JPH0571406B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a two-wheel drive system in a vehicle drive system.
The present invention relates to a four-wheel drive automatic switching device, and particularly to a two-wheel drive/four-wheel drive automatic switching device that can perform accurate automatic switching control.

[Conventional technology]

Generally, when comparing two-wheel drive and four-wheel drive, four-wheel drive uses four wheels to grip the road surface, so the limit of driving force transmission is higher than two-wheel drive. In other words, when the engine driving force is large, such as when starting in a low gear and with a large accelerator opening, with two-wheel drive, the engine driving force cannot be completely transmitted to the road surface. ,
In extreme cases, slipping may occur, but with four-wheel drive, such phenomena are less likely to occur, and the engine's driving force can be used more effectively.

[Problem that the invention seeks to solve]

Therefore, in a vehicle drive system that has a coupling mechanism that can switch between two-wheel drive and four-wheel drive, switching between two-wheel drive and four-wheel drive is performed in consideration of the driving force limit and engine driving force. However, in the past, this switching was done manually, so the engine driving force was not used effectively.

In addition, recently, the engine accelerator opening, wiper operation/non-operation, and brake operation/non-operation are detected, and the combination of these detection signals automatically switches between two-wheel drive and four-wheel drive. However, such detection signals do not necessarily represent the torque state of the vehicle, and accurate control remains undesirable.

The present invention solves the above-mentioned problems, and in particular, it is possible to accurately control automatic switching between two-wheel drive and four-wheel drive by picking up parameters representing the actual output state of the engine. /4
The object of the present invention is to provide an automatic wheel drive switching device.

[Means for solving problems]

In order to achieve the above object, the present invention provides an automatic two-wheel drive/four-wheel drive switching device equipped with a switching mechanism that automatically switches between two-wheel drive and four-wheel drive. an opening detection section, a gear detection section that detects the gear of the transmission, a rotation speed detection section that detects the rotation speed of the drive device, and a rotation speed detection section that detects the rotation speed of the drive device. A torque map memory unit that stores a torque map for the vehicle, and an engine that is at the limit that can grip the vehicle so that the vehicle's tires do not slip against the road surface because the driving force of the vehicle's engine exceeds the frictional force of the road surface. a driving force transmission limit setting unit that sets a driving force transmission limit value that is the driving force of a driving force calculation unit that calculates the actual driving force; and a driving force calculation unit that calculates the actual driving force, and compares the actual driving force calculated by the driving force calculation unit with a driving force transmission limit value of the driving force transmission limit setting unit to determine the actual driving force. A configuration in which a signal is output to the switching mechanism to switch to four-wheel drive when the force is larger than the driving force transmission limit value, and to switch to two-wheel drive when the actual driving force is smaller than the driving force transmission limit value. has.

[Action and effect of invention]

The two-wheel drive/four-wheel drive automatic switching device of the present invention compares the driving force with the driving force transmission limit, and when the driving force is greater, outputs a four-wheel drive signal, and when it is smaller, outputs a two-wheel drive signal. Since the output is output to the switching mechanism, switching control between 2-wheel drive and 4-wheel drive can be performed accurately.
Engine driving force can be transmitted effectively.

〔Example〕

Examples will be described below with reference to the drawings.

Fig. 1 is a diagram showing the configuration of one embodiment of the automatic two-wheel drive/four-wheel drive switching device of the present invention, Fig. 2A is a torque map of a vehicle with a manual transmission, and Fig. 2B is a diagram of an automatic transmission. FIG. 3 is a diagram showing an example of a driver selection button in the driving force transmission limit setting means.

In FIG. 1, 1 is an accelerator opening detection section, 2
Reference numeral 3 indicates a gear stage detection section, 3 indicates a rotation speed detection section, 4 indicates a driving force calculation section, 5 indicates a torque map storage section, 6 indicates a driving force transmission limit setting section, and 7 indicates a comparison determination section.

The torque map storage section 5 stores a torque map of the drive device in advance. As shown in FIG. 2A or B, the torque map of the drive device can be drawn by considering the accelerator opening, the number of gear stages (1st gear, 2nd gear, etc.), and the drive device rotational speed as variables. In Figure 2, the accelerator opening is 100%.
(at full throttle), but since the torque level also changes as the accelerator opening changes, a torque map corresponding to each accelerator opening will be obtained.

In addition, the driving force of the vehicle's engine exceeds the frictional force of the road surface during 2-wheel drive or 4-wheel drive, so the vehicle's tires are at the limit at which they can grip without slipping with the road surface. The driving force transmission limit value setting unit 6, which stores the driving force transmission limit value which is the driving force of the engine of As shown in FIG. 3, for example, since the condition of the road surface (frictional force of the road surface) varies depending on the weather, the driver may be able to select the driving force transmission limit value using a button depending on the condition of the road surface.

When the torque map and the driving force limit value as described above are set and stored, during actual driving, the driving force calculation unit 4 calculates the accelerator opening, the number of gears, and the driving speed (engine speed, transmission speed, etc.) at each point in time. (input or output rotation speed) and compares these detected values with the torque map to calculate the driving force at that point in time. Then, the calculated driving force value is sent to the comparison and determination section 7.

On the other hand, the comparison/judgment unit 7 compares the driving force value and the driving force transmission limit value, and if the driving force value is smaller, 2 is determined.
A wheel drive signal is output, and if it is larger, a four-wheel drive signal is output. The switching mechanism is controlled by this output signal. Therefore, depending on whether the switching mechanism is activated or not,
When switching between wheel drive and four-wheel drive, the two-wheel drive signal and the four-wheel drive signal are inverted signals, that is, one signal indicating whether or not it is two-wheel drive or whether it is four-wheel drive. good.

Note that the rotation speed detection unit 3 uses a torque map for the engine rotation speed when detecting the engine rotation speed, and a torque map for the engine rotation speed when detecting the input rotation speed or the output rotation speed of the transmission. It is sufficient to store a torque map for the number or output rotation speed. Therefore, in the above example, the engine rotation speed is used as the rotation speed of the drive device, but even if the input rotation speed or output rotation speed of the transmission is used instead, it will still have its own unique torque map. If this is done, by detecting the accelerator opening, the number of gears, and the number of rotations of the drive device during driving, the driving force of the vehicle at that point in time can be accurately detected from comparison with the torque map. And as already mentioned, the driving force value,
The driving force limit value for two-wheel drive is compared, and if the driving force value exceeds the limit value, four-wheel drive may be selected.

As is clear from the above description, the present invention
Various modifications are possible and the invention is not limited to the above embodiments. According to the present invention, since the torque state of the vehicle is accurately detected and the switching between two-wheel drive and four-wheel drive is automatically performed, the engine driving force is effectively transmitted, resulting in an excellent economical effect. Not only is it possible to maintain good driving sensation and driving stability.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of one embodiment of the automatic two-wheel drive/four-wheel drive switching device of the present invention, Fig. 2A is a torque map of a vehicle with a manual transmission, and Fig. 2B is a diagram of an automatic transmission. FIG. 3 is a diagram showing an example of a driver selection button in the driving force limit setting means. 1... Accelerator opening detection section, 2... Gear stage detection section, 3... Rotation speed detection section, 4... Driving force calculation section,
5...Torque map storage unit, 6...Driving force transmission limit setting unit, 7...Comparison determination unit.

Claims (1)

[Scope of Claims] 1. In a two-wheel drive/four-wheel drive automatic switching device equipped with a switching mechanism for switching between two-wheel drive/four-wheel drive, an accelerator opening detection section that detects an accelerator opening of an engine; A gear stage detection section that detects the gear stage of the transmission, a rotation speed detection section that detects the rotation speed of the drive device, and a map of the driving force set by the accelerator opening, gear speed, and rotation speed of the drive device. A torque map memory unit that stores the torque map, and the maximum engine driving force that allows the vehicle to grip without causing the vehicle's tires to slip against the road surface because the vehicle engine's driving force exceeds the frictional force of the road surface. a driving force transmission limit setting section that sets a driving force transmission limit value, and reads signals detected from the accelerator opening degree detection section, gear position detection section, and rotation speed detection section into the torque map storage section to perform actual driving. a driving force calculation unit that calculates the force; and a driving force calculation unit that calculates the actual driving force by comparing the actual driving force calculated by the driving force calculation unit with a driving force transmission limit value of the driving force transmission limit setting unit. A signal is output to the switching mechanism to switch to four-wheel drive when the actual driving force is larger than the driving force transmission limit value, and to two-wheel drive when the actual driving force is smaller than the driving force transmission limit value. Two-wheel drive/
4-wheel drive automatic switching device. 2. The two-wheel drive/four-wheel drive automatic switching device according to claim 1, wherein the rotation speed of the drive device is the engine rotation speed. 3. The two-wheel drive/four-wheel drive automatic switching device according to claim 1, wherein the rotation speed of the drive device is a transmission input rotation speed. 4. The two-wheel drive/four-wheel drive automatic switching device according to claim 1, wherein the rotation speed of the drive device is the transmission output rotation speed. 5. The two-wheel drive/four-wheel drive system according to claim 2, wherein the driving force transmission limit setting section is a storage means for storing a predetermined driving force transmission limit value. Automatic drive switching device. 6. The two-wheel drive/four-wheel drive according to claims 2 to 4, wherein the driving force transmission limit setting section allows the driver to support the driving force transmission limit value with a switch. Automatic switching device.