JP2014122650A - Traveling transmission control device of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a traveling transmission control device which enables smooth traveling by backward switching without causing a traveling shock even by the backward operation of a switching lever during the traveling of a working vehicle.SOLUTION: The traveling transmission device of the working vehicle comprises multi-plate type clutches C1, C2 at two systems of a forward-rotation traveling transmission system and a reverse-rotation traveling transmission system, selects one of them according to the start operation of forward/rearward switching lever 43, and performs boosting control by a start boosting characteristic P0 for boosting pressure from neutral pressure up to transmission pressure for a prescribed start connecting time T0, has a backward boosting characteristic P1 for boosting pressure up to the transmission pressure for a backward connecting time T1 longer than the start connecting time T0, and can efficiently perform a repeat or the like of forward/rearward traveling at a prescribed vehicle speed at farmland leveling or the like by boosting and controlling the selection-side clutches C1, C2 by the backward boosting characteristic P1 as far as the operation of the forward/rearward switching lever 43 is in a direction reverse to the traveling direction of the traveling working vehicle.

Description

  The present invention relates to a traveling transmission control device for a work vehicle that performs forward / reverse switching in accordance with an operation of a lever or the like.

  As shown in Patent Document 1, the forward / reverse switching portion of the traveling transmission device of the work machine is provided with a multi-plate clutch in each of two systems of forward rotation and reverse rotation that receive power in common, and is neutral by turning off both clutches. Forward or reverse transmission output by selecting one of them. Each clutch boosts the clutch on the selected side in a predetermined pattern according to lever operation from the neutral position and controls the start, thereby enabling smooth start in the switched forward / backward direction and shifting to traveling at a predetermined vehicle speed. . Therefore, when performing leveling work in a field that repeats forward and backward travel at a predetermined vehicle speed, work efficiently at the predetermined vehicle speed while avoiding sudden start by lever operation in the reverse direction via stop of travel by lever operation to the neutral position. Can proceed.

JP 2003-184990 A

  However, when the work vehicle is traveling, if the lever is operated in the reverse direction without waiting for the travel stop due to the lever operation to the neutral position, the power will be switched to the reverse side power by the corresponding operation of the clutch. Even during traveling, a large traveling shock is unavoidable, and as a result, there is a problem that not only fatigue due to a physical shock of the boarding operator but also a failure is induced by impact on the vehicle equipment.

  An object of the present invention is to provide a field leveling work that repeats forward / reverse travel at a predetermined vehicle speed by enabling travel by smooth reverse switching without causing a travel shock even by a reverse operation of a lever during travel of a work vehicle. An object of the present invention is to provide a travel transmission control device for a work vehicle that can efficiently perform the above.

  According to the first aspect of the present invention, a multi-plate clutch (C1, C2) is provided in each of two forward and reverse traveling transmission systems that receive power in common, and one of the two clutches (C1, C2). Is selected according to the start operation of the forward / reverse switching lever (43), and the start boosting characteristic (P0) for boosting the clutch (C1, C2) from the neutral pressure to the transmission pressure in a predetermined start connection time (T0). In the travel transmission control device for a work vehicle to be boosted, a reverse boosting characteristic (P1) for boosting in a reverse connection time (T1) longer than the start connection time (T0) is provided, and the forward / reverse switching lever (43) is operated. Only when the traveling direction of the work vehicle is traveling is opposite to the traveling direction of the traveling vehicle, the pressure-up control of the clutches (C1, C2) on the selection side is performed by the reverse boosting characteristic (P1).

  In the invention according to claim 2, a multi-plate clutch (C1, C2) is provided in each of two forward and reverse traveling transmission systems that receive power in common, and one of the two clutches (C1, C2). Is selected according to the starting operation of the forward / reverse switching lever (43), and the boosting of the clutch (C1, C2) is increased by increasing the starting connection increment (H0) by a predetermined pressure increase immediately before transmission connection. In the traveling transmission control device for a work vehicle that performs boost control by the characteristic (P0), the reverse boost characteristic (P2) for boosting the connection via the boost of the reverse connection increment (H2) exceeding the start connection increment (H0) is provided. Only when the operation of the forward / reverse switching lever (43) is in the direction opposite to the traveling direction of the traveling work vehicle, the pressure-up control of the clutches (C1, C2) on the selected side is performed by the reverse pressure increasing characteristic (P2). And wherein the door.

  The invention according to claim 3 is the clutch pedal rate according to claim 1 or claim 2, wherein the clutch (C1, C2) connection control is boosted with a predetermined boosting pattern adapted to a smooth clutch engagement operation. A limiter process is provided, and the clutch pedal rate limiter process is applied only when the return speed of the clutch pedal (51) in the stationary state including the slow movement is detected only when the operation speed is lower than a predetermined speed.

  According to the first aspect of the present invention, when the forward / reverse switching lever (43) is started, the selection side clutch (C1, C2) is boosted by a predetermined start boosting characteristic (P0), and the forward rotation and the reverse rotation are performed. When the traveling transmission system of the system is switched and the switching lever (43) is operated backward while the vehicle is traveling, the selection-side clutches (C1, C2) are boosted by the backward boosting characteristic (P1). As a result, the reverse operation during the traveling can smoothly shift to the reverse traveling without causing a large traveling shock while ensuring a quick start traveling by operating the switching lever when the traveling is stopped.

