JP2003261059A - Turning control device for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turning control device of a working vehicle, in which a body is smoothly turned by gently performing connecting operation of a front wheel speed increasing device 5 with side brakes. <P>SOLUTION: The working vehicle is provided with: the front wheel speed increasing device 5 that makes the number of revolution of front wheels 3 faster than a rotational peripheral velocity of rear wheels 4 based on a steering turning angle not less than a set value; and the side brakes 11L, 11R disposed to right and left rear wheel drive systems reaching the rear wheels 4 from a rear wheel differential device 16. When the steering turning angle of the front wheels is not less than the set value, one of controls is selectively performed hydraulically and electrically, which controls are a turning control for the body by automatically operating only the front wheel speed increasing device 5 and a turning control for the body by operating the front wheel speed increasing device 5 and side brakes 11L, 11R. In the turning control device of the working vehicle, a hydraulic clutch 50 of the front wheel speed increasing device 5 and brake working cylinders 17L, 17R of the side brakes 11L, 11R are operated through a hydraulic pressure governing mechanism disposed in the same hydraulic circuit to gently perform the connecting operation of the front wheel speed increasing device 5 with that of side brakes 11L, 11R. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning control device for a work vehicle such as a tractor.

[0002]

2. Description of the Related Art Conventionally, an agricultural tractor, which is an example of a work vehicle equipped with front wheels and rear wheels, requires a small turning radius to change the direction of the vehicle body at the ridges when working in a field. When the cutting angle of is above the set value, the front wheel speed increasing device that makes the rotation peripheral speed of the front wheels faster than the peripheral speed of the rear wheels is automatically operated to make a small turn of the aircraft (called a quick turn). The inner rear wheels driven by the differential gear are braked by the side brakes to change the direction of the aircraft for a smaller turn (quick turn +
It is called "auto brake tongue".

[0003]

In the conventional tractor as described above, the operation of the front wheel speed increasing device is performed by turning on and off the hydraulic clutch.
FF is generally used, and the side brake of the rear wheels is generally performed by an operation link mechanism or the like. Therefore, when performing the above-mentioned quick turn + auto brake turn, it is difficult to adjust the timing for the interlocking operation of the hydraulic clutch on operation and the side brake braking operation, and the operability at the time of turning the aircraft is accompanied by a slight shock during the interlocking operation. Had lowered.

[0004]

A turning control device for a work vehicle according to the present invention is made to solve the above-mentioned problems, and a steering angle of a steering wheel whose front wheel 3 is equal to or more than a preset value is set. Based on the above, the front wheel speed-increasing device 5 for increasing the rotational peripheral speed of the rear wheel 4 and the side brakes 1 arranged in the left and right rear wheel drive systems from the rear wheel differential device 16 to the rear wheel 4.
1L and 11R, when the steering angle of the front wheels 3 exceeds a set value, control is performed to automatically operate only the front wheel speed increasing device 5 to turn the vehicle body, and to operate the front wheel speed increasing device 5 and the side. In a working vehicle that hydraulically and electrically selects and selectively operates the brakes 11L and 11R to control the vehicle to turn, the hydraulic clutch 50 of the front wheel speed increasing device 5 and the brakes of the side brakes 11L and 11R. By operating the operating cylinders 17L and 17R via the hydraulic pressure adjusting mechanism provided in the same hydraulic circuit, the operation of the front wheel speed increasing device 5 and the operation of the side brakes 11L and 11R are gently connected. .

Further, the pressure increasing characteristic of the pressure adjusting mechanism is made small when only the front wheel speed increasing device 5 is operated, and is made large when operating the front wheel speed increasing device 5 and the side brakes 11L, 11R. .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION One example of an embodiment of the present invention is shown in FIG.
~ It demonstrates with reference to FIG.

FIG. 1 is a block diagram showing a schematic structure of an agricultural tractor which is a work vehicle according to the present invention, and FIG. 2 is a development explanatory view showing a transmission system of the same.

