JP6985465B2 - Work vehicle - Google Patents

Description

The present invention relates to a work vehicle technique.

Conventionally, in work vehicles such as tractors, those that transmit the rotational power of an engine to a traveling device via a stepless speed changer have been known. The work vehicle includes an accelerator lever and an accelerator pedal, which are engine rotation speed setting means for setting the engine rotation speed at normal times.
Further, a work vehicle that changes the vehicle speed according to an engine load represented by an engine load factor, an engine down amount, a traction torque, or the like during work is also known. When the engine load is heavy (during heavy load), the vehicle speed is slowed down to prevent engine stall. Further, when the engine load is small (when the load is light), the vehicle speed is increased and the running performance is improved.

Japanese Unexamined Patent Publication No. 2007-315472

However, when the vehicle speed is increased under a light load, the running performance is improved, but the engine speed is also increased more than necessary, so that the fuel efficiency cannot be improved.

Therefore, in view of the above problems, it is an object of the present invention to provide a work vehicle capable of traveling with low fuel consumption and improving work efficiency at the time of a light load.

The problem to be solved by the present invention is as described above, and next, the means for solving this problem will be described.

In claim 1, a control device that controls the engine speed and the vehicle speed, and an engine speed change amount setting means that can set an allowable amount of the engine speed to be reduced from the engine speed set by the accelerator lever. Provided, the control device performs control to reduce the engine speed within the allowable amount while maintaining the vehicle speed constant when the load of the engine is lighter than a predetermined load value. , A work vehicle that temporarily suspends the execution of the control based on the operation of the accelerator pedal.

As the effect of the present invention, the following effects are exhibited.

According to the present invention, when the load is light, the work vehicle can be driven with low fuel consumption by reducing the engine speed while maintaining the vehicle speed constant. Also, prevent stalling,
It is possible to improve the work efficiency of the work vehicle.

The whole side view of the tractor which concerns on one Embodiment of this invention. The figure which shows the power transmission structure of a tractor. The block diagram which shows the structure which concerns on the control of a tractor. Top view showing the operation panel. A plan view showing a display unit. The first flowchart which shows the control mode of engine speed and vehicle speed control. The second flowchart which shows the control mode of engine speed and vehicle speed control. The third flowchart which shows the control mode of engine speed and vehicle speed control. The fourth flowchart which shows the control mode of engine speed and vehicle speed control. FIG. 5 is a fifth flowchart showing a control mode of engine speed and vehicle speed control. The graph which shows the relationship between a load, an engine speed and a vehicle speed and a time. The graph which shows the relationship between the engine speed and time when the engine speed upper limit value is changed. The graph which shows the relationship between the engine speed and time when the target engine speed is changed.

Next, the overall configuration of the tractor 1 according to the embodiment of the present invention will be described.

As shown in FIG. 1, in the tractor 1, the airframe frame 2 is arranged with the longitudinal direction as the front-rear direction, and is supported by a pair of left and right front wheels 3.3 at the front portion thereof via a front axle, and at the rear portion thereof. It is supported by a pair of left and right rear wheels 4 and 4 via the rear axle. An engine 5 is provided at the front of the fuselage frame 2 and is covered with a bonnet 6. A mission case 7 for accommodating a part of the power transmission mechanism of the tractor 1 is provided at the rear of the machine frame 2.

A cabin 8 is arranged behind the bonnet 6, and a driving operation unit 10 for an operator to board and operate the tractor 1 is provided inside the cabin 8. In the driving operation unit 10, the steering wheel 11 is provided in the front portion, and the seat 12 is arranged behind the steering wheel 11. Further, on the side portion of the seat 12, a gear ratio setting means 63, a position lever (or position switch) serving as an elevating position setting means 72, a tillage depth setting means 65, etc. are arranged, and a handle column side portion of the steering handle 11 is arranged. An accelerator lever and a forward / backward switching lever 62, which serve as engine speed setting means 70, are arranged in the vehicle (see FIG. 3). An accelerator pedal (engine speed setting means 70), a brake pedal, a main clutch pedal, a diff lock pedal, and the like are arranged on the step below the front of the seat 12.

The work equipment connecting device 20 mainly includes a top link 21, a lower link 22/22, and a lift rod 23/23. The top link 21 is rotatably connected to a top link bracket fixed to the rear of the mission case 7. The lower links 22 and 22 are rotatably connected to both sides of the mission case 7 or the rear axle housing. Lift rod 23
One end of the 23 is rotatably connected to the front and rear halfway portions of the lower links 22 and 22, and the other end is rotatably connected to the lift arms 24 and 24 protruding rearward from the hydraulic case. A position sensor serving as an elevating position detecting means 73 is arranged at the rotation base of the lift arm 24. A rotary tiller 30 is connected to the rear ends of the top link 21 and the lower links 22 and 22 as a working machine in the present embodiment. However, the working machine is not limited to the rotary tilling device 30, and a chemical sprayer, a mower, a rake, or the like can be attached.

The rotary tillage device 30 includes a tillage claw 31, a tillage cover 32, a rear cover 33, a chain case 34, and the like. Tillage claws 31 and 31 ... are claw shafts 35 laid horizontally so as to be rotatable in the left-right direction.
It is planted radially at appropriate intervals on the top, and the rotation locus 3 of the tip of the tilling claws 31.31 ...
The tillage cover 32 is arranged so as to cover the upper side and the side surface of 6. The front end of the rear cover 33 is rotatably connected to the rear end of the tillage cover 32, and the rotation of the rear cover 33 is detected by the cover angle sensor serving as the tillage depth detecting means 66. The claw shaft 35 projects rearward from the rear surface of the mission case 7 via a chain case 34, a universal joint, or the like.
It is interlocked and connected to the TO axis 49 (see FIG. 2).

Then, as shown in FIG. 2, the power of the engine 5 is the main transmission mechanism 41 and the forward / backward switching mechanism 4.
2. The power of the engine 5 is transmitted to the rear wheels 4 and 4 via the auxiliary transmission mechanism 43, the rear wheel differential mechanism 44, etc., and the power of the engine 5 is transmitted to the main transmission mechanism 41, the forward / backward switching mechanism 42, and the auxiliary transmission mechanism. It is transmitted to the front wheels 3.3 in sequence via the front wheel drive switching mechanism 45, the front wheel differential mechanism 46, and the like. The continuously variable transmission 41a of the main transmission mechanism 41 is composed of a hydraulic continuously variable transmission, but is not limited to this, and may be composed of a belt type or toroidal type CVT or the like. As a result, the front wheels 3 and 3 and the rear wheels 4 and 4 are rotationally driven, and the tractor 1 travels. also,
The power of the engine 5 is sequentially transmitted to the claw shaft 35 of the rotary tiller 30 via the PTO clutch mechanism 47, the PTO transmission mechanism 48, the PTO shaft 49, and the like. As a result, the tilling claws 31 and 31 ... Are rotationally driven together with the claw shaft 35, and the tilling work is performed.

Next, a configuration related to control of the tractor 1 will be described.

The control device 100 is provided at an arbitrary position of the tractor 1. The control device 100 is composed of a central processing unit, a storage device, and the like. As shown in FIG. 3, the control device 100 includes a vehicle speed detecting means 61, a forward / backward switching lever 62, a gear ratio setting means 63, a gear ratio detecting means 64, and the like.
The tillage depth setting means 65, the tillage depth detecting means 66, the PTO switch 67, the PTO lever 68, the PTO switching dial 69, the engine rotation speed setting means 70, the engine rotation speed detecting means 71, and the elevating position setting means. 72, the elevating position detecting means 73, the output detecting means 74, the control selection switch 80, the mode operation switch 81, and the engine speed change amount setting dial 8.
2, the vehicle speed change amount setting dial 83, the threshold value setting dial 84, and the display unit 85 are connected. Further, the control device 100 includes a speed change actuator 91 and an elevating actuator 92.
Is connected.

The vehicle speed detecting means 61 detects the actual traveling speed (vehicle speed) of the tractor 1. In the present embodiment, the vehicle speed detecting means 61 is configured to detect the rotation speed of the axle in the rear wheel 4. The vehicle speed detecting means 61 is composed of a magnetic pickup coil, a rotary encoder, or the like, and the detection value detected by the vehicle speed detecting means 61 is transmitted to the control device 100 as the vehicle speed V.

The forward / backward switching lever 62 sets the traveling direction of the tractor 1. The forward / backward switching lever 62 includes a sensor for detecting an operation position, and the operation position detected by this sensor is transmitted to the control device 100. The control device 100 transmits a signal to the solenoid valve based on the operation position to drive the hydraulic actuator, and “on” or “off” the forward clutch 42a and the reverse clutch 42b (see FIG. 2) of the forward / backward switching mechanism 42. To operate. Specifically, when the forward / backward switching lever 62 is operated to the "forward" position, the forward clutch 4 of the forward / backward switching mechanism 42
When 2a is operated to "on" and operated to the "reverse" position, the reverse clutch 42b is "on".
When operated to the "neutral" position, the forward clutch 42a and the reverse clutch 42
Operate b "off".

The gear ratio setting means 63 sets the gear ratio of the continuously variable transmission 41a in the main gear shifting mechanism 41. The gear ratio setting means 63 is composed of, for example, a main shift lever and a speed adjustment dial. The gear ratio setting means 63 includes a sensor for detecting an operation amount, and the operation amount detected by this sensor is transmitted to the control device 100 as a target gear ratio, and the control device 100 transmits a target based on the target gear ratio. The vehicle speed Vs is determined.

