JP2536369B2 - Front wheel rotation drive controller for four-wheel drive type mobile 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 front wheel rotation drive control device for a four-wheel drive type mobile vehicle.

[0002]

2. Description of the Related Art As conventional techniques, a four-wheel drive vehicle is a two-wheel drive during turning in which the front wheels are turned off and the two rear wheels are turned during turning, and the average peripheral speed of the front wheels is determined by the rear wheels during this turning. On the other hand, there is a four-wheel-drive speed-increasing four-wheel drive system that makes a turn by accelerating about twice as fast.

[0003]

Such a conventional one merely performs mechanical control in accordance with the standard operating sequence set at the beginning, and ignores any change in the ground condition. And standard operation is performed. Such a conventional one is not problematic when traveling on the ground in a standard condition, but if the standard operation is performed during straight traveling or turning traveling on muddy ground or uneven road surface, the traveling performance deteriorates. It may happen that you cannot drive.

That is, when the vehicle is simply switched to rear two-wheel drive during a turn, if one of the rear wheels slips on muddy ground,
If the vehicle cannot move forward due to the function of the differential device at the center of the rear wheels, or if the turning point goes downhill on an uneven road surface and the rear wheels slip, only the rear wheels will support the weight of the vehicle and the engine brakes Does not act, and the car body may run away to the lowland.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem of the conventional apparatus, and has taken the following technical means. That is, engine 1
Is transmitted to the rear wheels 3 and the front wheels 4 via the transmission mechanism 2 of a plurality of stages, and in the four-wheel drive type mobile vehicle in which the front wheels 4 side is the steering wheel, the transmission mechanism between the transmission mechanism 2 and the rear wheels 3 is A direct coupling clutch 7 that connects the rotation of the rear wheel drive rotating shaft 5 to the front wheel 4 through the front drive shaft 6 and connects / disconnects the rotation of the rear wheel drive rotating shaft 5 to / from the front drive shaft 6 at the same rotation ratio. And a rear axle rotation sensor 9 for detecting the number of revolutions of the rear wheel drive rotary shaft 5 by providing the front drive shaft 6 with a speed increasing clutch 8 for accelerating and turning on / off the rotation of the rear wheel drive rotary shaft 5.
Front shaft rotation sensor 10 for detecting the rotation speed of the front drive shaft 6
And a steering angle sensor 11 for measuring the steering angle of the front wheels 4.
When the direct coupling clutch 7 or the speed increasing clutch 8 is turned on by the detection values of these sensors 9, 10, 11 when these are provided, the clutches 7, 8 are turned on for a short time thereafter.
As the FF, the values of the sensors 9, 10, 11 are detected to measure the road surface condition, and the direct coupling clutch 7 or the speed increasing clutch 8 is used.
A front wheel rotation drive control device for a four-wheel drive type mobile vehicle is provided with a control means 13 for determining whether or not ON operation is required.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. The illustrated example is an agricultural tractor 14, and the front wheels 4, 4 drive section of the agricultural tractor 14 are
This is an inset of the present invention. Agricultural tractor 14
The front-rear four-wheel drive type mobile vehicle is equipped with front-rear wheels 4, 4, 3, 3 at four front-rear corners of the vehicle body.
It is driven using the power of.

The front and rear wheels 4, 4, 3 and 3 are connected to front and rear axle cases 15 and 16, respectively, and project outwardly, and their base ends are a front frame 17 and a gear case which is a main frame. It is attached to 18, etc. The rear end of the front frame 17 is a machine frame integrally attached to the main frame side,
The engine 1 is detachably attached to a front portion of a front frame 17 which is a machine frame.

The central portion of the front axle case 15 in the left-right direction is pivotally attached 19 to the front frame 17 so that the front wheels 4 can move up and down due to the unevenness of the ground. A front differential device 20 that adjusts the peripheral speed difference between the left and right front wheels 4 and 4 is provided in the center of the front axle case 15 in the left-right direction, and the front drive device 21 projects outside from a transmission case 21 to be described later. It is input via the axis 6.

A radiator 22 and a cooling fan 23 are arranged in front of the engine 1. Reference numeral 12 denotes an engine rotation sensor, which is provided in the vicinity of the cooling fan 23 in the illustrated example to measure the rotation speed of the engine 1 and transmit it to the controller 13 which is the control means. For example, the rotation of a crankshaft (not shown) and other rotating parts may be detected.

A hood 24 covers the front and side of the engine 1 and auxiliary devices (not shown). Reference numeral 26 denotes a clutch housing, which is attached to the rear portion of the engine 1 and internally houses a main clutch 27, and transmits a driving force to a rear transmission case 21 portion.

Reference numeral 28 is a handle, and 29 is a handle post. The lower end of the handle post 29 is attached to the machine frame, and when the handle 28 is rotated left and right, the front wheels 4 and 4 are steered left and right. And this front wheel 4,
Read the left and right steering angle of 4 with the steering angle sensor 11,
It is transmitted to the controller 13.

Fenders 30, 30 are attached from the front of the left and right rear wheels 3, 3 to the upper side, and a seat 31 is provided between the left and right fenders 30, 30. The left and right rear wheels 3, 3 are connected left and right by a rear axle case 16, and a rear differential device 25 is provided in the middle portion between the left and right. Gear case 1 that houses the rear differential device 25
8 is attached to the rear portion of the transmission case 21 described above, and the transmission case 21 is integrally connected to the rear end portion of the clutch housing 26.

From the driver's feet below the seat 31 to both sides below the handle post 29, a substantially flat floor 3 is provided.
2 is attached. The floor 32 is substantially flat in the left-right direction and has an outer width that is close to the outer edge portions of the left and right fenders 30, 30, that is, a width close to the entire width of the body. Engine 1
The driving force from the main clutch 27 is input from the front part of the transmission case 21.

Although not shown in detail, the input driving force reaches the rear differential device 25 through the transmission mechanism 2 including a reverser device 33 for performing forward and backward shifting, a main transmission device 34, an auxiliary transmission device 35, and the like. Drive system,
It is divided into two systems, that is, a PTO drive system 36 which is an external power take-off that is branched at the entrance of the transmission case 21. A PTO shaft 37 projects rearward from the gear case 18, and a universal joint (not shown) for driving various working machines is detachably attached to the PTO shaft 37.

The output shafts 75, 75 are projected left and right from the rear differential device 25, and the left and right rear wheels 3, 3 are attached to the rear of the transmission path provided with the left and right brakes 76, 76 in the middle of the output shaft 75. . These left and right rear wheels 3,
Although not shown, 3 is independently or simultaneously braked by independent left and right brake petals.

Any drive shaft may be used as long as it is output from the transmission mechanism 2 and input to the rear differential device 25.
The driving force of the rear wheel driving rotary shaft 5 which is this driving shaft is transmitted to the main gear 40 via the output gear 38 and the counter gear 39. The main gear 40 is engaged with the spline portion of the first clutch boss 41 and rotates integrally with the first clutch boss 41.

Further, another sub gear 42 is attached by engaging with this spline portion, and the main and sub gears 40, 42 rotate simultaneously. These are two gears in the example,
If there is no problem in the number of teeth, the main and sub gears 40, 42 may be one. The sub gear 42 has a counter inlet gear 43.
, And the counter outlet gear 45 connected by the connecting drive shaft 44 is also integrally rotatable.

The counter outlet gear 45 is always meshed with the second clutch gear 46, and the second clutch gear 46 and the second clutch boss 47 integral with the second clutch gear 46 can be simultaneously rotated. In other words, when the main gear 40 rotates, the first clutch boss 41 and the second clutch boss 47, which are provided on the front drive clutch shaft 48 so as to face each other and rotate freely, rotate at the same time, and when the main gear 40 stops, the first clutch boss 41 and the second clutch boss 47 rotate. The first and second clutch bosses 41 and 47 stop at the same time.

The counter inlet gear 43 is accelerated by the auxiliary gear 42, and the second clutch gear 46 is accelerated by the counter outlet gear 45. When the first clutch boss 41 makes one revolution, the second clutch boss 47 is rotated. Rotates about twice. The first and second clutch bosses 41, 4
A first piston 49 and a second piston 50 are arranged between 7 and the outer circumference is covered with a drive drum 52 having a plurality of friction plates 51, 51 therein.

The drive drum 52 is divided into front and rear by a partition wall 53, and the rear first clutch boss 41 and the friction plate 5 are provided.
1 and the first piston 49 constitute the direct coupling clutch 7, and the front second clutch boss 47, the friction plate 51 and the second piston 5
0 constitutes the speed increasing clutch 8. Drive drum 52
Are integrally assembled to the spline portion of the front drive clutch shaft 48.

Lubricating oil 54 is held in the transmission case 21 to lubricate each transmission gear and shafts. This lubricating oil 54
A part of the oil is sucked and pressurized by the oil pump 55, and the first oil chamber 56 between the first piston 49 and the partition wall 53 of the direct coupling clutch 7 or the speed increasing clutch is provided via the oil passage switching valve 58. The second oil chamber 57 portion between the second piston 50 and the partition wall 53 of No. 8 is supplied.

The oil passage switching valve 58 shown in FIG. 2 is in a neutral state. In this neutral state, both the direct coupling clutch 7 and the speed increasing clutch 8 are in the OFF state. Next, when the first solenoid 59 is energized, the oil passage switching valve 58 switches to the valve 58a portion, the high pressure oil flows into the first oil chamber 56, the direct coupling clutch 7 is engaged, and the rotation of the rear wheel drive rotary shaft 5 is directly forwarded. Transmission to the drive clutch shaft 48.

When the second solenoid 60 is energized, the oil passage switching valve 58 is switched to the valve 58b so that the high pressure oil is supplied to the second oil chamber 5
7, the speed increasing clutch 8 is connected, and the rotation of the rear wheel drive rotary shaft 5 is almost doubled and transmitted to the front drive clutch shaft 48. The rotation of the rear wheel drive rotary shaft 5 input to the front drive clutch shaft 48 is linked to the front drive shaft 6 described above, and drives the front wheels 4 and 4 via the front differential device 20.

As described above, the rotation of the front drive shaft 6 when the direct coupling clutch 7 is ON and the speed increasing clutch 8 is OFF is described below. The rotation of the front drive shaft 6 is substantially constant with respect to the rear wheel drive rotating shaft 5. When the direct drive clutch 7 is OFF and the speed increasing clutch 8 is ON, the rotation of the front drive shaft 6 is approximately double that of the rear wheel drive rotary shaft 5 when driven in the first "front and rear four-wheel drive state H". The front drive shaft 6 is driven in the second "front wheel speed-increasing four-wheel drive state D", which is the rotational peripheral speed of, and both the clutches 7 and 8 are in the OFF state. ", The front wheels 4 are simply in the rolling state. (The wheeled state means that the front wheels 4 are pulled and rotated when the machine body moves and stopped when the machine body is stopped.) 61 is a drain oil passage, and the oil passage switching valve 58 is switched. And the pressure oil in the oil chambers 56 and 57 of the clutches 7 and 8 escapes to the transmission case 21 which also serves as a hydraulic tank.

In the illustrated example, the transmission case 21 is used as an oil reservoir, but a separate oil tank may be provided for exclusive use. A rear shaft rotation sensor 9 is arranged near the counter outlet gear 45, and a front shaft rotation sensor 10 is arranged near the drive drum 52 to detect the number of rotations of each rotating portion and control means. To the controller 13.

The control operation of the agricultural tractor 14 of the present invention will be briefly described as follows. First, the rear wheel 3
While traveling in the "rear wheel two-wheel drive state C" in which only the steering wheel is driven, the steering angle of the steering wheel 28 is detected during this traveling.
If the detected angle is 1 and the set angle exceeds α, "turn control F"
Control is performed, and if not exceeded, control of "straight ahead control G" is performed.

The "turning control F" controls the "turn control I" at a large steering angle when all the conditions shown in FIG. 6 are satisfied, and at a small steering angle when a part of the conditions is denied. The control is changed to "Turn control II". The "turn control I" at the large steering angle of the "turning control F" will be described in detail later.

"Turn control II" at a small steering angle is shown in FIG.
As shown in, the agricultural tractor 14 traveling in the "rear wheel two-wheel drive state C" is "front-rear four-wheel drive state H" in which the rotation speeds of the front wheels 4 and the rear wheels 3 are forcibly fixed to substantially the same speed. When the 4WD flag that is “” is not turned on, the ground slip of the rear wheel 3 is detected, and if there is a lot of slip, the vehicle runs at 4WD,
It is a mode in which the vehicle travels at 2WD if the slip is small.

