JP2006240576A - Traveling shift structure for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute a traveling shift structure for a working vehicle such that a traveling speed of a vehicle body can be suitably set according to working conditions when it is constituted such that a traveling shift device is operated to a low speed side and a high speed side according to load applied to an engine. <P>SOLUTION: The traveling shift structure for the working vehicle is provided with an automatic shift means for operate the traveling shift device 10 to the low speed side and the high speed side in an automatic shift range provided with a predetermined range according to the load applied to the engine 1. The automatic shift range can be changed to a wide side and a narrow side. <P>COPYRIGHT: (C)2006,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 transmission for traveling to a low speed side and a high 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 number of revolutions of the engine increases, the traveling transmission is operated to the high speed side. Thus, when the traveling transmission is operated to the low speed side and the high speed side, the actual engine speed is maintained within the set range (the load on the engine is maintained within the set range).

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

In a work vehicle, it is necessary to 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.
An automatic transmission means is provided that includes a transmission for traveling and operates the transmission for traveling to a low speed side and a high speed side within an automatic transmission range having a predetermined range in accordance with a load applied to the engine. The automatic transmission range can be changed to the wide side and the narrow side.

(Function)
According to the first aspect of the present invention, when the traveling transmission is configured to be automatically operated to the low speed side and the high speed side according to the load applied to the engine, the automatic transmission range having a predetermined range is used. An automatic transmission means is provided for operating the traveling transmission device to the low speed side and the high speed side.
Thus, according to the first feature of the present invention, when the traveling transmission is operated to the low speed side and the high speed side by the automatic transmission means, the traveling transmission apparatus is connected to the low speed side and the high speed side within the automatic transmission range. The travel transmission is not operated to the low speed side and the high speed side beyond the automatic transmission range, and the travel transmission is unnecessarily operated to the low speed side and the high speed side. There is no such thing.

According to the first feature of the present invention, the automatic transmission range can be changed to the wide side and the narrow side. As a result, the automatic transmission range may be changed to the wide side under the working conditions in which the traveling transmission device should be operated to the low speed side and the high speed side over a wide range (the automatic transmission range is widened). Just set). On the contrary, in the working conditions where the traveling transmission device should be operated to the low speed side and the high speed side within a narrow range, the automatic transmission range may be changed to the narrow side (the automatic transmission range should be set to a narrow range). Just fine).

(The invention's effect)
According to the first aspect of the present invention, in the traveling transmission structure of a work vehicle, when the traveling transmission is operated to the low speed side and the high speed side in accordance with the load applied to the engine, the traveling transmission apparatus Is not operated unnecessarily beyond the automatic shift range to the low speed side and the high speed side, and the automatic shift range can be set to an appropriate one according to the work conditions. The driving speed change performance of the car could 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.
An artificial gear shifting operation tool that is artificially operated, and a manual gear shifting unit that operates a traveling transmission device based on an operation of the artificial gear shifting operation tool. A manual selection operation tool configured to be able to select a manual mode in which the manual transmission unit is operated and an automatic mode in which the automatic transmission unit is operated and capable of artificially selecting the manual mode and the automatic mode is provided. The automatic transmission range can be changed to the wide side and the narrow side by the human selection operation tool.

(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.
In general, in a work vehicle, in addition to the automatic transmission means described in the preceding item [I], a manual transmission operation tool that is manually operated, and a manual transmission that operates a traveling transmission device based on the operation of the manual transmission operation tool. And a travel speed change device can be arbitrarily operated via the manual speed change means when the driver operates the manual speed change operation tool. In this case, a manual mode in which the manual transmission means operates and an automatic mode in which the automatic transmission means operate can be selected, and a manual selection operation tool is provided so that the driver can operate the manual selection operation tool manually. A mode and an automatic mode are selected.

Thus, according to the second feature of the present invention, the manual selection operation tool for selecting the manual mode and the automatic mode changes the automatic transmission range to the wide side and the narrow side as described in the preceding section [I]. Therefore, a dedicated operation tool for changing the automatic transmission range to the wide side and the narrow side becomes unnecessary. In this case, according to the second feature of the present invention, after the automatic selection mode is selected by operating the human selection operation tool, the automatic shift range can be changed to the wide side and the narrow side by the human selection operation tool.

(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, the human selection operation tool is used for both manual mode and automatic mode selection, and the automatic shift range is changed to the wide side and the narrow side. After the automatic mode is selected, the automatic transmission range can be changed to the wide side and the narrow side directly by the human selection operation tool, which is advantageous in terms of simplification of the structure and improvement in operability. It was.

[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). And the second main transmission 11, the auxiliary transmission 12, and the rear wheel differential device 13 are transmitted to the rear wheels 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 include a friction plate (not shown) and a piston (
This is a hydraulic multi-plate type combined with (not shown), and is operated to the transmission side by supplying hydraulic oil. 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 and the airframe moves forward. 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 includes four hydraulic multi-plate type first speed clutches 21, 2.
It is configured as a hydraulic clutch type in which the speed clutch 22, the 3rd speed clutch 23 and the 4th speed clutch 24 are arranged in parallel, and can be shifted in four stages, and transmits one of the 1st to 4th speed clutches 21 to 24. By operating to the side, the power of the cylindrical shaft 7 is shifted in four stages and transmitted to the transmission shaft 25.

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, the hydraulic circuit for the forward and reverse clutches 5, 6 and the first and second main transmissions 10, 11 will be described.
As shown in FIG. 3, an electromagnetic proportional valve 35 and pilot operated switching valves 36a and 37a for the forward and reverse clutches 5 and 6 and a 1st to 4th clutch 2 are connected to the oil passage 30 from the pump 29.
Pilot operated switching valves 31a, 32a, 33a, 34a for 1 to 24, 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. Switching valves 31a-34a, 36a, 37
The a, 42a, 44a, 47a, and 48a are urged to the oil drain side (shut-off side) by springs, and are operated to the supply side (transmission side) when the pilot pressure is supplied.

