JPH08188134A - Automatic braking controller - Google Patents

Abstract

PURPOSE: To bring smooth turning performance into full play by presetting the braking force of a rear-wheel braking device, and forming it so as to brake it with the stronger braking face than this setting value at the initial stage of braking application. CONSTITUTION: When an auto-lift brake setting switch 42 is turned to ON, auto-lift control is started. In breif, at the time when a controller 41 is so judged that a machine body has come into a state of being turned round on the basis of the detected value of a steering angle sensor 35, a brake-on signal is outputted to a left turning brake solenoid or right turning brake solenoid from the controller 41 in order to brake a rear wheel 18a or 18b at the turning inside, and a hydraulic actuator 32 or 33 becomes turned on and thereby a braking device 26 at the left or a braking device 29 at the right operates. Simultaneously with this, a lifting signal is outputted to a lifting proportional solenoid from the controller 41, whereby a lift cylinder 38 is extended and both symmetrical lift arms 39 and 39 are turned upward, therefore farm working machinery goes up, preventing any possible drag in this farm working machinery at the time of turning operations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic braking control device for a tractor, and more particularly to an automatic braking control device for automatically braking the rear wheel inside a turning in conjunction with the operation of a steering wheel. It is about.

[0002]

2. Description of the Related Art A pair of brake devices, which can operate independently on the left and right sides, are provided on the rear wheels of a tractor. When turning the machine in a field during plowing work, only one brake pedal is depressed. The rear wheels on the inside of the turn are braked to reduce the turning radius of the aircraft.

Further, a sensor is provided in the steering mechanism to detect the steering angle of the steering wheel, and when the steering angle exceeds a certain value, it is considered that the aircraft has entered a turning motion, and the rear wheels inside the turning are automatically operated. There is also known an automatic braking device that automatically brakes.

[0004]

The conventional automatic braking device of this type of tractor automatically brakes the inner rear wheel during turning, but the braking force of the rear wheel is set to be constant. When the set value of the braking force is increased, the inner rear wheel may be locked and the turning trace may be rough depending on the state of the field. On the other hand, when the set value of the braking force is made small, there is a problem that the braking force of the inner rear wheel becomes insufficient and the turning radius becomes large.

Therefore, there arises a technical problem to be solved in order to automatically control the braking force of the automatic braking device of the tractor and to exert a smooth turning performance. The present invention solves this problem. With the goal.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to achieve the above-mentioned object, and provides a tractor which automatically brakes the rear wheel inside the turning in conjunction with the operation of the steering wheel. There is provided an automatic braking control device in which the braking force of the braking device for the rear wheels is set in advance and braking is performed with a braking force stronger than this set value at the initial stage of braking.

[0007]

In the automatic braking control device of the present invention, the braking force of the braking device is preset so that the inner rear wheels do not lock during turning. At the initial braking during turning, braking delay is eliminated by braking the inner rear wheel with a braking force stronger than the set value, and the turning radius of the airframe becomes small. Then, after a lapse of a certain time from the start of braking, the inner rear wheel is braked by the set braking force to prevent the inner rear wheel from being locked.

[0008]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a tractor 11, in which a traveling clutch 13 is provided at a rear portion of an engine 12, and a power transmission mechanism portion 17 such as a front transmission 15 and a rear transmission 16 is continuously provided at a rear portion thereof via a spacer case 14. The power of the engine 12 is transmitted to the rear wheels 18a and 18b.

The power of the engine 12 is the drive switching unit 1.
9 is also transmitted to the front wheels 20a, 20b by means of the drive wheel 9, and inside the drive switching section 19, a four-wheel drive switching device 19a for turning on / off power transmission to the front wheels 20a, 20b at substantially the same speed as the rear wheels, and the front wheel 20a during turning. , 20b are provided with a speed doubling device 19b for transmitting power at a rotation speed approximately twice that of the rear wheels.

