JPH10167033A - Brake restraining device of agricultural working car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly restrain a brake control device at the time of high speed travelling by shutting off interrupting means to be provided on a hydraulic circuit between a solenoid valve to actuate the brake control device and a hydraulic pump by a hydraulic actuator. SOLUTION: Pressure oil flows to a branch circuit from a hydraulic circuit 51 and drops in a hydraulic tank 46 through an orifice 37 at the time of rotating and driving a hydraulic motor 6 by rotation of a driving gear 32 of a front wheel driving transmission shaft 29 as a shift lever is turned to the side of high speed and car velocity is increased. At this time, when a tractor comes to be at car speed enough to electrically restrain brake control by an operational position of the shift lever, the hydraulic motor 6 is rotated at high speed and limits pressure oil of the hydraulic circuit 51 by the orifice 37 and applies back pressure on a change-over valve 5, and accordingly, the change-over valve 5 is changed over to the circuit shut-off side. Consequently, proportional pressure control valves 2R, 2L are electrified because of an electrical trouble, a brake system does not work as a brake circuit 48 is shut-off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction of a brake device for an agricultural machine such as a tractor or a rice transplanter.

[0002]

2. Description of the Related Art Conventionally, in agricultural work machines such as tractors, a solenoid valve is opened by an energization command of a controller and the rear inner wheel is turned on in order to facilitate a small turn on a headland or the like in a field. Some have a brake control device that operates the brake. An agricultural working machine having these brake control devices is disclosed in Japanese Patent Application Laid-Open No. 6-156308.
As shown in the publication, the brake control device detects a shift position of the operator so that the brake control device does not operate on a general road at a high speed, and when the shift position is operated to a high speed side, the controller sends a signal from the controller. There is a technology that stops the energization of the vehicle and checks the operation of the brake control device.

However, in the above-described restraint using electric components, electricity flows to the solenoid valve erroneously due to malfunction of the shift position detection switch, trouble of the controller itself, short circuit, etc. There was a risk that the brakes would operate.

[0004]

The present invention employs the following technical means in order to solve the above problems. That is, in an agricultural work machine having a brake control device that applies a brake to the rear wheel 1 on the inside of the turn in conjunction with the turning operation, the hydraulic pump 45 driven by the engine 12 and the solenoid valve 2 that operates the brake control device is used. The hydraulic circuit of this invention is provided with a connecting / disconnecting means 5 for connecting / disconnecting the circuit, and the connecting / disconnecting means 5 is interrupted by a hydraulic actuator 6 which is driven by using the power of the traveling transmission system, so that the brake control device cannot be operated.

[0005]

The brake restraining device for an agricultural machine constructed as described above shuts off the hydraulic system path 48 to the solenoid valve 2 using the power of the traveling transmission system even if an electrical trouble occurs. Therefore, the brake control device can be reliably suppressed during high-speed traveling, and the agricultural work machine can travel safely.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an agricultural tractor (hereinafter, tractor 10). The tractor 10 has a diesel engine 3 provided inside a bonnet 11 at the front of the fuselage, and a clutch housing, a transmission case 13, a rear transmission case 14 and the like are integrally connected from the engine 3, and is provided below the engine 3. A pair of left and right front wheels 15 are provided on the left and right sides of the rear transmission case 14, respectively. Then, the rotational power of the engine 3 is turned on and off by the main clutch 7 in the clutch housing, the forward / reverse switching is switched by the forward / reverse switching device 8 in the transmission case 13, and the main transmission 9A and the auxiliary transmission 9B are appropriately operated. The transmission is decelerated and transmitted to the rear wheels 1,1, and the front wheels 1,1 can also be driven via the front wheel drive transmission shaft 29.

A brake disk is provided on the rear wheel drive shaft inside the rear transmission case 14, and the brake disk is pressed by an operator's pedal operation or the operation of brake cylinders 49L and 49R, which will be described later. The brake is applied. A steering post 16 is provided behind the hood 11, and a steering 17 is provided to protrude therefrom.
Then, the front wheels 15, 15 are steered by the rotation operation of the steering 17, and the steering operation is detected by a steering angle sensor 18 provided at the turning base of the steering 17.