Reference numeral 1 denotes a traveling machine body of a tractor. The traveling machine body 1 has an engine E for generating traveling power of the machine body, work power, various hydraulic pump driving forces, and the like. There is provided a transmission case 2 in which a gearbox is installed, front wheels 3 and 3 and rear wheels 4 and 4 driven by traveling power output from the gearbox of the transmission case 2.

The front wheel drive system has a constant speed drive state in which the front wheel 3 is branched from the rear wheel drive system so that the rotational peripheral speed of the front wheel 3 is substantially the same as the rotational peripheral speed of the rear wheel 4, and the rotational peripheral speed of the front wheel 3. The rear wheel 4
The front wheel speed increasing device 5 capable of switching to a speed increasing drive state in which the speed is driven at a speed approximately twice the peripheral speed of the vehicle.

Reference numeral 6 is a power steering cylinder for forcibly steering the front wheels 3, and the power steering cylinder 6 operates according to the switching operation of the power steering unit 6b accompanying the operation of the steering wheel 6a. Steer. Then, the steering angle of the front wheels 3 is detected by a steering angle sensor 6S attached to the power steering cylinder 6, and at the same time, the steering angle sensor 6S is detected.
The detection result of S is the control device (controller) 10 described later.
It is designed to be input to.

That is, when the steering angle of the front wheels 3 exceeds a predetermined angle (for example, 40 degrees), the control device 10 switches the front wheel speed increasing electromagnetic valve 13 to drive the front wheel speed increasing device 5 at a constant speed. It is configured to switch from the state to the speed-up drive state, and the front wheel 3 does not become a turning resistance of the traveling vehicle body 1 based on the automatic speedup of the front wheel 3, and the vehicle body makes a small turn (called a quick turn). Is performed.

Further, 11L and 11R are left and right side brakes for independently braking the left and right rear wheels 4, and the side brakes 11L and 11R are left and right brake pedals provided in a driving operation section of the traveling machine body 1. 14L, 14R
To the side brakes 11L, 12R by the driver's depressing operation of the left and right brake pedals 14L, 14R.
It is designed to operate 11R.

Further, 17L and 17R are left and right brake actuating cylinders (automatic brake turning control cylinders). The brake actuating cylinders 17L and 17R are connected to the left and right actuating links 12L and 12R, respectively. A solenoid valve for turning a brake (a brake control valve for turning an automatic brake) 18 which is switched and controlled by the control device 10 is connected through a hydraulic pipe.

Then, when the steering angle of the front wheels 3 exceeds a predetermined angle (for example, 40 degrees), the control device 10 switches the electromagnetic valve 18 for brake turning to the brake actuation cylinder 17L (the inside of the turn). 17R) to selectively actuate the side brake 11L.
By the operation of (11R), an automatic brake turn for automatically turning the traveling machine body 1 in a small turn can be performed.

Numerals 19L and 19R are brake actuation detectors for detecting the actuation of the left and right brake actuation cylinders 17L and 17R.
17R moves full stroke and side brake 11
When the L and 11R are activated, they are detected and the control device 10
To inform.

The power from the rear wheel differential device 16 (FIG. 2) of the rear wheel drive system is output to the left and right differential shafts 16L and 16R. The side brakes 11L and 11R described above are mounted on the differential shafts 16L and 16R, and when the side brakes 11L and 11R are operated, the differential shafts 16L and 16R are
16R will be braked.

The brake swing electromagnetic valve 18 shown in FIG. 1 has the "quick turn control" shown in FIG. 6 and the "quick turn + brake" shown in FIG. 7 according to the hydraulic control circuit diagram shown in FIG. 3 and the control block diagram shown in FIG. Turn control ”can be selected.