The gear ratio detecting means 64 detects the gear ratio of the continuously variable transmission 41a in the main gear shifting mechanism 41. The gear ratio detecting means 64 is, for example, a sensor that detects the angle of the swash plate of the hydraulic pump or the hydraulic motor of the continuously variable transmission, and the signal detected by this sensor is the gear ratio (actually) of the actual continuously variable transmission 41a. It is transmitted to the control device 100 as a gear ratio). The auxiliary shift position detecting means 88 detects the shift position of the auxiliary shift lever. However, the shift position of the slider of the auxiliary transmission mechanism 43 may be detected and is not limited thereto. This detection signal is transmitted to the control device 100. In this embodiment, the high position and the low position are detected.

The tilling depth setting means 65 sets the tilling depth of the tilling claw 31 in the rotary tilling device 30 to an arbitrary tilling depth. The plowing depth setting means 65 is, for example, a plowing depth setting dial that can be rotated. The tillage depth setting means 65 includes a sensor for detecting the operation amount, and the operation amount detected by this sensor is transmitted to the control device 100 as the target tillage depth.

The tillage depth detecting means 66 detects the tillage depth of the rotary tillage device 30. The tillage depth detecting means 66 is, for example, a cover angle sensor (not shown) that detects the rotation angle of the rear cover 33 with respect to the tillage cover 32 (the opening degree of the rear cover 33), and the detection value of the cover angle sensor is the tillage depth. Now, it is transmitted to the control device 100.

The PTO switch 67 sets the transmission and cutoff of power to the PTO shaft 49. The PTO switch 67 includes a sensor for detecting an operating position, and the operating position detected by this sensor is transmitted to the control device 100. The control device 100 transmits a signal to the electromagnetic valve based on the operating positions of the PTO switch 67 and the PTO switching dial 69 described later to operate the hydraulic actuator, and is in opposition to the PTO clutch 47a of the PTO clutch mechanism 47 and the PTO clutch 47a. The PTO brake 47b, which operates in a positive manner, is operated "on" or "off".

The PTO lever 68 changes the rotation speed and the rotation direction of the PTO shaft 49. PTO
The lever 68 is connected to a shifter that selectively changes the meshing of the transmission gear in the PTO transmission mechanism 48. In the present embodiment, the PTO lever 68 can be operated in the "forward rotation", "neutral", and "reverse rotation" positions, and the shifter of the PTO transmission mechanism 48 slides based on this operation.
The rotation speed and rotation direction of the PTO axis 49 are changed. The PTO lever 68 includes a sensor for detecting an operating position, and the operating position detected by this sensor is transmitted to the control device 100.

The PTO switching dial 69 switches the operation mode of the PTO clutch mechanism 47. The PTO switching dial 69 includes a sensor for detecting the operation position, and this sensor is connected to the control device 100. The PTO switching dial 69 can be switched to the "interlocking", "independent", or "elevating interlocking" position.

The engine rotation speed setting means 70 sets the rotation speed of the engine 5. The engine speed setting means 70 is composed of, for example, an accelerator lever and an accelerator pedal. The engine rotation speed setting means 70 includes a sensor such as a potentiometer for detecting the operation amount, and the operation amount detected by this sensor is transmitted to the control device 100 as the target engine rotation speed Ns.

The engine rotation speed detecting means 71 detects the rotation speed of the engine 5. The engine rotation speed detecting means 71 is configured to detect, for example, the rotation speed of the flywheel or the crank shaft of the engine 5. The engine rotation speed detecting means 71 is composed of a magnetic pickup coil, a rotary encoder, or the like, and the signal detected by the engine rotation speed detecting means 71 is transmitted to the control device 100 as the engine rotation speed Nr.

The elevating position setting means 72 sets the height of the rotary tillage device 30 with respect to the vehicle body of the tractor 1. The elevating position setting means 72 is, for example, a working machine elevating lever for raising and lowering the working machine to an arbitrary height, a working machine raising switch and a working machine lowering switch for raising and lowering a predetermined position (raising position or lowering position) set in advance. It is said that. The work equipment elevating lever, the work equipment up switch, and the work equipment down switch are provided with a sensor for detecting the operation amount, and the operation amount detected by this sensor is the target up / down position (target rotation of the lift arms 24 and 24 described later). Angle αs
), Which is transmitted to the control device 100.

The elevating position detecting means 73 detects the height of the rotary tilling device 30 with respect to the vehicle body of the tractor 1, and is arranged at the base of the lift arm 24.

The output detecting means 74 detects the output of the engine 5. The output detecting means 74
For example, a signal related to the fuel injection pattern of the fuel injection device, which is calculated from the fuel injection amount of the fuel injection device, is transmitted to the control device 100. The control device 100 can calculate the output of the engine 5 based on the signal. The output detecting means 74 is not limited to the fuel injection device, and may be any device that can detect the output of the engine 5.

