Vehicle electrical system

#The present invention relates to a system for controlling charging of a battery on a motor vehicle equipped with an internal combustion engine and using the battery for starting the engine.

#Lead acid batteries are the conventional source of power for cranking internal combustion engines installed on motor vehicles. Lead acid batteries also provide auxiliary power for components installed on such vehicles for use when the vehicle engine is not operating.

#Lead acid batteries operate chemically. The chemical reactions that produce current during discharge are not perfectly reversible during recharge nor are such batteries perfectly stable during periods of nonuse. A battery discharges several hundred amp-seconds during cranking of an engine. In conventional recharging systems developed for automotive applications, recharging occurs during the first few minutes after the engine begins running. Recharging is done more quickly than desirable because automobiles are often operated for short periods of time.

#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:

#FIG. 1 is a perspective view of a truck in partial cutaway illustrating a vehicle electrical system;

#FIG. 2 is a block diagram schematic of the vehicle electrical system incorporating an embodiment of the present invention;

#FIG. 1 is a perspective view of a vehicle 11 and of a vehicle electrical system 10 installed on the vehicle. Vehicle electrical system 10 comprises a control network based on a serial data bus 18. One node of bus 18 is an electrical system controller (ESC) 30, a type of programmable body controller, which controls various discrete devices, including a charging regulator 21 for a battery 25. ESC 30 also manages a number of vocational controllers connected to bus 18 as nodes. ESC 30 executes a battery charging management program which aims to keep the battery fully charged as well as controlling the charging regimen to extend battery service life beyond that normally seen in heavy duty truck operation. Vehicle electrical system 10 further includes power systems such as an alternator 15 and it includes voltage regulators 16, 21 and 22, which regulate the voltage on subsidiary electrical systems. The subsidiary electrical systems operate at different voltages. The subsidiary electrical systems include: a low voltage system for energizing lighting, etc.; an intermediate, controllable voltage level system for battery charging; and a high voltage level system providing power to fuel injectors.

#Active vehicle components are typically controlled by one of a group of autonomous, vocational controllers, which include an instrument and switch bank 12, a gauge cluster 14, and an engine controller 20, all of which, along with other local controllers, are connected to ESC 30 over serial data bus 18. The autonomous controllers include local data processing and programming and are typically supplied by the manufacturer of the controlled component. For each autonomous controller there is a defined set of variables used for communications between the autonomous controller and other data processing components on the network or attached to the network. Gauge cluster 14, and engine controller 20 all communicate with electronic system controller 30, which also monitors inputs received from the auxiliary instrument and switch bank 12 over the serial communication link in harness 18. Electronic system controller 30 may be programmed to override the normal response characteristics of the gauge cluster 14 and engine controller 20.

#Subsidiary electrical systems provide power for recharging battery pack 25, for illuminating electrical lamps 36 and for operating fuel injectors. Separate voltage regulators are provided for the distinct subsidiary systems, including a low voltage 19 for the electrical lamps 36 and a high voltage system 17 for the engine fuel injectors. Of particular interest here is a controllable voltage regulator 21 used for regulating the recharging of battery pack 25, which hangs from a vehicle side rail 13. The output voltage level of controllable voltage regulator 21 is controlled by a control signal from ESC 30, either directly, or over the network. In addition to executing a battery charging management program for determining the level of the control signal for the controllable voltage regulator 21, ESC 30 may execute subsidiary battery diagnostic routines, the results of which may be displayed on gauge cluster 14. ESC 30 may also demand increased engine output from engine controller 20 if required for maintaining, or optimal charging of, battery pack 25.