A floor 19 is provided above the center of the transmission case 13, and fenders 20, 20 are provided at the left and right rear ends of the floor 19 to cover the rear wheels 1, 1 from the front and upward. ing. A cockpit 9 is provided between the left and right fenders 20, 20, and on the side of the cockpit 9, a ground gear of a main shift lever 21 and a sub shift lever 22 for traveling, which will be described later, and a work machine 24 mounted on the rear portion. A position lever 23 for changing the height is provided, and a controller 25 is provided below the cockpit.

At the rear of the rear transmission case 14, a cylinder case 27 having left and right lift arms 26, 26 is provided, and the lift arms 26, 26 are moved up and down by extending and retracting a piston of a hydraulic cylinder 28 inside the case 14. It is configured to operate. Further, a three-point link mechanism including a top link 35 and lower links 36, 36 is provided at a rear portion of the rear transmission case 14, and the working machine 24 is connected to the lower link mechanism so as to be able to move up and down.

The controller 25 has a CPU for processing information of various sensors and switches, a RAM for temporarily storing the information, a ROM for storing a control program for the brake control device, and the like. The input section of the controller 25 includes the steering angle sensor 18, a first speed detection switch 40 of the main transmission lever 21, and a medium speed detection switch 41 of the sub transmission lever 22, which will be described later.
And a low speed / ultra low speed detection switch 42, and solenoids 43, 44 of the proportional pressure control valves 2R, 2L for operating the brakes of the left and right rear wheels are connected to the output side.

Next, the brake control device and the check device will be described with reference to FIG. First, engine 3
At the same time, the controller 25 periodically detects the steering operation of the operator by the steering angle sensor 18. At the same time, the shift positions of the main shift lever 21 and the auxiliary shift lever 22 are detected. And, the shift position is lower than the preset shift position,
That is, if the operator determines that the vehicle is operating at a certain speed and detects a steering operation at a certain angle or more, it is determined that the vehicle is turning in a small turn during the operation, and the solenoid 43 of the proportional pressure control valve 2R (2L) of the rear wheel 1 inside the wheel is turned. Power is supplied to (44). Thereby, the brake is applied to the rear wheel 1 inside the turning of the tractor 10, and the operator can easily turn at the headland in the field without requiring the brake operation.

The hydraulic circuit of the brake restraint device of the tractor 10 will be described. The pump 4 driven by the start of the engine 3 draws oil from a tank 46 serving also as the transmission case 14, and supplies the oil via a pressure reducing valve 47. The pressure is sent to the brake circuit 48. In the brake circuit 48,
A switching valve 5 serving as an intermittent means is provided on the upstream side of the circuit, the end of the switching valve 5 is branched into two, and proportional pressure control valves 2R and 2L are provided respectively. The left and right brake cylinders 49R and 49L are further provided at the tip. The proportional pressure control valves 2R and 2L are configured to be opened by an energization command from the controller 25.

The rotational power reduced by the auxiliary transmission 9B is transmitted to the transmission gear 32 of the front wheel drive transmission shaft 29. The transmission gear 32 is engaged with the input gear 34I of the motor transmission shaft 33 separately. And a motor drive shaft 38 for driving the hydraulic motor 6 to an output gear 34O of the transmission shaft 33.
Of input gears 38 are provided in mesh with each other. The hydraulic motor 6 and the switching valve 5 are connected by a check circuit 51, and a branch circuit is provided in the check circuit 51 to open the tank 46 via the orifice 37.

The brake device constructed as described above is restrained as follows. When the speed of the transmission levers 21 and 22 is shifted to a high speed side to increase the vehicle speed, the drive gear 32 provided on the front wheel drive transmission shaft 29 rotates, and the hydraulic motor 6 is driven and rotated via the transmission shaft 33. At this time, when the traveling speed is low, the pressure oil sent from the hydraulic motor 34 flows into the branch circuit branched from the hydraulic path 51 and falls into the hydraulic tank 46 through the orifice 37.
However, when the vehicle speed increases and the tractor 10 reaches a vehicle speed at which the brake control is electrically controlled by the operation positions of the shift levers 21 and 22, which will be described later, and the hydraulic motor 34 rotates at a high speed, the traction control circuit 51
Is restricted by the orifice 37 and applies a back pressure to the switching valve 5, and the switching valve 5 is switched to the circuit cutoff side.

