JPH0571405B2 - - 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 more particularly to a two-wheel drive/four-wheel drive automatic switching device in a drive system equipped with an automatic transmission having a torque converter.

[Prior Art] Generally, when comparing two-wheel drive and four-wheel drive,
Four-wheel drive uses four wheels to grip the road, so it has a higher power transmission limit than two-wheel drive. In other words, this means that the engine driving force is large,
For example, if the vehicle is in two-wheel drive when the vehicle is in low gear and the accelerator is opened at a large angle, such as when starting, the engine's driving force cannot be completely transmitted to the road surface, and in extreme cases, slipping may occur. However, with four-wheel drive, this phenomenon is less likely to occur and the engine driving force can be used more effectively.

For example, in an automatic transmission that has a torque converter that transmits the driving force of the engine to the transmission via fluid, torque is increased in the low speed range by the action of the stator, which is a characteristic function of the torque converter. As vehicle speed increases, engine driving force is transmitted to the transmission through a coupling mechanism. Therefore, in the low speed region,
The driving force increases due to the torque increasing effect. Also,
Compared to 4-wheel drive, 2-wheel drive has a lower driving force transmission limit, which is the limit value of the driving force that can completely transmit the engine's driving force to the road surface against the frictional force of the road surface, so in extreme cases This will result in a slip condition.

[Problems to be Solved by the Invention] Conventionally, in order to automatically switch between two-wheel drive and four-wheel drive, the engine accelerator opening, wiper operation/non-operation, and brake operation/non-operation are detected. , a method using a combination of these detection signals is proposed.

However, such a detection signal does not necessarily represent the torque state of the vehicle, and it is difficult to say that accurate switching control is performed.

Therefore, the present invention focused on the coupling point that starts the coupling mechanism of the torque converter, and developed a two-wheel drive/four-wheel drive system that can automatically switch between two-wheel drive and four-wheel drive using appropriate torque.
The purpose is to provide a four-wheel drive automatic switching device.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an automatic transmission having a torque converter with a switching mechanism for switching between two-wheel drive and four-wheel drive. The two-wheel drive/four-wheel drive automatic switching device includes an accelerator opening detection section that detects the accelerator opening of the engine, a gear speed detection section that detects the number of transmission gears, and a vehicle speed detection section that detects the actual vehicle speed signal. a detection unit; a storage unit that stores an ideal vehicle speed signal indicating a coupling point of the torque converter set based on the accelerator opening degree and the number of gears; and a storage unit that stores the signals from the accelerator opening degree detection unit and the gear position number detection unit; an arithmetic processing unit that reads the ideal vehicle speed signal into the storage unit and calculates the ideal vehicle speed signal, and compares the ideal vehicle speed signal calculated by the arithmetic processing unit with the actual vehicle speed signal detected by the vehicle speed detection unit. When the actual vehicle speed signal is larger than the ideal vehicle speed signal, the two-wheel drive signal is transmitted to the switching mechanism, and when the actual vehicle speed signal is smaller than the ideal vehicle speed signal, the four-wheel drive signal is transmitted to the switching mechanism. It has a configuration consisting of a comparison and determination section that outputs output to the.

[Operations and Effects of the Invention] With the above configuration, the present invention includes an accelerator opening detection section and an The ideal vehicle speed signal is calculated by reading the signal from the gear shift number detection section, and switching between 2-wheel drive and 4-wheel drive is performed by comparing it with the actual vehicle speed signal. The slip condition that occurs due to the increase in torque can be reduced by 4, which has a high driving force transmission limit.
This is prevented by switching to wheel drive, and in high-speed coupling conditions, switching to two-wheel drive, which is more fuel-efficient. Therefore, by switching between 2-wheel drive and 4-wheel drive at the coupling point of the torque converter, it is possible to prevent a slip condition at the time of starting, to enable switching with an appropriate torque, and to realize driving with good fuel efficiency. I can do it.

〔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, and FIG. 2 is a diagram showing a graph at full throttle in a vehicle having a drive device with an automatic transmission. be.