  According to the second aspect of the present invention, when the forward / reverse switching lever (43) is started, the selected clutch (C1, C2) starts with a predetermined pressure increase immediately before the transmission connection due to a predetermined start boosting characteristic (P0). By boosting the connection via boosting of the connection increment (H0), the two traveling power transmission systems of forward rotation and reverse rotation are switched, and when the switching lever (43) is operated backward while the vehicle is traveling, Since the selection side clutch (C1, C2) is controlled by the reverse boosting characteristic (P2) to increase the reverse connection increment (H2) exceeding the start connection increment (H0), the connection boost is suppressed to a small level. In a reverse operation during traveling while ensuring a quick start traveling by the operation, it is possible to smoothly shift to reverse traveling without causing a large traveling shock.

  According to the invention of claim 3, in addition to the effect of claim 1 or 2, the clutch pedal rate limiter process is applied and smooth start control is performed only when the speed of the pedal return operation is slower than the predetermined speed. From this, it is possible to switch between a sudden start and a smooth start depending on the operation speed of the clutch pedal (51), so that it is possible to start reflecting the operator's intention reliably.

Overall side view of the leveling work vehicle of this embodiment Mission case internal configuration diagram Transmission system development diagram Operation equipment layout Control system block diagram Example of clutch connection boost curve Flow chart of reverse rotation control example 1 Other examples of clutch connection boost curves Flow chart of control processing example for safe stop Flow chart of error handling process example Flow chart of an example of abnormality notification processing Flow chart of start control example with clutch pedal Flow chart of another example of control by clutch pedal Flow chart of control example during traveling Work equipment lift control system configuration block diagram Flow chart of working machine lifting control example Flow chart of control example corresponding to work implement rising output Flow chart of control example when work implement is in upper limit position

Hereinafter, embodiments of the present invention will be described with reference to examples shown in the drawings.
A work vehicle to which the present invention is applied is shown in FIG. 1 as a whole side view. Driven so as to be switchable, the work machine W is configured to be driven from the PTO shaft 40 at the rear of the machine body, and these traveling system and work system operating tools are installed in the cabin 9.

(Transmission system)
2 and 3 are a transmission mechanism 13 in the transmission case 12 of the transmission 5 and its transmission diagram. The transmission 5 includes a transmission case 12 and a transmission mechanism 13 that is disposed in the transmission case 12 and transmits rotational power from the engine 4 to the rear wheels 3 and the like. The transmission mechanism 13 transmits the rotational power from the engine 4 to the front wheels 2, the rear wheels 3, and the work equipment attached to the machine body, and drives them with the rotational power from the engine 4.

  Specifically, the transmission mechanism 13 includes an input shaft 14, a forward / reverse switching mechanism 15, a Hi-Lo transmission mechanism 16, a main transmission mechanism 17, an auxiliary transmission mechanism 18, a 2WD / 4WD switching mechanism 19, and a PTO. (Power take-off) It is comprised including the drive mechanism 20 grade | etc.,.

  The transmission mechanism 13 transmits the rotational power generated by the engine 4 to the rear wheel 3 through the input shaft 14, the forward / reverse switching mechanism 15, the Hi-Lo transmission mechanism 16, the main transmission mechanism 17, and the auxiliary transmission mechanism 18 in order. be able to. In addition, the transmission mechanism 13 transmits the rotational power generated by the engine 4 to the input shaft 14, the forward / reverse switching mechanism 15, the Hi-Lo transmission mechanism 16, the main transmission mechanism 17, the auxiliary transmission mechanism 18, and the 2WD / 4WD switching mechanism 19. It can be transmitted to the front wheel 2 via the order. Further, the transmission mechanism 13 can transmit the rotational power generated by the engine 4 to the work machine via the input shaft 14 and the PTO drive mechanism 20 in this order.

  The input shaft 14 is coupled to the output shaft of the engine 4, and the rotational power from the engine 4 is transmitted (input).

(Forward / reverse switching)
The forward / reverse switching mechanism 15 can switch the rotational power transmitted from the engine 4 to forward rotation or backward rotation. The forward / reverse switching mechanism 15 includes a forward gear 15a, a reverse gear 15b, a reverse gear 15c, a hydraulic multi-plate clutch (forward clutch) C1, and a hydraulic multi-plate clutch (reverse clutch) C2.
The hydraulic multi-plate clutches C1 and C2 can switch the power transmission path in the forward / reverse switching mechanism 15 by switching the engaged / released state. The forward / reverse switching mechanism 15 transmits the rotational power transmitted to the input shaft 14 according to the engaged / released state of the hydraulic multi-plate clutches C1 and C2 to the counter shaft 21 by changing the transmission path. When the hydraulic multi-plate clutch C1 is in the engaged state and the hydraulic multi-plate clutch C2 is in the released state, the forward / reverse switching mechanism 15 transmits the rotational power transmitted to the input shaft 14 to the forward gear stage 15a, the hydraulic multi-plate. The torque is transmitted to the counter shaft 21 through the clutch C1 in the forward direction. When the hydraulic multi-plate clutch C1 is in the disengaged state and the hydraulic multi-plate clutch C2 is in the engaged state, the forward / reverse switching mechanism 15 transmits the rotational power transmitted to the input shaft 14 to the reverse gear 15b, the reverse gear 15c, The torque is transmitted to the counter shaft 21 through the hydraulic multi-plate clutch C2 in the reverse direction. Thereby, the forward / reverse switching mechanism 15 can switch the forward / backward movement of the tractor 1.
The forward / reverse switching mechanism 15 also functions as a main clutch. When both the hydraulic multi-plate clutches C1 and C2 are released, a neutral state is established and power transmission to the front wheels 2 and rear wheels 3 is interrupted. be able to. The forward / reverse switching mechanism 15 can switch between forward, reverse, and neutral by hydraulic control by operating the forward / reverse switching lever 43 by an operator, for example. Further, by depressing the clutch pedal 51, both the hydraulic multi-plate clutches C1 and C2 can be released.

