JP2005226728A - Travel transmission structure for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel transmission structure for a working vehicle, wherein travel transmission devices are constituted to be operated to a low speed side or to a high speed side depending on a load on an engine, allowing adequate setting of the travelling speed of a vehicle body in responce to working conditions. <P>SOLUTION: The travel transmission structure comprises travel transmission devices 10, 11 and a shift means for operating the travel transmission devices 10, 11. An automatic shift means uses the shift means for operating the travel transmission devices 10, 11 from a reference shift position to the low speed side or the high speed side depending on the load on the engine 1. The reference shift position is changeable in an artificial manner. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a traveling speed change structure for a work vehicle.

In some work vehicles, for example, as disclosed in Patent Document 1, there is a work vehicle configured to automatically operate a traveling transmission device on a high speed side and a low speed side in accordance with a load applied to an engine.
In Patent Document 1, the actual engine speed is detected and determined as a load applied to the engine. When the actual engine speed decreases, the traveling transmission is operated to the low speed side, and the actual engine speed is reduced. When the engine speed increases, the traveling transmission is configured to be operated to the high speed side. Thus, the actual transmission speed is maintained within the set range (the load applied to the engine is maintained within the set range) by operating the traveling transmission device to the low speed side and the high speed side.

Japanese Patent Laid-Open No. 2002-106697 (FIGS. 1, 2, 4, and 6)

In a work vehicle, it is necessary to change and set the traveling speed of the airframe to an appropriate one according to various work conditions (the type of work device connected to the airframe, the state of the work ground, and the like).
In the traveling speed change structure of the work vehicle, when the traveling transmission is configured to be operated to the low speed side and the high speed side according to the load applied to the engine, the traveling speed of the airframe is appropriately set according to the working conditions. It is intended to be configured so that it can be set to.

[I]
(Constitution)
A first feature of the present invention resides in the following structure in a traveling speed change structure for a work vehicle.
A transmission for traveling and a transmission mechanism for operating the transmission for traveling are provided. An automatic transmission means is provided for operating the traveling transmission device from the reference shift position to the low speed side and the high speed side by a speed change mechanism in accordance with a load applied to the engine. The reference shift position can be artificially changed.

(Function)
According to the first aspect of the present invention, the reference shift position is artificially changed in a state where the traveling transmission is operated from the reference shift position to the low speed side and the high speed side by the speed change mechanism according to the load applied to the engine. can do.
Thus, according to the first feature of the present invention, for example, when the driver artificially changes the reference shift position to the low speed side, the traveling transmission device is operated from the low speed side reference shift position to the low speed side and the high speed side. Therefore, for example, when the driver artificially changes the reference shift position to the high speed side, the driving shift from the reference shift position on the high speed side is performed. The device is operated to the low speed side and the high speed side (the state where the shift range of the traveling transmission is changed to the high speed side).

  As described above, according to the first feature of the present invention, in the state in which the traveling transmission is operated from the reference shift position to the low speed side and the high speed side by the speed change means according to the load applied to the engine, Accordingly, by manually changing the reference shift position accordingly, the shift range of the transmission for traveling can be set to be suitable for the work conditions.

(The invention's effect)
According to the first feature of the present invention, in the traveling speed change structure of the work vehicle, when the traveling speed change device is operated to the low speed side and the high speed side by the speed change mechanism in accordance with the load applied to the engine, The transmission range of the transmission can be set to a value suitable for the working conditions, and the traveling speed change performance of the work vehicle can be improved.

[II]
(Constitution)
The second feature of the present invention resides in the following structure in the traveling speed change structure for a work vehicle according to the first feature of the present invention.
A manual operation tool that is artificially operated, and a manual transmission unit that operates a traveling transmission device with a transmission mechanism based on the operation of the human operation tool. Selection means is provided that can artificially select a manual mode in which the manual transmission means operates and a load mode in which the automatic transmission means operates. The reference transmission position can be changed by the manual transmission means.

(Function)
According to the second feature of the present invention, the “action” described in the preceding item [I] is provided in the same manner as the first feature of the present invention, and in addition to this, the following “action” is provided.
According to the second aspect of the present invention, when the load mode is selected by the selection means, the traveling transmission device is moved from the reference shift position by the speed change mechanism according to the load applied to the engine as described in [I] above. A state (automatic transmission means, load mode) operated on the side and the high speed side is obtained. When the manual mode is selected by the selection means, the traveling transmission device is operated based on the operation of the manual operation tool (manual transmission means, manual mode), so that the driver operates the manual operation tool. The traveling transmission can be operated to a desired shift position.

  In this case, according to the second feature of the present invention, the reference speed change position can be changed by the manual speed change means, so that the driver operates the manipulator to set the traveling speed change device to the desired speed change position. The reference shift position can be changed as if it were operated (as described in [I] above, the shift range of the traveling transmission can be changed to the low speed side and the high speed side).

(The invention's effect)
According to the second feature of the present invention, the “effect of the invention” described in the preceding item [I] is provided in the same manner as the first feature of the present invention. In addition, the following “effect of the invention” is provided. ing.
According to the second feature of the present invention, in addition to the state (automatic transmission means, load mode) in which the transmission for traveling is operated to the low speed side and the high speed side by the speed change mechanism in accordance with the load applied to the engine, Based on this operation, a state (manual transmission means, manual mode) in which the traveling transmission is operated can be obtained, and the traveling shift functionality of the work vehicle can be improved.
According to the second feature of the present invention, the driver can change the reference shift position as if he / she operated the travel transmission to a desired shift position by operating the manipulator. As a result, the operation feeling of the traveling shift of the work vehicle can be improved.

[III]
(Constitution)
A third feature of the present invention resides in the following configuration in the traveling speed change structure for a work vehicle according to the first or second feature of the present invention.
The automatic transmission means is configured so that the travel transmission is operated from the reference shift position to the low speed side within a predetermined range, and the travel transmission is operated from the reference shift position to the high speed side within the predetermined range.

(Function)
According to the third feature of the present invention, the “action” described in the preceding item [I] [II] is provided in the same manner as the first or second feature of the present invention. In addition, the following “action” is provided. It has.
According to the third aspect of the present invention, in the state where the traveling transmission is operated from the reference shift position to the low speed side and the high speed side by the speed change means according to the load applied to the engine, the shift range of the traveling transmission apparatus is Therefore, the traveling transmission is not operated on the low speed side beyond the predetermined range, and is not operated on the high speed side beyond the predetermined range.

