JP6516307B2 - Work vehicle - Google Patents

Description

  The present invention relates to work vehicle technology.

  2. Description of the Related Art Conventionally, among working vehicles such as tractors, one that transmits rotational power of an engine to a traveling device via a stepless transmission is known. The work vehicle includes an accelerator lever and an accelerator pedal, which are engine rotation number setting means for setting an engine rotation number at a normal time. In addition, work vehicles that change the vehicle speed according to the engine load represented by an engine load factor, an engine down amount, a traction torque or the like at the time of work are also known. When the engine load is large (heavy load), the vehicle speed is reduced to prevent engine stalling. Further, when the engine load is small (at the time of light load), the vehicle speed is increased to improve the travelability.

Unexamined-Japanese-Patent No. 2007-315472

  However, when the vehicle speed is increased at light load, the drivability is improved, but the engine speed also increases more than necessary, so that the fuel efficiency can not be improved.

  Therefore, in view of the problems, the present invention aims to provide a work vehicle that can travel with low fuel consumption at light load and can improve work efficiency.

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

According to the present invention, the control device for controlling the engine speed and the vehicle speed, and the engine speed change amount setting means capable of setting the allowable amount of the engine speed to be decreased from the engine speed set by the accelerator lever. The control device executes control to reduce the engine speed within the allowable range while maintaining the vehicle speed constant when the load on the engine is smaller than a predetermined load value, By operating the selection means to select "on" or "off" of the engine speed control and the vehicle speed control while executing the control, the engine speed control and the vehicle speed control are switched from "on" to "off" When it is changed to V, the working vehicle returns the engine speed to the engine speed set by the accelerator lever.

In the second aspect, the control device maintains the vehicle speed at a constant speed when the mode permitting reduction of the engine speed is executed and the load of the engine is lighter than the predetermined load value. While, the control is performed to reduce the engine speed within the allowable range .

  The effects of the present invention are as follows.

  According to the present invention, at the time of light load, the work vehicle can be made to travel with low fuel consumption by reducing the engine rotational speed while maintaining the vehicle speed constant. In addition, the work efficiency of the work vehicle can be improved.

The whole side view of the tractor concerning one embodiment of the present invention. The figure which shows the power transmission structure of a tractor. The block diagram which shows the composition concerning control of a tractor. FIG. 2 is a plan view showing an operation panel. The top view which shows a display part. The 1st flow chart figure showing the control mode of engine number of rotations and vehicle speed control. The 2nd flow chart figure showing the control mode of engine number of rotations and vehicle speed control. The 3rd flow chart figure showing the control mode of engine number of rotations and vehicle speed control. The 4th flow chart figure showing the control mode of engine number of rotations and vehicle speed control. The 5th flow chart figure showing the control mode of engine number of rotations and vehicle speed control. The graph which shows the relationship between load, an engine speed, and a vehicle speed, and time. The graph which shows the relationship between the engine speed and time at the time of engine speed upper limit change. The graph which shows the relationship between the engine speed at the time of target engine speed change, and time.

  Next, the whole structure of the tractor 1 which concerns on one Embodiment of this invention is demonstrated.

  As shown in FIG. 1, in the tractor 1, the vehicle body frame 2 is disposed with the longitudinal direction as the front and rear direction, and is supported by the left and right front wheels 3 and 3 at the front via the front axle, It is supported by a pair of left and right rear wheels 4 and 4 via a rear axle. An engine 5 is provided at the front of the fuselage frame 2 and is covered by a bonnet 6. A transmission case 7 is provided at the rear of the fuselage frame 2 for storing a part of the power transmission mechanism of the tractor 1.

  A cabin 8 is disposed behind the bonnet 6, and a driving operation unit 10 is provided inside the cabin 8 for a worker to ride and operate the tractor 1. In the driving operation unit 10, a steering handle 11 is provided at the front, and a seat 12 is disposed at the rear of the steering handle 11. A gear ratio setting unit 63, a position lever (or position switch) serving as an elevation position setting unit 72, and a depth setting unit 65 are disposed on the side of the seat 12, and the steering column side portion of the steering handle 11 is disposed. An accelerator lever serving as an engine rotational speed setting means 70 and a forward / backward switching lever 62 are disposed at the same position (see FIG. 3). An accelerator pedal (engine speed setting means 70), a brake pedal, a main clutch pedal, a differential lock pedal, etc. are disposed on the lower front step of the seat 12.

