JP2008057674A - Traveling speed changing structure of working car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a traveling speed changing structure of a working car capable of naturally changing the speed of second transmission devices even when a structure is employed for arranging the second transmission devices and second clutches in sequence at the transmission down side of first transmission devices and first clutches. <P>SOLUTION: The first transmission devices 13, 14, 15, 16 of a gear speed changing system that can change a speed variably are installed in a multistage way to which the power of an engine 1 is transmitted. The first clutches 9, 12 of a hydraulic multiple-plate system are connected in series to the first transmission devices 13, 14, 15, 16. At the transmission down side of the first transmission devices 13, 14, 15, 16 and first clutches 9, 12, the second transmission devices 44 of the gear speed changing system that can change speed variably is installed in a multistage way. The second clutches 75, 76 of the hydraulic multiple plate system are provided at the transmission down side of the second transmission device 44. A gear shift lever 106 that changes the gears of the second transmission device 44 is provided. A control means 64 is provided that disengages the firs clutches 9, 12 and the second clutches 75, 76 from the gear shift operation by the gear shift lever 106. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a first transmission to which engine power is transmitted, and a first clutch connected in series to the first transmission, and the first transmission and the first clutch are sequentially connected to the lower transmission side. The present invention relates to a traveling speed change structure for a work vehicle including a second transmission device and a second clutch.

  As a conventional technique, for example, as disclosed in Patent Document 1, a first transmission (13 to 16 in FIG. 1 of Patent Document 1) to which engine power is transmitted and the first transmission are disclosed. The first clutch (9, 12 in FIG. 1 of Patent Document 1) connected in series is provided, and the second clutch (FIG. 1 of Patent Document 1) is sequentially arranged on the lower transmission side of the first transmission and the first clutch. 6) and a second speed change device (44 and 46 in FIG. 1 of Patent Document 1), a technique related to a traveling speed change structure for a work vehicle is known.

Japanese Patent Laying-Open No. 2003-343712 (see FIG. 1)

  In the traveling speed change structure of the work vehicle disclosed in Patent Document 1, since the second transmission device is disposed on the lower transmission side of the second clutch, traveling from the second clutch (FIG. 1 in FIG. 1). The inertia weight of the transmission path to the device (53 and 54 in FIG. 1 of Patent Document 1) is heavy, and the shock when switching the second clutch is relatively large. Therefore, by arranging the second clutch on the lower transmission side of the second transmission, the inertia weight of the transmission path from the second clutch to the traveling device can be reduced, and the second clutch can be switched when switching the second clutch. It is thought that the shock can be reduced.

  Thus, when the second clutch is arranged on the lower transmission side of the second transmission to shift the second transmission, the second clutch is operated to disengage and the second shift lever is operated to change the second clutch. It is conceivable to change the speed of the transmission (for example, after the clutch pedal for operating the second clutch is stepped on and cut off with the foot, the speed change lever is manually operated to change the speed of the second transmission). Can be considered).

  However, even if only the second clutch is disengaged while the first clutch is engaged, the engine power is transmitted to the second transmission, so the first clutch side of the second transmission and the second clutch There is a large difference in the number of revolutions on the two-clutch side, and there is a risk that a shock will occur when shifting the second transmission. Specifically, for example, even when only the second clutch (for example, 75, 76 in FIG. 1) is disengaged and operated while the first clutch (for example, 9, 12 in FIG. 1) is engaged, The power of the engine is transmitted to transmission gears (for example, 45 and 46 in FIG. 1) on the first clutch side of the second transmission (for example, 44 in FIG. 1). Therefore, when an attempt is made to shift the gear-change-type second transmission (for example, 44 in FIG. 1), the first clutch side transmission gear (for example, 45 in FIG. Alternatively, it is necessary to engage the shift member (for example, 47 in FIG. 1) on the second clutch side, which has become difficult to rotate due to the disengagement operation of the second clutch. Then, the rotational speed difference between the shift member (for example, 47 in FIG. 1) and the transmission gear (for example, 45 or 46 in FIG. 1) is large, the meshing between the shift member and the transmission gear becomes poor, and the second transmission is shifted. There is a risk that the shock at the time of doing will increase.

  In the present invention, even if a configuration in which the second transmission and the second clutch are sequentially arranged on the lower transmission side of the first transmission and the first clutch is employed, the second transmission can be shifted without difficulty. An object is to realize a traveling speed change structure for a work vehicle.

[I]
(Constitution)
A first feature of the present invention resides in that the traveling speed change structure of the work vehicle is configured as follows.
The first transmission is provided with a gear transmission type first transmission that is variable in multiple stages to which engine power is transmitted, and a hydraulic multi-plate first clutch is connected in series to the first transmission. And a gear-shifting second transmission that is variable in multiple stages on the lower transmission side of the first clutch, and a hydraulic multi-plate second clutch on the lower transmission side of the second transmission. A shift lever that shifts the two-transmission device, and a control unit that operates to disengage the first clutch and the second clutch based on a shift operation of the shift lever;

(Function)
According to the first aspect of the present invention, the shift lever is provided with a shift lever that shifts the second transmission, and the control lever that operates to disengage the first clutch and the second clutch based on the shift operation of the shift lever. When shifting the speed of the second transmission by performing a speed change operation, the first clutch and the second clutch can be operated to be disengaged, the transmission of power between the engine and the second transmission, and the second transmission Transmission of power on the lower transmission side can be cut off. Therefore, it becomes difficult for the engine power to be transmitted to the second transmission, and the difference in the number of revolutions between the first clutch side and the second clutch side of the second transmission can be suppressed. The shock can be reduced.

  More specifically, for example, the second transmission device includes a shift member (for example, 47 in FIG. 1) on the second clutch side and a transmission gear (for example, 45 or 46 in FIG. 1) on the first clutch side. If the transmission of power on the lower transmission side of the second transmission is cut off by the operation of disengaging the second clutch (for example, 75 and 76 in FIG. 1), the shift member on the second clutch side ( For example, when 47) in FIG. 1 becomes difficult to rotate and the transmission of power between the engine and the second transmission is interrupted by the disengagement operation of the first clutch (for example, 9, 12 in FIG. 1), The transmission gear on the first clutch side (for example, 45 or 46 in FIG. 1) is difficult to rotate. Then, the rotational speed difference between the shift member (for example, 47 in FIG. 1) and the transmission gear (for example, 45 or 46 in FIG. 1) is reduced, and the shock when the shift member and the transmission gear are meshed can be reduced. This can reduce the shock when shifting the second transmission.

(The invention's effect)
According to the first feature of the present invention, since the shock at the time of shifting the second transmission can be reduced, the second transmission can be shifted without difficulty and the riding comfort of the work vehicle is improved. In addition, it is possible to prevent damage to equipment (for example, the shift member and the transmission gear described above) constituting the second transmission.

[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.
The control means is configured so that the first transmission is operated to a neutral position based on a shift operation of the shift lever.

(Function)
According to the second feature of the present invention, the “action” described in the preceding item [I] is provided in the same manner as the first feature of the present invention, and in addition to this, the following “action” is provided.
According to the second feature of the present invention, the control means is configured so that the first transmission is operated to the neutral position based on the shifting operation of the shifting lever, whereby the second shifting apparatus is operated by shifting the shifting lever. When shifting, the first transmission located between the engine and the second transmission can be operated to the neutral position, and the transmission of power between the engine and the second transmission can be transmitted to the first clutch. And can be shut off at two locations of the first transmission. For this reason, for example, compared with a case where transmission of power between the engine and the second transmission is cut off at one place, the power of the engine is less likely to be transmitted to the second transmission, and the second transmission is shifted. The shock can be reduced.

(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, since the shock when shifting the second transmission can be reduced, the speed change operation of the second transmission can be performed without difficulty and the riding comfort of the work vehicle is improved. Can be made.

[III]
(Constitution)
A third 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 or the second feature of the present invention.
A transmission shaft located on a transmission path between the first clutch and the shift member of the second transmission includes a brake device capable of suppressing the rotation of the transmission shaft.
The control means is configured to operate the brake device based on a shift operation of the shift lever.

