JPH0256246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a four-wheel drive switching control device for a part-time four-wheel drive vehicle that is capable of switching between two-wheel drive and four-wheel drive. It is.

2. Description of the Related Art Part-time four-wheel drive vehicles capable of switching between two-wheel drive and four-wheel drive have been developed in the past (see, for example, Japanese Utility Model Publication No. 55-54573) and are already in general use.

A part-time four-wheel drive vehicle like the one above is
Normally, a transfer clutch is provided in one of the two power transmission systems that transmit power from the output shaft of the power unit to the front wheels and the rear wheels, respectively.
Normally, switching between two-wheel drive and four-wheel drive is performed by controlling the transfer clutch by turning on and off a wheel drive select switch.

Problems to be solved by the invention The part-time four-wheel drive vehicle as described above is
The purpose of this system is to reduce slippage and enable safe and effective driving by switching to four-wheel drive on road surfaces or driving conditions where the wheels tend to slip. In devices where switching to 4-wheel drive is performed manually using a 4-wheel drive select lever or 4-wheel drive select switch, the driver cannot recognize that the road surface or driving conditions require switching to 4-wheel drive. If the vehicle is not equipped with a part-time 4-wheel drive, or if it is recognized but it is too troublesome to switch and the switching operation is not performed, the functions of a part-time 4-wheel drive vehicle will not be available. It is desirable to automate the process without relying on driver operation.

Therefore, for example, we can automatically switch to four-wheel drive using the on signal of the wiper switch in rainy weather, or use the switch to automatically switch to four-wheel drive during sudden acceleration or braking, such as when the accelerator pedal is fully depressed, and the switch to control the lighting of brake lights. A device has already been developed that automatically switches to four-wheel drive using an actuation signal from a pump switch or the like.

In addition to the above, the present invention automatically adjusts the
The purpose of the present invention is to provide a device that can switch to wheel drive so that part-time four-wheel drive vehicles can fully utilize their functions and drive safely.

Means for Solving the Problems The present invention provides a part-time four-wheel drive vehicle capable of switching between two-wheel drive and four-wheel drive, in which the vertical acceleration of the wheels, wheel support members, vehicle body, etc. A vertical acceleration sensor is provided that detects the vertical acceleration and converts the vertical acceleration into an electrical signal quantity, and when the frequency of the electrical signal quantity being equal to or higher than a predetermined value within a certain period of time exceeds a set value, a four-wheel drive switching sensor is provided. The vehicle is characterized by a control circuit that operates the actuator and generates an output signal to switch to four-wheel drive.

Function In the above configuration, when entering a rough road such as a gravel road or a bumpy road, the vertical acceleration becomes large, and the electrical signal amount of the vertical acceleration sensor exceeds a predetermined value, and at the same time, within a certain period of time, the electrical signal amount increases. When the frequency of driving over a predetermined value increases and exceeds the set value, the control circuit issues an output signal and automatically switches to four-wheel drive, improving the ability to drive on rough roads. When the vehicle enters a good road and the vertical acceleration becomes small, the frequency at which the electrical signal amount of the vertical acceleration sensor exceeds the predetermined value decreases and becomes below the set value.
The output signal of the control circuit is stopped and the vehicle automatically switches to two-wheel drive.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, 1 is a vertical acceleration sensor,
The vertical acceleration sensor 1 is configured to detect the vertical acceleration of the wheels, wheel support members, or vehicle body of a part-time four-wheel drive vehicle, and output this as a voltage signal A as shown in FIG. 2, for example. .

Voltage signal A of the vertical acceleration sensor 1 as described above
The voltage below the threshold voltage V _S is cut off by the threshold voltage setting circuit 2, and only the output corresponding to the voltage signal above the threshold voltage V _S (the shaded part in Fig. 2) is input to the integrating circuit 3. The integral value for a predetermined time t is input from the integrating circuit 3 to the comparator circuit 4, where the integral value is compared with a set voltage, and if the integral value exceeds the set value, the comparator circuit 4 inputs the integral value for a predetermined time t. outputs an output, the output of the comparator circuit 4 is held in the holding circuit 5, and the output of the comparator circuit 4 is held in the holding circuit 5.
A four-wheel drive switching actuator (for example, an electromagnetic solenoid) 7 is operated via the four-wheel drive switch, thereby automatically switching to four-wheel drive.

For example, when a vehicle enters a rough road from a normal speed on a good road, the vertical acceleration of the wheels increases and the frequency with which the vertical acceleration exceeds a certain predetermined value within a certain period of time also increases.

Therefore, as mentioned above, when the output signal of the vertical acceleration sensor 1 that exceeds the threshold setting value is integrated over a certain period of time t, the integrated value is the frequency at which the vertical acceleration exceeds the threshold setting value within that certain period of time. By comparing the integrated value with the set value in the comparator circuit 4, it is possible to accurately detect that the vehicle has entered a rough road driving condition.

In place of the integrating circuit 3, a counter is used to count the number of output signals from the threshold voltage setting circuit 2, and when the number exceeds a set value, the actuator 7 is actuated via the holding circuit 5 and the amplifier 6. It's okay.

In the illustrated embodiment, the holding circuit 5 is the comparator circuit 4
After the automatic switching to four-wheel drive is performed by the output from the comparator circuit 5, the four-wheel drive state is maintained for a certain period of time even if the output from the comparator circuit 5 disappears. This prevents too frequent switching from two-wheel drive to four-wheel drive and from four-wheel drive to two-wheel drive.

In addition, by configuring the threshold voltage setting circuit 2 so that the threshold voltage value can be variably controlled, the driver can arbitrarily set the threshold voltage value depending on the presence or absence of cargo or the driver's preference.
By changing the V _S , it is possible to improve the performance on rough roads and improve safety.

Although the above embodiment shows an example in which the vertical acceleration is converted into a voltage signal, it may be converted into a current signal.

Effects of the Invention As described above, according to the present invention, by using an extremely simple device to detect driving on a rough road and automatically switching to four-wheel drive, the four-wheel drive There is no need to switch to 4-wheel drive, and the ability to drive on rough roads can be improved, and the device of the present invention can be combined with a conventional device that automatically switches to 4-wheel drive during rainy weather, sudden acceleration, and braking. By doing so, it is possible to automate most of the switching between two-wheel drive and four-wheel drive in part-time four-wheel drive vehicles, and it is possible to achieve a higher level of safety improvement, which has a great practical effect. It's something you get.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a diagram explaining the function of a threshold voltage setting circuit for the output signal of the vertical acceleration sensor of FIG. 1. 1...Vertical acceleration sensor, 2...Threshold voltage setting circuit, 3...Integrator circuit, 4...Comparison circuit, 5...
Holding circuit, 7...4-wheel drive switching actuator.

Claims (1)

[Claims] 1. In a part-time four-wheel drive vehicle that is capable of switching between two-wheel drive and four-wheel drive, the vertical acceleration of the wheels, wheel support members, vehicle body, etc. is detected and the vertical acceleration is electrically converted. A vertical acceleration sensor for converting into a signal amount is provided, and when the frequency of the electrical signal amount of the vertical acceleration sensor exceeding a predetermined value within a certain period of time exceeds a set value, a four-wheel drive switching actuator is actuated. 1. A four-wheel drive switching control device for a part-time four-wheel drive vehicle, comprising a control circuit that issues an output signal for switching to wheel drive.