  The work implement coupling device 20 mainly includes a top link 21, lower links 22 and 22, and lift rods 23 and 23. The top link 21 is rotatably connected to a top link bracket fixed to the rear of the transmission case 7. The lower links 22 are rotatably connected to both sides of the transmission case 7 or the rear axle housing. One end of the lift rod 23 is rotatably connected to the middle portion of the lower link 22 and the other end is rotatably connected to a lift arm 24 projecting backward from the hydraulic case. . At the rotation base of the lift arm 24, a position sensor serving as the elevation position detection means 73 is disposed. In the present embodiment, a rotary tilling device 30 is connected to the rear ends of the top link 21 and the lower links 22 and 22 as a working machine. However, the working machine is not limited to the rotary cultivating device 30, and a drug spreader, a mower, a rake or the like can be mounted.

  The rotary tilling device 30 includes a tilling claw 31, a tilling cover 32, a rear cover 33, a chain case 34 and the like. The tilling claws 31, 31... Are radially installed at appropriate intervals on the claw shaft 35 which is horizontally mounted so as to be rotatable in the left-right direction, and the rotation locus 36 of the tip of the tilling claws 31, 31. A tilling cover 32 is disposed to cover the upper side and the side. The front end of the rear cover 33 is pivotally connected to the rear end of the tillage cover 32, and the rotation of the rear cover 33 is detected by a cover angle sensor serving as the depth measuring means 66. The claw shaft 35 is interlockingly connected to a PTO shaft 49 projecting rearward from the rear surface of the transmission case 7 via a chain case 34, a universal joint or the like (see FIG. 2).

  Then, as shown in FIG. 2, the power of the engine 5 is transmitted to the rear wheels 4 and 4 sequentially through the main transmission mechanism 41, the forward / reverse switching mechanism 42, the auxiliary transmission mechanism 43, the rear wheel differential mechanism 44, etc. The power of the engine 5 is transmitted to the front wheels 3 and 3 sequentially through the main transmission mechanism 41, the forward / reverse switching mechanism 42, the sub transmission mechanism 43, the front wheel drive switching mechanism 45, the front wheel differential mechanism 46, and so on. Ru. Although the continuously variable transmission 41a of the main transmission mechanism 41 is constituted by a hydraulic stepless transmission, it is not limited and may be constituted by 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. Further, the motive power of the engine 5 is transmitted to the claw shaft 35 of the rotary cultivating device 30 through the PTO clutch mechanism 47, the PTO transmission mechanism 48, the PTO shaft 49 and the like sequentially. Thus, the tilling claws 31 are driven to rotate together with the claw shaft 35, and the tilling operation is performed.

  Next, the configuration regarding 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 configured of a central processing unit, a storage device, and the like. In the control device 100, as shown in FIG. 3, the vehicle speed detecting means 61, the forward / reverse switching lever 62, the gear ratio setting means 63, the gear ratio detecting means 64, the tillage setting means 65, and the tillage detection Means 66, PTO switch 67, PTO lever 68, PTO switching dial 69, engine speed setting means 70, engine speed detection means 71, elevation position setting means 72, elevation position detection means 73, Output detection means 74, control selection switch 80, mode operation switch 81, engine speed change amount setting dial 82, vehicle speed change amount setting dial 83, threshold value setting dial 84, and display unit 85 are connected. . Further, a speed change actuator 91 and an elevation actuator 92 are connected to the control device 100.

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

  The forward / reverse switching lever 62 sets the traveling direction of the tractor 1. The forward / reverse switching lever 62 includes a sensor that detects 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 turns on or off the forward clutch 42a and the reverse clutch 42b (see FIG. 2) of the forward / reverse switching mechanism 42. To activate. Specifically, when the forward / reverse switching lever 62 is operated to the “forward” position, the forward clutch 42 a of the forward / backward switching mechanism 42 is operated to “on”, and when operated to the “reverse” position, the reverse clutch 42 b Is turned "on" and operated to the "neutral" position, the forward clutch 42a and the reverse clutch 42b are turned "off".

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

  The transmission ratio detection means 64 detects the transmission ratio of the continuously variable transmission 41 a in the main transmission mechanism 41. The gear ratio detection means 64 is, for example, a sensor for detecting a hydraulic pump of a continuously variable transmission or a swash plate angle of a hydraulic motor, and a signal detected by this sensor is an actual gear ratio of the continuously variable transmission 41a It is transmitted to the control device 100 as a transmission gear ratio. The sub shift position detection means 88 detects the shift position of the sub shift lever. However, the shift position of the slider of the auxiliary transmission mechanism 43 may be detected without limitation. The detection signal is transmitted to the control device 100. In the present embodiment, the high position and the low position are detected.

