JP2009214877A - Agricultural tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agricultural tractor capable of realizing safety in high-speed travel while enabling automatic speed change without any troublesome operation in on-road driving. <P>SOLUTION: In the agricultural tractor, the rotational power from an engine is transmitted to traveling wheels via a traveling transmission mechanism composed of a main speed change device, a sub speed change device or the like, and the speed change of the main speed change device is changed by the automatic mode switch operation into the manual speed change mode for performing the speed change of the main speed change device by an acceleration/deceleration switch and the automatic speed change mode for performing the speed change of the main speed change device by an accelerator pedal. A means is provided, which couples or uncouples right and left brakes. When the vehicle speed exceeds the predetermined value, and the right and left brakes are not coupled with each other, the display for promoting the coupling of the right and left brakes is made on a liquid crystal display unit 84. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an agricultural tractor.

  Agricultural tractors are equipped with manual shifting by operating the increase / decrease switch and automatic transmission control that switches and controls the transmission gear ratio of the main transmission of the traveling transmission device according to the engine speed in the traveling on the road. There is a configuration capable of automatic shifting (Patent Document 1).

  In addition, there is a configuration in which a liquid crystal display unit is provided on the instrument panel to display vehicle speed, PTO rotation speed, and the like (Patent Document 2).

JP 2003-278903 A JP-A-5-338467

  By the way, since it is not necessary to perform multi-stage gear shifting while traveling on the road, some of them are targeted for gear shifting. However, the number of gears has to be changed depending on the skill level of the operator. According to the present invention, the number of setting stages can be arbitrarily set in advance, and an attempt is made to eliminate the above-described drawbacks.

  In addition, the liquid crystal display unit displays a message when it is not suitable for automatic shift control in road driving, and prompts the operator to change the setting.

  For this reason, the invention according to claim 1 employs the following configuration. That is, the rotational power from the engine (5) is transmitted to the traveling wheels (3, 3) via the traveling transmission mechanism including the main transmission (10, 11), the auxiliary transmission (12), etc. An automatic mode switch between a manual transmission mode in which the gears of the devices (10, 11) are shifted by the speed increase / decrease switch (37, 38) and an automatic transmission mode in which the gears of the main transmission (10, 11) are shifted by the accelerator pedal (58). (55) In the agricultural tractor configured to be switched by operation, means for connecting or releasing the left and right brakes is provided, and when the vehicle speed exceeds a predetermined speed and the left and right brakes are not connected, the liquid crystal display unit (84) A display for prompting the left and right brake connection is performed.

  According to a second aspect of the present invention, in the first aspect, the speed change range by the accelerator pedal (58) can be set to a smaller number of steps with respect to the speed change range by the acceleration / deceleration switch (37, 38), and the speed change number can be changed and set. Provided, when there is a shift operation by the acceleration / deceleration switch (37, 38) during the automatic shift mode by the accelerator pedal (58), the shift control is performed by giving priority to the operation of the acceleration / deceleration switch (37, 38). .

  According to the first aspect of the present invention, the automatic mode switch (55) can be selected between the speed change operation by the acceleration / deceleration switch (37, 38) and the automatic speed change operation by the accelerator pedal, and when the automatic mode switch (55) is operated. The main transmission (10, 11) using the accelerator pedal (58) can be shifted, and the main transmission (10, 11) can be sequentially switched by a predetermined number of steps.

  In the automatic transmission mode, when the vehicle speed exceeds a predetermined speed or more and the left and right brakes are not connected, the danger caused by high speed running is prevented by displaying on the liquid crystal display part the prompting for the left and right brake connections.

  According to the invention described in claim 2, in addition to the effect described in claim 1, the predetermined number of steps of the main transmission (10, 11) set in advance can be changed and set to the number of gears according to the skill level of the operator. It can be set, and even during automatic shifting by the accelerator pedal (58), the manual operation using the acceleration / deceleration switch (37, 38) is prioritized, so that the target vehicle speed can be obtained quickly.

It is the whole tractor side view. It is a power transmission diagram. It is a perspective view of a transmission lever part. It is a table | surface which shows the relationship between each transmission and a gear stage number. It is a block diagram. It is a front view of an instrument panel part. It is a front view of a liquid crystal display screen. It is a figure explaining a mode when a liquid crystal display screen switches in order. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a sample figure of a liquid crystal display. It is a flowchart of transmission control. It is a flowchart of transmission control.

Embodiments will be described below with reference to the drawings.
FIG. 1 is a side view of the tractor 1. The tractor 1 has front wheels 2 and 2 for steering and large-diameter rear wheels 3 and 3, and the rotational power of the engine 5 mounted in the bonnet 4 is appropriately decelerated by a transmission in the transmission case 6 and rotated. Power is transmitted to the front wheels 2, 2 and the rear wheels 3, 3.

  Further, in the transmission case 6, a forward / reverse switching device 9 for switching the advancing direction of the airframe, a main transmission device 10 capable of shifting in eight steps, and an auxiliary transmission device 12 capable of shifting in three steps are connected in series. ing. These transmission systems will be described later with reference to FIG.

  In FIG. 1, a hydraulic cylinder case 14 is provided at an upper portion of the transmission case 6, and lift arms 15, 15 are pivotally attached to left and right sides of the hydraulic cylinder case 14. Lift rods 17, 17 are connected between the lift arms 15, 15 lower links 16, 16, and a rotary tiller 18, which is a work machine, is connected to the lower part of the lower link 16, 16. When the hydraulic oil is supplied to the hydraulic cylinder 14a accommodated in the hydraulic cylinder case 14 by operating the hydraulic operation lever 28 to the upward side, the lift arms 15 and 15 are rotated upward, and the lift rod 17 and the lower link 16 are rotated. Etc., the work machine rises. On the contrary, when the hydraulic control lever 28 is operated to the lower side, the hydraulic oil in the hydraulic cylinder 14a is discharged into the transmission case 6 which also serves as a hydraulic tank, and the lift arms 15 and 15 are lowered.

  Reference numeral 18 denotes a rotary tiller. The rotary tiller 18 includes a tiller 19, a main cover 20 that covers the top of the tiller 19, a rear cover 22 that is pivotally attached to the rear of the main cover 20, and the like.

  1 will be described. A forward / reverse switching lever 27 for operating the forward / reverse switching device 9 is provided at the upper part of the left and right sides of the handle post 25 that supports the steering handle 24. When the 27 is tilted forward from the neutral position, the aircraft advances, and conversely, when the aircraft is pulled rearward, the aircraft moves backward. The configuration of the instrument panel 80 will be described later.

  Next, the power transmission system will be described based on the power transmission diagram shown in FIG. A main clutch 30 is provided at the rear portion of the engine 5, and the forward / reverse switching device 9 described above is provided at the rear of the transmission of the main clutch 30. The forward / reverse switching device 9 comprises multi-plate friction type hydraulic clutches 9a, 9b, which are normally maintained in a neutral position, and the forward hydraulic clutch 9a is connected by operating the forward / reverse switching lever 27 back and forth, or The reverse hydraulic clutch 9b is connected. A synchromesh-type first main transmission 10 capable of four-speed shifting is provided at the rear of the transmission of the forward / reverse switching device 9. When the actuators 31, 31 expand and contract in response to a command from the controller 60, the shifters 32, 32 Is shifted in the front-rear direction to change speed. In FIG. 2, when the front shifter 32 moves in the front-rear direction, the fourth speed and the third speed are obtained, and when the rear shifter 32 moves in the front-rear direction, the second speed and the first speed are obtained. In this case, when the first main transmission 10 is switched, the hydraulic forward / reverse switching device 9 is first returned to the neutral state, and after the main transmission 10 is shifted, the forward / backward switching device 9 is connected again. It is configured to be.

