JPH08310358A - Steering brake for tractor - Google Patents

Abstract

PURPOSE: To variously actuate a incomplete braking force according to a traveling condition, to simplify constitution, to smoothly carry out switching operation, and to easily release a steering brake in the case of erroneous operation, in a steering brake for a tractor. CONSTITUTION: In an automatic lift brake, in which a lift arm is lifted on the basis of a steering angle of a steering handle while a steering brake is operated so as to carry out steering turn, a steering brake for a tractor is constructed of a steering brake switching valve 4, by which an oil pressure is switched between left and right steering brake cylinders 3, and a brake pressure switching valve 5, by which a brake pressure can be manually switched from a full pressure or several levels of partial pressures to an isolating full close.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering brake for a tractor so that different steering swing braking forces can be selected according to the conditions of the field.

[0002]

2. Description of the Related Art In a mode in which a half brake pressure by a solenoid valve is applied to a hydraulic circuit of a steering brake of a tractor, a fixed throttle (orifice) provides only a constant half brake pressure. However, when the semi-braking force under various running conditions such as a dry field, a wet field, or a field varies, it may not be possible to sufficiently cope with the situation.

When the steering wheel is steered and turned depending on the turning angle, the lift arm is automatically raised.
There is a form of automatic lift brake control that puts the work machine in a non-working posture and brakes the steering brake to facilitate reliable turning, but in such automatic lift brake control, control using an electrical signal is used. Therefore, if the steering brake is actuated by an erroneous signal, proper turning may not be performed, or it may be dangerous.

According to the present invention, in such automatic lift brake control, the brake pressure of the steering brake is stopped by a simple manual operation.

[0005]

SUMMARY OF THE INVENTION The present invention is an automatic lift brake in which a lift arm 23 is raised by a turning angle of a steering handle 17 and a steering brake 32 is braked to steer and turn. Steering brake switching valve 4 for switching hydraulic pressure to 3
And a brake pressure switching valve 5 that can be manually switched from full brake pressure or half-stage half pressure to full shutoff.

[0006]

In operation of the tractor, when the steering handle 17 is operated at a turning angle of a certain level or more, the lift arm 23 is raised by the output from the control, and the working machine is raised to the non-working position. The steering brake 32 on the steering side is braked and turned, and the work traveling is turned back. Among these, the steering brake switching valve 4 selects the hydraulic pressure supply path to the left and right steering side brake cylinders 3 (3L, 3R), and the brake pressure switching valve 5 selects each of these brakes. The hydraulic pressure to be supplied to the cylinder 3 is switched between a plurality of stages of half pressure depending on the selection or the total pressure in the secondary pressure side circuit 2 and supplied, and the hydraulic pressure is selected in multiple stages according to the running conditions. be able to.

As described above, since the brake cylinder 3 of the steering brake 32 receives the half pressure which is switched and selected according to the steering condition, an appropriate steering braking force according to the traveling condition can be obtained. Thus, it is possible to make a smooth steering turn. Further, in the automatic lift brake control, when the turning control is not suitable, or when the steering brake 3 is erroneously operated,
When the control of No. 2 is desired to be stopped, the brake pressure switching valve 5 is manually switched to the fully closed position to cut off the hydraulic pressure supply to the steering brake cylinder 3 and the steering brake 32 does not work.

For this reason, when stopping and stopping the braking of the steering brake 32 due to erroneous operation or automatic turning, the brake pressure switching valve 5 can be easily and quickly operated by manually switching it to the fully closed position. The configuration is also simple.

[0009]

EXAMPLE A tractor vehicle body 12 includes a front engine E, a clutch housing 13 and a front mission case 1.
4 and the rear mission case 15 are connected to each other, the front axle housing is supported below the front axle bracket 16 on the lower side of the engine E, and the front wheels 18 which can be steered by the steering handles 17 are provided on both left and right sides.
Further, the rear wheels 20 are mounted on the outer ends of the rear axle housings 19 on both left and right sides of the rear mission case 15 by means of shafts 21.
The hydraulic case 2 is provided above the rear mission case 15.
2 has a lift arm 23 that is vertically rotated by expansion and contraction of an internal hydraulic cylinder, and a rotary cultivator connected to a rear end portion of the vehicle body 12 by a three-point link mechanism such as a top link or a lower link. You can control the working machine up and down.

The cockpit 24 is located between the left and right fenders 25, and the shift lever 2 arranged on the fenders 25
6, the lift lever (position lever) 27, the operation tool of the operation box 28 and the like can be operated. A pair of left and right steering brake petals 30 is arranged on the control floor 29. By depressing the brake petals 30, a steering mechanism provided in the left and right rear axle housings 19 is disengaged via a link mechanism 31. The steering-side brake 32L or 32R is braked so that the steering-side rear wheel 20
Brake the rotation of.

A steering post 34, on which the steering shaft 33 of the steering handle 17 is mounted, is provided with a steering sensor 35 including a potentiometer for detecting the steering angle of the steering handle 17, and the steering handle 17 has a certain angle or more. The structure of an automatic lift brake capable of raising the lift arm 23 to the non-working height by the output from the controller CPU and detecting the turning steering angles 32L and 32R by detecting the turning steering angle of I am trying.

In the traveling transmission mechanism, reference numeral 36 is a differential device in the rear transmission case 15, which differentially transmits to the left and right rear axles 21. Reference numeral 37 denotes a diff device in the front axle housing, which differentially transmits the left and right front wheels 18. Reference numeral 42 denotes a full-turn clutch, which is provided with a speed increasing clutch that shifts the power transmission to the front wheels 18 from substantially the same speed (4WD running) as the rear wheels 20 (front wheel speed increasing).

The power steering 3 by the full turn clutch 42, the steering brake 32, and the steering handle 17.
A hydraulic circuit such as the horizontal control device 8 for maintaining and controlling the lift arm 23, the lift arm 23, and the working machine horizontally is configured as shown in FIG. P1 is the main pump, P2 is the power steering pump,
T is a tank port. The full turn clutch can be disengaged by hydraulically operating the clutch cylinder 39, and the left and right steering clutches and brakes 32L, 3
2R can be braked by hydraulically operating the brake cylinders 3L and 3R. The lift arm 23 can be operated by the lift cylinder 40, and the horizontal control can be operated by expanding and contracting the horizontal cylinder 41.

A pressure reducing valve 1 is provided in the hydraulic circuit of the hydraulic pump P1, and a constant pressure is maintained in the secondary pressure side circuit 2. The secondary pressure side circuit 2 is provided with a clutch cylinder 39 of a full turn clutch 42 which is expanded and contracted by a switching valve 43, and passes through the brake pressure switching valve 5 and the left and right steering brake switching valve 4 to connect the left and right brake cylinders 3L and 3R. It is provided to operate. Further, the pressure is divided into the lift cylinder 40 and the horizontal cylinder 41 via the pressure reducing valve 1 and the flow dividing valve 44, and in the hydraulic circuit on the side of the lift cylinder 40, an electronically operated ascending control valve 45 and a descending control valve 46 are provided. And the horizontal control valve 4 is provided in the hydraulic circuit of the horizontal cylinder 41.
7 is provided.

The steering brake switching valve 4 is electromagnetically actuated by an output from the controller CPU, and by this switching, either the left or right brake cylinder 3 is operated.
When L or 3R is actuated, the link mechanism 3 that is interlocked with the left and right petals 30 by this push piston
The brake arm 48 on the left-right opposite side is rotated to brake the steering brakes 32L and 32R. The brake pressures of the steering brakes 32L and 32R are selected by the brake pressure switching valve 5 and the rotary pool 10 to a pressure suitable for the traveling condition.

The brake pressure switching valve 5 is not shown. When the driver operates the changeover switch provided near the instrument panel to the high pressure brake side or the low pressure brake side, the output from the controller CPU is electromagnetically changed over, and the throttle 49 is opened from the secondary pressure side circuit 2. A total pressure circuit 6 for sending the total hydraulic pressure supplied to the brake cylinders 3L, 3R side and a total pressure circuit 6 by switching a part of the hydraulic pressure to the tank port T by switching to a plurality of throttle degrees by the rotary pool 10. It is configured to switch to the half-pressure circuit 11 that sends at a lower pressure.

The rotary pool 10 has a large aperture,
Forming different diaphragms 7, 8 and 9 for medium and small, and switching lever 5
0 is manually or automatically switched and rotated, and the half pressure circuit 11 is passed through the throttle 7, 8, or 9 to the tank port T, and the secondary pressure side circuit 2 is connected to the brake cylinder 3L,
By releasing a part of the hydraulic pressure supplied to 3R in accordance with the degree of throttling of these throttles 7, 8, 9, etc., the brake cylinders 3L,
Change or adjust the brake pressure applied to 3R. Therefore, the brake pressure acting on the brake cylinders 3L, 3R is set to decrease in the order of total pressure circuit 6> throttle 9> throttle 8> throttle 7.

A push pin 57 is provided on the side opposite to the solenoid 55 of the brake pressure switching valve 5 as described above. By pushing the push pin 57 with the operating lever 58, the brake pressure switching valve 5 is moved to the full pressure circuit 6. It is possible to switch from the half pressure circuit 11 to the fully closed circuit 59. Therefore, even if the brake pressure switching valve 5 is operated at full pressure or half pressure by the output from the controller CPU to the solenoid 55 as described above, when the push pin 57 is pushed by the operation lever 58, the brake Since the pressure switching valve 5 is switched to the fully closed position, the brake pressure in the operating steering brakes 3L and 3R does not rise, and the steering braking cannot be activated.

The automatic lift brake mode is selected by the steering mode switching tool in the operation box 28, and the diaphragms 7, 8, 9 etc. corresponding to the conditions of the working field are selected by the switching lever 50 (or full turn). If the turning by the clutch 42 is selected), the steering sensor 35 detects the turning angle by the steering handle 17 during the steering turning, and the lift arm 23 is raised by the output of the raising control valve 45. The work machine is raised to the non-working position, the front wheels 18 are transmitted at a higher speed than the rear wheels 20, and the brake cylinders 3L or 3R on the turning side are
Actuated by the selected throttle 7, 8 or 9 or under hydraulic pressure by the total pressure circuit 6, the brake 32
L or 32R is braked and turned.

2 and 3, sectional views of the steering brake switching valve 4, the brake pressure switching valve 5, and the rotary pool 10 are shown. Reference numeral 52 is a detent ball that divides the rotary pool 10 into four equal angles. Can be locked in the detent hole 51 at the turning operation position. In addition to the throttles 7, 8 and 9 arranged at the respective locking positions, a T port that does not apply hydraulic pressure to the brake cylinders 3L and 3R by fully opening to the T port is arranged. Reference numerals 53 and 54 denote solenoids of the steering brake switching valve 4, which are output from the controller CPU together with the solenoid 55 of the brake pressure switching valve 5. 56 is a valve body.

In FIG. 6, the point different from the above example is that the operation of the brake pressure switching valve 5 is performed by the output of the solenoid 60 instead of the operation of the push pin 57, and the switch is manually turned on. The solenoid 60 switches the brake pressure switching valve 5 to the fully closed position. In FIG. 7, a difference from the above example is that a sensor 62 for detecting the ridge A on a part of the vehicle body 12 or a part of a working machine 61 such as a rotary tiller.
By providing the sensor 62 to detect the ridge or the distance to the ridge, the turning by the automatic lift brake control is stopped and the alarm 63 is operated. Prevents damage to work equipment due to automatic lift brake control at the ridge.

The sensor 62 may be of an ultrasonic type, and detects the distance between the vehicle body 12 and the ridge A and detects a protruding portion such as the water supply port B to control the ascent. Steering brake 3 such as valve 45 and solenoids 53 and 54
2 Release the braking output to prevent turning by the automatic lift brake control. The operator is notified of such a stop of the automatic lift brake control by an annunciator 63. The annunciator 63 may be a visual indicator lamp, a buzzer with sound, or a sound. Good. Further, the sensor 62 may be provided at the most laterally protruding portion such as the lateral end portion 64 of the working machine 61.

In FIG. 8, the difference from the above example is that the working machine lifted by the automatic lift control outputs the lowering control valve 46 after a lapse of a fixed time from the detection of a large change in the transmission load of the working machine 61. Then, it is automatically lowered to the working position. A load sensor 65 is provided so that the load of the working machine 61 is detected from the torque fluctuation of the power take-off shaft at the rear portion of the vehicle body 12. The fixed time t is a timer provided in the controller CPU and may be set as a time required for steering turning. The time t may be adjusted by a dial or the like.

In FIG. 9, the difference from the above example is that a steering angular velocity sensor 66 for detecting the rotational angular velocity in the steering of the steering wheel 17 is provided in place of the steering sensor 35. This steering angular velocity When the angular velocity detected by the sensor 66 exceeds a certain level, the working machine 61 is raised. 10, a difference from the above example is that a diff shaft rotation sensor 67 is provided in place of the load sensor 65, and the diff shaft rotation sensor 67 detects the differential to lower the work machine 61 after a certain time t. To control. Differential shaft rotation sensor 67 Detects the number of rotations of the left and right rear axles 21 and the differential shafts transmitted to the rear axle 21 in the differential device 36 of the rear axle 21, and calculates the difference between the left and right rotations to determine whether there is a differential. Is determined by the controller CPU.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a tractor operation unit.

FIG. 2 is a sectional view of the brake switching valve portion.

FIG. 3 is a side sectional view and a front sectional view of a rotary pool portion.

FIG. 4 is a side view of the tractor.

FIG. 5 is a steering transmission system path diagram and block diagram.

FIG. 6 is a hydraulic circuit diagram of an operation unit showing another embodiment.

FIG. 7 is a plan view of a tractor working machine showing another embodiment and a control block diagram thereof.

FIG. 8 is a block diagram of automatic lift control according to another embodiment and a flowchart thereof.

FIG. 9 is a block diagram of automatic lift control showing another embodiment and a flowchart thereof.

FIG. 10 is a block diagram of automatic lift control showing another embodiment and a flowchart thereof.

[Explanation of symbols]

 3L Left brake cylinder 3R Right brake cylinder 4 Steering brake switching valve 5 Brake pressure switching valve 6 Full pressure circuit 7 Throttling 8 Throttling 9 Throttling 11 Half pressure circuit 17 Steering handle 23 Lift arm 32 Steering brake 57 Pushpin 58 Operating lever 59 Fully closed circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuo Fujita, No. 1 Yakura, Tobe-cho, Iyo-gun, Ehime Prefecture, Engineering Department, Iseki Agricultural Machinery Co., Ltd. (72) Masayuki Kamada No. 1 Yakura, Tobe-machi, Iyo-gun, Ehime Technology In-house (72) Inventor Seiji Kananami 1 Yakura, Tobe-cho, Iyo-gun, Ehime Pref.Iseki Agricultural Machinery Co., Ltd. (72) Inventor Koji Koyama 1 Yakura, Tobe-cho, Iyo-gun, Ehime Pref.

Claims (1)

[Claims] 1. An automatic lift brake in which a lift arm 23 is raised by the turning angle of a steering handle 17 and a steering brake 32 is braked to steer and turn, and a hydraulic pressure is switched to the left and right steering brake cylinders 3. A directional braking brake for a tractor, which is provided with a directional brake switching valve 4 and a brake pressure switching valve 5 which can be manually switched from full pressure or half pressures of a plurality of stages to full closure of interruption.