  The plow depth setting means 65 sets the plow depth of the tiller 31 in the rotary tiller 30 to an arbitrary plow depth. The plow depth setting means 65 is, for example, a plow depth setting dial capable of turning operation. The plow 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 plow depth.

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

  The PTO switch 67 sets power transmission and shutoff to the PTO shaft 49. The PTO switch 67 includes a sensor that detects 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 PTO switch 67 and the operation position of the PTO switching dial 69 described later to operate the hydraulic actuator, and the PTO clutch 47a of the PTO clutch mechanism 47 and this PTO clutch 47a The PTO brake 47b, which operates in the same manner, is operated "on" or "off".

  The PTO lever 68 is for changing the number of rotations and the direction of rotation of the PTO shaft 49. The PTO lever 68 is connected to a shifter that selectively changes the meshing of the transmission gears in the PTO transmission mechanism 48. In the present embodiment, the PTO lever 68 is operable to the “forward rotation”, “neutral”, and “reverse rotation” positions, and the shifter of the PTO transmission mechanism 48 slides based on this operation, and the PTO shaft 49 is moved. The number of rotations and the direction of rotation are changed. The PTO lever 68 includes a sensor that detects an operation position, and the operation position detected by this sensor is transmitted to the control device 100.

  The PTO switching dial 69 is for switching the operating 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 “linked”, “independent”, or “vertically linked” position.

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

  The engine speed detecting means 71 detects the speed of the engine 5. The engine rotational speed detecting means 71 is configured to detect, for example, the rotational speed of the flywheel of the engine 5 or a crankshaft. The engine rotational speed detection unit 71 includes a magnetic pickup coil, a rotary encoder, and the like, and a signal detected by the engine rotational speed detection unit 71 is transmitted to the control device 100 as an engine rotational speed Nr.

  The elevation position setting means 72 sets the height of the rotary cultivating device 30 with respect to the vehicle body of the tractor 1. The elevation position setting means 72, for example, a work implement lift lever for raising and lowering the work implement to an arbitrary height, a work implement lift switch and a work implement descend switch for raising and lowering to a predetermined position (raising position and lowering position) set in advance. It is assumed. These work implement raising and lowering levers, work implement raising switches and work implement lowering switches have sensors for detecting the operation amount, and the operation amount detected by this sensor is the target elevation position (the target pivoting of the lift arms 24 and 24 described later) It is transmitted to the control device 100 as the angle αs).

  The elevation position detection means 73 detects the height of the rotary cultivating device 30 relative to the vehicle body of the tractor 1 and is disposed at the base of the lift arm 24.

  The output detection means 74 detects the output of the engine 5. The output detection means 74 is calculated from, for example, the fuel injection amount of the fuel injection device, and a signal regarding the fuel injection pattern of this 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. Note that the output detection means 74 is not limited to the fuel injection device, as long as it can detect the output of the engine 5.

  The load detection means is constituted by the control device 100 and the engine rotational speed detection means 71 in the present embodiment. The control device 100 calculates the load factor L of the engine 5 based on the engine rotational speed Nr detected by the engine rotational speed detection means 71. Although the load detection means detects the load by calculating the load factor L of the engine 5 in the present embodiment, the present invention is not limited to this. For example, the engine down amount or the traction torque may be calculated. The load may be detected.

  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 column of the steering handle 11. Further, the threshold setting dial 84 is provided in the driving operation unit 10. However, it may be provided on the operation panel 86.

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

  The mode operation switch 81 constitutes operation means for setting on / off of the heavy load mode and the light load mode. Each time the mode operation switch 81 is pressed, the heavy load mode “off” and the light load mode “off”, the heavy load mode “on” and the light load mode “off”, the heavy load mode “off” and the light load mode “on” And the heavy load mode “on” and the light load mode “on” are sequentially changed to one of four states. The on / off of the heavy load mode and the light load mode is indicated 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 changing means capable of arbitrarily changing the change amount of the engine speed and the change amount of the vehicle speed in the heavy load mode and the light load mode. It is

  The engine speed change amount setting dial 82 is a means for setting an allowable amount of increase or decrease of the engine speed from the target engine speed Ns. The allowable amount can be set, for example, between 0 rpm and 500 rpm. When the engine rotational speed change amount setting dial 82 is operated to set the allowable amount to 0 rpm, regardless of the selection of “on” or “off” by the control selection switch 80 and the selection of the mode by the mode operation switch 81 , Does not perform engine speed control.

  The vehicle speed change amount setting dial 83 is a means for setting a change amount (deceleration rate) of the vehicle speed. For example, the deceleration rate can be set between 0% and 50%. When the vehicle speed change amount setting dial 83 is operated to set the deceleration rate to 0%, regardless of the selection of “on” or “off” by the control selection switch 80 and the selection of the mode by the mode operation switch 81, Vehicle speed control is not performed.

  The threshold setting dial 84 changes 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 the 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 dual 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 to each other. The first light load value L3 is the upper limit load value for restoring the changed vehicle speed in the light load mode, and the second light load value L4 is the engine speed in the light load mode. It is the upper limit load value that decreases. 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 that starts an increase in engine speed and a decrease in vehicle speed in the heavy load mode, or a threshold that starts a decrease in engine speed and an increase in the vehicle speed in the light load mode. it can.

  The display unit 85 is provided in the driving operation unit 10. As shown in FIG. 5, the display unit 85 turns on the display lamp 85a when the engine speed control and the vehicle speed control are "on" by the operation of the control selection switch 80, and turns off when the "off". Further, by the operation of the control selection switch 80, the display lamp 86a is turned on when the control selection switch 80 is "on", and is turned off when the control selection switch 80 is "off". Further, when the control selection switch 80 is "on", the display lamp 85a is also lighted simultaneously. The position of the display lamp 85a is not limited. Further, by operating the mode operation switch 81, the display 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 rotational 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 actually increases or decreases by a certain number. In the present embodiment, a lamp is provided which lights up when the engine speed is increased by 50 rpm or decreased by 50 rpm. In addition, the display unit 85 is provided with a liquid crystal unit 85b, and when the vehicle speed is decreasing by a constant speed, the liquid crystal unit 85b displays that the vehicle speed is decreasing. In the present embodiment, when the vehicle speed decreases by 5% or more, a downward arrow is displayed on the liquid crystal portion 85b.

  The engine speed changing speed in the heavy load mode and the light load mode is switched by the shift position of the auxiliary transmission mechanism 43. The shift position of the auxiliary transmission mechanism 43 is detected by the auxiliary shift position detection means 88. For example, when the auxiliary transmission mechanism 43 is in the low speed state, the speed of increasing the engine speed is increased. In addition, when the auxiliary transmission mechanism 43 is in the high speed state, the speed at which the engine speed is increased is reduced. Furthermore, the amount of change is increased as the engine speed is higher. Specifically, the operating speed of the engine speed changing actuator 93 is changed by a predetermined amount. Also, the vehicle speed change speed is made faster in the vehicle speed increase mode and made slower 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 transmission ratio of the continuously variable transmission 41 a in the main transmission mechanism 41, that is, the swash plate angle. The shift actuator 91 is configured of a solenoid proportional valve, a cylinder, a motor, and the like. The gear shift actuator 91 is driven based on a signal transmitted from the control device 100 to change the swash plate angle of the continuously variable transmission 41 a and to change the transmission gear ratio of the main transmission mechanism 41. The control device 100 drives and controls the shift actuator 91 so that the actual gear ratio detected by the gear ratio detection means 64 matches the target gear ratio set by the gear ratio setting means 63, and the continuously variable transmission The gear ratio of 41a has been changed.

  The raising and lowering actuator 92 is for raising and lowering the rotary cultivating device 30 with respect to the vehicle body. The lifting and lowering actuator 92 is composed of a hydraulic cylinder that rotates the lift arms 24 and a solenoid valve that switches the amount and direction of oil pressure supplied to the hydraulic cylinder. The elevation actuator 92 is driven based on the signal transmitted from the control device 100 to change the height of the rotary cultivating device 30.

  The engine speed change actuator 93 changes the engine speed. The engine speed changing actuator 93 is a rack actuator in the case of an electronic governor, and an injector in the case of a common rail type. The engine speed change actuator 93 is driven based on the signal transmitted from the control device 100 to change the fuel injection amount and change the engine speed. The control device 100 drives and controls the engine speed change actuator 93 so that the engine speed Nr matches the target engine speed Ns.