(Function)
According to the third feature of the present invention, the “action” described in the preceding item [I] [II] is provided in the same manner as the first feature or the second feature of the present invention. Is provided.
For example, even if the transmission of power between the engine and the second transmission is cut off by disengaging the first clutch, the transmission is located on the transmission path between the first clutch and the shift member of the second transmission. The transmission shaft (for example, 6, 8, 11 etc. in FIG. 1), the transmission gear of the second transmission connected to the transmission shaft (for example, 45, 46 in FIG. 1), etc., are connected to the transmission shaft and the transmission gear itself. Rotates by inertia. Therefore, if the rotation due to the inertia of the transmission shaft can be suppressed, the rotation due to the inertia of the transmission gear of the second transmission mechanism connected to the transmission shaft can be suppressed, and the shift member and the transmission of the second transmission can be controlled. It is possible to suppress the gear speed difference. If it does so, the shock at the time of meshing | engaging the shift member and transmission gear of a 2nd transmission device becomes small, and the shock at the time of shifting a 2nd transmission device can be made small.

  According to the third aspect of the present invention, the transmission shaft located in the transmission path between the first clutch and the shift member of the second transmission is provided with a brake device capable of suppressing the rotation of the transmission shaft. By configuring the control means so that the brake device operates based on the speed change operation of the speed change lever, when the first clutch is disengaged, there is a gap between the first clutch and the shift member of the second speed change device. The rotation due to the inertia of the transmission shaft located in the transmission path can be suppressed by the brake device, and the rotation of the transmission gear of the second transmission mechanism connected to the transmission shaft can be suppressed. In other words, the rotation due to the inertia of the transmission gear of the second transmission can be suppressed by the brake device, the difference in the number of rotations between the shift member of the second transmission and the transmission gear can be suppressed, and the second transmission can be shifted. The shock when doing can be reduced.

(The invention's effect)
According to the third feature of the present invention, the “effect of the invention” described in the preceding paragraphs [I] and [II] is provided in the same manner as the first feature or the second feature of the present invention. “Effect of the invention” is provided.
According to the third feature of the present invention, since the shock when shifting the second transmission can be reduced, the second transmission can be shifted without difficulty and the riding comfort of the work vehicle is improved. be able to.

[IV]
(Constitution)
The fourth feature of the present invention is that the work vehicle wheel support structure of the third feature of the present invention is configured as follows.
The control means is configured so that the brake device intermittently operates based on a shift operation of the shift lever.

(Function)
According to the fourth feature of the present invention, the “action” described in the previous section [III] is provided in the same manner as the third feature of the present invention. In addition, the following “action” is provided.
For example, if the control means is configured such that the brake device is operated based on the speed change operation of the speed change lever as in the invention according to claim 3, depending on the rotational position of the transmission shaft whose rotation is suppressed by the brake device, The transmission gear on the first clutch side (for example, 45 and 46 in FIG. 1) of the second transmission connected to the transmission shaft does not mesh well with the shift member on the second clutch side (for example, 47 in FIG. 1). There is a fear.

  According to the fourth aspect of the present invention, by configuring the control means so that the brake device intermittently operates based on the shift operation of the shift lever, the rotational position where the transmission gear and the shift member of the second transmission gear mesh with each other is set in the brake device. It can be changed by intermittent operation. Therefore, the transmission gear and the shift member of the second transmission can be easily engaged with each other, and the shock when shifting the second transmission can be reduced.

  Specifically, for example, when the operation of the brake device is released from the state in which the brake device is operated on the transmission shaft, the transmission shaft and the transmission gear connected to the transmission shaft are rotated by the power that slightly flows through the transmission shaft, and this By operating the brake device again in this state, the rotational position where the transmission gear and the shift member mesh can be changed.

(The invention's effect)
According to the fourth feature of the present invention, the “effect of the invention” described in the previous section [III] is provided in the same manner as the third feature of the present invention. In addition, the following “effect of the invention” is provided. ing.
According to the fourth aspect of the present invention, since the shock at the time of shifting the second transmission can be reduced, the shifting of the second transmission can be performed without difficulty and the riding comfort of the work vehicle is improved. be able to.

[1]
FIG. 1 shows a traveling transmission system of a four-wheel drive type agricultural tractor that is an example of a work vehicle. First, the first to fourth main transmissions 13, 15, 14, and 16 corresponding to the first transmission are shown. explain.

  As shown in FIG. 1, the power of the engine 1 is transmitted to the transmission shaft 2 and transmitted to the PTO shaft 3 as described in [4] described later. A cylindrical transmission shaft 4 is externally fitted to the transmission shaft 2 so as to be relatively rotatable, and a first main transmission shaft 7 and a third main transmission shaft 8 are arranged in parallel with the transmission shafts 2, 4. A first transmission clutch 9 (corresponding to the first clutch) is provided between the third main transmission shafts 7 and 8. A second main transmission shaft 10 and a fourth main transmission shaft 11 are arranged in parallel with the transmission shafts 2 and 4, and the second transmission clutch 12 (the first clutch is connected to the first clutch) between the second and fourth main transmission shafts 10 and 11. Equivalent). The first and second transmission clutches 9 and 12 are configured by a hydraulic multi-plate type and a friction type, and are operated in a transmission state when hydraulic oil is supplied, and are operated in a cut-off state when the hydraulic oil is discharged. It is comprised so that.

  As shown in FIG. 1, a synchromesh-type first main transmission 13 is provided between the transmission shaft 2 and the first main transmission shaft 7, and between the transmission shaft 2 and the second main transmission shaft 10. A synchromesh-type second main transmission 15 is provided. A first gear 17, a second gear 18, a third gear 19, and a fourth gear 20 are fixed to the transmission shaft 2. A low-speed gear 21 and a high-speed gear 22 that are externally fitted to the first main transmission shaft 7 so as to be relatively rotatable are meshed with the first gear 17 and the third gear 19, and the shift member 23 has a first main transmission shaft by a spline structure. 7, the first main transmission 13 is configured so as to be integrally fitted and slidable. The low-speed gear 24 and the high-speed gear 25 that are externally fitted to the second main transmission shaft 10 are engaged with the second gear 18 and the fourth gear 20, and the shift member 26 has a spline structure so that the second main transmission shaft is engaged. The second main transmission 15 is configured so as to be integrally fitted and freely slidable on the main body 10.

  As shown in FIG. 1, a synchromesh-type third main transmission 14 is provided between the transmission shaft 4 and the third main transmission shaft 8, and the synchronization is provided between the transmission shaft 4 and the fourth main transmission shaft 11. A mesh type fourth main transmission 16 is provided. The low-speed gear 27 and the high-speed gear 28 are fixed to the transmission shaft 4, and the low-speed gear 29 and the high-speed gear 30 that are externally fitted to the third main transmission shaft 8 so as to be relatively rotatable are engaged with the low-speed gear 27 and the high-speed gear 28. The third main transmission 14 is configured by the shift member 31 being externally fitted to the third main transmission shaft 8 so as to be integrally rotatable and slidable by a spline structure. The low speed gear 32 and the high speed gear 33 externally fitted to the fourth main transmission shaft 11 are engaged with the low speed gear 27 and the high speed gear 28, and the shift member 34 rotates integrally with the fourth main transmission shaft 11 by a spline structure. And the 4th main transmission 16 is comprised by the outer fit so that sliding is possible.

  With the above structure, as described in [5] to be described later, the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the first and third main transmission shafts 7 and 8 (first transmission clutch 9 And the state in which the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the second and fourth main transmission shafts 10 and 11 (the transmission state of the second transmission clutch 12).

  As shown in FIG. 1, in a state where the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the first and third main transmission shafts 7 and 8 (the transmission state of the first transmission clutch 9), the transmission shaft 2. Is transmitted to the transmission shaft 4 through the first main transmission 13, the first main transmission shaft 7, the first transmission clutch 9, the third main transmission shaft 8, and the third main transmission 14. (1st speed position, 3rd speed position, 5th speed position, 7th speed position described later).

  As shown in FIG. 1, in a state where the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the second and fourth main transmission shafts 10 and 11 (the transmission state of the second transmission clutch 12), the transmission shaft 2. Is transmitted to the transmission shaft 4 through the second main transmission 15, the second main transmission shaft 10, the second transmission clutch 12, the fourth main transmission shaft 11, and the fourth main transmission 16. (2nd speed position, 4th speed position, 6th speed position, 8th speed position described later).