  The Hi-Lo speed change mechanism 16 can change the rotational power transmitted from the engine 4 at a high speed stage or a low speed stage. The Hi-Lo transmission mechanism 16 includes a Hi (high speed) side gear stage 16a, a Lo (low speed) side gear stage 16b, a hydraulic multi-plate clutch (Hi (high speed) side clutch) C3, and a hydraulic multi-plate clutch (Lo (low speed) side). Clutch) C4. The hydraulic multi-plate clutches C3 and C4 can switch the power transmission path in the Hi-Lo transmission mechanism 16 by switching the engaged / released state. The Hi-Lo transmission mechanism 16 transmits the rotational power transmitted to the counter shaft 21 to the transmission shaft 22 by changing the transmission path in accordance with the engaged / released state of the hydraulic multi-plate clutches C3 and C4. When the hydraulic multi-plate clutch C3 is in the engaged state and the hydraulic multi-plate clutch C4 is in the released state, the Hi-Lo transmission mechanism 16 transmits the rotational power transmitted to the counter shaft 21 to the hydraulic multi-plate clutch C3, Hi side. The speed is changed via the gear stage 16a and transmitted to the transmission shaft 22. The Hi-Lo transmission mechanism 16 transmits the rotational power transmitted to the counter shaft 21 to the hydraulic multi-plate clutch C4, Lo side when the hydraulic multi-plate clutch C3 is in the released state and the hydraulic multi-plate clutch C4 is in the engaged state. The speed is changed via the gear stage 16 b and transmitted to the transmission shaft 22. As a result, the Hi-Lo transmission mechanism 16 can change the rotational power from the engine 4 at the transmission ratio of the Hi side gear stage 16a or the transmission ratio of the Lo (low speed) side gear stage 16b and transmit it to the subsequent stage. it can. For example, the Hi-Lo speed change mechanism 16 is turned on / off by a worker when a Hi-Lo changeover switch (high / low speed change operation switch) 44 (see FIG. 7) is turned on / off. ) Side can be switched, and the speed can be changed in one of two stages of high speed and low speed. Further, the Hi-Lo speed change mechanism 16 can change speed while the tractor 1 is traveling due to the above-described configuration.

  The main speed change mechanism 17 can change the rotational power transmitted from the engine 4 at any one of a plurality of shift speeds. The main speed change mechanism 17 is a synchromesh type speed change mechanism, and here, the rotational power transmitted from the engine 4 via the forward / reverse switching mechanism 15 and the Hi-Lo speed change mechanism 16 can be changed. The main speed change mechanism 17 includes a first speed gear stage 17a, a second speed gear stage 17b, a third speed gear stage 17c, a fourth speed gear stage 17d, a fifth speed gear stage 17e, and a sixth speed gear as a plurality of speed stages. A stage 17f is included. The main transmission mechanism 17 transmits the rotational power transmitted to the transmission shaft 22 according to the coupling state of the first speed gear stage 17a to the sixth speed gear stage 17f with the transmission shaft 22 from the first speed gear stage 17a to the first speed gear stage 17a. The speed is changed via one of the sixth speed gears 17f and transmitted to the transmission shaft 23. Thus, the main transmission mechanism 17 can shift the rotational power from the engine 4 at any gear ratio of the first speed gear stage 17a to the sixth speed gear stage 17f and transmit it to the subsequent stage. The main speed change mechanism 17 can select and switch one of a plurality of speed stages by operating the main speed change operation lever 45 by an operator, for example, and the first speed gear stage 17a to the sixth speed gear. The speed can be changed at any one of the six stages 17f. Further, the main transmission mechanism 17 can change gears while the tractor 1 is traveling due to the above-described configuration.

  The auxiliary transmission mechanism 18 can change the rotational power transmitted from the engine 4 through the forward / reverse switching mechanism 15, the Hi-Lo transmission mechanism 16, and the main transmission mechanism 17 in order. The sub-transmission mechanism 18 includes a first sub-transmission 24, a second sub-transmission 25, and the like, and the rotational power transmitted to the transmission shaft 23 is transmitted to the first sub-transmission 24 and the second sub-transmission 25. And the like, and then transmitted to the transmission shaft 26. The first sub-transmission 24 can transmit the rotational power transmitted from the engine 4 and shifted by the main transmission mechanism 17 or the like at the high speed stage or the low speed stage and transmit it to the rear wheel 3 side that is the driving wheel. The second sub-transmission 25 shifts the rotational power transmitted from the engine 4 and shifted by the main transmission mechanism 17 or the like at an extremely low speed that is lower than that of the first sub-transmission 24, and is a rear wheel 3 that is a driving wheel. Can be transmitted to the side.

  The first sub transmission 24 of the sub transmission mechanism 18 includes a first gear 24a, a second gear 24b, a third gear 24c, a fourth gear 24d, and a shifter 24e. The first gear 24a is coupled to the transmission shaft 23 so as to be integrally rotatable, and rotational power from the transmission shaft 23 is transmitted (input). The second gear 24b meshes with the first gear 24a. The third gear 24c is coupled to the second gear 24b so as to be integrally rotatable. The fourth gear 24d meshes with the third gear 24c. The shifter 24e switches the coupling state of the first gear 24a, the fourth gear 24d, and the transmission shaft 26. The shifter 24e has a Hi (high speed) side position where the first gear 24a and the transmission shaft 26 are coupled so as to be integrally rotatable, a Lo (low speed) side position where the fourth gear 24d and the transmission shaft 26 are coupled so as to be integrally rotatable, Neither the first gear 24a nor the fourth gear 24d is coupled to the transmission shaft 26 and can move to the neutral position (neutral position) to be released. The first sub-transmission 24 transmits the rotational power transmitted to the transmission shaft 23 to the transmission shaft 26 by switching the transmission path according to the position of the shifter 24e. When the shifter 24e is in the Hi side position, the first auxiliary transmission 24 transmits the rotational power transmitted to the transmission shaft 23 from the first gear 24a to the second gear 24b, the third gear 24c, and the fourth gear 24d. The transmission is transmitted to the transmission shaft 26 without being interposed (transmission is performed from the transmission shaft 23 → the first gear 24a → the transmission shaft 26). When the shifter 24e is in the Lo side position, the first auxiliary transmission 24 transmits the rotational power transmitted to the transmission shaft 23 from the first gear 24a to the second gear 24b, the third gear 24c, the fourth gear 24d, and the shifter. The speed is sequentially reduced via 24e and transmitted to the transmission shaft 26. As a result, the first auxiliary transmission 24 transmits the rotational power from the engine 4 to the Hi (high speed) side gear ratio without passing through the second gear 24b, the third gear 24c, and the fourth gear 24d, or the second gear. 24b, the third gear 24c, and the fourth gear 24d can be shifted at the Lo (low speed) side gear ratio and transmitted to the subsequent stage. Further, when the shifter 24e is in the neutral position, the first auxiliary transmission 24 is in a state where both the first gear 24a and the fourth gear 24d are idle with respect to the transmission shaft 26, that is, in a neutral state. In the first sub-transmission 24, for example, when the first sub-transmission operation lever 49 is operated by an operator, the position of the shifter 24e is switched to switch between the Hi (high speed) side, the Lo (low speed) side, and the neutral. be able to.

  The second subtransmission 25 of the subtransmission mechanism 18 includes a first gear 25a, a second gear 25b, a third gear 25c, a fourth gear 25d, and a shifter 25e. The first gear 25a is coupled to the fourth gear 24d so as to be integrally rotatable. The second gear 25b meshes with the first gear 25a. The third gear 25c is coupled to the second gear 25b so as to be integrally rotatable. The fourth gear 25d meshes with the third gear 25c. The shifter 25e switches the coupling state between the fourth gear 25d and the transmission shaft 26. The shifter 25e has a pole Lo (very low speed) side position where the fourth gear 25d and the transmission shaft 26 are coupled so as to be integrally rotatable, and a neutral position (neutral position) where the fourth gear 25d and the transmission shaft 26 are not coupled and released. Position). The second sub-transmission 25 transmits the rotational power transmitted to the transmission shaft 23 to the transmission shaft 26 by switching the transmission path according to the position of the shifter 25e. When the first sub-transmission 24 is in the neutral state and the shifter 25e is in the pole Lo side position, the second sub-transmission 25 uses the rotational power transmitted to the transmission shaft 23 as the first sub-transmission 24. From the first gear 24a, the second gear 24b, the third gear 24c, the fourth gear 24d, the first gear 25a, the second gear 25b, the third gear 25c, the fourth gear 25d, and the shifter 25e of the second auxiliary transmission 25 are connected. Are sequentially decelerated through and transmitted to the transmission shaft 26. As a result, the second auxiliary transmission 25 converts the rotational power from the engine 4 into the second gear 24b, the third gear 24c, the fourth gear 24d, the first gear 25a, the second gear 25b, the third gear 25c, The speed can be changed at a speed ratio on the pole Lo (very low speed) side via the 4 gear 25d and transmitted to the subsequent stage. Further, when the shifter 25e is in the neutral position, the second auxiliary transmission 25 is in a state where the fourth gear 25d is idling with respect to the transmission shaft 26, that is, in a neutral state. The second sub-transmission 25 is in a neutral state when the first sub-transmission 24 is on the Hi (high speed) side or the Lo (low speed) side. The second auxiliary transmission 25 can switch the position of the shifter 25e by switching the position of the shifter 25e, for example, when the operator operates the second auxiliary transmission operation lever 50, and can switch between the pole Lo (very low speed) side and the neutral.

  Therefore, the subtransmission mechanism 18 combines the rotational power transmitted to the transmission shaft 23 with the first subtransmission 24 and the second subtransmission 25, so that one of the three stages of high speed, low speed, and extremely low speed can be obtained. Either can be changed and transmitted to the transmission shaft 26. That is, the subtransmission mechanism 18 can shift at the Hi (high speed) stage when the first subtransmission 24 is in the Hi (high speed) side and the second subtransmission 25 is in the neutral state. . The subtransmission mechanism 18 can shift at the Lo (low speed) stage when the first subtransmission 24 is in the Lo (low speed) side and the second subtransmission 25 is in the neutral state. When the first sub-transmission 24 is in the neutral state and the second sub-transmission 25 is on the pole Lo (very low speed) side, the sub-transmission mechanism 18 shifts at the pole Lo (very low speed) stage. Can do. The auxiliary transmission mechanism 18 is switched between high speed, low speed, and extremely low speed while the tractor 1 is stopped.

