JP2000094981A - Traveling transmission for working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the convenience in actual use even when an electric system is broken by providing an electric operation type sub-transmission in such a manner as to be operable to a plurality of shift states on the basis of an operating means different from a main transmission, and returning and energizing it to a set shift state in the state where no driving power is supplied. SOLUTION: This transmission system is provided with a hydrostatic continuously variable transmission 7 switchable to forward and backward, which is a main transmission, and a 3-stage shift type sub-gear shifting transmission mechanism 8. The continuously variable transmission 7 has a manual gear shifting lever 7L for shifting operation. A sub-transmission device FH is formed of the sub-gear shifting transmission mechanism 8, a shift control valve, and a neutral selector valve, and the shift control valve and the neutral selector valve are electric operation type switching means. This sub-transmission device FH is also constituted so as to be returned and energized to a standard speed that is a set shift state when an electric system is broken, so that a cutting work can be thereafter continued at a general traveling speed for cutting work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling transmission for a working vehicle, and more particularly to a traveling transmission for a working vehicle having a main transmission and an auxiliary transmission in a traveling transmission system.

[0002]

2. Description of the Related Art Conventionally, in a traveling transmission for a work vehicle, a hydraulic pump driven by an engine and a traveling device are used as the main transmission, as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-76782. And a pair of right and left hydraulic stepless transmissions, each of which is connected to a hydraulic motor to be closed by a closed circuit, and an electromagnetically operated transmission control valve based on a command of an auxiliary transmission switch, which is another operation means different from the operation of the main transmission. By changing the oil flow from the hydraulic pump to the hydraulic motor in two stages of high and low, there is provided a sub-transmission that can be switched between a high-speed and low-speed two-stage shift state. There has been a configuration in which the shift state is alternately switched between a high speed state and a low speed state each time a shift is commanded by a switch.

[0003]

In the above-mentioned conventional configuration, the speed change state of the sub-transmission is changed at a high speed by switching the electromagnetically operated speed-change operation valve by supplying drive power based on the command of the sub-speed switch. Although the configuration is such that the state is alternately switched between the state and the low speed state, for example, when an electrical abnormality such as a failure of an electric system or a power drop due to power (battery) exhaustion occurs, No special consideration was given as to whether or not to shift. For example, if a failure occurs in the electric system while the sub-transmission is being switched to the high-speed state, the sub-transmission is then fixed at the high-speed state, making it difficult to switch to the low-speed state. As a result, the work traveling must be continued while the auxiliary transmission is in the high-speed state,
There is a disadvantage that it may not be possible to work while traveling at low speed.

The present invention has been made in view of such a point, and an object of the present invention is to solve the above-mentioned disadvantages and to solve the problem even in a case where a failure of an electric system occurs. An object of the present invention is to provide a traveling transmission for a working vehicle that can improve usability.

[0005]

According to the first aspect of the present invention, an electrically operated auxiliary transmission capable of performing a shift operation by supplying driving power is provided separately from operating means of the main transmission. A plurality of shift states are provided so as to be operable based on the operation of the operating means, and are configured to return to a set shift state among the plurality of shift states when the driving power is not supplied. Have been.

Accordingly, when the electric system is operating normally, the driving power is supplied based on the operation of the operating means, so that the electrically operated auxiliary transmission changes the speed in each of the plurality of shift states. can do. When a failure occurs in the electric system, the driving power to the electrically operated auxiliary transmission is not supplied, and the gearshift operation is not performed even if the gearshift operation is instructed based on the operation of the operating means. In the state where the driving power is not supplied, the sub-transmission is configured to be returned to the set shift state among the plurality of shift states, so that the sub-transmission is always set to the preset set shift state. It becomes.

That is, if the set shift state is set to, for example, a standard shift state, normal standard work traveling can be appropriately performed even when the electric system fails. If the set shift state is set to, for example, a low-speed side shift state, it is convenient when the low-speed work state mainly needs to be used for work traveling. Thus, the usability in actual use is good.

