JP2008133896A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel consumption and prevent a deterioration in working efficiency by requiring no complicated control structures by allowing a simple manual operation during work in constant speed travel. <P>SOLUTION: The working vehicle is equipped with an energy-saving mode selecting operation tool 50 for outputting a control signal to an engine rotation speed control device 31 so as to reduce the engine rotation speed by a prescribed amount during working travel at set rotation speed by a rotation speed keeping mechanism for carrying out working travel while keeping engine rotation speed constant, and a speed control means 101 for operating a change gear 4 so as to make the reduction rate of travelling speed less than that of rotation speed based on the detection of operation of the energy-saving mode selecting operation tool 50. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a work vehicle in which an engine is controlled so as to maintain a rated rotation, such as a tractor equipped with a work device such as a rotary tiller.

As a work vehicle equipped with a mechanism that maintains the engine speed at the rated speed, in recent years it is not only intended to simply maintain the engine speed at the rated speed close to the maximum engine output, but also to improve fuel efficiency. Is structured as follows.
That is, a change in engine load is detected by an electronically controlled governor, a change in engine speed is detected using an engine speed detector, and a difference from the maximum torque that the engine can output at a set speed is determined in advance. The difference between the calculated and stored optimum fuel consumption line is calculated, and the engine speed and the running speed are automatically controlled so as to obtain the engine speed and tillage speed along the optimum fuel consumption line. (For example, refer patent document 1).

JP 2003-129879 A (paragraphs “0037”, “0039”, “0042”, FIGS. 5 and 6)

  In a work vehicle such as a tractor that works while maintaining a constant engine speed, engine stall may occur in advance if the engine speed is too low, because engine stall may occur depending on the magnitude of load fluctuation. However, when the work load is light, the engine speed may be clearly too high, resulting in poor fuel efficiency.

Therefore, as in the technique disclosed in Patent Document 1, the engine speed is controlled and the traveling speed is controlled so as to obtain the engine speed and the tilling speed along the optimum fuel consumption line. If it is adopted, the fuel efficiency of the work vehicle can be improved automatically without any manual operation. Therefore, although it is effective in improving the fuel efficiency, there are the following problems.
In other words, since control is performed by constantly monitoring fluctuations in engine load and engine speed, many high-precision detectors and high-performance processing control are required to perform control with good responsiveness. There is a tendency to increase the cost of the control system. Also, if fuel efficiency priority control is performed, the traveling speed will drop considerably at high loads and the overall work time will be extended, or the traveling speed will become too fast at light loads. Control is required, and the control system tends to become more complicated.

  An object of the present invention is to improve fuel efficiency and suppress reduction in work efficiency without requiring a complicated control structure by allowing simple human operation to be taken into account when performing work at a constant speed. It is to provide a work vehicle that can be used.

The technical means of the present invention taken in order to achieve the above object has the following structural features and operational effects.
[Solution 1]
In a work vehicle equipped with a rotation speed maintenance mechanism for keeping the engine speed constant and running the work,
An energy-saving mode selection operation tool for outputting a control signal to the engine speed control device so as to reduce the engine speed by a predetermined amount during work traveling at a set speed by the speed maintaining mechanism;
Based on the detection that the energy saving mode selection operation tool has been operated, a speed control means is provided for operating the transmission so that the rate of decrease in travel speed is less than the rate of decrease in engine speed.

[Operation and effect of invention according to Solution 1]
According to the configuration shown in the above solution 1, the energy saving that outputs the control signal to the engine speed control device so as to reduce the engine speed by a predetermined amount during the work traveling at the set speed by the speed maintaining mechanism. Since the mode selection operation tool is provided, it is possible to perform the work in the energy saving mode with the improvement of the fuel consumption and the suppression of the reduction of the work efficiency only by performing a simple manual operation.
In other words, if it is performed by automatic control, it becomes a complicated control form, but as a human judgment, it is a process that can be judged easily from engine sound etc., but it is a human operation to judge whether control should be performed or not. As a result, the entire control system can be remarkably simplified.
The shift control for suppressing the decrease in the traveling speed accompanying the decrease in the engine speed after the start of the control is a complicated operation requiring a certain level of skill as a manual operation. Thus, it can be easily performed by the speed control means.

[Solution 2]
According to a second aspect of the present invention, in the work vehicle according to the first aspect, the engine speed reduced by the energy saving mode selection operation tool is such that the work speed of the work device driven by the PTO shaft is the lower limit of the proper work speed range. The speed is reduced by the energy-saving mode selection operation tool so that the speed does not fall below.

