Illumination – Supported by vehicle structure – Condition responsive
Reexamination Certificate
1999-06-16
2001-02-27
O'Shea, Sandra (Department: 2875)
Illumination
Supported by vehicle structure
Condition responsive
C362S460000, C362S464000, C362S465000, C362S037000, C362S276000
Reexamination Certificate
active
06193398
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application relates to and incorporates herein by reference Japanese Patent Applications No. 10-167626, No. 10-244782, No. 11-107851, No. 11-107852 and 11-107853 filed on Jun. 16, 1998, Aug. 31, 1998, Apr. 15, 1999, Apr. 15, 1999 and Apr. 19, 1999, respectively.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle headlight optical axis direction adjusting system for automatically adjusting the optical axis direction of irradiation of a headlight provided for a vehicle.
2. Description of Related Art
Conventionally, in the headlight of a vehicle, when the optical axis of the a headlight is directed upward due to inclination of the chassis of the vehicle, glare is given to an on-coming vehicle or the like. When the optical axis is directed downward, a driver of the vehicle may lose the far field of view. There has been, consequently, a demand for holding the optical axis direction of the headlight unchanges as much as possible.
JP-A-9-301055 discloses a vehicle headlight optical axis control system, in which a control mode is set in accordance with acceleration, a filtering process is executed when the acceleration is smaller than a predetermined value, the filtering process is not performed so as not to delay switching of the control mode when the acceleration is equal to or larger than the predetermined value, and the optical axis direction of the headlight is adjusted on the basis of a change in the height of the vehicle on each occasion.
In the above system, when the acceleration of the level which can not be reached in a normal driving state is sensed in association with a known traction (TRC) control or antilock brake (ABS) control, since the acceleration is equal to or larger than the predetermined value, the filtering process is not performed and the control mode is frequently switched. At the time of acceleration associated with the TRC control (TRC control time) or at the time of deceleration associated with the ABS control (ABS control time), although the acceleration largely changes, the vehicle posture does not change so much. As a result, the optical axis is improperly controlled when the direction of the optical axis of the headlight is allowed to follow changes in the acceleration at such time.
Another optical axis control system is known which uses an inclination angle obtained by approximating an amount of change in the vehicle posture caused by loading to a linear expression. According to this control, the optical axis direction of the headlight can be made to coincide with the vehicle posture under a limited loading condition such as “only occupant load” or “occupant load and up to 50 kg of trunk load”. However, various loading conditions of combination of the occupant load and the trunk load can not be dealt with.
In a still another system, a vehicle height sensor is installed only on either the right or left side of a rear wheel since front wheels are wheels to be steered and an installation space is limited. A front height value is estimated on the basis of a rear height value in the stop mode of the vehicle to calculate the inclination angle. When the vehicle is stopped riding on a block or the like, a rear height value different from that on a flat road is sensed. In one trip (a driving interval between stops of the vehicle) after that, there is consequently an inconvenience such that a computation error occurs in the inclination angle in the longitudinal direction of the vehicle and the optical axis direction of the headlight is deviated. Since the rear height value changes due to turning which is a rotary motion around the longitudinal axis of the vehicle during a turn although the vehicle is not inclined in the longitudinal direction, a computation error occurs in the inclination angle in the longitudinal direction of the vehicle until the turn of the vehicle is finished and there is an inconvenience such that the optical axis direction of the headlight is accordingly deviated.
SUMMARY OF THE INVENTION
The present invention has an object to properly adjust the optical axis direction of a headlight in accordance with a driving state of a vehicle without frequently switching the optical axis direction of the headlight.
The present invention has another object to deal with various loading conditions in the event of automatically adjusting the optical axis direction of a headlight of a vehicle on the basis of an output of a single vehicle height sensor.
The present invention has a further object to properly correct a deviation in optical axis direction of a headlight when the vehicle is either stopped riding on a block or the like or is in a turn state.
According to one aspect of the present invention, an inclination angle in the optical axis direction of a headlight of a vehicle to the horizontal plane is calculated on the basis of output values from two vehicle height sensors arranged on the front and rear sides of the vehicle, respectively. A filter for changing the response of adjustment of the optical axis direction of the headlight is switched depending on a control mode determined in correspondence with a vehicle speed and acceleration. When the acceleration exceeds the highest determination level which is set so as not to be reached in a normal driving state, the control mode corresponding to the acceleration state or the deceleration state of the vehicle is continued unless a constant speed state of the vehicle continues for a predetermined period after that.
According to another aspect of the present invention, inclination angle in an optical axis direction of a headlight to the horizontal plane is calculated on the basis of an output value from a single vehicle height sensor by using a prediction expression which is divided into a plurality of regions of vehicle postures having different inclinations in accordance with loading conditions of an occupant load and a trunk load. The optical axis direction of the headlight is adjusted on the basis of the inclination angle. For example, by preparing the prediction expression divided into a plurality of regions of vehicle postures in accordance with the loading conditions of the occupant load and the trunk load in correspondence with the vehicle type and the like. Preferably, the inclination angle is calculated from both of the output of the single vehicle height sensor and an error which occurs in association with installation of the vehicle height sensor.
According to a further aspect of the invention, when it is determined that a driving mode of a vehicle is a stable driving mode, a reference inclination angle in the vehicle stop mode is updated based on an output of a vehicle height sensor, the inclination angle in the driving mode is corrected on the basis of the reference angle, and the optical axis direction of the headlight is thereby adjusted. When the vehicle once enters the constant speed driving mode before completion of one trip, irrespective of the presence or absence of a deviation in the optical axis direction of the headlight of the vehicle, the reference inclination angle in the vehicle stop mode is updated and the inclination angle in the driving mode is corrected. Thus, an effect such that even if the optical axis direction of the headlight is deviated, it can be properly adjusted is obtained.
REFERENCES:
patent: 4973155 (1990-11-01), Masuda
patent: 5195816 (1993-03-01), Moss et al.
patent: 5877680 (1999-03-01), Okuchi et al.
patent: 6010237 (2000-01-01), Gotou
patent: 6049749 (2000-04-01), Kobayashi
patent: 6109759 (2000-08-01), Tanabe et al.
patent: 9-290683 (1997-11-01), None
patent: 9-301055 (1997-11-01), None
Nishimura Ken-ichi
Okuchi Hiroaki
Alavi Ali
Denso Corporation
O'Shea Sandra
Pillsbury & Winthrop LLP
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