  Thus, according to the third aspect of the present invention, in the state where the travel transmission is operated from the reference shift position to the low speed side and the high speed side by the speed change means according to the load applied to the engine, the travel transmission is Since the speed change range of the traveling transmission device is limited to a predetermined range (relatively narrow) without being operated more than necessary to the low speed side and the high speed side, it does not deviate much from the working conditions. The shift range of the traveling transmission can be set to be suitable for the working conditions.

(The invention's effect)
According to the third feature of the present invention, the “effect of the invention” described in the preceding paragraphs [I] and [II] is provided in the same manner as the first or second feature of the present invention. The effect of the invention is provided.
According to the third feature of the present invention, the shift range of the transmission for traveling can be set to be suitable for the work condition without deviating from the work condition so much, and the traveling shift performance of the work vehicle can be improved. I was able to improve.

[1]
FIG. 1 shows a transmission case 8 of a four-wheel drive agricultural tractor that is an example of a work vehicle. The power of the engine 1 is a forward clutch 5 or a reverse clutch 6, a cylindrical shaft 7, a first main transmission 10 (traveling). For transmission), the second main transmission 11 (corresponding to the transmission for traveling), the auxiliary transmission 12 and the rear wheel differential device 13 to be transmitted to the rear wheel 14. The power branched from immediately before the rear wheel differential device 13 is transmitted to the front wheel 19 through the transmission shaft 15, the hydraulic clutch type front wheel transmission device 16, the front wheel transmission shaft 17 and the front wheel differential device 18. The power of the engine 1 is transmitted to the PTO shaft 4 through the transmission shaft 2, the hydraulic multi-plate PTO clutch 3 and the PTO transmission 9.

  As shown in FIG. 1, the forward and reverse clutches 5 and 6 are hydraulic multi-plate types in which a friction plate (not shown) and a piston (not shown) are combined, and are operated to the transmission side by supplying hydraulic oil. Is done. When the forward clutch 5 is operated to the transmission side, the power of the engine 1 flows directly from the forward clutch 5 to the cylindrical shaft 7 to advance the machine body. When the reverse clutch 6 is operated to the transmission side, the power of the engine 1 is transmitted to the cylindrical shaft 7 in the reverse rotation state via the reverse clutch 6 and the transmission shaft 20 and the airframe moves backward.

  As shown in FIG. 1, the first main transmission 10 is a hydraulic clutch type in which four hydraulic multi-plate type first speed clutch 21, second speed clutch 22, third speed clutch 23 and fourth speed clutch 24 are arranged in parallel. The speed of the cylindrical shaft 7 is changed to the fourth speed by operating one of the first to fourth speed clutches 21 to 24 to the transmission side, and the transmission shaft 25 is shifted to the fourth speed. Is transmitted to.

  As shown in FIG. 1, the second main transmission 11 is configured as a hydraulic clutch type in which two hydraulic multi-plate low-speed clutches 26 and a high-speed clutch 27 are arranged in parallel. By operating one of the gears 27 to the transmission side, the power of the transmission shaft 25 is shifted in two stages and transmitted to the auxiliary transmission 12. The sub-transmission device 12 is configured in a synchromesh type for sliding the shift member 53 and can be shifted in two stages, and is mechanically operated by a transmission lever 28 shown in FIG.

[2]
Next, a hydraulic circuit for forward and reverse clutches 5 and 6 and first and second main transmissions 10 and 11 will be described (corresponding to a transmission mechanism).
As shown in FIG. 3, an electromagnetic proportional valve 35 for forward and reverse clutches 5 and 6 and pilot operated switching valves 36a and 37a and pilots for first-speed to fourth-speed clutches 21 to 24 are connected to an oil passage 30 from a pump 29. Operative switching valves 31a, 32a, 33a, 34a and electromagnetic proportional valves 38, 39 for the low speed and high speed clutches 26, 27 are connected.

  As shown in FIG. 3, a pilot operated switching valve 42 a for a hydraulic clutch 41 for differential lock operation in the front wheel differential device 18 and an oil pressure for differential lock operation in the rear wheel differential device 13 are provided in an oil path 40 branched from the oil path 30. A pilot operated switching valve 44a for the clutch 43 and pilot operated switching valves 47a and 48a for the standard clutch 45 and the speed increasing clutch 46 of the front wheel transmission 16 are connected. The switching valves 31a to 34a, 36a, 37a, 42a, 44a, 47a, 48a are urged to the oil discharge side (shutoff side) by springs, and are supplied to the supply side (transmission side) by supplying pilot pressure. Operated.

  As shown in FIG. 3, the pilot oil passage 50 branches from the oil passage 30 through the pressure reducing valve 49, and the pilot oil passage 50 is an operation portion of the switching valves 31 a to 34 a, 36 a, 37 a, 42 a, 44 a, 47 a, 48 a. The electromagnetic operation valves 31b, 32b, 33b, 34b, 36b, 37b, 42b, 44b, 47b, and 48b are connected to the operation unit. The electromagnetic operation valves 31b to 34b, 36b, 37b, 42b, 44b, 47b, and 48b are urged to the oil draining side (shut off side) by springs, and the electromagnetic operation valves 31b to 34b, 36b, 37b, 42b, 44b, When 47b and 48b are operated to the supply side, the pilot pressure is supplied to the operation portion of the switching valves 31a to 34a, 36a, 37a, 42a, 44a, 47a and 48a, and the switching valves 31a to 34a, 36a, 37a, 42a, 44a, 47a and 48a are operated on the supply side (transmission side).

[3]
Next, the structure of the operation part of the forward and reverse clutches 5 and 6 and the first and second main transmissions 10 and 11 will be described.
As shown in FIG. 3, an on-off valve 51 capable of draining the pilot pressure from the operation portion of the switching valves 36a, 37a is provided, and the on-off valve 51 is biased to the closing side by a spring, and the on-off valve 51 is opened. A clutch pedal 52 that is operated to the side is provided. As shown in FIG. 2, a forward / reverse lever 59 that can be operated to a forward position F, a reverse position R, and a neutral position N is provided at the base of the steering handle 58 of the front wheel 19.

  As shown in FIG. 2, the shift lever 28 is swingably supported around the horizontal axis of the maneuvering portion of the airframe, and the shift shaft 54, the shift lever 28, which slides the shift member 53 of the auxiliary transmission 12, Are mechanically linked by a linkage mechanism 55. By operating the shift lever 28 to the neutral position N, the low speed position L, and the high speed position H, the auxiliary transmission 12 (shift member 53) can be operated to the neutral position, the low speed position, and the high speed position. In addition, a position sensor 70 for detecting the operation position of the transmission lever 28 is provided.

  As shown in FIG. 2, a lock pin 56 that can be moved back and forth is provided on the lateral side of the speed change lever 28, and an operation button 57 for moving the lock pin 56 back and forth is provided above the speed change lever 28. . The lock pin 56 is urged to the protruding side (the right side of FIG. 2) by a spring (not shown) (the operation button 57 is also urged to the protruding side to the left side of FIG. 2), and is fixed. By engaging the lock pin 56 with the guide plate 60 of this part, the shift lever 28 is held at the neutral position N, the low speed position L, and the high speed position H. When the operation button 57 is pushed, the lock pin 56 is retracted, and the shift lever 28 can be operated to the neutral position N, the low speed position L, and the high speed position H.

  As shown in FIG. 2, a shift up button 61 (corresponding to a human operation tool) and a shift down button 62 (corresponding to a human operation tool) are arranged on the left lateral side of the speed change lever 28, and the shift up button When 61 and the downshift button 62 are pressed, the first and second main transmissions 10 and 11 are operated as described in [5] below.

  As shown in FIG. 2, whichever of the 7-segment shift display 64 for displaying the shift positions (1st to 8th) of the first and second main transmissions 10 and 11 and the forward and reverse clutches 5 and 6 is the transmission side. The control unit is provided with a neutral lamp 67 indicating that the forward lamp 65 and the reverse lamp 66, the shift lever 28 or the forward / backward lever 59 are operated to the neutral position N. As shown in FIG. 3, a pressure sensor 74 for detecting the operating pressure of the forward and reverse clutches 5 and 6 is provided, and the forward and reverse lamps 65 and 66 are turned on by detection of the pressure sensor 74.

  As shown in FIG. 2, an artificially operated setting lever 68 (corresponding to a selection means) is provided, and the setting lever 68 includes a manual mode position D1, a traveling mode position D2, a load mode position D3, and a traveling setting position. D4 and load setting position D5 are configured to be freely operated. Even if the setting lever 68 is operated to the manual mode position D1, the traveling mode position D2, and the load mode position D3 and the hand is released from the setting lever 68, the setting lever 68 remains in the manual mode position D1, the traveling mode position D2, and the load mode position. Left in D3. When the setting lever 68 is operated to the travel setting position D4 and released, the setting lever 68 automatically returns from the travel setting position D4 to the travel mode position D2, and the setting lever 68 is operated to the load setting position D5. When the hand is released, the setting lever 68 automatically returns from the load setting position D5 to the load mode position D3.

[4]
Next, the operation of the forward / reverse lever 59 will be described with reference to FIG.
When the forward / reverse lever 59 is operated to the forward position F (step S1), an operation current is supplied to the electromagnetic operation valve 36b, the switching valve 36a is operated to the supply side, and the forward clutch 5 is operated to the transmission side (step S2). The forward lamp 65 is lit (step S3). When the forward / reverse lever 59 is operated to the reverse position R (step S1), an operation current is supplied to the electromagnetic operation valve 37b, the switching valve 37a is operated to the supply side, and the reverse clutch 6 is operated to the transmission side (step S4). The reverse lamp 66 is turned on (step S5), and the buzzer 71 shown in FIG. 2 is intermittently operated (step S6).

  When the forward / reverse lever 59 is operated to the neutral position N (step S1), the operation current to the electromagnetic operation valves 36b and 37b is cut off, and the switching valves 36a and 37a are operated to the oil drain side, and the forward and reverse clutches 5 and 6 are operated. Is operated to the shut-off side (step S7), and the neutral lamp 67 is turned on (step S8). When the clutch pedal 52 is depressed, the on-off valve 51 is operated to the open side, the switching valves 36a and 37a are operated to the oil drain side, the forward and reverse clutches 5 and 6 are operated to the cutoff side, and the neutral lamp 67 is lit. . When both the forward and reverse clutches 5 and 6 are operated to the cut-off side in this way, the power is cut off in the forward and reverse clutches 5 and 6 and the airframe is stopped.

[5]
Next, a state where the setting lever 68 is operated to the manual mode position D1 will be described with reference to FIG. 5 (corresponding to manual transmission means).
When the setting lever 68 is operated to the manual mode position D1, the manual mode is set. As shown in FIG. 1, the first main transmission 10 can shift to 4 speeds, and the second main transmission 11 can shift to 2 speeds. Therefore, the first and second main transmissions 10 and 11 can shift to 8 speeds. The speed can be changed. With the low speed clutch 26 operated to the transmission side, the 1st to 4th clutches 21 to 24 correspond to the 1st to 4th shift positions, and the high speed clutch 27 is operated to the transmission side, The first to fourth speed clutches 21 to 24 correspond to the shift positions of the fifth speed to the eighth speed.

  As shown in FIGS. 2 and 3, each of the 1st to 4th speed clutches 21 to 24 and the low speed and high speed clutches 26 and 27 are provided with pressure sensors 63 and 74 for detecting the operating pressure. , 74 are detected, and the current shift positions (first to eighth gears) of the first and second main transmissions 10 and 11 are detected, and the detected shift positions are displayed on the shift display unit 64.

  In the above state, it is assumed that the up-shift button 61 or the down-shift button 62 is pressed (steps S11 and S12). In this case, as shown by a solid line A1 (time point B1) in FIG. 6, when the shift-up button 61 is pressed (step S11), the 1st to 4th clutches 21 that are one speed higher than the current shift position are located. To 24 are started to be operated to the transmission side by the electromagnetic operation valves 31b to 34b (step S13). When the downshift button 62 is pressed (step S12), the first to fourth speed clutches 21 to 24, which are one step lower than the current shift position, are started to be operated to the transmission side by the electromagnetic operation valves 31b to 34b. (Step S14).

  When the speed change lever 28 is operated to the low speed position L or the high speed position H (step S15), it is operated to the transmission side almost simultaneously with steps S13 and S14, as indicated by a solid line A2 (time point B1) in FIG. The operating pressure of the low speed or high speed clutch 26, 27 is operated from the operating pressure P2 in the transmission state to the predetermined low pressure P3 by the electromagnetic proportional valves 38, 39 (step S16). In this case, when operating from the fourth speed shift position to the fifth speed shift position, the operating pressure of the low speed clutch 26 is operated to zero, and the operating pressure of the high speed clutch 27 is operated from zero to the predetermined low pressure P3. Conversely, when operating from the fifth speed shift position to the fourth speed shift position, the operating pressure of the high speed clutch 27 is operated to zero, and the operating pressure of the low speed clutch 26 is operated from zero to the predetermined low pressure P3.

  As shown by a solid line A1 (time point B2 to time point B3) in FIG. 6, the operating pressures of the first to fourth speed clutches 21 to 24 on the first-stage high speed side or the first-stage low speed side are transmitted by electromagnetic operation valves 31b to 34b. The operating pressure P1 is started. At the same time, as indicated by a one-dot chain line A3 in FIG. 6 (from time B2 to time B3), the operating pressures of the first to fourth speed clutches 21 to 24 before the push operation of the shift up button 61 or the shift down button 62 are The operating valves 31b to 34b start to be operated from the operating pressure P1 in the transmission state to zero (step S17).

  When the speed change lever 28 is operated to the low speed position L or the high speed position H (step S18), the operating pressure of the low speed or high speed clutches 26, 27 is changed as shown by the solid line A2 (time point B3 to time point B4) in FIG. The electromagnetic proportional valves 38 and 39 are gradually operated from the predetermined low pressure P3 to the pressure increasing side (step S19). As a result, the power of the first-speed to fourth-speed clutches 21 to 24 on the first-stage high-speed side or the first-stage low-speed side starts to be transmitted via the low-speed or high-speed clutches 26 and 27. When the pressure sensor 63 detects that the operating pressure of the low-speed or high-speed clutches 26 and 27 has reached the operating pressure P2 in the transmission state, as shown at time B4 of the solid line A2 in FIG. 6 (step S20), a shift is performed. It is determined that the speed change operation by pressing the up button 61 or the shift down button 62 is completed, the speed change position after the speed change operation is displayed on the speed change display section 64 (step S21), and the buzzer 71 is activated only once. The operator is notified of the end of the speed change operation (step S22). As a result, the process proceeds to step S11, and a speed change operation by the next pressing operation of the upshift button 61 or the downshift button 62 becomes possible.

When the transmission lever 28 is operated to the neutral position N, the sub-transmission device 12 (shift member 53) is operated to the neutral position, so that the airframe is stopped. When the shift-up button 61 or the shift-down button 62 is pushed and operated in the state where the shift lever 28 is operated to the neutral position N (steps S11 and S12), the first and second main transmissions 10 and 11 (1 The high-speed to fourth-speed clutches 21 to 24, the low-speed and high-speed clutches 26 and 27) are operated to the first-stage high-speed side or the first-stage low-speed side (steps S13, S14, and S17). 64 (step S21), the buzzer 71 is activated only once (step S22).
In this case, since the aircraft is stopped, the operation to the predetermined low pressure P3 of the operating pressure of the low speed or high speed clutch 26, 27 and the operation to the operating pressure P2 in the transmission state are not performed as in steps S16 and S19. .

[6]
Next, a state in which the first and second main transmissions 10, 11 are automatically operated to the high speed side in a state where the setting lever 68 is operated to the travel mode position D2 will be described based on FIG.
When the setting lever 68 is operated to the travel mode position D2, a travel mode assuming road travel is set. As shown in FIGS. 1 and 2, a hand accelerator lever 73 capable of artificially setting the accelerator opening of the engine 1 to an arbitrary position is provided, and a potentiometer type opening for detecting the operation position of the hand accelerator lever 73 is provided. A degree sensor 75 is provided, and an engine speed sensor 72 for detecting the actual engine speed N2 is provided. The rotational speed and opening of the engine 1 in a no-load state (a state in which the forward and reverse clutches 5 and 6 are operated to the cutoff side and the PTO clutch 3 is operated to the cutoff side and no load is applied to the engine 1). The relationship with the detection value of the sensor 75 (the operation position of the hand accelerator lever 73) is obtained in advance, and the engine 1 in the no-load state is determined by the detection value of the opening sensor 75 (the operation position of the hand accelerator lever 73). Is determined as the set rotational speed N1 of the engine 1.

  As described in [5], the timer starts counting in the state where the first and second main transmissions 10 and 11 are operated by the up-shift button 61 or the down-shift button 62 (step S31). The set rotational speed N1 of the engine 1 is detected (step S32), and the actual rotational speed N2 of the engine 1 is detected (step S33). Thereby, the set rotational speed N1 of the engine 1 is equal to or higher than the first predetermined rotational speed N4 (eg, 1200 rpm) (step S34), and the rotational speed difference between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is set. The value N3 (for example, 100 rpm) or less (step S37), and the state where the hand accelerator lever 73 is not operated (step S38) is maintained for a set time (for example, 2 seconds) (step S39) (in this case, The set rotational speed N1 of the engine 1 is a fourth predetermined rotational speed N7 (for example, 2400 rpm) or higher (step S35), and the actual rotational speed N2 of the engine 1 is a fifth predetermined rotational speed N8 (for example, 2300 rpm) or higher (step S36). Then, the process proceeds from step 34 to step S38, bypassing step S37).

  As described above, when the states of steps S34, S37, and S38 are maintained for a set time (for example, 2 seconds) (step S39), steps S13, S16, S17, and S19 to S22 of FIG. The first and second main transmissions 10, 11 are operated to the first high speed side (step S45). When the set rotational speed N1 of the engine 1 detected in step S32 is equal to or higher than the first predetermined rotational speed N4 (for example, 1200 rpm) and lower than the second predetermined rotational speed N5 (for example, 1400 rpm) (step S41), the step of FIG. S13, S16, S17, and S19 to S22 are performed only once (steps S42 and S45). In this case, when the first and second main transmissions 10 and 11 have reached the eighth speed position (step S40), steps S13, S16, S17, and S19 to S22 of FIG. 5 are not performed.

  As described above, after the first and second main transmissions 10 and 11 are operated to the first high speed side (steps S42 and S45), the states of steps S34, S37, and S38 are set to a set time (for example, 2 seconds). When the engine speed is maintained for a long time (step S39), the set rotational speed N1 of the engine 1 detected in step S32 is equal to or higher than the second predetermined rotational speed N5 (for example, 1400 rpm) and lower than the third predetermined rotational speed N6 (for example, 1600 rpm). If present (step S41), steps S13, S16, S17, S19 to S22 of FIG. 5 are performed, and the first and second main transmissions 10, 11 are operated to the first high speed side (steps S43, S45). (The first and second main transmissions 10, 11 are operated to the two-stage high speed side with respect to the aforementioned steps S42, S45). In this case, if the first and second main transmissions 10 and 11 have reached the eighth speed position (step S40), steps S13, S16, S17, and S19 to S22 of FIG. 5 are not performed.

