JP3479458B2 - Work vehicle turning control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning operation means for switching a driving state of a pair of left and right traveling devices to a turning operation state, and a turning operation tool for instructing the turning operation means to perform an operation to the turning operation state. The present invention relates to a turning control device for a work vehicle provided.

[0002]

2. Description of the Related Art Conventionally, in a turning control device for a work vehicle, as shown in, for example, Japanese Patent Application Laid-Open No. Hei 8-19304, a plurality of hydraulic clutches (slow clutches) provided in a transmission system for left and right traveling devices are used. The swing clutch 12 and the reverse rotation hydraulic clutch 30) are selectively put into a transmission state to allow a plurality of swing operation states (for example, a slow swing state in which the left and right traveling devices are driven at different speeds, and a left and right traveling device). It is configured to bring out super-spindle turning states that are driven in opposite directions, and corresponds to the turning force (maximum adjustment value of the operating pressure of each hydraulic clutch) in each of the plurality of turning operation states. Is always constant (see FIG. 3 of the above publication).

[0003]

In the above conventional structure, for example, when the vehicle body is traveling in a high-speed traveling state, a predetermined turning operation state is instructed by the turning operation tool, and in the turning operation state. When the operating pressure of the hydraulic clutch is adjusted to the maximum adjustment value, the vehicle turns with a large turning force and at a high speed. When turning at such a high speed, the driver feels anxiety and discomfort. There is room for improvement in this respect.

The present invention has been made by paying attention to this point, and an object thereof is to eliminate the above-mentioned conventional problems and improve driving safety.

[0005]

According to the characterizing feature of claim 1, the turning operation means includes the left and right traveling devices.
The drive state of the
Multiple hydraulically operated friction transmissions that can be exchanged
By selectively switching the moving mechanism to the operating state,
It is configured so that a plurality of turning operation states are revealed, and the vehicle speed detected by the vehicle speed detecting means is equal to or higher than a set speed, or the auxiliary speed change device for traveling speed change is switched to the high speed side set speed change position. if being, in the turning operation while being operated by the command of the rotation operation member, before the selected
By adjusting the hydraulic operating force in the friction transmission mechanism,
Configured to perform a pivoting force adjustment operation of reducing adjust the swirling force me.

That is, when the vehicle speed is equal to or higher than the set speed, or when the auxiliary transmission for traveling gear shifting is switched to the set gear position on the high speed side, the turning operation state is commanded by the turning operation tool. Then, the turning operation means is switched to the turning operation state. In the changed turning operation state, the turning force due to the driving of the left and right traveling devices is adjusted to be reduced, so that a high turning force and a large turning force are applied. It is possible to prevent the vehicle from turning and to improve traveling safety. In addition, a hydraulically operated friction transmission mechanism
Multiple turning operations by selectively switching to the operating state
Since it is configured to show the state, turning operation state switching
Although the replacement operation can be performed quickly and efficiently,
By adjusting the hydraulic operating force in the friction transmission mechanism
Since the turning force adjustment operation is executed, turning force adjustment is performed.
To complicate the configuration, such as providing a special adjustment mechanism for
Without being able to improve driving safety.
It was

According to the characteristic configuration of claim 2, in the turning operation means , the turning operation tool instructs a set turning operation state in which the turning force is the largest among the plurality of turning operation states. Only then is the turning force adjustment operation performed.

Therefore, in the state where the set turning operation state having the largest turning force among the plurality of turning operation states is instructed, turning the vehicle at high speed causes anxiety and discomfort to the driver. However, when the turning operation state with a small turning force is instructed, it is possible that the steering operability is rather decreased if the turning force adjustment operation is performed, so the turning force is the largest. By executing the turning force adjusting operation only when the set turning operation state is instructed, it is possible to avoid unnecessarily lowering the steering operability.

According to the feature configuration described in claim 3, in claim 2, wherein the turning operation manually stage, performs the turning force adjustment operation by adjusting the hydraulic operating force in said selected frictional transmission mechanism Is configured to.

Since the turning force adjusting operation is executed by adjusting the hydraulic operating force in the selected friction transmission mechanism, the structure is not complicated, such as providing a special adjusting mechanism for adjusting the turning force. , It became possible to improve driving safety.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A turn control apparatus for a combine as an example of a work 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 traveling devices 1L, 1 of a crawler type.
A cutting unit 3 for cutting the planted culms and transporting them to the rear is connected to the front part of the machine body frame 2 provided with R so as to be vertically movable,
The machine frame 2 includes a threshing device 4 for threshing the cut culms from the reaping unit 3 and a boarding operation unit 5.

Engine E mounted on the body frame 2
As shown in FIG. 2, a transmission system from the traveling devices 1L and 1R to the traveling devices 1L and 1R includes a hydrostatic stepless transmission 7 which is a main transmission and is capable of forward / reverse switching, and a sub-transmission 8 having a three-stage switching.
And the turning transmission mechanism 9 are provided in that order. A manual gear shift operating lever 7L for shifting the continuously variable transmission 7 is provided in the boarding operation section 5.

The continuously variable transmission 7 includes traveling devices 1L and 1L.
The output shaft 7A is attached to the mission case 11 supporting the respective axles 10L and 10R of the R in a state of being inserted. The auxiliary transmission 8 and the turning transmission mechanism 9
Is installed in the mission case 11. An intermediate transmission shaft 14 to which power is transmitted from the output shaft 7A of the continuously variable transmission 7 via the gear pairs 12 and 13 is supported on the transmission case 11 with one end thereof protruding outward. A reaper output pulley 15 for transmitting power to the reaper 3 is attached to an outer end portion of the intermediate transmission shaft 14, and the intermediate transmission shaft 14 and the reaper output pulley 15 are provided.
A one-way clutch 16 that transmits only the forward rotation of the intermediate transmission shaft 14 to the reaping output pulley 15 is interposed between and.

The power of the intermediate transmission shaft 14 is transmitted to the input shaft 8A of the auxiliary transmission 8 through the pair of gears 17 and 18, and is provided between the input shaft 8A and the output shaft 8B. The transmission system for low speed transmission, the transmission system for medium speed transmission, and the transmission system for high speed transmission have three different transmission ratios, and each transmission system is selectively used. By selecting and using it, three-speed shifting is performed.

The transmission system for low speed transmission is the input shaft 8
The first transmission gear G1 is attached to A so as to rotate integrally, and the first passive gear g1 which meshes with and interlocks with the first transmission gear G1 is attached to the output shaft 8B so as to be rotatable with respect to the output shaft 8B. A wet multi-plate type first hydraulic clutch C1 is provided between the first passive gear g1 and the output shaft 8B so as to connect and disconnect the transmission from the first passive gear g1 to the output shaft 8B.

The transmission system for medium speed transmission is the input shaft 8
A is installed in a state in which the second transmission gear G2 is integrally rotated, and a second passive gear g2 that meshes with and interlocks with the second transmission gear G2 is installed in the output shaft 8B in a rotatable state with respect to the output shaft 8B. A wet multi-plate second hydraulic clutch C2 is provided between the second passive gear g2 and the output shaft 8B so as to connect and disconnect the transmission from the second passive gear g2 to the output shaft 8B.

The transmission system for high speed transmission is the input shaft 8
The third transmission gear G3 is attached to A so as to rotate integrally, and the third passive gear g3 which meshes with and interlocks with the third transmission gear G3 is attached to the output shaft 8B so as to be rotatable with respect to the output shaft 8B. Between the third passive gear g3 and the output shaft 8B, a wet multi-plate third hydraulic clutch C3 for connecting and disconnecting the transmission from the third passive gear g3 to the output shaft 8B is provided.

The first, second and third hydraulic clutches C
As shown in FIG. 3, each of 1, C2, C3 resists the biasing force of the spring PB as the pressure oil is supplied to the oil chamber r via the hydraulic circuits L1, L2, L3. It is a positive hydraulic clutch that is switched to a clutch engaged state for transmission, and is switched to a clutch disengaged state in which transmission is disengaged by the biasing force of the spring PB as oil is discharged from the oil chamber r.

The sub-transmission device 8 is <1> first
The hydraulic oil is supplied to the hydraulic clutch C1 of the first hydraulic clutch C1 to switch the first hydraulic clutch C1 to the clutch-engaged state, and
By discharging the oil from the hydraulic clutch C2 and the third hydraulic clutch C3 and switching the second and third hydraulic clutches C2 and C3 to the clutch disengaged state, only the transmission system for low speed transmission is switched to the transmission state. The transmission state (falling speed) is established, and <2> pressure oil is supplied to the second hydraulic clutch C2 to switch the second hydraulic clutch C2 to the engaged state, and the first hydraulic clutch C1 and the third hydraulic clutch C3
By draining oil from the hydraulic clutch C3 and switching the first and third hydraulic clutches C1 and C3 to the clutch disengaged state, only the transmission system for medium 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 into the clutch-engaged state, and the third hydraulic clutch C3 is discharged from the first hydraulic clutch C1 and the second hydraulic clutch C2. By oiling and switching the first and second hydraulic clutches C1 and C2 to the clutch disengaged state, a high speed transmission state (moving traveling speed) in which only the transmission system for high speed transmission is switched to the transmission state, <4> Oil is discharged 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,
By switching C2 and C3 to the clutch disengaged state, a neutral state is achieved in which the entire transmission system is switched to the non-transmission state.

As a shift operation means of the sub transmission 8,
As shown in FIG. 4, the hydraulic pump P and the hydraulic circuits L for the first, second and third hydraulic clutches C1, C2 and C3 are shown.
1, L2, L3, the respective hydraulic clutches C1, C2,
A speed change control valve B1 for supplying pressure oil to any one of C3 and for discharging the remaining hydraulic clutch, and pressure oil from the hydraulic pump P is supplied to the speed change control valve B1. Pressure oil supply state to be turned on, and pressure oil supply to the speed change control valve B1 is stopped to cause the hydraulic clutches C1, C2,
A neutral switching valve B2 is provided which can be switched from C3 to a drained state in which oil is drained.

Here, the shift control valve B1 is a solenoid valve of a three-position switching type, and is provided with solenoids sb1 and sb2 for switching operation on the left and right. When both solenoids sb1 and sb2 are not energized, the oil passage switching spool is set to the spring so that the pressure oil is supplied to the hydraulic circuit of the second hydraulic clutch C2 (for standard speed). When the solenoid sb1 on the left side is energized by being urged to return to the middle position by the, the state in which pressure oil is supplied to the first hydraulic clutch C1 (for the fall speed) is switched, 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 biased 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.

As shown in FIGS. 5 and 6, the grip operation portion of the gear shift operation lever 7L is provided with a push button type first switch SU and a sub gear shift operation portion 62 including a second switch SD. Based on the information input from each switch SU, 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 configured to include a microcomputer, and based on the operation of each switch, the neutral switching valve B2
Is switched to the oil draining state, the neutral switching valve B2 is in the pressure oil supplying state, and the shift control valve B1 is in the low speed transmission state in which the pressure oil is supplied only to the first hydraulic clutch C1, the neutral switching valve B.
2 is in the pressure oil supply state, the speed change control valve B1 is in the medium speed transmission state in which pressure oil is supplied only to the second hydraulic clutch C2, the neutral switching valve B2 is in the pressure oil supply state, and the speed change control valve B1 is in the third state. It is configured to control each valve so as to switch to each state of the high speed transmission state in which the pressure oil is supplied only to the hydraulic clutch C3.

