JP3641546B2 - Work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a drive type left and right front wheels configured to be steerable, a drive type left and right rear wheels, and a braking device for independently braking the left and right rear wheels. A work vehicle equipped with a control means that increases the peripheral speed of the front wheel in conjunction with the steering operation and that controls the braking device on the inner side of the turn. The present invention relates to a technique for preventing turning at a radius.
[0002]
[Prior art]
As a work vehicle configured as described above, there is a work vehicle disclosed in Japanese Patent Laid-Open No. 7-125553. In this conventional example, a vehicle speed sensor of a Doppler type that detects a traveling speed is provided in the lower body of the vehicle body. Only when the steering operation is performed in a state where the traveling speed measured in (2) is low, the controller performs acceleration of the front wheel and braking of the rear wheel inside the turn.
[0003]
[Problems to be solved by the invention]
Here, considering the above-described conventional example, in this conventional example, stable traveling is enabled by preventing acceleration of the front wheels and braking of the rear wheels inside the turn during high-speed traveling. Yes. However, since a Doppler type vehicle speed sensor is used, the unevenness of the ground surface and the vibration of the vehicle body may affect the detection accuracy, so there is room for improvement. Therefore, it may be possible to determine the running speed of the vehicle body by measuring the rotational speed of the transmission shaft in the mission case or axle case with a sensor such as a pickup type, but the mission case or axle case is filled with oil. Since the transmission shaft is located further inward than the wall surface of the transmission case or axle case, the arrangement structure of the sensor is likely to be complicated and the maintenance of the sensor becomes difficult, and there is room for improvement.
[0004]
An object of the present invention is to rationally configure a work vehicle that can accurately measure the traveling speed of a vehicle body with a simple structure and prevent acceleration of a front wheel and braking of a rear wheel inside a turn during high speed traveling. In the point.
[0005]
[Means for Solving the Problems]
The first feature of the present invention (Claim 1) is, as described at the beginning, drive type left and right front wheels configured to be steerable, drive type left and right rear wheels, and left and right rear wheels. And a braking device for independently braking the rotary tiller device to the rear of the vehicle body,
In conjunction with the steering operation of the front wheel, the peripheral speed of the front wheel is increased from the peripheral speed of the rear wheel, the braking device on the inner side of the turn is braked, and the rotary tillage device is raised. In a work vehicle equipped with a control means,
A speed determining means for determining a traveling speed of the vehicle body from a speed change position of a transmission device provided in the vehicle body and an actual rotational speed of the engine measured by the rotation speed sensor ; Prepared,
When the traveling speed discriminated by the speed discriminating means is equal to or higher than the set value, the front wheel speed increasing state, the braking device braking state, and the rotary tiller are prevented from being restrained. A blocking means to
When the actual rotational speed of the engine determined by the rotational speed sensor is less than a set value, the speed increase state of the front wheels, the braking state of the braking device, and the rotary tillage device rise Is provided with a sub-blocking means for checking and blocking, and its operation and effect are as follows.
[0006]
A second feature of the present invention (Claim 2) is that in Claim 1, the speed of the front wheel is increased in accordance with detection when the traveling speed is equal to or higher than the set value or when the engine speed is lower than the set value. A mode for inhibiting the appearance of the state, the appearance of the braking state of the braking device, and the raising of the rotary tiller,
When the running speed is equal to or more than the set value and, irrespective of the detection when the engine rotational speed is less than the set value, to the mode that does not perform the check blocking, in that Ru Oh provided switching operation possible mode switch There are the following actions and effects.
[0007]
[Action]
According to the first feature, since the speed determining means determines the traveling speed of the vehicle body based on the shift position of the transmission and the engine rotation speed, the influence of the unevenness of the ground and the vibration of the vehicle body as in the conventional example is avoided. Measurement with high accuracy is possible without being received, and when the value determined by the speed determination means is greater than or equal to the set value, the blocking means performs acceleration of the front wheel and braking of the rear wheel inside the turn. This speed discriminating means is linked with the engine crankshaft and sensors that are easy to arrange and maintain, such as potentiometers and limit switches that measure the operating position of the shift lever of the transmission. The rotational speed of the exposed rotating system, such as a rotating system and a cooling fan, can be configured using sensors that can be easily arranged and can be easily inspected and maintained like a proximity sensor.
[0008]
In addition, when the engine speed is less than the set value, the auxiliary blocking means prevents the speed increase of the front wheel and the braking of the rear wheel inside the turn, so the speed increase of the front wheel and the rear wheel inside the turn Even when an excessive load is applied when the braking is performed, an overload on the engine can be avoided. In particular, when driving on the road, the engine rotation speed is set to a relatively low value, but according to the present invention, it is determined that the engine rotation speed is in a non-working state, and unnecessary sudden turning on the road is also possible. It can be stopped.