Reference numeral 26 in FIG. 1 is a traveling system selection switch provided on the side of a driver's seat (not shown). This traveling system selection switch 26 is input to the control device 10.
The driver can operate the switch in advance according to the traveling state of the traveling machine body 1, the work content, the situation in the field, and the like to select the traveling method at the time of turning the machine body. For example, when performing a manual operation using the steering wheel 7 and the left and right brake pedals 14L and 14R, the turning automatic "OFF" position is
When only the front wheel speed-increasing device 5 is automatically operated by the turning angle of the front wheel 3 (quick turn control), the front wheel speed-increasing "ON" position is set.
When the brake is operated (quick turn + auto brake turn control), it is configured so that it can be selected to the front wheel speed increase "ON" + rear wheel brake "ON" (in this case, the side clutch remains connected). ing.

2, reference numeral 15 is a front wheel actuating device, 31 is a main clutch, 32 is a main shaft, and 33 is a PTO drive system. The PTO drive system 33 is equipped with a PTO transmission and a forward / reverse switching device. is there. Further, 34 is a drive shut of the front wheel drive system branched from the rear wheel drive system, and 35
Is a propeller shaft that transmits power to the front wheels 3.

In the turning device for a work vehicle having the above-described structure, as shown in FIG. 2, the power from the engine E is normally transmitted to the main shaft 32 via the main clutch 31, and further in the transmission case 2. The power transmitted by the provided main transmission and auxiliary transmission is transmitted from the drive shaft 34 to the front and rear front wheel drive systems and rear wheel drive systems, and also through the PTO transmission and PTO forward / reverse switching device. The generated power is finally transmitted to the PTO shaft for running and various agricultural work.
The driver can previously select the turning method of the traveling machine body 1 by operating the traveling method selection switch 26 in accordance with the traveling and working environment.

Here, when the driver operates the traveling system selection switch 26 to cause the turning angle of the front wheels 3 and the front wheel speed increasing device 5 to interlock with each other, and when the turning angle of the front wheels 3 exceeds a predetermined angle, , The front wheel speed-increasing device 5 automatically operates to speed up the front wheels 3, and the side brakes 1 on the inside of the turn are
1L (11R) is the brake operating cylinder 17L (17R
R) to lock (stop) the differential shaft 16L (16R). Therefore, the rear wheels 4 on the outside of the turn are driven at double speed by the rear wheel differential device 16.

A tractor capable of making such a turn is equipped with a hydraulic valve mechanism 7 as shown in FIG. 3 and FIG. 4 of another embodiment to perform the quick turn control and the quick turn + auto brake turn control. The configuration is as follows. Therefore, in the control block diagram of FIG. 5, in the mode of the control device 10, a quick turn setting switch 26a of the traveling system selection switch 26 and a quick turn + auto brake are provided on the input side of the controller 10a including a CPU. The turn setting switch 26b and the steering angle sensor 6S are connected,
A quick turn solenoid 5S, a left brake solenoid 18L, and a right brake solenoid 18R are connected to the output side of the controller 10a.

Next, the hydraulic circuit diagram of FIG. 3 will be described.

This hydraulic valve mechanism feeds the hydraulic oil, which is pumped by the pump P via the strainer, to the power steering cylinder 6 via the sequence valve 70, and operates to the upstream side of the sequence valve 70 in the oil feeding direction. A pressure reducing valve 71 for turning control for reducing the pressure of the oil to a constant pressure is provided,
From the pressure reducing valve 71 to the electromagnetic valve 18 for turning the brake.
Are connected by two oil passages 7a and 7b.

Then, in one of the oil passages 7a, a switching valve 7 for turning control which is connected to the other oil passage 7b from the upstream side in the oil feeding direction.
2 is provided on the lower side thereof, and a pressure regulating valve mechanism 73 including a pressure reducing valve 73a on the oil passage 7a side and a relief valve 73b on the oil passage 7b side is provided as a hydraulic pressure adjusting mechanism.
The hydraulic clutch 50 for quick turn is connected as a hydraulic clutch for turning the front wheel speed increasing device 5 on and off, and the front wheel speed increasing device 5 is operated.

With this configuration, the pressure regulating valve mechanism 73 suppresses a sudden pressure increase between the brake swing electromagnetic valve 18 side and the quick turn hydraulic clutch 50 side when the switching valve 72 is turned on and operated. As shown in, during quick turn + auto brake turn control, boost control (A) is performed so as to increase the hydraulic pressure with a predetermined characteristic so that the time for boosting to a predetermined hydraulic pressure is moderately long and moderate. The hydraulic clutch 50 for quick turn and the brake operating cylinders 17L and 17R as brake control cylinders for turning the automatic brake can be loosely connected so that the turning of the airframe with less shock can be smoothly performed. ing. (Quick Turn Control) When quick turn control is performed by the selection operation of the traveling method selection switch 26 while working in the field, as shown in the flowchart of FIG. 6, the controller 10a in step S1. When the setting values of various setting devices and the sensor values of various sensors are read by reading each sensor and switch by
In step S2, the state of the quick turn setting switch 26a is read.

When the steering wheel 6a is steered by a predetermined angle or more by the operator's operation and the steering angle sensor 6S detects it, it is determined that there is a quick turn request in step S3, and the boost control (A) described above is performed in step 4.
For example, as shown in the graph of FIG. 8, the pressure is increased in a unit of time so that the pressure turns gradually after the rising, and the pressure is gradually changed so as to turn in the pattern of the pressure increasing control (A). There is.

(Quick turn + automatic brake control)
When the "quick turn + auto brake turn control" is performed by the selection operation of the traveling system selection switch 26, as shown in FIG. 7, the controller 10a reads the respective sensors and switches in the same manner as described above in step S1. Done, quick turn + in step S2
When the automatic brake turn setting switch 26b is read and the steering angle sensor 6S detects that the steering wheel 6a is steered by a predetermined angle or more in step S3, it is determined that a quick turn and an automatic brake turn are required.
In step S4, the pressure rising characteristic of the boost control (B) shown in FIG. 8 is performed.

That is, in the case of this control, the amount of pressure increase per hour is made larger than that in the pressure increase control (A), and the hydraulic pressure increase speed is made faster than the quick turn control. Even if 17L and the hydraulic clutch 50 for quick turn are operated at the same time, braking can be performed without reducing the operating speed of the brake operating cylinders 17L, 17L, so that a braking delay is prevented and the operation of the front wheel speed increasing device 5 and the side brake are prevented. 11L,
It is possible to smoothly connect the 11R operations to enhance the turning response and perform a smooth turning.

Further, there is a feature that the shock at the time of switching both valves when the normal traveling (straight traveling) is switched to the above-mentioned traveling traveling can be suppressed and the operability of the traveling can be improved.

Next, a hydraulic circuit diagram according to another embodiment shown in FIG. 4 will be described. Note that the description of the same configurations and operations as those of the above-described embodiment will be omitted.

This hydraulic valve mechanism 7 also serves as a hydraulic pressure adjusting mechanism by omitting the pressure adjusting valve mechanism 73 in the embodiment shown in FIG. 3 and using the pressure reducing valve 71 as an "electromagnetic proportional pressure reducing valve". This pressure reducing valve 71
The pressure adjustment is performed by appropriately controlling the value of the current flowing to the solenoid at the time of switching the switching valve 72, and "quick turn control" and "quick turn + auto brake turn control" similar to those in the above-described embodiment are performed. I am able to do that.

That is, in the quick turn control, FIG.
8, the electromagnetic proportional pressure reducing valve 71 makes a quick turn by the boost control (A) of FIG. 8, and in the quick turn + auto brake turn control, the pressure reducing valve 71 of FIG. There is also an advantage that the quick turn + automatic brake turning can be performed by the boost control (B), and the same operation and effect as those of the above-described embodiment can be obtained.

[0034]

As described above, according to the turning control device for a working vehicle of the present invention, the front wheel 3 makes the rotational speed of the front wheel 3 faster than the peripheral speed of rotation of the rear wheel 4 on the basis of the steering turning angle which is equal to or more than the set value. When the steering angle of the front wheels 3 is equal to or more than the set value, the speed increasing device 5 and the side brakes 11L and 11R arranged on the left and right rear wheel drive systems from the rear wheel differential device 16 to the rear wheels 4 are provided. , The control for automatically operating only the front wheel speed increasing device 5 to turn the vehicle body, and the front wheel speed increasing device 5
Of the front wheel speed-increasing device 5 and the side brake 11L in a working vehicle that hydraulically and electrically selects the operation of the front wheel speed increasing device 5 and the control of operating the side brakes 11L and 11R to turn the machine body. , 11R brake actuating cylinders 17L, 17R are actuated via hydraulic pressure regulating mechanisms provided in the same hydraulic circuit, so that the operation of the front wheel speed increasing device 5 and the operation of the side brakes 11L, 11R are gently connected. As a result, when the front wheel speed increasing device 5 and the side brakes are simultaneously actuated by hydraulic pressure, the connection operation between the two is performed gently, so that it is possible to prevent a shock at the time of turning the machine body and perform a smooth turning.

By making the pressure increasing characteristic of the pressure regulating mechanism small when operating only the front wheel speed increasing device 5, and increasing when operating the front wheel speed increasing device 5 and the side brakes 11L and 11R, It is possible to smoothly perform the turning of the vehicle body only by the front wheel speed increasing device 5 and the turning by the front wheel speed increasing device 5 and the side brakes, and it is possible to perform a turn with good responsiveness during both turnings.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a tractor.

FIG. 2 is a development explanatory view showing the transmission system of FIG.

FIG. 3 is a hydraulic circuit diagram of a turning control device.

FIG. 4 is a hydraulic circuit diagram according to another embodiment of the turning control device.

FIG. 5 is a control device.

FIG. 6 is a flow chart showing quick turn control.

FIG. 7 is a flow chart showing quick turn + auto brake turn control.

FIG. 8 is a boost control pattern diagram.

[Explanation of symbols]

1 traveling vehicle 3 front wheel 4 rear wheel 5 front wheel speed increasing device 11L, 11R side brakes 17L, 17R brake actuation cylinder 50 quick turn hydraulic clutch 71 pressure reducing valve (hydraulic pressure regulating mechanism) 72 switching valve 73 pressure regulating valve mechanism (hydraulic pressure regulating) Pressure mechanism)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2B043 AA04 AB08 BA02 BB01 DA04                       DB05 DB06 DB07 DB08 DB17                       DB18 DB20 DB21                 3D052 AA02 AA06 BB08 DD03 EE03                       FF01 FF05 GG01 GG03 GG05                       HH02 HH03 JJ02 JJ03 JJ08                       JJ20 JJ21 JJ22 JJ23 JJ26                       JJ37

Claims (2)

[Claims] 1. A front wheel speed-increasing device 5 for increasing the rotational speed of the front wheels 3 faster than the peripheral speed of rotation of the rear wheels 4 based on a steering angle that is greater than a set value, and a rear wheel differential device 16 to a rear wheel 4. Side brakes 11L arranged on the left and right rear wheel drive systems,
11R, control for automatically operating only the front wheel speed increasing device 5 to turn the vehicle body when the steering angle of the front wheel 3 exceeds the setting, the operation of the front wheel speed increasing device 5, and the side brake 11L. , 11R
In the working vehicle which hydraulically and electrically selects the control for turning the vehicle body by operating the hydraulic clutch 50 of the front wheel speed increasing device 5 and the brake operating cylinders 17L of the side brakes 11L and 11R. 17
By operating R via a hydraulic pressure adjusting mechanism provided in the same hydraulic circuit, the operation of the front wheel speed increasing device 5 and the operation of the side brakes 11L, 11R are configured to be gently connected. Turning control device for working vehicles. 2. The pressure rising characteristic of the hydraulic oil of the pressure regulating mechanism is set low when only the front wheel speed increasing device 5 is operated, and is high when operating the front wheel speed increasing device 5 and the side brakes 11L, 11R. The turning control device for a work vehicle according to claim 1, which is configured.