In the present embodiment, the load detecting means is composed of the control device 100 and the engine speed detecting means 71. The control device 100 calculates the load factor L of the engine 5 based on the engine rotation speed Nr detected by the engine rotation speed detecting means 71. In the present embodiment, the load detecting means detects the load by calculating the load factor L of the engine 5.
The load is not limited to this, and the load may be detected by calculating, for example, the engine down amount or the traction torque.

The control selection switch 80, the mode operation switch 81, the engine speed change amount setting dial 82, and the vehicle speed change amount setting dial 83 are provided on the operation panel 86 as shown in FIG. The operation panel 86 is provided on the side of the steering wheel column of the steering handle 11. Further, the threshold value setting dial 84 is provided in the operation operation unit 10. However, it may be provided on the operation panel 86.

The control selection switch 80 constitutes a selection means for selecting "on" or "off" for engine speed control and vehicle speed control. Each time the control selection switch 80 is pressed, the "on" or "off" of the engine speed control and the vehicle speed control is changed.

The mode operation switch 81 constitutes an operation means for setting on / off between the heavy load mode and the light load mode. Heavy load mode "OFF" each time the mode operation switch 81 is pressed
And light load mode "off", heavy load mode "on" and light load mode "off", heavy load mode "off"
It is sequentially changed to one of four states, "off" and light load mode "on", and heavy load mode "on" and light load mode "on". The on / off of the heavy load mode and the light load mode is displayed by the indicator lamps 86b and 86c, respectively.

The engine speed change amount setting dial 82 and the vehicle speed change amount setting dial 83 constitute a changing means capable of arbitrarily changing the engine speed change amount and the vehicle speed change amount in the heavy load mode and the light load mode. It is something to do.

The engine rotation speed change amount setting dial 82 is a means for setting an allowable amount for increasing or decreasing the engine rotation speed from the target engine rotation speed Ns. The allowable amount can be set, for example, from 0 rpm to 500 rpm. Engine speed change amount setting dial 82
When the allowable amount is set to 0 rpm by operating, the engine speed is not controlled regardless of the selection of "ON" or "OFF" by the control selection switch 80 and the mode selection by the mode operation switch 81. ..

The vehicle speed change amount setting dial 83 is a means for setting a vehicle speed change amount (deceleration rate). For example, the deceleration rate can be set between 0% and 50%. When the deceleration rate is set to 0% by operating the vehicle speed change amount setting dial 83, regardless of the selection of "ON" or "OFF" by the control selection switch 80 and the mode selection by the mode operation switch 81. No vehicle speed control is performed.

The threshold value setting dial 84 sets a threshold value for changing the set first heavy load value L1, second double load value L2, first light load value L3, and second light load value L4 in the heavy load mode and the light load mode. It constitutes a means. Here, the first heavy load value L1 is a lower limit load value for increasing the engine speed in the heavy load mode, and the second double load value L2 is a lower limit load value for reducing the vehicle speed. The first heavy load value L1 and the second double load value L2 may be equal values. Further, the first light load value L3 is the upper limit load value for returning the changed vehicle speed to the original in the light load mode, and the second light load value L4 is the engine speed in the light load mode. This is the upper limit load value to be reduced. The first light load value L3 and the second light load value L4 may be equal to each other. The threshold setting dial 84 may set a threshold for starting the increase in the engine speed and the vehicle speed in the heavy load mode, or a threshold for starting the decrease in the engine speed and the increase in the vehicle speed in the light load mode. can.

The display unit 85 is provided in the operation unit 10. As shown in FIG. 5, the display unit 85 has a display unit 85.
By operating the control selection switch 80, the indicator lamp 85a is turned on when the engine speed control and the vehicle speed control are "on", and turned off when the control selection switch 80 is "off". Further, by operating the control selection switch 80, the indicator lamp 86a is turned on when the control selection switch 80 is "on" and turned off when the control selection switch 80 is "off". Further, when the control selection switch 80 is “ON”, the indicator lamp 85a is also turned on at the same time. The position of the indicator lamp 85a is not limited. Further, by operating the mode operation switch 81, the indicator lamps 86b and 86c are turned on or off to indicate whether the mode is the heavy load mode or the light load mode.

Further, the display unit 85 displays that the engine speed is increasing or decreasing, or that the vehicle speed is decreasing. The display unit 85 is provided with a lamp that lights up when the engine speed is actually increasing or decreasing by a certain number. In the present embodiment, a lamp that lights up when the engine speed is increasing by 50 rpm or decreasing by 50 rpm is provided. Further, the display unit 85 has a liquid crystal unit 85b.
Is provided, and when the vehicle speed is decreasing by a constant speed, the liquid crystal display unit 85b displays that the vehicle speed is decreasing. In the present embodiment, a downward arrow is displayed on the liquid crystal unit 85b when the vehicle speed is reduced by 5% or more.

The engine speed change speed in the heavy load mode and the light load mode is determined by the auxiliary transmission mechanism 43.
It is switched according to the shift position of. The shift position of the auxiliary shift mechanism 43 is detected by the auxiliary shift position detecting means 88. For example, when the auxiliary transmission mechanism 43 is in a low speed state, the speed at which the engine speed is increased is increased. Further, when the auxiliary transmission mechanism 43 is in the high speed state,
Slow down the speed at which the engine speed is increased. Further, the higher the engine speed, the larger the amount of change. Specifically, the operating speed of the engine rotation speed changing actuator 93 is changed by a predetermined amount. In addition, the vehicle speed change speed is increased in the vehicle speed increase mode and slowed in the vehicle speed decrease mode.
Specifically, the operating speed of the speed change actuator 91 is changed by a predetermined amount.

The speed change actuator 91 changes the speed change ratio of the continuously variable transmission 41a in the main speed change mechanism 41, that is, the swash plate angle. The speed change actuator 91 is composed of an electromagnetic proportional valve, a cylinder, a motor and the like. The speed change actuator 91 is driven based on the signal transmitted from the control device 100 to change the swash plate angle of the stepless speed change device 41a, and the main speed change mechanism 41
The gear ratio of is changed. The control device 100 drives and controls the speed change actuator 91 so that the actual gear ratio detected by the gear ratio detecting means 64 matches the target gear ratio set by the gear ratio setting means 63, and is a stepless speed change device. The gear ratio of 41a is changed.

The elevating actuator 92 raises and lowers the rotary tillage device 30 with respect to the vehicle body. The lifting actuator 92 includes a hydraulic cylinder that rotates the lift arms 24 and 24, a solenoid valve that switches the amount and direction of pressure oil sent to the hydraulic cylinder, and the like.
The elevating actuator 92 is driven based on the signal transmitted from the control device 100 to change the height of the rotary tillage device 30.

The engine rotation speed changing actuator 93 changes the engine rotation speed. In the case of an electronic governor, the engine speed change actuator 93 is a rack actuator.
In the case of the common rail type, it is composed of injectors. Engine speed change actuator 9
3 is driven based on the signal transmitted from the control device 100 to change the fuel injection amount.
The engine speed is being changed. The control device 100 drives and controls the engine rotation speed changing actuator 93 so that the engine rotation speed Nr matches the target engine rotation speed Ns.

Hereinafter, the control mode of the tractor 1 will be described in detail.

The calculation of the output of the engine 5 and the load factor L by the control device 100 will be described. The control device 100 constantly calculates the output (PS) of the engine 5. Specifically, the control device 100
A map (not shown) showing the relationship between the fuel injection pattern of the fuel injection device (for example, the fuel injection amount, the number of fuel injections, the fuel injection timing, etc.) and the output of the engine 5 is stored in advance in the fuel injection device. The control device 100 calculates the output of the engine 5 based on the fuel injection pattern of the fuel injection device and the map.

The control device 100 constantly calculates the load factor L of the engine 5. Here, the load factor L according to the present embodiment means the ratio (%) of the actual injection amount to the maximum fuel injection amount when the engine 5 is driven at a certain rotation speed. Specifically, the control device 100 has an engine speed Nr.
A map showing the relationship between the output and the load factor L is stored in advance for each. The control device 100 calculates the load factor L of the engine 5 based on the engine rotation speed Nr detected by the engine rotation speed detecting means 71, the calculated output of the engine 5, and the map.

Hereinafter, the mode of controlling the engine speed and the vehicle speed by the control device 100 will be described with reference to FIGS. 6 to 9.

First, in FIG. 6, it is determined whether or not the control selection switch 80 is “on” (
Step S10). If the control selection switch 80 is “OFF”, the process returns to step S10 again. When the control selection switch 80 is “ON”, it is next determined whether or not the heavy load mode is selected (step S20). When the heavy load mode is selected, it is further determined whether or not the light load mode is selected (step S30). If the light load mode is selected, the process proceeds to step S100. If the light load mode is not selected, the process proceeds to step S200. If the heavy load mode is not selected in step S20, it is further determined whether or not the light load mode is selected (step S40). If the light load mode is selected, the process proceeds to step S300. If the light load mode is not selected, the process proceeds to step S400.

<Heavy load mode / engine speed increase step>
In step S100 shown in FIG. 7, it is determined whether or not the calculated load factor L is larger than the set heavy load value L1. When the load factor L is larger than the heavy load value L1, it is determined whether or not the engine speed Nr is smaller than the engine speed upper limit value Nmax ().
Step S105) If the load factor L is equal to or less than the heavy load value L1, the process proceeds to step S120. In step S105, the engine speed Nr is the engine speed change upper limit value Nm.
When it is smaller than ax, the engine rotation speed changing actuator 93 is driven to increase the engine rotation speed Nr (step S110). Then, the process returns to step S100. In step S105, when the engine speed Nr is equal to or higher than the engine speed upper limit value Nmax, the engine speed upper limit value Nmax is maintained and the process proceeds to step S120.

<Heavy load mode / vehicle speed reduction step>
In step S120, it is determined whether or not the load factor L is larger than the heavy load value L2. When the load factor L is larger than the heavy load value L2, the target vehicle speed Vs is the vehicle speed lower limit value Vm.
It is determined whether or not it is faster than in (step S125). Load factor L is heavy load value L2
In the following cases, the process proceeds to step S140. In step S125, when the vehicle speed V is faster than the vehicle speed lower limit value Vmin, the speed change actuator 91 is driven by driving the speed change actuator 91.
The vehicle speed V is reduced (step S130). Then, the process returns to step S120. In step S125, when the target vehicle speed Vs is equal to or less than the vehicle speed lower limit value Vmin, the target vehicle speed V
The process proceeds to step S140 while maintaining s at the vehicle speed lower limit value Vmin.

<Light load mode / vehicle speed return step>
In step S140 shown in FIG. 7, it is determined whether or not the load factor L is smaller than the light load value L3. When the load factor L is smaller than the light load value L3, the vehicle speed V and the target vehicle speed V
It is determined whether or not s is the same (step S145), and the load factor L is the light load value L3.
In the above cases, the engine speed and vehicle speed are maintained because the load is within the appropriate load range. In step S145, when the vehicle speed V is not the target vehicle speed Vs, the vehicle speed V is set to the target vehicle speed Vs by driving the speed change actuator 91 (step S150). Then, the process proceeds to step S140. In step S145, when the vehicle speed V is the target vehicle speed Vs, the process proceeds to step S160.

<Light load mode / engine speed reduction step>
In step S160, it is determined whether or not the load factor L is smaller than the light load value L4. When the load factor L is smaller than the light load value L4, it is determined whether or not the engine rotation speed Nr is larger than the engine rotation speed lower limit value Nmin (step S165). When the load factor L is the light load value L4 or more, the engine speed and the vehicle speed are maintained, and the engine returns to the beginning. In step S165, when the engine speed Nr is larger than the engine speed lower limit value Nmin, the engine speed Nr is set by the engine speed change amount setting dial 82 by driving the engine speed change actuator 93. Reduce by the amount of change (
Step S170). Then, it returns to S160. In step S165, when the engine speed Nr is equal to or less than the engine speed lower limit value Nmin, the engine speed lower limit value N
Keep at min and return to the beginning.

<Heavy load mode / engine speed increase step>
In step S200 shown in FIG. 8, it is determined whether or not the load factor L is larger than the heavy load value L1. When the load factor L is larger than the heavy load value L1, the engine speed Nr
Is smaller than the engine speed upper limit value Nmax (step S20).
5). If the load factor L is equal to or less than the heavy load value L1, the process proceeds to step S220. In step S205, when the engine speed Nr is smaller than the engine speed upper limit value Nmax, the engine speed Nr is increased by driving the engine speed changing actuator 93 (step S210). Then, the process returns to step S200. Step S
In 205, when the engine speed Nr is equal to or higher than the engine speed upper limit value Nmax,
The process proceeds to step S220.

<Heavy load mode / vehicle speed reduction step>
In step S220, it is determined whether or not the load factor L is larger than the heavy load value L2. When the load factor L is larger than the heavy load value L2, the target vehicle speed Vs is the vehicle speed lower limit value Vm.
It is determined whether or not it is faster than in (step S225). Load factor L is heavy load value L2
In the following cases, return to the beginning. In step S225, the target vehicle speed Vs is the vehicle speed lower limit value V.
If it is larger than min, the vehicle speed V is reduced by driving the speed change actuator 91 (step S230). Then, the process returns to step S220. Step S225
When the target vehicle speed Vs is equal to or less than the vehicle speed lower limit value Vmin, the vehicle returns to the beginning.

<Light load mode / engine speed reduction step>
In step S300 shown in FIG. 9, it is determined whether or not the load factor L is smaller than the light load value L4. When the load factor L is smaller than the light load value L4, the engine speed Nr
Is larger than the lower limit of the engine speed Nmin (step S30).
5). When the load factor L is the heavy load value L4 or more, the process returns to the beginning. In step S305, when the engine speed Nr is larger than the engine speed lower limit value Nmin, the engine speed Nr is set by the engine speed change amount setting dial 82 by driving the engine speed change actuator 93. The change amount is reduced by the amount of change (step S310), and the process returns to step S300. In step S305, when the engine rotation speed Nr is equal to or less than the engine rotation speed lower limit value Nmin, the process returns to the beginning.