  The transmission mechanism 13 of the transmission 5 transmits the rotational power transmitted to the transmission shaft 26 to the rear wheel 3 via the rear wheel differential 27, the axle (drive shaft) 28, the planetary gear mechanism 29, and the like. As a result, in the tractor 1, the rear wheel 3 is rotationally driven as a drive wheel by the rotational power from the engine 4.

  To summarize the above description, the rotation of the input shaft 14 is first switched to forward rotation or reverse rotation by the forward / reverse switching mechanism 15, and is shifted by the Hi-Lo transmission mechanism 16 in one of two stages of high speed and low speed. The main transmission mechanism 17 is shifted at any one of the six speeds of the first speed gear stage 17a to the sixth speed gear stage 17f, and the auxiliary transmission mechanism 18 is selected from any of the three speeds of high speed, low speed, and extremely low speed. And is transmitted to the axle 28. In other words, the rotation of the input shaft 14 is shifted by any one of 2 × 6 × 3 = 36 stages by the transmission mechanism 13 of the transmission 5 and transmitted to the axle 28.

  The 2WD / 4WD switching mechanism 19 switches whether or not the rotational power transmitted to the transmission shaft 26 is transmitted to the front wheel 2 side. The 2WD / 4WD switching mechanism 19 includes a transmission shaft 19a, a first gear 19b, a second gear 19c, a transmission shaft 19d, and a shifter 19e. The transmission shaft 19a transmits (inputs) the rotational power from the transmission shaft 26 via the gear 30, the gear 31, the transmission shaft 32, the coupling 33, and the like. The transmission gear 19a is inserted into the first gear 19b, and the first gear 19b is assembled so as to be rotatable relative to the transmission shaft 19a. The second gear 19c meshes with the first gear 19b. The transmission shaft 19d is coupled to the second gear 19c so as to be rotatable together. The shifter 19e switches the coupling state between the transmission shaft 19a and the first gear 19b. The shifter 19e is movable to a 4WD position where the transmission shaft 19a and the first gear 19b are coupled so as to be integrally rotatable, and to a 2WD position (neutral position) where the transmission shaft 19a and the first gear 19b are not coupled and released. is there. When the shifter 19e is at the 4WD position, the 2WD / 4WD switching mechanism 19 transmits the rotational power transmitted to the transmission shaft 19a to the transmission shaft 19d via the first gear 19b and the second gear 19c. Thereby, the 2WD / 4WD switching mechanism 19 can transmit the rotational power from the engine 4 to the front wheel 2 side. The transmission mechanism 13 of the transmission 5 transmits the rotational power transmitted to the transmission shaft 19d to the front wheels 2 via the front wheel differential 34, the axle (drive shaft) 35, the vertical shaft 36, the planetary gear mechanism 37, and the like. As a result, the tractor 1 can be driven by four-wheel drive, with the front wheels 2 and the rear wheels 3 being rotationally driven as drive wheels by the rotational power from the engine 4. In the 2WD / 4WD switching mechanism 19, when the shifter 19e is in the 2WD position, the transmission of the rotational power transmitted to the transmission shaft 19a to the transmission shaft 19d side is cut off. As a result, the tractor 1 can travel by two-wheel drive. The 2WD / 4WD switching mechanism 19 can switch between the two-wheel drive and the four-wheel drive by switching the position of the shifter 19e by, for example, operating the 2WD / 4WD switching lever 46 by an operator.

(PTO)
The PTO drive mechanism 20 drives the work machine with the power from the engine 4 by shifting the rotational power transmitted from the engine 4 and outputting it from the PTO shaft 40 at the rear of the machine body to the work machine. The PTO drive mechanism 20 includes a PTO clutch mechanism 38, a PTO transmission mechanism 39, a PTO shaft 40, and the like.

  The PTO clutch mechanism 38 switches between transmission and interruption of power to the PTO shaft 40 side. The PTO clutch mechanism 38 includes a gear 38a, a hydraulic multi-plate clutch C5, and a transmission shaft 38b. The gear 38a meshes with a gear 41 that is coupled to the input shaft 14 so as to be integrally rotatable. The hydraulic multi-plate clutch C5 switches the power transmission state between the gear 38a and the transmission shaft 38b by switching the engaged / released state. The PTO clutch mechanism 38 enters a PTO drive state in which power is transmitted to the PTO shaft 40 side when the hydraulic multi-plate clutch C5 is engaged, and the rotational power transmitted from the input shaft 14 to the gear 38a via the gear 41. Is transmitted to the transmission shaft 38b via the hydraulic multi-plate clutch C5. When the hydraulic multi-plate clutch C5 is released, the PTO clutch mechanism 38 is in a PTO non-driven state (neutral state) in which transmission of power to the PTO shaft 40 side is interrupted, and the rotational power transmitted to the gear 38a is reduced. Transmission to the transmission shaft 38b side is interrupted. The PTO clutch mechanism 38 can switch between a PTO driving state and a PTO non-driving state by hydraulic control, for example, when an operator turns on / off the PTO switching switch 47. The tractor 1 is provided with a gear pump 70 through a gear 70a meshing with the gear 38a, a gear 70b meshing with the gear 70a, and the like. The gear pump 70 applies hydraulic pressure to a hydraulic system such as the transmission mechanism 13.