The "straight ahead control G" is divided into "slip control" or "brake control" depending on various conditions as shown in FIG. The "brake control" is such that when the rear wheel 3 of the agricultural tractor 14 running in the "rear wheel two-wheel drive state C" is braked, a change in the rotation of the front wheel 4 is detected by the front wheel rotation sensor 10, and the front wheel 4 is detected. Direct rotation clutch 7
The brake performance is improved by turning on to set to "front and rear four-wheel drive state H", that is, 4WD.

Next, the details of the control will be described in detail mainly with reference to the flow chart. First, whether the steering amount of the steering wheel 28 of the agricultural tractor 14 traveling in the “rear wheel two-wheel drive state C” exceeds or does not exceed the set angle “α” of the steering angle sensor 11 (probably 5 degrees). , "Turning control F" or "straight ahead control G" is shown in FIG. In this way, the control is divided into two large subroutines depending on the detection value of the steering angle sensor 11.

"Turning control F" which is one of the subroutines
As described above, if all of the following conditions are satisfied, the "turn control I" is controlled, and if a part of the conditions is denied, the "turn control II" is controlled. Described in. "Turning control F"
When is started, first of all, as an initial setting, the data in the “straight ahead control G” described later is initialized, that is, the first solenoid 5
9 and the second solenoid 60 are turned off to start traveling in the "rear wheel two-wheel drive state C" in which the driving force to the front wheels 4 and 4 is cut off.

Manually turning on / off It is judged whether or not the speed-increasing turning switch 64 is turned on.
It is determined whether or not the vehicle speed averaged on the left and right of the rear wheels 3 and 3 read by the rear axle rotation sensor 9 has reached the set vehicle speed "V" (about 4 Km / H), and the set vehicle speed "V" has not been reached. The steering angle of the front wheels 4 and 4 read by the steering angle sensor 11 exceeds γ (approximately 40 degrees to one side from the straight traveling state), and a working machine (not shown) attached to the end of the agricultural tractor 14 so as to be vertically movable. When the position lever 66 for operating the ascending / descending position of (1) is raised, the "turn control I" traveling in the "front wheel speed-increasing 4WD state D" is operated.

Further, the speed-increasing turning switch 64 that is manually turned on and off, which is the judgment of the condition of the "turn control I", is set to O.
In the case of FF, the vehicle speed averaged between the left and right rear wheels 3 and 3 read by the rear axle rotation sensor 9 is set vehicle speed "V" (4K
m / H), the steering angle of the front wheels 4 and 4 read by the steering angle sensor 11 does not reach γ (approximately 40 degrees from the straight traveling state to one side), and the end of the agricultural tractor 14 body Work unit (not shown) that can be mounted vertically on the unit
When the position lever 66 for operating the ascending / descending position is kept in the lowered position operation, and all or any of the conditions are satisfied, the "turn control II" is activated.

Next, the operation of the "turn control I" for traveling in the "front wheel speed-increasing 4WD state D" will be described with reference to the flowchart of FIG. First of all, it is judged whether the full turn flag, which is the "turn control I" flag, is ON. If not, it means that the vehicle is running in "rear wheel two-wheel drive state C". 10 and the detection values of the rear axle rotation sensor 9 are read, and the front wheels 4, 4 and the rear wheels 3, 3 are read.
It is determined whether or not there is a difference in the average peripheral speeds of the left and right wheel rotations of.

In other words, the front wheel rotation sensor 10 detects the moving speed of the machine body running in the "rear wheel two-wheel drive state C", and the rear wheel rotation sensor 9 detects the driving speed of the rear wheel 3 to rotate them. It is determined whether the front wheel 4 is overrun in the "rear wheel two-wheel drive state C" with respect to the rear wheel 3 by judging whether the peripheral speed difference is large or small. One of the preconditions is that when the "turn control I" is activated, the front wheels 4 and 4 are always in a steering turn because they exceed the steering angle γ, and the peripheral speed of each wheel is the turning radius. If the rear wheels 3 and 3 do not slip to the ground during driving due to the difference between the two, even if both the direct coupling clutch 7 and the speed increasing clutch 8 are in the OFF state, the front wheels 4 and 4 are pushed by the body due to the large turning radius. Therefore, it is judged that there is a front wheel overrun, and the next overrun rate is judged.

When the overrun rate of the front wheels 4 exceeds a predetermined value "B" (about 180% as an experimental value for the rear wheels), that is, the rear wheels 3 and 3 reliably transmit the driving force to the ground. The operation of the "turn control I" for driving the front wheels 4 to increase in speed is unnecessary, and the full turn flag is not turned on and the vehicle turns in the "rear wheel two-wheel drive state C". During this turning, when the rear wheel 3 slips to the ground due to the soft ground condition of the field and the force for pushing the vehicle body becomes weak, the "rear wheel two-wheel drive state C" of the front wheel 4 is generated.
The overrun rate at 1 does not reach the predetermined value "B", the full turn flag is turned on, and then the second solenoid 60 is turned on.
N, the pressure oil flows into the second oil chamber 57 on the speed increasing clutch 8 side, and the front wheels 4 are rotated at increased speed.

Here, even if there is a command for the control operation of the "front wheel speed-increasing 4WD state D" which is one of the main parts of the present invention,
The point of determining whether or not the control operation is necessary will be described. Even if the second solenoid 60 is turned on, there is usually a time lag of 0.4 to 0.5 seconds until the speed increasing clutch 8 that forcibly rotates the front wheels 4 approximately twice as much as the rear wheels 3 is actually operated.

When the time lag of 0.4 to 0.5 seconds elapses, the "front wheel speed-increasing 4WD state D" is set, and the overrun rate of the front wheel 4 is forced by the operation of the speed-increasing clutch 8 to a predetermined value "B". Since it is exceeded, it is determined whether it is during the next wait process 70. First, the first time is NO because the wait process is not being performed, and the number of changes in the count number of the next "2WD and full turn" is checked.

The number of changes in the count number of "2WD and full turn" means that the overrun rate of the front wheels 4 in the "rear wheel two-wheel drive state C" reaches a predetermined value "B" and the "rear wheel two The vehicle is driven in the driving state C "or the second solenoid 60 is turned on when the overrun rate of the front wheels 4 does not reach the predetermined value" B ".
N is the number of times the control is switched to the "front wheel speed-increasing 4WD state D", which is a full turn for operating the speed-increasing clutch 8 and the count number of one reciprocation is a predetermined constant "N". (Tentatively 3 times.) It is determined whether or not it has exceeded. At the first time, the count number of "2WD and full turn" is not counted, so first T seconds (approximately 1 second)
The wait process 70 in the meantime is started.

The weight processing 70 in this case is to confirm that the "front wheel speed increasing 4WD state D" is forcibly maintained by turning on the second solenoid 60 for about one second. After about 1 second has passed, the count of the number of fluctuations of "2WD and full turn" is added once as your own mark, the full turn flag is cleared, and "front wheel speed up 4WD state D" to "rear wheel 2WD state C"", And continue turning.

When the overrun rate in the "rear wheel two-wheel drive state C" does not exceed the predetermined value "B" during one continuous turn such as at the field edge, the full turn flag is turned on again and the second The solenoid 60 is energized to forcibly set the "front wheel speed-increasing 4WD state D" and the weighting process 70 is performed again as described above. When the weighting process 70 is completed, the count of the number of fluctuations of "2WD and full turn" is counted. As a mark, it adds once again, clears the full turn flag, changes from "front wheel speed-up 4WD state D" to "rear wheel 2WD state C", and continues turning. This wait processing is repeated until the number of times exceeds a predetermined constant “N”, even if there is a command for the control operation, the necessity of the control operation is determined.

The time required for the agricultural tractor 14 to turn once at the end of the field requires about 6 to 8 seconds at a speed of about 3 km per hour, and during this 6 to 8 seconds, "2WD (rear wheel two-wheel drive state C ) And full turn (front-wheel speed-increasing 4WD state D), the slip of the rear wheel 3 is measured and "front-wheel speed-increasing 4WD state D" is measured while the number of fluctuations does not exceed the provisionally set 3 times. The necessity of turning is determined and confirmed up to a temporary set number of 3 times.

The rear wheel 3 slips during one continuous turn such as at the end of the field, so that the overrun rate in the "rear wheel two-wheel drive state C" does not exceed the predetermined value "B". If the number of times the rear wheels 3, 3 are not properly transmitting the driving force to the ground during traveling exceeds the set number of times and becomes, for example, 4 times, it is determined that the surface of the traveling field is slippery and the full turn flag is cleared. Without fixing to the control of "front wheel speed increasing 4WD state D" in "turn control I", the front wheels 4, 4 and the rear wheels 3, 3 fuselage until the completion of one continuous turning of the field end is detected. Forcibly tow. When the slip of the rear wheel 3 is less than the set number of times, it is determined that the surface of the traveling field is not slippery, and the vehicle turns in the "rear wheel two-wheel drive state C".

When the turning of the agricultural tractor 14 approaches the end of turning of the agricultural tractor 14 at the end of the field or the like, the driver gradually returns the steering wheel 28 to the straight traveling state side, and the detection of turning completion is performed by detecting the steering angle. This is a control operation change from "turn control I" to "turn control II". Next, the "turn control II" will be described with reference to the flowchart of FIG.

After the control is started, the data in "turn control I" is initialized and the first and second solenoids 59 and 60 are turned on.
The control is started from "rear wheel two-wheel drive state C" with FF. First, it is judged whether or not the 4WD flag, which is the "front and rear four-wheel drive state H" in which the speeds of the front wheels 4 and the rear wheels 3 are substantially equal, is ON. , ”And the determination is made as to whether or not the rear wheels 3, 3 are slipping.

The slip of the rear wheels 3 is determined as the "rear wheel two-wheel drive state C" using the rear axle rotation sensor 9 and the front axle rotation sensor 10 as described above, and the average rotation circumference of the front and rear wheels 4, 3 is determined. It is judged whether there is a difference in speed, and if there is a slip on the rear wheel 3, the first solenoid 59 is turned on, and the front and rear wheels 4, 3 are simultaneously set to the "front and rear four-wheel drive state H" at substantially equal rotational peripheral speeds. The "slip control" 71 subroutine is activated.
If there is no slip on the rear wheels 3, the vehicle continues to travel in the "rear wheel two-wheel drive state C".

The "slip control" 71 will be explained again with reference to the "straight ahead control G" in FIG. 10, but a part thereof will be explained with reference to the flow chart in FIG. The "slip control" in this case is, as described above, in the "slip control" subroutine in which the front and rear wheels 4 and 3 are simultaneously set to the "front and rear four-wheel drive state H" at substantially equal peripheral speeds. It is intended to determine whether or not to continue "H", and when the 4WD lock flag is ON, this "slip control" is not performed. The 4WD lock means that the first solenoid 59 is turned on to actuate the direct coupling clutch 7 to cause the front wheels 4,
4 and the rear wheels 3 and 3 are constantly traveling at substantially the same rotational peripheral speed in the "four-wheel drive front and rear four-wheel drive state H".

In the flow chart, when the 4WD lock flag is not ON, it is judged whether or not the counting of the time "S" seconds (approximately 30 seconds) is started as a range for the judgment. Start counting. Next, it is determined whether or not the rear wheel 3 is slipping on the surface of the field, and if it is slipping, the vehicle travels in the "front and rear four-wheel drive state H" as it is. Since the control is started in the "driving state H", it is determined that the rear wheel 3 is not slipping. Therefore, it is determined whether the weight processing 72 for "R" seconds (approximately 2 seconds) is being processed. If the wait process 72 is not being processed, the wait process for about 2 seconds is started.

When the "R" second wait processing is in progress, it is judged whether or not the control in the 4WD state has continued until approximately 2 seconds have elapsed, and when "R" seconds (2 seconds) have elapsed, " The number of drive changes between "2WD (rear wheel two-wheel drive state C)" and "4WD (front and rear four-wheel drive state H)" is used as a mark for one count addition 73, the 4WD flag is cleared, and the first solenoid 59 and the second Both the solenoids 60 are turned off and the vehicle runs in the "rear wheel two-wheel drive state C". During this running for about 30 seconds, the rotational speeds of the front and rear wheels 4 and 3 have a certain difference or more, and the 4W is again set.
It waits for a D (front and rear four-wheel drive state H) control instruction.

When the count of about 30 seconds has elapsed during traveling, the count of the time "S" seconds (about 30 seconds) is cleared and the count number of drive change between "2WD and 4WD" is about 30 seconds. Then, it is determined whether or not the constant "M" (provisionally 10 times) is exceeded. "2WD and 4WD"
When it is determined that the number of drive change counts does not exceed the constant “M”, the count of drive change between “2WD and 4WD” is cleared, “slip control” 71 is completed, and “straight ahead control G”, which will be described later, etc. Control continues.

When it is determined that the count of drive changes between "2WD and 4WD" exceeds the constant "M", "2WD and 4W"
4WD while clearing the count of drive changes between "D"
Turn on the lock flag to complete the "slip control". 4
The WD lock control is continued for a fixed time. As described above, various "turn control I" and "turn control" relating to "turning control F" are performed.
The description of the control related to "II" and "slip control" is finished, and then "straight ahead control G" will be described with reference to the flowchart of FIG.

The "straight ahead control G" is a control when the steering angle of the steering wheel 28 of the agricultural tractor 14 is "α" or less,
The slip of the rear wheel 3 in the "rear wheel two-wheel drive state C" in which the "brake flag" described later and the above-mentioned "4WD flag" are not turned on is detected, and there is a certain amount of slip (probably about 8% reduction). Sometimes (when the rear wheels do not completely transmit the driving force to the ground), the 4WD flag is turned on, the first solenoid 59 is turned on to make the vehicle run for 4WD, and the "slip control" described in FIG. 9 is performed. After that, the "straight ahead control G" continues.

When the rear wheel 3 does not slip more than a certain amount (tentatively, about 8% reduction), it is again judged whether the front wheel 4 is rotating faster than the rear wheel 3 at the average peripheral speed. If the overrun rate of the front wheels 4 exceeds a predetermined numerical value "A" (probably about 5% increase), the brake flag 74 is turned on to determine the necessity of braking the front wheels 4 by the control means. This is transmitted to a certain controller 13, the first solenoid 59 is turned on to make the vehicle travel in the "front-rear four-wheel drive state H", and the process proceeds to "brake control" described below. In this way, the "straight ahead control G" is divided into two types of control, "slip control" and "brake control", and continues.

When the overrun rate of the front wheels 4 is not more than the predetermined value "A" of about 5% increase, the "straight ahead control G" is continued. If the brake flag 74 is ON at the start of the "straight ahead control G", the process immediately proceeds to "brake control" described below. The operation of this "brake control" will be described with reference to the flowchart of FIG.

Although the control will be described later, when the 4WD lock flag is ON, this "brake control" is completed as it is. In the figure, first, when the time "X" seconds (approximately 30 seconds) has not been counted, the counting of approximately 30 seconds is started as a range for determination, and the front wheel 4 is operated during the time of this determination range. Overrun rate of 5%
Although it is determined whether or not the increase has been reached, as described above, when the "brake control" operation is started, since the start is in "front and rear four-wheel drive state H" traveling, the first and first wheels are connected to the front and rear wheels 4,3. There is no rotation difference.

In this case, the overrun rate of the front wheels 4 becomes equal to or less than the predetermined numerical value "A", and it is determined whether or not the wait processing for the time "Y" seconds (approximately 2 seconds) is being counted, and it is approximately 30.
Wait processing for about 2 seconds within the second determination range is started. This weighting process determines whether or not the control command has been issued during the "front and rear four-wheel drive state H" for about 2 seconds which is the time "Y", and there is a progress of the weighting process for about 2 seconds. If "2WD (rear wheel 2WD state C) and 4W
D (front and rear four-wheel drive state H) "is added once for the purpose of identifying the change of drive, clearing the 4WD flag and driving the agricultural tractor 14 with only the rear wheels 3, 3 It drives in "drive state C", and waits for an instruction to drive 4WD again during this 30-second counting run.

When the count of about 30 seconds has passed, "X"
The count of seconds is cleared, and it is determined whether or not the count number added as a mark for drive change between "2WD and 4WD" exceeds a constant "M" (probably 5 times). "2WD
When it is determined that the count of drive change between "4WD" and "4WD" has exceeded the constant "M" in 30 seconds which is "X" seconds,
The count of the drive change between "2WD and 4WD" is cleared, the 4WD lock flag is turned on for a predetermined time, the "brake control" 77 is completed, and the control in the "straight ahead control G" is performed.

When it is determined that the count value of the drive change between "2WD and 4WD" does not exceed the constant "M" in 30 seconds which is "X" seconds, the drive change between "2WD and 4WD" is performed. Clear the count number that is a mark and "brake control"
77 is completed and the above-described "straight ahead control G" is performed. The "brake control" 77 is such that when the driver applies a sudden brake while traveling with the agricultural tractor 14, the brakes 76, 76 of the rear wheels 3, 3 are braked and the vehicle body tries to stop, but the front wheels 4, 4 are used. If both are not braked at the same time, the front wheels 4 side of the aircraft will proceed at the same traveling speed, and the brake 76 will be less effective, but this state will be automatically judged and the 4WD lock traveling will be performed instantaneously. Since the braking force of the wheels 3 also affects and acts on the front wheels 4 that are drivingly linked, the braking force is increased.

In addition, even if the rear wheel 3 is traveling in the low speed shift state of the transmission mechanism 2 on a steep downhill while traveling 2WD,
When the ground surface is slippery and the aircraft travels at a speed higher than the traveling speed of the wheels, the overrun of the front wheels 4 is determined by the front and rear axis rotation sensors 10 and 9, and the controller 13 as a control means controls 4WD to prevent runaway. When this control operation is, for example, traveling in which it is determined to operate six times or more in 30 seconds, the “front and rear four-wheel drive state H” is first held.

According to the present invention, even if 4WD is instructed, when the front and rear axis rotation sensors 10 and 9 determine that the instruction is not necessary, the controller 13 as a control means immediately automatically travels as 2WD. 2WD is instructed, and when a dangerous state is detected by the front and rear axis rotation sensors 10 and 9 during traveling, the controller 1 which is a control means automatically.
3 is used to switch to 4WD.

[0061]

The present invention has the following technical effects by virtue of the configuration described above. That is, it is possible to minimize damage to the ground by traveling with fine control corresponding to changes in the ground state on the surface of the traveling field, and to exhibit good ground drive transmission performance during traveling.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention.

FIG. 1 is an explanatory diagram of a main part.

FIG. 2 is a side sectional view of a main part.

FIG. 3 is an overall side view.

FIG. 4 is a transmission plan diagram in which the whole is developed.

FIG. 5 is a flowchart of the entire automatic control.

FIG. 6 is a flowchart of a swing control F which is a subroutine.

FIG. 7 is a flowchart of a turn control I that is a subroutine.

FIG. 8 is a flowchart of a turn control II that is a subroutine.

FIG. 9 is a flowchart of a slip control which is a subroutine.

FIG. 10 is a flowchart of a straight-ahead control G, which is a subroutine.

FIG. 11 is a flowchart of a brake control, which is a subroutine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 engine 2 speed change mechanism 3 rear wheels 4 front wheels 5 rear wheel drive rotation shaft 6 front drive shaft 7 direct coupling clutch 8 speed-up clutch 9 rear shaft rotation sensor 10 front shaft rotation sensor 11 rudder angle sensor 13 control means

Claims (1)

(57) [Claims] 1. A four-wheel drive type mobile vehicle in which a driving force of an engine 1 is transmitted to a rear wheel 3 and a front wheel 4 via a plurality of speed change mechanisms 2 and a front wheel 4 side is a steering wheel. The rotation of the rear wheel drive rotary shaft 5 between the rear wheel 2 and the rear wheel 3 is interlocked with the front wheel 4 via the front drive shaft 6, and the front drive shaft 6 is rotated without changing the rotation of the rear wheel drive rotary shaft 5. A direct coupling clutch 7 that turns on and off in a ratio, and a speed increasing clutch 8 that speeds up and turns on the rotation of the rear wheel drive rotation shaft 5 on the front drive shaft 6 are provided, and a rear shaft that detects the number of rotations of the rear wheel drive rotation shaft 5. A rotation sensor 9, a front axle rotation sensor 10 that detects the number of revolutions of the front drive shaft 6, and a steering angle sensor 11 that measures the steering angle of the front wheels 4 are provided, and the detection of each of these sensors 9, 10, 11 is performed. Depending on the value, the direct coupling clutch 7 or speed increasing clutch 8 is turned on. Then, the clutches 7 and 8 are turned off for a short time thereafter, and the sensors 9 and 1 are turned off.
A four-wheel drive system characterized in that a control means 13 is provided for detecting the values of 0 and 11 to measure the road surface condition and determining whether or not the ON operation of the direct coupling clutch 7 or the speed increasing clutch 8 is necessary. Front wheel rotation drive controller for mobile vehicles.