According to a second aspect of the present invention, in the first aspect, the subtransmission shifts to a transmission state, thereby displaying a shift state for normal work among the plurality of shift states. A hydraulic clutch for normal work to be provided, and other hydraulic clutches for switching to a transmission state to cause a shift state different from the shift state for normal work to appear, and power for driving being supplied, It is provided with an electrically operated switching means for switching a supply state of hydraulic oil so as to selectively bring each of the hydraulic clutches into a transmission state, and the switching means is configured to perform the setting in a state where driving power is not supplied. The shift state is configured to be urged to return to the normal work shift state.

When the electric system is operating normally, for example, when a shift state for normal work is instructed based on the operation of the operating means, the driving power is supplied, and the electric operation type switching is performed. The means switches the supply state of the hydraulic oil so as to bring the normal working hydraulic clutch into the transmission state. Then, the normal work hydraulic clutch is brought into the transmission state, and the gear shift state for the normal work appears. Similarly, when another shift state different from the shift state for normal work is instructed based on the operation of the operation means, the driving power is supplied, and the electrically operated switching means is switched to the above-described state. The supply state of the hydraulic oil is switched to bring the other hydraulic clutches into the transmission state. Then, the other hydraulic clutches are set in the transmission state, and the other shift state is made to appear.

When a failure occurs in the electric system, the driving power is not supplied to the electrically operated switching means. However, when the driving power is not supplied, the switching means sets the set shift state to Since it is configured to be urged to return to the normal work shift state, in the event of such an electrical system failure, the auxiliary transmission is always switched to the normal work shift state and that state is maintained. Will be. Therefore, even after a failure occurs in the electric system, normal work traveling can be continued, and the usability in actual use is improved.

Moreover, since it is a hydraulic clutch type auxiliary transmission, it has a low cost and simple configuration as compared with a configuration in which a pair of left and right hydraulic stepless transmissions are provided as in the above-mentioned prior art, for example. The speed change operation of the sub-transmission can be quickly performed, and there is no inconvenience such as intermittently connecting and disconnecting the separately provided main clutch and stopping the traveling every time a speed change operation is performed, as in a gear-type speed change operation structure. It will be good.

According to the characteristic configuration of the third aspect, in the second aspect, the auxiliary transmission device, as the other hydraulic clutch, is switched to a transmission state so as to be faster than the transmission state for the normal operation. And a low-speed operation hydraulic clutch for displaying a low-speed operation shift state lower than the normal operation speed change state.

Therefore, when the electric system is operating normally, the electric operation type switching means is switched by supplying the driving power based on the operation of the operation means, so that the electric operation type switching means is operated normally. The shift state can be expressed as a shift state, a shift state for movement higher than that, and a shift state for low-speed work that is lower than the shift state for normal work. It is also possible to perform work traveling, and the usability in use is improved not only at the time of abnormality such as failure of the electric system, but also under normal conditions.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A turning control device for a combine as an example of a working vehicle according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, a combine, which is an example of a work vehicle, includes a pair of left and right crawler traveling devices 1L, 1L.
A cutting unit 3 that cuts the planted grain culm and conveys it rearward is connected to the front part of the body frame 2 provided with R so as to be able to move up and down freely,
The machine frame 2 is provided with a threshing device 4 for threshing the harvested culm from the reaping unit 3 and a boarding operation unit 5.

The engine E mounted on the body frame 2
As shown in FIG. 2, the transmission system from the transmission to the traveling devices 1 </ b> L and 1 </ b> R includes a hydrostatic continuously variable transmission 7, which is a main transmission, which can switch between forward and reverse, and a three-stage switching type transmission for auxiliary transmission. The mechanism 8 and the turning transmission mechanism 9 are provided in the order described. Note that a manual transmission operation lever 7 </ b> L for performing a shift operation of the continuously variable transmission 7 is provided in the boarding operation unit 5.

The continuously variable transmission 7 includes traveling devices 1L, 1
The output shaft 7A is attached to the transmission case 11 that supports the axles 10L and 10R of the R. The auxiliary transmission mechanism 8 and the turning transmission mechanism 9 are housed in the transmission case 11. An intermediate transmission shaft 14 to which power is transmitted from an output shaft 7A of the continuously variable transmission 7 via a pair of gears 12 and 13 is supported by the transmission case 11 with one end protruding outside. A cutting output pulley 15 for transmitting power to the cutting unit 3 is mounted on an outer end of the intermediate transmission shaft 14, and the intermediate transmission shaft 14 and the cutting output pulley 15 are provided between the intermediate transmission shaft 14 and the cutting output pulley 15. A one-way clutch 16 that transmits only the forward rotation of the shaft 14 to the cutting output pulley 15 is provided.