As shown in FIG. 3, the pilot oil passage 50 is branched from the oil passage 30 via the pressure reducing valve 49, and the pilot oil passage 50 is switched to the switching valves 31 a to 34 a, 36 a, 37 a, 42 a, 44 a, 47 a,
48a is connected to the operation unit 48a, and the operation unit includes electromagnetic operation valves 31b, 32b, 33b, 34b.
, 36b, 37b, 42b, 44b, 47b, 48b. Electromagnetic valve 31
b to 34b, 36b, 37b, 42b, 44b, 47b, and 48b are biased toward the oil draining side (shut off side) by springs, and the electromagnetically operated valves 31b to 34b, 36b, 37b, 42b, 44b, and 4b.
When 7b and 48b are operated to the supply side, the pilot pressure is changed over from the switching valves 31a to 34a, 36a, 3
7 a, 42 a, 44 a, 47 a, 48 a, and the switching valves 31 a to 34 a,
36a, 37a, 42a, 44a, 47a, 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. Shift lever 28 in neutral position N,
By operating to the low speed position L and the high speed position H, the sub-transmission device 12 (shift member 53) can be operated to the neutral position, the low speed position, and the high speed position. Is provided. A shift up button 61 (corresponding to an artificial gear shifting operation tool) and a shift down button 6 are provided on the left side surface of the shift lever 28.
2 (corresponding to a man-made gear shifting operation tool) are arranged at the top and bottom, and when the shift up button 61 and the shift down button 62 are pressed, the first and second main transmissions as described in [6] described later. 10 and 11 are operated.

As shown in FIG. 2, which one of the 7 segment type shift display 64 and the forward and reverse clutches 5 and 6 transmit the shift positions (1st to 8th) of the first and second main transmissions 10 and 11 is transmitted. A forward ramp 65 and a reverse ramp 66 that indicate whether the lever is operated to the side, a neutral ramp 67 that indicates that the shift lever 28 or the forward / reverse lever 59 is being operated to the neutral position N are provided in the control unit. 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, a setting switch 68 (corresponding to a human selection operation tool) that is manually operated is provided, and the setting switch 68 is driven in the manual mode position shown in FIG. It is configured to be freely operated at three positions: a mode position and a load mode position pushed in the D2 direction. By pressing the setting switch 68 to the manual mode position, the travel mode position, and the load mode position, the manual mode and the travel mode (to the automatic mode are described) as described in [6] [7] [8] [9] described later. Equivalent) and load mode (equivalent to automatic mode) are set.

[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.
Step S6).

When the forward / reverse lever 59 is operated to the neutral position N (step S1), the electromagnetic operation valves 36b, 3
The operating current to 7b is cut off, 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 (step S7), and the neutral lamp 67 is lit (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, 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, in a state where the forward / reverse lever 59 is operated to the forward position F (a state where 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 set to the neutral position N.
Is operated by the electromagnetic operation valve 36b based on the detection of the position sensor 70.
a is operated to the oil drain side, and the forward clutch 5 is operated to the cutoff side.

Thereafter, when the speed change lever 28 is operated to the low speed position L (high speed position H), the position sensor 70 is operated.
Based on this detection, the switching valve 36a is operated to the supply side by the electromagnetic operation valve 36b, and the forward clutch 5 is gradually operated to the transmission side by the electromagnetic proportional valve 35.
State where the forward / reverse lever 59 is operated to the reverse position R (the reverse clutch 6 is operated to the transmission side,
In the state where the forward clutch 5 is operated to the disengagement side), as described above, the speed change lever 28
Is operated to the neutral position N and the low speed position L (high speed position H), the reverse clutch 6 is operated to the cutoff side and the transmission side in the same manner as the forward clutch 5.

[6]
Next, a state in which the setting switch 68 is pushed to the manual mode position will be described with reference to FIG. 5 (hereinafter referred to as manual transmission means).
When the setting switch 68 is pushed to the manual mode position, the manual mode is set. FIG.
As shown in FIG. 1, the first main transmission 10 can shift to four speeds, and the second main transmission 11 can shift to two speeds, so the first and second main transmissions 10, 11 can shift to eight speeds. Is possible. 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, 1st speed ~
The 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, the first to fourth speed clutches 21 to 24, the low speed and the high speed clutch 2
6 and 27 are provided with pressure sensors 63 and 74 for detecting the operating pressure, and the detection of the pressure sensors 63 and 74 detects the current shift positions of the first and second main transmissions 10 and 11 (
1st speed to 8th speed) are detected, and the detected shift positions of the first and second main transmissions 10 and 11 are displayed on the shift display section 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 the solid line A1 (time point B1) in FIG. 6, when the shift-up button 61 is pressed (step S11), the current shift positions of the first and second main transmissions 10 and 11 are determined. The 1st to 4th clutches 21
24 starts to be operated to the transmission side by the electromagnetic operation valves 31b to 34b (step S13).
When the downshift button 62 is pressed and operated (step S12), the 1st to 4th clutches 21 to 24 on the 1st speed lower side than the current shifting positions of the first and second main transmissions 10 and 11 are
The electromagnetic operation valves 31b to 34b start to be operated to the transmission side (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, 4
When operating from the high 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 a 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, an alternate long and short dash line A3 (from time B2 to time B3 in FIG.
) 1 before the push operation of the shift up button 61 or the shift down button 62
The operating pressures of the first to fourth speed clutches 21 to 24 start to be reduced from the operating pressure P1 in the transmission state to zero by the electromagnetic operation valves 31b to 34b (step S17).

When the speed change lever 28 is operated to the low speed position L or the high speed position H (step S18), as shown by the solid line A2 (time point B3 to time point B4) in FIG.
Is gradually operated from the predetermined low pressure P3 to the pressure increase side by the electromagnetic proportional valves 38 and 39 (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 shift operation by pressing the up button 61 or the shift down button 62 is completed, and the shift positions of the first and second main transmissions 10 and 11 after the shift operation are displayed on the shift display unit 64 (step S21), the buzzer 71 is actuated only once to notify the operator of the end of the shift 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 (steps S15 and S18), the sub transmission 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 High-speed to 4-speed clutches 21 to 24, low-speed and high-speed clutches 26 and 27
) Is operated to the first-stage high speed side or the first-stage low speed side (steps S13, S14, S17), and the shift positions of the first and second main transmissions 10, 11 after the shift operation are displayed on the shift display portion 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. (Steps S15 and S18).

