JP2011127573A - Tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compose a tractor preventing wastefully consuming fuel during light load operation. <P>SOLUTION: This tractor includes a fuel supply control means 51 supplying an engine E with fuel corresponding to operation of an accelerator pedal 35, a fuel limit control means 52 supplying fuel less than an upper limit value artificially set by a fuel supply quantity set dial 41, taking precedence over fuel supply by the fuel supply control means 51, and a fuel forced supply means 53 allowing supply of fuel exceeding the upper limit value only when overload is applied. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tractor provided with fuel supply control means for supplying fuel corresponding to an operation position of an accelerator operating tool to an engine, and more particularly to a technique for limiting engine rotation.

  As related to the tractor configured as described above, Patent Document 1 describes switching between three modes of a traveling mode, a normal working mode, and a heavy working mode in relation to the engine speed and output torque. What can be done is shown.

  Specifically, in the travel mode, droop control that allows fluctuations in the engine speed is performed, in the normal work mode, isochronous control is performed in which the engine speed remains constant even when the load fluctuates, and in the heavy work mode, normal work is performed. In addition to the isochronous control that keeps the engine speed constant as in the mode, it is described that the control is performed to increase the speed when the engine is close to the load limit.

JP 2009-132310 A

  Taking a tractor as an example, for example, in a light load operation that only moves the vehicle body, it is not necessary to increase the engine rotation, and the engine can be driven at a low speed. Moreover, even if the output of the engine is larger than that for moving the vehicle body, high-speed rotation of the engine is not required for relatively light load operations such as sowing work and fertilizer application.

  In contrast to the current situation, a tractor equipped with an accelerator pedal can arbitrarily set the engine rotation control in response to the operation of the accelerator pedal, so if the accelerator pedal is depressed greatly when moving the vehicle body The engine was rotated at high speed. Thus, when the engine is rotated at a high speed, the amount of fuel consumption inevitably increases, leading to a reduction in fuel consumption. Therefore, it is conceivable to limit the amount of fuel supplied, but simply limiting the amount supplied can lead to engine stall when a large load is applied, and there is room for improvement.

  An object of the present invention is to rationally configure a tractor that does not waste fuel during light load work and can eliminate the inconvenience of engine stall.

A feature of the present invention is a tractor provided with fuel supply control means for supplying fuel corresponding to an operation position of an accelerator operating tool to an engine,
An upper limit value of fuel that can be supplied by the fuel supply control means is set, and when the accelerator operating tool is operated to a position for setting fuel supply in an amount exceeding the upper limit value, the fuel of the upper limit value is A fuel restriction control means for supplying the engine,
In a situation where the fuel supply amount is restricted by the fuel restriction control means, when the engine load exceeds a set value, the fuel that allows the fuel supply amount to increase in preference to the restriction of the fuel restriction control means The forced supply means is provided.

  According to this configuration, when the accelerator operation tool is operated by setting the upper limit value of the fuel supply amount by the fuel restriction control means, when the operation position is at the fuel supply position less than the upper limit value. The fuel supply corresponding to the operation position of the accelerator operating tool can be performed. Further, when the operation position of the accelerator operating tool is a fuel supply position exceeding the upper limit value, the fuel of the upper limit value set by the fuel restriction control means is supplied to the engine, and as a result, the amount of fuel supply Does not exceed the upper limit. Further, when the upper limit value of the fuel supply amount is set and the engine load exceeds the set value, the fuel limit control means is prioritized over the fuel limit control means without any manual operation. The forcible supply means increases the amount of fuel supplied and does not cause engine stall. As a result, a tractor has been constructed that does not waste fuel during light load work and can eliminate the inconvenience of engine stall.

  According to the present invention, the fuel restriction control means can arbitrarily set the upper limit value corresponding to the setting position of the artificial operation tool, and perform selection of setting and release of the upper limit value by operating the artificial operation tool. Also good.

  According to this, it is possible to set an upper limit value corresponding to the setting position of the artificial operation tool, and it is possible to set and release the upper limit value by operating this artificial operation tool, and to set the upper limit value of the fuel supplied to the engine And a state in which fuel is supplied without setting an upper limit for the engine.

  The present invention comprises a working device discriminating means for discriminating the type of working device provided in the vehicle body, and the fuel restriction control means sets an upper limit value corresponding to the working device discriminated by the working device discriminating means. Also good.

  According to this, the upper limit value is automatically set according to the type of work device provided in the vehicle body. For example, when the engine load is relatively low during work by the work device, the upper limit value is set low. However, when the engine load of work by the work device is relatively high, by setting a high upper limit value, it becomes possible to set an appropriate upper limit value corresponding to the type of work device, which is operated manually. Save time and effort.

It is the whole tractor side view. It is a perspective view which shows the raising / lowering operation system of a rotary tilling apparatus. It is a top view of the operation part of a tractor. It is a block circuit diagram which shows the control system of a tractor. It is a block diagram which shows the control system of an engine. It is a flowchart of fuel supply control. FIG. 5 is a graph showing the relationship between torque / fuel injection amount and engine speed. It is a block diagram which shows the control system of the engine of another embodiment (a).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
〔overall structure〕
As shown in FIG. 1, a driving unit Ac is disposed at a central position of a vehicle body A having a pair of left and right front wheels 1 and a pair of left and right rear wheels 2 as a traveling device, and can be raised and lowered at the rear end of the vehicle body A. In addition, a tractor is configured by connecting a rotary tiller R as a working device in a freely rolling manner.

  This tractor includes a water-cooled diesel engine E (hereinafter abbreviated as engine E) in an engine hood at the front position of the vehicle body A, and extends from the lower side to the rear end of the driving unit Ac at the center position of the vehicle body A. A mission case M is provided at the site. The transmission case M includes a transmission Mt having a function of shifting the driving force of the engine E and transmitting the driving force to the front wheels 1 and the rear wheels 2, and transmits the shifting driving force to the PTO shaft 3 as an output shaft at the rear end of the vehicle body. .

  As shown in FIG. 4, the engine E includes a common rail fuel injection device that electronically controls the fuel injection amount and the injection timing. The fuel injection device includes a supply pump 6 that pumps fuel stored in the fuel tank 5, a common rail 7 that accumulates the pumped fuel, and a plurality of electronically controlled types that inject the accumulated fuel into a combustion chamber (not shown). An injector 8, a pressure sensor 9 that detects the internal pressure of the common rail 7, and a pickup type rotation sensor 10 that measures the rotational speed of the engine E are provided. The engine E may be a gasoline engine.

  Although not shown in the drawings, the above-described transmission Mt performs the disengagement operation of the transmission hydraulic clutch during the shift operation of the operator, and then shifts the transmission gear by the operation of the hydraulic shift cylinder as the actuator. Then, the hydraulic clutch is engaged, and these operations are executed sequentially within a short period of time, thereby realizing a shift without the operator manually disengaging the main clutch. In this transmission Mt, a synchromesh gear transmission system having a shifter that is operated by the driving force of the shift cylinder, a shift cylinder that is operated by hydraulic pressure, and a hydraulic clutch that is operated by hydraulic pressure are linked to each other. It has a pilot hydraulic system.

  The transmission device Mt for the tractor according to the present invention is not limited to the gear shift operation performed by the shift cylinder as described above, and includes a hydraulic clutch (acting as an actuator) for each gear transmission of the transmission system. It may be provided with a speed change structure that takes out a speed change driving force from the gear speed change portion by selectively entering and operating any one of the plurality of hydraulic clutches during the speed change operation of the operator.

  As shown in FIGS. 1 and 2, a pair of left and right lift arms 12 whose rocking ends are moved up and down by the operation of the lift cylinder 11 are provided at the upper end of the transmission case M at the rear end of the vehicle body A. The base end position of 12 is provided with a lift arm sensor 12S that measures a swing angle. The rotary tiller R is connected to the rear end of the vehicle body A via a three-point link mechanism including a single top link 13 and a pair of left and right lower links 14. The left and right lower links 14 and the left and right lift arms 12 are connected by a lift rod 15, and a double-acting rolling cylinder 15C is interposed in one of the left and right lift rods 15 at a position parallel to this. A stroke sensor 15S for measuring the amount of expansion / contraction of the rolling cylinder 15C is provided.

  The rotary tiller R includes a horizontal frame 17 to which the driving force from the PTO shaft 3 described above is transmitted through a transmission shaft 16 having a universal joint, a transmission case 18 to which power is transmitted from the horizontal frame 17, and the transmission. A rotary shaft 19 that receives power from the case 18 and rotates around the drive shaft core in a lateral orientation is provided. The rotary shaft 19 is provided with a number of tilling claws 20, and a rear cover 22 is provided at a rear position of the upper cover 21 of the rotary tiller R so as to be swingable around a horizontal swing shaft core. ing.

  The upper cover 21 is provided with a cover sensor 23 as a tilling depth detecting means for detecting the tilling depth from the swinging amount of the rear cover 22. A rolling angle sensor 24 that detects the rolling angle of the vehicle body A is provided at the rear end position of the vehicle body A.

  As shown in FIGS. 1 and 3, the driving unit Ac includes a cabin 30 having a side glass wall and an upper roof, and a driving seat 31 on which an operator sits. . At the front position of the driver's seat 31, a steering wheel 32 that steers the front wheel 1, an accelerator lever 33 as an accelerator operating tool that sets the rotation speed of the engine E, and a forcible lift of the rotary tiller R are provided. A forced raising / lowering lever 34 is disposed, and an accelerator pedal 35 as an accelerator operating tool is disposed at a lower position. At the side position of the driver's seat 31, there are provided a main transmission lever 36 as a speed change operation tool for setting the traveling speed, and a position lever 37 for controlling the raising / lowering of the rotary tiller R, and automatic tilling of the rotary tiller R. Set the tilling depth setting dial 38 for setting the tilling depth during depth control, the upper limit setting dial 39 for setting the target upper limit (lifting position) of the rotary tiller R during forced ascent, and the target rolling angle of the rotary tiller R And a fuel supply amount setting dial 41 as an artificial operation tool for arbitrarily setting an upper limit value of fuel supplied to the engine E.

  The accelerator lever 33 has a friction holding structure so that the rotation speed of the engine E is arbitrarily set and held by manual operation, and the accelerator pedal 35 arbitrarily sets the rotation speed of the engine E by a depression operation. It has a spring biasing structure so as to return to the low speed rotation side during operation.

  The position lever 37 is a swing operation type and has a structure that can be frictionally held at an arbitrary operation position. The position of the rotary tiller R is raised by raising the rear side of the vehicle body (the swing end of the lift arm 12 is raised). ), The rotary tiller R is lowered (the swing end of the lift arm 12 is lowered) by the operation to the rear of the vehicle body, and the height of the rotary tiller R is set to the height of the vehicle corresponding to the swing position. To achieve position control. In particular, the shift to the automatic tilling depth control is realized by operating the position lever 37 to the operation end on the front side (most lowered side).

  The forcible elevating lever 34 can be operated to an upper ascending operation position with respect to the neutral position and a lower ascending operation position with respect to the neutral position, and can be held in the neutral position in a non-operating state. It is energized. This forced elevating lever 34 is a target in which the rotary tiller R is set with the upper limit setting dial 39 in preference to the automatic tilling control when the operator operates the lifting operation position even for a short time during the automatic tilling control. Realizes forced ascending control that raises to the upper limit and stops. Further, in this raised state, when the operator operates the descent operation position even for a short time, the rotary tiller R is lowered to shift to automatic tilling control.

  The working depth setting dial 38 arbitrarily sets a target working depth in the automatic working depth control by rotating operation. In the automatic working depth control, a cover sensor is set to the target working depth set by the working depth setting dial 38. The lift cylinder 11 is controlled so that the tilling depth of the rotary tiller R detected at 23 is maintained.

  The rolling angle setting dial 40 arbitrarily sets a target rolling angle in the rolling control by a rotation operation. In the rolling control, the rotary tilling device is based on the measurement result of the stroke sensor 15S and the measurement result of the rolling angle sensor 24. The R rolling angle is calculated, and the rolling cylinder 15C is controlled to extend and contract so that the calculated ground rolling angle is maintained at the target rolling angle.

  The fuel supply amount setting dial 41 arbitrarily sets the upper limit value of the fuel to be supplied to the engine E in preference to the setting of the accelerator lever 33 and the accelerator pedal 35 by rotating operation, and selects whether to set or cancel the upper limit value. As shown in FIGS. 4 and 5, it is possible to operate an OFF area and a setting area adjacent to the OFF area. The upper limit value is set by operating the fuel supply amount setting dial 41 in the setting area. In the area below the upper limit value, fuel supply corresponding to the setting of the accelerator lever 33 and the accelerator pedal 35 is enabled, and the OFF area. When set to, the upper limit value is canceled (the upper limit value is not set). In the setting region, the fuel limit amount (limit rate) is low in the region close to the OFF region, and the fuel limit amount (limit rate) is higher in the region away from the OFF region, and the limit amount is maximum at the maximum limit position. .

  The main transmission lever 36 is configured as a swing operation type and can be held at an arbitrary shift position, and corresponds to the shift position by controlling the shift cylinder and the hydraulic clutch of the transmission Mt corresponding to the shift position. A gear stage (shift state) is created.

  Thus, the tractor can perform position control, automatic tilling control, and rolling control, and can perform shift control corresponding to the operation of the main shift lever 36.

  In particular, the tractor includes a control system that is realized by control for electrically setting the upper limit value of the fuel supply amount based on the setting of the fuel supply amount setting dial 41. Is described below.

[Control configuration]
As shown in FIG. 4, this tractor controls the engine E with a microprocessor, a memory and the like so as to control the engine E, and controls the raising and lowering and rolling of the rotary tiller R to control the transmission Mt. The main ECU 60 having a microprocessor, a memory, and the like is provided, and a signal system for mutually accessing information by in-vehicle communication such as CAN (Controller Area Network) communication between the engine ECU 50 and the main ECU 60 is provided. It is configured.

  The engine ECU 50 has a fuel supply control means 51 for supplying an amount of fuel corresponding to a target rotation speed set by the accelerator lever 33 or the accelerator pedal 35 for the rotation speed of the engine E, and fuel supply by the fuel supply control means 51. The fuel limit control means 52 that allows the supply of fuel in an amount less than the upper limit value set by the fuel supply amount setting dial 41 in preference to the supply, and the fuel supply control in the fuel limit control means 52 has priority over the fuel supply restriction. And a forced fuel supply means 53 that allows an increase in the supply amount. When the accelerator lever 33 and the accelerator pedal 35 are operated at the same time, the setting on the fuel supply side (high speed side) is acquired as the target rotation speed.

  The main ECU 60 includes a position control means 61 that realizes position control, an automatic tilling depth control means 62 that realizes automatic tilling control, and a forced lifting control means 63 that realizes forced raising control and forced lowering control of the rotary tiller R. And a rolling control means 64 for realizing the rolling control of the rotary tiller R and a shift control means 65 for realizing the speed change of the transmission Mt.

  Fuel supply control means 51, fuel restriction control means 52, fuel forced supply means 53, position control means 61, automatic tilling depth control means 62, forced elevating control means 63, rolling control means 64, The shift control means 65 is constituted by software, but these may be constituted by a combination of software and hardware, or may be constituted only by hardware.

  The engine ECU 50 measures the rotational speed of the engine E, and a potentiometer-type lever sensor 33S that detects the accelerator set position by the accelerator lever 33, a potentiometer-type pedal sensor 35S that detects the accelerator set position by the accelerator pedal 35, and the like. Signals from a rotation sensor 10 such as a pickup type, the pressure sensor 9 that detects the internal pressure of the common rail 7 described above, and a potentiometer type dial sensor 41S that detects the set position of the fuel supply amount setting dial 41 are input.

  The main ECU 60 includes a lift switch 34S that detects the operation of the forced lift lever 34, a position sensor 37S such as a potentiometer that detects the operation position of the position lever 37, and a potentiometer or rotary that detects the set position of the main transmission lever 36. A shift position sensor 36S, such as a switch type, a tilling depth setting device 38S, such as a potentiometer type, which detects the setting position of the depth setting dial 38, and an upper limit setting device 39S, such as a potentiometer type, which detects the operation position of the upper limit setting dial 39. A potentiometer type rolling arm setter 40S for detecting the operating position of the rolling angle setting dial 40, a potentiometer type lift arm sensor 12S, a potentiometer type stroke sensor 15S, and a potentiometer type cover sensor 23. When Luo signal is input.

  Further, the main ECU 60 includes an electromagnetic lift control valve 11V for supplying and discharging hydraulic oil to and from the lift cylinder 11, an electromagnetic rolling control valve 15V for supplying and discharging hydraulic oil to and from the rolling cylinder 15C, A control signal is output to the device Mt.

  In the engine ECU 50, the set position of the accelerator lever 33 is acquired from the signal of the lever sensor 33S, the operation position of the accelerator pedal 35 is acquired from the signal of the pedal sensor 35S, and the fuel supply control means 51 performs isochronous control or droop control. In response to this, control is performed to set the target rotational speed by controlling the fuel injection amount and injection timing. When the accelerator pedal 35 is depressed while the accelerator lever 33 is set to an arbitrary position, control for increasing the rotational speed of the engine E is performed only when the set position of the accelerator lever 33 is exceeded.

  In the main ECU 60, when the position control means 61 executes position control, the operation position of the position lever 37 is acquired by the position sensor 37S, the acquired position is set to the target height, and the lift arm sensor 12S. Thus, the height of the rotary tiller R with respect to the vehicle body is detected, and the lift control valve 11V is operated to operate the lift arm 12 so that the height with respect to the vehicle body matches the target height.

  Further, when the automatic tilling depth control means 62 executes automatic tilling depth control, the setting position of the tilling depth setting dial 38 is acquired by the tilling depth setting device 38S, and the position thus acquired is set as the target tilling depth. Then, the plowing depth (actual plowing depth) of the rotary plowing device R is obtained from the detection information of the cover sensor 23, and the elevating control valve 11V is operated so that this plowing depth (actual plowing depth) matches the target plowing depth. Control for operating the lift arm 12 is performed.

  When the rolling control means 64 executes the rolling control, the setting position of the rolling angle setting dial 40 is acquired by the rolling angle setting device 40S and set to the target rolling angle, and the measurement result of the stroke sensor 15S and the rolling angle are set. Based on the measurement result of the sensor 24, the ground rolling angle of the rotary tiller R is obtained by calculation, and the rolling cylinder 15C is operated by operating the rolling control valve 15V so that the ground rolling angle matches the target rolling angle. Control is performed.

  Further, when the elevating switch 34S acquires that the forced elevating lever 34 has been operated to the forced elevating position during execution of the automatic tilling control, the forced elevating control means 63 sets the upper limit setting dial 39 to the upper limit setting device. Forcibly ascending in such a form that the lift arm 12 is operated by operating the lift control valve 11V so that the height with respect to the vehicle body detected by the lift arm sensor 12S matches the target upper limit. Control is performed.

  Thus, when the forcible elevating lever 34 is operated to the forcibly lowered position while the rotary tiller R is in the ascending position (target upper limit) by the forcibly raising control, the forcibly raising and lowering control means 63 is detected by the lift arm sensor 12S. The forced lowering control is performed in which the height of the vehicle body to be lowered is lowered to the lower limit, the automatic plowing depth control is shifted to operate the elevation control valve 11V.