  The PTO speed change mechanism 39 changes speed when power is transmitted to the PTO shaft 40 side. The PTO speed change mechanism 39 includes a Hi (high speed) side gear stage 39a, a Lo (low speed) side gear stage 39b, a transmission shaft 39c, and a shifter 39d. The PTO transmission mechanism 39 changes the rotational power transmitted to the transmission shaft 38b via the Hi side gear stage 39a or the Lo side gear stage 39b according to the position of the shifter 39d, and transmits it to the transmission shaft 39c. To do. The shifter 39d switches the coupling state of the Hi side gear stage 39a, the Lo side gear stage 39b, and the transmission shaft 39c. The shifter 39d has a Hi (high speed) side position for coupling the Hi side gear stage 39a and the transmission shaft 39c, a Lo (low speed) side position for coupling the Lo side gear stage 39b and the transmission shaft 39c, a Hi side gear stage 39a, None of the Lo-side gear stage 39b is coupled to the transmission shaft 39c and can be moved to the neutral position (neutral position) to be released. When the shifter 39d is at the Hi side position, the PTO transmission mechanism 39 transmits the rotational power transmitted to the transmission shaft 38b to the transmission shaft 39c via the Hi side gear stage 39a. When the shifter 39d is in the Lo side position, the PTO transmission mechanism 39 transmits the rotational power transmitted to the transmission shaft 38b to the transmission shaft 39c via the Lo side gear stage 39b. As a result, the PTO transmission mechanism 39 can shift the rotational power from the engine 4 at the gear ratio of the Hi-side gear stage 39a or the gear ratio of the Lo-side gear stage 39b and transmit it to the subsequent stage. Further, when the shifter 39d is in the neutral position, the PTO transmission mechanism 39 is in a state where both the Hi side gear stage 39a and the Lo side gear stage 39b are idle with respect to the transmission shaft 39c, that is, in a neutral state. In the PTO transmission mechanism 39, for example, when a PTO transmission operation lever 48 described later is operated by an operator, the position of the shifter 39d is switched to switch between the Hi (high speed) side, the Lo (low speed) side, and the neutral. The speed can be changed in one of two stages, high speed and low speed.

  The PTO shaft 40 is coupled to a work machine and transmits rotational power from the engine 4 to the work machine. The PTO shaft 40 is rotationally driven by the rotational power transmitted to the transmission shaft 39c being transmitted through the first gear 41, the second gear 42, and the like.

  In summary, the rotation of the input shaft 14 is transmitted to the PTO speed change mechanism 39 via the PTO clutch mechanism 38, and the PTO speed change mechanism 39 changes the speed in one of two stages of high speed and low speed. , Transmitted to the PTO shaft 40, and the PTO shaft 40 is rotationally driven. As a result, the tractor 1 can change the rotational power transmitted from the engine 4 and output it from the PTO shaft 40 to the work implement, thereby driving the work implement.

(Operation control section)
As shown in FIG. 4, the tractor 1 is provided with various operation levers in the cabin 9 or in the rear part 1R of the machine body. In the cabin 9, the tractor 1 is provided with a forward / reverse switching lever 43, a Hi-Lo switching switch 44, a main transmission operating lever 45, a 2WD / 4WD switching lever 46, and a PTO switching switch 47. Further, the tractor 1 is provided with a PTO speed change operation lever 48 at the rear part 1R of the airframe. The forward / reverse switching lever 43 is used to perform the forward / reverse switching operation of the forward / reverse switching mechanism 15, and when the operator operates the forward / backward switching lever 43, the forward / backward switching mechanism 15 moves forward, backward, and neutral. Can be switched. The Hi-Lo changeover switch 44 is used to perform a Hi-Lo shift operation (high / low speed change operation) of the Hi-Lo transmission mechanism 16, and when the operator operates the Hi-Lo changeover switch 44, the Hi-Lo changeover switch 44 is operated. The speed change mechanism 16 can be switched between high speed and low speed. The main transmission operation lever 45 is used to perform the main transmission operation of the main transmission mechanism 17, and when the operator operates the main transmission operation lever 45, the main transmission mechanism 17 is moved from the first speed gear stage 17 a to the sixth gear stage. Any one of the six speed gear stages 17f can be switched to neutral. The 2WD / 4WD switching lever 46 performs the 2WD / 4WD switching operation of the 2WD / 4WD switching mechanism 19, and the operator operates the 2WD / 4WD switching lever 46 to move the 2WD / 4WD switching mechanism 19 to the two wheels. It can be switched between driving and four-wheel driving. The PTO changeover switch 47 is used to perform a clutch changeover operation of the PTO clutch mechanism 38, and an operator operates the PTO changeover switch 47 to switch the PTO clutch mechanism 38 between the PTO drive state and the PTO non-drive state. Can do. The PTO speed change operation lever 48 is used to perform the PTO speed change operation of the PTO speed change mechanism 39. By operating the PTO speed change operation lever 48, the operator can switch the PTO speed change mechanism 39 to high speed, low speed, and neutral. it can.

  The tractor 1 of the present embodiment includes a first sub-transmission operation lever 49 that performs a first sub-transmission operation of the first sub-transmission 24 of the sub-transmission mechanism 18 and a second sub-transmission 25 of the sub-transmission mechanism 18. The second sub-shift operation lever 50 that performs the second sub-shift operation is provided separately, thereby improving versatility. Both the first auxiliary transmission operation lever 49 and the second auxiliary transmission operation lever 50 are provided in the cabin 9. The tractor 1 according to the present embodiment adds a gear position (for example, an extremely low speed gear) by adding a second sub-transmission 25 to the first sub-transmission 24 in a retrofit manner in the sub-transmission mechanism 18, for example. A second sub-transmission operation lever 50 that is configured to be capable of operating a shift speed by adding the second sub-transmission 25 is provided separately from the first sub-transmission operation lever 49.

(Control system)
As shown in the block diagram of FIG. 5, the control system is composed of a clutch pedal sensor 51p for detecting the operation of the clutch pedal 51, a selection signal for the forward / reverse switching lever 43 abbreviated as a linear lever, a clutch pedal switch 51s, The pedal relay input 51r and vehicle speed and other sensor signals are input to the controller C, and the solenoid outputs of the forward / reverse clutches C1 and C2 for switching and driving the forward / reverse switching mechanism 15 according to these input conditions, and the boost control thereof. The linear booster solenoid 15c, which is a proportional solenoid, and other devices can be controlled.

(Forward / backward switching control)
The forward / reverse switching control is for a reverse operation that is set separately, without using a clutch boost curve applied at the start so as not to cause a severe shock when the forward / reverse switching lever 43 is rapidly operated in the reverse direction during traveling. By applying a clutch connection boost curve, boost control is performed so that the reverse operation is smoothly performed.

  Specifically, as shown in FIG. 6, as an example of a clutch boosting curve, as a clutch boosting curve to be applied at the start, a start boosting characteristic P0 that reaches a transmission connection at a predetermined start connecting time T0, and a clutch boosting curve applied at the time of reverse operation For this purpose, a control process for switching the clutch boost curve according to the conditions is provided after the reverse boost characteristic P1 reaching the transmission connection at the reverse connection time T1 exceeding the start connection time T0 can be switched.

  As shown in the flowchart of the reverse rotation control example 1 in FIG. 7, the switching control is determined to be applicable by a first processing step (hereinafter abbreviated as “S1”) for determining that the switching lever 43 is not neutral. In the case of (i.e., forward or reverse), when the forward / reverse switching within a certain time (for example, within 500 ms) is determined (S2), the reverse boosting that reaches the transmission connection in the long reverse connection time T1 is performed. In the case of switching to the characteristic P1 and not corresponding to the forward / reverse switching determination (S2), the start boosting characteristic P0 reaching the transmission connection at the start connection time T0 is applied.

  By configuring the control process in this way, when the forward / reverse switching lever 43 is operated quickly from the neutral position, the selection-side clutch is pressure-controlled by the start boosting characteristic P0, and the switching lever 43 is operated while the vehicle is running. When the reverse side is operated rapidly, the clutch on the selection side is boosted and controlled by the reverse step-up characteristic P1 through a long reverse connection time T1, so that the vehicle can run while ensuring a smooth start by operating the switching lever when the vehicle is stopped. In the reverse operation in the middle, it is possible to shift to smooth reverse travel without causing a large travel shock.

Further, as shown in FIG. 8, another example of the clutch connection boosting curve is that the pressure increment immediately before transmission connection is boosted to a predetermined connection pressure after connection through boosting of a predetermined start connection increment H0 to be applied at the start. The start boosting characteristic P0 to be switched and the reverse boosting characteristic P2 by a small boost including no boost after connection through the boost of the reverse connection increment H2 larger than the start connection increment H0 to be applied at the time of reverse operation can be switched. In addition, by performing the same switching control as described above, the boosting range after the connection is suppressed through a large boosting of the reverse connection increment H2, so that the travel shock due to the sudden connection pressure increase at the start transmission is mitigated. Thus, the same effect as described above can be obtained.
By appropriately combining the pressure increment switching and the connection time switching described above, it is possible to further reduce the travel shock during the forward / reverse switching operation.

(Stop control)
Next, the safe stop control will be described.
As shown in the flowchart of the control processing example for the safety stop, when the pedal switch is turned off by the non-operation of the clutch pedal 51 (S11), the neutral position is determined by the neutral determination (S12) of the forward / reverse switching lever 43, as shown in FIG. If so, a control process for shutting off the power by turning on the clutch solenoid output (S13a) is provided. With this control process, the switching lever 43 can be reliably stopped by a neutral operation. Therefore, even if an attempt is made to stop the output of the switching solenoid, it is possible to avoid a dangerous situation that cannot be stopped due to a valve failure and to ensure a safe stop.

  Further, when a valve abnormality occurs, as shown in the flowchart of the abnormality handling process example in FIG. 10, when the clutch solenoid output is ON (S21) and the clutch relay input is OFF (S22), the pressure is increased within that range. By providing a control process for shutting off the power when the solenoid output is turned off (S23a), a safe stop is possible, so that a dangerous situation in which the power cannot be shut off due to disconnection of the clutch solenoid output can be avoided.

  In this case, as shown in the flowchart of the abnormality notification processing example in FIG. 11, when the clutch solenoid output is on (S31) and the clutch relay input is off (S32), an abnormality is generated by the buzzer within that range ( By providing the control processing of S33a), when the forward / reverse switching lever 43 is neutrally operated, the system abnormality can be known by the buzzer, so that it is possible to quickly cope with it.

(Pedal compatible control)
Next, the corresponding control of pedal operation will be described.
With regard to clutch connection control for returning the clutch pedal 51 from the stopped state and starting the vehicle, a clutch pedal rate limiter process for performing pressure increase control with a predetermined pressure increase pattern suitable for a smooth clutch connection operation can be applied. As shown in the flowchart of the start control example in FIG. 12, when the return operation of the clutch pedal 51 is detected (S41), if the vehicle speed is a substantial stop state (S42) in the vicinity of 0 km / h, the clutch pedal By providing a control process that applies the rate limiter process (S43a), it is possible to start smoothly without being bothered by the operation of the clutch pedal. It can respond quickly.

  As shown in a flowchart of another example of control by the clutch pedal 51, when a return operation of the clutch pedal 51 is detected (S51), when the operation speed is slow, for example, return for 500 ms is performed. By providing a control process that applies the clutch pedal rate limiter process (S53a) only when the operation amount is equal to or smaller than the predetermined amount (S52), it is possible to reliably perform start switching reflecting the operator's intention.

  As for handling during traveling, as shown in the flowchart of the control example in FIG. 14, by detecting no pressure of the forward / reverse clutch (S61), a predetermined time elapses, for example, after 5 seconds (S62). By providing a control process that enables the application of the clutch pedal rate limiter process (S63a), it is possible to avoid a sense of incongruity due to a delay in connection due to the clutch pedal rate limiter process immediately after the clutch is disengaged and When reconnecting, the clutch is smoothly connected and the feeling can be improved.

(Work implement control)
Next, the raising / lowering control of a working machine is demonstrated.
As shown in the block diagram of FIG. 15, the lifting / lowering control system of the work machine W can control the lifting / lowering solenoid output for driving the lifting / lowering mechanism 61 by the lift arm by the controller C, and the lifting / lowering speed is controlled by the proportional solenoid. It is possible to control the work implement W according to the operation of the control lever 62 and other conditions by inputting the manual operation signal of ascending / descending by the control lever sensor 62s and other related sensor signals. Configure.

  As shown in the flowchart of FIG. 16, the specific lift control is performed when a work machine descending output is detected (S71), when a predetermined time has elapsed, for example, when 10 seconds have elapsed (S72). A control process is provided for handling the valve sticking that performs a slight descent output (S73a) of the machine.

  The above-mentioned minute lowering output is lowered by a fixed stop due to a long-term stop of the spool of the hydraulic valve by repeating the lowering output of a minute time of 50 ms or the lowering output of a minute current of 0.8 A in a range where the work machine does not move. Since it is possible to prevent a situation in which the operation becomes impossible, it is possible to secure a descending operation corresponding to the next descending output.

  As for the control in the case of competing with the work implement rising output, as shown in the flowchart of the control example in FIG. 17, when there is the above-mentioned minute descent output request (S81), the work implement rise output (S82) and By providing a control process that performs a slight lowering output (S83a) within a range that does not compete, it is possible to prevent a strange behavior due to a temporary stop of the work implement ascending.

  Further, as shown in FIG. 18 which is a flowchart of a control example when the work implement is at the upper limit position, when the minute lowering output request (S91) is made, the work implement reaches the upper limit position and the work implement is being output. In this case (S92), it is possible to prevent sticking of the valve at the upper limit position by providing a control process for performing a slight downward output after interrupting the upward output (S93a).

15 Forward / backward switching mechanism 43 Forward / backward switching lever 51 Clutch pedal C1 Forward clutch C2 Reverse clutch H0 Start connection increment H2 Reverse connection increment P0 Start boost characteristic P1 Reverse boost characteristic P2 Reverse boost characteristic T0 Start connection time T1 Reverse connection time S43 Clutch pedal Rate limiter processing

Claims (3)

A multi-plate clutch (C1, C2) is provided in each of two forward and reverse traveling transmission systems that receive power in common, and one of these clutches (C1, C2) is connected to a forward / reverse switching lever (43). Of the work vehicle whose pressure is controlled by a start boosting characteristic (P0) that boosts the clutch (C1, C2) from a neutral pressure to a transmission pressure in a predetermined start connection time (T0). In the control device,
Provided is a reverse boosting characteristic (P1) for boosting with a reverse connection time (T1) longer than the start connection time (T0), and the operation of the forward / reverse switching lever (43) is in the direction opposite to the traveling direction of the work vehicle being traveled Only in this case, the travel transmission control device for a work vehicle is characterized in that the pressure-up control of the clutches (C1, C2) on the selection side is performed by the reverse boosting characteristic (P1). A multi-plate clutch (C1, C2) is provided in each of two forward and reverse traveling transmission systems that receive power in common, and one of these clutches (C1, C2) is connected to a forward / reverse switching lever (43). In accordance with the starting operation, the boosting control is performed by the starting boosting characteristic (P0) in which the clutch (C1, C2) is connected and boosted by boosting the starting connection increment (H0) by a predetermined pressure increase immediately before the transmission connection. In the traveling transmission control device of the work vehicle,
A reverse boosting characteristic (P2) for boosting the connection via boosting of the reverse connection increment (H2) exceeding the start connection increment (H0) is provided, and the operation of the work vehicle in which the operation of the forward / reverse switching lever (43) is traveling is performed. A traveling power transmission control device for a work vehicle, characterized in that the selection side clutch (C1, C2) is boosted and controlled by the reverse boosting characteristic (P2) only in the direction opposite to the direction.   As for the connection control of the clutch (C1, C2), a clutch pedal rate limiter process is provided for boosting control with a predetermined boosting pattern suitable for smooth clutch engagement operation, and the clutch pedal (51) is returned in a stopped state including a slight speed movement. 3. The travel transmission control device for a work vehicle according to claim 1, wherein the clutch pedal rate limiter process is applied only when the operation speed is lower than a predetermined speed when an operation is detected. .

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