to the present invention will be described with reference to FIGS.

As shown in FIG. 5, the tractor 1 according to this embodiment includes a meter panel 29 in front of the driver seat 7 in the cabin 5, and the driver seat 7 has a main transmission lever 25, a position lever 26 and the like laterally. It has.
The meter panel 29 is provided with a display panel 30 composed of a tachometer, an alarm monitor, a lamp that raises the back and the working machine, a liquid crystal, and the like. The display panel 30 includes a running speed, a running time, In addition to the PTO shaft rotation speed, shift position, fuel, and water temperature, information that informs or alerts the user of seat belt attachment, hydraulic pressure abnormality, electrical system abnormality, etc. can be displayed.
As a means for switching the display information on the display panel 30, the conventional display switching member is provided near the meter panel 29 (the handle column or a position in the vicinity thereof), so that the worker sitting on the driver's seat 7 is working. Looking at the front, the operator holds the steering handle 6 or the main speed change lever 25 or the position lever 26, and when switching the display screen during work, the operator temporarily turns the steering handle 6 or the main speed change lever 25 or You have to release your hand from the position lever 26 and move your hand to the display switching member provided in the vicinity of the meter panel 29 and search for it by hand.

Therefore, the present invention has a configuration in which the display switching member 40 is provided in the vicinity of the lever or the base portion of the lever, which is usually placed during work, in order to solve the above problems.
In this embodiment, information such as travel speed, travel (work) time, and PTO shaft rotation speed can be displayed on the display panel 30. The information displayed on the display panel 30 is switched and displayed step by step by pushing the display switching member 40 step by step. An example is shown in FIGS. 6 (a) and 6 (b).
It is also possible to configure the information to be displayed on the display panel 30 according to the length of time for which the display switching member 40 is pressed. That is, when the display switching member 40 is not pressed, that is, when the display information in the normal state is the traveling speed, the display information is switched to the travel time information by pressing the display switching member 40 briefly. By pressing the display switching member 40 for a long time, the display switching member 40 is set to display the information on the PTO shaft rotational speed.
Further, in this embodiment, the display switching member 40 is constituted by a switch. However, the display switching member 40 is constituted by a dial, and information to be displayed on the display panel 30 is set in advance on a dial meter provided stepwise. It is also possible to configure so that the display can be switched by switching the dial in stages.

Next, a first embodiment of the display switching member 40b according to the present invention will be described with reference to FIG.
As shown in FIG. 7, a display switching member 40b for switching display information on the display panel 30 of the meter panel 29 is provided in the grip portion of the main transmission lever 25 for performing a shifting operation.
Specifically, the display switching member 40b is provided on the side surface, the back surface, or the front surface of the grip portion of the main speed change lever 25, and the operator sitting on the driver's seat 7 holds the grip portion of the main speed change lever 25. The display switching member 40b is provided at a position where the (for example, thumb) hits.
With this configuration, the operator can change the display on the display panel 30 by pressing the display switching member 40b while performing a shift operation with the main shift lever 25 during work and looking forward while traveling. Work can be done efficiently.

Next, a second embodiment of the display switching member 40c according to the present invention will be described with reference to FIG.
As shown in FIG. 8, it is also possible to provide a display switching member 40c for switching display information on the display panel 30 of the meter panel 29 on the side, back or front of the grip portion of the position lever 26. The configuration in which the display switching member 40c is provided on the position lever 26 is the same as in the first embodiment. When an operator sitting on the driver's seat 7 grips the grip portion of the position lever 26, the finger (for example, thumb) hits. The display switching member 40b is provided at the position. With this configuration, the display information on the display panel 30 can be switched while the work implement is operated as described above.

Next, a third embodiment of the display switching member 40d according to the present invention will be described with reference to FIG.
In the present embodiment, it is also possible to provide a display switching member 40d for switching display information on the display panel 30 of the meter panel 29 in the vicinity of the base portion of the main transmission lever 25 or the position lever 26. That is, the display switching member 40 d is provided on the upper surface of the fender 27. In FIG. 9, the display switching member 40 d is arranged near the base of the position lever 26.
With this configuration, the amount of movement of the hand with respect to the conventional position is small, so that efficient work can be performed.
However, as shown in FIG. 5, a conventional display switching member 40a can be provided in the vicinity of the meter panel 29 (the handle column or a position in the vicinity thereof).

The side view which showed the whole structure of the tractor which concerns on one Example of this invention. The block diagram of a traveling control system. The flowchart which showed an example of a series of processes which the load control apparatus of this invention performs also including the case where a PTO switch is ON. The flowchart which showed an example of a series of processes which the load control apparatus of this invention performs when a PTO switch is OFF. The top view in the cabin of a tractor. It is explanatory drawing of the mode which switched the information displayed on a display panel, (a) displays the information of traveling speed, (b) displays the information of PTO shaft rotation speed. Explanatory drawing which provided the display switching member which concerns on this invention in the grip part of the main transmission lever. Explanatory drawing which provided the display switching member which concerns on this invention in the grip part of the position lever. Explanatory drawing which provided the display switching member which concerns on this invention in the base part vicinity of the position lever.

Explanation of symbols

4 Engine 11 PTO Shaft 20 Controller 21 Accelerator Pedal 22 Accelerator Lever 23 Mode Changeover Switch 24 Shift Change Means 25 Main Shift Lever 26 Position Lever 27 Fender 28 Rotation Amount Detection Means 29 Meter Panel 30 Display Panel 33 PTO Switch 34 Engine Speed Sensor 35 Travel speed sensor 36 Engine controller 37 Travel speed setting position detection means 40, 40a, 40b, 40c, 40d Display switching member

Claims (4)

  A means for disposing a PTO clutch between an engine output shaft and a PTO shaft so that the PTO clutch can be connected / disconnected, a means for detecting a running speed, a means for detecting the engine speed, and an engine speed When setting means and shift changing means are connected to a controller as control means and the PTO clutch connecting / disconnecting means is turned ON, the speed ratio is changed with respect to load fluctuations, and the engine speed is substantially constant. A load control device that is controlled to maintain   A means for disposing a PTO clutch between an engine output shaft and a PTO shaft so that the PTO clutch can be connected / disconnected, a means for detecting a running speed, a means for detecting the engine speed, and an engine speed When the setting means and the speed change means are connected to the controller as the control means and the PTO clutch connecting / disconnecting means is turned OFF, the engine speed and speed ratio are changed with respect to load fluctuations, and the running speed Is controlled so as to be kept substantially constant.   3. The apparatus according to claim 1, further comprising means for displaying that the speed ratio is changed and the traveling speed is increasing or decreasing when the traveling speed is increasing or decelerating. The load control device described in 1.   ON / OFF of the PTO clutch connection / disconnection is displayed on a meter panel arranged in front of the driver's seat, and the display is configured to be switchable by a display switching member provided on an operation lever arranged in the vicinity of the driver's seat. The load control device according to any one of claims 1 to 3, wherein the load control device is characterized.

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