  In addition, since the rear end of the rear cover 22 hangs down at the timing of starting the forced lowering control, since the rotary tiller R is controlled to be lowered by shifting to the automatic tilling control at this time, the forced lifting is performed. Forcibly descending control may be realized by shifting to automatic tilling control at the timing when the lever 34 is operated to the forcibly descending position.

[Control form]
This control form is shown in the flowchart of FIG. 6, and the flow of information in this control is shown in FIG. 5. In FIG. 7, the amount of fuel supplied to the engine E (fuel injection amount / torque) during the control and the engine The figure which plotted the relationship with the rotation speed (rotation speed) is shown.

  In this control, when the fuel supply amount setting dial 41 is in the OFF region, the fuel supply control means 51 acquires the high speed side of the set positions of the accelerator lever 33 and the accelerator pedal 35 as the accelerator set position. The fuel supply control means 51 controls the amount of fuel ejected by the injector 8 so that the fuel corresponding to the accelerator position is supplied to the engine E (steps # 101 and # 102).

  When the fuel supply amount setting dial 41 is not in the OFF region, the fuel restriction control means 52 acquires from the dial sensor 41S the setting position of the fuel supply amount setting dial 41 as the upper limit position, and the fuel supply control means 51 The set position of the accelerator lever 33 is acquired from the lever sensor 33S, and the set position of the accelerator pedal 35 is acquired from the pedal sensor 35S (steps # 101, # 103, and # 104).

  Next, when the accelerator setting position does not exceed the upper limit value, the fuel injection amount by the injector 8 is set so as to supply the fuel corresponding to the accelerator setting position (steps # 105 and # 102). . When the accelerator setting position exceeds the upper limit value, the forced fuel supply means 53 acquires the engine load, and when the forced fuel supply means 53 determines that the engine load is less than the set value. The fuel injection amount by the injector 8 is maintained at the upper limit (steps # 105 to # 108).

  Further, when it is determined that the engine load exceeds the set value when the accelerator set position exceeds the upper limit value, the fuel injection amount by the injector 8 is set so that the fuel corresponding to the accelerator set position is supplied. Setting is performed (# 105 to # 108 steps and # 102 steps). It should be noted that the engine load set value is set to a load close to the value that leads to engine stall, and when the engine load set value is reached, the engine injection can be avoided by releasing the restriction on the fuel injection amount. I have to.

  The engine load is determined by the forced fuel supply means 53 based on the accelerator setting position and a signal from the rotation sensor 10. In order to determine the engine load, the forced fuel supply means 53 includes a table for obtaining a load from the relationship between the accelerator set position and the engine speed (rotation speed), or the accelerator set position and the engine speed (rotation speed). An arithmetic expression for obtaining the load from the relationship is provided in advance. A torque sensor or the like for measuring the engine load may be provided.

  As a processing form of the forced fuel supply means 53, when a preset engine load is exceeded, fuel supply corresponding to the accelerator operation position is permitted. However, for example, engine stall can be eliminated. The control mode may be set so as to allow an increase in the amount of fuel.

  As shown in FIG. 7, when either the accelerator lever 33 or the accelerator pedal 35 is set to the maximum accelerator setting position, torque according to the characteristic graph Y along the full load curve X (fuel injection amount) ) And the rotational speed. When the upper limit value is set to 50% by the fuel supply amount setting dial 41, the relationship between the torque (fuel injection amount) and the rotational speed according to the graph Z in FIG.

  The upper limit value (supply rate of fuel that can be supplied) when the fuel supply amount setting dial 41 is set to the maximum limit position in the setting region may not be a specific value. For example, the accelerator lever 33 and the accelerator pedal 35 may be used. For example, it can be set to 50% of the maximum value that can be set.

[Operations and effects of the embodiment]
As described above, in the working machine of the present invention, when the vehicle body A is simply moved or when a light load operation such as sowing work or fertilizer application is performed, the fuel supply amount setting dial 41 sets the upper limit value of the fuel supply. For example, when the accelerator pedal 35 is largely depressed, the fuel supply is limited so that the engine E does not rotate unnecessarily at high speed. Can be wasted. That is, the upper limit of the fuel supply amount can be arbitrarily set by the fuel supply amount setting dial 41.