<No mode selection / Vehicle speed reduction step>
In step S400 shown in FIG. 10, it is determined whether or not the load factor L is larger than the heavy load value L2. When the load factor L is larger than the heavy load value L2, it is determined whether or not the target vehicle speed Vs is faster than the vehicle speed lower limit value Vmin (step S405). When the load factor L is equal to or less than the heavy load value L2, the process returns to the beginning. In step S405, when the target vehicle speed Vs is larger than the vehicle speed lower limit value Vmin, the vehicle speed V is reduced by driving the speed change actuator 91 (step S410). Then, the process returns to step S400. In step S405, when the target vehicle speed Vs is equal to or less than the vehicle speed lower limit value Vmin, the process returns to the beginning.

Hereinafter, an example of time changes in the load factor L, the engine speed Nr, and the vehicle speed V when the engine speed and the vehicle speed are controlled will be described with reference to FIG. 11. In this example,
The control selection switch 80 is in the “ON” state, and the heavy load mode and the light load mode are selected. Hereinafter, a case where the heavy load value L1 and the heavy load value L2 are equal and the light load value L3 and the light load value L4 are equal will be described.

When the load factor L becomes large and becomes larger than the heavy load value L1 (T1) and the state of being larger than the heavy load value L1 continues for a minute time d1, the engine speed changing actuator 93 is used. By driving, the engine speed Nr is increased. The length of the minute time d1 can be changed and can be set to 0. Engine speed N
The speed at which r is increased is determined based on the state of the auxiliary transmission mechanism 43. Next, from the time (T2) when the engine speed Nr becomes equal to or higher than the engine speed upper limit value Nmax, the minute time d2
Even when the engine speed Nr remains equal to or higher than the engine speed upper limit value Nmax during the period, the load factor L is larger than the heavy load value L2 (L1), so that the vehicle speed V is reduced.

The length of the minute time d2 can be changed and can be set to 0. The speed at which the vehicle speed V is reduced is determined based on the state of the auxiliary transmission mechanism 43. The decrease in vehicle speed V continued until the time when the load factor L became the heavy load value L2 (L1) or less (T3), and after T3, the engine speed Nr remained at the upper limit of change and the vehicle speed V decreased at T3. Maintained at speed. Further, if the load factor L remains smaller than the light load value L3 for a minute time d3 from the time when the load factor L becomes smaller than the light load value L3 (T4), the vehicle speed V becomes higher. Since it is different from the target vehicle speed Vs, the vehicle speed V is increased in order to return to the target vehicle speed Vs. The length of the minute time d3 can be changed and can be set to 0. Even when the vehicle speed V becomes equal to the target vehicle speed Vs (T5), the load factor L is the light load value L4 (L3).
When a smaller state is maintained for a minute time d4, the engine speed Nr is reduced by driving the engine speed changing actuator 93. The length of the minute time d4 can be changed and can be set to 0. Engine speed Nr
The speed at which is increased is determined based on the state of the auxiliary transmission mechanism 43. The decrease in engine speed Nr continues until the time when the load factor L becomes the light load value L4 (L3) or more (T6), and after T6, the engine speed Nr remains the reduced engine speed at T6 and the vehicle speed. V is maintained at the target vehicle speed Vs.

Further, when the engine speed change amount setting dial 82 is operated during engine speed and vehicle speed control and the engine speed upper limit value Nmax or the engine speed lower limit value Nmin is changed, the changed engine speed upper limit is changed. The engine speed Nr is changed so as to be equal to or less than the value Nmax or to be equal to or more than the changed lower limit value of the engine speed Nmin.

For example, as shown in FIG. 12, when the engine speed Nr is increased from T7 and the engine speed is maintained at N1 from the time when the engine speed is increased to N1 (T8), the engine is maintained at T9. When the engine speed upper limit value Nmax decreases from Nmax1 to Nmax2 by operating the rotation speed change amount setting dial 82, the engine speed change actuator 93 is driven from T9 to reduce the engine speed Nr to Nmax.
Gradually decrease until it reaches 2. Then, at T10, the engine speed Nr is Nmax.
When it reaches 2, the engine speed and the vehicle speed are controlled again.

Further, when the engine rotation speed setting means 70 is operated during the engine rotation speed and vehicle speed control to change the target engine rotation speed Ns, the increase / decrease of the target engine rotation speed Ns is added to the engine rotation speed Nr at that time. Is increased or decreased. For example, as shown in FIG. 13, the engine speed Nr is maintained at N2 from the time point (T12) when the engine speed Nr is increased from T11 and the engine speed Nr is raised from the target engine speed Ns1 to N2. If you are,
By operating the engine speed setting means 70 in T13, the target engine speed N
When s increases from Ns1 to Ns2, the engine rotation speed Nr is gradually increased from T13 by the difference d between Ns2 and Ns1 by driving the engine rotation speed changing actuator 93. Then, when the engine speed Nr becomes N2 + d at T14, the engine speed Nr is maintained as it is.