On the other hand, left and right brake pedals 21 and 22 are provided on the right side of the spacer case 14 and are pivotally mounted so that they can be independently depressed. If the left brake pedal 21 is depressed, the pedal shaft 23
The rotation causes the brake rod 24 provided on the left side of the spacer case 14 to be pulled, and the left brake arm 25
Rotates forward and the brake device 26 for the left rear wheel operates. When the right brake pedal 22 is depressed,
Brake rod 2 provided on the right side of the spacer case 14
7 is pulled, the right brake arm 28 rotates forward, and the brake device 29 for the right rear wheel operates.

The left and right rear axle housings 3
0 and 31 are provided with hydraulic actuators 32 and 33 in a system different from the linkage of the brake pedals 21 and 22 described above, and when the hydraulic actuators 32 and 33 are turned on, the brake arms 25 and 28 are pressed forward. The left and right brake devices 26 and 29 are formed to operate.

On the other hand, a steering angle sensor 35 is provided on the steering shaft 34 to detect the steering angle of the steering wheel 36. Further, a lift cylinder 38 is provided on the upper part of the rear transmission case 16, and the left and right lift arms 39, 39 are vertically rotated by the expansion and contraction of the lift cylinder 38 to raise and lower a working machine (not shown) to an arbitrary height. Let Further, the lift arm sensor 4 is attached to the rotation base of one lift arm 39.
0 is provided, and the lifting height of the working machine is detected by the lift arm sensor 40. Reference numeral 41 is a controller, 42 is an automatic lift brake (hereinafter referred to as "ALB") setting switch, and 43 is an ALB braking force changeover switch.

FIG. 2 is a block diagram of the control system, ALB
When the setting switch 42 is turned on, the ALB control starts. That is, when the controller 41 determines that the aircraft has entered the turning state based on the detection value of the steering angle sensor 35,
In order to brake the rear wheels 18a or 18b on the inside of the turn, a brake-on signal is output from the controller 41 to the left turn brake solenoid or the right turn brake solenoid, and the hydraulic actuator 32 or 33 is turned on. The left brake device 26 or the right brake device 29 is activated.

At the same time, the controller 41 outputs an ascending signal to the ascending proportional solenoid, and the lift cylinder 38 extends to expand the left and right lift arms 39,
39 rotates upward and the working machine rises to prevent the working machine from being dragged during turning.

Next, the ALB control will be described with reference to the flowcharts of FIGS. Incidentally, since the same control as the conventional one is performed for the automatic lift control of the working machine, only the automatic braking control will be described in the present embodiment.

First, the detection values of the respective sensors including the steering angle sensor are read, and the operating states of switches such as the ALB setting switch are read (step 10).
1). If the ALB setting switch is on, ALB control is entered (step 102), and it is determined whether the ALB braking force changeover switch is set to "weak" (step 103). When the ALB braking force changeover switch is "weak", the routine proceeds to step 104, where it is judged whether or not the vehicle enters the turning state and there is a brake output request from the controller to the inside rear wheel of the turning. Step 1
If the ALB setting switch is OFF in 02, or if there is no brake output request in step 104, step 111
Proceed to, and the left and right rear wheels maintain the brake-off state.

Now, when the detected value of the steering angle sensor exceeds a certain value and the vehicle body enters the turning state, the controller issues a brake output request to the rear wheel on the inside of the turning (steps 104 → 105). For example, when the machine makes a left turn, a brake output request is issued to the left rear wheel, and an initial output is set to the left turn brake solenoid (steps 105 → 106).

Here, the braking force of the rear wheels at the time of turning is
A certain braking force is set in advance so as not to roughen the field, and if the operator operates the ALB braking force changeover switch according to the state of the field, the braking force can be selected from "strong" and "weak". It is configured. However, since a braking delay is likely to occur in the initial stage of turning, as shown in FIG. 5, by temporarily increasing the initial output flow rate as compared with the flow rate of the normal set value and increasing the operating speed of the hydraulic actuator. Eliminate braking delay.

Therefore, at step 106, the signal output is set so as to flow a flow rate larger than the set value flow rate to the left turning brake solenoid, and the time for holding this signal output is set. Then, in step 107, the elapsed time from the generation of the output request is measured, and within the set time, an ON signal is output to the hydraulic actuator for the left brake at the initial flow rate of braking (step 108), and the right brake is also output. Is turned off (step 109).

When a certain time has elapsed since the output request for the left brake was issued, the routine proceeds from step 107 to step 110, and as shown in FIG. 5, the on signal is controlled to be output at the flow rate of the normal set value. .

When the machine body makes a right turn, a brake output request is issued to the right rear wheel, and the routine proceeds from step 105 to step 112 where the initial output is set to the right turn brake solenoid. The control from step 112 to step 116 is the same as the control of the left brake described above.

When the ALB braking force changeover switch is "strong" in step 103, the routine proceeds to step 117, where the aircraft enters the turning state and the controller issues a brake output request to the inside rear wheel of the turning. If so, the process proceeds to step 118. Then, for example, when the aircraft turns left, the hydraulic actuator is operated to the left rear wheel at a flow rate higher than the normal set value flow rate (step 118 → 11).
9) Apply a strong braking force corresponding to the field condition. This flow rate switching may be performed by providing two oil passages having different flow rates and selecting one of the oil passages with a switching valve to switch the oil passage or by changing the flow rate with a flow control valve.

On the other hand, in the case of the structure in which the flow rate of the hydraulic actuator is changed by the pulse control of the electromagnetic proportional control valve, the ALB as shown in the flow charts of FIGS.
Perform control.

When there is a brake output request in step 204, steps 205 to 206
Alternatively, the process proceeds to 212 and the initial on-time setting is performed. At this time, as shown in FIG. 8, the electromagnetic proportional control valve is driven at a duty ratio higher than the normally set duty ratio (step 206 → 207 → 208 → 209,
Alternatively, steps 212 → 213 → 214 → 215). Then, when a certain period of time has elapsed since the brake output request was generated, the brake output is normally performed during the on-time (step 207 → 210 or step 213 → 216).

Thus, the ALB control is performed in the same manner as described with reference to the flow charts of FIGS. 3 and 4. The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified one.

[0026]

The present invention, as described in detail in the above embodiment,
The braking force of the braking device is set in advance so that the inner rear wheel does not lock during turning, and the inner rear wheel is braked with a braking force stronger than the set value at the beginning of braking during turning. Therefore, the braking delay of the automatic braking control is eliminated, and the turning radius of the airframe is reduced.

After a lapse of a certain time from the start of braking, the braking is performed with the braking force of the set value, so that the inner rear wheel can be prevented from being locked, and smooth turning performance can be exhibited without damaging the field.

[Brief description of drawings]

FIG. 1 is a side view of a tractor showing an embodiment of the present invention.

FIG. 2 is a block diagram of a control system.

FIG. 3 is a flowchart showing an example of automatic braking control, part 1.

FIG. 4 is a flowchart showing an example of automatic braking control, part 2;

FIG. 5 is a graph showing changes in flow rate.

FIG. 6 is a flowchart showing another example of the automatic braking control, part 1.

FIG. 7 is a flowchart showing another example of the automatic braking control, part 2.

FIG. 8 is a graph showing changes in on-time.

[Explanation of symbols]

 11 tractors 18a, 18b rear wheels 26, 29 braking device 32, 33 hydraulic actuator 35 steering angle sensor 41 controller

Claims (1)

[Claims] 1. A tractor which automatically brakes a rear wheel inside a turn in association with a steering operation, wherein a braking force of a braking device for the rear wheel is set in advance,
The automatic braking control device is characterized in that the braking force is stronger than the set value at the initial stage of braking.