  A hydraulic second main transmission 11 that can be switched between high and low two stages is provided at the rear of the first main transmission 10. The front hydraulic clutch 11a is a high speed clutch, and the rear hydraulic clutch 11b is a low speed hydraulic clutch. Accordingly, in the main transmissions 10 and 11 in this embodiment, a total of eight speeds can be achieved by combining the first main transmission 10 with the four speeds and the second main transmission 11 with the second speed.

  Further, the rear portion of the second main transmission 11 is provided with a sub-transmission 12 that is capable of three speeds and has a relatively large reduction ratio as compared with the main transmissions 10 and 11. When a single shift lever 34 is operated to move the front shifter 35 in the front-rear direction, high speed (H speed) and medium speed (M speed) are obtained, and the rear shifter 35 is moved rearward. If it is made, low speed (L) will be obtained. When the auxiliary transmission 12 is operated, the main clutch 30 needs to be turned on and off. That is, the main clutch pedal 29 is depressed to operate the operation lever 34 in the front-rear direction or the left-right direction, and after the shift operation, the main clutch pedal 29 is released to transmit power.

  On the other hand, with respect to the main transmissions 10 and 11, the speed change switch 37 and the speed reduction switch 38 provided on the knob of the operation lever 34 are pushed in to change the speed (see FIG. 3). In the tractor in this embodiment, the speed is changed only by one step regardless of whether the speed increasing switch 37 or the speed reducing switch 38 is pressed. By depressing the speed increasing switch 37 in order from the first speed, the speed is changed step by step up to the eighth speed. Conversely, by depressing the deceleration switch 38 in order with respect to the main transmissions 10 and 11 located at the eighth speed position, the speed can be reduced from the eighth speed to the first speed. The rotational power decelerated by the main transmissions 10 and 11 is further transmitted to the sub-transmission device 12, where it is further shifted to three speeds, and the power decelerated by the sub-transmission device 12 is transmitted to the drive pinion 40, and the rear wheels. The rear wheels 3 and 3 are driven through the differential device 41 and the final reduction device 42 in order.

  On the other hand, the power branched from the rear wheel drive system in front of the rear wheel differential device 41 is used as a front wheel drive system. In the front wheel drive system, the front wheels 2 and 2 are driven at the same speed as the rear wheels 3 and 3. A front wheel speed increasing device 44 that rotates at a higher speed than the rear wheels 3 and 3 is provided. When the front hydraulic clutch 44a is connected, the front wheel is accelerated, when the rear hydraulic clutch 44b is connected, the constant speed four-wheel drive state is established, and when both the hydraulic clutches 44a, 44b are turned off, the rear wheel 3 , 3 is a two-wheel drive state. Reference numeral 46 is a front wheel differential device, and 47 is a front wheel final reduction device.

  In the power transmission diagram of FIG. 2, only when the auxiliary transmission 12 is at a high speed (H speed), if the operation lever 34 is tilted sideways as it is, an ultra high speed (HH speed) suitable for the road traveling speed is obtained. ). In this case, the main transmissions 10 and 11 can select the 5th speed, 6th speed, 7th speed, and 8th speed on the high speed side from the 1st speed to the 8th speed, but the 4th speed on the low speed side from the 1st speed to the 4th speed is No matter how the acceleration / deceleration switches 37 and 38 are operated, the program cannot be selected. This is because when traveling on the road, high speed traveling is premised, so only the high speed side of the main transmissions 10 and 11 is prioritized, and the low speed side is cut in the program to improve operability.

  In this embodiment, the selectable number of high-speed gears is four, ie, 5, 6, 7, and 8. However, it is possible to set 6, 7, and 8 to 3 or 7 Alternatively, the number of shift stages may be reduced by a program such that only the second stage of the eighth speed.

  In the power transmission diagram of FIG. 2, a PTO system power transmission path is provided separately from the traveling system, and a PTO clutch 70 and a PTO transmission 72 that can be rotated forward and backward are interposed in the middle of the transmission path. Rotational power is transmitted to the PTO shaft 71 provided in FIG.

  FIG. 3 shows the positional relationship between the operation lever 34, the cockpit 48 and the lever guide 49. The lever guide 49 is provided on the left side of the cockpit 48, and its shape is h-shaped when viewed from above, and the operation lever 34 moves in the groove of the lever guide 49 to change speed. As is clear from the figure, a medium speed position (M speed) is provided on the opposite side of the high speed position (H speed), and a low speed position (L speed) is provided in the groove on the opposite side through the neutral position N. . By switching the shift lever 34 at the high speed position (H speed) to the side, it is switched to the super high speed position (HH speed). As described above, the high-speed position (H speed) and the super-high speed position (HH speed) change only the shift range of the main transmissions 10 and 11 without changing the shift position of the auxiliary transmission 12.

  The lever guide 49 is provided with four switches 50, 51, 52, 53 in order to detect which shift position the operation lever 34 for operating the auxiliary transmission 12 is in. Instead of these four switches 50, 51, 52, 53, the shift position of the auxiliary transmission 12 may be detected by an analog potentiometer.

  In addition to the acceleration / deceleration switches 37 and 38, the operation lever 34 is provided with an automatic mode switch 55. When the automatic mode switch 55 is depressed, a later-described accelerator pedal 58 can be shifted. More specifically, the main transmissions 10 and 11 using the accelerator pedal 58 are used only when the automatic mode switch 55 is in the ON state and the auxiliary transmission 12 is shifted to the super high speed position (HH speed). Can be changed. That is, the main transmissions 10 and 11 can be automatically increased or decreased in the range from the first speed to the eighth speed, but in this embodiment, when shifting by the accelerator pedal 58 is performed, from the fifth speed on the high speed side. It is designed to switch sequentially only in the range up to the 8th speed. Further, in this embodiment, not only automatic shift by the accelerator pedal 58 but also when the shift lever 34 is operated to switch the auxiliary transmission 12, jump to the main shift position used for a long time in the previous field and shift position. A memory shift function is provided to switch between. More specifically, the memory shift means that the auxiliary transmission 12 is switched if the auxiliary transmission 12 is in a position other than the super high speed position (HH speed) and the automatic mode switch 55 is ON. The main shift positions 10 and 11 that have been used for the longest time are automatically switched.

  For example, the auxiliary transmission 12 is in the middle speed position (M speed) and the main transmissions 10 and 11 are in the sixth speed position. In this state, work is performed for 3 hours, and then the auxiliary transmission 12 is moved to the high speed position (H Speed), when the main transmissions 10 and 11 are used at the 3rd speed for 30 minutes and the auxiliary transmission 12 is set to the medium speed position (M speed) again, the main transmissions 10 and 11 change from the current 3rd speed position to the original 6th speed. It can be automatically switched to a position. As described above, when the sub-transmission device 12 is switched in the field, the shifter 32 is moved to the switching position of the main transmissions 10 and 11 that have been used most often, in other words, the accumulated work time is long. The work efficiency is increased so that there is no hindrance to the operation.

  As described above, this memory shift is switched to the state in which the automatic mode switch 55 is turned on, and the auxiliary transmission 12 is operated at a high speed on the road (HH speed), that is, the high speed position (H speed). , It works only when it is switched to the medium speed position (M speed) and the low speed position (L speed). Therefore, when the automatic mode switch 55 is pressed, either automatic shift by the accelerator pedal 58 or memory shift is controlled.

  Next, the block diagram of FIG. 4 will be described. On the input side of the control means (controller) 60 composed of a microcomputer, main transmission position sensors 62 and 63 for reading the shift positions of the first main transmission 10 and the second main transmission 11 and a sub-position for reading the shift position of the sub-shift position 12. Shift position detection switches 50, 51, 52 and 53 are connected. Further, a forward / reverse position sensor 65 for detecting whether the forward / reverse switching lever 27 is switched to the forward side or the reverse side, and an analog type accelerator pedal sensor 66 for detecting the depression amount of the accelerator pedal 58. An engine rotation sensor 67 that detects the number of revolutions of the engine 5 and an accelerator lever sensor 68 of an accelerator lever 59 that is provided on the side of the steering handle 24 and sets a throttle operation amount during work are connected. Further, a key switch 81 and an automatic mode switch 55 are connected.

  On the other hand, a main transmission switching valve 76, a forward / reverse switching valve 77, a clutch booster valve 78, and an auto-on lamp 79 are connected to the output side of the controller 60. When the automatic mode switch 55 is pressed, the auto-on lamp 79 is turned on. In addition, a warning lamp 86 and a monitor lamp group 83, which will be described later, are connected as lamps.

  The main shift switching valve 76 is provided for switching the two actuators 31, 31 of the first main transmission 10, and the forward / reverse switching valve 77 is a valve for switching the forward / reverse switching device 9. is there.

  The clutch booster valve 78 is interposed in order to gradually increase the pressure of the hydraulic clutch that constitutes the forward / reverse switching device 9 when switching the main transmission 10 and to smoothly connect the clutch.

  Next, the configuration of the instrument panel 80 shown in FIG. 6 will be described. The instrument panel 80 is provided with an engine tachometer 82 at the center, a plurality of monitor lamp groups 83 are provided on the left side thereof, and a rectangular liquid crystal display unit 84 is provided on the right side of the engine tachometer 82. ing.

  The monitor lamp group 83 includes a front wheel acceleration mode in which the front wheel 2 is accelerated in conjunction with the turning operation, an autolift mode in which the work machine is automatically raised in conjunction with the turning operation, and a turning inside in conjunction with the turning operation. It is turned on in accordance with various control modes selected during the work, such as an auto brake mode in which the brake device operates.

  Reference numeral 85 is a blinker lamp, and 86 is a warning light. The liquid crystal display unit 84 in FIG. 7 will be further described. The shift position of the sub-transmission device 12 is displayed on the upper left of the liquid crystal display unit 84, and the shift positions of the main transmissions 10 and 11 are displayed in reverse on the right side. In the lower part, the vehicle speed, the remaining amount of fuel, and the water temperature are displayed. In this embodiment, the auxiliary transmission 12 is switched to the low speed state (L), the main transmission is in the seventh speed, and the vehicle speed is 1.2 km / h.

  The display content in the lower part of the liquid crystal display unit 84 changes every time the display changeover switch 87 is pressed, and the vehicle speed is displayed on the first screen, but when the display changeover switch 87 is pressed once, the number of rotations of the PTO. Is displayed, the next time the switch 87 is pressed, the hour meter display in which the engine is running is accumulated. When this switch 87 is pressed again, the trip meter is displayed. When the switch 87 is pressed again, the type of control mode (for example, auto mode, load) is displayed. (Auto mode, horizontal mode, etc.) are displayed (see FIG. 8). The contents displayed in the lower part of the liquid crystal display unit 84 are stored in a non-volatile storage device (EEPROM) when the engine is stopped. Therefore, when the engine is restarted, the display contents that were used until immediately before the engine stop operation are reproduced as they are, and there is no need for the operator to call in order from the initial setting screen, so the original setting screen is restored each time. The operability is greatly improved without the time and effort required. The display changeover switch 87 may be provided at any location facing the driver's seat. In this embodiment, the display changeover switch 87 is provided on the left side of the handle post 25. The display changeover switch 87 is also connected to the controller 60, and the display content of the liquid crystal display unit 84 is changed in response to an instruction from the controller 60.