  Below, the control aspect of the tractor 1 is demonstrated 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 does not show 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. The map is pre-stored. 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 rotational speed. Specifically, in the control device 100, a map indicating the relationship between the output and the load factor L is stored in advance for each engine speed Nr. The control device 100 calculates the load factor L of the engine 5 based on the engine rotational speed Nr detected by the engine rotational speed detecting means 71, the calculated output of the engine 5, and the map.

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

  First, in FIG. 6, it is determined whether the control selection switch 80 is turned on (step S10). If the control selection switch 80 is "off", the process returns to step S10 again. If the control selection switch 80 is "ON", then it is determined whether the heavy load mode is selected (step S20). If the heavy load mode is selected, it is further determined whether 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 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 the calculated load factor L is larger than the set heavy load value L1. If the load factor L is larger than the heavy load value L1, it is determined whether the engine speed Nr is smaller than the engine speed upper limit Nmax (step S105), and the load factor L is less than the heavy load value L1. In the case, the process proceeds to step S120. In step S105, when the engine speed Nr is smaller than the engine speed change upper limit value Nmax, the engine speed change actuator 93 is driven to increase the engine speed Nr (step S110). Then, the process returns to step S100. In step S105, when the engine speed Nr is equal to or more 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 the load factor L is larger than the heavy load value L2. If the load factor L is larger than the heavy load value L2, it is determined whether the target vehicle speed Vs is faster than the vehicle speed lower limit value Vmin (step S125). When the load factor L is equal to or less than the heavy load value L2, the process proceeds to step S140. In step S125, when the vehicle speed V is higher than the vehicle speed lower limit value Vmin, the speed change actuator 91 is driven to decrease the vehicle speed V (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 Vs is maintained at the vehicle speed lower limit value Vmin, and the process proceeds to step S140.

<Light load mode / vehicle speed return step>
In step S140 shown in FIG. 7, it is determined whether 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, it is judged whether the vehicle speed V and the target vehicle speed Vs are the same (step S145), and the load factor L is the light load value L3 or more. Since the engine is in the proper load range, the engine speed and the vehicle speed are maintained. In step S145, when the vehicle speed V is not the target vehicle speed Vs, the transmission actuator 91 is driven to set the vehicle speed V to the target vehicle speed Vs (step S150). Then, the process proceeds to step S140. When it is determined in step S145 that 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 the load factor L is smaller than the light load value L4. If the load factor L is smaller than the light load value L4, it is determined whether the engine speed Nr is larger than the engine speed lower limit Nmin (step S165). When the load factor L is equal to or more than the light load value L4, the engine speed and the vehicle speed are maintained, and the process returns to the beginning. In step S165, when the engine rotational speed Nr is larger than the engine rotational speed lower limit value Nmin, the engine rotational speed change actuator 93 is driven to set the engine rotational speed Nr with the engine rotational speed change amount setting dial 82 The change amount is decreased (step S170). And it returns to S160. In step S165, when the engine speed Nr is equal to or less than the engine speed lower limit Nmin, the engine speed lower limit Nmin is maintained, and the process returns to the beginning.

<Heavy load mode / engine speed increase step>
In step S200 shown in FIG. 8, it is determined whether the load factor L is larger than the heavy load value L1. If the load factor L is larger than the heavy load value L1, it is determined whether the engine speed Nr is smaller than the engine speed upper limit Nmax (step S205). When 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 Nmax, the engine speed changing actuator 93 is driven to increase the engine speed Nr (step S210). Then, the process returns to step S200. In step S205, when the engine speed Nr is equal to or more than the engine speed upper limit Nmax, the process proceeds to step S220.

<Heavy load mode / vehicle speed reduction step>
In step S220, it is determined whether the load factor L is larger than the heavy load value L2. If the load factor L is larger than the heavy load value L2, it is determined whether the target vehicle speed Vs is faster than the vehicle speed lower limit value Vmin (step S225). When the load factor L is equal to or less than the heavy load value L2, the process returns to the beginning. In step S225, when the target vehicle speed Vs is larger than the vehicle speed lower limit value Vmin, the speed change actuator 91 is driven to decrease the vehicle speed V (step S230). Then, the process returns to step S220. In step S225, if the target vehicle speed Vs is equal to or less than the vehicle speed lower limit value Vmin, the process returns to the beginning.

