JPH026230A - Working vehicle - Google Patents

Abstract

PURPOSE:To prevent the damage of a speed change system and others even if the running direction is reversed during running by switching from 4th drive state to 2nd drive state when an operation to reverse the running direction is conducted. CONSTITUTION:A forward/reverse gear shifter 3 has a friction type clutch for forwarding 3b and a gear transmission system for reversing 3c, and a pressure oil from a cut-off solenoid valve 10 is selectively supplied to one of the two hydraulic clutches 3a, 3b. A mode switching clutch 7 is also provided with a friction type hydraulic clutch therein and sets the running mode to 4th drive state by supplying the pressure oil and to 2nd drive state by exhausting the oil. The forward/reverse gear shifter 3 and the cut-off solenoid valve 10 are combined together to form a forward/reverse switching mechanism A, and the mode switching clutch 7 and a mode solenoid valve 11 are combined together to form a drive mode selecting mechanism B.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a work vehicle, and more specifically, the present invention relates to a work vehicle that can select between traveling by two-wheel drive and traveling by four-wheel drive, and can switch between forward and backward travel. This invention relates to control technology for a work vehicle configured as described above.

[Conventional technology]

Taking an agricultural tractor as an example of a work vehicle, conventional agricultural tractors can select between a 2WD state in which only the rear wheels are driven and a 4WD state in which each of the front and rear wheels are driven, and can switch between forward and backward movement. There is something that is configured like this,
Furthermore, there are some recent agricultural tractors that have a dedicated operating lever or the like for switching only between forward and backward movement (references not listed).

[Problem to be solved by the invention]

In addition, as mentioned above, in a work vehicle that can select between 2WD and 4WD, for example, a shovel is attached to the front of the vehicle.
When performing work such as moving earth and sand, the 4WD mode, which allows powerful driving, is selected.

However, in operations such as moving earth and sand, the direction of movement of the car body is often changed back and forth. Despite the fact that the vehicle is supposed to start traveling, operations are often performed to reverse the traveling direction while the vehicle is still running, and when such an operation is performed, the The reaction force may damage the transmission system, etc.

In particular, vehicles that have a dedicated lever for switching between forward and backward movement of the vehicle body are easy to operate and are likely to cause the above-mentioned inconvenience, and vehicles that can switch between 2WD and 4WD conditions are Since the grip force of the wheels on the ground in 4-wheel drive mode is greater than the grip force of the wheels on the ground in 2-wheel drive mode, the above-mentioned problems are likely to occur when working in 4-wheel drive mode, and there is room for improvement. .

An object of the present invention is to construct a working vehicle through rational modification that causes as little damage to the transmission system as possible even when the traveling direction is reversed while the vehicle body is still running.

[Failure to solve the problem]

The present invention is characterized by a four-wheel drive state in which the front and rear wheels are driven simultaneously;
Alternatively, drive only one of the front and rear wheels.
The vehicle is equipped with a drive mode selection mechanism that can set the driving system to one of the driving states, and a forward/reverse switching mechanism that sets the running direction of the vehicle body to either front or rear.
When driving in 4WD mode, when an operation is performed to reverse the driving direction, priority is given to the setting of the drive mode selection mechanism, and at the timing when the forward/reverse switching mechanism reaches a substantially neutral state,
The present invention includes a control means for setting the running system in a 2-wheel drive state and restoring it to a 4-wheel drive state after a predetermined period of time has elapsed, and its functions and effects are as follows.

[For production]

If the above characteristics are configured as shown in FIG. 1, for example, when an operation is performed to reverse the running direction while driving,
As shown in the flowchart in the figure, when the driving mode is set to 4WD, the switching solenoid valve (10
) When the driving system reaches a substantially neutral state, set the driving mode to 2WD (2WD), and after reversing the driving direction, change the driving mode to 4WD (41SD). Set to .

In other words, when reversing the running direction, the 2-drive state (2
By temporarily switching the driving mode to WD), the blip force of the wheels against the ground is weakened and the occurrence of slip is promoted, thereby making it possible to reduce the reaction force from the driving system.

〔Effect of the invention〕

Therefore, when an operation is performed to reverse the running direction,
By modifying the vehicle by adding a control means to switch from 4WD to 2WD, a work vehicle was constructed that would cause less damage to the transmission system, etc., even if the direction of travel was reversed while the vehicle was still moving. .

