JP3489995B2 - Work vehicle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work vehicle provided with a control means for operating an actuator based on an operation of a gear shift operation tool, and gear-shifting a transmission by a driving force of the actuator to obtain a predetermined gear. Regarding

[0002]

2. Description of the Related Art As a work vehicle constructed as described above, there is one disclosed in Japanese Patent Laid-Open No. 9-240297.
In this conventional example, a synchromesh gear speed change system, a hydraulic cylinder as an actuator for shifting the gear, and a hydraulic clutch interposed in a transmission system are provided, and the hydraulic oil is supplied to and discharged from the hydraulic cylinder during a speed change operation. And a hydraulic control system for turning on and off the hydraulic clutch.When shifting is performed by the shift lever, the shift is started by operating the hydraulic cylinder after the hydraulic clutch is disengaged. The operation of engaging the hydraulic clutch is performed when the operation is completed.

[0003]

However, in the conventional example,
After the engine is stopped with the transmission set to the shift position, the gear cannot be changed even if the gear shift lever is operated.For example, stop the engine with the transmission set to the high speed stage. After that, when the engine is started and the vehicle is about to start running, it will start suddenly and there is room for improvement. In order to eliminate this inconvenience, it is necessary to check the gear stage when starting traveling and operate the gear shift lever if necessary, but this operation at the time of starting the engine is troublesome. is there.

An object of the present invention is to prevent a sudden start without performing an operator's troublesome operation when the engine is started to start traveling even if the transmission is set to the gear stage when the engine is stopped. The point is to reasonably construct a work vehicle that can.

[0005]

The first feature of the present invention (claim 1) is to operate the actuator based on the operation of the gear shift operation tool, and to change the speed of the transmission by the driving force of the actuator to thereby perform a predetermined operation. In a work vehicle equipped with a control unit for obtaining the gear position, a state in which the gear position of the transmission is maintained based on an operation of stopping an engine provided in the vehicle body, and a state in which the gear set is set to a preset gear change target. together when the control mode of the control means is configured to select one of
In addition, restart the engine within a predetermined time after stopping the engine.
If the parking brake is set to the braking state without moving,
Alternatively, if a predetermined time has elapsed after the engine stop operation,
Power is transmitted to the wheels from the selected shift control mode.
Of the control means to switch the neutral position to the gear shift target.
The point is that the control mode is changed .

A second feature (claim 2) of the present invention is that the shift
Operate the actuator based on the operation of
The speed of the transmission is changed by the driving force of the actuator of
A work vehicle provided with a control means for obtaining a constant gear, car
Based on the operation to stop the engine equipped to the body, change the transmission
The state that the speed is maintained and the transmission is set in advance
The above-mentioned control so as to select one of the states set to the target
The control mode of the means is set and the engine is stopped.
If the engine is restarted within the specified time after operation,
The gear is set to the selected gear and the engine stops.
Parking brake without restarting the engine within the specified time after operation.
If the brake is set to the braking state, or if the engine
When the predetermined time has elapsed after the stop operation, the selected speed change
The neutral position where power is not transmitted to the wheels from the control mode
Change the control mode of the control means to switch to the target
There is a point to be.

A third feature (claim 3) of the present invention is that the shift
Operate the actuator based on the operation of
The speed of the transmission is changed by the driving force of the actuator of
A work vehicle provided with a control means for obtaining a constant gear, car
Based on the operation to stop the engine equipped to the body, change the transmission
The state that the speed is maintained and the transmission is set in advance
The above-mentioned control so as to select one of the states set to the target
The control mode of the means is set and the engine is stopped.
If the engine is not restarted within the specified time after operation , and
When the parking brake is not set to the braking state
When the time elapses, the control mode of the selected shift state
Switch the neutral position where power is not transmitted to the wheels to the gear shift target
Thus, the control mode of the control means is changed .

A fourth feature of the present invention (claim 4) is the claim.
In any one of 1 to 3, the shift target selected when the engine is stopped while the transmission is set to a high speed traveling state is the lowest speed.
There is .

The fifth feature of the present invention (claim 5) is the claim.
In any one of 1 to 3, the transmission is in a high speed range,
The engine is configured to be able to perform a gear shift operation in either the medium speed range or the low speed range, and the engine is stopped while the gear shift operation is being performed in the middle speed range or the low speed range. In this case, the control mode of the control means is set so as to maintain the shift speed during the engine stop operation.

[Operation] According to the features of the first to third aspects of the invention, even if the transmission is set to a predetermined gear stage when the engine is stopped, the control means preliminarily sets the transmission in advance if necessary. The set gear change target is set, and the gear position of the transmission is maintained when gear change is not necessary. In other words, when the engine is stopped with the transmission set to the high-speed running state, and then the transmission is automatically decelerated when the engine is restarted within a predetermined time , the transmission is set to the low-speed running state. Engine is stopped for a certain period of time
It is to be made possible to maintain the speed position of the transmission upon restarting the engine within. And the engine stopped
When the stop operation is performed, the gear position of the transmission is controlled by the control means.
Even if the selection to maintain
By setting the parking brake to the braking state,
Is a predetermined time after the engine stop operation,
Since the control means changes the setting of the transmission to the neutral position,
After the engine is started, the vehicle body can be kept in a stopped state.
It

According to the fourth feature, even if the engine is stopped while the transmission is set to the high speed running state, the control target of the transmission is set to the lowest speed , so that the engine is automatically started when the engine is started. A gear change operation is performed and driving at the lowest speed
Because it does, there is no sudden start.

According to the fifth feature, when the engine is stopped while the transmission is in the medium speed range or the low speed range, the gear position is changed even after the engine is started. Since it is maintained, it becomes possible to start traveling at the set speed without suddenly starting.

[Effects of the Invention] Therefore, the engine is started within a predetermined time after the operation of stopping the engine.
When restarting and starting traveling, it is possible to automatically perform an appropriate gear shift operation without performing an operation that bothers the operator.
And the parking brake within a predetermined time after the engine is stopped.
When the brake is set to the braking state or the engine is stopped
After a predetermined time has passed, the vehicle will automatically be stopped.
After starting the engine by switching to the state (neutral position)
To avoid the phenomenon that the work vehicle runs at an unconscious speed
(Claims 1 to 3) Also, the transmission runs at high speed.
Even if the engine is stopped with the state set,
Prevents sudden start after engine restart within a predetermined time
It becomes an accident (Claim 4), and the engine is stopped before starting work.
Even if the engine is interrupted, start the engine within a predetermined time after stopping the engine.
If restarted, suitable for work before shutting down the engine
It is now possible to start traveling in the changed gear state (Claims)
5).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, an engine E is mounted on the front portion of a vehicle body having a drive-type front wheel 1 and a drive-type rear wheel 2 that are freely steerable, and the power from the engine E is A mission case 4 transmitted via the main clutch 3 is arranged at the rear part of the vehicle body, and a pair of left and right lift arms 5 driven and moved up and down by a hydraulic cylinder (not shown) are provided at the upper rear end position of the mission case 4. In addition, an operating unit is arranged in the center of the vehicle body to form an agricultural tractor as an example of a work vehicle.

As shown in FIGS. 1 and 2, a driver's seat 6 is provided in the driver's seat, a steering handle 7 is arranged in front of the driver's seat 6, and a front and rear direction is provided in the vicinity of the steering handle 7. A forward / reverse switching lever 8 which can be rocked is arranged, a position lever 9 for controlling the rocking angle of the lift arm 5 is arranged on the right side of the driver's seat 6, and a traveling speed is set on the left side of the driver's seat 6. A gear shift lever 10 (an example of a gear shift operation tool) is arranged. or,
A clutch pedal 11 for disengaging the main clutch 3 by depressing is arranged on the left side of the step, and a side brake pedal for independently braking the left and right rear wheels 2, 2 by depressing on the right side of the step. 12 and 12 are arranged.

As shown in FIG. 3, a lever guide 13 for guiding the speed change lever 10 has a main guide portion 13A whose longitudinal direction is formed along the front-rear direction, and the main guide portion 13A.
The main guide portion 13A is branched from an intermediate neutral position N to form a parallel sub guide portion 13B, and an overdrive speed change range OD is arranged at the front end of the main guide portion 13A. A parking position P for braking a parking brake (described later) is arranged, a standard shift range ST is arranged at the rear end of the auxiliary guide portion 13B, and a creep shift range CR is provided at the front end of the auxiliary guide portion 13B. Has been placed. Also, overdrive speed range OD, standard speed range S
T and the creep shift range CR each have an operation range in which the shift lever 10 can be slightly operated in the front-rear direction. When the shift lever 10 is set in each of the operation ranges, the center of the operation range in the front-rear direction is set. When the gear shift lever 10 is held at the holding position n of the gear shift lever 10 and the gear shift lever 10 is operated forward from the hold position n, the speed increasing switch SwU detects the operation of the gear shift lever 10 and the gear shift lever 10 moves from the holding position n. When the gear is operated backward, the deceleration switch SwD moves the gearshift lever 1
The shift lever 10 is configured to detect a zero operation.
Parking switch S that detects that the vehicle has been set to the parking position P
It has wP.

As shown in FIGS. 4 and 5, the shift lever 1
A fork-shaped member 14 having a bifurcated shape is provided at the base end portion of 0, and the fork-shaped member 14 is fitted to a laterally rotating shaft 15 and is swingably supported around a support shaft 16 in a front-back direction. A helical spring 17 is provided for urging the speed change lever 10 around the support shaft 16 from the main guide portion 13A side to the side where the sub guide portion 13B is formed. Further, a fan-shaped cam member 18 is provided on the vehicle body side, and the overdrive shift range OD and the creep shift range C are provided with respect to the cam member 18.
R, the neutral position N, the standard shift range ST, and the recessed portion 18A corresponding to the parking position P are formed, and the roller 20 that is engaged by the biasing force of the spring 19 in each recessed portion is swingable with respect to the shift lever 10. By equipping the swing end of the arm 21 supported by the gear shift lever 10, the shift lever 10 can be held at the holding positions n of the overdrive shift range OD, the standard shift range ST, and the creep shift range CR, respectively, and the neutral position N and the parking position P can be maintained. An urging mechanism F capable of urging and holding is constructed, and further, a potentiometer-type lever sensor LS for discriminating the operation position of the shift lever 10 from the rotation amount of the rotation shaft 15 is provided.
In addition, overdrive speed range OD, creep speed range C
In each of the R range and the standard shift range ST, the concave portion 18A is configured to have a gentle inclination so that the speed increasing switch SwU and the deceleration switch SwD can be operated by the speed change lever 10.

As shown in FIG. 6, the first arm 23 provided on the rotary shaft 15 and the operation arm 24 for creep speed change are connected via the first rod 25, and the second arm provided on the rotary shaft 15 is connected. Arm 26 and operation arm 2 for overdrive shifting
7 is linked via a pair of second rods 28, 28 and a swingable intermediate arm 29 to a third shaft provided on the rotary shaft 15.
A parking brake is linked via the arm 30 and the operation wire 31. This parking brake, as shown in Figure 7,
A lock member 33 having an engaging portion 33A configured to project into the mission case by the urging force of the compression spring 32 against the side wall of the mission case 4 and engage with the gear G of the traveling system in the mission case is provided. An operating piece 34, which comes into contact with the flange portion 33B on the outer end side of the lock member 33 to operate the lock member 33 in the engagement releasing direction, is swingably provided around the support shaft 35. The operation wire 31 is connected to the end of the switching arm 36 for operating the.
When the shift lever 10 is set in the shift range, the lock member 33 is set to the non-engagement position (non-braking state / off) by the operating force from the operation wire 31, and the shift lever 10 is set to the parking position P. In this case, the operation wire 31 is relaxed and the biasing force of the compression spring 32 sets the lock member 33 to the position (braking position / on) at which the lock member 33 engages with the gear G. As a result, the front and rear wheels 1 and 2 are held in a locked state. It has become a thing.

As shown in FIG. 6, when the speed change lever 10 is set to the overdrive speed change range OD, the overdrive speed change mechanism Tod (described later) is set and the creep speed change mechanism Tcr (described later) is set at the same time. Although the third transmission mechanism T3 (described later), which is arranged on the transmission side of the creep transmission mechanism Tcr, is set to the neutral position, the power from the overdrive transmission mechanism Tod is transmitted to the traveling system. It has become a thing. or ,
When the speed change lever 10 is set to the creep speed change range CR, the overdrive speed change mechanism Tod is set to the off state and at the same time the third speed change mechanism is set to the transmission state, whereby the power from the creep speed change mechanism Tcr travels. It has been passed down to the system. Further, when the speed change lever 10 is set to the neutral position N, the overdrive speed change mechanism Tod
And the creep speed change mechanism Tcr are both held in the neutral position so that power cannot be transmitted to the traveling system.
Further, when the speed change lever 10 is set in the standard speed change range ST, the mechanical linkage is formed so that the creep speed change mechanism Tcr is set to the standard position while the overdrive speed change mechanism Tod is set to be off.

Inside the mission case 4, a transmission system shown in FIG. 8 is installed. That is, the engine E
A first speed change mechanism T1 provided with four sets of gears and two sets of synchromesh type shift members 41 and 42 for changing the power transmitted from the main clutch 3 to four stages.
A hydraulic clutch C arranged under the transmission of the first speed change mechanism T1, two sets of gears arranged under the transmission of the hydraulic clutch C and one synchromesh type shift member 43 for shifting the power in two steps. Second auxiliary transmission mechanism T including
2. A forward / reverse speed change mechanism Tfr provided with a reverse gear system and a synchromesh type shift member 44 for transmitting the power of the second speed change mechanism T2 in a forward rotation state and a reverse rotation state. A third speed mechanism T provided with two sets of gears and one synchromesh type shift member 45 arranged to lower the power transmission of the mechanism Tfr to shift the power in two stages.
3. An overdrive transmission mechanism Tod and a third transmission mechanism T3, which include a pair of gear systems arranged under the transmission for obtaining a high speed shift state and a synchromesh type shift member 46.
And a creep speed change mechanism Tcr provided with a set of gears that greatly reduce the speed and a constant mesh type shift member 47 and a state in which the speed change state from the third speed change mechanism T3 is directly transmitted. Then, the power from this speed change system is transmitted to the rear wheels 2 through the differential device 48 for the rear wheels 2, and the peripheral speed of the front wheels 1 is matched with the peripheral speed of the rear wheels 2 to drive the standard drive state. To the front wheels 1 via the front wheel speed increasing device 49 and the front wheel drive shaft 50, which are switchable between a front wheel speed increasing device 49 and a front wheel drive shaft 50 that can be switched to a speed increasing drive state in which the peripheral speed of the front wheels 1 is made higher than that of the rear wheels 2. The traveling transmission system is configured so that Incidentally, this front wheel speed increasing device 4
An operation system is formed so that the front wheel 1 can be switched to a speed-up drive state when the front wheel 1 is operated to be larger than a preset steering angle. It is designed to reduce the radius.

Further, the main transmission device TM for shifting the forward traveling speed to eight stages by the first transmission mechanism T1 and the second transmission mechanism T2.
The main transmission device TM includes a first hydraulic cylinder P for operating three shift members 41, 42, 43, respectively.
1, a second hydraulic cylinder P2, and a third hydraulic cylinder P3 (an example of an actuator), the shift member 44 of the forward / reverse shift mechanism Tfr is mechanically linked to the forward / reverse switching lever 8, and is connected to the third shift mechanism T3. Includes a fourth hydraulic cylinder P4 (an example of an actuator) for operating the shift member 45, and the shift member 46 of the overdrive transmission mechanism Tod.
Is linked to the operation arm 27 for the overdrive shift, and the shift member 47 of the creep transmission mechanism Tcr is linked to the operation arm 24 for the creep shift.

As shown in FIG. 9, a hydraulic system for controlling the hydraulic cylinders and the hydraulic clutch C is constructed. That is, the first, second and fourth hydraulic cylinders P1,
P2 and P4 are configured as a double-acting type in which the shift members 41, 42 and 45 can be set to both operation ends and the neutral position (a structure similar to that shown in the prior art including the publication number). The hydraulic cylinder P3 is of a double-acting type in which the shift member 43 can be set at both operation ends.
The hydraulic oil from the hydraulic pump 51 driven by the engine E is supplied to seven electromagnetically operated cylinder control valves V1, V1, V2, V2, V3, V4, V4 for controlling P2, P3, P4. An oil passage system is formed, an oil passage system for supplying hydraulic oil from the hydraulic pump 51 to the hydraulic clutch C via a pilot operated on-off valve Vc is formed, and an electromagnetic proportional pressure is also formed. The control valve Vp forms an oil passage system that adjusts the pressure when the hydraulic clutch C is engaged, and an oil passage system that supplies hydraulic oil to the pilot oil passage 53 through the orifice 52. Furthermore, a system is provided which forms an oil passage for operating the on-off valve Vc by the pressure of the pilot oil passage 53, and lowers the pressure with respect to the pilot oil passage 53 via five check valves 54. There is. Four of the five check valves 54 ... Are mechanically opened / closed when the hydraulic cylinders P1, P2, P3, P4 are operated, and one check valve 54 is left.
Is linked so as to be opened and closed when the forward / reverse switching lever 8 is operated, and a pressure sensor 55 is provided in the pilot oil passage 53.

The hydraulic cylinders P1, P2, P3
At the start of the operation of P4, the corresponding check valve 54 is opened to reduce the pressure in the pilot oil passage 53, thereby switching the on-off valve Vc to the drain position and disengaging the hydraulic clutch C. The gear shift is performed by the operation of the hydraulic cylinder at the timing when the hydraulic clutch C is in the disengaged state. After that, when the operation of the hydraulic cylinder is completed, the check valve 54 is returned to the closed state. As a result, the on-off valve Vc is operated to the hydraulic oil supply position, and the hydraulic oil supplied thereby is adjusted in pressure by the control valve Vp. The hydraulic clutch C is sent to the hydraulic clutch C and reaches the engaged state, so that it is not necessary to artificially disengage the main clutch 3 during a gear shift. Similarly, when the forward / reverse switching lever 8 is operated, the corresponding check valve 54 opens to open the pilot oil passage 5
By changing the pressure of No. 3, the on-off valve Vc is switched to the drain position and the hydraulic clutch C is disengaged to perform gear shifting, and then the check valve 54 is closed at the end of the operation of the forward / reverse switching lever 8. As a result of the return, the on-off valve Vc is operated to the hydraulic oil supply position, the hydraulic oil supplied thereby is sent to the hydraulic clutch C while the pressure is adjusted by the control valve Vp, and the hydraulic clutch C is put in the on state. Has reached. Further, when the shift operation is performed in this way, the pressure in the pilot oil passage 53 decreases and then rises. When this pressure change is detected by the pressure sensor 55, a control device (described later) controls By adjusting the current to the electromagnetic solenoid of the valve Vp, the supply pressure of the hydraulic oil supplied to the hydraulic clutch C is adjusted according to the predetermined characteristics to increase the pressure of the hydraulic clutch C, and the smooth entry is achieved without causing a shock. It is supposed to switch to the state.

As described above, at the time when the hydraulic cylinder starts to operate, the hydraulic pressure immediately before the operation of the shift member starts due to the mechanical gap between the members linked to the hydraulic cylinder and the elastic strain of the shift system. The clutch C can be switched to the disengaged state.
By operating the shift member with the hydraulic cylinder in the state of turning off the gear, gear shifting can be performed without manually manipulating the main clutch 3. Further, when the gear shifting by the shift member is completed, the hydraulic clutch C By returning to the ON state, the shift power can be transmitted.

As shown in FIG. 10, a control device 61 (an example of control means) equipped with a microprocessor is used to start and stop the engine E, and to supply and stop electric power to electric devices provided on the vehicle body. The key switch 62, the pressure sensor 55, the three speed increasing switches SwU, 3
Signals from the two deceleration switches SwD, the parking switch SwP, the lever sensor LS, the forward / backward movement sensor 63 for detecting the operating position of the forward / backward movement switching lever 8, and the main clutch sensor 64 for determining the state of the main clutch 3. To form a system for inputting the
1, V1, V2, V2, V3, V4, V4, the pressure control valve Vp, and a system for outputting a control signal to the speed change display device D arranged on the meter panel in front of the driver's seat 6. Formed, and further, an EEPROM type memory 65
A signal system for inputting and outputting data to and from is formed.

As shown in the figure, the speed change display device D is a letter "F" indicating that the light emitting diode type display 66 for displaying the number of the shift speed and the forward / reverse switching mechanism Tfr are set to the forward drive state. The forward lamp 67 indicated by, the reverse lamp 68 indicating by the letter "R" that the forward / reverse switching mechanism Tfr is set in the reverse state, and the shift lever 10.
Is set to the neutral position N, and the two hydraulic cylinders P1 and P2 of the main transmission device TM and the hydraulic cylinder P4 of the third transmission mechanism T3 are set to the neutral position. The neutral lamp 69 indicated by the letter "N", the parking lamp 70 indicating that the gearshift lever 10 is set to the parking position P by the letter "P", and the overdrive transmission mechanism Tod being in the transmission state. Overdrive lamp 71 indicated by the letters "Overdrive"
And a standard lamp 72 that indicates that the creep transmission mechanism Tcr is in the standard transmission state by the character "standard", and a creep ramp 73 that indicates that the creep transmission mechanism Tcr is in the transmission state by the character "creep". The shift control by the control device 61 will be described below.

As shown in the flow chart of FIG. 11, when the key switch 62 is turned on to start the engine E and the control is started, the data stored in the memory 65 is set as the gear shift target, and then the gear shift control is performed. , The key switch 62 turns off the display operation for displaying the shift state on the shift display device D.
It is performed continuously until F is operated (# 1
01, # 200, # 102, # 103 steps). This shift control is a control for accelerating and decelerating the main transmission device TM based on the operation of the shift lever 10. In the display operation, the overdrive lamp 7 is set based on the setting state of the shift lever 10.
1, the standard lamp 72, or the creep lamp 73 is turned on, the gear stage set in the main transmission TM is displayed on the display 66, and when the gear shift lever 10 is set to the neutral position N, the neutral position is set. The control for turning on the lamp 69 and turning on the forward lamp 67 or the backward lamp 68 is performed based on the set position of the forward / reverse switching mechanism Tfr.

After the key switch 62 is turned off and the engine E is stopped, the gear shift lever 10 is moved to the overdrive range O based on the signal from the lever sensor LS.
When it is in D, the speed change target of the main transmission TM is written in the memory 65 so as to be set to the first speed, and the speed change lever 10 is in the other range, that is, the standard speed change range ST or the creep speed change range CR. Is written in the memory 65 (steps # 104 to # 106) so as to set the current gear stage of the current main transmission device TM as the gear shift target, and the timer (which is composed of software) is activated. When the key switch 62 is turned on before the time set by the timer 62 (time of several minutes to about 30 minutes) elapses, the shift stage based on the data written in the memory 65 is set as the shift target. The shift control is performed as described above, and when the key switch 62 is not turned on and the time set in the timer has elapsed, or the shift lever 10 is parked. If it is operated in the location P has become used to set the transmission target to the neutral position (# 1
07- # 111 steps).

Then, the engine E is stopped while the work is being performed while the speed change lever 10 is set to the standard range ST or the creep range CR, and the work is temporarily interrupted, and the engine E is not used until a short time elapses. When the gear is started and the work is restarted, the gear position is maintained.
It becomes possible to run at a speed suitable for the work without operating 0, and as in the case where the engine E is stopped when the target point is reached on the road running in the overdrive speed change state, In a situation where high-speed traveling is not required after the start of E, the main transmission T
By forcibly setting M to the lowest speed, if the engine E is started before the time elapses, low speed traveling is performed, and if the time elapses, traveling is stopped. There is.

The control operation of the shift control routine (step # 200) is configured as shown in the flowchart of FIG. 12, and in this control, it is determined that the forward / reverse switching mechanism Tfr is at a position other than neutral, and the forward / reverse sensor is used. Detected at 63,
Also, the lever sensor LS detects that the creep transmission mechanism Tfr is not in the creeping transmission state, and the main clutch sensor 64 indicates that the main clutch 3 is in the engaged state.
When it is detected in (steps # 201 to # 203),
When the speed increasing switch SwU is turned on, the shift target is increased by one step, and when the deceleration switch SwD is turned on, the shift target is decreased by one step, and the main transmission device TM and the third speed change gear are set to obtain this shift target. Hydraulic cylinder P1, with mechanism T3
P2 and P4 are operated (sequential shift mode, steps # 204 to # 208). When the forward / reverse traveling sensor 63 detects that the forward / reverse traveling switching mechanism Tfr is in the neutral position, or when the lever sensor LS detects that the creep transmission mechanism Tcr is in the creeping transmission state, the main clutch 3 is disengaged. When the main clutch sensor 64 detects that the vehicle is in the state (steps # 201 to # 203), when the speed increasing switch SwU is turned on, the ON time continues for a predetermined interval (shorter than 1 second). Each time), the shift target is increased by one stage, and conversely, when the deceleration switch SwD is turned on, the shift target is set at a predetermined interval (short time of 1 second or less) within the duration of the ON time. The gears are reduced one by one, and the gears are shifted by operating the hydraulic cylinders P1, P2, P4 of either the main transmission device TM or the third transmission mechanism T3 so as to obtain this shift target. Cormorants control mode is set (continuous transmission mode, #
209 to # 212 step, # 208 step).

Further, in this shift control, by operating the shift lever 10 in the standard shift range ST, the main shift device TM and the third shift device can be operated.
Combined with the speed change mechanism T3, 16 speeds are possible,
By shifting the shift lever 10 in the overdrive shift range OD, it is possible to shift gears in eight steps in the same manner.
Similarly, by shifting 0 in the creep shift range CR, 16 shifts are possible (only the 8th shift of the main transmission device TM may be shifted). Further, when the shift lever 10 is operated in the standard shift range ST, the standard lamp 72 lights up and at the same time, the shift stage is displayed on the display 66, and when the shift lever 10 is operated in the overdrive shift range OD, the overdrive lamp is displayed. 71 is turned on, the gear is displayed on the display 66 at the same time, and the gear shift lever 10
When is operated in the creep shift range CR, the gear position is displayed on the display 66 at the same time when the creep pump 73 is turned on.

As described above, according to the present invention, when the engine is stopped during traveling at the traveling speed used for work, or when an engine stop occurs, the engine E is started within a short time. By doing so, it is possible to run at the gear stage before the engine is stopped,
In addition, when the engine E is started after the engine E is stopped during high speed running using the overdrive speed change mechanism Tod or low speed running using the creep speed change mechanism Tcr, an appropriate speed change is automatically performed. At the same time, the annoyance of manually changing gears is eliminated, and at the same time, sudden start and inefficient low speed running can be avoided.

[Other Embodiments] In addition to the above-described embodiments, the present invention includes, for example, a dedicated operation tool for shifting the overdrive transmission mechanism or a dedicated operation tool for shifting the creep transmission mechanism. It is possible to implement it as it is provided, or it is also possible to implement it in a structure without an overdrive transmission mechanism.

Further, according to the present invention, when a gear shift lever is set in the overdrive range or the creep range and a gear shift operation is performed, a part of the gear shift is performed instead of the control for shifting in the entire gear shift range of the transmission. Shift in the range, or an odd number of steps,
It is also possible to reduce the number of gears by performing gear shifting only at even gears.

[Brief description of drawings]

1] Overall side view of an agricultural tractor

FIG. 2 is a plan view of the rear part of the agricultural tractor.

FIG. 3 is a plan view of a lever guide.

FIG. 4 is a side view of a gear shift lever support structure.

FIG. 5 is a front view of a gear shift lever support structure.

FIG. 6 is a side view showing the linkage of shift levers.

FIG. 7 is a vertical sectional view showing a parking brake.

FIG. 8 is a schematic diagram of a traveling transmission system.

FIG. 9 is a hydraulic circuit diagram for traveling speed change.

FIG. 10 is a block circuit diagram of a control system.

FIG. 11 is a flowchart of main control operation.

FIG. 12 is a flowchart of a shift control routine.

[Explanation of symbols]

One and two wheels 10 Gear change operation tool 61 control means E engine

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B60K 41/04 B60K 41/04 F02D 29/02 321 F02D 29/02 321B (56) Reference JP-A-8-210498 (JP, JP, A) JP 62-175228 (JP, A) JP 6-50420 (JP, A) JP 58-94659 (JP, A) JP 8-233101 (JP, A) JP 59 -121241 (JP, A) JP-A-7-2676 (JP, A) JP-A-9-240297 (JP, A) JP-A-9-79374 (JP, A) JP-A-3-504837 (JP, A) ) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H 61/26-61/36 F16H 63/00-63/38 B60K 17/00-17/08 B60K 20/02-20/08 B60K 41/00-41/28 F02D 29/02

Claims (5)

(57) [Claims] 1. A control for operating a actuator (P3) based on an operation of a gear shift operation tool (10) and gear-shifting a transmission (TM) by a driving force of the actuator (P3) to obtain a predetermined gear stage. A work vehicle including a means (61), wherein a state in which a gear position of a transmission (TM) is maintained based on a stop operation of an engine (E) provided on a vehicle body, and a state of transmission (T
The control mode of the control means (61) is set so as to select either the state in which M) is set to a preset gear shift target, and at a predetermined time after the operation of stopping the engine (E).
Parking brake without restarting the engine (E)
When set to the braking state, or when the engine (E) is stopped
When the predetermined time has elapsed after the stop operation, the selected speed change
Power is not transmitted to the wheels (1) and (2) from the control state
The control means for switching the standing position (N) to the gear shift target.
A work vehicle in which the control form of (61) is changed . 2. An operation based on an operation of a gear shift operation tool (10).
Actuating the actuator (P3), this actuator
Change the speed of the transmission (TM) with the driving force of (P3).
A work vehicle provided with a control means (61) for obtaining a constant gear position.
Shifts based on the stopping operation of the engine (E) equipped on the vehicle body.
Of the transmission (TM) and the transmission (T
M) is set to a preset shift target
The control mode of the control means (61) is set so as to select
At a predetermined time after engine (E) stop operation
If the engine (E) is restarted within the interval, select the above
The gear is set to the changed gear state and the engine (E) is stopped.
Park without restarting the engine (E) within a predetermined time after operation
When the car brake is set to the braking state or when the engine
If a predetermined time has elapsed after the stop operation of the
The power is applied to the wheels (1) and (2) from the control mode of the changed gear shift state.
Before switching the neutral position (N) that does not transmit the
Note that the control mode of the control means (61) is changed.
A featured work vehicle. 3. Based on the operation of the gear shift operation tool (10),
Actuating the actuator (P3), this actuator
Change the speed of the transmission (TM) with the driving force of (P3).
A work vehicle provided with a control means (61) for obtaining a constant gear position.
Shifts based on the stopping operation of the engine (E) equipped on the vehicle body.
Of the transmission (TM) and the transmission (T
M) is set to a preset shift target
The control mode of the control means (61) is set so as to select
At a predetermined time after engine (E) stop operation
If the engine (E) is not restarted within the
If the rake is not set to the braking state,
If the speed of the wheel is exceeded,
(1) Shift the neutral position (N) where power is not transmitted to (2)
The control mode of the control means (61) is set to switch to the target.
A work vehicle that is subject to constant changes . 4. The shift target selected when the engine (E) is stopped while the transmission (TM) is set to a high-speed running state is the lowest speed.
The work vehicle according to any one of Items 1 to 3 . 5. The transmission (TM) is configured to be capable of shifting in any one of a high speed range, a medium speed range and a low speed range, and the transmission (TM) has a middle speed range and a low speed range. When the engine (E) is stopped while the gear is being operated in any of the ranges, the control means (6) maintains the shift speed at the time of the engine stop operation.
4. The control method according to claim 1), wherein the control mode is set.
The work vehicle described there .