<Light load mode / engine speed reduction step>
In step S300 shown in FIG. 9, it is determined whether the load factor L is smaller than the light load value L4. If the load factor L is smaller than the light load value L4, it is determined whether the engine rotational speed Nr is larger than the engine rotational speed lower limit Nmin (step S305). When the load factor L is equal to or more than the heavy load value L4, the process returns to the beginning. In step S305, when the engine rotational speed Nr is larger than the engine rotational speed lower limit value Nmin, the engine rotational speed change actuator 93 is driven to set the engine rotational speed Nr with the engine rotational speed change amount setting dial 82 The change amount is decreased (step S310), and the process returns to step S300. In step S305, if the engine speed Nr is less than or equal to the engine speed lower limit value Nmin, the process returns to the beginning.

<No mode selected / Vehicle speed reduction step>
In step S400 shown in FIG. 10, it is determined whether the load factor L is larger than the heavy load value L2. If the load factor L is larger than the heavy load value L2, it is determined whether 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 speed change actuator 91 is driven to decrease the vehicle speed V (step S410). Then, the process returns to step S400. In step S405, if the target vehicle speed Vs is equal to or less than the vehicle speed lower limit value Vmin, the process returns to the beginning.

  In the following, an example of temporal changes in load factor L, engine speed Nr, and vehicle speed V when engine speed and vehicle speed control are performed will be described using FIG. 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, the case where the heavy load value L1 is equal to the heavy load value L2 and the light load value L3 is equal to the light load value L4 will be described.

  When the load factor L increases and becomes larger than the heavy load value L1 (T1) and the state larger than the heavy load value L1 continues for a minute time d1, the engine speed change actuator 93 is By driving, the engine speed Nr is increased. The length of the minute time d1 can be changed, and can be set to zero. The speed at which the engine speed Nr is increased is determined based on the state of the auxiliary transmission mechanism 43. Next, even when the state where the engine speed Nr is equal to or more than the engine speed upper limit Nmax continues for a minute time d2 from the time (T2) when the engine speed Nr becomes the engine speed upper limit Nmax or more, Since the load factor L is larger than the heavy load value L2 (L1), the vehicle speed V is decreased.

  The length of the minute time d2 can be changed, and can be set to zero. The speed at which the vehicle speed V is decreased is determined based on the state of the auxiliary transmission mechanism 43. The decrease of the vehicle speed V continues until the point (T3) when the load factor L becomes equal to or less than the heavy load value L2 (L1), and after T3 the engine speed Nr remains at the change upper limit and the vehicle speed V decreases at T3. It is maintained at speed. Furthermore, from the point in time when the load factor L becomes smaller than the light load value L3 (T4), if the load factor L continues to be smaller than the light load value L3 during the minute time d3, the vehicle speed V becomes Since the vehicle speed V is different from the target vehicle speed Vs, the vehicle speed V is increased to return to the target vehicle speed Vs. The length of the minute time d3 can be changed, and can be set to zero. Even when the vehicle speed V becomes equal to the target vehicle speed Vs (T5), the engine speed is changed if the state in which the load factor L is smaller than the light load value L4 (L3) continues for the minute time d4. By driving the actuator 93, the engine speed Nr is reduced. The length of the minute time d4 can be changed, and can be set to zero. The speed at which the engine speed Nr is increased is determined based on the state of the auxiliary transmission mechanism 43. The reduction of the engine speed Nr continues until the load factor L becomes equal to or higher than the light load value L4 (L3) (T6), and after T6, the engine speed Nr remains at the reduced engine speed at T6 and the vehicle speed V is maintained at the target vehicle speed Vs.

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

  For example, as shown in FIG. 12, the engine speed Nr is increased from T7, and the engine speed is maintained at N1 from the time (T8) raised to the engine speed N1. When the engine speed upper limit value Nmax decreases from Nmax1 to Nmax2 by operating the engine speed change setting dial 82, the engine speed Nr becomes Nmax2 by driving the engine speed change actuator 93 from T9. Decrease gradually until. When the engine speed Nr reaches Nmax2 at T10, the engine speed and the vehicle speed control are performed again.

  When the engine speed setting means 70 is operated during engine speed control and vehicle speed control to change the target engine speed Ns, the engine speed Nr at that time is increased or decreased by the target engine speed Ns. Is increased or decreased. For example, as shown in FIG. 13, the engine speed Nr is increased from T11, and the engine speed Nr is maintained at N2 from the time (T12) when the engine speed Nr is increased from the target engine speed Ns1 to N2. If the target engine speed Ns is increased from Ns1 to Ns2 by operating the engine speed setting means 70 at T13, the engine speed change actuator 93 is driven to start the engine rotation from T13. The number Nr is gradually increased by the difference d between Ns2 and Ns1. When the engine speed Nr reaches N2 + d at T14, the engine speed Nr is maintained as it is.

