JPH039472Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an improvement in switching control in a four-wheel drive vehicle capable of switching between two-wheel drive and four-wheel drive.

Conventional Technology There have been four-wheel drive vehicles in the past, but they were designed to switch from four-wheel drive to two-wheel drive by manual operation based on the driver's judgment.

Problems that the invention aims to solve Furthermore, because conventional four-wheel drive vehicles had to manually switch between four-wheel drive and two-wheel drive based on the driver's judgment, the operation was cumbersome. Ta. Therefore, the four-wheel drive vehicle of the present invention is capable of automatically switching to four-wheel drive when starting and at low acceleration to prevent slipping even on low-friction roads. The purpose of this is to prevent switching between wheel drive and two-wheel drive from being performed more frequently than necessary.

Means for Solving the Problems This invention was devised in view of the above objectives.
In a four-wheel drive vehicle in which switching between four-wheel drive and two-wheel drive while driving is controlled by vehicle speed, when increasing speed, the vehicle speed exceeds a first boundary vehicle speed that is relatively low and a second boundary vehicle speed that is faster than the first boundary vehicle speed. The vehicle has a means for switching the drive system from four-wheel drive to two-wheel drive when the vehicle speed exceeds the threshold vehicle speed, and switching the drive system from two-wheel drive to four-wheel drive when the vehicle speed falls below the first threshold vehicle speed during deceleration. This is a characteristic feature.

Function When accelerating, the drive system is switched from four-wheel drive to two-wheel drive when the vehicle speed exceeds the first boundary vehicle speed and reaches a second boundary vehicle speed, which is relatively faster than the first boundary vehicle speed, and when decelerating, the vehicle speed changes. The drive system is switched from two-wheel drive to four-wheel drive when the vehicle speed falls below the first boundary speed.

Embodiment To explain the above using illustrations, as shown in FIG. 1, the vehicle speed is detected as a pulse signal by the vehicle speed sensor 1, and is calculated by the calculation means 2. This calculation result is input to the vehicle speed determining means 3, which determines the low vehicle speed position where four-wheel drive is always applied from the start, that is, the first boundary vehicle speed (for example, 30 km/h).
and a second boundary vehicle speed that is slightly higher than that (for example, 40
km/h). Then, the vehicle speed section to which the input vehicle speed signal belongs is determined, and the determined vehicle speed section is output to the output determining means 4. Upon receiving this signal, the output determining means 4 always selects four-wheel drive when the vehicle speed is below the first boundary speed.
From the boundary vehicle speed to the above-mentioned second boundary vehicle speed, it is determined that four-wheel drive is used during acceleration and two-wheel drive is used during deceleration, and the solenoid 5 of the 4WD switching means is output.
It transmits and excite it. Additionally, when the second boundary vehicle speed is exceeded, the timer 6 counts a certain period of time, and if it is within the certain period of time, a command is sent to the solenoid to switch to four-wheel drive when accelerating and to two-wheel drive when decelerating. . Note that here, the calculation means 2, the vehicle speed determination means 3, the output determination means 4, and the timer 6 are integrated into the controller C.

A four-wheel drive vehicle equipped with the controller C described above is equipped with a controller C as shown in FIGS. 2 and 3.
The solenoid 5 is energized and the actuator 7 is operated, and the actuation of the actuator operates the four-wheel drive switching clutch 8. When the clutch is engaged, the drive torque from the engine 9 is transferred via the propeller shaft 10. The driving torque is transmitted to the rear wheels 11 to provide four-wheel drive, and when the clutch is not engaged, the driving torque is not transmitted to the propeller shaft 10, resulting in two-wheel drive.

Note that 12 is a front differential, and 13 is a rear differential.

The above will be explained based on the flowchart shown in FIG. 4. If the detected vehicle speed is below the first boundary vehicle speed (for example, 30 km/h), the 4WD flag is set and the vehicle becomes 4-wheel drive. Further, the vehicle speed is equal to or higher than the first boundary vehicle speed and the second boundary vehicle speed (for example, 40
Km/h), the vehicle is switched to four-wheel drive during an acceleration state where the vehicle speed increases, and to two-wheel drive during a deceleration state. Furthermore, the vehicle speed is the second
If the vehicle speed is above the boundary speed, the 4WD flag is reset and the vehicle becomes two-wheel drive.

Effects of the invention As is clear from the above, according to the invention, changes in cornering characteristics caused by switching between four-wheel drive and two-wheel drive when turning can be minimized, so that the vehicle does not disturb the trajectory expected by the driver. In addition to being able to make stable turns without
This has the effect of minimizing changes in vehicle behavior caused by switching between four-wheel drive and two-wheel drive even when driving straight. Furthermore, since the switching operation is performed automatically, the driver's annoyance is eliminated.

[Brief explanation of drawings]

Fig. 1 is a block diagram that realizes the function of the controller that controls four-wheel drive from start to low vehicle speed according to the present invention, and Fig. 2 is an overall layout diagram of a four-wheel drive vehicle controlled by the controller. FIG. 3 is a diagram related to the hardware of the controller, and FIG. 4 is a flowchart showing the software of the controller. DESCRIPTION OF SYMBOLS 1... Vehicle speed sensor, 2... Calculating means, 3... Vehicle speed determining means, 4... Output determining means, 5... Solenoid, 6... Timer, 7... Actuator, 8
...4WD switching clutch, 10...propeller shaft.

Claims (1)

[Scope of utility model registration request] In a four-wheel drive vehicle in which switching between four-wheel drive and two-wheel drive while driving is controlled by vehicle speed, when increasing speed, the vehicle speed exceeds a relatively low first boundary vehicle speed.
When the vehicle speed reaches a second boundary vehicle speed higher than the boundary vehicle speed, the drive system is switched from four-wheel drive to two-wheel drive, and during deceleration, when the vehicle speed falls below the first boundary vehicle speed, the drive system is changed from two-wheel drive to four-wheel drive. A four-wheel drive vehicle characterized by having a means for switching.