JP5045288B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle having excellent traveling performance in a farm field.

Agricultural, architectural, and transport work vehicles include left and right traveling axles and a transmission that shifts the driving force of the traveling axle. This type of transmission includes turning on and off engine power. There is known a configuration in which a power transmission mechanism including a main clutch to be performed, a main transmission for shifting engine power, and an auxiliary transmission is provided.
Japanese Patent Laying-Open No. 2005-212665

  In the configuration of Patent Document 1, it is unclear how the switching timing of the main transmission is set depending on the shift position of the auxiliary transmission. Therefore, there is a possibility that a shift shock may occur when the main transmission is switched depending on the sub-shift position.

  Accordingly, an object of the present invention is to provide a work vehicle having improved shift controllability when the speed stage can be changed with a sub-shift lever.

The above-mentioned problem of the present invention is solved by the following means.
According to the first aspect of the present invention, in a work vehicle including a hydrostatic continuously variable transmission (7) that shifts according to a depression amount of an accelerator pedal (9), an engine (3) and the engine (3) A power transmission mechanism including a hydraulic main transmission by electronic control and a manually operated gear slide type sub-transmission, and a manual type that can operate the sub-transmission to a neutral position, a high speed side position, or a low speed side position, respectively. A sub-transmission lever (12) and a hydraulic clutch (51, 52) for switching the main transmission device between a high speed side and a low speed side are provided, and the main transmission device provides a high speed instruction for switching to the high speed side and the low speed side, respectively. Switch (62a) and a low speed switch (62b). When the high speed main transmission switch (62a) is pressed, the high speed side hydraulic clutch (51) is connected, and the low speed main transmission switch (62 ), The low-speed hydraulic clutch (52) is connected. When the sub-shift lever (12) is in the low-speed position, it is faster than the sub-shift lever (12) is in the high-speed position. Control structure for setting a long time required to connect the high speed side hydraulic clutch (51) or the low speed side hydraulic clutch (52), regardless of which of the switch (62a) or the low speed switch (62b) is pressed, Whether the high speed side or the low speed side is (12), if the vehicle speed is equal to or less than a predetermined value, the vehicle speed has exceeded the predetermined value for the switching time of the high speed hydraulic clutch (51) or the low speed hydraulic clutch (52). A work vehicle including a control device (100) having a control configuration that is shorter than the time .

According to the first aspect of the present invention, the high speed switch (62a) or the low speed switch (62b) is greater when the sub transmission lever 12 is in the low speed side position than when the sub transmission lever 12 is in the high speed side position. No matter which button is pressed, the time required to connect the high speed side hydraulic clutch (51) or the low speed side hydraulic clutch (52) is set long, and the auxiliary transmission lever (12) is set to either the high speed side or the low speed side. Even if the vehicle speed is less than or equal to the predetermined value, the switching time of the high speed side hydraulic clutch (51) or the low speed side hydraulic clutch (52) becomes shorter than when the vehicle speed exceeds the predetermined value. (51) or the low-speed hydraulic clutch (52) can be switched smoothly without shock.
Even if the vehicle speed is slow on an uphill, the vehicle can be switched in a short time when shifting down, so that the aircraft can be kept from retreating to a minimum .

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1A is a left side view of a work vehicle that performs multipurpose work, which is an example of a work vehicle, and FIG. 1B is a perspective view showing the arrangement of a brake pedal, an accelerator pedal, and a forward / reverse lever.
A vehicle body of a working vehicle having a riding mode of riding four-wheel drive is operated while steering the front wheels 2 with the steering handle 1 or is operated by steering the front and rear wheels 2 and 6. A diesel engine 3 is mounted on the rear part of the fuselage, a transmission case 14 and the like are integrally connected to the front side of the diesel engine 3, and a rear axle housing (not shown) is provided at the rearmost part of the transmission case 14. The rear wheel 6 is mounted on the part. Further, the rotational speed of the output shaft 27 of the hydrostatic continuously variable transmission (HST) 7 shown in FIG. 2 is changed according to the depression amount of the accelerator pedal 9. At this time, since the HST 7 may be damaged at a low rotational speed, the rotational speed of the engine 3 is maintained at a constant rotational speed equal to or higher than a predetermined rotational speed by an accelerator lever (not shown).

FIG. 2 is a power transmission system diagram in the transmission of the work vehicle of this embodiment, and FIG. 3 is a partially enlarged view of the power transmission system diagram of FIG.
The transmission case 14 has a configuration in which four hollow cases of a front case 15, a connection case 16, an intermediate case 17 (FIG. 2), and a rear case 18 (FIG. 3) are connected, and an input shaft 19 that is pivotally supported by the rear case 18. The power of the engine 3 is input to (FIG. 3), and the rotation of the input shaft 19 is transmitted to the first relay shaft 23 by the speed increasing gears 21 and 22 in the input case 20, and further the gear on the first relay shaft 23. The speed is increased by a speed increasing gear 25, and the hydraulic input shaft 7c of the variable capacity hydraulic pump 7a of the hydrostatic continuously variable transmission (HST) 7 is spline-engaged with the gear 25.

The input case 20 is provided to increase the output rotation of the diesel engine 3 to enable high-speed traveling, and is attached to the inside of the input case 20 using a transmission case of a conventional work vehicle. Thus, since it is set as the structure which accelerates with the input case 20, it becomes unnecessary to raise an engine speed at the time of high-speed driving | running | working, and this can aim at noise reduction and a fuel-consumption improvement from the conventional transmission.
Further, the rotational speed of the output shaft 27 of the constant capacity hydraulic motor 7b is changed by the swash plate (trunnion shaft) of the variable capacity hydraulic pump 7a linked to the accelerator pedal 9.

On the other hand, since the PTO drive shaft 26 is directly connected to the hydraulic input shaft 7c inside the variable displacement hydraulic pump 7a of the HST 7, it has a constant rotational speed, that is, the same rotational speed as the hydraulic input shaft 7c of the HST variable displacement hydraulic pump 7a. Rotate with.
The PTO drive shaft 26 is directly connected to a drive shaft 28 having a gear 29, and the power of the gear 31 meshing with the gear 29 is transmitted to the counter gear 33 on the counter shaft 32 after the PTO, and then via the PTO clutch 34. The PTO counter counter shaft 35 passes through the front case 15 and is transmitted to a PTO counter shaft and a PTO counter gear (not shown) integrated with the PTO pre counter shaft 35. Power is output to a PTO on / off gear on a PTO output shaft (not shown).

  Further, the driving force of the travel output shaft 27 of the HST 7 can be transmitted to the large gear 42 and the middle gear 43 on the main transmission shaft 41 via the gear 40a of the transmission shaft 40 through the gear 40b and the gear 40c sequentially. It is. Further, a sub gear high speed small gear 44 a and a sub gear low speed large gear 44 b are provided on the main transmission shaft 41 adjacent to the middle gear 43, and further, a sub transmission low speed gear 44 b adjacent to the main transmission shaft 41. Is provided with a front wheel drive gear 37.

  On the clutch shaft 45 provided in parallel with the main transmission shaft 41, there are provided a transmission clutch gear 46 and a gear 47 that are always meshed with the large gear 42 and the intermediate gear 43, respectively. A hydraulic clutch 51 and a hydraulic clutch 52 are provided on the clutch shaft 45 between them, and a differential device 53 is connected to the output side of the clutch shaft 45, and the front end of the front wheel output shaft ( Power is transmitted to (not shown), and the front wheel 2 is driven.

The hydraulic clutch 51 and the hydraulic clutch 52 are connected by pressing main transmission switches 62a and 62b provided at the top of the auxiliary transmission lever 12 shown in FIG.
When the main transmission switch 62a ("+" sign side) and the main transmission switch 62b ("-" sign side) are pressed, the high speed solenoid 69 and the low speed solenoid 68 shown in FIG. 51 and the hydraulic clutch 52 are respectively connected.

  As shown in FIG. 4, when the auxiliary transmission lever 12 is operated on the high speed side or the low speed side in the lever guide 64, the high speed side auxiliary transmission lever sensor 65H and the low speed side auxiliary transmission lever sensor 65L are respectively connected. The shift position of the auxiliary transmission lever 12 can be detected.

  When the engine 3 is started, either one or both of the forward / reverse lever 10 and the auxiliary transmission lever 12 are set to the neutral position. Start (starter does not rotate) except in the neutral position.

During forward travel (1st speed and 2nd speed), first, the forward / reverse lever 10 is set to the forward side. Next, the first speed (low working speed) and the second speed (high working speed) can be selected. The first gear is used for snow removal work with a snow remover. However, it can also be used for other operations. Also, snow removal work may be performed at the second speed. The second speed is particularly suitable for lawn mowing work with a lawn mower, but it can also be used for other work, and the lawn mowing work may be performed at the first speed. Moreover, the operation | work with mounting | wearing a street cleaner (rotary brush) may also be performed by 1st speed or 2nd speed.
When the auxiliary transmission lever 12 is moved to the low speed side, the auxiliary transmission gear 48b meshes with the gear 44b and preparation for power transmission is completed.

  In the case of the first speed, the switch 62b is turned on to connect the main transmission hydraulic clutch 52, and the power transmission from the gear 43 to the gear 47 is ready. In the case of the second speed, the switch 62a is turned on to connect the main transmission hydraulic clutch 51 to prepare for transmission of the driving force from the gear 42 to the gear 46. Since the switches 62b and 62a function even when the auxiliary transmission lever 12 is neutral, the auxiliary transmission lever 12 may be operated at a low speed or a high speed after the switch 62b or 62a is turned on first. .

  Further, when the accelerator pedal 9 is depressed, the vehicle starts traveling. Corresponding to the depression amount of the accelerator pedal 9 (detected by the position sensor 71), the trunnion shaft of the variable hydraulic pump 7a of the hydraulic continuously variable transmission (HST) 7 is rotated by the motor 66.

  By rotating the trunnion shaft, the rotational power of the engine 3 is output from the output shaft 27 of the constant capacity hydraulic motor 7b of the hydraulic continuously variable transmission (HST) 7, and the obtained power is output to the output shaft 27, the transmission shaft. 40, the gear 40a, the gear 40b, the gear 40c, and the main transmission shaft 41 are transmitted.

As for the power of the main transmission shaft 41, when the hydraulic clutch 52 is connected, the first speed is output, and the power is sequentially transmitted to the gear 43, the gear 47, the hydraulic clutch 52, and the shaft 45. In the case of the second speed to which the hydraulic clutch 51 is connected, power is transmitted to the gear 42, the gear 46, the hydraulic clutch 51, and the shaft 45 in order.
The power of the shaft 45 is transmitted to the gear 48b, the gear 44b, the gear 37, and the gear 56 in order. Then, the left and right front wheels 2 pass through the differential device 53.

  Further, the PTO drive shaft 26 of the variable hydraulic pump 7a of the HST 7 is always rotated by the rotation of the engine 3 (corresponding to the engine speed) regardless of whether the accelerator pedal 9 is depressed. The power of the PTO drive shaft 26 is transmitted to the gear 29, the gear 31, the gear 33, and the shaft 32. The shaft 32 is always rotating.

  When the PTO hydraulic clutch 34 is connected, the power of the shaft 32 is transmitted to the shaft 35 to drive the work implement. On the other hand, when four-wheel drive is selected, a four-wheel drive lever (not shown) is operated to mesh the gear 60 with the gear 58. Then, the power of the gear 56 is transmitted to the gear 57, the gear 58, the gear 60, and the shaft 61, and further passes through the differential device 53 to drive the rear wheel 6.

  Since the shift by the sub-shift lever 12 is a gear slide type, a shift cannot be performed while traveling. However, even if it is a gear slide type, it is possible to shift while traveling if the synchro is configured.

  Since the output of the main transmission is performed by the connection of the hydraulic clutches 52 and 51, a shift while traveling is possible. Therefore, when the switches 62b and 62a are alternately turned on and off during work travel, switching between the first speed (work low speed) and the second speed (work high speed) can be performed.

  In reverse travel, the forward / reverse lever 10 is switched to the reverse side and the accelerator pedal 9 is depressed to start reverse travel. However, even if the forward / reverse lever 10 is operated backward while the accelerator pedal 9 is stepped forward, the vehicle can travel backward without any problem. This is because when the reverse lever 10 is operated to the reverse side, the trunnion shaft rotates in the reverse direction, so the aircraft is decelerated and stopped and then travels backward. The reverse speed at this time is adjusted by the depression amount of the accelerator pedal 9. That is, the trunnion shaft of the variable hydraulic pump 7a of the hydraulic continuously variable transmission (HST) 7 is rotated in the direction opposite to the forward direction in accordance with the depression amount of the accelerator pedal 9 (detected by the position sensor 71), and the engine 3 Is output from the output shaft 27 of the fixed hydraulic motor 7b of the hydraulic continuously variable transmission (HST) 7 in a reverse rotation to that during forward movement.

  When only the brake pedal 8 is depressed, the disc brakes (not shown) of the front wheels 2 and the rear wheels 6 are activated, and the trunnion shaft becomes neutral. When both the brake pedal 8 and the accelerator pedal 9 are depressed, the function of the brake pedal 8 is activated, and the CPU 100 ignores the signal from the accelerator pedal 9. Further, even if the accelerator pedal 9 is depressed when the forward / reverse lever 10 is in the neutral position, the trunnion shaft is not moved. This is because useless power and electric power are not used.

When forward traveling (3rd speed and 4th speed) is selected, the following traveling control is performed.
That is, the 3rd speed (low speed travel) and the 4th speed (high speed travel) are both low speed and high speed during travel, and basically the work machine is not used, but depending on the conditions, the work machine is used at the 3rd speed. Sometimes work is done. When the auxiliary transmission lever 12 is set to the high speed side, the gear 48a of the auxiliary transmission is engaged with the gear 44a, and preparation for power transmission is completed.

  In the case of the third speed, when the switch 62b is turned on, the hydraulic clutch 52 of the main transmission is connected and preparation for power transmission from the gear 43 to the gear 47 is made. In the case of the fourth speed, the switch 62a is turned on. Then, the hydraulic clutch 51 of the main transmission is connected and preparation for power transmission from the gear 42 to the gear 46 is made.

  In the present embodiment, the amount of rotation of the trunnion shaft of the HST 7 changes in accordance with the amount of depression of the accelerator pedal 9. As shown in the HST control block diagram of FIG. 5, the detected value of the accelerator pedal position sensor 71 changes in accordance with the amount of depression of the accelerator pedal 9, and the forward switching relay R1 in a pulse manner according to the amount of change. This is a system in which the reverse rotation switching relay R2 (at the time of depressing) is operated and the rotation angle of the trunnion shaft is adjusted by the electric motor 66 via the motor drive circuit. Further, when the forward / reverse lever 10 is set to the reverse side and the accelerator pedal 9 is depressed, the reverse switching relay R2 is operated, and when the accelerator pedal 9 is returned, the forward switching relay R1 is operated.

  At this time, when the sub-shift lever 12 is in the low-speed (L) position, either the high-speed switch 62a or the low-speed switch 62b is pressed compared to when the sub-shift lever 12 is in the high speed (H) position. However, the time required to connect the high speed side hydraulic clutch 51 or the low speed side hydraulic clutch 52 is lengthened.

  If the vehicle speed detected by the vehicle speed sensor 74 is below a certain value regardless of whether the sub-shift lever 12 is selected at the low speed side or the high speed side, either the high speed side switch 62a or the low speed side switch 62b is selected. Even when is pressed, the time required to connect the hydraulic clutches 51 and 52 is minimized. In this case, the time required for connection of the hydraulic clutches 51 and 52 is at least substantially the same as that when the auxiliary transmission lever 12 is on the high speed side, or is earlier than when the auxiliary transmission lever 12 is on the high speed side. .

  In this way, the high-speed hydraulic clutch 51 or the low-speed hydraulic clutch 52 can be switched smoothly without shock, and can be switched in a short period when shifting down on an uphill, so that the aircraft can be retracted to a minimum. Can be suppressed.

  Note that the forward / reverse switching of the work vehicle is performed by switching the rotation direction of a trunnion shaft (not shown) of the HST 7 by operating the forward / reverse lever 10 shown in FIG. Further, a road cleaning machine can be attached to a PTO output shaft (not shown) to perform road cleaning, or a snow scraper can be used to remove snow.

  In this embodiment, the position sensor 70 that detects the rotation angle of the trunnion shaft of the HST 7 detects whether the output of the HST 7 is properly performed and feeds back. Conventionally, when the disconnection or short circuit of the trunnion shaft position sensor 70 is detected while the vehicle is running, the vehicle is stopped. In this case, the vehicle can be moved until the trunnion shaft position sensor 70 is repaired or replaced. It was very inconvenient.

  FIG. 5 shows a control block diagram, FIG. 6A shows an operation timing chart of the operation member, and FIG. 6B shows the position of the accelerator pedal 9 and the trunnion shaft position. Shows changes in vehicle speed over time. As shown in FIGS. 6 (a) and 6 (b), the trunnion shaft position sensor is detected during traveling when the depression position of the accelerator pedal 9 is detected and control is performed to position the trunnion shaft at a predetermined position of the corresponding HST 7. When the disconnection or short circuit of 70 is detected, the trunnion shaft is positioned so that the vehicle speed detected by the vehicle speed sensor 74 becomes a predetermined low-speed vehicle speed value. However, if the accelerator pedal 9 is in the neutral position, the trunnion shaft is positioned in the neutral position.

  In this way, it is possible to maintain the handleability of the vehicle at the time of failure by not stopping while ensuring safety at low speed when the trunnion shaft position sensor 70 is abnormal.

  Further, when a disconnection or a short circuit of the trunnion shaft position sensor 70 is detected while the vehicle is traveling, the forward / reverse switching lever 10 for forward / reverse switching (or the forward / reverse switching switch 73 provided at the base of the forward / reverse lever 10) If the trunnion shaft is positioned so that the vehicle speed becomes zero when the auxiliary transmission lever 12 is in the neutral position, the vehicle can be stopped when the trunnion shaft position sensor 70 is abnormal. So you can keep safety.

  Further, when the trunnion shaft position sensor 70 is detected to be disconnected or short-circuited, and the vehicle is stopped, when the auxiliary transmission lever 12 is not in the neutral position and the forward / reverse lever 10 is not in the neutral position, the accelerator If the pedal 9 is depressed and deviated from the neutral position, the trunnion shaft is positioned while detecting the vehicle speed so as to move at a low speed in the forward or reverse direction designated by the forward / reverse lever 10.

  Thus, even when the trunnion shaft position sensor 70 is abnormal, the vehicle can be moved back and forth by operating the forward / reverse lever 10 and the accelerator pedal 9, and the vehicle can be transported to, for example, a repair shop, thereby improving handling.

  At this time, when the trunnion shaft is positioned at the low speed position, safety is maintained by switching to the hydraulic clutch 52 (low speed side) even when the hydraulic clutch 51 (high speed side) is in operation. Can do.

  FIG. 7 shows an explanatory diagram of another embodiment when the accelerator pedal position sensor 71 is abnormal. FIG. 7A is an operation timing chart of the operation member, and FIG. 7B is a diagram illustrating temporal changes in the accelerator pedal position, the trunnion shaft position, and the vehicle speed.

  As shown in FIGS. 7 (a) and 7 (b), when the depression position of the accelerator pedal 9 is detected and control is performed to position the trunnion shaft at a predetermined position of the corresponding HST 7, an accelerator pedal position sensor is detected during traveling. When the disconnection or the short circuit 71 is detected, the trunnion shaft may be positioned at a low speed position (for example, 1/10 of the full stroke).

In this way, it is possible to travel at a low speed when the accelerator pedal position sensor 71 is abnormal, ensuring safety and not stopping the vehicle, thereby improving the handleability of the vehicle at the time of failure.
If the abnormality is detected when the vehicle is stopped, the vehicle remains stopped.
Further, when the accelerator pedal position sensor 71 is abnormal, the trunnion shaft is set to the neutral position when the forward / reverse lever 10 is moved to the neutral position or the sub-transmission lever 12 is moved to the neutral position. It can also be set as the structure which improves safety.

  When the accelerator pedal position sensor 71 is detected to be disconnected or short-circuited, the sub-shift lever 12 is not in the neutral position and the forward / reverse lever 10 is not in the neutral position, and the trunnion shaft position sensor 70 is normal. In this case, the trunnion shaft is controlled so that the vehicle can be moved at a low speed in the forward or backward direction designated by the forward / reverse lever 10, or the trunnion shaft is attached to the low speed position to increase the speed, It can be set as the structure which performs control which switches the low speed hydraulic clutch 51,52 to the low speed side.

  Also in these cases, only the low-speed traveling is possible when the accelerator pedal position sensor 71 is abnormal to ensure safety, and the handling of the vehicle at the time of failure can be improved by not stopping the vehicle.

  Further, in this embodiment, since the rotation angle of the trunnion shaft is set by the electric motor 66 (FIG. 5), the rotation speed of the HST output shaft 27 is between the HST output shaft 27 and the hydraulic clutches 51 and 52. An HST output shaft rotation sensor 75 comprising an optical sensor or the like for detecting the rotation is provided in the vicinity of the gear 40c. The trunnion shaft is moved by the electric motor 66 so that Conventionally, the vehicle speed is detected by the vehicle speed sensor 74. However, particularly when the auxiliary transmission operates at a low speed, the vehicle speed sensor 74 cannot detect the vehicle speed because the speed is too low. However, the HST output shaft rotation sensor 75 can detect the number of rotations that can be felt when a human is moving by detecting the movement of the HST output shaft 27 and stop the slow speed at the neutral position of the trunnion shaft. It was.

When the trunnion shaft driving electric motor 66 is provided, the neutral position of the HST trunnion shaft can be automatically determined by the following method.
That is, in the trunnion shaft neutral position adjustment mode, the electric motor 66 for driving the trunnion shaft is automatically operated, and the sensor 75 detects the position where the HST output shaft 27 starts moving forward and the position where the backward movement starts. The intermediate position is stored in the nonvolatile memory as the trunnion axis neutral position.
Thus, the neutral position of the trunnion shaft can always be set accurately, so that a vehicle with high traveling safety can be obtained.

  According to the present invention, since the traveling control of a work vehicle such as a tractor can be performed with higher accuracy than before, a vehicle with good operability can be obtained.

It is a left view of the work vehicle of the Example of this invention. FIG. 2 is a power transmission system diagram in a transmission of the work vehicle of FIG. 1. FIG. 3 is a partially enlarged view of the power transmission system diagram of FIG. 2. It is a perspective view of the operation part of the subtransmission lever of the working vehicle of FIG. It is a HST control block diagram of the work vehicle of FIG. An operation timing chart of the operation member of the work vehicle in FIG. 1 is shown (FIG. 6A), and FIG. 6B is a diagram showing temporal changes in the pedal position, the trunnion shaft position, and the vehicle speed. An operation timing chart of the operation member of the work vehicle in FIG. 1 is shown (FIG. 7A), and FIG. 7B is a diagram showing temporal changes in the pedal position, the trunnion shaft position, and the vehicle speed.

Explanation of symbols

1 Steering handle 2 Front wheel 3 Diesel engine 6 Rear wheel 7 Hydrostatic continuously variable transmission (HST)
7a Variable displacement hydraulic pump 7b Constant displacement hydraulic motor 7c Hydraulic input shaft 8 Brake pedal 9 Accelerator pedal 10 Forward / reverse lever 12 Sub-shift lever 14 Transmission case 15 Front case 16 Connecting case 17 Intermediate case 18 Rear case 19 Input shaft 20 Input case 21 , 22, 24, 25 Gear 23 First relay shaft 26 PTO drive shaft 27 Output shaft 28 Drive shaft 29, 31 Gear 32 PTO counter counter shaft 33 Counter gear 34 PTO clutch 35 PTO front counter shaft 37 Front wheel drive gear 40 Transmission shaft 40a , 40b, 40c Gear 41 Main transmission shaft (clutch shaft) 42 Large gear 43 Medium gear 44a Sub transmission high speed small gear 44b Sub transmission low speed large gear 45 Clutch shaft 46, 47 Transmission clutch gear 48a Sub transmission high speed gear 48b Small gear for sub-speed low speed 51 High Side hydraulic clutch 52 low-speed hydraulic clutch
53 Differential gear 56 Rear wheel drive gear 57 Counter gear 58 Gear 60 Rear wheel output gear 61 Rear wheel drive shafts 62a, 62b Main shift (high / low switching) switch 64 Lever guide 65H, 65L Sub shift lever sensor 66 Electric motor 68 Low-speed solenoid 69 High-speed solenoid 70 Trunnion shaft position sensor 71 Accelerator pedal position sensor 73 Forward / reverse switching switch 74 Vehicle speed sensor 75 HST output shaft rotation sensor 100 Controller R1 Forward switching relay R2 Reverse switching relay

Claims (1)

In a work vehicle including a hydrostatic continuously variable transmission (7) that shifts according to the amount of depression of an accelerator pedal (9),
Engine (3),
A power transmission mechanism including a hydraulic main transmission by electronic control and a gear slide sub-transmission by manual operation for the power of the engine (3);
A manual auxiliary transmission lever (12) capable of operating the auxiliary transmission device in a neutral position, a high speed side position or a low speed side position;
A hydraulic clutch (51, 52) for switching the main transmission device between a high speed side and a low speed side ,
The main transmission includes a high speed switch (62a) and a low speed switch (62b) for instructing switching to the high speed side and the low speed side, respectively.
When the high-speed main transmission switch (62a) is pressed, the high-speed hydraulic clutch (51) is connected, and when the low-speed main transmission switch (62b) is pressed, the low-speed hydraulic clutch (52) is connected.
When the auxiliary transmission lever (12) is at the low speed side position, the high speed switch (62a) or the low speed switch (62b) is pressed compared to when the auxiliary transmission lever (12) is at the high speed side position. A control configuration for setting a long time required to connect the high speed side hydraulic clutch (51) or the low speed side hydraulic clutch (52);
If the vehicle speed is equal to or less than a predetermined value regardless of whether the auxiliary transmission lever (12) is on the high speed side or the low speed side, the vehicle speed is a predetermined value for the switching time of the high speed side hydraulic clutch (51) or the low speed side hydraulic clutch (52). (100) having a control configuration that is shorter than when exceeding
A work vehicle comprising:

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