[0009]
〔The invention's effect〕
Therefore, a work vehicle that can accurately measure the traveling speed of the vehicle body with high accuracy and reliably prevent the acceleration of the front wheel and the braking of the rear wheel inside the turn during high-speed traveling is reasonably constructed. is there. Furthermore, without only avoids engine stop due to an overload caused by the sharp turn, it was intended to allow for smooth motion distorting the body balance and avoid even sharp turn when traveling on the road.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, an engine 3 is disposed at the front of a vehicle body having a front wheel 1 and a rear wheel 2, and a main clutch in which power from the engine 3 is housed in a main clutch housing 4 is provided. The transmission case 5 is disposed at the rear part of the vehicle body, and is provided with a pair of left and right lift arms 7 that are driven up and down by a lift cylinder 6 at the rear end upper position of the transmission case 5, and a meter at the center part of the vehicle body A panel 8, a steering handle 9, and a driver seat 10 are disposed, and a position lever 11 for controlling the lift arm 7 is disposed on the right side of the driver seat 10. An agricultural tractor as an example of a work vehicle is configured by arranging a main transmission lever 12A and a sub-transmission lever 12B for shifting the transmission.
[0011]
A rotary tilling device 14 as a ground working device is detachably connected to the rear end position of the vehicle body via a two-point link mechanism 13, and between the two-point link mechanism 13 and the left and right lift arms 7. Further, the rotary tiller 14 can be moved up and down by the driving force of the lift cylinder 6 by interposing a pair of left and right lift rods 15. Further, a grounding type rear cover 14A is provided at the rear end position of the rotary tiller 14 so as to be swingable around the axis P in a lateral direction. The ground height of the rotary tiller 14 is determined from the swinging position of the rear cover 14A. A potentiometer type cover sensor 16 for measuring the thickness is provided.
[0012]
As shown in FIG. 2, a main clutch pedal 18 for disengaging the main clutch by a stepping operation is provided on the left side of step 17, and the right side of step 17 is independent of the left and right rear wheels 2 and 2. And a pair of left and right side brake pedals 19 for applying a braking force. Further, a steering operation system is formed which transmits the operating force of the steering handle 9 to the left and right front wheels 1 and 1 via a power steering mechanism (not shown).
[0013]
As shown in FIGS. 1, 3, and 4, a front wheel transmission device A is provided at a lower position of the transmission case 5, and the front wheel transmission device A has a peripheral speed of the front wheel 1 and a peripheral speed of the rear wheel 2. An equal speed drive state that equalizes, a speed increase drive state in which the peripheral speed of the front wheel 1 is increased from the peripheral speed of the rear wheel 2 in order to turn the vehicle body with a small radius, and a two-wheel drive that does not transmit power to the front wheel 1 It is configured to be able to reveal the state. That is, the front wheel transmission A is an intermediate shaft through which the power from the input shaft 21 for inputting the power from the transmission 5A of the transmission case 5 to the differential 2A of the rear wheel 2 is transmitted via the gear interlocking mechanism 22. 23, a front wheel drive shaft 24 supported in parallel with the intermediate shaft 22, a friction multi-plate standard clutch 26 for transmitting the power from the intermediate shaft 23 to the front wheel drive shaft 24 through a standard gear mechanism 25, A friction multi-plate type speed-up clutch 28 that transmits power from the shaft 23 to the front wheel drive shaft 24 through the speed-up gear mechanism 27 is provided. The standard clutch 26 and the speed-up clutch 28 are respectively engaged by supplying pressure oil. It is configured to reach the state and transmit power. Further, a transmission system is formed for transmitting the power from the front end of the front wheel drive shaft 24 to the differential device 1A of the front wheel 1 via the intermediate transmission shaft 29.
[0014]
In addition, friction side brakes 31 and 31 are provided as braking devices for applying a braking force to the axles 2B and 2B for the left and right rear wheels 2 and 2, and the side brake 31 is provided with an internal piston by supplying pressure oil. Is operated so that the friction plates are brought into pressure contact with each other, and a braking force proportional to the pressure oil pressure can be applied to the rear wheel 2.
Then, an electromagnetically operated switching valve 32 for controlling pressure oil for the standard clutch 26 and the speed increasing clutch 27, left and right electromagnetic proportional brake valves 33, 33 for the left and right side brakes 31, 31, and the lift cylinder 6 And a hydraulic pump 35 driven by the engine 3 to supply pressure oil to these valves 32, 33, 33, 34. Yes. The brake valves 33 and 33 are each of an electromagnetic proportional type that obtains an opening degree proportional to the current value supplied to the solenoid.
[0015]
As shown in FIG. 3, a potentiometer-type steering sensor 36 for measuring the steering operation amount of the steering operation system is provided, and a brake for detecting these stepping operations in the vicinity of the left and right side brake pedals 19, 19 is provided. A sensor 37, 37, a pickup type engine rotational speed sensor 38 for measuring the rotational speed of the engine 3 at a position close to the gear provided on the output shaft 3A of the engine 3, and determining the operating position of the main transmission lever 12A Thus, a potentiometer type main lever sensor 39A is provided at the base end portion, and a limit switch type sub lever sensor 39B is provided at the base end portion so as to determine the operation position of the sub transmission lever 12B.
[0016]
As shown in FIG. 5, the meter panel 8 includes a dial 41 for setting the driving mode of the front wheel 1, and the dial 41 maintains a state of driving only the rear wheel 2, and a “2WD” position. The “4WD” position where the constant speed drive state appears, and when the front wheel 1 is steered more than a set angle, the speed increasing power from the front wheel transmission A is transmitted to the front wheel 1 and the speed increasing drive. When the front wheel 1 is steered more than a set angle, the speed increasing power from the front wheel transmission device A is transmitted to the front wheel 1 and at the same time the rear wheel 2 inside the turn at the same time. The “double speed / AD” position for braking the side brake 31 can be set.
[0017]
As shown in FIG. 5, the tractor includes a control device 40 as a control means including a microprocessor. A mode switch 42 for determining a setting position of the dial 41 is provided to the control device 40. A steering sensor 36, the left and right brake sensors 37, 37, the rotational speed sensor 38, the main lever sensor 39A, the sub lever sensor 39B, and a potentiometer type lever for measuring the operation position of the position lever 11 From the sensor 43, a potentiometer type lift arm sensor 44 that measures the swing amount of the lift arm, a potentiometer type plow depth setting device 45 that sets a target plowing depth of the rotary tiller 14, and the cover sensor 16 Is formed, and a standard class of the switching valve 32 is formed. The operating solenoid 32L on the operation side including the switch 26, the speed increasing solenoid 32H on the operation side including the speed increasing clutch 28 of the switching valve 32, the brake solenoids 33S and 33S of the brake valves 33 and 33, and the lift valve 34 are raised. A system for outputting a signal to each of the ascending solenoid 34U that operates to the side and the descending solenoid 34D that operates the lift valve 34 to the descending side is formed.
[0018]
Further, a coupler 46 that can be separated from the input signal system from the cover sensor 16 to the control device 40 is interposed so that the signal system can be separated when the rotary tiller 14 is separated from the vehicle body. When the coupler 46 is separated by providing a pull-up resistor 47 on the signal line on the control device 40 side, the voltage of the signal line is raised to the power supply voltage to indicate that the coupler 46 is in the separated state from the voltage state. It is configured so that it can be determined.
[0019]
When the position lever 11 is operated, the setting position of the position lever 11 measured by the lever sensor 43 is set to the target height with respect to the vehicle body, and the dead zone is formed based on the target height. The position control mode is set so that the rotary tiller 14 is moved up and down until the signal value measured by the lift arm sensor 44 is reached. When the position lever 11 is set to the lowest position, the automatic tilling control is performed. In addition, in this automatic plowing depth control, a target plowing depth based on the ground is set by the plowing depth setting unit 45, and the cover sensor 16 is within the dead zone formed based on the target plowing depth. The form of control is set so that the rotary tiller 14 is moved up and down until the signal value measured at is reached.
[0020]
The control device 40 is set with a program for controlling the front wheel transmission A and the side brake 31 in addition to the lifting control of the rotary tiller 14 described above. That is, as shown in the flowchart of FIG. 6, when the signal from the mode switch 42 is input to determine the driving mode of the front wheel 1 and the switch 2 is operated to the “2WD” position, the switching valve 32 is operated to the neutral position. Then, the state where the transmission to the front wheel 1 is cut off is maintained (steps # 101 to # 103), and when the mode switch 42 is operated to the position of “4WD”, the standard solenoid 32L of the switching valve 32 is turned off. The four-wheel drive state is maintained by driving (steps # 104 and # 105). Otherwise, the standard solenoid 32L of the switching valve 32 is driven to set the four-wheel drive state, and the lift arm sensor When it is determined that the lift arm 7 is not at the upper limit based on the signal from 44, the signal from the cover sensor 16 exists within a predetermined voltage range, and the rotary tiller 14 is If it is determined that the connection is established (steps # 106 to # 110), the turning control routine is processed (step # 200). If these conditions are not satisfied, the standard solenoid 32L of the switching valve 32 is used. The four-wheel drive state is maintained by maintaining this drive state, and this control is continued until reset (step # 111).