[2]
Next, the auxiliary transmission 44 that corresponds to the second transmission will be described.
As shown in FIG. 1, a transmission shaft 5 is arranged in parallel with the transmission shafts 2, 4, and a cylindrical transmission shaft 6 (corresponding to a transmission shaft located in the transmission path) is fitted on the transmission shaft 5 so as to be relatively rotatable. The transmission gear 43 fixed to the transmission shaft 6 is engaged with the high-speed gear 28. A synchromesh type auxiliary transmission 44 is provided between the transmission shafts 5 and 6.

  As shown in FIG. 1, a transmission gear 45 is fixed to the transmission shaft 6, and a transmission gear 46 is fitted on the transmission shaft 5 so as to be relatively rotatable, and a shift member 47 (corresponding to a shift member of the second transmission). Is externally fitted to the transmission shaft 5 by a spline structure so as to be integrally rotatable and slidable. Transmission shafts 48 and 49 arranged in parallel with the transmission shafts 5 and 6 are provided, and transmission gears 50 and 51 are fitted on the transmission shaft 48 so as to be relatively rotatable, and the transmission gear 52 is fixed to the transmission shaft 48. The transmission gears 45 and 50 are engaged, and the transmission gears 46 and 52 are engaged. Transmission gears 54 and 55 are fixed to the transmission shaft 49, the transmission gears 51 and 54 are engaged, and a shift gear 56 is externally fitted to the transmission shaft 48 by a spline structure so as to be integrally rotatable and slidable. An auxiliary speed change lever 106 (corresponding to the speed change lever) (see FIG. 2) for sliding the shift member 47 is provided, and the driver manually operates the auxiliary speed change lever 106. An ultra-low speed lever (not shown) for sliding the shift gear 56 is provided, and the driver artificially operates the ultra-low speed lever. The auxiliary transmission 44 is configured as described above.

As a result, as shown in FIG. 1, when the shift member 47 is engaged with the transmission shaft 6, the transmission shafts 5 and 6 are connected to each other, and the power of the transmission shaft 4 is converted to the high speed gear 28 and the transmission gear 43. It is transmitted to the transmission shaft 5 via the transmission shaft 6 (high speed position H of the auxiliary transmission 44).
When the shift member 47 is engaged with the transmission gear 46 in a state where the shift gear 56 is separated from the transmission gear 55 and engaged with the transmission gear 51, the power of the transmission shaft 4 is transmitted to the high-speed gear 28 and the transmission gears 43, 45, 50, It is transmitted to the transmission shaft 5 via the transmission shaft 48 and the transmission gears 52 and 46 (low speed position L of the auxiliary transmission 44).
When the shift member 47 is engaged with the transmission gear 46 and the shift gear 56 is separated from the transmission gear 51 and engaged with the transmission gear 55, the power of the transmission shaft 4 is transmitted to the high-speed gear 28 and the transmission gears 43, 45, 50, 51, transmission. It is transmitted to the transmission shaft 5 via the gears 54 and 55 and the transmission shaft 49, the shift gear 56, the transmission shaft 48, and the transmission gears 52 and 46 (very low speed position of the auxiliary transmission 44).

[3]
Next, the forward / reverse switching device 67 provided with forward and reverse clutches 75 and 76 (corresponding to the second clutch) and the transmission system from the forward / backward switching device 67 to the front wheels 77 and the rear wheels 78 will be described.
As shown in FIG. 1, a transmission shaft 66 is arranged concentrically with the transmission shaft 5, and a hydraulic clutch type forward / reverse switching device 67 is provided between the transmission shafts 5 and 66.

  As shown in FIG. 1, a cylindrical transmission shaft 68 is fitted on the transmission shaft 2 so as to be relatively rotatable, and transmission gears 69 and 70 are fixed to the transmission shaft 68, so that the transmission is fixed to the transmission shaft 5. The gear 71 is engaged with the transmission gear 69. A transmission shaft 72 is connected to the transmission shaft 66, the transmission shaft 72 is arranged concentrically with the transmission shaft 5, and a transmission gear 73 externally fitted to the transmission shaft 72 so as to be relatively rotatable is interposed via an intermediate gear 74. It meshes with the transmission gear 70. A forward clutch 75, which is a hydraulic multi-plate friction type hydraulic clutch, is provided between the transmission gear 71 and the transmission shaft 72. Between the transmission gear 73 and the transmission shaft 72, a hydraulic multi-plate type frictional hydraulic pressure is provided. A reverse clutch 76, which is a clutch, is provided, and the forward and reverse clutches 75, 76 are operated in a transmission state when hydraulic fluid is supplied, and are operated in a shut-off state when hydraulic fluid is discharged. It is configured. The forward / reverse switching device 67 is configured as described above.

  As a result, as shown in FIG. 1, when the forward clutch 75 is operated in the transmission state and the reverse clutch 76 is operated in the disconnected state, the transmission shafts 5 and 72 are connected, and the power of the transmission shaft 5 is increased. It is transmitted to the transmission shafts 72 and 66 in a forward state via the forward clutch 75. When the reverse clutch 76 is operated in the transmission state and the forward clutch 75 is operated in the disconnected state, the power of the transmission shaft 5 is transmitted to the transmission gears 71 and 69, the transmission shaft 68, the transmission gear 70, the intermediate gear 74, the transmission gear 73, and the reverse clutch. It is transmitted to the transmission shafts 72 and 66 in the reverse state via 76. A rear wheel differential mechanism 79 and a planetary reduction mechanism 80 are provided for the transmission shaft 66, and the power of the transmission shaft 66 is transmitted to the right and left rear wheels 78 via the rear wheel differential mechanism 79 and the planetary reduction mechanism 80. Communicated.

  As shown in FIG. 1, a transmission shaft 81 is arranged in parallel with the transmission shaft 66, and a transmission gear 82 fixed to the transmission shaft 66 and a transmission gear 83 fixed to the transmission shaft 81 are engaged with each other. A hydraulic clutch type front wheel transmission mechanism 85 is provided between the front wheel transmission shaft 84 and the front wheel transmission shaft 84, and a front wheel differential mechanism 86 and a planetary speed reduction mechanism 87 are provided for the front wheel transmission shaft 84. Thereby, the power of the transmission shaft 66 is transmitted to the right and left front wheels 77 via the transmission gears 82 and 83, the transmission shaft 81, the front wheel speed change mechanism 85, the front wheel differential mechanism 86 and the planetary speed reduction mechanism 87.

  As shown in FIG. 1, the front wheel transmission mechanism 85 is configured to be freely operated in a standard state where the front wheels 77 and the rear wheels 78 are driven at the same speed, and in a speed increasing state where the front wheels 77 are driven at a higher speed than the rear wheels 78. ing. In a state where the front wheels 77 are steered within the range of right and left set angles from the straight position, the front wheel speed change mechanism 85 is operated to the standard state, and the front wheels 77 are set to the right or left set angle. When the steering operation is performed to the right or to the left, the front wheel speed change mechanism 85 is operated in an accelerated state, and the small turn is smoothly performed.

[4]
Next, the transmission system to the PTO shaft 3 will be described.
As shown in FIG. 1, the transmission gear 88 is fixed to the transmission shaft 2, and the power of the transmission shaft 2 is transmitted to the hydraulic pump 90 via the transmission gear 88 and the intermediate gear 89. In this state, power is always transmitted to the hydraulic pump 90 and the hydraulic pump 90 is driven.

  As shown in FIG. 1, a transmission shaft 91 is arranged concentrically with the transmission shaft 2, and a PTO clutch 92 and a PTO transmission 93 are provided between the transmission gear 88 and the transmission shaft 91. The PTO clutch 92 is configured by a hydraulic multi-plate type and a friction type, and is configured to be operated in a transmission state when hydraulic oil is supplied and operated in a cutoff state by discharging the hydraulic oil. .

  As shown in FIG. 1, a transmission gear 94 is fixed to the PTO clutch 92, a cylindrical transmission shaft 95 is externally fitted to the transmission shaft 66 so as to be relatively rotatable, and transmission gears 96, 97, 98 are attached to the transmission shaft 95. The transmission gears 94 and 98 are engaged with each other. The transmission gears 99 and 100 are fitted on the transmission shaft 91 so as to be relatively rotatable, the transmission gears 96 and 99 are engaged, the transmission gears 97 and 100 are engaged, and the shift members 101 and 102 are transmitted by the spline structure. 91 is externally fitted to be integrally rotatable and slidable. A transmission gear 103 is fixed to the transmission shaft 66, a transmission gear 104 is externally fitted to the transmission shaft 91 so as to be relatively rotatable, and the transmission gears 103 and 104 are engaged. The PTO transmission 93 is configured as described above.

  Thus, as shown in FIG. 1, when the shift member 101 is engaged with the transmission gear 99, the power of the PTO clutch 92 is transmitted in a low speed state via the transmission gears 94, 98, the transmission shaft 95, and the transmission gears 96, 99. It is transmitted to the transmission shaft 91 and the PTO shaft 3. When the shift member 102 is engaged with the transmission gear 100, the power of the PTO clutch 92 is transmitted to the transmission shaft 91 and the PTO shaft 3 at a medium speed through the transmission gears 94, 98, the transmission shaft 95, and the transmission gears 97, 100. Is done. When the shift member 102 is engaged with the transmission gear 94, the PTO clutch 92 and the transmission shaft 91 are connected, and the power of the PTO clutch 92 is transmitted to the transmission shaft 91 and the PTO shaft 3 in a high speed state. When the shift member 101 is engaged with the transmission gear 104, the power of the transmission shaft 66 is transmitted to the transmission shaft 91 and the PTO shaft 3 via the transmission gears 103 and 104.

[5]
Next, the operation structure of the first main transmission 13 and the third main transmission 14, the second main transmission 15 and the fourth main transmission 16 will be described.
As shown in FIGS. 1 and 2, in the first main transmission 13, a double-acting hydraulic cylinder type actuator 35 that slides a shift member 23, and a control valve 39 that supplies and discharges hydraulic oil to and from the actuator 35 are provided. The third main transmission 14 includes a double-acting hydraulic cylinder type actuator 36 that slides the shift member 31, and a control valve 40 that supplies and discharges hydraulic oil to and from the actuator 36. The actuator 35 is configured to be operable to a low speed position L where the shift member 23 meshes with the low speed gear 21, and a high speed position H where the shift member 23 meshes with the high speed gear 22 and a neutral position N. The actuator 36 includes the shift member 31. The low-speed position L that meshes with the low-speed gear 29 and the high-speed position H that the shift member 31 meshes with the high-speed gear 30 are configured to be operable.

  As shown in FIGS. 1 and 2, in the second main transmission 15, a double-acting hydraulic cylinder type actuator 37 that slides the shift member 26, and a control valve 41 that supplies and discharges hydraulic fluid to the actuator 37 are provided. The fourth main transmission 16 includes a double-acting hydraulic cylinder type actuator 38 that slides the shift member 34, and a control valve 42 that supplies and discharges hydraulic oil to and from the actuator 38. The actuator 37 is configured to be operable at a low speed position L where the shift member 26 meshes with the low speed gear 24, a high speed position H where the shift member 26 meshes with the high speed gear 25, and a neutral position N. The actuator 38 includes the shift member 34. The low-speed position L that meshes with the low-speed gear 32 and the high-speed position H that the shift member 34 meshes with the high-speed gear 33 are configured to be freely movable.

  As shown in FIG. 2, an electromagnetic proportional pressure reducing valve type control valve 59 for supplying and discharging hydraulic oil to the forward clutch 75, an electromagnetic proportional pressure reducing valve type control valve 60 for supplying and discharging hydraulic oil to the reverse clutch 76, An electromagnetic proportional pressure reducing valve type control valve 61 for supplying and discharging hydraulic oil to the first transmission clutch 9 and an electromagnetic proportional pressure reducing valve type control valve 62 for supplying and discharging hydraulic oil to the second transmission clutch 12 are provided. .

  As shown in FIGS. 1 and 8 with the above structure, the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the first and third main transmission shafts 7 and 8 (the transmission of the first transmission clutch 9). State), the low speed position L of the shift member 31 is the first speed position, the low speed position L of the shift member 31 is the high speed position H of the shift member 23, and the high speed position of the shift member 31. At H, the low speed position L of the shift member 23 is the fifth speed position, and at the high speed position H of the shift member 31, the high speed position H of the shift member 23 is the seventh speed position. In the first and third speed positions described above, the second transmission clutch 12 is operated to be disconnected, and the shift member 26 is in the neutral position N and the shift member 34 is in the low speed position L. At the 5th and 7th speed positions, the second transmission clutch 12 is operated in the disconnected state, the shift member 26 is in the neutral position N, and the shift member 34 is in the high speed position H.

  As shown in FIGS. 1 and 8, in a state where the power of the transmission shaft 2 is transmitted to the transmission shaft 4 via the second and fourth main transmission shafts 10 and 11 (the transmission state of the second transmission clutch 12), At the low speed position L of the shift member 34, the low speed position L of the shift member 26 is at the second speed position, at the low speed position L of the shift member 34, the high speed position H of the shift member 26 is at the fourth speed position, and at the high speed position H of the shift member 34. 26, the low speed position L of the shift member 26 is the 6th speed position, and the high speed position H of the shift member 34 is the 8th speed position. In the above-described second and fourth speed positions, the first transmission clutch 9 is operated to be disconnected, and the shift member 23 is in the neutral position N and the shift member 31 is in the low speed position L. At the 6th and 8th speed positions, the first transmission clutch 9 is operated in the disconnected state, the shift member 23 is in the neutral position N and the shift member 31 is in the high speed position H.

  As shown in FIG. 2, a main transmission lever 63 and a forward / reverse lever 57 that can be operated at the 1st to 8th speed positions are provided, and an operation switch 65 that is biased toward the protruding side is provided at a grip portion of the main transmission lever 63. The operation positions of the main transmission lever 63, the forward / reverse lever 57, and the operation switch 65 are input to the control device 64 (corresponding to control means). A seven-segment display unit 53 is provided, and the operation position of the main transmission lever 63 or the transmission positions (first speed position) of the first and third main transmissions 13 and 14 and the second and fourth main transmissions 15 and 16 are provided. -8th position) (see FIG. 8) is displayed on the display unit 53.

  As shown in FIG. 2, as described in [6], [7], and [8], which will be described later, the control device 64 operates the operation positions of the main transmission lever 63 and the forward / reverse lever 57 and the operation switch 65 (first position). And the second transmission mode), the control valves 39 to 42 and 59 to 62 are operated to operate the actuators 35 to 38, and the forward and reverse clutches 75 and 76, the first and second transmission clutches 9 and 12 are operated. To power and shut off. When the forward / reverse lever 57 is operated to the forward position F, the forward clutch 75 is operated to the transmission state and the reverse clutch 76 is operated to be disconnected, and when the forward / reverse lever 57 is operated to the reverse position R, the reverse clutch 76 is transmitted. Is operated to move the forward clutch 75 to the disengaged state.

  A clutch pedal (not shown) is provided for the forward and reverse clutches 75, 76, which can be stepped on artificially, and the operation position of the clutch pedal is input to the control device 64. Accordingly, when the forward / reverse lever 57 is operated to the forward position F (the forward clutch 75 is operated to the transmission state and the reverse clutch 76 is operated to be disconnected), the forward clutch is operated when the clutch pedal is depressed. When 75 is operated in the disconnected state and the clutch pedal is returned, the forward clutch 75 is operated in the transmission state. In a state where the forward / reverse lever 57 is operated to the reverse position R (a state where the reverse clutch 76 is operated in the transmission state and the forward clutch 75 is operated in the disengaged state), when the clutch pedal is depressed, the reverse clutch 76 is disengaged. When the clutch pedal is operated to return to the state, the reverse clutch 76 is operated to the transmission state.

[6]
In this agricultural tractor, the first shift mode and the second shift mode are provided in the control device 64, and the driver selects the first shift mode and the second shift mode with the operation switch 65. When the main transmission lever 63 is operated without pressing the operation switch 65, the first transmission mode is selected, and when the operation switch 65 is operated and the main transmission lever 63 is operated, the second transmission mode is selected.

Next, the first half of the first speed change mode will be described with reference to FIGS.
In a state before the main transmission lever 63 and the operation switch 65 are operated, the current first and third main transmission devices 13 and 14 and the second and fourth main transmission devices 15 and 16 are in the shift positions (first speed position to 8th position). (Speed position) is displayed on the display unit 53 (step S1). In this state, if the main transmission lever 63 is operated (step S3) without pressing the operation switch 65 (step S2), the first transmission mode is set.

  As will be described later, in the first speed change mode, when the main speed change lever 63 is operated from one operation position to another operation position, the operation before the main speed change lever 63 is operated so as to follow the operation of the main speed change lever 63. The first and third main transmissions 13 and 14 and the second and fourth main transmissions 15 and 16 are operated step by step from the shift position corresponding to the position (1st speed position to 8th speed position). The lever 63 is operated so as to reach a speed change position (first speed position to eighth speed position) corresponding to an operation position after the operation of the lever 63 (operation position where the main speed change lever 63 is stopped).

  For example, when the main transmission lever 63 is operated from the first speed position to the fifth speed position, the first and third main transmission apparatuses 13 and 14 and the second and fourth main transmission apparatuses 15 and 16 change from the first speed position to the second speed position. , The operation from the 2nd speed position to the 3rd speed position is performed, the operation from the 3rd speed position to the 4th speed position is performed, and the operation from the 4th speed position to the 5th speed position is performed. For example, when the main transmission lever 63 is operated from the sixth speed position to the third speed position, the first and third main transmission apparatuses 13 and 14 and the second and fourth main transmission apparatuses 15 and 16 change from the sixth speed position to the fifth speed position. Is operated, the operation from the fifth speed position to the fourth speed position is performed, and the operation from the fourth speed position to the third speed position is performed.

  For example, the main speed change lever 63 is operated to the first speed position (the shift member 23 is at the low speed position L, the shift member 26 is at the neutral position N, the shift members 31 and 34 are at the low speed position L, the forward clutch 75 (reverse clutch 76 ) And the first transmission clutch 9 is in the transmission state at the operating pressure P1, and the second transmission clutch 12 is in the cutoff state at the operating pressure P0), for example, the main transmission lever 63 starts to operate to the high speed side (step S3) Assume that the operation is stopped at the fifth speed position (the state where the main transmission lever 63 is stopped at the fifth speed position) (step S19), the fifth speed position at which the main transmission lever 63 is stopped is set as the target transmission position (step S19). Step S20). In this case, as will be described later, when the main transmission lever 63 starts to be operated from the first speed position, the first and third main transmissions 13 and 14, the second and the fourth main transmission devices 13 and 14 follow the operation of the main transmission lever 63. The main transmissions 15 and 16 are started to operate.

  As described above, when the main transmission lever 63 is operated from the state where the main transmission lever 63 is operated to the first speed position (step S3) (time point T11), the shift member 26 is moved from the neutral position N to the low speed position L. Operated (steps S4 and S5) (from time T11 to time T12). Thus, the shift members 23 and 31 are in the first speed position, and the shift members 26 and 34 are in the second speed position. In this case, the shift member 34 is not operated to the high speed position H but remains in the low speed position L (passes through step S6) (see FIG. 8).

  When the shift member 26 is operated to the low speed position L (second speed position) (step S5) (time point T12), the forward clutch 75 (reverse clutch 76) is intermediate between the operating pressures P2 (operating pressures P0 and P1). The pressure is quickly reduced to a semi-transmission state (step S7) (time point T12) (see solid line A3). At substantially the same time, the second transmission clutch 12 is boosted relatively quickly from the operating pressure P0 and operated to the transmission state (from time T12 to time T13) (see dotted line A2), while the first transmission clutch 9 is operating pressure P1. Then, the pressure is reduced relatively quickly and the shut-off state is operated (step S8) (from time T12 to time T13) (see the alternate long and short dash line A1).

  As a result, as shown in FIG. 1, the power when the shift members 23 and 31 are in the first speed position is transmitted to the transmission shaft 4 and at the same time the power when the shift members 26 and 34 are in the second speed position. Is transmitted to the transmission shaft 4 and merges, and even if a torque fluctuation occurs in the double transmission state, the forward clutch 75 (reverse clutch 76) in the semi-transmission state slips to some extent. Torque fluctuations are absorbed and power with little torque fluctuations is transmitted to the front wheels 77 and the rear wheels 78.

When the second transmission clutch 12 is operated to the transmission state at the operating pressure P1 and the first transmission clutch 9 is operated to the disconnected state at the operation pressure P0 (time point T13), the shift member 23 is operated to the neutral position N ( Step S9) (from time T13 to time T14). In this case, the shift member 31 is not operated to the high speed position H but remains in the low speed position L (passes through step S10) (see FIG. 8). When the shift member 23 is operated to the neutral position N (time T14), the forward clutch 75 (reverse clutch 76) is gradually increased from the operating pressure P2, reaches the operating pressure P1, and is operated to the transmission state (step S11). (Time T14 to Time T15).
As described above, the operation from the first-speed position to the second-speed position is completed, and the first and third main transmissions 13, 14 and the second and fourth main transmissions 15, 16 after the operation are shifted. The position (second speed position) is displayed on the display unit 53 (step S18).

[7]
Next, the second half of the first shift mode will be described with reference to FIG.
When the operation from the first speed position to the second speed position as described in [6] is completed, the process proceeds from step S22, S4 to step S12, and the shift member 23 is in the state where the shift members 26, 34 are in the second speed position. , 31 are operated to the third speed position (step S12). In this case, the shift member 31 is not operated to the high speed position H but remains in the low speed position L (passed through step S13) (see FIG. 8). The forward clutch 75 (reverse clutch 76) is quickly depressurized to the operating pressure P2 (intermediate between the operating pressures P0 and P1) and is operated to a half transmission state (step S14). The second transmission clutch 12 is depressurized relatively quickly from the operating pressure P1 and operated to the disconnected state while the pressure is increased from the operating pressure P0 relatively quickly and is operated to the transmission state (step S15).

  As a result, as shown in FIG. 1, the power when the shift members 26 and 34 are in the second speed position is transmitted to the transmission shaft 4, and at the same time, the power when the shift members 23 and 31 are in the third speed position. Is transmitted to the transmission shaft 4 and merges, and even if a torque fluctuation occurs in the double transmission state, the forward clutch 75 (reverse clutch 76) in the semi-transmission state slips to some extent. Torque fluctuations are absorbed and power with little torque fluctuations is transmitted to the front wheels 77 and the rear wheels 78.

When the first transmission clutch 9 is operated to the transmission state at the operating pressure P1, and the second transmission clutch 12 is operated to the disconnected state at the operation pressure P0, the shift member 26 is operated to the neutral position N (step S16). In this case, the shift member 34 is not operated to the high speed position H but remains in the low speed position L (passes through step S17) (see FIG. 8). When the shift member 26 is operated to the neutral position N, the forward clutch 75 (reverse clutch 76) is gradually increased from the operating pressure P2, reaches the operating pressure P1, and is operated to the transmission state (step S11).
As described above, the operation from the second speed position to the third speed position is completed, and the first and third main transmissions 13, 14 and the second and fourth main transmissions 15, 16 after the operation are shifted. The position (third speed position) is displayed on the display unit 53 (step S18).

  When the operation from the 2nd gear position to the 3rd gear position is completed as described above, the shift members 23 and 31 are then in the 3rd gear position state, and the shift members 26 and 34 are in the 4th gear position and the 4th gear position is shifted to 4 The operation to the high speed position is performed based on the previous item [6] and steps S4 to S11 (in this case, the shift members 34 and 31 are not operated to the high speed position H but remain in the low speed position L (step S6, S6). (S10 is passed) (see FIG. 8).

Next, the operation from the fourth speed position to the fifth speed position with the shift members 26 and 34 in the fourth speed position and the shift members 23 and 31 in the fifth speed position is described in [7] and steps S4 and S12- (In this case, in step S13, the shift member 31 is operated from the low speed position L to the high speed position H. In step S17, the shift member 34 is changed from the low speed position L to the high speed position H.) (See FIG. 8).
As described above, the display of the shift positions of the first and third main transmissions 13 and 14 and the second and fourth main transmissions 15 and 16 after the operation is repeated step by step, thereby changing the main shift. When the lever 63 reaches the target shift position (5-th gear position) where it has stopped (step S22), the operation ends.

[8]
Next, the second speed change mode will be described based on FIGS.
In a state before the main transmission lever 63 and the operation switch 65 are operated, the current first and third main transmission devices 13 and 14 and the second and fourth main transmission devices 15 and 16 are in the shift positions (first speed position to 8th position). (Speed position) is displayed on the display unit 53 (step S1). In this state, when the operation switch 65 is pressed (step S2), the second speed change mode is set.

  As described later, in the second speed change mode, when the main speed change lever 63 is operated from one operation position to another operation position, the speed change position (first speed position to 8th speed position) corresponding to the operation position before the main speed change lever 63 is operated. Speed position) to the speed change position (first speed position to eighth speed position) corresponding to the operation position after the operation of the main speed change lever 63 (the operation position where the main speed change lever 63 is stopped). In addition, the first and third main transmissions 13, 14 and the second and fourth main transmissions 15, 16 are operated at once (for example, from the state where the main transmission lever 63 is operated to the first speed position, the operation switch 65 is operated. When the main transmission lever 63 is operated to the 4th speed position by pressing the first and third main transmission apparatuses 13 and 14 and the second and fourth main transmission apparatuses 15 and 16 pass through the 2nd and 3rd speed positions. Without moving from the 1st gear position to the 4th gear position It is).

  For example, the main speed change lever 63 is operated to the first speed position (the shift member 23 is at the low speed position L, the shift member 26 is at the neutral position N, the shift members 31 and 34 are at the low speed position L, the forward clutch 75 (reverse clutch 76 ) And the first transmission clutch 9 in the transmission state at the operating pressure P1, and the second transmission clutch 12 in the cutoff state at the operating pressure P0), the operation switch 65 is pressed and operated (the operation switch 65 is pressed and operated). (Step S2) and the second shift mode is set.

  As a result, the forward clutch 75 (reverse clutch 76) is quickly reduced to the operating pressure P0 and is operated to be disconnected (step S31) (time T21) (see the solid line A3), and the main transmission lever 63 is moved from the first speed position. As the operation is continued, the current operation position of the main transmission lever 63 is displayed on the display unit 53 (steps S32 and S33), and the operation position where the main transmission lever 63 is stopped (the main transmission lever 63 is The stopped state) is set as the target shift position (step S34). Since the operation position at which the main shift lever 63 is stopped is displayed on the display unit 53, the target shift position can be confirmed by viewing the display unit 53.

  When the target shift position is set as described above (step S34), the first and third main transmissions 13, 14 (shift members 23, 31), the second and fourth main transmissions 15, 16 (shift member) 26, 34) are operated at once to the target shift position (step S35) (see FIG. 8), and the first and second transmission clutches 9 and 12 correspond to the target shift position (see FIG. 8). The shut-off state is operated (step S36).

For example, when the main transmission lever 63 is operated from the 1st speed position to the 4th speed position and the 4th speed position is set as the target transmission position (step S34), the shift member 23 is operated from the low speed position L to the neutral position N. The shift member 26 is operated from the neutral position N to the high speed position H (from time T22 to time T23) (the shift members 31 and 34 are held at the low speed position L). At the same time, the first transmission clutch 9 is quickly reduced to the operating pressure P0 and operated in a disconnected state (see alternate long and short dash line A1) (time point T22), and the second transmission clutch 12 is immediately increased to the operating pressure P1. The transmission state is operated (see dotted line A2) (time point T22).
Next, the forward clutch 75 (reverse clutch 76) is gradually increased from the operating pressure P0 to reach the operating pressure P1 (see the solid line A3), and the forward clutch 75 (reverse clutch 76) is operated to the transmission state (step S37). (Time T24) (see solid line A3). The operation is finished as described above.

  For example, when the main transmission lever 63 is operated from the second speed position to the first speed position, the shift members 23 and 26 (the shift members 31 and 34 are held at the low speed position L) are operated as shown in FIG. 4, the state of the first and second transmission clutches 9 and 12 is reversed, the first transmission clutch 9 is operated from the disconnected state to the transmitted state, and the second transmission clutch 12 is disconnected from the transmitted state. As shown by the solid line A3 in FIG. 4, the forward clutch 75 (reverse clutch 76) is depressurized and boosted.

  For example, when the main transmission lever 63 is operated from the first speed position to the third speed position, the shift member 23 is operated as shown in FIG. 8, but the shift member 26 remains in the neutral position N (shift members 31, 34). Is held at the low speed position L), the first transmission clutch 9 is held in the transmission state, the second transmission clutch 12 is held in the disconnected state, and the forward clutch 75 (reverse drive as shown by the solid line A3 in FIG. 4). The clutch 76) is depressurized and boosted.

  For example, when the main speed change lever 63 is operated from the second speed position to the fourth speed position, the shift member 26 is operated as shown in FIG. 8, but the shift member 23 remains in the neutral position N (shift members 31, 34). Is held at the low speed position L), the first transmission clutch 9 is held in the disconnected state, the second transmission clutch 12 is held in the transmission state, and the forward clutch 75 (reverse drive as shown by the solid line A3 in FIG. 4). The clutch 76) is depressurized and boosted.

  In the first speed change mode described in [6] and [7] above, the main speed change lever 63 is operated from one operation position to another operation position so as to follow the operation of the main speed change lever 63 (the main speed change lever 63 is It is assumed that the first and third main transmissions 13 and 14 and the second and fourth main transmissions 15 and 16 are operated one step at a time (so as to aim at the stopped target shift position) (steps S4 to S4 in FIG. 6). S22). When the operation switch 65 is pressed in this state (step S21), the process proceeds to step S34 in FIG. 7, and the first and second main transmissions 13, 14 (shift members 23, 31), the second and fourth main transmissions are performed. The transmissions 15 and 16 (shift members 26 and 34) are operated at once to the target shift position (steps S35 to S37).

[9]
Next, the structure of the brake device 110 will be described with reference to FIGS. 9 and 10.
9 and 10 show a structure of the brake device 110 capable of suppressing the rotation of the transmission shaft 6. As shown in FIGS. 9 and 10, the agricultural tractor brake device 110 is configured to be able to suppress rotation of the transmission shaft 6 by a brake drum 111, a brake arm 112, a brake cylinder 113, a brake lining 116, and the like. Has been.

  A transmission shaft 6 in which the transmission shaft 5 is fitted is rotatably supported by a transmission case 109 via a bearing 114, and a spline groove is formed on the outer peripheral portion of the transmission shaft 6. A brake drum 111 is fitted in the spline groove of the transmission shaft 6 so as to be rotatable together with the transmission shaft 6.

  On the lower side of the brake drum 111, a brake arm 112 is swingably supported around an axis P3 of the swing shaft 115 at the upper end thereof. The portion of the brake arm 112 that contacts the brake drum 111 is formed in an arc shape along the arc of the outer periphery of the brake arm 112, and the brake lining 116 can be attached to and detached from the arc-shaped portion. It is attached. A long hole 112a is formed in the lower end portion of the brake arm 112, and a distal end portion of a cylinder rod 113a of a brake cylinder 113 described later is linked to the long hole 112a.

  The brake cylinder 113 is configured as a single-rod hydraulic single-acting cylinder with a built-in spring 113b that biases the cylinder rod 113a in an extended state, and supplies hydraulic oil from a cylinder port 113c located on the cylinder rod 113a side. Then, the brake cylinder 113 is shortened, and when the hydraulic oil is discharged from the cylinder port 113c, the brake cylinder 113 is extended by the urging force of the spring 113b.

  The brake cylinder 113 is supported by a pin 118 positioned to the left of the support shaft 117 in a state where the end of the cylinder tube 113d side is rotatably supported by the transmission case 109 around the axis P4 by the support shaft 117. The direction is positioned and the mission case 109 is fixed. That is, the brake cylinder 113 is fixed to the transmission case 109 so as not to swing by the support shaft 117 and the pin 118. One end of a connecting pin 119 is attached to the tip of the cylinder rod 113a of the brake cylinder 113 so as to be rotatable around an axis P5 in the expansion / contraction direction of the brake cylinder 113, and the other end of the connecting pin 119 is the brake arm 112 described above. It is loosely fitted in a long hole 112a provided at the lower end of the.

  A hydraulic joint 120 piped to the solenoid valve 105 is attached to the lower left part of the mission case 109, and a steel pipe pipe 121 extends from the hydraulic joint 120 along the inner surface side of the mission case 109. Then, it is connected to a cylinder port 113 c of the brake cylinder 113 via a hydraulic joint 122.

  By configuring the brake device 110 as described above, when hydraulic oil is supplied from the solenoid valve 105 to the brake cylinder 113 via the pipe pipe 121, the brake cylinder 113 is shortened and the brake that is loosely fitted to the cylinder rod 113a. The lower end of the arm 112 is pulled toward the brake cylinder 113 side. Then, the brake arm 112 swings around the axis P3 of the swing shaft 115, the brake lining 116 contacts the outer peripheral surface of the brake drum 111, and the tensile force of the brake cylinder 113 is applied to the swing shaft 115. Using the axis P3 as a fulcrum, it acts as a frictional force on the contact surface between the brake lining 116 and the brake drum 111. This frictional force can suppress the rotation of the transmission shaft 6 that rotates integrally with the brake drum 111.

  On the other hand, when the hydraulic oil supplied to the brake cylinder 113 is discharged by switching the solenoid valve 105, the brake cylinder 113 is extended by the urging force of the spring 113b, and the lower end portion of the brake arm 112 loosely fitted to the cylinder rod 113a is connected to the brake cylinder 113. Push to the opposite side to the 113 side. Then, the brake arm 112 swings around the swing axis P3, the brake lining 116 moves away from the outer peripheral surface of the brake drum 111, and the brake device 110 returns to the released state.

  Thus, the brake cylinder 113 is fixed to the transmission case 109 so as not to swing, and the brake lining 116 is fixed to the brake drum 111 by expansion and contraction of the brake cylinder 113 and interchange of the long hole 112a provided in the lower end portion of the brake arm 112. By adopting a configuration for contacting the cylinder cylinder 113, the position of the cylinder port 113c of the brake cylinder 113 can be fixed. Therefore, it is possible to hydraulically connect not with a hydraulic hose (not shown) but with a pipe pipe 121 made of steel pipe, and there is no need to worry about an increase in manufacturing cost and aged deterioration of the hydraulic hose by adopting the hydraulic hose, The cost of the hydraulic piping can be reduced, and the reliability of the hydraulic piping can be improved.

[10]
Next, the first half of the clutch disengagement control will be described with reference to FIGS.
As shown in FIG. 2, the agricultural tractor control device 64 includes an electromagnetic proportional pressure reducing valve type electromagnetic valve 105 for supplying and discharging hydraulic oil to and from the brake cylinder 113, and current is supplied from the control device 64 to the electromagnetic valve 105. The brake cylinder 113 can be shortened by supplying, and the brake cylinder 113 can be extended by stopping the supply of current from the control device 64 to the solenoid valve 105.

  The control section (not shown) of the agricultural tractor includes a sub-transmission lever 106 (corresponding to a transmission lever) that shifts the sub-transmission device 44 corresponding to the second transmission device. When the speed change operation is performed, the shift member 47 is engaged with the transmission gear 45, and when the speed change operation of the auxiliary transmission lever 106 is performed to the low speed position L, the shift member 47 is engaged with the transmission gear 46. The grip portion 106a of the auxiliary transmission lever 106 is provided with a clutch button 107 that can be pushed with a thumb by holding the auxiliary transmission lever 106 with one hand and biased to the protruding side. The clutch button 107 is connected to the control device 64, and is configured to perform clutch disconnection control to be described later when the clutch button 107 is pressed.

  FIG. 11 shows a control flow of clutch disengagement control according to the present invention. As shown in FIG. 11, when the clutch button 107 provided on the auxiliary transmission lever 106 is pressed (step S41), the control valve 59 for supplying and discharging hydraulic oil to and from the forward and reverse clutches 75 and 76 corresponding to the second clutch. A second clutch disengagement command is issued to the controller 60 from the control device 64 (step S42), and the forward and reverse clutches 75 and 76 are disengaged and operated. Next, a first clutch disengagement command is issued from the control device 64 to the control valves 61 and 62 for supplying and discharging hydraulic oil to and from the first and second transmission clutches 9 and 12 corresponding to the first clutch (step S43). The first and second transmission clutches 9 and 12 are turned off and operated.

  Next, the control device 64 to the first transmission device are connected to the control valves 39 and 41 for supplying and discharging hydraulic oil to and from the actuators 35 and 37 for operating the first and second main transmission devices 13 and 15 corresponding to the first transmission device. A neutral command is issued (step S44), and the first and second main transmissions 13 and 15 are operated to the neutral position N. And it transfers to the brake device intermittent operation control (step S45) mentioned later for operating the brake cylinder 113 intermittently.

  In this way, when the clutch button 107 is pressed (step S41), the forward and reverse clutches 75 and 76, the first and second transmission clutches 9 and 12 are all turned off, and the transmission of power before and after each clutch is cut off. In addition, the first and second main transmissions 13 and 15 are operated to the neutral position N so that the transmission of power in the first and second main transmissions 13 and 15 is interrupted (step). S42-44).

[11]
Next, the brake device intermittent operation control will be described with reference to FIGS.
FIG. 12 shows a control flow of the brake device intermittent operation control. As shown in FIG. 12, when the clutch button 107 is pressed (steps S41 to S44) and the control shifts to the brake cylinder intermittent operation control (step S45), a current is supplied to the electromagnetic valve 105 that supplies hydraulic oil to the brake cylinder 113. Then, the brake cylinder 113 is shortened to operate the brake device 110 (step S51). The time for operating the brake device 110 is set in the timer 1 (first set time t1), and the brake device 110 is operated for the first set time t1 set in the timer 1 (steps S52, NO, S53, YES)

  When the first set time t1 set in the timer 1 has elapsed (YES in step S52), the supply of current to the electromagnetic valve 105 is cut off, the brake cylinder 113 is extended, and the brake device 110 is released (step S54). The time for releasing the brake device 110 is set in the timer 2 (second set time t2) (steps S55, NO, S56, YES), and when the second set time t2 set in the timer 2 elapses (step S55). (YES), current is supplied again to the solenoid valve 105 (step S57), the brake cylinder 113 is shortened, and the brake device 110 is operated. The time for operating the brake device 110 is set in the timer 3 (second set time t2) (steps S58, NO, S59, YES), and the brake device 110 is operated for the second set time t2 set in the timer 3. Operate.

  When the second set time t2 set in the timer 3 has elapsed (step S58, YES), the supply of current to the solenoid valve 105 is shut off again (step S54), and the brake cylinder 113 is extended to release the brake device 110. . Thereafter, the operation of the brake device 110 and the release operation are repeated (steps S54 to S58, YES).

  FIG. 13 shows a time chart of ON and OFF of the solenoid valve 105 in the brake device intermittent operation control. As shown in FIG. 13, immediately after the clutch button 107 is pressed, the rotation of the transmission shaft 6 is suppressed by supplying the current to the electromagnetic valve 105 and operating the brake device 110 for the first set time t1. The brake device 110 can be intermittently operated by turning ON or OFF the current supply to the electromagnetic valve 105 at every second set time t2. The second set time t2 is set to be shorter than the first set time t1, and is configured so that the frictional force of the brake device 110 can be applied for a long time immediately after the clutch button 107 is pressed.

  As shown in FIG. 12, when the pressing operation of the clutch button 107 is released within the time set in the timer 1 or the timer 3 (steps S53, NO, S59, NO), the current to the solenoid valve 105 is immediately The supply is cut off, the brake device 110 is released, and the brake device intermittent operation control is terminated (step S60), and the pressing operation of the clutch button 107 is released within the time set in the timer 2 Is configured to end the brake device intermittent operation control (step S56, NO).

[12]
Next, the second half of the clutch disengagement control will be described with reference to FIG.
As shown in FIG. 11, when the pushing operation of the clutch button 107 is released and the brake device intermittent operation control is finished, the control valve 59 for supplying / discharging hydraulic oil to and from the forward and reverse clutches 75 and 76 corresponding to the second clutch. 60, a second clutch engagement command is issued from the control device 64 (step S46), and the forward and reverse clutches 75 and 76 are put into a transmission state and operated. Next, a first clutch engagement command is issued from the control device 64 to the control valves 61 and 62 for supplying and discharging hydraulic oil to and from the first and second transmission clutches 9 and 12 corresponding to the first clutch (step S47). The first and second transmission clutches 9 and 12 are put into a transmission state and operated. Further, the first transmission returns from the control device 64 to the control valves 39 and 41 for supplying and discharging hydraulic oil to the actuators 35 and 37 for operating the first and second main transmissions 13 and 15 corresponding to the first transmission. A command is issued (step S48), and the first and second main transmissions 13 and 15 are operated to the shift position (L or H) before the neutral position N is operated.

  As described above, when the operation of pressing the clutch button 107 is released, all of the forward and reverse clutches 75 and 76, the first and second transmission clutches 9 and 12 are engaged, and the first and second main shifts are performed. The control device 64 is configured to return to the state before the clutch button 107 is pressed by being operated to the shift position (L or H) before the devices 13 and 15 are operated to the neutral position N (steps S46 to S46). 48).

  In this agricultural tractor, the control device 64 is configured to perform the above-described clutch disengagement control and brake device intermittent operation control based on the gear shifting operation of the ultra-low speed lever that shifts the auxiliary transmission device 44. Specifically, a second clutch button (not shown) is provided in a grip portion (not shown) of the ultra-low speed lever, and the shift member 56 of the sub-transmission device 44 is transmitted to the transmission gear 51 by shifting the ultra-low speed lever. Alternatively, the control device 64 is configured to perform clutch disengagement control and brake device intermittent operation control when the second clutch button is pressed when meshing with the transmission gear 55.

  Thus, the shift member of the sub-transmission device 44 is configured by configuring the control device 64 so as to perform the clutch disengagement control and the brake device intermittent operation control when shifting not only the sub-transmission lever 106 but also the ultra-low speed lever. The shock at the time of meshing 56 with the transmission gear 51 or the transmission gear 55 can be reduced, and the shift of the auxiliary transmission 44 by the ultra-low speed lever can be performed without difficulty.

[First Alternative Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention], two systems of first and third main transmissions 13 and 14 corresponding to the first transmission and second and fourth main transmissions 15 and 16 are provided. The first transmission is configured to be capable of shifting to eight speeds. However, in the case of a gear transmission-type first transmission that is variable to a plurality of speeds, the number of shift speeds and the first to fourth speeds The combination of the main transmissions 13 to 16 may be different. For example, the first transmission may be configured by only one of the first and third main transmissions 13 and 14 or the second and fourth main transmissions 15 and 16. The first transmission may be configured by a combination of 13 and the second main transmission 15.

  In the above-mentioned [Best Mode for Carrying Out the Invention], between the first and third main transmissions 13 and 14 corresponding to the first transmission and between the second and fourth main transmissions 15 and 16. In this example, the first and second transmission clutches 9 and 12 corresponding to the first clutch are connected in series between the first clutch and the first clutch. You may employ | adopt the structure which connects a 1st clutch in a different position with respect to a 1st transmission. For example, the first and second transmission clutches 9 and 12 may be connected to the transmission upstream side of the first and second main transmissions 13 and 15, and the transmission downstream side of the third and fourth main transmissions 14 and 16. The first and second transmission clutches 9 and 12 may be connected to each other.

[Second Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] and [First Different Embodiment of the Invention], a clutch button 107 is provided on the auxiliary transmission lever 106 corresponding to the transmission lever, and the clutch button 107 is manually operated. In this example, the controller 64 is configured to perform clutch disengagement control and brake device intermittent operation control when the button is pressed. A detection device (not shown) may be provided, and the control device 64 may be configured to automatically perform clutch disengagement control and brake device intermittent operation control based on the detection result of the lever position detection device.

[Third Another Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention], [First Alternative Embodiment of the Invention] and [Second Alternative Embodiment of the Invention], the transmission shaft 6 is provided with the brake device 110, and the transmission is performed. Although an example in which the rotation of the shaft 6 can be suppressed has been shown, the first and second transmission clutches 9 and 12 corresponding to the first clutch and the shift member 47 of the auxiliary transmission 44 corresponding to the second transmission device. As long as the transmission shaft is located in the transmission path between them, a configuration in which the brake device 110 is provided on another transmission shaft may be adopted. For example, the transmission shaft 4, the third and fourth main transmission shafts 8 and 11, You may employ | adopt the structure provided with the brake device 110 in the axis | shaft 48 grade | etc.,.

  In the above-mentioned [Best Mode for Carrying Out the Invention], [First Alternative Embodiment of the Invention] and [Second Alternative Embodiment of the Invention], the timer 2 is used as the time during which the brake device 110 is intermittently operated. And 3 are set to the same second set time t2, and the second set time t2 is set to be shorter than the first set time t1, but the set times of the timers 1 to 3 are different set times. Good.

  In the above-mentioned [Best Mode for Carrying Out the Invention], [First Alternative Embodiment of the Invention] and [Second Alternative Embodiment of the Invention], the hydraulic brake cylinder 113 is employed in the brake device 110. However, the actuator that operates the brake device 110 is not limited to a hydraulic actuator, and an electric actuator such as an electric cylinder (not shown) may be employed. Also, the structure of the brake device 110 is not limited to the configuration using the brake drum 111 and the brake arm 112 as long as the structure can suppress the rotation of the transmission shaft 6, and other structures are adopted for the brake device 110. May be.

[Fourth Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention], [First Alternative Embodiment of Invention], [Second Alternative Embodiment of Invention] and [Third Alternative Embodiment of Invention] However, the present invention can be applied not only to agricultural tractors but also to other work vehicles equipped with a gear transmission type first transmission. The present invention can also be applied to a work vehicle equipped with a left crawler traveling device (not shown).

Schematic diagram showing the traveling transmission system Block diagram showing I / O status of control device The figure which shows operation from 1st speed position to 2nd speed position in 1st speed change mode The figure which shows operation from the 1st gear position to the 4th gear position in the 2nd speed change mode The figure which shows the flow of selection of 1st and 2nd transmission mode. The figure which shows the flow of 1st speed change mode The figure which shows the flow of 2nd speed change mode The figure which shows the state of the shift member in the 1-8 speed position, and the 1st and 2nd transmission clutch. Longitudinal rear view showing structure of brake device Longitudinal side view showing the structure of the brake device Flow chart showing control flow of clutch disengagement control Flow chart showing control flow of brake device intermittent operation control Time chart showing operating state of solenoid valve

Explanation of symbols

1 Engine 6 Transmission shaft 9, 12 Transmission clutch (first clutch)
13, 14, 15, 16 Main transmission (first transmission)
44 Subtransmission (second transmission)
47 Shift member 64 Control device (control means)
75,76 Forward and reverse clutch (second clutch)
106 Sub-shift lever (shift lever)
110 Brake device

Claims (4)

The first transmission is provided with a gear transmission type first transmission that is variable in multiple stages to which engine power is transmitted, and a hydraulic multi-plate first clutch is connected in series to the first transmission. And a gear transmission type second transmission that is variable in multiple stages on the lower transmission side of the first clutch, and a hydraulic multi-plate second clutch on the lower transmission side of the second transmission,
A shift lever for shifting the second transmission,
A traveling speed change structure for a work vehicle, comprising control means for operating the first clutch and the second clutch based on a speed change operation of the speed change lever.   2. The traveling speed change structure for a work vehicle according to claim 1, wherein the control means is configured such that the first speed change device is operated to a neutral position based on a speed change operation of the speed change lever. A transmission shaft located on a transmission path between the first clutch and the shift member of the second transmission includes a brake device capable of suppressing the rotation of the transmission shaft.
The traveling speed change structure for a work vehicle according to claim 1 or 2, wherein the control means is configured to operate the brake device based on a speed change operation of the speed change lever.   4. The traveling speed change structure for a work vehicle according to claim 3, wherein the control means is configured so that the brake device operates intermittently based on a speed change operation of the speed change lever.

Images