The power of the intermediate transmission shaft 14 is transmitted to the input shaft 8A of the auxiliary transmission mechanism 8 via a pair of gears 17 and 18, and the input shaft 8A and the output shaft 8B are connected to each other. Between them, three transmission systems having different transmission ratios of a transmission system for low-speed transmission, a transmission system for medium-speed transmission, and a transmission system for high-speed transmission are interposed, and each transmission system is selected. The three-stage speed change is performed by selectively using the gears.

The transmission system for low-speed transmission includes the input shaft 8
A, the first transmission gear G1 is mounted so as to rotate integrally therewith, and the first passive gear g1, which meshes with and interlocks with the first transmission gear G1, is mounted on the output shaft 8B so as to be rotatable with respect to the output shaft 8B. Between the first passive gear g1 and the output shaft 8B, there is provided a wet multiple disc type first hydraulic clutch C1 for intermittently transmitting power from the first passive gear g1 to the output shaft 8B.

The transmission system for medium-speed transmission includes the input shaft 8
A, the second transmission gear G2 is mounted so as to rotate integrally therewith, and the output shaft 8B is mounted with a second passive gear g2 which meshes with and works with the second transmission gear G2 so as to be rotatable with respect to the output shaft 8B. Between the second passive gear g2 and the output shaft 8B, there is provided a wet-type multi-plate type second hydraulic clutch C2 for interrupting transmission from the second passive gear g2 to the output shaft 8B.

The transmission system for high-speed transmission includes the input shaft 8
A, a third transmission gear G3 is mounted on the output shaft 8B so as to rotate integrally therewith, and a third passive gear g3 meshing with the third transmission gear G3 is mounted on the output shaft 8B so as to be rotatable with respect to the output shaft 8B. A wet-type multi-plate type third hydraulic clutch C3 for intermittently transmitting power from the third passive gear g3 to the output shaft 8B is provided between the third passive gear g3 and the output shaft 8B.

The first, second and third hydraulic clutches C
As shown in FIG. 3, each of 1, 1, and C3 supplies pressure oil to the oil chamber r via each of the hydraulic circuits L1, L2, and L3, and resists the urging force of the spring PB. This is a positive hydraulic clutch that switches to a clutch engaged state in which transmission is performed, and switches to a clutch disengaged state in which transmission is interrupted by the urging force of a spring PB when oil is drained from the oil chamber r.

The auxiliary transmission mechanism 8 is
<1> Pressure oil is supplied to the first hydraulic clutch C1 to switch the first hydraulic clutch C1 to a clutch engaged state,
Further, oil is drained from the second hydraulic clutch C2 and the third hydraulic clutch C3 and the second and third hydraulic clutches C
By switching C2 and C3 to the clutch disengaged state,
A low-speed transmission state (falling speed) is set as a low-speed operation transmission state in which only the low-speed transmission transmission system is switched to the transmission state. <2> Pressure oil is supplied to the second hydraulic clutch C2 and the second hydraulic clutch C2 is switched to a clutch engaged state, and oil is drained from the first hydraulic clutch C1 and the third hydraulic clutch C3 to switch the first and third hydraulic clutches C1 and C3 to the clutch disengaged state. Medium speed transmission state (standard speed) as a shift state for normal work in which only the transmission system for high speed transmission is switched to the transmission state
<3> Pressure oil is supplied to the third hydraulic clutch C3 to switch the third hydraulic clutch C3 to the engaged state, and to drain oil from the first hydraulic clutch C1 and the second hydraulic clutch C2. By switching the first and second hydraulic clutches C1 and C2 to the clutch disengaged state, only the transmission system for high-speed transmission is switched to the transmission state. <4> Oil is drained from the first hydraulic clutch C1, the second hydraulic clutch C2, and the third hydraulic clutch C3, and the first, second, and third hydraulic clutches C1, C2,
By switching C3 to the clutch disengaged state, a neutral state is established in which the entire transmission system is switched to the non-transmission state.

The low-speed transmission state is a transmission state for performing a cutting operation at a low speed which is used when a grain stem to be cut is lying down or the like. The medium-speed transmission state is a transmission state for executing a mowing operation at a medium speed (standard speed) used when the culm to be cut is upright. The high-speed transmission state is a transmission state used, for example, when the vehicle travels on a road at high speed in a non-working state. The neutral state is used, for example, in a case where the mowing unit 3 is driven to perform maintenance work in a state in which the machine body traveling is stopped.

As the shift operation means of the sub-transmission mechanism 8, as shown in FIG.
And each of the hydraulic clutches C1, C2, and C3 between the hydraulic circuits L1, L2, and L3.
2, a shift control valve B1 for supplying pressure oil to any one of C3 and switching to a state of discharging oil from the remaining hydraulic clutch, and a pressure control valve B1 for supplying pressure oil from a hydraulic pump P. State of pressure oil to be supplied to gearbox and transmission control valve B
1 to stop the hydraulic oil supply to each hydraulic clutch C1, C
2, a neutral switching valve B2 that can be switched to an oil discharge state in which oil is discharged from C3.

Here, the shift control valve B1 is a three-position switching type solenoid valve, and has solenoids sb1 and sb2 for switching operation on the left and right. When both of the solenoids sb1 and sb2 are not energized, the oil path switching spool is provided with a spring so as to supply pressure oil to the hydraulic circuit of the second hydraulic clutch C2 (for standard speed). When the solenoid sb1 on the left side is energized while the solenoid sb1 on the left side is energized, the state is switched to a state in which pressure oil is supplied to the first hydraulic clutch C1 (for the falling speed), and the solenoid sb2 on the right side is energized. When done
It is configured to switch to a state in which pressure oil is supplied to the third hydraulic clutch C3 (for traveling speed). The neutral switching valve B2 is configured as a two-position switching electromagnetic valve, is urged to return to the pressure oil supply state by a spring, and is configured to switch to the oil discharge state by energizing the solenoid.

Therefore, the shift control valve B1 and the neutral switching valve B
2 constitutes the electrically operated switching means KS,
In the state where the driving power is not supplied thereto, for example, when a failure of the electric system occurs, such as a disconnection of an electric wiring or an abnormality of an electric control operation of a control device described later, in a set shift state. It is configured to be urged to return to a medium speed transmission state (standard speed) as a shift state for normal work, and even if such an electrical system failure occurs, The mowing work can be continued at the normal running speed for mowing work.

Accordingly, the auxiliary transmission FH is constituted by the auxiliary transmission mechanism 8, the shift control valve B1, and the neutral switching valve B2.

As shown in FIG. 5 and FIG. 6, a push button type first switch SU and an auxiliary speed change operation section 62 comprising a second switch SD are provided on the grip operation section of the speed change operation lever 7L. Based on the information input from each of the switches SU and SD, the first and second electromagnetic control valves B1,
A control device 60 for controlling the operation of B2 is provided.

The control device 60 is provided with a microcomputer, and switches the neutral switching valve B2 to the oil discharging state based on the operation of each switch. A low-speed transmission state in which the control valve B1 supplies pressure oil only to the first hydraulic clutch C1,
The neutral switching valve B2 is in a pressure oil supply state, the transmission control valve B1 is in a medium speed transmission state in which only the second hydraulic clutch C2 is supplied with pressure oil, the neutral switching valve B2 is in a pressure oil supply state, and the transmission control valve B1 is in a transmission state. Each valve is controlled so as to switch to a high-speed transmission state in which pressure oil is supplied only to the third hydraulic clutch C3.

As a specific switching operation, each time the first switch SU is turned on, the transmission control valve B1 and the neutral switching valve B2 are sequentially switched to the high speed side, and the second switch S
Each time D is turned on, the control valves B1 and B2 are sequentially switched to the low speed side. In detail, FIG.
As shown in FIG. 5, when the first switch SU is turned on when the subtransmission mechanism 8 is in the neutral state N, the low speed transmission state F1 is obtained. When the first switch SU is turned on when the sub transmission mechanism F1 is in the low speed transmission state F1, the middle state is obtained. When the first switch SU is turned on in the medium speed transmission state F2, the state becomes the high speed transmission state F3. When the second switch SD is turned on in the medium speed transmission state F2, the medium speed transmission state F2 is established. When the second switch SD is turned on while in the medium speed transmission state F2, the state becomes the low speed transmission state F1,
When the second switch SD is turned on while in the low-speed transmission state F1, the state becomes the neutral state N. Note that, at the beginning of operation when power is supplied to the control device 60, the shift control valve B1 is in the medium speed transmission state, and the neutral switching valve B2 is initially set to the pressure oil supply state.

When a mowing operation is performed in a field or the like, the mowing traveling is executed mainly in the state set to the medium-speed transmission state F2. When the culm to be cut is lying down, the work is switched to the low-speed transmission state F1 and the work is run at a low speed.
The switching operation of the mutual transmission state between the low-speed transmission state F1 and the low-speed transmission state F1 can be appropriately performed even during work traveling. However, from the low speed transmission state F1 to the neutral state N
And the operation of switching from the medium-speed transmission state F2 to the high-speed transmission state F3 may cause inconvenience due to a sudden change in the vehicle speed. So that the control device 6
0 controls the switching operation state.

As shown in FIG. 2, a wet multi-plate type parking brake 19 for stopping the traveling devices 1L and 1R by applying a brake to the output shaft 8B is provided. As shown in the figure, the spring 1b is configured to perform a braking action by the biasing force of the spring 19b, and the hydraulic pump P is operated to supply the pressure oil.
A negative brake cylinder 19a is provided to extend the brake state against the urging force of 9b and release the braking state, and when the engine stops on a slope or the like, the brake state is automatically restored. It is configured as follows.

Next, the turning transmission mechanism 9 will be described with reference to FIG. A forward transmission power transmission gear 33 is mounted on the output shaft 8B of the auxiliary transmission mechanism 8 in an integrally rotating state, and is mounted on the shift shaft 31 rotatably supported by the transmission case 11. A forward transmission passive gear 34 meshing with and interlocking with the gear 33 is mounted in an integrally rotating state. Further, a pair of left and right steering passive gears 35L, 35R and the axle 1
A pair of left and right shift gears 39L, 39R, which are always engaged with and interlock with the wheel bearing dynamic gears 36L, 36R mounted so as to rotate integrally with 0L and 10R, respectively, are rotatably mounted. Then, the left and right shift gears 39L, 39
By moving the R in the axial direction, the left and right wheel bearing dynamic gears 3
6L and 36R are mesh-type linear clutches 37L and 3L.
The first state interlocked with the passive transmission gear 34 via the 7R and the second state interlocked with the passive passive gears 35L, 35R via the meshing steering clutches 38L, 38R. Is configured.

A deceleration / reverse braking shaft 40 is rotatably supported by the transmission case 11.
The transmission transmission gears 41L and 41R for equally transmitting the rotation of the rotation to the passive passive gears 35L and 35R are mounted on the reduction / reverse braking shaft 40 so as to rotate integrally with the transmission passive gears 35L and 35R. A forward rotation passive gear 43, which meshes with a transmission gear unit 42 integrally formed with the gear 34 and in which the rotation of the forward rotation transmission passive gear 34 is reduced and transmitted, is rotatably mounted on the speed reduction / reverse rotation braking shaft 40. I have. Then, between the forward passive gear 43 and the deceleration / reverse braking shaft 40, a spring is operated via a spring in a clutch disengaged state in which transmission from the forward / reverse passive gear 43 to the deceleration / reverse braking shaft 40 is cut off when the supply of hydraulic oil is stopped. There is provided a deceleration wet-type multi-plate type hydraulic clutch 45 which is urged and switches to a clutch-engaged state in which transmission is performed against the urging force with the supply of pressure oil. In other words, by operating the hydraulic clutch 45 to engage the clutch, the rotation of the forward transmission passive gear 34 is transmitted to the transmission gear 42.
-Forward rotation passive gear 43-Reduction gearing 45-Reduction / reverse rotation braking shaft 40-Steering transmission gears 41L, 41R-Steering passive gears 35L, 35R to transmit the vehicle bearing dynamic gears 36L,
36R is configured to be synchronously decelerated.

