JPH0664457A - Vehicle differential controller - Google Patents

Abstract

(57) [Summary] [Purpose] Switching to four-wheel drive and the difference between them are used to eliminate unnecessary vehicle height signal fluctuations to eliminate erroneous road erroneous judgments and to judge bad roads according to running conditions. Dynamic control effectively. [Structure] A sampling cycle of a vehicle height signal in the vehicle height sampling means 7 is changed according to a vehicle speed. The vehicle height signal sampled by the vehicle height sampling means 7 is given to the rough road determination means 8. In the rough road determination means 8, the vehicle height signal is differentiated and compared with the threshold value of the vehicle speed fluctuation, and the number of times the differential signal exceeds the threshold value is counted by the counter CNT. And
The rough road degree is determined according to the count number of the counter CNT counted within the determined determination time. At this time, the threshold value and the determination time are changed according to the vehicle speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle differential control device suitable for use in a four-wheel drive vehicle.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a four-wheel drive switching control device disclosed in Japanese Utility Model Laid-Open No. 3-27863. In the figure, 12 is a vehicle height sensor, 12a is the highest level transmitter, 12b is the lowest level transmitter, 13 is a computing means,
14 is a vehicle height determination means, 15 is a timer, 16 is a counter,
Reference numeral 17 is a four-wheel drive switching means. In this four-wheel drive switching control device, the first reference value (maximum level) representing the vehicle height higher than the vehicle height in the stationary state is stored in the highest level transmitter 12a, and represents the vehicle height lower than the vehicle height in the stationary state. The second reference value (lowest level) is stored in the lowest level transmitter 12b. The digital signals output from the highest level transmitter 12a and the lowest level transmitter 12b are calculated by the calculating means 1
It is processed in 3 and sent to the vehicle height determination means 14. The vehicle height determination means 14 outputs a determination signal when the amount of change in vehicle height detected by the vehicle height sensor 12 becomes larger than between the first reference value and the second reference value. This determination signal is the counter 16
Given to. The counter 16 counts the number of determination signals input within a fixed time measured by the timer 15, and when the determination signals are counted by a predetermined number or more, it is determined that the vehicle is traveling on a rough road, and the four-wheel drive switching means. An operation signal is output to 17. As a result, the conventional two-wheel drive can be switched to the four-wheel drive that excels in driving safety.

[0003]

However, according to such a conventional four-wheel drive switching control device, if the vehicle height vibrates finely for an extremely short time, it may be erroneously determined as a bad road. was there. Further, even on the same rough road, the fluctuation cycle and fluctuation width of the vehicle height change depending on the vehicle speed. Therefore, the number of times that the vehicle height change amount becomes larger than between the first reference value and the second reference value within a certain period of time varies depending on the traveling speed. That is, conventionally, there is a problem that the vehicle speed is not considered at all, the possibility of determining a bad road varies greatly, and the bad road is not determined according to the running state.

The present invention has been made in order to solve such a problem, and its object is to eliminate unnecessary fluctuations of the vehicle height signal to eliminate erroneous road misjudgment, and to adapt to the running condition. Another object of the present invention is to provide a differential control device capable of effectively performing switching to four-wheel drive and differential control thereof for performing rough road determination.

[0005]

In order to achieve such an object, the present invention distributes and transmits a driving force from an input section to first and second output sections in which a differential is allowed. A vehicle differential control device including a differential mechanism and a differential limiting mechanism that generates a differential resistance force between a first output portion and a second output portion to limit the differential amount of the vehicle. Vehicle height detecting means for outputting a vehicle speed signal, vehicle speed detecting means for detecting a vehicle speed and outputting a vehicle speed signal, and vehicle speed detecting means at a sampling cycle that changes according to the vehicle speed signal from the vehicle speed detecting means. Vehicle height sampling means for sampling a high signal,
A bad road judging means for judging the degree of a bad road on the basis of a vehicle height signal sampled by the vehicle height sampling means and a judgment parameter changing according to the vehicle speed signal from the vehicle speed detecting means, and the bad road judging means. And a differential limiting control means for controlling the differential resistance force of the differential limiting mechanism based on the result of the determination.

[0006]

Therefore, according to the present invention, the sampling period of the vehicle height signal changes according to the vehicle speed signal. For example,
The sampling cycle of the vehicle height signal changes such that it is short at high speed and long at low speed. Then, the degree of the rough road is determined based on the sampled vehicle height signal and the determination parameter that changes according to the vehicle speed signal.

[0007]

EXAMPLES The present invention will now be described in detail based on examples.

FIG. 1 is a block diagram of a differential control device showing an embodiment of the present invention, and FIG. 2 is a diagram showing each section in this block diagram in more detail.

In the figure, 1 is an input unit, 2 and 2 are drive output units for front and rear wheels in which a differential is allowed, and 3 is an engine 10 input from the input unit 1 via a transmission 11.
4 is a differential mechanism that distributes and transmits the power of the drive to the drive output units 2 and 2, and 4 is a differential limiting mechanism that generates a differential resistance output between the drive output units 2 and 2 to limit the differential amount. Is a vehicle height detecting means for detecting a vehicle height and outputting an analog detection signal (vehicle height signal), 6 is a vehicle speed detecting means for detecting a vehicle speed and outputting an analog detection signal (vehicle speed signal), and 7 is a vehicle speed detection A vehicle height sampling means for sampling the vehicle height signal from the vehicle height detecting means 5 at a sampling cycle which changes according to the vehicle speed signal from the means 6, and 8 is a vehicle height signal from the vehicle height sampling means 7 (hereinafter, vehicle height sampling Of the rough road based on the difference signal and the determination parameter (threshold value, determination time) that changes according to the vehicle speed signal from the vehicle speed detection means 6. Rough road judging means for judging the degree (rough road degree) 9 is a differential limiting control means for controlling the differential resistance to be generated by the differential limiting mechanism 4 according to the determined rough road index at the bad road judging means 8.

The vehicle height sampling means 7 comprises a storage table TB1 indicating the relationship between the vehicle speed and the sampling period, and a timer T1 for driving the switch SW1 at the sampling period determined with reference to the storage table TB1.

The rough road judging means 8 comprises a difference means DM for making a difference between vehicle height sampling signals, a storage table TB2 showing the relationship between the vehicle speed and a threshold value (vehicle height variation), and a difference means D.
A comparator CP that compares the difference signal from M with a threshold value determined with reference to the storage table TB2 and outputs a comparison signal when the difference signal exceeds the threshold value, and the comparator CP that outputs the comparison signal A counter CNT that counts the number of comparison signals, a storage table TB3 that shows the relationship between the vehicle speed and the determination time, and a timer T2 that resets the count value of the counter CNT at each determination time determined with reference to this storage table TB3. , And a storage table TB4 showing the relationship between the count number of the counter CNT and the rough road degree.

The differential limitation control means 9 stores a storage table TB5 indicating the relation between the rough road degree output from the rough road determination means 8, that is, the rough road degree determined with reference to the storage table TB4 and the differential resistance. I have it.

In such a structure, the vehicle height sampling means 7 refers to the storage table TB1 to lengthen the sampling cycle of the vehicle height signal during low speed traveling and shorten the sampling cycle of the vehicle height signal during high speed traveling. As a result, the frequency range of vehicle height fluctuations targeted by the rough road determination means 8 changes, and fluctuations in the vehicle speed signal unnecessary for rough road determination are removed.

The rough road judging means 8 makes a difference between the vehicle height sampling signals from the vehicle height sampling means 7 and a difference signal of the vehicle height sampling signals and a threshold value of the vehicle height fluctuation determined by referring to the storage table TB2. Are compared by the comparator CP, and when the difference signal exceeds the threshold value, the comparator CP
The comparison signal output by the counter is counted by the counter CNT. Then, the rough road degree is determined with reference to the storage table TB4 in accordance with the count number in the counter CNT counted within the determination time determined with reference to the storage table TB3. At this time, the threshold value and the determination time change according to the vehicle speed. That is, the storage tables TB2 and TB3
With reference to, the threshold value and the determination time are set large when the vehicle runs at a low speed, and the threshold value and the determination time are set small when the vehicle travels at a high speed. As a result, the rough road is determined according to the running state of the vehicle. That is,
The bad road determination is performed in consideration of the vehicle height variation that slowly and largely fluctuates when traveling at low speed, and the vehicle height variation that quickly and slightly fluctuates when traveling at high speed.

The differential limiting control means 9 obtains a differential resistance force with reference to the memory table TB5 according to the bad road degree output from the rough road determination means 8 and makes a difference so as to generate this differential resistance force. The motion limiting mechanism 4 is controlled. As a result, the differential amount between the drive output units 2 and 2 is limited according to the degree of the rough road,
Switching to four-wheel drive and its differential control are effectively performed.

When the vehicle goes out of the rough road, the count of the counter CNT within the judgment time of the rough road judging means 8 decreases, so that the degree of the bad road is judged to be small and the differential limitation is automatically released. To be done.

[0017]

As is apparent from the above description, according to the present invention, the sampling cycle of the vehicle height signal is changed according to the vehicle speed signal, so that unnecessary fluctuations of the vehicle height signal are eliminated. As a result, when the vehicle height vibrates finely for an extremely short time, it is possible to prevent the vehicle from being erroneously determined as a bad road. Further, since the degree of the bad road is determined based on the sampled vehicle height signal and the determination parameter that changes according to the vehicle speed signal, the influence of the vehicle speed is taken into consideration in the bad road determination, and depending on the traveling state. Switching to four-wheel drive and its differential control are effectively performed.

[Brief description of drawings]

FIG. 1 is a block diagram of a differential control device showing an embodiment of the present invention.

FIG. 2 is a block diagram showing each unit in FIG. 1 in more detail.

FIG. 3 is a block diagram of a conventional four-wheel drive switching control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input part 2 Drive output part 3 Differential mechanism 4 Differential limiting mechanism 5 Vehicle height detecting means 6 Vehicle speed detecting means 7 Vehicle height sampling means 8 Bad road judging means 9 Differential limiting control means

Claims (1)

[Claims] 1. A differential mechanism that distributes and transmits a driving force from an input section to first and second output sections that are allowed to differential, and a differential mechanism between the first and second output sections. In a vehicle differential control device equipped with a differential limiting mechanism that generates a resistance force and limits the differential amount, a vehicle height detecting means for detecting a vehicle height and outputting a vehicle height signal, and a vehicle speed detecting means. Vehicle speed detecting means for outputting a vehicle speed signal, vehicle height sampling means for sampling the vehicle height signal from the vehicle height detecting means at a sampling cycle which changes according to the vehicle speed signal from the vehicle speed detecting means, and this vehicle height sampling means A bad road determination means for determining the degree of a bad road based on a vehicle height signal sampled by the vehicle speed signal and a determination parameter that changes according to the vehicle speed signal from the vehicle speed detection means; Based on the differential Differential control device for a vehicle, characterized in that it comprises a differential limiting control means for controlling the differential resistance of the limit mechanism.