[0021]
The reason why the turning control routine is inhibited when the lift arm 7 is at the upper limit is that the traveling with the ground working device such as the rotary tiller being raised to the upper limit is in a non-working state, so the small radius is required. The reason why the turning control routine is blocked when the signal input from the cover sensor 16 does not exist within the predetermined voltage range is that the signal voltage input to the control device 40 is substantially the same. This is because, when the power supply voltage is increased, the rotary tiller 14 is separated from the vehicle body and is in a non-working state, and turning at a small radius is not necessary during such non-working.
[0022]
As shown in the flowchart of FIG. 7, in the turning control routine (# 200 step), when the signal from the engine rotational speed sensor 38 is input and it is determined that the rotational speed of the engine 3 is less than the set value, switching is performed. The drive state of the standard solenoid 32L of the valve 32 is maintained to maintain the four-wheel drive state, the brake valve 33 is maintained in the neutral position, and the side brake 31 is maintained in the non-braking state (the brake sensor 37 Only when it is detected that the engine has been operated, the corresponding side brake 31 is braked) (steps # 201 to # 204), and even when it is determined that the rotational speed of the engine 3 is equal to or higher than the set value, Based on the signals from the main lever sensor 39A and the sub lever sensor 39B, the traveling speed of the vehicle body is determined from the gear position of the transmission 5A. Even when the traveling speed is equal to or higher than the set value, the driving state of the standard solenoid 32L of the switching valve 32 is maintained and the four-wheel driving state is maintained (steps # 205 to # 207) in the same manner as described above. Even when the speed is less than the set value, the drive state of the standard solenoid 32L of the switching valve 32 is maintained even when it is determined that the steering operation angle determined based on the signal from the steering sensor 36 is less than the set angle θ. Thus, the four-wheel drive state is maintained, the brake valve 33 is held in the neutral position, and the side brake 31 is maintained in the non-braking state (# 208, # 209 steps). The speed discriminating means is constituted by a program for discriminating the traveling speed of the vehicle body from the gear position of the transmission 5A and the rotational speed of the engine 3.
[0023]
Next, when it is determined that the steering operation angle determined based on the signal from the steering sensor 36 is equal to or larger than the set angle θ, the operation position of the mode switch 42 is determined and “double speed / AD” is determined. Only when it is in the position, the solenoid 33S of the brake valve 33 for the side brake 31 inside the turn is driven to brake the side brake 31 inside the turn, and the rotary tiller 14 is raised to the upper limit, and the switching valve 32 is increased. Control for increasing the speed of the front wheel 1 by driving the speed solenoid 32H and operating the speed increasing clutch 28 of the front wheel transmission device A until the front wheel 1 is restored to a value smaller than the set angle θ. (Steps # 210 to # 214). Note that when the rotation of the engine 3 is less than the set value , the auxiliary blocking means is configured by a program that blocks the acceleration of the front wheel 1 and the braking of the side brake 31, and the gear position of the transmission 5A and the rotation of the engine 3 are configured. Blocking means is configured by a program for blocking the acceleration of the front wheel 1 and the braking of the side brake 31 based on the traveling speed determined from the speed.
[0024]
The brake valve 33 is an electromagnetic proportional type that obtains an opening degree that is directly proportional to the value of the control current supplied to the solenoid 33S, and the braking force can be adjusted by the current supplied to the solenoid 33S. ing. And although not described in the flowchart, by increasing the current value supplied to the solenoid 33S as the traveling speed is higher, the piston of the brake 31 is quickly operated to start braking. The control operation of the control device 40 is also set so as to shorten the time and perform a turn at a desired position. The controller 40 is configured to send an intermittent signal to the solenoid 33S, and can adjust the current value supplied to the solenoid 33S in a PWM manner by setting the duty ratio of the intermittent signal. In order to control this current value with high accuracy, the pressure of the hydraulic fluid supplied from the hydraulic pump 35 is obtained based on the rotational speed of the engine 3 measured by the engine rotational speed sensor 38 and supplied to the solenoid 33s of the brake valve 33. The control operation of the control device 40 is set so as to correct the current value.
[0025]
Thus, in this tractor, when the operation is performed with the mode switch 42 set to either the “double speed” position or the “double speed / AD double speed” position, the front wheel 1 increases in conjunction with the steering operation. Speed or acceleration of the front wheel 1 and braking of the rear wheel 2 on the inside of the turn are automatically performed to enable turning with a small radius and, for example, the mode switch 42 is moved to the “double speed” position, or Even when traveling on the road with the rotary tiller 14 not raised to the upper limit in the state set to the “double speed / AD double speed” position, the necessity of turning at a small radius is determined based on the traveling speed and the front wheels 1. Increase the speed of 1 and prevent the braking operation of the rear wheel 2 inside the turn. This prevents turning of the car body by turning with a small radius when driving at high speed, and avoiding turning with an unnecessary small radius. Good operation feeling with no sense of incongruity In it has become a thing that enables a steering operation.
[0026]
Further, when the rotary tiller 14 is not connected to the vehicle body, the steering operation exceeding the set angle θ is performed even when the rotary tiller 14 is connected to the vehicle body and the vehicle is raised to the upper limit position. Even if this is done, the front wheel 1 is not increased in speed, so that the operator's sense of operation of the steering wheel is not distorted, and the vehicle can run with a stable posture of the vehicle body. In particular, when the rotary tiller 14 is in contact with the ground during operation, the rotary tiller 14 is operated in conjunction with the steering operation without specially performing an operation of raising the rotary tiller 14. Since the control to raise the upper limit is performed, the labor of the operator is saved, and an easy work is enabled.
[0027]
In particular, when the rotational speed of the engine 3 is low, the front wheel 1 is not accelerated and the side brake 31 is not braked, so that the engine 3 is prevented from being stopped due to overload, and the transmission 5 The speed of the vehicle body is discriminated on the basis of the shift speed of the engine 3 and the rotational speed of the engine 3, and when this speed is high, the front wheel 1 is not accelerated and the side brake 31 is not braked. The vehicle body balance is prevented from deteriorating due to turning in the traveling state, and stable traveling is enabled. In order to determine the traveling speed, the speed of the transmission 5 and the rotational speed of the engine 3 are determined. Since it is based on the above, it is possible to discriminate the traveling speed with high accuracy and perform reliable check prevention while having a simple structure.
[0028]
[Another embodiment]
In the present invention, in addition to the above embodiment, for example, a sensor can be arranged to measure the speed of a system that drives a cooling fan or a system that drives a camshaft of an engine to determine the rotational speed of the engine. It is also possible to use the alternator as a sensor so as to measure the rotational speed of the engine based on the voltage of the signal from the alternator and the period of the output signal. It is also possible to provide a potentiometer or the like for measuring the operation amount of the operation system formed between the transmission operating tool and the transmission to determine the gear position.
[Brief description of the drawings]
[Fig. 1] Overall side view of tractor [Fig. 2] Plan view of front of tractor [Fig. 3] Plan view of transmission system of vehicle body [Fig. 4] Hydraulic circuit diagram of vehicle body [Fig. 5] Block circuit diagram of control system [Fig. FIG. 6 is a flowchart of the main control operation. FIG. 7 is a flowchart of a turning control routine.
DESCRIPTION OF SYMBOLS 1 Front wheel 2 Rear wheel 5A Transmission 31 Brake device 38 Rotational speed sensor 40 Control means

Claims (2)

Drive type left and right front wheels configured to be steerable, drive type left and right rear wheels, and a braking device for independently braking the left and right rear wheels, and a rotary tiller at the rear of the vehicle body Connected,
In conjunction with the steering operation of the front wheel, the peripheral speed of the front wheel is increased from the peripheral speed of the rear wheel, the braking device on the inner side of the turn is braked, and the rotary tillage device is raised. A work vehicle equipped with a control means,
A speed determining means for determining a traveling speed of the vehicle body from a speed change position of a transmission device provided in the vehicle body and an actual rotational speed of the engine measured by the rotation speed sensor ; Prepared,
When the traveling speed discriminated by the speed discriminating means is equal to or higher than the set value, the front wheel speed increasing state, the braking device braking state, and the rotary tiller are prevented from being restrained. A blocking means to
When the actual rotational speed of the engine determined by the rotational speed sensor is less than a set value, the speed increase state of the front wheels, the braking state of the braking device, and the rotary tillage device rise A work vehicle equipped with sub-blocking means to block the movement. As a result of detection when the traveling speed is greater than or equal to the set value or when the engine speed is less than the set value, the acceleration state of the front wheels, the occurrence of the braking state of the braking device, and the rotary tillage A mode to prevent the device from rising, and
And when the running speed is equal to or more than the set value, regardless of the detection when the engine rotational speed is less than the set value, claims and mode that does not perform the check blocking, Ru Oh provided switching operation possible mode switch The work vehicle according to 1.

Images