[7]
Next, a state where the setting switch 68 is pushed to the load mode position will be described with reference to FIG.
When the setting switch 68 is pushed to the load mode position, the load mode is set. In the load mode, in plowing work with a plow (not shown) or a subsoiler (not shown),
The first and second main transmissions 10 and 11 are as follows according to the ups and downs of the work site, changes in soil quality, and the like.
Are automatically operated to the low speed side and the high speed side within the automatic transmission range R in the load mode.

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 (step S31).

As described in [12] described later, the automatic transmission range R in the load mode is 2 steps, 3 steps, or 4 steps.
The shift position of the first and second main transmissions 10, 11 when the setting switch 68 is pushed to the load mode position is the limit position on the high speed side of the automatic shift range R in the load mode. RH is set (step S32), and the shift positions of the first and second main transmissions 10 and 11 (the limit position RH on the high speed side of the automatic shift range R in the load mode) are displayed on the shift display section 64 ( Step S33), the shift display 64 is turned on (Step S34).

After step S32, a limit position RL on the low speed side of the automatic transmission range R in the load mode is set based on the width of the automatic transmission range R in the load mode described in [12] described later (step S).
35). For example, when the fourth speed position is set as the limit position RH on the high speed side of the automatic transmission range R in the load mode, if the width of the automatic transmission range R in the load mode is three stages, the automatic transmission in the load mode is the second speed position. The limit position RL on the low speed side of the range R is set. In this case, when the limit position RL on the low speed side of the automatic transmission range R in the load mode is lower than the first speed position (step S
36) The first speed position is set as the limit position RL on the low speed side of the automatic transmission range R in the load mode (step S37).

The actual rotational speed N2 of the engine 1 is detected (step S38), and the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is detected (step S39).
). In this case, if the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is large, the load applied to the engine 1 is large and the actual rotational speed N2 of the engine 1 is large.
If the difference N3 between the set engine speed N1 of the engine 1 and the actual engine speed N2 is small, the load applied to the engine 1 is small and the actual engine 1 It can be determined that the rotational speed N2 has not decreased so much.

As shown in FIG. 13, a first set value N11 and a second set value N12 are set for the rotation speed difference N3 between the set rotation speed N1 of the engine 1 and the actual rotation speed N2 of the engine 1. Thereby, the rotational speed difference N between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1
When 3 becomes equal to or greater than the first set value N11 (step S40), the actual engine speed N
2 can be determined to have greatly decreased, steps S14, S16, S17, and S19 in FIG.
Is performed, and the first and second main transmissions 10 and 11 are operated to the one-stage low speed side (step S).
43).

In this case, whether the set rotational speed N1 of the engine 1 is less than a set value N23 (for example, 1300 rpm) (step S41), or the shift positions of the first and second main transmissions 10 and 11 before the operation are the load mode Is the limit position RL on the low speed side of the automatic transmission range R (step S42).
), The first and second main transmissions 10 and 11 are not operated to the first-stage low speed side, and are held at the shift positions of the first and second main transmissions 10 and 11 before the operation.

When the rotational speed difference N3 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 the second set value N12 (step S40), the actual rotational speed N2 of the engine 1 is significantly reduced. Therefore, steps S13, S16, S17, and S19 in FIG. 5 are performed, and the first and second main transmissions 10 and 11 are operated to the first high speed side (step S4).
6).

In this case, whether the set rotational speed N1 of the engine 1 is less than a set value N26 (for example, 1600 rpm) (step S44), or the shift positions of the first and second main transmissions 10 and 11 before the operation are in the load mode. Is the limit position RH on the high speed side of the automatic transmission range R (step S45).
), The first and second main transmissions 10 and 11 are not operated to the first stage high speed side, and are held at the shift positions of the first and second main transmissions 10 and 11 before the operation.

After steps S40 to S46, the shift positions of the first and second main transmissions 10 and 11 are displayed on the shift display unit 64 (step S47). In this case, the first and second main transmissions 10, 1
When the first shift position is the limit position RH on the high speed side of the automatic shift range R in the load mode, the shift display unit 64 is in a blinking state (steps S48, S49), and the first and second main shifts. If the speed change position of the devices 10 and 11 is not the limit position RH on the high speed side of the automatic speed change range R in the load mode, the speed change display portion 64 is in a blinking state (steps S48 and S50).

As described above, in the load mode, the set speed N1 of the engine 1, the speed difference N3 between the set speed N1 of the engine 1 and the actual speed N2 of the engine 1, the first and second set values N11.
, N12, the first and second main transmissions 10, 11 are automatically operated to the low speed side and the high speed side within the automatic transmission range R in the load mode (this corresponds to the automatic transmission means). .

In this case, in a state where the first and second main transmissions 10 and 11 are automatically operated to the low speed side and the high speed side within the automatic transmission range R in the load mode, the transmission lever 28 is at the low speed position L.
1 to the high speed position H or the high speed position H to the low speed position L. When the setting switch 68 is pushed again to the load mode position, the first and second main transmissions 10 and 1 at that time are operated.
The first shift position is set again as the limit position RH on the high speed side of the automatic shift range R in the load mode, and the process proceeds to step S33.

[8]
Next, the first half of the state in which the setting switch 68 is pushed to the travel mode position will be described with reference to FIG.
When the setting switch 68 is pushed to the travel mode position, the travel mode is set. In the traveling mode, in a traveling operation that travels by pulling a trailer (not shown) or the like, depending on the operation of the hand accelerator lever 73, the actual change in the rotational speed N2 of the engine 1 during climbing, etc., as follows: The first and second main transmissions 10 and 11 are automatically operated to the low speed side and the high speed side within the automatic transmission range R in the travel mode.

Similar to the load mode described in [7] above, the rotation speed of the engine 1 in the no-load state is set to the set rotation speed N1 of the engine 1 based on the detected value of the opening sensor 75 (the operation position of the hand accelerator lever 73). (Step S51). As described in [12] below,
The automatic transmission range R in the running mode is set to 2 steps, 3 steps or 4 steps, and the setting switch 6
The shift positions of the first and second main transmissions 10, 11 when 8 is pushed to the travel mode position are set as the limit position RH on the high speed side of the automatic shift range R in the travel mode (step S5).
2) The shift positions of the first and second main transmissions 10 and 11 (the limit position RH on the high speed side of the automatic shift range R in the travel mode) are displayed on the shift display section 64 (step S53), and the shift display section 6
4 is turned on (step S54).