In FIG. 1, 1 is an accelerator opening detection section, 2
3 indicates a gear stage number detection section, 3 indicates an arithmetic processing section, 4 indicates a storage section, 5 indicates a vehicle speed detection section, and 6 indicates a comparison determination section. The storage unit 4 stores an ideal 2-wheel drive/4-wheel drive switching point indicating the coupling point of the torque converter set based on the accelerator opening x and the number of gears y, and stores the ideal 2-wheel drive/4-wheel drive switching point. The value of the vehicle speed signal, V _xy , is stored in matrix form. During actual driving, the calculation processing unit 3 reads the accelerator opening x and the number of gears y at each point in time, and calculates the vehicle speed value V _xy at the switching point corresponding to the combination of the accelerator opening x and the number of gears y. Take it out from the storage unit 4. Then, the determination processing unit 6 reads the actual vehicle speed signal V _p and compares the vehicle speed value V _xy at these switching points with the actual vehicle speed signal V _p , so that the actual vehicle speed signal V _p is the vehicle speed value V _xy at the switching point. If it is larger than , the two-wheel drive signal is used, and conversely, the actual vehicle speed signal V _p is used as the vehicle speed value V _xy at the switching point.
If the value is smaller than , a four-wheel drive signal is output.
This output signal controls the two-wheel drive/four-wheel drive switching mechanism. Therefore, if the 2-wheel drive/4-wheel drive switching mechanism switches between 2-wheel drive and 4-wheel drive based on operation/non-operation, 2-wheel drive and 4-wheel drive are switched by an inversion signal, In other words, only a signal indicating whether or not it is two-wheel drive or four-wheel drive is sufficient.

As shown in FIG. 2, the vehicle speed value V _xy at the switching point corresponding to the combination of the accelerator opening degree x and the number of gears y stored in the storage unit 4 is determined by the engine driving force characteristic curve corresponding to each number of gears. , the ideal two-wheel drive/four-wheel drive switching points A to D at each gear stage can be determined from the driving force limit values of two-wheel drive and four-wheel drive. Here, switching points A to D are coupling points of the torque converter, and four-wheel drive is selected on the lower speed side of each point, and two-wheel drive is selected on the higher speed side of each point. Second
The graph shown in the figure is the driving force characteristic curve at full throttle, that is, when the accelerator opening is 100%.
Since the torque level changes when the accelerator opening changes, the graph in FIG. 2 also changes depending on the accelerator opening. Therefore, each switching point A~
D also varies depending on the accelerator opening degree.

In other words, the ideal switching point between two-wheel drive and four-wheel drive is determined according to the accelerator opening x and the number of gears (1st, 2nd, etc.) y, and represents the switching point at that time. As a specific numerical value, as is clear from FIG. 2, vehicle speed signals corresponding to each point can be used.

As is clear from the above explanation, according to the present invention, the torque ratio is particularly high at low gears.
Because wheel drive and four-wheel drive can be switched automatically at ideal points, engine drive power is effectively transmitted, which not only provides excellent economic efficiency but also improves driving sensation.
Good running stability etc. can be maintained.

[Brief explanation of the drawing]

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, and FIG. 2 is a diagram showing a graph at full throttle in a vehicle having a drive device with an automatic transmission. be. 1... Accelerator opening detection section, 2... Gear stage number detection section, 3... Arithmetic processing section, 4... Storage section, 5...
Vehicle speed detection section, 6... comparison determination section.

Claims (1)

[Scope of Claims] 1. Two-wheel drive/four-wheel drive equipped with a switching mechanism for switching between two-wheel drive and four-wheel drive, which is provided in an automatic transmission having a torque converter.
The automatic wheel drive switching device includes: an accelerator opening detection section that detects the accelerator opening of the engine; a gear speed detection section that detects the number of transmission gears; a vehicle speed detection section that detects an actual vehicle speed signal; a storage section that stores an ideal vehicle speed signal indicating a coupling point of the torque converter set based on the opening and the number of gears; and signals from the accelerator opening detection section and the number of gears detection section are read into the storage section. an arithmetic processing unit that calculates the ideal vehicle speed signal; and a calculation processing unit that compares the ideal vehicle speed signal calculated by the arithmetic processing unit and the actual vehicle speed signal detected by the vehicle speed detection unit, and calculates the actual vehicle speed signal. a comparison determination unit that outputs a two-wheel drive signal to the switching mechanism when the vehicle speed signal is larger than the ideal vehicle speed signal, and outputs a four-wheel drive signal to the switching mechanism when the vehicle speed signal is smaller than the ideal vehicle speed signal; A two-wheel drive four-wheel drive automatic switching device characterized by comprising: