Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2000-12-21
2002-08-20
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C307S010800, C362S466000, C362S467000
Reexamination Certificate
active
06438478
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an automatic leveling system for adjusting optical axes of atutomotive headlamps based on a pitch angle of a vehicle, and more particularly to an automatic leveling system for vertically adjusting optical axes of headlamps based on a pitch angle of a stationary vehicle.
BACKGROUND OF THE INVENTION
A headlamp of the type used in an automatic leveling system is constructed such that a reflector with a light source securely inserted therein is supported to tilt about a horizontal tilting axis relative to a lamp body. An actuator is used to tilt the optical axis of the reflector (a headlamp) about the horizontal tilting axis.
A conventional automatic leveling system is constituted by a pitch angle detecting means, a vehicle speed sensor, and a control part for controlling the driving of actuators based on detection signals from the detecting means and the sensor, which are provided on a vehicle. The optical axes of headlamps (reflectors) are adjusted to remain in a certain position relative to the surface of a road at all times.
The conventional automatic leveling system automatically levels the headlamps in real-time, such as when a vehicle posture changes because of acceleration or deceleration or when the load is loaded or unloaded, or the passengers get in or out of the vehicle. This increases the operations of the actuators, leading to greater power consumption. Moreover, a high durability is required for driving mechanism components such as motors and gears, which leads to greater production costs.
To provide an automatic leveling system that can reduce the frequency of use of actuators and that is inexpensive and durable, an automatic leveling system was proposed (Japanese Patent Application No.10-274859) in which actuators are driven at predetermined intervals (ten second intervals) while a vehicle is at a stop.
However, while the actuators of the above automatic leveling system are controlled based on a pitch angle detected during a predetermined interval time, if an interval control coincides with the start of the vehicle, automatic leveling cannot be properly performed. The problem is described with reference to FIG.
6
.
FIG. 6
is a chart showing changes in vehicle speed and vehicle posture from the start of the vehicle until it reaches a constant running speed. As shown in the chart, it takes a predetermined length of time (T) before the vehicle actually starts running after an accelerator pedal is depressed. In other words, the vehicle speed starts increasing after the predetermined length of time (T) has elapsed. Because of this, the vehicle sensor detects the start of the vehicle at a predetermined start detection delay time T after the accelerator pedal is depressed.
As to the vehicle posture, when the accelerator pedal is depressed, a rear part of the vehicle first lowers and the vehicle continues to remain in that state. That is, when the vehicle sensor detects the start of the vehicle (when a control part detects the start of the vehicle based on an output from the vehicle sensor), the rear part of the vehicle is in a lowered position or, alternatively, the front part of the vehicle is in a raised position.
Because of this, as shown in
FIG. 6
, there may be a case where the timing of an interval control falls within (T), a time period between the lowering of the rear part of the vehicle by the depression of the accelerator pedal and the detection of the start of the vehicle by the vehicle speed sensor. A vehicle pitch angle for use for interval control in this case is improper because the pitch angle is calculated based on the vehicle's lowered position. The control part is forced to control the actuators based on the improper pitch angle data.
An object of the present invention is to provide an automatic leveling system for automotive headlamps that is inexpensive and that can provide a longer service life by reducing the frequency of use of actuators by controlling the actuators at predetermined intervals. Another object of the invention is to provide an automatic leveling system adapted to operate properly even if the timing of interval control coincides with the start of the vehicle.
SUMMARY OF THE INVENTION
According to a first embodiment of the invention, an automatic leveling system for automotive headlamps comprises headlamps optical axes adapted to tilt vertically relative to a body of a vehicle by driving actuators, a control means for controlling the driving of the actuators, a vehicle speed detecting means for detecting speeds of the vehicle, a pitch angle detecting means for detecting pitch angles of the vehicle and a storage part for storing pitch angle data of the vehicle detected by the pitch angle detecting means. The control means controls the actuators based on the pitch angle data detected by the pitch angle detecting means such that the optical axes of the headlamps are tilted in a certain tilted angle relative to a road surface.
The storage part is configured to store a plurality of data detected at predetermined time intervals.
The control means is configured to control the actuators based on pitch angle data not affected by a change in posture of the vehicle when the vehicle is started and the interval control is carried out substantially at the same time. The control means controls the actuators at predetermined intervals based on the latest pitch angle data.
Additionally, according to a second embodiment of the invention, an automatic leveling system for automotive headlamps is provided such that the start of the vehicle is detected by the vehicle speed detecting means within a predetermined set time after an interval control of the actuators is carried out. The control means determines that the interval control and the start of the vehicle substantially coincide with each other.
Furthermore, according to a third embodiment of the invention, an automatic leveling system for automotive headlamps is provided such that the predetermined set time, which is used to determine whether the interval control and the start of the vehicle coincide with each other, isequal to or longer than a vehicle start detection delay time, which is a time from an accelerator pedal is depressed until the vehicle speed detecting means detects the start of the vehicle.
Pitch angle data generated while the vehicle is at a stop are more accurate than pitch angle data generated while the vehicle is running because there are less disturbing factors when the vehicle is stationary. Since the actuators is controlled based on the more accurate pitch angle data, a more accurate automatic leveling can be provided with the former pitch angle data.
In addition, since the control of the actuators is limited to a certain time interval, the frequency at which the actuators are driven is reduced to that extent. Thus, power consumption is reduced and the wear on the driving mechanism is reduced.
Moreover, the start of the vehicle may be detected by the vehicle speed sensor. If an interval control coincides with the start of the vehicle the actuators may be driven based on an improper pitch angle. A proper automatic leveling can be effected by controlling the actuators based on a proper pitch angle obtained before the depression of the accelerator pedal.
Referring to
FIG. 6
, a proper automatic leveling process is described in detail. If an interval control of the actuators happens substantially at the same time that the vehicle starts,that is, if an interval control falls within a vehicle start detection delay time T (from the time the accelerator pedal is depressed until the vehicle speed sensor detects the start of the vehicle), a pitch angle used for this specific interval control is that detected by the pitch angle detection means when the interval control occurs. Hence, there may be a risk that the pitch angle data so detected include data generated when the vehicle is lowered when it is about to start. Therefore, the pitch angle data may not be necessarily proper for use. That is, the actuators (automatic leve
Takeuchi Hideaki
Toda Atsushi
Cuchlinski Jr. William A.
Fish & Richardson P.C.
Hernandez Olga
Koito Manufacturing Co. Ltd.
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