  In this embodiment, when an abnormal state occurs during operation, the liquid crystal display unit 84 displays the details of the abnormality. For example, if the water temperature is abnormal, “water temperature abnormality, idling” is displayed. If the engine oil is insufficient and abnormal, the message "Engine oil abnormal, please check" is displayed. If the alternator malfunctions, "Charging error, check" Please "message is displayed. The contents of these abnormalities are displayed as an interrupt screen with respect to the normal screen that has been displayed so far. When the display changeover switch 87 is switched, the screen returns from the interrupt screen to the normal display screen. Since it is not avoided, in such a case, the warning lamp 86 is blinked at the same time while displaying a normal display screen. Repeats blinking unless an evasive action is taken for an abnormal condition.

  Further, FIG. 9 shows that the position of the auxiliary transmission operating lever 34 is changed in the horizontal and lateral directions when the auxiliary transmission 12 is at the high speed position (H speed) and when it is at the ultra high speed position (HH speed) on the road. Sometimes, a part of the display part of the liquid crystal display part 84 is blinked to indicate that the operation lever 34 has been moved by mistake. As described above, the sub-transmission operation lever 34 does not change the shift position of the sub-transmission, but simply selects the fifth, sixth, seventh, and eighth speeds on the high speed side of the main transmission, or the first to eighth speeds. Since the operator's knee accidentally touches the speed change lever 34 and the operation part of the speed change lever 34 falls in the horizontal direction, the high speed position (H speed) There is a case where the switch 50 is switched to the ultra high speed position (HH speed) and the ultra high speed switch 50 is turned on. In this way, when only the speed change lever 34 is switched in an unexpected state, a part of the display items of the liquid crystal display section 84, in this embodiment, the main speed change position (six speed) and the sub speed change position (high speed). Are simultaneously blinked to notify the operator that the operating lever 34 has been erroneously switched from the high speed position (H speed) to the super high speed position (HH speed).

  In addition, the items other than those described above in the display contents on the liquid crystal display unit 84 will be described. The lift arms 15 and 15 are in the raised position, the hydraulic operation lever 28 is in the lowered position, and the speed change operation lever 34 is traveling on the road. When the super-high speed position (HH speed) or the actual vehicle speed is 7 km / h or higher, a message “Please raise the hydraulic control lever” is sent to alert the operator.

  FIG. 11 illustrates the display contents when the stored main shift position is changed during the memory shift control. Since the memory shift is described above, a detailed description is omitted. However, when the position stored in the storage device (EEPROM) at the main shift position used during the work is changed, the changed shift position is set. Displayed on the liquid crystal display unit 84. The example described in FIG. 11 indicates that when the sub-shift position is at a low speed, the main shift position stored as the memory shift is changed to the sixth speed. However, the change display in this case is only when the automatic mode switch 55 is ON.

  FIG. 12 shows the contents of a message displayed when the engine speed is high when the speed change lever 34 is in the super high speed position (HH speed) as traveling on the road. That is, since automatic shifting using the accelerator pedal 58 is mainly performed on the road regardless of the accelerator lever 59, when the engine idling speed is high, for example, when the idling speed exceeds 1000 rpm, the "accelerator The message “Please return the lever and drive with the accelerator pedal” is displayed on the liquid crystal display unit 84.

  FIG. 13 shows a display when the water temperature is abnormally high. If the detected water temperature of the engine cooling water exceeds 100 ° C when the engine is started, and the engine continues to run for more than 10 seconds, the engine may overheat. Is displayed on the liquid crystal display unit 84.

  FIG. 14 explains the parking cancellation display. In other words, when the parking brake that keeps the parking state is operating, if the aircraft is driven, the brake will generate heat and cause a failure. Please display ". Specifically, the above message is displayed when the oil pressure switch is OFF and the parking switch is ON and the vehicle speed is 0.5 km / h or more.

  FIG. 15 explains the message for prompting the brake connection. That is, when the vehicle speed exceeds 10 km / h and the left and right brake pedals are not connected, the message “Please connect the brake pedal” is sent to the liquid crystal display unit 84. Since it is very dangerous to drive at high speed without connecting the brake pedal, in such a case, it is effective to make not only a liquid crystal display but also an alarm sound by a buzzer or the like.

