JP2000211389A - Turning device for work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a turn while driving that is appropriate for the surrounding conditions of the area of the turn, by providing a steering means for changing the drive speed of the running device during turning near a steering member, in a work vehicle such as a tractor having a pair of left and right running devices for driving by means of a continuously variable transmission. SOLUTION: After driving force from the engine has been reduced by a sub transmission, it is then transmitted via a front wheel transmission shaft and a front wheel differential gear to a pair of left and right front wheels of a tractor. Meanwhile, the driving force is also able to be transmitted to the front wheels through another transmission route, that is, from a hydraulic transmission which includes a hydraulic motor which is a continuously variable transmission connected to the front wheel differential gear. A front wheel acceleration dial, a front wheel acceleration ratio up switch 9 and a front wheel acceleration ratio down switch 9, for appropriately changing the front wheel drive speed during turning, or the like are connected to a controller which is related to front wheel acceleration steering control. Then, the acceleration ratio up/down switches 9, 9 are arranged integrally with a steering wheel 10 or the like so as to improve maneuverabilty thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning device for a working vehicle for agricultural use such as a tractor or a combine, construction or transportation of a bulldozer or the like.

[0002]

2. Description of the Related Art Conventionally, agricultural work vehicles such as tractors are:
It is configured to transmit the rotational power of the engine to the front wheels or crawler device via the traveling transmission device,
The rotation speed is increased or reduced during turning to facilitate turning in wet fields or the like.

[0003]

In the above-mentioned known work vehicle, a rotational speed based on a preset speed increase rate is transmitted to front wheels or crawlers in connection with a steering operation, for example, a turning angle of a steering handle. Thus, the turning time can be reduced. However, in a field or the like where these vehicles travel, there is a difference in the turning space depending on the location, and there is also a difference in the hardness of the soil and a difference in the degree of slipping, so that it is based on the speed increase rate initially set. There was a problem that it was not possible to make a cornering run suitable for the location only by driving the front wheels.

[0004]

SUMMARY OF THE INVENTION The present invention takes the following technical means in order to solve the above-mentioned problems. That is, in a working vehicle including a pair of left and right traveling devices 3 and 3 driven by the continuously variable transmission 7 and changing the transmission ratio of the continuously variable transmission 7 during a turning operation of the vehicle, a steering operation member of the vehicle is used. At 10 (11) or in the vicinity thereof, there is provided a turning device for a working vehicle, which is provided with operating tools 9, 9 'for changing the driving speed of the traveling devices 3, 3 at the time of turning.

According to a second aspect of the present invention, the steering operation member is constituted by a steering wheel 10 or a steering lever 11, and operating tools 9, 9 'for changing the driving speed of the traveling devices 3, 3 are used for increasing speed. , And a pair of switches for deceleration.

[0006]

Since the present invention is constructed as described above, according to the first aspect of the present invention, the transmission rate can be increased or decreased by the immediate judgment of the operator who actually performs the steering operation, and the turning point can be adjusted. The feature is that the vehicle can make a turning run suitable for the surrounding conditions. Further, since the operating tools 9 and 9 'of the first aspect of the present invention comprise a pair of switches for increasing the speed of the front wheels and for reducing the speed of the front wheels, the steering operation can be performed in comparison with the case of, for example, a dial type. There is an effect that the adjustment operation can be performed quickly while performing the adjustment.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case where an embodiment of the present invention is provided in an agricultural tractor will be described. Tractor T
As shown in FIG. 3, a pair of left and right front wheels 3 steered by a steering wheel 10, which is a steering operation unit, is provided at the front of the vehicle body.
And a pair of left and right rear wheels 4 is provided at the rear of the vehicle body. The engine 1 is mounted on an engine frame at the front of the vehicle body, is covered by a hood cover 15, and is configured to transmit rotational power to each transmission in the transmission case 2.

The cabin 14 is provided with a control seat 12 in the room, a front wheel speed-up dial 8 for setting a front wheel speed-up rate in advance on the side, and a wheel / crawler mode changeover switch 4.
1. The work implement elevating lever 31 and the like are arranged in a concentrated manner, and these setting devices are connected to a controller C which is a control means of the vehicle. As shown in FIG. 2, the transmission mechanism in the transmission case 2 is provided in the order of a main clutch device 16, a forward / reverse switching device 17, a main transmission device 18, and a subtransmission device 19 from the upper transmission side, The configuration is such that the rotational power input from the engine 1 is converted into rotation adapted to the speed change lever. The rear wheel 4 is connected to the sub-transmission 19.
Is transmitted through the rear wheel differential device 20, the wheel gear, and the wheel shaft in order to propel the tractor T. Each of the left and right wheel shafts is provided with a brake disk 21.

The front wheels 3 are driven by transmitting the rotational power reduced by the auxiliary transmission 19 via a front wheel transmission shaft 22 and a front wheel differential 23. In this manner, the tractor T is a four-wheel drive type in which the front wheel 3 and the rear wheel 4 drive the rear wheel 3 or the front and rear wheels 3, 4 with the rotational power output from the gear type transmissions 17, 18, 19. Is configured.

The front wheel 3 is a continuously variable transmission connected to a transmission path 6 different from the front wheel transmission shaft 22 connected to the gear type transmission, that is, a front wheel differential unit 23. 7 can be transmitted. And
As shown in FIG. 6, the hydraulic transmission 7 includes a conventionally known variable hydraulic pump 24 and a hydraulic motor 25, and the like.
The oil discharge amount is changed by an electric motor 34 which is an actuator for adjusting the angle of the swash plate in the pump 24, and the rotational power that is continuously changed from high speed to low speed is transmitted to the front wheel differential 23.

The hydraulic transmission 7 is configured to transmit rotational power at a preset speed or an adjusted speed to the front wheels 3 in association with the steering operation of the front wheels. It will be described later according to the description.
Reference numeral 26 in FIG. 2 indicates a one-way clutch, in which the rotation speed transmitted from the hydraulic transmission 7 via the transmission path 6 exceeds the rotation speed transmitted from the gear type transmission via the front wheel transmission 22. When this occurs, the power transmission is cut off. Reference numeral 39 in FIG. 6 denotes a switching control valve for turning on and off the operation of the hydraulic motor 25.

Next, a description will be given of a working machine lifting / lowering device of the tractor T with reference to FIG. The hydraulic cylinder 28 of the work machine elevating device is provided in the rear upper portion of the transmission case 2,
The lift arm 29 protruded to the outside of the case by the expansion and contraction of the piston is configured to be vertically rotated. The lift arm 29 is provided with a lift arm angle sensor 30 at the rotation base, and a working machine 27 (tiling device in the illustrated example) is suspended and connected via a link mechanism. It is configured to rotate up and down based on expansion and contraction sliding.

The work machine elevating lever 31 is operably connected to the cabin 14 and is provided with a potentiometer 32 for detecting an operation position at a pivot base thereof. The hydraulic cylinder 28 is driven so that the set angles of the lift arms 29 match. Here, the lifting device of the work machine 27 and its safety mechanism will be described.

As shown in FIG. 1, the controller C is connected to a position meter 32, a lift arm angle sensor 30, and a raising position setting dial 36 on the input side, and is connected to a rising pressure proportional control valve on the output side. A solenoid 37 and a solenoid 38 of a pressure proportional control valve for lowering are connected to each other. Then, the controller C
Can be raised to the position set in advance by the raising position setting dial 36, but as a safety mechanism, when the restart information of the engine 1 is input from the engine rotation sensor 35, the safety height is lowered to a safety height lower than the above set value. A configuration that can only ascend will ensure safety. In this case, the raising position setting dial 36 is once returned to “0” and reset.

As described above, the lifting device of the work machine 27
By taking the above-described safety measures, it is possible to prevent an accident such as an excessive rise when the work machine is replaced or the like, which breaks the rear window from the rear outside of the cabin 14 and breaks. Next, as described at the beginning of the “Embodiment of the present invention”, the front wheel 3 is operated by rotating a steering wheel 10 provided in a cabin 14 constituting the steering device 5, whereby a power steering mechanism (not shown) is provided. The front wheel 3 is operated via the. A steering angle sensor 33 is provided at a portion (the steering shaft in the figure) interlocked with the steering wheel 10 as means for detecting turning.

Next, the controller C will be described. First, the configuration related to the front wheel speed-up steering control will be described. The controller C has a CP inside as shown in FIG.
U, RAM, ROM, etc., on the input side, a front wheel speed-up dial 8, a front wheel speed-up switch for appropriately changing the drive speed of the front wheels 3 and 3 at the time of turning, and a front wheel speed-down switch 9 '; The cut angle sensor 33 and the like are connected. The electric motor 34, the liquid crystal monitor 42 and the like are connected to the output side. The electric motor 34 operates according to a control signal output from the controller C, that is, an output voltage, and adjusts the oil discharge amount of the variable hydraulic pump 24 constituting the hydraulic transmission 7 described above. I have.

The ROM of the controller C stores a preset control mode, various kinds of reference data, a control program, and the like. The front wheel speed-increasing dial 8 sets in advance a speed-increasing rate of the front wheel 3 during turning (a peripheral speed ratio of the front wheel 3 in comparison with a peripheral speed "1" of the rear wheel 4), and inputs and stores it in the controller C. It is a vessel. The front wheel speed-up switch 9 and the front wheel speed-down switch 9 'are switches for adjusting the front wheel speed-up dial setting device 8 to appropriately increase or decrease the speed-up ratio of the front wheel 3 during turning, which is set in advance. Each time the button is pressed, the rate of increase can be changed at a fixed rate, for example, ± 0.1.

The above-mentioned front wheel speed increase rate switch 9
The front wheel speed increase rate down switch 9 'is disposed at the center of the steering wheel 10, as shown in FIG. In the case where the steering member of the vehicle is constituted by a lever 11 type, switches 9 and 9 'are provided above the lever holding portion as shown in FIG. I do.

Next, the steering angle sensor 33 detects the steering angle of the steering wheel 10 and inputs it to the controller C. Then, the controller C compares the information input from the steering angle sensor 33 with reference information stored in advance, determines whether the angle is such that a turning operation can be assumed, and outputs a control signal. It is configured to output.

As a method for detecting the turning operation, a structure for detecting the front wheel steering amount of the tractor T or a structure for detecting the angular velocity may be employed. When the tractor T configured as described above starts turning, the tractor T receives a hydraulic speed change via the electric motor 34 based on a preset speed increase rate or a speed increase rate that is adjusted as described later. A front wheel speed-up steering control device that drives the device 7 to speed up and transmit the front wheels 3 is configured.

Here, a safety device necessary for safely controlling and operating the above-described front wheel speed increasing control device will be described.
First, as shown in FIG. 1, the controller C is configured to connect an engine rotation sensor 35 to an input side and to input start and stop of the engine 1 as detection information. When the engine 1 is stopped once and restarted, the controller C always returns the speed increase rate of the front wheels 3 set by the front wheel speed increasing dial 8 to 0. When the dial 8 is operated again,
That is, when the detected value fluctuates, the front wheel speed increase control at the time of turning is activated.

Further, as another form of the safety device, a configuration may be employed in which the above-described front wheel speed increasing control device is turned off by operating a safety circuit in connection with engine start. In any case, when restarting (restarting the stopped engine 1), the operator uses the front wheel speed-up dial 8 to set the speed increase rate of the front wheels 3 again, and starts traveling.

As described above, the safety device is provided in a tractor equipped with a control device that turns the vehicle by turning the front wheel 3 at an increased speed.
It is indispensable to prevent the operator from forgetting to turn off the switch or runaway due to other erroneous operations. Next, a case where the rear wheel 4 is changed from a normal wheel type to a crawler type will be described.

Usually, the rear wheel 4 is changed from a wheel type to a crawler 4.
When the specification is changed to 0, the traveling transmission device 2
Must be changed to a transmission mechanism for low-speed transmission. Therefore, in the present embodiment, the front wheel 3 is provided with a simple configuration in which the front wheel 3 is transmitted at a low speed by a transmission path 6 different from the gear type transmission, that is, a hydraulic transmission 7 by using the front wheel speed increasing device. is there.

As shown in FIG. 1, the controller C has a wheel / crawler mode changeover switch 4 on its input side.
1 is connected to switch the mode.
Then, as shown in FIG. 7, the tractor T can travel by switching the wheel / crawler mode changeover switch 41 to the crawler mode side when the rear wheel 4 is removed and the crawler 40 is mounted and the specification is changed. It has a configuration that allows it.

Therefore, the tractor T outputs a control signal from the controller C to the electric motor 34 to transmit the hydraulic transmission at a low speed suitable for crawler traveling (for example, when the vehicle is traveling straight, the front wheel speed increase rate is 0.7 times that of the wheel). 7 to the front wheel 3 via the transmission path 6. As described above, by changing the specification of the rear wheel 4 to the crawler 40, the tractor T exhibits a function unique to the crawler, prevents subsidence in wetlands and the like, and has a sufficient propulsive force to efficiently work. Can do it.

Next, the operation will be described. First,
When performing the tilling work in the field, after the engine 1 is started, the controller C is started up to prepare for the operation state. Then, the tractor T lowers the work implement 27 to a predetermined tilling height, and moves forward while rotating to start tilling work. At this time, the tractor T receives the rotational power of the engine 1 into the transmission case 2 and
, The rear wheel 4 is driven from the forward / reverse switching device 17, the main transmission device 18, and the auxiliary transmission device 19 via the rear wheel differential device 20, while the rotational power reaching the front wheel transmission device 22 is the front wheel differential. The front wheel 3 is driven via the moving device 23.

As described above, the tractor T works while being propelled in the field by four-wheel drive. Next, the control operation of the front wheel speed increasing control device will be described with reference to the block diagram of the control mechanism of FIG. 1 and the control operation flowchart of FIG. Controller C
When the engine is started and the power supply system is started, reading is first performed from sensors and switches. And
The state of the wheel / crawler mode switch 41 is determined. When the switch state is the "crawler mode", the front wheel speed increase rate when the vehicle is traveling straight ahead is stored as 0 to 7 times, and a control signal is output to the electric motor 34 based on the speed increase rate. Thus, the traveling speed of the tractor T is transmitted to the front wheels 3 from the hydraulic transmission 7 via the transmission path 6 by the crawler 40 and travels strongly by the crawler 40. The one-way clutch 26
, The power transmission state is forcibly maintained in an “off” state by an actuator (not shown).

Next, when the changeover switch 41 is in the "wheel mode", the controller C operates the front wheel speed-up dial 8
Is read and stored in the RAM, and the vehicle travels. In this case, the tractor T continues to travel forward in the four-wheel drive state transmitted from the gear type transmission. And
When the tractor T reaches the turning point at the end of the field, the tractor T steers the steering wheel 10 to move to turning.
At this time, the steering angle is input from the steering angle sensor 33 to the controller C.

Then, when the controller C compares the input information with the previously stored turning angle and determines that the turning operation is performed, the controller C sends a control signal based on the set speed increase rate to the electric motor 34. Output. In this way, the tractor T receives the rotational power from the hydraulic transmission 7 that has been shifted to the speed increase rate based on the control signal via the transmission path 6 and the front wheels 3.
And the turning time is shortened. The tractor T presses rear wheel brake disks 21..
If the brake is applied, further turning is possible.

When an ON signal of the front wheel speed-up rate up switch 9 or the front wheel speed-up rate down switch 9 'is input during such turning, the amount of power to the electric motor 34 is reduced accordingly. The electric motor 34 changes the discharge amount of the pump 24 to change the drive speed of the front wheels 3. Further, the liquid crystal monitor 42 displays the front wheel speed increase ratio currently being output.

In this manner, the speed increase rate of the front wheels can be adjusted to increase or decrease by the immediate judgment of the operator who is actually performing the steering operation, and the vehicle can turn in a manner suitable for the surrounding conditions of the turning place.
Further, since these acceleration / deceleration switches 9, 9 'are arranged at the center of rotation of the steering handle 10, the operator can operate the vehicle while checking the turning state of the vehicle. Operability is better than that.

In the above-described embodiment, a so-called semi-crawler type tractor in which the front wheels are of a wheel type and the rear wheels are of a crawler type has been described. In this case HS
The drive speed of the left and right crawlers is changed by a continuously variable transmission such as T. An operating tool for changing the transmission ratio of the hydraulic transmission 7 utilizes a lever 41 provided near the steering handle 10 in FIG. 4, and adjusts the transmission ratio each time the lever 41 is operated in the up-down direction. It is good also as composition.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a connection state of a controller.

FIG. 2 is a transmission mechanism diagram of a tractor.

FIG. 3 is an overall side view of the tractor.

FIG. 4 is a plan view of a steering handle.

FIG. 5 is a perspective view of a steering lever.

FIG. 6 is a hydraulic circuit diagram.

FIG. 7 is a side view of the tractor when the crawler is mounted.

FIG. 8 is a flowchart showing an outline of a control program.

[Explanation of symbols]

 Reference Signs List 3 front wheel 4 rear wheel 7 hydraulic transmission 9 front wheel speed-up switch 9 'front wheel deceleration switch 10 steering wheel 11 steering lever

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D043 AA03 AB07 AB12 EA02 EA11 EA19 EA35 EA38 EA41 EA43 EB03 EB06 EB07 EB14 EE02 EE03 EE12 EF02 EF09 EF30

Claims (2)

[Claims] 1. A work vehicle comprising a pair of left and right traveling devices 3 and 3 driven by a continuously variable transmission 7, wherein the transmission ratio of the continuously variable transmission 7 is changed during a turning operation of the vehicle.
A turning device for a working vehicle, comprising operating tools 9 and 9 'for changing the driving speed of the traveling devices 3 and 3 at the time of turning, or at or near the steering operating member 10 (11) of the vehicle. . The steering operation member is a steering wheel 1.
An operating tool (9, 9 ') configured to change the driving speed of the traveling device (3, 3) to zero or a steering lever (11) type comprises a pair of speed increasing and decelerating switches. The turning device for a work vehicle according to claim 1.