  As described above, after the first and second main transmissions 10 and 11 are operated to the first high speed side (steps S41, S43, and S45), the states of steps S34, S37, and S38 are further set for a set time (for example, 2 seconds). ) (Step S39), if the set rotational speed N1 of the engine 1 detected in step S32 is equal to or higher than a third predetermined rotational speed N6 (for example, 1600 rpm) (step S41), FIG. Steps S13, S16, S17, and S19 to S22 are performed, and the first and second main transmissions 10 and 11 are operated to the first-speed side (steps S44 and S45) (in contrast to the aforementioned steps S42 and S45) Thus, the first and second main transmissions 10 and 11 are operated to the three-speed side). In this case, when the first and second main transmissions 10 and 11 have reached the eighth speed position (step S40), steps S13, S16, S17, and S19 to S22 of FIG. 5 are not performed.

[7]
Next, a state in which the first and second main transmissions 10, 11 are automatically operated to the low speed side in a state where the setting lever 68 is operated to the travel mode position D2 will be described based on FIG.
As described in [6] above, in the state where the first and second main transmissions 10 and 11 are automatically operated to the high speed side, the timer starts counting (step S51), and the set rotation of the engine 1 is started. The number N1 is detected (step S52), and the actual engine speed N2 is detected (step S53). Accordingly, the set rotational speed N1 of the engine 1 is equal to or lower than the sixth predetermined rotational speed N9 (for example, 1000 rpm) (step S54), and the actual rotational speed N2 of the engine 1 is equal to or lower than the seventh predetermined rotational speed N10 (for example, 2300 rpm) (step S55). ) Assume that the state where the hand accelerator lever 73 is not operated (step S56) is maintained for a set time (for example, 0.75 seconds) (step S57).

  As described above, when the states of steps S54, S55, and S56 are maintained for a set time (for example, 0.75 seconds) (step S57), steps S14, S16, S17, and S19 to S22 of FIG. 5 are performed. Thus, the first and second main transmissions 10, 11 are operated to the first-stage low speed side (step S59). As described above, after the first and second main transmissions 10 and 11 are operated to the first low speed side (step S59), the states of steps S54, S55, and S56 are further set at a set time (for example, 0.75 seconds). If maintained for a long time (step S57), steps S14, S16, S17, S19 to S22 of FIG. 5 are performed, and the first and second main transmissions 10, 11 are operated to the first-stage low speed side ( Step S59).

  In this case, as described above, even if the first and second main transmissions 10 and 11 are repeatedly operated to the first stage low speed side, as described in [5] and [6] above, the upshift button 61 or When the first and second main transmissions 10 and 11 have been operated by pressing the downshift button 62 (step S58), steps S14, S16, S17, and S19 to S22 in FIG. Not done.

  As shown in FIG. 9, when the clutch pedal 52 is depressed, the on-off valve 51 is operated to the open side, the switching valves 36a and 37a are operated to the oil drain side, and the forward and reverse clutches 5 and 6 are moved to the cutoff side. When operated (step S71), the timer starts counting (step S72), the operating pressures of the forward and reverse clutches 5 and 6 are detected (step S73), and as shown in FIGS. The rotational speed of the cylindrical shaft 7 is detected by the rotational speed sensor 69 provided on the lower side of the reverse clutches 5 and 6 (step S74).

  As a result, the operating pressure of the forward and reverse clutches 5 and 6 is zero (step S75), and the rotational speed of the cylindrical shaft 7 is equal to or lower than the eighth predetermined rotational speed N11 (for example, 1000 rpm) (step S76). If maintained for (for example, 0.75 seconds) (step S77), it is determined that the aircraft has stopped or the velocity of the aircraft has become extremely low, and the first and second main transmissions 10, 11 are It is automatically operated to the fifth speed shift position (corresponding to a predetermined low speed position for starting) (step S78).

  As shown in [3] and FIG. 2, when the setting lever 68 is held at the travel setting position D4 for a set time, the travel setting mode is entered. As described above, when the travel setting mode is set, in the travel mode described in [6] (FIG. 7), the first predetermined rotational speed N4 (eg, 1200 rpm) in step S34 and the fourth predetermined rotational speed in step S35. N7 (for example, 2400 rpm), the fifth predetermined rotational speed N8 (for example, 2300 rpm) in step S36, the set value N3 (for example, 100 rpm) in step S37, the set time (for example, 2 seconds) in step S39, and the like can be changed.

  Similarly, in the above-described travel mode (FIG. 8), the sixth predetermined rotation speed N9 (eg, 1000 rpm) in step S54, the seventh predetermined rotation speed N10 (eg, 2300 rpm) in step S55, and the set time (eg, 0) in step S57. .75 seconds) can be changed. Similarly, in the above-described travel mode (FIG. 9), the eighth predetermined rotation speed N11 (eg, 1000 rpm) in step S76, the set time (eg, 0.75 seconds) in step S77, and the like can be changed. The fifth speed shift position in step S78 can be changed to another low speed shift position.

[8]
Next, a state in which the first and second main transmissions 10, 11 are automatically operated to the low speed side in the state where the setting lever 68 is operated to the load mode position D3 will be described with reference to FIGS. A description will be given (corresponding to automatic transmission means).
When the setting lever 68 is operated to the load mode position D3, the load mode is set. The shift lever 28 is operated to the low speed position L or the high speed position H (step S91), the forward / reverse lever 59 is operated to the forward position F (step S92), the engine 1 is operating (step S93), and the front wheel 19 The steering angle is within the range of the right and left set angles from the straight-ahead position (step S94) (the aircraft is not turning slightly), and the hand accelerator lever 73 is not operated (step S95). (For example, the state in which the change speed of the set rotational speed N1 of the engine 1 is within a range of ± 50 rpm / 100 milliseconds), the operating pressure of the low speed or high speed clutch 26, 27 is the operating pressure P2 in the transmission state ( Step S96), a shift operation by pressing the up-shift button 61 or the down-shift button 62 described in [5] above, or a change in [8] and [9] described later. Operation and is in the state it is finished (step S97), the process proceeds to step S101.

  When the process proceeds to step S101, a deceleration-side count number KD and an acceleration-side count number KU, which will be described later, are reset, a set rotational speed N1 of the engine 1 is detected (step S102), and an actual rotational speed N2 of the engine 1 is detected. Is detected (step S103), and the actual change speed V1 of the rotational speed N2 of the engine 1 is detected (step S104). Accordingly, when the set rotational speed N1 of the engine 1 is equal to or higher than the ninth predetermined rotational speed N12 (for example, 1300 rpm) (step S105) and smaller than the tenth predetermined rotational speed N13 (for example, 1600 rpm) (step S106), the process proceeds to step S107. To do.