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Figure 1 shows an overview of the running transmission system and control system of an agricultural tractor as an example of a working vehicle. The power from the forward/reverse transmission (3) is transmitted to the forward/reverse transmission (3), and after being shifted by the main transmission (4), the power is transmitted to the differential (5a) of the rear wheels (5) and the gears. Transmission mechanism (6), mode switching clutch (7), transmission shaft (8)
) are transmitted to the differential device (9a) of the front wheels (9), respectively, and also control the switching solenoid valve (10) that controls the forward/reverse transmission mechanism (3) and the mode switching clutch (7). A mode solenoid valve (11) is provided.

Incidentally, the forward/reverse transmission (3) has a forward friction type clutch (3b) and a reverse gear transmission system (3c), and the pressure oil from the switching solenoid valve (10) is transmitted through them. It is selectively supplied to one of the two hydraulic clutches (3a) and (3b), and the mode switching clutch (7) is also equipped with a friction-type hydraulic clutch (not shown), and is controlled by supplying pressure oil. Change to 4WD state, change to 2WD state by draining oil, and set driving mode.

The forward/reverse transmission (3) and the switching solenoid valve (10) are collectively referred to as a forward/reverse switching mechanism (A), and the mode switching clutch (7) and mode solenoid valve (11) are collectively referred to as a drive mode selection mechanism. It is called mechanism (B).

In this agricultural tractor, when an operation is performed to reverse the running direction while maintaining the running state, if the running mode is 4WD, the forward/reverse switching mechanism (A) reaches a substantially neutral state. At the same timing, switch the driving mode to 2WD (2WD) and start the transmission system, especially the hydraulic clutches (3a) and (3b) of the forward/reverse transmission (3).
The vehicle is equipped with a control device (12) (an example of a control means) for reducing the reaction force from the driving system against the vehicle and restoring the driving mode to a 4WD state after a predetermined period of time has elapsed.

That is, the control device (12) includes a microprocessor (not shown), and the control device (12) includes a changeover switch (13) for setting the traveling direction to forward or reverse.
A signal from a pick-up type speed sensor (14) that measures the rotational speed of the gear transmission mechanism (6) to detect the traveling speed is input, and the switching solenoid valve (10) and the mode solenoid valve (11) ), a signal system is formed to output a signal to each of them, and operates according to the flowchart shown in FIG.

For the operation of the control device (12), first the changeover switch (13
) and determines that the switching operation has been performed (#1.32 Stebka, the signal from the speed sensor (14) indicates that the vehicle is traveling at a predetermined speed (approximately 15 km/h) or higher. If it is determined (#3, #4 step, it is determined whether the driving mode is set to 4WD (#5)

When it is determined in step #5 that the driving mode is in the 4WD state, the switching solenoid valve (10) is operated in the neutral direction, the mode switching valve (11) is operated in the 2WD state (2WD) position, and the timer is activated. (formed in the software system by the program) and operate the switching solenoid valve (10) to the side set by the switching switch (13) (#6 to #1
0 stave force.

Then, when the timer detects that a predetermined period of time (about a few seconds) has elapsed, the mode solenoid valve (11) is switched to the 4WD state (4WD state).
WD)) (#10.311
sticker.

In addition, if it is determined in step #4 that the speed is below the predetermined speed, and if it is determined that the speed is in 2WD in step #5, the direction of travel is reversed by continuous operation of the switching solenoid valve (10). (#12.#13 sticker.

[Another example]

The present invention can be implemented in various ways other than the above-mentioned embodiments (for example, the control means may be configured as hardware by combining logic gates, comparators, timers, etc., and may be applied to an agricultural vehicle as a working vehicle). .

Further, in the present invention, a structure for setting a predetermined time for maintaining the changed state of the drive mode may be mechanically configured.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of a working vehicle according to the present invention, with FIG. 1 being a diagram showing a transmission system and a hydraulic system, and FIG. 2 being a flowchart showing the operation of a control device. (5)... Rear wheel, (9)... Front wheel, (12)... Control means, (A)...
Forward/forward switching mechanism, (B)...Drive mode selection mechanism.

Claims (1)

[Claims] 4WD state where front and rear wheels (9) and (5) are driven simultaneously;
Alternatively, a drive mode selection mechanism (B) that can set the running system to one of the 2WD states in which only one of the front and rear wheels (9) and (5) is driven; A forward/reverse switching mechanism that can be set to either the front or rear (
A) is provided, and when an operation is performed to reverse the driving direction while driving in 4WD mode, the forward/reverse switching mechanism (A) takes priority over the setting of the drive mode selection mechanism (B) and changes to approximately neutral mode. A work vehicle is provided with a control means (12) for setting a traveling system to a 2-wheel-drive state at the timing when the state is reached, and restoring it to a 4-wheel-drive state after a predetermined period of time has elapsed.