[Operation and effect of invention according to Solution 2]
According to the configuration shown in Solution 2, the reduction amount of the engine speed by the energy saving mode selection operation tool is set so that the work speed of the work device driven by the PTO shaft does not fall below the lower limit of the appropriate work speed range. Therefore, there is an advantage that it is possible to suppress the reduction of the processing capacity by the working device while improving the fuel consumption by reducing the engine speed with a simple operation.

[Solution 3]
According to a third aspect of the present invention, in the work vehicle according to the first or second aspect, a work speed for outputting a speed increase command to the PTO transmission based on detection that the energy saving mode selection operation tool has been operated. It is characterized in that it has a control means.

[Operation and effect of invention according to Solution 3]
According to the configuration shown in the solution means 3, by providing the work speed control means for outputting a speed increase command to the PTO transmission, the engine speed is reduced and the traveling speed is reduced to some extent. However, the work speed of the work device can be reduced so that the work can be performed with little decrease, which is effective when priority is given to work performance over work time.

Hereinafter, an example of an embodiment of the present invention will be described based on the drawings.
〔overall structure〕
FIG. 1 shows an entire side surface of a tractor which is an example of a work vehicle. This tractor has a clutch housing 3 connected to a rear end portion of an engine 2 mounted and supported on a front frame 1. 3 is connected to a hydrostatic continuously variable transmission (an example of a hydraulic continuously variable transmission) 4 employed as a main transmission, and a transmission case is connected to the rear end of the hydrostatic continuously variable transmission 4. 5 is connected to form a body frame 6, a driving part is formed in the front half of the body frame 6, a boarding operation part 7 is formed in the latter half of the body frame 6, A pair of left and right front wheels 8 for steering that are configured to be able to transmit engine power are provided, and a pair of left and right rear wheels 9 that are configured to be able to transmit engine power are provided in the rear lower part of the body frame 6. Of the fuselage frame 6 A pair of left and right lift arms 10 and a link mechanism 11 that enable connection of various work devices (not shown) are provided at the end, and work such as a rotary tillage device (not shown) connected and connected via them. A power take-off shaft 12 is provided that allows engine power to be removed from the device.

  As shown in FIGS. 1 and 2, the power from the engine 2 is transmitted to a hydrostatic continuously variable transmission 4 via a dry single plate main clutch 13 built in a clutch housing 3, and this hydrostatic type. A gear-type transmission that is employed as a sub-transmission device in the transmission case 5 as power for driving the power after shifting by the hydrostatic continuously variable transmission 4 output from the motor shaft 4a of the continuously variable transmission 4 14 is transmitted to the front wheel clutch 15 or the rear wheel differential device 16 and output from the front wheel clutch 15 through the front wheel transmission shaft 17 and the front wheel differential device 18 for driving the front wheels. The power transmitted to the left and right front wheels 8 and output from the rear wheel differential 16 is transmitted to the left and right rear wheels 9 for driving the rear wheels. On the other hand, the non-shifting power output from the pump shaft 4b of the hydrostatic continuously variable transmission 4 is taken out through the working clutch 19 and the PTO transmission 20 incorporated in the transmission case 5 as working power. It is transmitted to the shaft 12.

As shown in FIGS. 1 and 3, the boarding operation unit 7 is supported by a boarding step 21 connected to the left and right of the body frame 6 and a steering post 22 erected on the front upper part of the hydrostatic continuously variable transmission 4. Steering wheel 23, a pair of left and right brake pedals 24 disposed on the right side of the steering post 22, a transmission pedal 26 disposed on the right side of the body frame 6, and a driver seat disposed above the rear of the transmission case 5. 27 and the like.
[Running operation mechanism]

FIG. 4 is a block diagram of a traveling operation mechanism provided in the tractor.
As shown in this figure, the traveling operation mechanism includes a hydraulic transmission cylinder 42 (hereinafter, abbreviated as a transmission cylinder 42) for shifting the hydrostatic continuously variable transmission 4 and an accelerator device 30 for the engine 1. An electric actuator 31 (hereinafter referred to as an accelerator actuator 31) as an engine speed control device to be operated and a control means linked to the accelerator actuator 31 and linked to a servo control mechanism 43 that controls the shift cylinder 42. 100.