Thus, even if the proportional pressure control valves 2R and 2L are energized due to an electrical trouble in the controller 25 or a short circuit in the electric circuit, the brake cylinder 4
Since the brake circuit 48 to 9L and 49R is shut off, the brake device does not operate. Therefore, the operation of the brake control is reliably suppressed during high-speed traveling, and safe traveling is enabled.

The means for detecting high-speed running of the tractor 10 will be described with reference to FIG. The main shift lever 21
Is a lever that slides the rotating shaft to operate in an H-shape.
The gear shifts to "1st gear" when operated forward and outward, "2nd gear" when operated backward, "3rd gear" when operated backward and "reverse" when operated forward and inward. Further, a hook-shaped switch operating arm 21B is provided on the lever base 21A of the pivot base so as to protrude rearward, while a first speed detection switch 40 is provided inside the fender 20, and the lever 21 is moved forward. When operated outward, the hook of the operation arm 21B is moved to the first speed detection switch 40.
Is turned on.

The sub-shift lever 22 is an I-type shift type lever, which is "high speed" when turned forward, "medium speed" when pulled backward by a certain angle, and "medium speed" when turned further backward. The gear shifts to "neutral", "ultra low speed" when turned further backward, and "low speed" when turned further backward. The arm portion 22A of the auxiliary transmission lever 22 has
The hook-shaped switch actuating piece 22B protrudes forward. On the other hand, on the side wall of the transmission case 13,
A switch bracket 50 is attached, and a medium speed detection switch 41 and a low speed / ultra low speed detection switch 42 are provided around the central axis of the sub-transmission lever 22. Thus, when the operator operates the sub-transmission lever 22 to "medium speed" (solid line in FIG. 6), the bottom surface of the hook comes into contact with the medium speed detection switch 41 and turns on, thereby operating to "ultra low speed" (FIG. 7
(Solid line) and the hook base portion 22a comes into contact with the low-speed / ultra-low speed detection switch 42 to be turned on. When the lever 22 is turned to “low speed” (two-dot chain line in FIG. 2), the tip end portion 22b of the bottom of the hook turns on the switch 42. Then, the controller 25 sets the conditions under which the brake control device operates as follows: when the low speed / ultra low speed switch 42 is on, and when the first speed detection switch 40 and the middle speed detection switch 41 are simultaneously on, It is configured to make a determination and activate the brake control device.

When the speed of the sub-shift lever 22 is changed to "high speed", the hook 22B is set to the middle speed detection switch 41.
, And the hook is located between the middle speed detection switch 41 and the low speed / ultra low speed detection switch 42 when the speed is shifted to “neutral”. Thereby, the two shift levers 21 of the H type and the I type shift type,
As compared with detecting the shift position using an expensive sensor such as a potentiometer, the shift position of the operator can be detected by a plurality of inexpensive switches.

In the claims, the reference numerals of the members corresponding to the configuration of the embodiment are attached, but the present invention is not limited to the embodiment by the reference numerals.

[Brief description of the drawings]

FIG. 1 is a diagram showing a brake restraint.

FIG. 2 is an overall side view of the tractor.

FIG. 3 is a block diagram showing a connection state of a controller.

FIG. 4 is a diagram showing the state of each detection switch and the operation of brake control.

FIG. 5A is a diagram illustrating a detection switch provided on a rotation base of a shift lever.

FIG. 6 is a diagram B illustrating a detection switch provided on a rotation base of the shift lever.

FIG. 7 is a diagram C showing a detection switch provided on a rotation base of the shift lever.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rear wheel 2 Proportional pressure control valve 3 Engine 4 Hydraulic pump 5 Switching valve 6 Hydraulic motor

Claims (1)

[Claims] 1. An agricultural work machine having a brake control device for applying a brake to a rear wheel 1 inside a turn in conjunction with a turning operation, a hydraulic pump 45 driven by an engine 12 and an electromagnetic valve 2 for operating the brake control device. The hydraulic circuit 48 is provided with a connecting / disconnecting means 5 for connecting / disconnecting this circuit, and the connecting / disconnecting means 5 is cut off by a hydraulic actuator 6 driven by using the power of the traveling transmission system, so that the brake control device cannot be operated. A brake restraining device for an agricultural work machine, characterized in that: