JP3952065B2 - Tractor front wheel drive controller - Google Patents

Description

  The present invention relates to a front wheel drive control device for a tractor.

  A four-wheel drive vehicle such as a tractor drives the front two wheels and the rear two wheels so as to have substantially the same peripheral speed when going straight. If the vehicle is turned in this state, the turning performance is poor. Therefore, when the vehicle is turning, the front wheels are stopped and only the rear wheels are driven to improve the turning performance. There is known a front-wheel-increasing four-wheel drive system at the time of turning which is driven at a higher speed than the rear wheel to reduce the turning speed.

The front-wheel-accelerated four-wheel drive system at the time of turning detects the steering angle of the wheel, senses turning of the vehicle, automatically operates the speed increasing mechanism provided in the front-wheel drive system, and the peripheral speed of the front wheels Turn the car at a speed approximately twice that of the rear wheel. In addition, when the vehicle is turned at high speed while traveling on a general road or the like, if the speed increasing mechanism operates, the vehicle suddenly turns and is dangerous, so when the transmission is shifted to a high speed position, Means is provided for restricting the speed increasing mechanism so as not to operate.
Utility Model 1-96341 JP-A-4-317823

  As described above, the conventional front-wheel-acceleration four-wheel drive system during turning is provided with a restricting means that prevents the speed-increasing mechanism from operating when turning at a high speed. However, since the restricting means works when the transmission is at a high speed position, for example, when the operation is performed such that the transmission is adjusted during turning, the restricting means is activated or released and the turning performance is not good. There is a drawback.

  Further, even if the operation of the speed increasing mechanism is restricted by detecting the vehicle speed, the speed increasing mechanism is intermittently operated when the vehicle speed fluctuates during turning of the vehicle, so that the driving is not smoothly performed. Therefore, in a tractor equipped with a speed increasing mechanism, a technical problem to be solved in order to smoothly regulate the operation of the speed increasing mechanism is generated, and the present invention solves this problem. Objective.

The present invention has been proposed in order to achieve the above object, and a front wheel drive control device for a tractor having a speed increasing mechanism for driving a front wheel at a higher speed than a rear wheel when the vehicle turns from a slow turn to a sudden turn. The vehicle is provided with a front wheel rotation sensor for the front wheels and a rear wheel rotation sensor for the rear wheels , the vehicle speed is detected by reading the front shaft rotation sensor and the rear shaft rotation sensor, and the front and rear wheels are in a synchronized state. It is configured to detect the slip state of the rear wheel, and the speed increasing mechanism can be operated when the vehicle speed is less than a certain vehicle speed or the vehicle speed cannot be detected, and the speed increasing mechanism is operated at a certain vehicle speed or higher. In addition, during the speed restriction of the front wheels by the speed increasing mechanism unit , even if the vehicle speed drops below the constant vehicle speed during a sudden turn of the vehicle , the operation control of the speed increasing mechanism unit is continued . Steering to detect the steering angle of the front wheels When the steering angle of the front wheels is below a predetermined value by the sensor, it is determined that the vehicle is traveling straight or running slowly, and the synchronization state of the front and rear wheels is determined. When the front and rear wheels are synchronized The rear wheel only has two-wheel drive, and when the front and rear wheels are not synchronized, the rear wheel slip state is discriminated. When the rear wheel slips, it is four-wheel drive and the rear wheel slips. When the vehicle is in a straight-turned state or a gentle turning state, it is determined to be a four-wheel drive if the vehicle is in a straight-ahead state, and to a two-wheel drive with only the rear wheel if the vehicle is in a gentle-turning state. A monitor is provided, and when the front and rear wheel lights of the monitor are displayed to indicate the front and rear wheel drive status, when the vehicle is in a two-wheel drive state with only the rear wheels, the front wheel lamp is turned off and the rear wheel lamp is lit. When in a four-wheel drive state, Both wheel lamps are lit, the front wheel lamp blinks when the rear wheel is braked during four-wheel drive, and the front wheel lamp lights in a different color from the four-wheel drive when in the front wheel acceleration state The present invention provides a tractor front wheel drive control device that is configured as described above .
(Operation of the invention)
In the tractor configured as described above , the vehicle speed of the vehicle, the synchronized state of the front and rear wheels, and the slip state of the rear wheels are detected by the front axle rotation sensor of the front wheels and the rear axle rotation sensor of the rear wheels. When the vehicle speed is less than a certain vehicle speed or when the vehicle speed cannot be detected, the speed increasing mechanism can be operated. Above a certain vehicle speed, the operation of the speed increasing mechanism is restricted, and the speed increasing mechanism During the speed restriction of the front wheels by the part , the operation restriction of the speed increasing mechanism is continued even when the vehicle speed drops below the constant vehicle speed during a sudden turn of the vehicle .
When the steering angle of the front wheels is equal to or less than a predetermined value, it is determined that the vehicle is traveling straight or traveling slowly, and the synchronization state of the front and rear wheels is determined. When the front wheel and the rear wheel are synchronized, only the rear wheel is driven. When the front wheel and the rear wheel are not synchronized, the slip state of the rear wheel is determined. When the rear wheel slips, four-wheel drive is performed, and when the rear wheel does not slip, it is determined whether the vehicle is moving straight or slowly. When the vehicle is in a straight traveling state, four-wheel drive is used, and when the vehicle is in a gentle turning state, two-wheel drive is performed with only the rear wheels.
In addition, the driving states of the front and rear wheels are displayed on the vehicle monitor. When the vehicle is in a two-wheel drive state with only the rear wheels, the front wheel lamp is turned off and the rear wheel lamp is lit. When in a four-wheel drive state, both the front wheel lamp and the rear wheel lamp are lit. When the rear wheel is braked during four-wheel drive, the front wheel lamp blinks. When the front wheel is accelerated, the front wheel lamp lights in a different color from that used during four-wheel drive.

Since the present invention is configured as described above, it is possible to improve the safety of the tractor while improving the turning performance of the tractor by appropriately operating the speed increase restriction of the front wheels by the speed increasing mechanism .
In addition, it is configured to automatically switch between two-wheel drive and four-wheel drive with only the rear wheel depending on the driving state of the front and rear wheels, the turning state of the vehicle, and the slipping state of the rear wheel. Stable running and turning are possible without any problems.
In addition, the two-wheel drive, the four-wheel drive, and the front wheel acceleration state with only the rear wheels are displayed with the lighting and flashing of the lamp and the difference in the color of the lamp, so that the driving state of the vehicle is quickly This makes it possible to determine the next operation of the driver.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram of a transmission system and a control system of a four-wheel drive vehicle such as a tractor. Engine power is transmitted to a rear wheel via a main clutch and a transmission. Further, the power is branched during transmission to the rear wheel, and the power is transmitted to the front wheel via the speed increasing mechanism. Although illustration is omitted, the speed increasing mechanism section is provided with a direct coupling clutch and a speed increasing clutch, and one of the clutches is turned on by a command from the control section. For example, if the direct coupling clutch is on, the driving force of the rear wheels is transmitted to the front wheels as it is to achieve normal four-wheel driving, and if the speed increasing clutch is on, the driving force of the rear wheels is approximately doubled by the transmission gear. The four-wheel drive with the front wheel speed increased from the rear wheel. Further, if both clutches are off, the vehicle is in a neutral state, and the driving force of the rear wheels is not transmitted to the front wheels, and only the rear wheels are driven.

  Thus, a front shaft rotation sensor and a rear shaft rotation sensor are provided close to the speed change gear in the speed increasing mechanism, and the number of rotations of each rotation unit is read and input to the control unit. A vehicle speed detection sensor is provided to read the actual speed or theoretical speed of the vehicle (hereinafter referred to as “vehicle speed”), and a steering angle sensor is provided to read the steering angle of the front wheels. The vehicle speed may be calculated from the detected values by reading the rotation of the front shaft and the rear shaft. In addition, a mode selector switch is provided in the vicinity of the driver's operation panel so that the mode selector switch can be used to select a normal four-wheel drive mode or a work mode with a front wheel acceleration function. Which mode is the current mode.

  Next, the front wheel drive control method of the present invention will be described with reference to the flowchart of FIG. First, the steering angle of the front wheels is read by the steering angle sensor, and it is determined whether or not it is equal to or greater than a predetermined steering angle α (step 101). When the four-wheel drive vehicle is traveling straight ahead or traveling slowly, the steering angle of the front wheels is smaller than α, so if an acceleration restriction flag described later is on, it is cleared (step 102). The process proceeds to front wheel speed increase restriction control 103 to 107.

  Here, in step 103, it is determined whether or not the front and rear wheels are synchronized. When the front wheels and the rear wheels have different peripheral speeds, the slip state of the rear wheels is confirmed (step 104). When the rear wheel slips, 4WD is set to drive the four wheels (step 107). When the rear wheel does not slip, it is determined whether or not the vehicle is in a straight traveling state (step 105). If the vehicle is running straight, set 4WD as described above (step 105 → 107), and if the vehicle is turning slowly, set 2WD (step 106) to set only the rear wheels to two-wheel drive (step 106). Improve turning performance. When the front and rear wheels are in synchronization at step 103, the routine jumps to step 106, where the 2WD setting is made only for the rear wheels. After setting 2WD or 4WD, the process proceeds to step 108, and to continue control, the process returns to step 101.

  On the other hand, when the four-wheel drive vehicle makes a sudden turn at the steering angle α or more at step 101, the routine proceeds to step 109, where it is determined whether or not the speed increase restriction flag is on. When the speed increase restriction flag is off, the routine proceeds to step 110, where the vehicle speed is read by the vehicle speed sensor, and it is determined whether or not the vehicle speed is equal to or higher than the predetermined speed V. When the vehicle speed falls below the predetermined speed V, the front wheel speed increase setting is set so that the speed increasing mechanism described above is activated (step 112), and the peripheral speed of the front wheel when making a sharp turn is about twice that of the rear wheel. Increase the speed to a certain extent to reduce the turning speed of the vehicle.

  On the other hand, when the vehicle speed read in step 110 is equal to or higher than the predetermined speed V, the speed increase restriction flag is turned on (step 111), and the process proceeds to the forward speed increase restriction control in steps 103 to 107 described above. Even when the speed increase restriction flag is on in step 109, the routine jumps to step 103 to execute forward speed increase restriction control.

  That is, when the front wheel steering angle is greater than or equal to α and the vehicle speed is greater than or equal to the predetermined speed V and the speed increase restriction control is executed, the speed increase restriction flag is on, so the vehicle speed is equal to the predetermined speed. Even when the voltage drops below V, the speed increase restriction control is continued until the end of turning of the vehicle. Therefore, even if the vehicle speed fluctuates while the vehicle is turning sharply, the speed increasing mechanism portion does not operate intermittently, and the vehicle turns very smoothly.

  FIG. 3 shows a driver's seat operation panel 11 to which various instruments are attached. A mode changeover switch 12 is provided in the vicinity of the operation panel 11, and a monitor 13 for displaying the driving state of the front and rear wheels is provided. FIG. 4 is an enlarged view of the mode changeover switch 12 and allows the travel mode of the four-wheel drive vehicle to be switched as follows. A normal driving mode is provided at the center position of the switch position, a work mode having a front wheel speed increasing function is provided at the right side of the driving mode, and a four-wheel drive mode is always locked at the left side of the driving mode in a four-wheel drive state. Is provided. Since the most frequently used travel mode is arranged at the center of the switch position, the operability of the switch is improved, and an operation error of the switch can be prevented to ensure safety.

  FIG. 5 is an enlarged view of the monitor 13, and the driving state of the front and rear wheels is displayed by turning on the front wheel lamp 14 and the rear wheel lamp 15. FIG. When the vehicle is in a two-wheel drive state with only the rear wheels, the front wheel lamp 14 is turned off and the rear wheel lamp 15 is lit. In the four-wheel drive state, both the front wheel lamp 14 and the rear wheel lamp 15 are lit. When a brake is applied to the rear wheel during four-wheel drive, the braking force of the rear wheel acts on the front wheel that is not equipped with a brake. At this time, the front wheel lamp 14 blinks. Further, in the front wheel acceleration state, the front wheel lamp 14 is lit in a different color (for example, red) different from the four-wheel drive mode.

  Thus, the traveling state of the vehicle can be recognized by the operator in real time, and the operator can perform an appropriate driving operation. Here, the peripheral speed of the front wheel and the rear wheel is measured by the front shaft rotation sensor and the rear shaft rotation sensor described above, and based on the peripheral speed ratio of the front and rear wheels, two-wheel drive, four-wheel drive, and front wheel acceleration of only the rear wheel are measured. When drive control is performed so as to automatically set any of the four-wheel drive, when the vehicle is in an extremely low speed range, the rotation speed of the front and rear axes cannot be measured by the rotation sensor, and the front wheel drive control becomes uncontrollable. For this reason, in the ultra-low speed range where the peripheral speeds of the front and rear wheels cannot be detected, the four-wheel drive state is locked in consideration of safety. However, for example, in a narrow place such as a warehouse, when the turning operation is performed in an ultra-low speed region, there is a problem that the turning performance is deteriorated in a normal four-wheel drive state.

  6 and 7 are flowcharts of front wheel drive control taking into account the case where the peripheral speeds of the front and rear wheels cannot be detected. When the front wheel acceleration mode is manually set by a changeover switch, the front wheel increase shown in FIG. When speed control is performed and the changeover switch is set to a mode other than the front wheel acceleration mode, front wheel drive control shown in FIG. 7 is performed. First, the front wheel acceleration control routine will be described with reference to FIG. First, the steering angle of the front wheels is read by the steering angle sensor, and it is determined whether or not it is equal to or greater than a predetermined steering angle α (step 201). When the steering angle of the front wheels is smaller than α, the routine proceeds to step 202, where it is determined whether or not the vehicle speed can be detected. When the vehicle speed can be detected, the same control as the front wheel speed increase restriction control in steps 103 to 107 described in FIG. 2 is performed in steps 203 to 207, and 2WD setting (step 206) or 4WD setting (step 207). )I do. Further, when the vehicle speed is in the ultra-low speed range, the vehicle speed cannot be detected as described above, so 4WD is set in consideration of safety (step 202 → 207).

  On the other hand, when the steering angle of the front wheels becomes greater than or equal to α in step 201 and the vehicle turns sharply, the routine jumps to step 208, and the front wheel acceleration is set so that the speed increasing mechanism is activated. In such a case, the turning speed of the vehicle can be shortened by increasing the peripheral speed of the front wheels to about twice that of the rear wheels. Then, after setting the drive method in steps 206 to 208, the process proceeds to step 209, and to continue the control, the process returns to step 201.

  On the other hand, when the changeover switch is set to a mode other than the front wheel acceleration mode, the front wheel drive control shown in FIG. 7 is performed. In the figure, it is first determined whether or not the vehicle speed can be detected (step 301). When the vehicle speed can be detected, the control of steps 302 to 306 is performed in the same manner as the control of steps 203 to 207 in the above-described front wheel acceleration control routine, and 2WD setting (step 305) or 4WD setting (step 306).

  On the other hand, when it becomes impossible to detect the vehicle speed because the vehicle is in the ultra-low speed region, the routine proceeds from step 301 to step 307, where the steering angle of the front wheels is read to determine whether it is equal to or greater than a predetermined steering angle α. When the steering angle of the front wheels is smaller than α, the vehicle is in a straight or slow turning state, and so high turning performance is not required, so the routine proceeds to step 306 and 4WD is set. When the steering angle of the front wheels becomes greater than or equal to α in step 307, the routine jumps to step 308 to set the front wheel acceleration. That is, even when the vehicle is in an ultra-low speed range and vehicle speed detection is impossible, when performing a turn-back operation or the like, the front wheel speed-up operation is performed, and the turning performance of the vehicle is improved.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

The block diagram of the transmission system and control system of a tractor which is one Example of this invention. The flowchart which shows an example of the front-wheel drive control method. The front view of the operation panel of a driver's seat. The enlarged view of a mode switch. The enlarged view of a monitor. The other example of the front-wheel drive control method is shown, and the flowchart of a front-wheel acceleration control routine. The other example of the front-wheel drive control method is shown, and the flowchart of a front-wheel drive control routine.

Explanation of symbols

α: Steering angle,
13 ... monitor, 14 ... front wheel lamp, 15 ... rear wheel lamp.

Claims (1)

In a front wheel drive control device for a tractor having a speed increasing mechanism for driving a front wheel at a speed higher than that of a rear wheel when the vehicle turns from a slow turn to a sudden turn, the vehicle includes a front wheel rotation sensor and a rear wheel. A rear-axis rotation sensor is provided, and the vehicle speed is detected by reading the front-axis rotation sensor and the rear-axis rotation sensor, and the synchronized state of the front and rear wheels and the slip state of the rear wheels are detected, and the vehicle speed of the vehicle is constant. The speed increasing mechanism can be operated when the vehicle speed is less than the vehicle speed or when the vehicle speed cannot be detected, while the speed increasing mechanism is restricted from operating at a certain vehicle speed or more, and the speed increase of the front wheels is being controlled by the speed increasing mechanism. , even if the vehicle speed during sudden turning of the vehicle becomes lower than the predetermined vehicle speed, a structure to continue working inhibition of the speed increasing mechanism, front wheel steering angle by the steering angle sensor for detecting a steering angle of said front wheel If the vehicle is below the specified value, the vehicle Judged that the vehicle is moving forward or slowly turning and determining the synchronized state of the front and rear wheels.When the front and rear wheels are synchronized, only the rear wheels are driven, and the front and rear wheels are synchronized. When there is no slip, it is configured to determine the slip state of the rear wheel, when the rear wheel is slipping, it is four-wheel drive, and when there is no slip on the rear wheel, it is determined whether the vehicle is going straight or gently turning However, if the vehicle is in a straight traveling state, it is set to four-wheel drive, and if the vehicle is in a slow turning state, it is set to two-wheel drive with only the rear wheels. Further, a monitor is provided on the vehicle, and the front wheel lamp and the rear wheel lamp on When displaying the front and rear wheel drive status, when the vehicle is in a two-wheel drive mode with only the rear wheels, the front wheel lamp is extinguished and the rear wheel lamp is lit. Lights up and the brakes are applied to the rear wheels during four-wheel drive. Front lamp when digits are a blinking state, the front-wheel drive control device of a tractor, characterized by being configured to light in a different other color than the time of front wheel lamps four-wheel drive when the front wheel acceleration state.

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