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

  In addition, when the control selection switch is changed from “on” to “off” by operating the control selection switch 80 during engine speed and vehicle speed control, the engine rotation speed changing actuator 93 and the transmission actuator 91 By driving, the engine speed Nr and the vehicle speed V are gradually returned to the target engine speed Ns and the target vehicle speed Vs.

  As described above, the tractor 1 includes the engine speed detecting means 71, the engine speed setting means 70, the engine speed changing actuator 93, the vehicle speed detecting means 61, the continuously variable transmission 41a, and the continuously variable transmission 41. A tractor comprising: a gear shift actuator 91 for shifting gears 41a; a control device 100 as load detection means; an engine rotational speed detection means 71; an output detection means 74; and the control device 100 for controlling the engine rotational speed and the vehicle speed When the engine load factor L becomes larger than the set heavy load value L1, the engine speed Nr is increased while maintaining the vehicle speed V constant, and the engine speed Nr is increased to the engine speed upper limit value Nmax. When the engine load factor L becomes larger than the set heavy load value L2, the vehicle speed V is decreased. When the engine load factor L becomes smaller than the set light load value L4, the engine speed Nr is maintained while maintaining the vehicle speed V constant. A light load mode is provided to control the engine speed change actuator 93 and the speed change actuator 91 so as to reduce the speed. With this configuration, when heavy load mode is selected, engine speed Nr can be increased, vehicle speed V can be decreased, engine stall can be prevented, and work efficiency can be improved. . When the light load mode is selected at light load, the engine speed change actuator 93 can decrease the engine speed Nr and travel with low fuel consumption.

  In addition, the engine speed change amount setting dial 82 and the vehicle speed change amount setting dial 83 capable of arbitrarily changing the change amount of the engine speed Nr and the change amount of the vehicle speed V in the heavy load mode and the light load mode It is. By configuring in this way, it is possible to change the amount of change of the engine speed Nr and the amount of change of the vehicle speed V in each mode, respectively, according to the preference of the user, the work type and the state of the farmland, It can be improved.

  Further, the mode operation switch 81 is provided to perform on / off setting of control of the engine speed change actuator 93 by performing on / off setting in the heavy load mode or the light load mode. By configuring in this manner, 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.

  The light load value L3 and the light load value L4 set as the heavy load value L1 and the heavy load value L2 in the heavy load mode and the light load mode can be changed by the threshold setting dial 84. By configuring in this manner, the threshold value in each mode can be changed according to the preference of the user, the work mode, and the state of the farmland, and the finish of the work can be improved and the engine stall can be prevented.

  The auxiliary transmission mechanism 43 is provided as setting means for setting the engine speed changing speed and the vehicle speed changing speed in the heavy load mode and the light load mode. By configuring in this manner, the threshold value in each mode can be changed according to the preference of the user, the work mode, and the state of the farmland, and the finish of the work can be improved and the engine stall can be prevented.

  In addition, the display unit 85 is provided to display the heavy load mode and the light load mode. By configuring in this manner, 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 Speed change amount setting dial 84 Threshold setting dial 85 Display 91 Variable speed actuator 93 Engine speed change actuator 100 Controller

Claims (2)

A controller for controlling an engine speed and a vehicle speed;
An engine rotational speed change amount setting means capable of setting an allowable amount of the engine rotational speed to be decreased from the engine rotational speed set by the accelerator lever;
The controller is
When the load on the engine is smaller than a predetermined load value, control is performed to reduce the engine speed within the allowable range while maintaining the vehicle speed constant,
By operating the selection means for selecting "on" or "off" of the engine speed control and the vehicle speed control while executing the control, the engine speed control and the vehicle speed control are switched off from "on". When it is changed to “,” the working vehicle is characterized by returning the engine speed to the engine speed set by the accelerator lever. The controller is
When the mode which allows the reduction of the engine speed is executed and the load of the engine is lighter than the predetermined load value, the engine speed is set to the above-mentioned allowable amount while maintaining the vehicle speed constant . The work vehicle according to claim 1, wherein control to decrease within a range is performed.

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