JPH1053043A - Four-wheel drive type working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically select a wheel drive state best suited to a traveling state by switching to a travel mode of a two-wheel drive state at the time of detecting travel load to be close to a level ground travel load range, and switching to a travel mode of a four-wheel drive state at the time of detecting high load larger than a load range. SOLUTION: A control system of a transmission clutch 10 is composed of a travel mode selector, a solenoid valve, a travel speed sensor, and the like. The travel mode selector selects one of a two-wheel drive mode, a four-wheel drive mode and an automatic mode. When the two-wheel drive mode is selected, the solenoid valve is operated so as to put the transmission clutch no in an off state to obtain a two-wheel drive state, and when the four-wheel drive mode is selected, the solenoid valve is operated so as to put the transmission clutch 10 in an on state to obtain a four-wheel drive state. A drive state can thereby be switched automatically into the four-wheel drive state of driving both front wheels 2 and rear wheels 3, and into a two-wheel drive state of cutting off transmission to the front wheels so as to drive only the rear wheels 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive type working vehicle such as an agricultural tractor.

[0002]

2. Description of the Related Art In four-wheel drive agricultural tractors,
By turning on and off a transmission clutch provided in a transmission system to a steered wheel (generally, a front wheel), a four-wheel drive state or a two-wheel drive state can be switched and selected according to a traveling state. It has also been studied to automatically perform the above switching. For example, in Japanese Patent Application Laid-Open No. 2-246876, a four-wheel drive state in which a working device such as a tilling device connected to an airframe is lowered to a working position is set. There is disclosed an apparatus in which when a working device is raised to a non-working position, the working device is automatically switched to a two-wheel drive state.

[0003]

According to the above-mentioned conventional means, when the working device is raised to the non-working position in order to change the body direction at the ridge or the like, the state is automatically switched to the two-wheel drive state, This makes it possible to turn the steered wheels smoothly and to make a sharp turn of the aircraft, which is effective in improving the maneuverability on the ridge. Further, when traveling on the road, the working device is raised to the non-working position, so that the vehicle is in a two-wheel drive state, so that there is an advantage that the steering becomes easy. However, there were problems in the following points. Since the vehicle is in a two-wheel drive state when traveling on the road, there is insufficient thrust when climbing a slope, and it is necessary to manually switch to a four-wheel drive state, and there is room for improvement in handling.

The present invention has been made by paying attention to such a point. When a vehicle is traveling on a road, a wheel drive mode suitable for a traveling condition is automatically selected, so that traveling on the road is reduced. The purpose is to be able to do.

[0005]

[Means for Solving the Problems]

 [Configuration, operation and effect of the invention according to claim 1]

(Structure) In the four-wheel drive type working vehicle according to the first aspect of the present invention, a transmission clutch provided in a transmission system to the steered wheels and a traveling load detecting means are linked, and the traveling load is on a flat ground on a road. When it is detected that the vehicle is near the traveling load range, the transmission clutch is disengaged and switched to the two-wheel drive state, and when it is detected that the load becomes higher than the load range, the transmission clutch is engaged and activated. And a driving mode switching control means for switching to a four-wheel drive state.

(Operation) According to the above configuration, when traveling on a road, the traveling load when traveling on an ordinary flat ground is close to the range of the flat road running load, so that a two-wheel drive state is brought about and light steering is performed. In addition to this, when the traveling load on the uphill reaches a large value exceeding the level load traveling range, a four-wheel drive state is brought about, and the uphill traveling can be reliably performed with a large propulsive force. In addition, even when traveling on a flat ground or a place where a traveling load is large, such as a mud or a wetland, the vehicle can surely travel in a four-wheel drive state that provides a large propulsive force. In addition, as means for performing flat road traveling in a two-wheel drive state and climbing traveling in a four-wheel drive state, means for automatically switching the traveling mode by detecting the inclination of the aircraft can be considered, but in flat muddy or wetland, Automatic switching to the four-wheel drive state is not performed, and artificial driving mode switching is required.

(Effects) As described above, according to the first aspect of the present invention, a suitable wheel driving state according to the driving situation is automatically selected, and a troublesome operation of selecting the wheel driving mode by the driver is performed. It is now possible to run smoothly on the road without need.