  In step S107, the rotational speed difference between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is not less than the set value N14, and the change speed V1 is not more than a predetermined change speed V11 (for example, 10 rpm / 200 milliseconds). (Step S108) If the shift positions of the first and second main transmissions 10 and 11 are not the lower limit position E2 (corresponding to a predetermined range) of [10], which will be described later (Step S109), the process proceeds to Step S110. Transition. In this case, the set value N14 is set based on the set rotational speed N1 of the engine 1 as indicated by a one-dot chain line A4 in FIG.

In this case, the difference in rotational speed between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is equal to or greater than the set value N14 (step S107), and the actual rotational speed N2 of the engine 1 is reduced. Is shown.
If the change speed V1 is a positive value, it means that the actual engine speed N2 is increasing. If the change speed V1 is a negative value, the actual engine speed N2 is reduced. It means that As a result, the change speed V1 falls below a predetermined change speed V11 (for example, 10 rpm / 200 milliseconds) (step S108), and the actual engine speed N2 hardly changes (the change speed V1 is a positive value). ) Or a state in which the actual rotational speed N2 of the engine 1 decreases (change speed V1 is a negative value).

  When the process proceeds to step S110 as described above, the count number K1 is set based on the difference between the predetermined change speed V11 and the change speed V1 (steps S111, S112, S113, S114). As shown in FIG. 14, “0”, “V12 (negative value)” and “V13 (negative value smaller than V12)” are set with respect to the predetermined change speed V11, and 0 at the predetermined change speed V11 or less. As described above, four regions of less than 0 V12 or more, less than V12 V13 or more, and less than V13 are set, and the count number K1 is “0”, “KK1”, “KK2”, “ KK3 ". In this case, the magnitude relationship is 0 <KK1 <KK2 <KK3.

Next, when the rotational speed difference between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is equal to or larger than a set value N15 (for example, 1.5 times N14) (step S115), the count number K2 is “ KK4 "(KK4 is greater than KK3) (step S116), and the rotational speed difference between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is set to a set value N15 (for example, N14 of 1.5). If it is less than (times) (step S115), the count number K2 is set to "0" (step S117). In this case, the set value N15 is set based on the set rotational speed N1 of the engine 1, as indicated by a one-dot chain line A5 in FIG.
When the count numbers K1 and K2 are set as described above, the count numbers K1 and K2 are added to the count number KD on the deceleration side (step S118).

  By repeating steps S102 to S118 as described above, the count numbers K1 and K2 are added to the count number KD on the deceleration side, the count number KD on the deceleration side increases, and the count number KD on the deceleration side 5 reaches the deceleration-side set count KD1 (step S119), steps S14, S16, S17, and S19 to S22 of FIG. 5 are performed, and the first and second main transmissions 10, 11 are moved to the low speed side by one stage. It is operated (step S120).

  In this case, in the standard state, it takes about 0.75 seconds for the deceleration-side count KD to reach the deceleration-side set count KD1. As the change speed V1 becomes smaller than the predetermined change speed V11 as in steps S112, S113, and S114, the count number K1 is set to be larger. As in steps S115 and S116, the actual rotational speed N2 of the engine 1 is set. When the value greatly decreases, the count number K2 is set to a large value, and the count number KD on the deceleration side quickly reaches the set count KD1 on the deceleration side, so that the first and second main transmissions 10, 11 are slowed down by one stage. The operation timing to the side becomes earlier.

Conversely, if there is no difference between the predetermined change speed V11 and the change speed V1 as in step S111, the count number K1 is set to “0”, and the actual engine speed N2 of the engine 1 as in steps S115 and S117. Is not decreased so much, the count number K2 is set to “0”, so that the count number KD on the deceleration side reaches the set count KD1 on the deceleration side later, and 1 of the first and second main transmissions 10, 11 The operation timing to the low speed side is delayed.
When the change speed V1 becomes larger than the predetermined change speed V11 (for example, 10 rpm / 200 milliseconds) as in step S108, it is determined that the actual rotational speed N2 of the engine 1 is increasing, and the process proceeds to step S101. The count number KD on the deceleration side is reset.

  In step S105, in a state where the set rotational speed N1 of the engine 1 is smaller than the ninth predetermined rotational speed N12 (for example, 1300 rpm), the actual rotational speed N2 of the engine 1 crosses the eleventh predetermined rotational speed N21 (for example, 1500 rpm). If it has decreased (step S121), steps S14, S16, S17, and S19 to S22 of FIG. 5 are performed regardless of the count number KD on the deceleration side, and the first and second main transmissions 10 and 11 are moved to the first stage. It is operated to the low speed side (step S122).

[9]
Next, a state in which the first and second main transmissions 10, 11 are automatically operated to the high speed side when the setting lever 68 is operated to the load mode position D3 will be described with reference to FIGS. (Equivalent to automatic transmission means).
In step S106 of the previous item [8], when the set rotational speed N1 of the engine 1 is equal to or higher than a tenth predetermined rotational speed N13 (for example, 1600 rpm), the shift positions of the first and second main transmissions 10 and 11 will be described later. If it is not the limit position E3 (corresponding to the predetermined range) of [10] on the high speed side (step S131), the process proceeds to step S132.

  When the routine proceeds to step S132, a rotational speed difference between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is detected, and the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 are detected. If the rotational speed difference is less than or equal to a set value N16 (for example, 130 rpm), it is determined that the actual rotational speed N2 of the engine 1 is increasing. In this case, the set value N16 is set based on the set rotational speed N1 of the engine 1, as indicated by a one-dot chain line A6 in FIG. If the rotational speed difference between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is equal to or less than a set value N16 (for example, 130 rpm) (step S132), the set rotational speed N1 of the engine 1 and the actual rotational speed N2 The count number K3 is set (steps S135, S136, and S137) based on the rotational speed difference from the rotational speed N2 of the engine 1 (step S133).

  As shown in FIG. 16, N17, N19, and N20 are set for the rotational speed N18 corresponding to the set value N16, and the relationship is such that N17 <N18 <N19 <N20. Thereby, five areas of N20 or more, less than N20, N19 or more, less than N19, N18 or more, less than N18, N17 or more, and less than N17 are set. Thus, the count number K3 is set to “KK6”, “KK7”, and “KK8” (steps S135, S136, and S137) depending on which region the actual rotational speed N2 of the engine 1 enters (step S133). In this case, “KK6”, “KK7”, and “KK8” are positive values and have a relationship of magnitude of KK6 <KK7 <KK8.

  When the rotational speed difference between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is larger than a set value N16 (for example, 130 rpm) (step S132), the actual rotational speed N2 of the engine 1 is less than N18. If it is in the area of N17 or more (step S134), the count number K3 is set to "-KK5" (step S138). In this case, “−KK5” is a negative value.

  When the count number K3 is set in this way, the count number K3 is added to the count number KU on the speed increasing side (step S139). In this case, when the count numbers K3 “KK6”, “KK7”, and “KK8” are added to the count number KU on the speed increasing side, the count number KU on the speed increasing side increases, and the count number on the speed increasing side count number KU. When K3 “−KK5” is added, the count number KU on the speed increasing side decreases.

  By repeating steps S102 to S139 as described above, the count number K3 is added to the count number KU on the acceleration side, and the count number KU on the acceleration side is increased, and the count number on the acceleration side is increased. When KU reaches the set count KU1 on the speed increasing side (step S140), steps S13, S16, S17, S19 to S22 of FIG. 5 are performed, and the first and second main transmissions 10, 11 are one-stage high speed. (Step S141).

  In this case, in a standard state, it takes about 2.0 seconds for the speed-up count number KU to reach the speed-up side set count KU1. As in steps S135, S136, and S137, as the actual engine speed N2 is larger than the engine speed N18 corresponding to the set value N16 (the engine 1 set engine speed N1 and the actual engine 1 engine speed N2). (The smaller the difference in the rotation speed becomes smaller than the set value N16), the larger the count number K3 is set. Thereby, the count number KU on the speed increasing side reaches the setting count KU1 on the speed increasing side earlier, and the operation timing of the first and second main transmissions 10, 11 to the first speed side becomes earlier.

On the contrary, as shown in step S138, when the actual engine speed N2 becomes smaller than the engine speed N18 corresponding to the set value N16 (the rotation speed between the engine 1 set engine speed N1 and the actual engine 1 engine speed N2). When the number difference becomes larger than the set value N16), the count number K3 is set to a negative value “−KK5”, so that the count number KU on the acceleration side reaches the set count KU1 on the acceleration side later, The operation timing of the first and second main transmissions 10 and 11 toward the first-speed side is delayed.
If the actual rotational speed N2 of the engine 1 is smaller than N17 (see FIG. 16) as in step S134, it is determined that the actual rotational speed N2 of the engine 1 has not increased, and the process proceeds to step S101 and increases. The count number KU on the fast side is reset.

[10]
Next, a case where the setting lever 68 is operated to the travel setting position D4 and the load setting position D5 will be described.
As shown in FIG. 2, when the setting lever 68 is operated to the travel setting position D4 and held for a set time, the travel setting mode is set. In the state in which the travel setting mode is set, the number of times that the first and second main transmissions 10 and 11 in steps S42, S43, S44, and S45 of FIG. The shift up button 61 and the shift down button 62 can be arbitrarily changed. In the previous item [7] and step S78 of FIG. 9, the shift position at which the first and second main transmissions 10, 11 are automatically operated is arbitrarily set to the fifth speed by the shift up button 61 and the shift down button 62. The shift position can be changed to another shift position.

  As described in [8] and [9] above, when the first and second main transmissions 10 and 11 are automatically operated to the low speed side and the high speed side when the load mode is set, The second main transmissions 10 and 11 are operated within the range of the limit positions E2 and E3 on the low speed side and the high speed side (steps S109 and S131). A reference shift position is set, a shift position on the first low speed side of the reference shift position is set as a limit position E2 on the low speed side, and a shift position on the first high speed side of the reference shift position is set as a limit position E3 on the high speed side. Is set.

  As shown in FIG. 2, when the setting lever 68 is operated to the load setting position D5 and held for a set time, the load setting mode is set. In the state in which the load setting mode is set, the reference shift position can be arbitrarily changed to the low speed side and the high speed side by the shift up button 61 and the shift down button 62. Similarly, the shift position on the second low speed side of the reference shift position is set as the limit position E2 on the low speed side, and the shift position on the second high speed side of the reference shift position is set as the limit position E3 on the high speed side. Furthermore, the limit positions E2 and E3 on the low speed side and the high speed side can be arbitrarily changed to the low speed side and the high speed side by the shift up button 61 and the shift down button 62.

[11]
Next, the operation of the auxiliary transmission 12 using the transmission lever 28 will be described.
When the transmission lever 28 is operated to the neutral position N, the sub transmission 12 (shift member 53) is operated to the neutral position, and when the transmission lever 28 is operated to the low speed position L, the sub transmission 12 (shift member 53) is moved to the low speed position. When the shift lever 28 is operated to the high speed position H, the auxiliary transmission 12 (shift member 53) is operated to the high speed position.

  For example, when the forward / reverse lever 59 is operated to the forward position F (the forward clutch 5 is operated to the transmission side and the reverse clutch 6 is operated to the disengagement side), the transmission lever 28 is moved to the low speed position L (high speed position H). In the operating state (the state in which the speed change lever 28 is held at the low speed position L (high speed position H) by the operation button 57 and the lock pin 56), the operation pin 57 is pressed to operate the lock pin 56 to the guide plate 60. When the retraction operation is performed, the switching valve 36a is operated to the oil discharge side by the electromagnetic operation valve 36b, and the forward clutch 5 is operated to the cutoff side.

  As a result, the shift lever 28 is operated from the low speed position L (high speed position H) to the neutral position N and the high speed position H (low speed position L) while the operation button 57 is pressed, and the operation button 57 is returned. The shift lever 28 is held at the neutral position N and the high speed position H (low speed position L) by the lock pin 56.

  In this case, when the operation button 57 is returned at the neutral position N of the shift lever 28, the switching valve 36a is operated to the supply side by the electromagnetic operation valve 36b, and the forward clutch 5 is immediately operated to the transmission side by the electromagnetic proportional valve 35. The When the operation button 57 is returned at the high speed position H (low speed position L) of the speed change lever 28, the switching valve 36a is operated to the supply side by the electromagnetic operation valve 36b, and the forward clutch 5 is gradually transmitted by the electromagnetic proportional valve 35. Operated on the side.

  In a state where the forward / reverse lever 59 is operated to the reverse position R (a state where the reverse clutch 6 is operated to the transmission side and the forward clutch 5 is operated to the disengagement side), the operation button 57 of the speed change lever 28 is depressed as described above. When the push and return operations are performed, the reverse clutch 6 is operated to the disengagement side and the transmission side as described above.

[First Alternative Embodiment of the Invention]
In [8] of [Best Mode for Carrying Out the Invention], the following items (1), (2), and (3) may be added to steps S91 to S97 in FIG.
(1) When a link mechanism (not shown) provided at the rear part of the machine body (to which a working device (for example, a rotary tiller or plow) is connected) is driven to rise above a predetermined height, a step The process does not move to S101.
(2) If an ascending operation is performed to drive the link mechanism to the upper limit position at once, the process does not proceed to step S101.
(3) In the front wheel transmission 16 of FIG. 1, when the speed increasing clutch 46 is operated to the transmission side, the process does not proceed to step S101. When the front wheel transmission 16 is set to the operating state, if the front wheel 1 is steered to the right and left set angles with the straight drive position in between, the standard clutch 45 is operated to the transmission side and the front wheels 19 and When the rear wheel 14 is driven at substantially the same speed and the front wheel 1 is steered more than the right and left set angles, the speed increasing clutch 46 is operated to the transmission side and the front wheel 19 is faster than the rear wheel 14. Driven. When the front wheel transmission 16 is set to the stop state, the standard clutch 45 is operated to the transmission side and the speed increasing clutch 46 is not operated to the transmission side regardless of the steering operation of the front wheel 1.

[Second Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] [First Alternative Embodiment of the Invention], the following (1), (2), (3), and (4) may be adopted.
(1) In [8] of [Best Mode for Carrying Out the Invention] and in step S110 of FIG. 12, the number of counts is not set based on the difference between the predetermined change speed V11 and the change speed V1. The configuration is such that K1 is set proportionally.
(2) In [8] in [Best Mode for Carrying Out the Invention] and in steps S111, S112, S113, S114, S116, and S117 of FIG. 12, the count numbers K1 and K2 are not set, but the deceleration side The setting count KD1 is increased or decreased.
(3) In [9] of [Best Mode for Carrying Out the Invention] and in steps S132 and S133 of FIG. 15, the region is not set, but the rotational speed N18 corresponding to the set value N16 and the actual engine 1 The count number K3 is set proportionally based on how far the rotational speed difference from the rotational speed N2 is far from the set value N16.
(4) Instead of setting the count number K3 in [9] in [Best Mode for Carrying Out the Invention] and steps S135, S136, S137, and S138 in FIG. 15, the setting count KU1 on the acceleration side is increased or decreased. To be configured.

[Third Another Embodiment of the Invention]
In the above-mentioned [Embodiment of the invention] [First alternative embodiment of the invention] [Second alternative embodiment of the invention], the auxiliary transmission 12 shown in FIG. A hydraulic multi-plate type low speed clutch (not shown) and a high speed clutch (not shown) are arranged in parallel, and an electromagnetic proportional valve (not shown) is provided for each of the low speed and high speed clutch of the auxiliary transmission 12. May be provided. If comprised in this way, the 1st-2nd main transmission apparatus 10 and 11 and the subtransmission apparatus 12 will set the 1st-16th speed shift position, and push the upshift button 61 and the downshift button 62 will be pushed. By operating, the first and second main transmissions 10 and 11 and the auxiliary transmission 12 are configured to be operated to the 1st to 16th speed shift positions.

[Fourth Embodiment of the Invention]
In the above-mentioned [Embodiment of the Invention] [First Alternative Embodiment of the Invention] to [Third Alternative Embodiment of the Invention], the first and second main transmissions 10, 11 shown in FIG. The first and second main transmissions 10 and 11 are configured in a gear transmission type in which a shift member (not shown) is slid in the same manner as the auxiliary transmission 12, and the shift member is a hydraulic cylinder. It may be configured to operate by sliding (not shown).
The work vehicle in which the first and second main transmissions 10 and 11 are configured to be capable of shifting to 10 stages or 6 stages, and the auxiliary transmission 12 is configured to be capable of shifting to 3 stages of a high speed position, a medium speed position, and a low speed position. The present invention can also be applied to a working vehicle in which the first and second main transmissions 10, 11 are configured as hydrostatic or belt-type continuously variable transmissions.

Schematic diagram showing the transmission system of the mission case The figure which shows the linkage state of a shift lever, a shift up button, a shift down button, a setting lever, and each part Hydraulic circuit diagram of forward and reverse clutches, first and second main transmissions, etc. Diagram showing the flow of control when operating the forward / reverse lever The figure which shows the flow of control at the time of pushing and operating a shift up button and a shift down button in manual mode The figure which shows the state of the 1st-4th clutch, the low speed, and the high speed clutch at the time of pushing and operating a shift up button and a shift down button in manual mode The figure which shows the flow of control in the state in which the 1st and 2nd main transmission is automatically operated by the high speed side in driving | running | working mode. The figure which shows the flow of control in the state in which the 1st and 2nd main transmission is automatically operated by the low speed side in driving | running | working mode. The figure which shows the flow of control in the state in which the 1st and 2nd main transmission is automatically operated to the 5th gear position in driving mode. The figure which shows the flow of the first half of control in the state in which the 1st and 2nd main transmission is automatically operated by the low speed side and the high speed side in load mode. The figure which shows the flow of the second half of the control in the state in which the 1st and 2nd main transmission is automatically operated by the low speed side and the high speed side in load mode. The figure which shows the flow of control in the state in which the 1st and 2nd main transmission is automatically operated to the low speed side in load mode. A diagram showing the relationship between the set engine speed and the set value The figure which shows the state near the predetermined change speed in load mode The figure which shows the flow of control in the state in which the 1st and 2nd main transmission is automatically operated by the high speed side in load mode. The figure which shows the state in the vicinity of the rotation speed corresponding to a setting rotation speed of an engine, a setting value, and a setting value in load mode

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 10,11 Traveling transmission 61,62 Artificial operation tool 68 Selection means E2, E3 Predetermined range

Claims (3)

A traveling transmission, and a transmission mechanism for operating the traveling transmission.
Automatic transmission means for operating the transmission for traveling from the reference shift position to the low speed side and the high speed side by the speed change mechanism according to the load applied to the engine;
A traveling shift structure for a work vehicle, wherein the reference shift position can be artificially changed. A manual operation means that is manually operated, a manual transmission means that operates a traveling transmission device by a transmission mechanism based on an operation of the artificial operation tool, a manual mode and an automatic transmission means that operate the manual transmission means; Selection means capable of artificially selecting the operating load mode,
2. The traveling speed change structure for a work vehicle according to claim 1, wherein a reference speed change position can be changed by the manual speed change means.   The automatic transmission means is configured to operate the traveling transmission device to a low speed side within a predetermined range from a reference transmission position, and operate the traveling transmission device to a high speed side within a predetermined range from the reference transmission position. 3. A traveling speed change structure for a work vehicle according to claim 1 or 2.

Images