As a concrete switching operation, every time the first switch SU is turned on, the shift control valve B1 and the neutral switching valve B2 are sequentially switched to the high speed side, and the second switch S is operated.
Each time D is turned on, the control valves B1 and B2 are switched to the low speed side in sequence. More specifically, FIG.
As shown in, when the auxiliary transmission 8 is in the neutral state N, when the first switch SU is turned on, the low speed transmission state F1 is established, and when it is in the low speed transmission state F1, the first switch SU is
When the ON operation is performed, the medium speed transmission state F2 is set, when the first switch SU is turned on in the medium speed transmission state F2, the high speed transmission state F3 is set, and when the second switch SD is turned on when the high speed transmission state F3 is set. Medium speed transmission state F2
And the second switch S when in the medium speed transmission state F2.
When D is turned on, the low-speed transmission state F1 is set. When the second switch SD is turned on while the low-speed transmission state F1 is set, the neutral state N is set. In the initial stage of operation when the control device 60 is powered on, the shift control valve B1 is in the medium speed transmission state, and the neutral switching valve B2 is initially set in the pressure oil supply state.

Further, as shown in FIG. 2, a wet multi-plate type parking brake 19 for braking the output shaft 8B to stop and hold the traveling devices 1L, 1R is provided, and this parking brake 19 is shown in FIG. As shown in the figure, the spring 1 is configured so that it is braked by the urging force of the spring 19b and the spring 1 is supplied as the hydraulic pump P is operated to supply the pressure oil.
A negative-type brake cylinder 19a is provided which extends the brake 9b to release the braking state against the urging force of 9b, and automatically returns to the braking state when the engine stops in the middle of a slope. Is configured.

Next, the turning transmission mechanism 9 will be described with reference to FIG. Output shaft 8B of the auxiliary transmission 8
In addition, a forward rotation transmission gear 33 is mounted in an integrally rotating state, and a forward rotation transmission passive gear that meshes with the forward rotation transmission gear 33 and is linked to a shift shaft 31 rotatably supported by the transmission case 11. The gear 34 is mounted so as to rotate integrally. Further, the shift shaft 31 includes a pair of left and right steering passive gears 35L and 35R, and the axle shaft 10.
A pair of left and right shift gears 39L and 39R, which are always meshed with and interlocked with vehicle bearing dynamic gears 36L and 36R, which are mounted to rotate integrally with L and 10R, are rotatably mounted. Then, the left and right shift gears 39L, 39R
Of the left and right car bearing dynamic gears 36 by moving the
L and 36R are meshing linear clutches 37L and 37
A first gear that interlocks with the normal rotation transmission passive gear 34 via R
It is configured to be switchable between a state and a second state in which the passive steering gears 35L and 35R are interlocked with each other via the meshing type steering clutches 38L and 38R.

A vehicle speed sensor SE for detecting the traveling speed of the vehicle body on the basis of the rotation speed of the shift shaft 31 is provided.

A deceleration / reverse rotation braking shaft 40 is rotatably supported by the mission case 11, and the deceleration / reverse braking shaft 40 is rotatably supported.
The steering transmission gears 41L and 41R, which equally reduce the speed of the rotation of the steering passive gears 35L and 35R, are mounted on the deceleration / reverse braking shaft 40 so as to rotate integrally with the steering passive gears 35L and 35R. The forward rotation passive gear 43, which meshes with the transmission gear portion 42 formed integrally with the gear 34 and transmits the rotation of the forward rotation transmission passive gear 34 by deceleration, is rotatably mounted on the deceleration / reverse rotation braking shaft 40. There is. Then, between the forward rotation passive gear 43 and the deceleration / reverse rotation braking shaft 40, the transmission from the forward rotation passive gear 43 to the deceleration / reverse rotation braking shaft 40 is interrupted when the pressure oil supply is stopped. A wet multi-plate hydraulic clutch 45 for deceleration is provided, which is energized and switches to a clutch engaged state in which transmission is performed against the energizing force when the pressure oil is supplied. That is, by operating the hydraulic clutch 45 to engage the clutch, the rotation of the normal rotation transmission passive gear 34 is transmitted.
The normal rotation passive gear 43, the deceleration clutch 45, the deceleration reverse rotation braking shaft 40, the steering transmission gears 41L and 41R, and the steering passive gears 35L and 35R are transmitted to the car bearing dynamic gear 36L,
36R is configured to drive the synchronous deceleration.