Further, when the engine rotation speed setting means 70 is being operated, the engine rotation speed and vehicle speed control are temporarily suspended. That is, when the target engine speed Ns fluctuates, the load factor L fluctuates greatly, so that the engine speed and vehicle speed control are temporarily suspended.

Further, by operating the control selection switch 80 during engine speed and vehicle speed control,
When the control selection switch is changed from "ON" to "OFF", the engine speed Nr and the vehicle speed V are set to the target engine speed Ns and the target by driving the engine speed change actuator 93 and the speed change actuator 91. Gradually return to vehicle speed Vs.

As described above, the tractor 1 includes the engine rotation speed detecting means 71, the engine rotation speed setting means 70, the engine rotation speed changing actuator 93, the vehicle speed detecting means 61, the stepless speed change device 41a, and the stepless speed change device. In a tractor including a speed change actuator 91 for shifting 41a, a control device 100 as load detection means, an engine rotation speed detection means 71, and an output detection means 74, and a control device 100 for controlling engine rotation speed and vehicle speed. When the engine load factor L becomes larger than the set heavy load value L1, the engine rotation speed Nr is increased while maintaining the vehicle speed V constant, and the engine rotation speed Nr is increased to the engine rotation speed upper limit value Nmax. When the engine load factor L becomes larger than the set heavy load value L2, the heavy load mode for controlling the engine rotation speed changing actuator 93 and the speed change actuator 91 and the engine load factor so as to reduce the vehicle speed V, and the engine load factor. When L becomes smaller than the set light load value L4, a light load mode that controls the engine rotation speed changing actuator 93 and the speed change actuator 91 so as to reduce the engine rotation speed Nr while maintaining the vehicle speed V constant. And. With this configuration, when the heavy load mode is selected during heavy load, the engine speed Nr can be increased, the vehicle speed V can be reduced, engine stall can be prevented, and work efficiency can be improved. .. Further, in the case of a light load, when the light load mode is selected, the engine rotation speed Nr can be reduced by the engine rotation speed changing actuator 93, and the vehicle can run with low fuel consumption.

Further, it is provided with an engine rotation speed change amount setting dial 82 and a vehicle speed change amount setting dial 83 that can arbitrarily change the change amount of the engine rotation speed Nr and the change amount of the vehicle speed V in the heavy load mode and the light load mode. Is. With this configuration, the amount of change in engine speed Nr and the amount of change in vehicle speed V in each mode can be changed according to the user's preference, work mode, and field conditions, and work efficiency can be improved. Can be improved.

Further, the mode operation switch 81 for setting the on / off of the control of the engine rotation speed changing actuator 93 by setting the on / off for the heavy load mode or the light load mode is provided. With this configuration, the heavy load mode or the light load mode can be arbitrarily selected by turning on / off the mode operation switch 81 according to the user's preference.

Further, the set heavy load value L1 and heavy load value L2 in the heavy load mode and the light load mode.
The light load value L3 and the light load value L4 set as described above can be changed by the threshold value setting dial 84. With this configuration, the threshold value in each mode can be changed according to the user's preference, work mode, and field condition, the work finish can be improved, and engine stall can be prevented.

Further, the auxiliary transmission mechanism 43 is provided as a setting means for setting the engine speed change speed and the vehicle speed change speed in the heavy load mode and the light load mode. With this configuration, the threshold value in each mode can be changed according to the user's preference, work mode, and field condition, the work finish can be improved, and engine stall can be prevented.

Further, the display unit 85 for displaying the heavy load mode and the light load mode is provided. With this configuration, the work vehicle setting state can be easily confirmed.

1 tractor 5 engine 61 vehicle speed detection means 70 engine speed setting means 71 engine speed detection means 80 control selection switch 81 mode operation switch 82 engine speed change amount setting dial 83 vehicle speed change amount setting dial 84 threshold setting dial 85 display unit 91 Speed change actuator 93 Engine speed change actuator 100 Control device

Claims (1)

A control device that controls the engine speed and vehicle speed,
And a engine rotational speed change amount setting means capable of setting a permissible capacity of the engine speed to reduce the engine revolution speed set by the accelerator lever,
The control device is
When the load of the engine is lightly loaded than the predetermined load value, while keeping the vehicle speed constant, while performing control to reduce the engine rotational speed within a pre-Symbol tolerance,
The control is stopped based on the operation of the accelerator pedal.
A work vehicle characterized by that.

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