  Even if the work is a light load that only moves the vehicle body A, even if the load increases and the engine stalls, such as when climbing on a slope that the operator does not expect, the accelerator It is also possible to automatically avoid engine stalls by allowing fuel supply corresponding to the set position.

[Another embodiment]
The present invention may be configured as follows in addition to the embodiment described above.

(A) The engine ECU 50 is configured to automatically set the upper limit value of the fuel supplied to the engine E in correspondence with the work device provided in the vehicle body. Specifically, instead of the fuel supply amount setting dial 41 described in the above-described embodiment, a construction is provided with a work device discrimination means 45 as shown in FIG. The work device determination means 45 specifies the type of the work device provided in the vehicle body A, and outputs information that can specify the work device to the engine ECU 50.

  In the engine ECU 50, the fuel limit control means 52 sets an upper limit value corresponding to the work device based on information that can identify the work device, and even when the accelerator set position exceeds the upper limit position, the fuel injection by the injector 8 is performed. Control is performed to maintain the amount at the upper limit value, and fuel corresponding to the accelerator set position is supplied only when it is determined that the load acting on the engine E exceeds the set value. The upper limit set automatically is set higher than the upper limit set for the rotary tiller, and the upper limit set for the plow is set higher, and the upper limit is set lowest when no working device is provided. The In this other embodiment, the processes other than the process of automatically setting the upper limit value are the same as those in the above-described embodiment, and therefore a detailed description of the control mode is omitted.

  In addition, a rotary tiller, a plow, a seeding device, and the like are assumed as the working device, and the processing for identifying the working device by the working device discriminating means 45 is based on signal values from sensors used when working each working device. Thus, it is conceivable to specify a work device by automatic processing, such as specifying a work device or specifying a work device based on a signal from a switch provided at a connection portion of the work device. Although it is different from this, since an operator operates switches corresponding to the work device at the time of work, the work device may be specified based on the operation of such switches. Further, the switch for specifying the work device may be manually operated, and the work device may be directly specified based on this operation.

(B) A push operation type switch may be provided as an artificial operation tool for setting an upper limit value of the fuel supply amount. Specifically, a plurality of push operation type switches may be provided, and an upper limit value corresponding to the selected switch may be set by selectively operating any of the plurality of switches. As a different configuration, one push operation type switch may be provided and the upper limit value may be changed depending on the number of times the switch is depressed.

  The present invention can be used for all work vehicles that electrically control engine rotation in addition to tractors.

33 Accelerator (Accelerator lever)
35 Accelerator (Accelerator pedal)
41 Artificial operation tool (fuel supply amount setting dial)
45 Working device discrimination means 51 Fuel supply control means 52 Fuel limit control means 53 Fuel forced supply means A Car body E Engine

Claims (3)

A tractor provided with fuel supply control means for supplying fuel corresponding to the operation position of the accelerator operating tool to the engine,
An upper limit value of fuel that can be supplied by the fuel supply control means is set, and when the accelerator operating tool is operated to a position for setting fuel supply in an amount exceeding the upper limit value, the fuel of the upper limit value is A fuel restriction control means for supplying the engine,
In a situation where the fuel supply amount is restricted by the fuel restriction control means, when the engine load exceeds a set value, the fuel that allows the fuel supply amount to increase in preference to the restriction of the fuel restriction control means A tractor equipped with forced supply means.   2. The fuel limit control means according to claim 1, wherein the upper limit value can be arbitrarily set in accordance with the setting position of the artificial operation tool, and the upper limit value can be set and canceled by operating the artificial operation tool. Tractor.   3. A working device discriminating means for discriminating the type of working device provided in the vehicle body, wherein the fuel restriction control means sets an upper limit value corresponding to the working device discriminated by the working device discriminating means. The described tractor.

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