[Structure, operation and effect of the invention according to claim 2]

(Structure) In the four-wheel drive type working vehicle according to the second aspect of the present invention, it is detected that the traveling load has become lower than the flat-land traveling load range in the first aspect of the invention. And the traveling mode switching control means is configured to engage the transmission clutch to switch to a four-wheel drive state.

(Operation) According to the above configuration, a two-wheel drive state is provided during traveling on level ground, a four-wheel drive state is provided during uphill traveling, and a four-wheel drive state is provided during downhill traveling where traveling load is greatly reduced. Brought. In the four-wheel drive state, the engine brake works on all four wheels, so you can drive downhill safely.

(Effects) Therefore, according to the invention of claim 2, an appropriate traveling mode is automatically selected according to various situations during traveling on the road, and the vehicle can travel smoothly and safely.

[Structure, operation and effect of the invention according to claim 3]

(Structure) In the four-wheel drive type working vehicle according to the third aspect of the present invention, in the first or second aspect of the present invention, the traveling load detecting means may include a displacement of a fuel adjusting member in an electronic governor provided in the mounted engine. Is detected.

(Operation) In a work vehicle, it is desired to stabilize the engine speed irrespective of load fluctuations. Therefore, a governor having a characteristic of exhibiting a speed control function over the entire speed range, that is, a so-called all-speed governor is used. ing. In this all-speed governor, in order to stabilize the engine speed, when the load increases and the number of engines decreases, the amount of fuel supplied increases, and conversely, the load decreases and the number of engines increases. Since the fuel adjusting member operates so as to reduce the fuel supply amount, the displacement of the fuel adjusting member can be regarded as a load change. In the electronic governor, control is performed to detect and feed back the actual fuel adjustment amount in order to bring the actual fuel adjustment amount closer to the target fuel adjustment amount determined based on the load variation.
For this purpose, the displacement of the fuel adjusting member is detected. Here, the detected feedback signal can be used as a load signal.

(Effects) Therefore, according to the third aspect of the present invention, the displacement detecting means of the fuel adjustment member originally provided in the electronic governor can be used as the traveling load detecting means. In addition to exhibiting the above effects of any one of the inventions, there is an advantage that the invention can be implemented at low cost without preparing dedicated traveling load detecting means.

[Structure, operation and effect of the invention according to claim 4]

(Structure) In the four-wheel drive working vehicle according to the fourth aspect of the invention, a rolling sensor for detecting a lateral inclination of the body is linked to a transmission clutch provided in a transmission system to steered wheels. When the vehicle body rolling is small, the transmission clutch is disengaged to switch to the two-wheel drive state, and when the vehicle body rolling is large, the transmission clutch is engaged and operated to switch to the four-wheel drive state. And

(Operation) According to the above configuration, when the vehicle is traveling on a relatively flat place while traveling on the road, the body is in a two-wheel drive state because the rolling of the body is small, so that the vehicle can be steered lightly. You can run. Further, when the vehicle rolls on a rough road and becomes large, the vehicle is switched to the four-wheel drive state, and the vehicle can run with strong propulsion.

(Effects) Therefore, according to the fourth aspect of the present invention, a suitable wheel driving state according to the rough running condition of the road surface is automatically selected, and the driver is troublesome in selecting the wheel driving mode. It has become possible to run on the road smoothly without any operation.

[Structure, operation and effect of the invention according to claim 5]

(Structure) In the four-wheel drive working vehicle according to the fifth aspect of the present invention, in any one of the first to fourth aspects of the invention, the working device mounted so as to be vertically movable is raised to a non-working height. In this case, the operation of the driving mode switching control means is performed.

(Operation) Since the working device is raised to the non-working height when traveling on the road, when the working device is lowered and the working traveling is performed, the traveling mode is automatically switched in accordance with the machine body rolling. Never.