The output shaft 8B of the auxiliary transmission mechanism 8
A reverse transmission passive gear 47 meshing with and interlocking with a reverse transmission transmission gear 46 mounted in an integrally rotating state is rotatably mounted on the deceleration / reverse braking shaft 40, and the reverse transmission passive gear 47 and the deceleration / reverse braking. Between the shaft 40 and the pressure oil, the transmission from the reverse transmission passive gear 47 to the deceleration / reverse braking shaft 40 is cut off when the pressure oil supply is stopped. A reversing wet-type multi-plate hydraulic clutch 49 is provided, which switches to a clutch-engaged state that transmits power against the force. That is, when the hydraulic clutch 49 is engaged, the rotation of the reverse transmission power transmission gear 46 is changed to the reverse transmission passive gear 47.
The reverse clutch 49, the deceleration / reverse braking shaft 40, the steering transmission gears 41L, 41R, and the passive steering gears 35L, 35R are transmitted to synchronously reversely drive the vehicle bearing dynamic gears 36L, 36R. .

In addition, the deceleration reverse rotation braking shaft 4
A wet multi-plate type braking hydraulic brake 50 which is urged through a spring in a clutch disengaged state for braking 0 and reversibly brakes the deceleration / reverse rotation braking shaft 40 against the urging force due to the supply of pressure oil. Is provided. In other words, the braking operation of the hydraulic brake 50 causes the deceleration reverse rotation braking shaft 40
-Steering transmission gears 41L, 41R-Steering passive gear 35
L, 35R to be transmitted to the wheel bearing dynamic gears 36L, 36R.
Is configured to be braked.

That is, the turning power transmission mechanism 9 causes the rotation of the forward transmission power transmission gear 34 to rotate through the two shift gears 39L and 39R, thereby causing the rotation of the two-wheel bearing to operate. Gear 36L,
36R, the right and left traveling devices 1L and 1R are driven at a constant speed in a straight traveling state. <2> Steering clutch 38
The non-drive turning state in which the turning side of the left and right traveling devices 1L and 1R is turned into a free idling state by turning on the turning side of the left and right traveling devices 1L and 1R by operating the clutch on the turning side among the L and 38R. <3> Steering The turning-side traveling device 1L or 1R of the steering passive gears 35L and 35R is operated by operating the turning-side clutch of the clutches 38L and 38R and engaging the deceleration hydraulic clutch 45. By driving, the left and right traveling devices 1L, 1R make the driving speed of the one on the turning side smaller than the driving speed of the one on the outside of the turning to make a gentle turning, <4> the steering clutches 38L, 38R The turning device on the inside of the turn or 1L or For steering the R passive gear 35L or 35
A pivot turning state in which braking is stopped via R to perform pivot turning, <5> the turning clutch of the steering clutches 38L and 38R is engaged and the hydraulic clutch 49 for reverse rotation is engaged. By driving, the driving device 1L or 1R on the inside of the turning is driven by the one inside the turning among the passive steering gears 35L, 35R, so that the one on the inside of the turning on the left and right traveling devices 1L, 1R is reversely driven. It is configured to be able to perform a switching operation in each of a super-spinning state and a super-spinning state.

As an operating means of the turning transmission mechanism 9, FIG.
As shown in the figure, the shift gears 39L and 39R are respectively set at the positions where the linear clutches 37L and 37R are engaged.
A pair of left and right springs 52 biased to move via L and 51R
L, 52R and the shift gears 39L, 3 against the urging force of the springs 52L, 52R due to the extension operation with the supply of the pressure oil.
A pair of left and right steering cylinders 53L, 53R for moving each of the 9Rs via the arms 51L, 51R at positions where the steering clutches 38L, 38R are engaged, and pressurized oil is supplied to the left and right steering cylinders 53L, 53R. A pair of left and right electromagnetically operated directional changeover valves 56L and 56R that can be switched between a state in which oil is supplied and a state in which oil is drained are provided.

Further, the left and right steering cylinders 53L, 53
When any one of R is in the extension operation state, the pressure oil supplied from the steering cylinders 53L and 53R via the oil passage 54 is supplied to the deceleration hydraulic clutch 45, and the reverse rotation hydraulic pressure is supplied. An electromagnetically operated steering control valve 55 is provided as oil path switching means for mode switching which can be switched between a reverse rotation state supplied to the clutch 49 and a braking state supplied to the hydraulic brake 50 for braking. The oil passage 54
In the middle of the pressure adjustment, pressure adjustment for adjusting the hydraulic pressure of hydraulic oil supplied to the hydraulic clutches 45 and 49 and the hydraulic brake 50 (that is, the turning force) based on the operation state of the turning operation lever 58 described later. A valve 57 is provided. The pressure adjusting valve 57 is configured by an electromagnetic proportional pressure control valve, and switches a spool that is urged to return to the oil discharge side by a spring to a pressure oil supply side by energizing an electromagnetic solenoid. By changing and adjusting the supply current to the solenoid, the position of the spool is changed and the hydraulic pressure of the working oil can be changed and adjusted.

Each of the direction switching valves 56L, 56R, the steering control valve 55, and the pressure adjusting valve 57 is operated based on the operation of a turning operation lever 58 as a turning operation tool provided in the boarding operation section 5, and The switching is controlled by the control device 60. More specifically, a potentiometer 61 is provided at the pivot point of the turning operation lever 58 as operation state detecting means for detecting the operation state thereof.
The control device 60 determines the operation position of the turning operation lever 58 based on the detection information, and switches the valves. That is, as shown in FIG. 5, as the turning operation lever 58 swings in the left or right direction from the straight movement command position TS, the non-drive turning position (R1, L
1), gentle turning position (R2, L2), pivot position (R
3, L3) and the super pivot point (R4, L4) are sequentially operable to be switched. Each time the turning operation lever 58 swings from the straight movement command position TS in one of the left and right directions. Thus, the control device 60 executes the control as follows. When the turning operation lever 58 is located at the straight traveling command position TS, the two-way switching valves 56L and 56R are switched to the oil discharging state and the pressure adjusting valve 57 is switched to the non-operating state (straight traveling state). When the swing operation lever 58 is in the non-drive swing position (L1 or R
When operated in 1), the direction switching valve (56L or 56R) on either the left or right side is switched to the pressure oil supply state, and the pressure adjustment valve 57 is switched to the non-operation state (non-drive turning state). When the turning operation lever 58 is in the gentle turning position (L2 or R2)
Is operated, the directional control valve (56L or 56R) on the left or right side is switched to the pressure oil supply state, the pressure adjustment valve 57 is switched to the operating state, and the steering control valve 55 is switched to the deceleration state. (Slow turning state). The turning operation lever 58 is moved to the pivot position (L3 or R
When operated in 3), the directional control valve (56L or 56R) on either the left or right side is switched to the pressure oil supply state, the pressure regulating valve 57 is switched to the operating state, and the steering control valve 55 is switched to the braking state. (The pivot state). When the turning operation lever 58 is in the pivot position (L4 or R
When operated in step 4), the directional control valve (56L or 56R) on either the left or right side is switched to the pressure oil supply state, the pressure regulating valve 57 is switched to the operating state, and the steering control valve 55 is reversed. (Super turning state).

[Other Embodiments] (1) In the above-described embodiment, a shift operation lever 7L of the main transmission is provided with a first switch SU and a second switch SD as operating means for the auxiliary transmission. Although the configuration in which the shift state is sequentially switched according to the operation has been illustrated, the following configuration may be used instead of such a configuration. A configuration in which the first switch SU and the second switch SD are provided at a portion different from the speed change operation lever. As shown in FIG. 8, four operation switches SN, S1, S2, and S3 corresponding to the respective shift states are provided.
A configuration in which each of the operation switches is controlled to switch to the selected shift state (N, F1, F2, F3) by selectively operating the operation switch. As shown in FIG. 9, a swing operation type auxiliary shift lever 70 is provided.
The control device 60 controls the switching of each of the valves B1 and B2 so that the lever swing operation angle is detected by the potentiometer type detection sensor 71 and the gears are sequentially switched to each of the shift states according to the operation angle. Configuration.

(2) In the above embodiment, a configuration using a three-position switching type electromagnetic control valve as the electrically operated switching means KS has been exemplified. Instead of such a configuration, the following configuration is used. Is also good. For example, as shown in FIG. 10, for each of the hydraulic clutches C1, C2, C3, a two-position switching type electromagnetic control valve V1, V2, which can be individually controlled to switch between a pressure oil supply state and a drainage state. V3,
A first hydraulic clutch C1 and a third hydraulic clutch C
The electromagnetic control valves V1 and V3 for the second hydraulic clutch C2 are both urged to return to the oil discharge state and switched to the hydraulic oil supply state by supplying electric power to the solenoid, whereas the electromagnetic control valves V1 and V3 for the second hydraulic clutch C2 The valve V2 is configured to be urged to return to the pressure oil supply state and switch to the oil discharge state by supplying power to the solenoid. Therefore, when the driving power is no longer supplied, only the electromagnetic control valve V2 enters the pressure oil supply state, and is returned to the medium speed transmission state F2.

(3) In the above-described embodiment, the auxiliary transmission is configured to obtain a desired shift state by selectively switching the plurality of hydraulic clutches to the transmission state. However, the present invention provides such a configuration. For example, a so-called hydrostatic continuously variable transmission (HST) that includes a hydraulic pump and a hydraulic motor as a main transmission and changes and adjusts a traveling speed by changing a swash plate angle is used. The present invention can also be applied to an auxiliary transmission having a configuration in which the transmission state is switched to a plurality of high and low steps by changing the oil flow rate for each continuously variable transmission by independently providing the traveling device.

(4) In the above embodiment, a case has been exemplified in which the subtransmission is configured to be switchable between four states: a low-speed transmission state F1, a medium-speed transmission state F2, a high-speed transmission state F3, and a neutral state N. Is not limited to such a configuration, a configuration that switches between two stages of a high-speed state and a low-speed state, a configuration that switches to a three-stage traveling state of high, medium, and low, a configuration that switches to a traveling state of four or more stages, Further, a configuration that switches to various shift states, such as a configuration in which these are combined with a neutral state, may be used.

(5) In the above-described embodiment, the traveling vehicle of the combine is exemplified as the work vehicle. However, the present invention is not limited to the combine vehicle and can be applied to other work vehicles such as tractors and construction machines.

[Brief description of the drawings]

FIG. 1 is a side view of a combine.

FIG. 2 is a diagram showing a traveling transmission structure.

FIG. 3 is a vertical cross-sectional front view of a transmission mechanism for sub-transmission.

FIG. 4 is a hydraulic circuit diagram

FIG. 5 is a control block diagram.

FIG. 6 is a diagram showing an auxiliary speed change operation unit.

FIG. 7 is a diagram showing an operation state of the auxiliary transmission.

FIG. 8 is a control block diagram of another embodiment.

FIG. 9 is a control block diagram of another embodiment.

FIG. 10 is a hydraulic circuit diagram of another embodiment.

[Explanation of symbols]

 7 Main transmission 7L Operating means 62 Operating means KS Switching means FH Secondary transmission C1, C2, C3 Hydraulic clutch

Continued on the front page (72) Inventor Koji Yamagata 64 Ishizu-Kitacho, Sakai-shi, Osaka F-term in Kubota Sakai Works (reference) 3D039 AA00 AB22 3D040 AA20 AB08 AC56 AE05 AF19

Claims (3)

[Claims] An electrically operated auxiliary transmission capable of performing a shift operation by supplying drive power can be operated in a plurality of shift states based on an operation of an operation means different from an operation means of a main transmission. A traveling transmission device for a working vehicle that is provided and configured to be urged to return to a set shift state among a plurality of shift states when the driving power is not supplied. 2. The normal operation hydraulic clutch, wherein the auxiliary transmission shifts to a transmission state to bring out a normal operation shift state of the plurality of shift states, and switches to a transmission state. And a hydraulic oil for causing the hydraulic clutches to selectively enter a transmission state by being supplied with driving power, in addition to other hydraulic clutches for displaying a gear shift state different from the gear shift state for the normal operation. And an electrically operated switching means for switching the supply state of the motor. When the driving power is not supplied, the switching means returns to the normal operation gear state as the set gear state when the driving power is not supplied. The traveling transmission for a working vehicle according to claim 1, wherein 3. The traveling hydraulic clutch as the other hydraulic clutch, wherein the other hydraulic clutch is switched to a transmission state so as to exhibit a higher speed shifting state than the normal work shifting state. 3. The traveling transmission device for a work vehicle according to claim 2, further comprising: a low-speed work hydraulic clutch for displaying a low-speed work shift state lower than the normal work shift state.