A reverse rotation transmission passive gear 47, which meshes with and interlocks with a reverse rotation transmission gear 46 mounted integrally on the output shaft 8B of the auxiliary transmission 8, is rotatably attached to the deceleration reverse braking shaft 40. A spring is placed between the reverse gear transmission passive gear 47 and the deceleration reverse rotation braking shaft 40 in a clutch disengaged state that cuts off the transmission from the reverse rotation transmission passive gear 47 to the deceleration reverse rotation braking shaft 40 when the pressure oil supply is stopped. There is provided a wet multi-plate hydraulic clutch 49 for reverse rotation, which is urged through the operation and is switched to a clutch engagement state in which transmission is performed against the urging force when pressure oil is supplied. That is, by operating the hydraulic clutch 49 to be engaged, the rotation of the reverse rotation transmission gear 46 is rotated by the reverse rotation transmission passive gear 47, the reverse rotation clutch 49, the deceleration reverse rotation braking shaft 40, and the steering transmission gear 4.
1L, 41R and steering passive gears 35L, 35R are transmitted to drive the bearing dynamic gears 36L, 36R in a synchronous reverse rotation.

Further, when the pressure oil supply is stopped, the deceleration reverse rotation braking shaft 4
A wet multi-plate hydraulic brake 50 for braking, which is urged by a spring to a clutch disengaged state for braking 0 and reversibly brakes the deceleration / reverse braking shaft 40 against the urging force associated with the supply of pressure oil. Is provided. That is, 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 and 35R are transmitted to the car bearing dynamic gears 36L and 36R.
Is configured to brake.

That is, the turning transmission mechanism 9 causes the rotation of the forward rotation transmission passive gear 34 to rotate in both vehicle bearings via both shift gears 39L and 39R by <1> activating both of the linear clutches 37L and 37R. Gear 36L,
36R, the left and right traveling devices 1L and 1R are driven at a constant speed in a straight traveling state. <2> Steering clutch 38
A non-driving turning state in which the driving of one of the left and right traveling devices 1L and 1R is turned off and a free idling state is set by operating the turning side of L and 38R with a clutch. <3> Steering Of the clutches 38L and 38R, the one on the turning side is engaged with the clutch, and the hydraulic clutch 45 for deceleration is also engaged on the clutch, so that the traveling device 1L or 1R on the turning side of the passive steering gears 35L and 35R is operated. By driving the left and right traveling devices 1L and 1R, the driving speed of the one on the turning side is made slower than the driving speed of the one on the outside of the turning to make a gentle turning state. <4> Steering clutches 38L, 38R Of the turning devices, the one on the turning side is engaged with the clutch and the hydraulic brake 50 for braking is actuated, so that the traveling device 1L on the inside of the turning or For steering the R passive gear 35L or 35
In the pivotal turning state in which braking is stopped via R to perform pivotal turning, <5> The steering clutch 38L or 38R, which is on the turning side, is engaged and the hydraulic clutch 49 for reverse rotation is engaged. By driving the driving device 1L or 1R on the inner side of the turning by the one on the inner side of the turning of the steering passive gears 35L, 35R, the one on the inner side of the turning of the left and right traveling devices 1L, 1R is driven in reverse. It is configured so that the switching operation can be performed in each of the super-confidential turning state in which the super-confidential turning is performed.

As an operating means of the turning transmission mechanism 9, FIG.
As shown in FIG. 3, the shift gears 39L and 39R are respectively moved to the positions where the straight clutches 37L and 37R are engaged.
A pair of left and right springs 52 for urging and moving via L and 51R
The shift gears 39L and 3R are opposed to the biasing forces of the springs 52L and 52R by extending the L and 52R together with the pressure oil supply.
A pair of left and right steering cylinders 53L and 53R for moving the respective 9Rs to the positions where the steering clutches 38L and 38R are engaged via the arms 51L and 51R are provided, and pressure oil is provided to the left and right steering cylinders 53L and 53R. A pair of left and right electromagnetically operated directional control valves 56L, 56R are provided which can be switched between a state of supplying oil and a state of discharging oil.

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

Each of the direction switching valves 56L and 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. The control device 60 is configured to perform a switching operation. More specifically, the turning operation lever 5
8 is provided with a potentiometer 61 as an operation state detecting means for detecting the operation state of the swing fulcrum, and the control device 60 determines the operation position of the turning operation lever 58 on the basis of the detection information, and each of the valves is operated. It is designed to switch between.

That is, as shown in FIG. 5, as the turning operation lever 58 is swung from the straight-ahead command position TS to either the left or right direction, the non-driving turning position (R1, L1) and the gentle turning position (R2) are set. , L2), the pivot position (R3, L
3), the turning operation lever 58 is configured so that it can be sequentially switched to each of the super-position turning positions (R4, L4).
The control device 60 executes the control as described below when the vehicle swings from the straight-ahead command position TS in either the left or right direction. When the steering lever 58 is located at the straight travel command position TS, the bidirectional switching valves 56L and 56R are switched to the oil draining state and the pressure adjusting valve 57 is switched to the inoperative state (straight traveling state). When the turning operation lever 58 is in the non-driving turning position (L1 or R
When operated to 1), the directional switching valve (56L or 56R) on either the left or right side is switched to the pressure oil supply state and the pressure adjusting valve 57 is switched to the non-operating state (non-drive turning state). The turning operation lever 58 is in the gently turning position (L2 or R2)
When it is operated to, the direction switching valve (56L or 56R) on either the left or right side is switched to the pressure oil supply state, the pressure adjusting 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 set to the solid turning position (L3 or R
When operated in 3), the direction switching valve (56L or 56R) on either the left or right side is switched to the pressure oil supply state, the pressure adjusting valve 57 is switched to the operating state, and the steering control valve 55 is in the braking state. Switch to (Turning to the ground). The turning operation lever 58 moves to the super-sight turning position (L4 or R
4), the direction switching valve (56L or 56R) on either the left or right side is switched to the pressure oil supply state, the pressure adjusting valve 57 is switched to the operating state, and the steering control valve 55 is in the reverse rotation state. Switch to (super turning state).

The control device 60 includes a turning operation lever 58.
As the amount of turning operation of the hydraulic clutch increases, each of the hydraulic clutches 45, 49 and the hydraulic brake 50 as a friction transmission mechanism.
And the rate of change of the oil pressure becomes
The change characteristic is set so that the operation amount is small in the small region and is large in the large region, and the operation of the pressure control valve is controlled. Further, if the vehicle speed detected by the vehicle speed sensor SE is equal to or higher than the set speed, or if the auxiliary transmission 8 is switched to the high speed transmission state, the control device 60 controls the turning operation lever 58.
In the turning operation state instructed by, the turning force adjusting operation for reducing and adjusting the hydraulic pressure (corresponding to the turning force) is executed.

More specifically, as shown in FIG. 8, as the turning operation amount of the turning operation lever 58 increases from the straight-ahead command position TS, the turning operation state is switched as described above. Pressure adjustment for changing and adjusting the hydraulic pressure of the hydraulic clutches 45, 49 and the hydraulic brake 50 selected corresponding to each of the operation positions (areas) so that the hydraulic pressure increases as the operation amount increases. It is configured to control the hydraulic pressure by the valve 57. With this configuration, the human operation interval for the lever operation corresponds to the actual turning operation state of the vehicle body, and operability is improved. ing.

The control device 60 determines whether the vehicle speed detected by the vehicle speed sensor SE is equal to or higher than a set value, or whether the auxiliary transmission 8 has been switched to a high speed transmission state or is in a sudden turn suppression state. If it is determined that it is not in the above-mentioned sudden turning suppression state, it is determined as shown in FIG.
As shown in the above, in each of the turning operation states of the gentle turning state, the turning point turning state, and the super turning point turning state, with the control characteristic of changing and adjusting the hydraulic pressure until it reaches almost the maximum value of the adjustable region, It is configured to control the operation of the pressure regulating valve 57. Then, when the control device 60 determines that it is in the sudden turning suppression state, as shown in FIG. 8B, the oil of the pressure adjusting valve 57 is changed in each of the turning operation states instructed by the turning operation lever 58. By controlling the pressure (corresponding to the turning force) to be equal to or lower than the set value set to a value lower than the above-mentioned maximum value, the turning force is adjusted by reducing the turning force. With this configuration, it is possible to prevent the turning operation from being performed with a large turning force while the vehicle is traveling at high speed, and improve the traveling safety.

Therefore, the directional control valves 56R, 56L,
A hydraulic operating mechanism including a steering control valve 55, a pressure adjusting valve 57, a hydraulic pump P, and the turning transmission mechanism 9
Then, the control device 60 or the like constitutes the turning operation means.

[Other Embodiment] (1) In the above embodiment, the sudden turning suppression state is as follows.
Two conditions, that is, the vehicle speed detected by the vehicle speed sensor SE is equal to or higher than a set value and that the auxiliary transmission 8 is switched to the high speed transmission state, are discriminated, and any one of the conditions is determined. If the above condition is satisfied, the turning force adjusting operation is executed. However, as a configuration for determining whether or not only one of the above two conditions is satisfied, based on the determination result. Alternatively, the turning force adjusting operation may be performed.

(2) In the above embodiment, when it is determined that the sudden turning suppression state is in effect, the turning force adjusting operation is executed in each of the corresponding plurality of turning operation states among the plurality of turning operation states. However, instead of such a configuration, it is determined that the sudden turning suppression state is present, and the "super-communication" is set as the set turning operation state in which the turning force is the largest among the plurality of turning operation states. The turning force adjusting operation may be executed only when the "ground turning state" is instructed.

(3) In the above-described embodiment, when the turning force adjusting operation is executed, the maximum value of the hydraulic pressure is suppressed to be equal to or less than the preset set value. The maximum value of the hydraulic pressure may be changed and set so as to be as small as possible.

(4) In the above embodiment, the hydraulic pressure increases as the operation amount of the turning operation tool increases, and the rate of change of the hydraulic pressure is small in the region where the operation amount is small. ,
The change amount is set so that the operation amount becomes large in the large region, and the operation of the pressure adjusting means (pressure adjusting valve) is controlled, but the present invention is not limited to such a configuration. The hydraulic pressure may change in a proportional state with a linear change characteristic as the operation amount increases.

(5) In the above embodiment, for each of the hydraulic clutches 45, 49 and the hydraulic brake 50,
Three-position switching type operation as oil passage switching means for switching the oil passage for supplying hydraulic oil so that the pressure oil having the hydraulic pressure adjusted by the pressure adjusting valve 57 as the pressure adjusting means Q is selectively supplied. Although the configuration including the directional control valve 55 is illustrated, the configuration described below may be used instead of such a configuration.

As shown in FIG. 9, each hydraulic clutch 4
5, 49 and hydraulic brakes 50 are respectively provided with pressure adjusting valves 63, 64, 65 in the pressure oil supply passages,
It is also possible to selectively actuate one of the pressure adjusting valves to actuate any one of the hydraulic clutches 45, 49 and the hydraulic brake 50, and also to perform pressure adjustment separately. Therefore, each of the pressure adjusting valves 63, 64, 65 constitutes the pressure adjusting means Q.

(6) In the above embodiment, the case where the swing operation lever for swinging operation is used as the swing operation tool is exemplified. However, instead of such a swing operation type operation tool, a steering handle of a passenger car is used. A rotary operation type turning operation tool may be used.

(7) In the above embodiment, the potentiometer is used as the operation state detecting means for detecting the operation state of the turning operation tool (turning operation lever).
Instead of such a configuration, a switch is provided for individually detecting that each of the straight drive command position, the non-drive turning position, the gentle turning position, the land turning position, and the super land turning position has been sequentially switched. It may be configured to detect the operation state.

(8) In the above embodiment, the turning operation means is configured to electrically switch and control the hydraulic operating mechanism based on the operating state of the turning operation tool. However, instead of such a configuration, the turning operation is performed. It may be configured to be mechanically linked to the tool so as to switch to each of the turning states corresponding to each of the operation positions .

(9) In the above-described embodiment, the gear shift operation lever 7L of the main transmission is provided with the first switch SU and the second switch SD as the operating means for the auxiliary transmission.
Although the configuration in which the shift state is sequentially switched according to the operation of each switch is 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 different parts from the shift operation lever. Four operation switches corresponding to each of the speed change states (N, F1, F2, F3) are provided, and control is performed by selectively operating each operation switch to switch to the selected speed change state. Configuration. Equipped with a swing operation type auxiliary shift lever, the potentiometer type detection sensor detects the lever swing operation angle,
A configuration in which control is performed such that the shift states are sequentially switched according to the operation angle.

(10) In the above-described embodiment, the sub-transmission device is configured to obtain a desired speed change state by selectively switching a plurality of hydraulic clutches to the transmission state, but the present invention has such a structure. Not limited to this, for example, a so-called hydrostatic continuously variable transmission (HST) that includes a hydraulic pump and a hydraulic motor as a main transmission and that adjusts the traveling speed by changing the swash plate angle is provided. The present invention can be applied to a sub-transmission device having a configuration in which the traveling device is independently provided, and the shift state is switched to a plurality of high and low stages by changing the oil flow rate for each continuously variable transmission.

(11) In the above embodiment, the case where the auxiliary transmission is configured to be switchable among four states of the low speed transmission state F1, the medium speed transmission state F2, the high speed transmission state F3, and the neutral state N has been illustrated. However, not limited to such a configuration, a configuration that switches to two stages of a high-speed state and a low-speed state, a configuration that switches to a three-stage running state of high, medium, and low, a configuration that switches to a four-stage or more running state, Further, it may be configured to switch to various shift states such as a configuration in which they are combined with a neutral state.

The present invention can be applied to various work vehicles other than combine harvesters.

[Brief description of drawings]

FIG. 1 Side view of combine

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

FIG. 3 is a vertical sectional front view of the auxiliary transmission device.

[Fig. 4] Hydraulic circuit diagram

FIG. 5 is a control block diagram.

FIG. 6 is a diagram showing an auxiliary shift operation unit.

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

FIG. 8 is a characteristic diagram showing changes in hydraulic pressure.

FIG. 9 is a hydraulic circuit diagram of another embodiment.

[Explanation of symbols]

1R, 1L traveling device 45, 49, 50 Friction transmission mechanism 58 Turning operation tool

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-9-104356 (JP, A) JP-A-6-270833 (JP, A) JP-A-5-193514 (JP, A) JP-A-5- 176622 (JP, A) JP 5-262151 (JP, A) JP 62-152981 (JP, A) Actual flat 5-5668 (JP, U) Actual flat 7-8162 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B62D 11/00

Claims (3)

(57) [Claims] 1. A work vehicle provided with a turning operation means for switching a driving state of a pair of left and right traveling devices to a turning operation state, and a turning operation tool for instructing the turning operation means to perform an operation to the turning operation state. In the turning control device, the turning operation means sets the driving states of the left and right traveling devices to a plurality of turning forces different from each other.
It is provided so that it can be switched to the turning operation state, and
The hydraulically operated friction transmission mechanism is selectively switched to the operating state.
To display the plurality of turning operation states.
If the vehicle speed detected by the vehicle speed detecting means is equal to or higher than the set speed, or if the auxiliary speed change device for traveling speed change is switched to the high speed set speed change position, In the turning operation state operated by the command , before the selected
By adjusting the hydraulic operating force in the friction transmission mechanism,
Reduction of the working vehicle that is configured to perform a turning force adjustment operation for adjusting the turning control apparatus swirling force me. Wherein said turning operation means executes the swirling force adjusting operation only when the largest set turning operation state swirling force of the plurality of turning operation state by the turning operation member is being commanded The turning control device for a work vehicle according to claim 1, which is configured to perform. 3. The turning of the work vehicle according to claim 2 , wherein the turning operation means is configured to execute the turning force adjusting operation by adjusting a hydraulic operation force of the selected friction transmission mechanism. Control device.