(Effects) Therefore, according to the invention of claim 5, the automatic switching operation of the traveling mode according to the fluctuation of the traveling load or the body rolling is performed only during traveling on the road. The above-mentioned effect of any one of the inventions according to any one of Items 1 to 4,
It is possible to avoid a situation in which two-wheel drive is inadvertently performed during work that often travels with four-wheel drive and the driving force becomes insufficient, and the practical convenience is high.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an agricultural tractor will be described below with reference to the drawings. As shown in FIG. 1, the agricultural tractor according to this embodiment includes a working device 4 such as a rotary tilling device at a rear portion of an airframe 1 having a front wheel 2 as a steering wheel and a rear wheel 3 as a main propulsion wheel. Drive up and down freely via the three-point link mechanism 5,
In addition, it has a structure in which drive rolling is freely connected.
It is possible to artificially or automatically switch between a four-wheel drive state in which the front wheel 2 and the rear wheel 3 are driven together, and a two-wheel drive state in which the transmission to the front wheel 2 is interrupted to drive only the rear wheel 3. It has become.

FIG. 2 schematically shows a transmission system, in which an output from an engine 6 mounted on a front portion of the body 1 is transmitted to a transmission case 8 via a main clutch 7 where an appropriate transmission (shown in FIG. 2) is used. ) Is transmitted to the rear differential mechanism 9, and the left and right rear wheels 3 are driven. Further, the final shifted power is transmitted by a transmission clutch 1 having a multi-plate hydraulic clutch structure.
0 and transmitted to the front differential machine 11 through the left and right front wheels 2
The transmission clutch 10
Is controlled by a solenoid valve 12 to be described later.

As the engine 6, a diesel engine is used, and as shown in FIG. 3, the governor 13 is constituted by an electronic governor. The electronic governor is the fuel injection pump 1
The control rack 15 serving as a fuel adjusting member is operated to be displaced by a solenoid 16, and the position of the control rack 15 is detected by a displacement sensor 17 such as a differential transformer. Also,
The actual engine speed is detected by an engine speed sensor 19, which is an electromagnetic pickup sensor disposed opposite to a gear 18a provided on a cam shaft 18 for driving the fuel injection pump 14, and further, as shown in FIG. , Airframe 1
Has a rolling sensor 20 for detecting the inclination angle in the left-right direction.
Is provided.

FIG. 4 shows the control of the electronic governor 13 and
FIG. 2 is a block diagram of a traveling mode switching control unit that switches the traveling mode between a four-wheel drive state and a two-wheel drive state by turning on and off the transmission clutch 10.

In FIG. 4, reference numeral 21 denotes a control device using a microcomputer, 22 denotes an engine speed setting device, 2
Reference numeral 3 denotes a hand accelerator lever for operating the engine speed setting device 22. When the engine speed is set by the engine speed setting device 22, a torque curve having characteristics previously stored and set corresponding to the set speed is set. Along with this, a target control rack position is calculated in accordance with a change in the engine speed detected by the engine speed sensor 19, and the solenoid 16 is energized so as to displace the control rack 15 toward the target control rack position. It is supposed to be.

The control system of the transmission clutch 10 includes a traveling mode selector 24, the solenoid valve 12, a traveling speed sensor 25,
And so on. The traveling mode selector 24 can select any one of “two-wheel drive mode”, “four-wheel drive mode” and “automatic mode”, and when the “two-wheel drive mode” is selected, the transmission clutch 10 is in the “disengaged” state. When the "four-wheel drive mode" is selected, the solenoid valve 12 is operated so that the transmission clutch 10 is in the "on" state, and the four-wheel drive state is established. Becomes The traveling speed sensor 25 is configured as an electromagnetic pickup sensor that detects the rotation speed in the transmission system that has been finally shifted.

Next, the control operation of the driving mode switching control means will be described with reference to the flowchart of FIG. First,
The traveling mode selection state of the traveling mode selector 24 is determined (# 1), and when it is confirmed that the "two-wheel drive mode" or the "four-wheel drive mode" is selected, traveling in the corresponding traveling mode is performed. Is executed. When the "automatic mode" is selected, the process proceeds to the next step, and it is determined whether or not the working device 4 has been raised to the non-working height (#
2). The height of the working device 4 is determined based on information from a potentiometer 26 provided at the base of the three-point link mechanism.

Here, if the working device 4 is not raised to the non-working height, it is determined that the vehicle is in the work traveling state, and the four-wheel drive state is brought about.

If the working device 4 has been raised to the non-working height, the process proceeds to the next step, where the traveling speed is determined (# 3). Here, the set speed V1 (for example, 7) where the traveling speed V is slightly higher than the work traveling speed in the field (tiling work speed).
If the speed is lower than 〜8 km / h), it is determined that the vehicle is traveling in the field, and a four-wheel drive state is provided. On the other hand, if the traveling speed V is higher than the set speed V1, it is determined that the vehicle is traveling on the road, and the process proceeds to the next step to determine the traveling load (#).
4).

Here, the detected traveling load L is compared with a set value L1 which is larger than an average traveling load range when traveling on level ground, and when the traveling load L is larger than the set value L1, traveling on an uphill is performed. And a four-wheel drive state is provided. If the running load L is less than the set value L1, it is determined that the vehicle is not traveling uphill, and the process proceeds to the next step to further determine the running load (# 5). Here, the detected traveling load L is compared with a set value L2 which is considerably smaller than an average traveling load range when traveling on a level ground, and when the traveling load L is equal to or less than the set value L2, the vehicle goes downhill. When it is determined that the vehicle is traveling, a four-wheel drive state is provided, and the traveling load L
Is larger than the set value L2, it is determined that the vehicle is traveling on normal flat ground, and the process proceeds to the next step, where the state of the body rolling is determined (# 6).

Here, the result of the detection by the rolling sensor 20 is to be determined, and when the fluctuation of the body rolling is large, it is determined that the vehicle is traveling on a rough road, and a four-wheel drive state is brought about. Further, when the fluctuation of the body rolling is small, it is determined that the vehicle is traveling on a normal road, and a two-wheel drive state is brought about.

Note that the rolling sensor 20 is also used for rolling control of the working device 4. The rolling control of the working device 4 is configured so that the working device 4 can be always kept horizontal irrespective of the rolling of the machine body 1 by performing rolling adjustment of the working device 4 in the opposite direction by the same angle as the machine body inclination angle. Things.

[Other Embodiments] In the above embodiment, the case where the automatic switching control of the traveling mode is performed based on the traveling load and the body rolling is exemplified. However, the traveling mode is controlled only based on the traveling load or the body rolling. It is also possible to carry out in a mode in which automatic switching control is performed. Further, the present invention can be applied not only to a farm tractor but also to a four-wheel drive lawn mower in which a mower as a working device is connected to be able to move up and down.

[Brief description of the drawings]

FIG. 1 is an overall side view of an agricultural tractor.

FIG. 2 is a schematic diagram of a transmission system.

FIG. 3 is a side view of the electronic governor.

FIG. 4 is a control block diagram.

FIG. 5 is a control flowchart.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Airframe 2 Steering wheel (front wheel) 4 Working device 6 Engine 10 Transmission clutch 13 Electronic governor 15 Fuel adjustment member

Claims (5)

[Claims] A transmission clutch provided in a transmission system to a steered wheel and a traveling load detecting means are linked, and when it is detected that the traveling load is near a level road traveling load range on a road, the transmission clutch is activated. A running mode switching control means is provided for switching to a two-wheel drive state by disengagement operation, and when it is detected that the load becomes higher than the load range, the transmission clutch is engaged and operated to switch to a four-wheel drive state. Four-wheel drive work vehicle. 2. When the running load is detected to be lower than the level running load range, the driving mode is switched to the four-wheel drive state by switching on the transmission clutch. The four-wheel drive work vehicle according to claim 1, wherein 3. The four-wheel drive work vehicle according to claim 1, wherein the traveling load detecting means detects a displacement of a fuel adjusting member of an electronic governor in the mounted engine. 4. A rolling sensor for detecting a lateral inclination of the fuselage is linked with a transmission clutch provided in a transmission system to the steered wheels, and when the rolling of the fuselage is small, the transmission clutch is disengaged to perform a two-wheel drive state. A four-wheel drive type work vehicle comprising a traveling mode switching control means for switching to the four-wheel drive state by engaging and operating the transmission clutch when the body rolling is large. 5. The method according to claim 1, wherein the operation of the traveling mode switching control means is performed when the working device mounted so as to be able to move up and down is raised to a non-working height. The four-wheel drive work vehicle according to one of the above.