  FIG. 16 shows whether or not the mode is suitable for driving on the road when the travel mode selection switch 89 for selecting the travel mode is selected and the travel mode is selected, and that is displayed when it is not suitable. It is. The work switching dial 89 has a 2WD mode suitable for running on the road, a 4WD mode for simultaneously driving the front and rear wheels, a front wheel double speed mode for accelerating the front wheel relative to the rear wheel during turning, a front wheel double speed state during turning, and The brake turn mode for braking the brake on the inside of the turn can be switched, and when the operation lever 34 for switching the auxiliary transmission 12 is at the road speed, the brake turn for turning by operating the front wheel double speed or the brake device on the inside of the turn is made. In order to prohibit it, the message “Please switch the work switching dial to 2WD or 4WD” is displayed.

Finally, a method of setting the tractor class will be described with reference to FIGS.
For example, various types of tractors are set depending on differences in horsepower and the like, and when the tractors are shipped from a factory, the types need to be set. This is because, in particular, when displaying the vehicle speed, it is necessary to refer to a constant determined for each model and use it for vehicle speed calculation.

  The setting for this is the class setting mode. Although illustration is omitted to enter this class setting mode, the check mode is first entered by operating the check switch. Then, the display changeover switch 87 is operated to shift to the class setting screen, and the display changeover switch 87 is further pressed to select the target tractor class (horsepower or specification). In FIG. 17, for example, when 23 horsepower FF is selected, the display changeover switch 87 is continuously pressed for 2 seconds or more to confirm it. Then, the screen shifts to a class setting OK / NG selection screen (FIG. 18) for confirming whether or not class setting may be performed. The selection of OK or NG is also performed by the display changeover switch 87. The black and white inversion portion is confirmed on the screen on the selected side, and in either case, the class setting is determined by pressing the display changeover switch 87 for 2 seconds or more. Instead of this method, the class may be set by a separate confirmation switch. However, in this embodiment, the display changeover switch 87 is also used as a confirmation switch as it is to reduce the number of switches. . In addition, regarding the setting of this type, when data related to the type has already been written in the storage device (EEPROM) of the controller and the data to be set this time matches the written data, the storage device is not rewritten. . If they are different, data relating to the newly set type is written. Class setting such as the type must be carefully performed. For this reason, in this embodiment, after the class is selected, a confirmation screen is displayed once, and OK or NG is selected so that the class is definitely set correctly.

Next, the operation of the shift control will be described.
19 and 20 are flowcharts illustrating a control program for shift control. A program having the contents shown in FIGS. 19 and 20 is incorporated in the memory of the controller 60.

FIG. 19 will be described. First, the state of sensors and switches is read (step S1), and it is further determined whether or not the automatic mode switch 55 is ON (step S2). That is, it is determined whether or not the super high speed position (HH speed) is reached (step S3). When the super high speed position (HH speed) set as the road traveling speed is selected, the PTO transmission is in the neutral position (step S5), and the accelerator lever 59 is in the high rotation position (step S5). S6) When the hydraulic control lever 28 is operated to be raised (step S7), the auto-on lamp 79 is turned on (step S8), and the shift by the accelerator pedal 58 is enabled only when the aircraft is moving forward. (Steps S9 and S10).

  The automatic shift by the accelerator pedal 58 is determined by the engine speed and the depression position of the accelerator pedal 58, and these relationships are stored in a storage device (ROM) in the controller 60 as a data map.

  As the amount of depression of the accelerator pedal 58 increases and at the same time the number of revolutions of the engine 5 increases, the main transmissions 10 and 11 are switched to the speed increasing side. In this case, the main transmissions 10 and 11 are decelerated and decelerated within the range from the fifth speed to the eighth speed on the high speed side.

  In the above example, when the auxiliary transmission 12 is at a speed other than the road speed, in other words, when the auxiliary transmission 12 is at the high speed position (H speed), the medium speed position (M speed), and the low speed position (L speed), the accelerator Only the speed change by the acceleration / deceleration switches 37 and 38 is possible without the speed change by the pedal 58 (step S12).

  Even if the auxiliary transmission 12 is shifted to the super high speed position (HH speed), the PTO transmission is not in the neutral position, the accelerator lever 59 is not set to the high rotation position, or the hydraulic control lever 28 is If it is not operated to the ascending side, the current main shift position is maintained as it is without permitting automatic shift by the accelerator pedal 58 (step S11).

  Immediately after the sub-transmission device 12 is shifted to the super high speed position (HH speed), it is shifted to the first speed position set as the road speed. In this embodiment, the fifth speed position is the first speed on the road speed. A small tractor with a low vehicle speed may be configured to start from the second speed on the road, that is, the sixth speed of the main speed change.

  Next, the flowchart of FIG. 20 will be described. This control flowchart gives priority to the operation by the acceleration / deceleration switches 37 and 38 provided on the operation lever even when the automatic shifting by the accelerator pedal 58 is performed, or the main transmission is operated by the operation of the acceleration / deceleration switches 37 and 38. This is characterized in that the shift by the accelerator pedal 58 is continued even after the operation.

  Explaining for each step, when a deceleration command is output from the controller based on the relationship between the accelerator opening and the engine rotation, the main shift is decelerated by one step (steps SS1, SS2), and conversely, an increase is instructed. If it is, the main speed is increased by one step (step SS3).

  At this time, it is determined whether or not the speed increase / decrease switches 37 and 38 of the main transmission have been operated. When the speed change switch 38 is operated (step SS4), the shift position indicated by the accelerator pedal 58 is determined. If a comparison is made and there is a need for further deceleration, a shift is performed to the indicated position of the deceleration switch 38 (step SS5). In this case, after that, accelerator pedal shift is prohibited for a predetermined time in order to stabilize the control (step SS7). Further, when the main gear speed increase switch 37 is pressed during the automatic speed change by the accelerator pedal 58 and a speed increase is instructed, the indicated position is compared with the speed change position instructed by the accelerator pedal 58 to increase the speed. When the shift instruction position by the switch 37 is larger than the instruction position by the accelerator pedal 58, the speed is preferentially increased.

  As described above, since the manual operation using the acceleration / deceleration switches 37 and 38 is prioritized even during the automatic shift by the accelerator pedal 58, the target vehicle speed can be obtained quickly and as the operator intends. The tractor can be driven.

1 Tractor
2 Front wheels
3 Rear wheels
4 Bonnet
5 Engine
6 Mission case
9 Forward / reverse switching device
10 First main transmission
11 Second main transmission
12 Sub-transmission
34 Shifting control lever
37 Speed up switch
38 Deceleration switch
55 Automatic mode switch 58 Accelerator pedal 84 Liquid crystal display

Claims (2)

  The rotational power from the engine (5) is transmitted to the traveling wheels (3, 3) through the traveling transmission mechanism including the main transmission (10, 11), the auxiliary transmission (12), etc., and the main transmission ( The automatic mode switch (55 ) In the agricultural tractor configured to switch by operation, means for connecting or releasing the left and right brakes is provided, and when the vehicle speed exceeds a predetermined speed and the left and right brakes are not connected, the left and right brakes are connected to the liquid crystal display unit (84). Agricultural tractor with a structure that prompts the user to connect the brake.   An automatic shift mode using the accelerator pedal (58) is provided such that the shift range by the accelerator pedal (58) is set to a smaller number of steps than the shift range by the acceleration / deceleration switch (37, 38), and the number of shift steps can be changed. The agricultural tractor according to claim 1, wherein when there is a speed change operation by means of an acceleration / deceleration switch (37, 38), the speed increase / decrease switch (37, 38) operation is prioritized for speed change control.

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