  Further, the traveling operation mechanism detects a shift pedal 26 and an accelerator lever 28 provided in the boarding operation unit 7, and an operation position of the shift pedal 26, and is a rotary type as a sensor that outputs this detection information to the control means 100. A potentiometer 36 (hereinafter referred to as a pedal sensor 36) and a rotary potentiometer 29 (hereinafter referred to as an accelerator lever) as a sensor for detecting the operation position of the accelerator lever 28 and outputting the detected information to the control means 100. (Referred to as sensor 29).

  The transmission cylinder 42 is installed inside the transmission case 5 and changes the hydrostatic continuously variable transmission 4 by changing the swash plate angle of the hydraulic pump 40. As shown in FIG. 4, the servo control mechanism 43 includes a forward proportional control valve 44 and a reverse proportional control valve 45, and the forward proportional control valve 44 and the reverse proportional control valve 45 are switched according to a command from the control means 100. Then, the shift cylinder 42 is operated so that the hydrostatic continuously variable transmission 4 enters a shift state corresponding to the operation position of the shift pedal 26. The servo control mechanism 43 is provided in the mission case 5.

  The control means 100 is configured using a microcomputer, and detects a shift state of the hydrostatic continuously variable transmission 4 based on information detected by the pedal sensor 36 and a swash plate angle. On the basis of the detected information, the variable speed cylinder 42 is operated via the servo control mechanism 43 so that the hydrostatic continuously variable transmission 4 enters a shift state corresponding to the operation position of the shift pedal 26.

Based on the detection information by the accelerator lever sensor 29 and the detection information by the accelerator sensor 32 that detects the operation state of the accelerator device 30, the control means 100 determines the rotational speed at which the accelerator device 30 corresponds to the operation position of the accelerator lever 28. The accelerator actuator 31 is operated so as to be in an operation state for causing the engine 1 to appear.
The accelerator lever 28 is configured such that its operation position is held by a well-known friction holding mechanism (not shown), the accelerator lever 28, an accelerator lever sensor 29 for detecting the position of the accelerator lever 28, and an accelerator device. The accelerator sensor 32 for detecting the operation state of 30, the control means 100, and the accelerator actuator 31 constitute a rotation speed maintaining mechanism for keeping the engine speed constant and performing work travel.

  In driving the tractor, when the speed change pedal 26 is depressed from the neutral state to the front side of the vehicle body (clockwise in the figure), the control means 100 operates the speed change cylinder 42 to the forward side and the hydrostatic continuously variable transmission 4. Is shifted forward and the tractor travels forward. When the shift pedal 26 is depressed from the neutral state toward the rear of the vehicle body (counterclockwise in the figure), the control means 100 operates the shift cylinder 42 to the reverse side and the hydrostatic continuously variable transmission 4 shifts to the reverse side. Operated, the tractor travels backward. In both forward travel and reverse travel, as the depression stroke of the shift pedal 26 is increased, the control means 100 operates the shift cylinder 42 to the higher speed side and the hydrostatic continuously variable transmission 4 shifts to the higher speed side. Operated, the tractor travel speed increases.

[Energy saving mode selection tool]
As shown in FIGS. 3 and 4, a push button switch 50 a as an energy saving mode selection operation tool 50 for inputting an energy saving mode selection signal to the control means 100 is provided on the front panel 7 </ b> A of the boarding operation unit 7. . When the control means 100 detects a signal indicating that the push button switch 50a has been pressed, the engine speed and the hydrostatic continuously variable transmission 4 are based on the speed control means 101 stored as a program in the control means 100. The vehicle speed is controlled by.

That is, as shown in FIGS. 5 and 4, when the control means 100 detects a signal indicating that the push button switch 50a has been pressed, the engine speed is reduced by a predetermined speed, and at the same time, the hydrostatic stepless With respect to the shift cylinder 42, the hydrostatic continuously variable transmission 4 is operated to the speed increasing side so as to increase the vehicle speed to the extent that the transmission 4 can compensate for the deceleration of the traveling speed due to the decrease in the engine speed. Outputs speed increase command. In this case, the predetermined rotational speed is configured to be changeable in advance and is configured so that the acceleration amount of the hydrostatic continuously variable transmission 4 can be changed to large or small in accordance with the change of the predetermined rotational speed. May be.
Based on the detection signal indicating that the push button switch 50a has been pressed, the control means 100 is currently operating in the energy saving mode on the display means such as the liquid crystal panel 70 provided on the front panel 7A. Is configured to output a signal for displaying character data or a display mark.

FIG. 6 shows another example of the control mode by the energy saving mode selection operation tool 50. Compared with the control shown in FIG. 5, in addition to increasing the traveling speed, the PTO shift is operated to the speed increasing side.
That is, as the engine speed is reduced, the output speed of the power take-off shaft 12 is also reduced in addition to the reduction in the vehicle speed, so this output speed is also equal to the speed before the engine speed is reduced. The shifter operating cylinder (not shown) is operated based on the command of the work speed control means 102 stored as a program in the control means 100 so as to restore the value to the value of PTO, and the PTO transmission 20 is switched to the speed increasing side. Control is performed to increase the operating speed of the work device.

FIG. 7 shows still another example of the control mode by the energy saving mode selection operation tool 50.
In this control mode, it is possible to perform the control for selecting the energy saving mode simultaneously with the operation of turning on the key switch, and it is possible to reduce the engine speed by the push button switch 50a a plurality of times. In addition, an engine speed detection signal is input to the control means 100 to determine whether the engine speed is within an allowable range.
That is, the engine speed reduced by the predetermined speed by the energy saving mode selection operation tool 50 is within the allowable range, that is, the working speed of the working device driven by the PTO shaft does not fall below the lower limit of the appropriate working speed range. It is determined whether or not the engine speed is within the allowable range, and the engine speed can be reduced as many times as possible. In other words, the reduction speed of the engine speed by a single reduction operation is reduced, and the speed can be changed little by little.

FIG. 8 shows still another example of the control mode by the energy saving mode selection operation tool 50.
In this control mode, control for switching the PTO transmission 20 to the speed increasing side to increase the operating speed of the working device is added to the control mode of FIG.

[Another embodiment]
[1] The position where the push button switch 50a is provided is not limited to the above-described front panel 7A, and may be any place that can be easily operated by the driver during traveling by one touch. It may be provided.

[2] The energy saving mode selection operation tool 50 is not limited to the push button switch 50a, but may be any one that can be switched by a one-touch operation, such as a switch.

[3] The work vehicle of the present invention is not limited to the one having the hydrostatic continuously variable transmission 4 shown in the above-described embodiment, but by a gear transmission or a combination of a hydraulic clutch and a constant gear. Transmission structure. Alternatively, a transmission structure using CVT or the like may be used.

[4] Instead of the shift cylinder 42 of the above embodiment, a configuration may be adopted in which the hydrostatic continuously variable transmission 4 is shifted by a drive mechanism that is a combination of a motor and a screw mechanism. Therefore, the speed change cylinder 42 and the drive mechanism are collectively referred to as a speed change actuator 42.

[5] The present invention can be applied to a work vehicle including a crawler type traveling device instead of the front wheel 8 and the rear wheel 9. Accordingly, the wheels 8 and 9 and the crawler type traveling device are collectively referred to simply as traveling devices 8 and 9.

[6] The present invention can be applied to a speed change operation device equipped in various work vehicles such as a mower, in addition to the speed change operation device provided in the tractor. Therefore, these tractors, mowers, etc. are collectively referred to as work vehicles.

Side view of the entire tractor Power transmission diagram showing the transmission structure of the tractor in FIG. Plan view showing boarding operation part Block diagram showing control means and input / output devices in the traveling operation mechanism Flow chart showing control mode in energy saving mode Flow chart showing another control mode in energy saving mode Flow chart showing another control mode in energy saving mode Flow chart showing another control mode in energy saving mode

Explanation of symbols

2 Engine 4 Hydrostatic continuously variable transmission 20 PTO transmission 28 Accelerator lever 29 Accelerator lever sensor 30 Accelerator apparatus 31 Accelerator actuator 42 Shift actuator 50 Energy saving mode selection operation tool 50a Push button switch 100 Control means 101 Speed control means 102 Working speed Control means

Claims (3)

In a work vehicle equipped with a rotation speed maintenance mechanism for keeping the engine speed constant and running the work,
An energy-saving mode selection operation tool for outputting a control signal to the engine speed control device so as to reduce the engine speed by a predetermined amount during work traveling at a set speed by the speed maintaining mechanism;
A work vehicle comprising speed control means for operating the transmission so that the rate of decrease in traveling speed is less than the rate of decrease in engine speed based on detection that the energy saving mode selection operation tool has been operated.
The engine speed reduced by the energy-saving mode selection operation tool is the speed of the energy-saving mode selection operation tool so that the work speed of the work device driven by the power take-off shaft does not fall below the lower limit of the appropriate work speed range. The work vehicle according to claim 1, wherein a reduction amount is set.
  The work vehicle according to claim 1, further comprising a work speed control unit that outputs a speed increase command to the PTO transmission based on detection that the energy saving mode selection operation tool is operated.

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