Patent Application
20070120494
1. Technical Field
The invention relates to vehicle lighting control and more particularly to a system allowing selective, and automatic, operation of a vehicle's exterior lamps in daytime running mode.
2. Description of the Problem
Selected exterior vehicle lights, particularly headlamps, can be operated in the daytime to increase the visibility of the vehicle to others. Such operation is referred to as daytime running light (DRL) operation. DRL operation of vehicle lamps may involve illumination of the headlamps at reduced power to reduce the load on the vehicle electrical system and extend the life of the headlamp bulbs as compared with full power operation. However, whether the lights are operated at reduced power settings or not, DRL operation of the lamps represents a non-negligible electrical load which increases fuel usage and reduces lamp service life. It would be desirable to limit DRL operation to periods when actually required.
A simplistic approach to the issue might conclude that DRL operation can be limited to when the vehicle is in motion. However, state and provincial law may control DRL operation for school busses, particularly when embarking and disembarking pupils. Such requirements may differ depending upon key ignition status, parking brake status and whether pupil warning lights are activated or not. For example, it is clear that a vehicle should not be in motion when the parking brake is set, however, state requirements may stipulate that the daytime running light operation is required at any time that the pupil warning lights are operating and may require parking brakes be set when children are present.
The invention provides a lighting control system implementing daytime running light operation, tailored to meet jurisdictional requirements. Daytime running light operation is triggered in response to selected vehicle conditions, typically including at a minimum, ignition key position, release of the park brake, engine operational status and status of pupil warning lights. In a school bus the headlamps are operated in a daytime running light mode unless such operation is canceled or suspended. Cancellation occurs in response to selected conditions being met or no longer holding true.
Additional effects, features and advantages will be apparent in the written description that follows.
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
Referring now to the figures and in particular to
Referring now to
DRL operation is implemented by electrical system controller 30 depending upon the status of various vehicle systems and switches. DRL operation here is taken to mean operation of the lowbeams of vehicle headlamps 61, 48, potentially at reduced output levels, by control of the switching state of lowbeam FET 53. Low Beam FET 53 is one of a plurality of power field effect power (FET) switching transistors 51, 52, 53, 54, 55, 56, 57 and 58, most of which are employed to turn vehicle exterior lights on and off. In particular FET 51 is connected to drive a warning arm positioning motor coil 36, park light FET 52 is connected to drive assorted marker, park and tail lights 37, 38, FET 55 is connected to drive the right turn signal lamps 43, FET 56 is connected to drive left turn signal lamps 64 and FET 57 is connected to drive the brake lamps 45 and FET 58 is connected to illuminate the pupil boarding warning lamps 16.
Microprocessor 31 is conventionally programmed as a microcontroller. The programming directs responses to various status indications and switch inputs, whether directly received, or decoded from messages broadcast over the controller area network, or received over other datalinks, such as a SAE J1708 serial datalink through datalink interface 39. Because of the availability of status inputs from various sources to microprocessor 31, DRL operation can be closely tied to operating conditions indicated by the inputs. The particular inputs of interest here are an engine running message generated by the engine controller 20, the status of a warning light switch determined by the ESC 30 from switches 38 or steering wheel switches 24, ignition status from ignition 138, and park brake 140 status. The status of park brake 140 and ignition 138 are applied directly to the ESC 30.
As an initial matter, DRL operation is not called for if headlamps are turned on in response to closure of headlight microswitches 45. Otherwise, DRL operation begins with meeting selected conditions. The conditions to be monitored are: (1) ignition (26 or 138) status; (2) warning light active status; (3) engine running status; and (4) park brake status.
The present invention, in a preferred embodiment, allows modifying DRL operation, such as to disable DRL operation of the headlamps when the vehicle is not in motion, unless the vehicle is used as a school bus and is embarking or disembarking pupils. During passenger loading and unloading a school bus operator will engage warning lights 16 and extend a signal arm. Accordingly, microprocessor 31 may be programmed to discontinue DRL operation in response to setting the parking brake unless warning lights have been turned on. Warning lights may be turned on using a switch in a switch pack 38 connected to the microprocessor by an SAE J1708 datalink (or equivalent), or, by use of steering wheel switches 24 where such switches have been modified to implement warning functions.
Referring now to
While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.