When the limit position RH on the high speed side of the automatic transmission range R in the travel mode is set, [12
], The limit position RL on the low speed side of the automatic transmission range R in the traveling mode is set (step S55). For example, when the 4th speed position is set as the limit position RH on the high speed side of the automatic transmission range R in the traveling mode, if the width of the automatic transmission range R in the traveling mode is 3 stages, the 2nd speed position is the automatic transmission in the traveling mode. Limit position R on the low speed side of range R
Set as L. In this case, when the limit position RL on the low speed side of the automatic shift range R in the travel mode is lower than the first speed position (step S56), the first speed position is the limit position on the low speed side of the automatic shift range R in the travel mode. It is set as RL (step S57).

The actual rotational speed N2 of the engine 1 is detected (step S58), and the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is detected (step S59).
). In this case, if the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is large, the load applied to the engine 1 is large and the actual rotational speed N2 of the engine 1 is large.
Can be judged to have greatly decreased.

As shown in FIG. 13, a first set value N11 is set for the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1. As a result, the engine 1
The rotational speed difference N3 between the set rotational speed N1 and the actual rotational speed N2 of the engine 1 is a first set value N1.
If it is 1 or more (step S60), it can be determined that the actual engine speed N2 has greatly decreased, so steps S14, S16, S17, and S19 of FIG. 5 are performed, and the first and second main transmissions are performed. 10 and 11 are operated to the one-stage low speed side (step S63).

In this case, whether the set rotational speed N1 of the engine 1 is less than a set value N23 (for example, 1300 rpm) (step S61), or the shift positions of the first and second main transmissions 10, 11 before the operation are determined as the travel mode. Is the limit position RL on the low speed side of the automatic transmission range R (step S62).
), The first and second main transmissions 10 and 11 are not operated to the first-stage low speed side, and are held at the shift positions of the first and second main transmissions 10 and 11 before the operation.

After steps S60 to S63, the shift positions of the first and second main transmissions 10 and 11 are displayed on the shift display portion 64 (step S64). In this case, the first and second main transmissions 10, 1
If the first shift position is the limit position RH on the high speed side of the automatic shift range R in the travel mode, the shift display unit 64 is in a blinking state (steps S65 and S66), and the first and second main shifts. If the speed change position of the devices 10 and 11 is not the limit position RH on the high speed side of the automatic speed change range R in the travel mode, the speed change display section 64 is in a blinking state (steps S65 and S67).

[9]
Next, the second half of the state in which the setting switch 68 is pushed to the travel mode position will be described with reference to FIGS.
In step S60 described in [8], when the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is less than the first set value N11, the hand accelerator lever 73 is If not operated (step S68), the first and second main transmissions 10
, 11 are not operated.

If the hand accelerator lever 73 is operated to the high speed side at a low speed in step S60 described in the preceding item [8] (step S68), the set rotational speed N1 of the engine 1 is set to the set value N28.
In a state of less than (for example, 2400 rpm) (step S69), the set rotational speed N1 of the engine 1 is greater than or equal to the set value N22 (for example, 1200 rpm) and the set value N24 (for example, 1400).
5) (step S70), and when the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is less than a set value N4 (for example, 100 rpm) (step S73), FIG. Steps S13, S16, S17, and S19 are performed, and the first and second
Main transmissions 10 and 11 are operated to the first high speed side (step S75).

Next, when the set rotational speed N1 of the engine 1 is not less than the set value N24 (for example, 1400 rpm) and less than the set value N26 (for example, 1600 rpm) (step S71), the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 The rotation speed difference N3 is a set value N4 (for example, 100 rp
m) (step S73), steps S13, S16, S17, S19 in FIG.
And the first and second main transmissions 10, 11 are further operated to the first high speed side (step S75). Next, the set rotation speed N1 of the engine 1 is set to a set value N26 (for example, 1600 rpm).
) Above the set value N28 (for example, 2400 rpm) (step S72), the engine 1
5 is less than a set value N4 (for example, 100 rpm) (step S73), steps S13, S16, and S in FIG.
17 and S19 are performed, and the first and second main transmissions 10 and 11 are further operated to the first-speed side (step S75).

If the hand accelerator lever 73 is operated to the high speed side at a high speed in step S60 described in the preceding item [8] (step S68), the set rotational speed N1 of the engine 1 is set to the set value N28.
In the state of (for example, 2400 rpm) or more (step S76), the actual rotational speed N2 of the engine 1 is not less than the set value N21 (for example, 1100 rpm) and the set value N23 (for example, 130).
0 rpm) (step S77), steps S13, S16, S17, FIG.
S19 is performed, and the first and second main transmissions 10, 11 are operated to the first high speed side (step S75). Next, the actual rotational speed N2 of the engine 1 is set to a set value N23 (for example, 1300 rp).
m) When the value is less than the set value N25 (for example, 1500 rpm) (step S78), steps S13, S16, S17, and S19 of FIG. 5 are performed, and the first and second main transmissions 10 are performed.
, 11 are further operated to the one-stage high speed side (step S75).

Next, when the actual rotational speed N2 of the engine 1 is not less than the set value N25 (for example, 1500 rpm) and less than the set value N27 (for example, 2300 rpm) (step S79), steps S13, S16, S17, and S19 in FIG. The first and second main transmissions 10 and 11 are further operated to the first higher speed side (step S75). Next, when the actual rotational speed N2 of the engine 1 becomes equal to or higher than a set value N27 (for example, 2300 rpm) (step S80), steps S13, S16, S17, and S19 in FIG. 5 are performed, and the first and second main transmissions are performed. 10 and 11 are further operated to the one-stage high speed side (step S75).

In this case, in steps S68 to S73 and S76 to S80, the shift position of the first and second main transmissions 10 and 11 before the operation is the limit position RH on the high speed side of the automatic shift range R in the travel mode. (Step S74), the first and second main transmissions 10, 11 are not operated to the first stage high speed side, and are held at the shift positions of the first and second main transmissions 10, 11 before the operation. . After the aforementioned steps S68 to S80, the process proceeds to step S64 in FIG.

As described above, in the travel modes described in the preceding paragraphs [8] and [9], the set rotational speed N1 of the engine 1, the actual rotational speed N2 of the engine 1, the set rotational speed N1 of the engine 1 and the actual engine 1
Based on the rotation speed difference N3 with respect to the rotation speed N2, the first set value N11 and the operation of the hand accelerator lever 73, the first and second main transmissions 10 and 11 are within the automatic transmission range R of the travel mode. It is automatically operated to the low speed side and the high speed side (this corresponds to the automatic transmission means).

In this case, when the first and second main transmissions 10 and 11 are automatically operated to the low speed side and the high speed side within the automatic transmission range R in the traveling mode, the transmission lever 28 is moved from the low speed position L to the high speed. When the position switch H is operated from the position H or the high speed position H to the low speed position L, and the setting switch 68 is pressed again to the travel mode position, the first and second main transmissions 10 and 11 at that time are operated.
Is again set as the limit position RH on the high speed side of the automatic transmission range R in the travel mode, and the process proceeds to step S53 in FIG.

[10]
Next, the first and second set values N11 and N12 by the sensitivity adjustment switch 76 (previous item [7] [7]
8] [9]) will be described.
As shown in FIG. 2, a dial-type sensitivity adjustment switch 76 is provided. As shown in FIG. 13, by operating the sensitivity adjustment switch 76, the first set value N11 (solid line A4).
) And the second set value N12 (solid line A5) are set, and the first set value N11 (solid line A) is set.
4) and the second set value N12 (solid line A5), “operation area to high speed side” “standard area”
“Operation area to low speed side” is set.

As a result, as described in [7], [8], and [9], when the rotational speed difference N3 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 first set value N11. ("Low-speed side operation region"), the first and second main transmissions 10, 11 are operated to the first-speed side.
A rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 is a first value.
And between the second set values N11 and N12 (“standard range”), the first and second main transmissions 10 and 11 are not operated on either the low speed side or the high speed side. When the rotational speed difference N3 between the set rotational speed N1 of the engine 1 and the actual rotational speed N2 of the engine 1 becomes equal to or smaller than the second set value N12 (“operation region toward high speed side”), the first and second main transmissions 10 and 11 are operated to the one-stage high speed side.

As shown in FIG. 13, when the sensitivity adjustment switch 76 is operated within the operation range H1, the first
The setting value N11 is maintained at “N35”, and the second setting value N12 is maintained at “N33”. When the sensitivity adjustment switch 76 is operated within the operation range H2, the first set value N11 is maintained unchanged from “N35”, and the second set value N12 is “N33” and “N3”.
Within a small range of “4”, the sensitivity is changed linearly corresponding to the operation position of the sensitivity adjustment switch 76.
In this case, the size relationship is N33 <N34 <N35.

As shown in FIG. 13, when the sensitivity adjustment switch 76 is operated within the operation range H3, the second
The setting value N12 is linearly changed corresponding to the operation position of the sensitivity adjustment switch 76 within the range of “N31” and “N33”. In this case, the relationship is N31 <N33, and the difference between “N31” and “N33” is larger than the difference between “N33” and “N34” (operations). The rate of change of the second set value N12 (solid line A5) in the operating range H3 is larger than the rate of change of the second set value N12 (solid line A5) in the range H2).

As shown in FIG. 13, when the sensitivity adjustment switch 76 is operated within the operation range H4, the second
The set value N12 is set to “0”. As described above, when the sensitivity adjustment switch 76 is operated to the operation range H4 and the second set value N12 is set to [0], the first and second main transmissions 10 and 11 are operated to the high speed side. Will not be done.

As shown in FIG. 13, when the sensitivity adjustment switch 76 is operated in the operation ranges H3 and H4, the first set value N11 corresponds to the operation position of the sensitivity adjustment switch 76 in the range of “N32” and “N35”. Change linearly. In this case, 0 <N31 <N32 <N33 <N34 <N
The difference between “N32” and “N35” is larger than the difference between “N33” and “N34” and the difference between “N31” and “N33”. (
Compared to the rate of change of the second set value N12 (solid line A5) in the operating range H2 and the rate of change of the second set value N12 (solid line A5) in the operating range H3, the first setting in the operating ranges H3 and H4 Value N11 (
The change rate of the solid line A4) is large).

[11]
Next, the first automatic deceleration control and the second automatic deceleration control performed in the load mode and the traveling mode described in [7] [8] [9] will be described.
Agricultural tractors are equipped with a link mechanism (not shown) and a lift arm (not shown) that drives the link mechanism at the rear of the machine body, and work devices (plows, subsoilers, rotary tillers) are provided in the link mechanism. At the end of the work ground, the work device is lifted from the ground to turn.

As a result, when a human operation tool (not shown) for operating the lift arm (for example, a lift lever or a lift switch) is operated to the lift arm's ascent side, or the lift arm is at the upper limit position of the lift range In the load mode (traveling mode) described in [7], [8] and [9], the first and second transmissions 10 and 11 are prohibited from operating on the high speed side, and the first and second transmissions 10 are operated. , 11 are the first predetermined number of reduction stages (in the automatic transmission range R of the load mode (travel mode)) (
It is operated to the low speed side only (see [12] described later) (this corresponds to the first automatic deceleration control).

In this case, the first and second transmissions 10 and 11 operate in the load mode (
When the vehicle is in a state of being operated to the low speed side beyond the limit position RL on the low speed side of the automatic transmission range R of the traveling mode), the operation to the deceleration side of the first and second transmissions 10 and 11 is performed in the load mode ( The vehicle stops at a limit position RL on the low speed side of the automatic transmission range R in the travel mode.

For example, when the hand accelerator lever 73 is operated to the low rotation side during turning or deceleration, the set rotation speed N1 of the engine 1 is less than a set value (for example, 1000 rpm) and the actual rotation speed N2 of the engine 1 is set to a set value ( For example, when the speed is less than 2300 rpm, the first and second transmissions 10 and 11 are on the low speed side by a second predetermined speed (see [12] described later) within the automatic transmission range R of the load mode (travel mode). (This corresponds to the second automatic deceleration control).

In this case, the first and second transmissions 10 and 11 are in the load mode (
When the vehicle is in a state of being operated to the low speed side beyond the limit position RL on the low speed side of the automatic transmission range R of the traveling mode), the operation to the deceleration side of the first and second transmissions 10 and 11 is performed in the load mode ( The vehicle stops at a limit position RL on the low speed side of the automatic transmission range R in the travel mode.

[12]
Next, the state in which the width of the automatic transmission range R of the load mode (travel mode) described in the previous item [7] [8] [9] is set to 2 steps, 3 steps, or 4 steps, and the item [11] described above. A state of setting the first and second predetermined deceleration stages in the first and second automatic deceleration controls will be described with reference to FIG.

In a state where the shift lever 28 is operated to the neutral position N, the setting switch 68 is pushed to the load mode position (D2 direction), and then the setting switch 68 is pushed long in the D2 direction E1 (
When, for example, 3 seconds or more), the buzzer 71 operates only once, and the shift display 64 displays “r” indicating that the load mode is set and blinks (step S81). In this state
The setting mode of the load mode is an indeterminate state. When the setting switch 68 is pushed in the direction D2, and the operation E2 is performed, the shift display section 64 displays “P” indicating that the setting mode is the first automatic deceleration control and blinks. (Step S82) (the setting mode of the first automatic deceleration control is also unconfirmed).

As described above, in the state where the setting mode of the load mode is not confirmed (step S81) and the setting mode of the first automatic deceleration control is not confirmed (step S82), the setting switch 68
Each time E2 is pressed in the D2 direction, the state in which the setting mode of the load mode is not yet confirmed (step S81) and the state in which the setting mode of the first automatic deceleration control is not yet confirmed (step S82) appear alternately. The

As described above, when the setting mode of the load mode is unconfirmed (step S81), when the setting switch 68 is pressed long in the D2 direction E3 (for example, 3 seconds or more), the buzzer 71 is set to 1.
The load mode setting mode is determined (step S83). In step S83, the shift display section 64 displays “2” and blinks, and the shift display section 64 displays “2” and blinks every time the setting switch 68 is pushed in the D2 direction E4. , “3” is displayed and blinking and “4” is displayed and blinking are repeated so as to circulate.

In step S83, when the setting switch 68 is pressed in the direction D2 for a long time E5 (for example, 3 seconds or more), the buzzer 71 is activated only once, and the number (“2” or “ “3” or “4”) is set as the width of the automatic transmission range R in the load mode, and the transmission display portion 64 is turned on (step S84).

As described above, when the setting mode of the first automatic deceleration control is not confirmed (step S82), when the setting switch 68 is pressed in the direction D2 for a long time E6 (for example, 3 seconds or more), the buzzer 7
1 is operated only once, and the setting mode of the first automatic deceleration control is determined (step S85). In step S85, the shift display 64 displays “0” and blinks.
Each time the setting switch 68 is pressed in the direction D2, and the operation E7 is performed, the shift display unit 64 displays “0” and blinks, “1” displays and blinks, “2” displays and blinks. Condition and "
The state of displaying “3” and flashing is repeated so as to circulate.

In step S85, when the setting switch 68 is pressed in the direction D2 for a long time E8 (for example, 3 seconds or longer), the buzzer 71 is activated only once, and the number (“0”) displayed on the shift display 64 at that time. Alternatively, “1”, “2”, or “3”) is set as the first predetermined deceleration stage number, and the shift display unit 64 is turned on (step S86). In this case, when [0] is set as the first predetermined deceleration stage number, the first automatic deceleration control is not performed.

In a state where the shift lever 28 is operated to the neutral position N, the setting switch 68 is pushed to the travel mode position (D1 direction), and then the setting switch 68 is pushed long in the D1 direction E9 (
When, for example, 3 seconds or more), the buzzer 71 is activated only once, and the shift display 64 displays “r” indicating that the travel mode is set and blinks (step S87). In this state
The travel mode setting mode is in an indeterminate state. When the setting switch 68 is pushed in the direction D1, and the operation E10 is performed, the shift display 64 displays “A” indicating that the setting mode is the second automatic deceleration control and blinks. (Step S88) (the setting mode of the second automatic deceleration control is also unconfirmed).

As described above, the setting switch 68 is set in the state in which the setting mode of the travel mode is not determined (step S87) and the setting mode of the second automatic deceleration control is not determined (step S88).
Each time E10 is pressed in the D2 direction, a state in which the travel mode setting mode is unconfirmed (step S87) and a state in which the second automatic deceleration control setting mode is unconfirmed (step S88) appear alternately. The

As described above, in the state where the travel mode setting mode has not yet been determined (step S87), when the setting switch 68 is pressed in the direction D1 for a long time E11 (for example, 3 seconds or more), the buzzer 71 is activated only once, and the travel mode is set. The setting mode is determined (step S89). In step S89, the shift display section 64 displays “2” and blinks, and the shift display section 64 displays “2” and blinks every time the setting switch 68 is pushed in the D2 direction E12. , “3” is displayed and blinking and “4” is displayed and blinking are repeated so as to circulate.

In step S89, the setting switch 68 is pressed in the direction D1 for a long time E13 (for example, 3
2 seconds or more), the buzzer 71 operates only once, and the number (“2”, “3”, or “4”) displayed on the shift display 64 at that time is the width of the automatic shift range R in the travel mode. As a result, the shift display 64 is turned on (step S90).

As described above, when the setting mode of the second automatic deceleration control has not yet been determined (step S88), when the setting switch 68 is pressed long in the D1 direction E14 (for example, 3 seconds or more), the buzzer 71 is activated only once. The setting mode of the second automatic deceleration control is confirmed (step S91).
) In step S91, the shift display unit 64 displays “0” and blinks, and the shift display unit 64 displays “0” and blinks every time the setting switch 68 is pressed in the D1 direction E15. , “1” is displayed and blinking, “2” is displayed and blinking, and “3” is displayed and blinking are repeated so as to circulate.

In step S91, the setting switch 68 is pressed in the direction D1 for a long time E16 (for example, 3
2 seconds or more), the buzzer 71 operates only once, and the number ("0" or "1" or "2" or "3") displayed on the shift display 64 at that time is the second predetermined deceleration. The number of steps is set, and the shift display 64 is turned on (step S92). In this case, when [0] is set as the second predetermined deceleration stage number, the second automatic deceleration control is not performed.

[13]
Next, the automatic shifting of the load mode (or traveling mode) described in the preceding item [12] is performed in the first half of the change of the automatic shifting range R in the load mode (or traveling mode) described in the preceding item [7] [8] [9]. Range R
Will be described with reference to FIG.
When the setting switch 68 is pushed to the load mode position (or the travel mode position) and the shift lever 28 is operated to the neutral position N (step S101), when the upshift button 61 is pushed (step S102), 1 and second main transmissions 10 and 11 are 1
If the shift down button 62 is pushed and operated (step S104) (step S104)
In step S103), the first and second main transmissions 10 and 11 are operated to the first low speed side (step S105). In this case, steps S13, S14, S16, S17, S19 in FIG.
1 to 4 of the current shift positions of the first and second main transmissions 10 and 11 are not performed.
The speed clutches 21 to 24 are immediately operated to the disengagement side, and the current first and second main transmissions 10,
The 1st to 4th speed clutches 21 to 24 on the 1st speed side (or 1st speed side) from the 11th shift position are immediately operated to the transmission side.

As described above, when the first and second main transmissions 10 and 11 are operated to the first-stage high speed side (first-stage low speed side), the shift positions of the first and second main transmission apparatuses 10 and 11 after the operation are changed. The limit position RH on the high speed side of the automatic transmission range R in the load mode (or travel mode) is set (step S106).
), The shift positions (the limit position RH on the high speed side of the automatic shift range R of the load mode (or travel mode)) of the first and second main transmissions 10 and 11 are displayed on the shift display section 64 (step S10).
7) The shift display 64 is turned on (step S108).

When the limit position RH on the high speed side of the automatic transmission range R in the load mode (or traveling mode) is set, it is next based on the width of the automatic transmission range R in the load mode (or traveling mode) described in [12] above. Thus, the limit position RL on the low speed side of the automatic transmission range R in the load mode (or traveling mode) is set (step S109). For example, when the 4th speed position is set as the limit position RH on the high speed side of the automatic transmission range R in the load mode (or traveling mode), the width of the automatic transmission range R in the load mode (or traveling mode) is 3 steps. The second speed position is set as the limit position RL on the low speed side of the automatic transmission range R in the load mode (or travel mode). In this case, when the limit position RL on the low speed side of the automatic transmission range R in the load mode (or travel mode) is lower than the first speed position (step S110), the first speed position is in the load mode (or travel mode). Automatic shift range R
Is set as the limit position RL on the low speed side (step S111).

[14]
Next, the automatic shift of the load mode (or travel mode) described in the previous item [12] in the latter half of the change of the automatic shift range R of the load mode (or travel mode) described in the previous item [7] [8] [9]. Range R
Will be described with reference to FIGS. 11 and 12. FIG.
When the setting switch 68 is pushed to the load mode position (or the travel mode position) and the shift lever 28 is operated to the low speed position L or the high speed position H (step S101), the shift up button 61 is pressed (step S101). S121), the previous item [7] [8] [9]
(The state in which the first and second main transmissions 10, 11 are automatically operated to the low speed side and the high speed side within the automatic transmission range R of the load mode (or travel mode)). Thus, steps S13, S16, S17, and S19 of FIG. 5 are performed, and the first and second main transmissions 10, 1 are performed.
1 is operated to the one-stage high speed side (step S123).

When the downshift button 62 is pressed and operated (step S122), step S1 in FIG.
4, S16, S17, and S19 are performed, and the automatic transmission in the state described in [7], [8], and [9] (the first and second main transmissions 10 and 11 are in the load mode (or the traveling mode)) is performed. In the range R, the first and second main transmissions 10 are prioritized over the state of being automatically operated to the low speed side and the high speed side).
, 11 are operated to the one-stage low speed side (step S127).

When the shift-up button 61 and the shift-down button 62 are pressed, the shift positions of the first and second main transmissions 10, 11 after the operation are displayed on the shift display portion 64 (step S).
131). If the shift position of the first and second main transmissions 10 and 11 after the operation is the limit position RH on the high speed side of the automatic shift range R in the load mode (or travel mode), the shift display section 64 is in a lit state (Steps S132 and S133), and the shift positions of the first and second main transmissions 10 and 11 after the operation are at the limit position RH on the high speed side of the automatic transmission range R in the load mode (or travel mode). If not, the shift display 64 is in a blinking state (steps S132 and S134).
).

In a state in which the shift positions of the first and second main transmissions 10 and 11 are the limit position RH on the high speed side of the automatic transmission range R in the load mode (or travel mode), the upshift button 61 is pressed and operated, When the first and second main transmissions 10 and 11 are operated to the first speed side, the shift position of the first and second main transmissions 10 and 11 is set to the automatic transmission range R in the load mode (or travel mode). It will be in the state which comes off to the high speed side. In such a state (steps S121, S1
23, S124), the shift positions of the first and second main transmissions 10, 11 after the operation are set as the limit position RH on the high speed side of the automatic shift range R in the load mode (or travel mode) (step S125). ).

Next, based on the width of the automatic transmission range R in the load mode (or traveling mode) described in [12], the limit position RL on the low speed side of the automatic transmission range R in the load mode (or traveling mode) is set. (Step S126). For example, when the third to fourth speed positions are set as the limit position RH on the high speed side of the automatic transmission range R in the load mode (or traveling mode), the width of the automatic transmission range R in the load mode (or traveling mode) is 3 If it is, the first gear position to the second gear position is
(Or the travel mode) is set as a limit position RL on the low speed side of the automatic transmission range R (the first and second main transmissions 10 and 11 are on the high speed side of the automatic transmission range R in the load mode (or travel mode)). The first and second main transmissions 10 and 11 are operated to the high speed side while being operated to the limit position RH, and the first and second main transmissions 10 and 11 are operated to the high speed side. The entire automatic transmission range R in the load mode (or travel mode) corresponds to a state in which the entire range is operated on the high speed side).

When the shift position of the first and second main transmissions 10 and 11 is the limit position RL on the low speed side of the automatic shift range R in the load mode (or travel mode), the shift down button 62 is pushed and operated, When the first and second main transmissions 10 and 11 are operated to the one-stage low speed side, the shift position of the first and second main transmissions 10 and 11 changes to the automatic transmission range R in the load mode (or travel mode). It will be in the state which comes off to the low speed side. In such a state (steps S122, S1
27, S128), the shift positions of the first and second main transmissions 10, 11 after the operation are set as the limit position RL on the low speed side of the automatic shift range R in the load mode (or travel mode) (step S129). ).

Next, a limit position RH on the high speed side of the automatic transmission range R in the load mode (or traveling mode) is set based on the width of the automatic transmission range R in the load mode (or traveling mode) described in [12]. (Step S130). For example, when the second speed position to the first speed position are set as the lower limit position RL of the automatic transmission range R in the load mode (or traveling mode), the width of the automatic transmission range R in the load mode (or traveling mode) is 3 If it is, the 4th speed position to the 3rd speed position
(Or the travel mode) is set as a limit position RH on the high speed side of the automatic transmission range R (the first and second main transmissions 10 and 11 are set on the low speed side of the automatic transmission range R in the load mode (or travel mode)). In the state operated to the limit position RL, the first and second main transmissions 10, 11 are operated to the low speed side, and the first and second main transmissions 10, 11 are operated to the low speed side. The entire automatic shift range R in the load mode (or travel mode) corresponds to a state where the entire automatic shift range R is operated on the low speed side).

Next, the shift positions of the first and second main transmissions 10 and 11 after the operation are displayed on the shift display section 64 (step S131), and the first and second main transmissions 10 and 11 after the operation are displayed. If the shift position is the limit position RH on the high speed side of the automatic shift range R in the load mode (or travel mode), the shift display section 64 is in a lit state (steps S132 and S133). If the shift positions of the first and second main transmissions 10 and 11 are not the limit position RH on the high speed side of the automatic shift range R in the load mode (or travel mode), the shift display portion 64 is in a blinking state (step S132). , S134).

[First Alternative Embodiment of the Invention]
In [Best Mode for Carrying Out the Invention] described above, when the sensitivity adjustment switch 76 is operated within the operation range H4 as shown in [10] in the previous section and FIG.
Instead of being set to “0”, the second set value N12 (solid line A5) in the operation range H3 may be configured to extend straight to “0” as it is (for example, in the operation range H4). The left end of the sheet of FIG. 13 is “0”). Thereby, even if the sensitivity adjustment switch 76 is operated in the operation range H4, the “operation area toward the high speed side” is set.

[Second Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] [First Another Mode of Carrying Out the Invention], as described in [10] above, the first and second set values N1 are set by one sensitivity adjustment switch 76.
1 and N12 are not set, but a dedicated sensitivity adjustment switch 76 for setting and changing the first set value N11, and a dedicated sensitivity adjustment switch 76 for setting and changing the second set value N12. May be provided separately, and the first and second set values N11 and N12 may be set and changed independently.

[Third Another Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] [First Alternative Embodiment of the Invention] [Second Alternative Embodiment of the Invention], the sub-transmission device 12 shown in FIG. In the same manner, a hydraulic multi-plate low speed clutch (not shown) and a high speed clutch (not shown) are arranged in parallel, and are proportional to each of the low speed and high speed clutches of the auxiliary transmission 12. You may comprise so that a valve (not shown) may be provided. If comprised in this way, the 1st and 2nd main transmission 10
, 11, and the sub-transmission device 12 set the 1st to 16th gear shift positions. By pushing the shift up button 61 and the shift down button 62, the first and second main transmissions 10, 11. The sub-transmission device 12 is configured so that it can be operated to the 1st to 16th speed shift positions.

[Fourth Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] [First Alternative Embodiment of the Invention] to [Third Alternative Embodiment of the Invention], the first and second main transmissions 10 shown in FIG. 11 is configured as a hydraulic clutch type, but the first and second main transmissions 10 and 11 are configured as a gear transmission type that slide-operates a shift member (not shown) in the same manner as the auxiliary transmission 12 and shifts. You may comprise so that a member may be operated by sliding operation with a hydraulic cylinder (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. Working vehicle,
The present invention can also be applied to a work vehicle in which the first and second main transmissions 10 and 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 switch, 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 in the state which pushed and operated the upshift button and the downshift button in manual mode. The figure which shows the state of the 1st-4th speed clutch at the time of pushing and operating a shift up button and a shift down button in manual mode, a low speed, and a high speed clutch 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 and the high speed side in load mode. The figure which shows the flow of the first 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 driving | running | working mode. The figure which shows the flow of the second 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 driving | running | working mode. The figure which shows the flow of control in the state which sets the width | variety of the automatic transmission range of load mode (driving mode) The figure which shows the flow of the first half of the control in the state which changes the automatic transmission range of load mode (driving mode) The figure which shows the flow of the second half of control in the state which changes the automatic transmission range of load mode (driving mode). The figure which shows the relationship between the operation position of a sensitivity adjustment switch, and the 1st and 2nd setting value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 10 Transmission for driving 61,62 Man-made gear change operation tool 68 Man-made selection operation tool R Automatic transmission range

Claims (2)

Equipped with a transmission for traveling,
An automatic transmission means for operating the transmission for traveling to a low speed side and a high speed side within an automatic transmission range having a predetermined range in accordance with a load applied to the engine;
A traveling speed change structure for a work vehicle configured such that the automatic speed change range can be changed to a wide side and a narrow side. A manual transmission operation tool that is operated artificially, and manual transmission means for operating a traveling transmission device based on the operation of the artificial transmission operation tool,
A manual mode in which the manual transmission means operates and an automatic mode in which the automatic transmission means operate can be selected, and the manual selection operation tool capable of artificially selecting the manual mode and the automatic mode is provided.
2. The traveling speed change structure for a work vehicle according to claim 1, wherein the automatic speed change range can be changed to a wide side and a narrow side by the human selection operation tool.

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