Vehicle electrical system

Details Vehicle electrical system Vehicle electrical system

1999-07-16

2001-12-04

Paladini, Albert W. (Department: 2841)

Electrical transmission or interconnection systems

Vehicle mounted systems

C307S010100, C340S315000, C701S049000

Reexamination Certificate

active

06326704

ABSTRACT:

FIELD OF THE INVENTION
This invention is in the general field of wiring systems applied to vehicles and particularly to motor vehicles such as automobiles. It specifically addresses the use of a common wire bus or data bus for a plurality of sensors and actuators in a motor vehicle.
BACKGROUND OF THE INVENTION
It is not uncommon for an automotive vehicle today to have many motors, other actuators, lights etc., controlled by one hundred or more switches and fifty or more relays and connected together by almost five hundred meters of wire, and close to one thousand pin connections grouped in various numbers into connectors. It is not surprising therefore that the electrical system in a vehicle is by far the most unreliable system of the vehicle and the probable cause of most warranty repairs.
Unfortunately, the automobile industry is taking a piecemeal approach to solving this problem when a revolutionary approach is called for. Indeed, the current trend in the automotive industry is to group several devices of the vehicle's electrical system together which are located geometrically or physically in the same area of the vehicle and connect them to a zone module which is then connected by communication and power buses to the remainder of the vehicle's electrical system. The resulting hybrid systems still contain substantially the same number and assortment of connectors with only about a 20% reduction in the amount of wire in the vehicle.
OBJECTS OF THE INVENTION
Accordingly, it is an object of the present invention to provide a new and improved electrical wiring system for coupling sensors and actuators in a motor vehicle in order to reduce the amount of wire in the motor vehicle.
Another object of the present invention is to provide an improvement over the zone module system used in prior art applications and render the zone module system obsolete.
Additional objects of this invention include to provide a vehicle wiring system including:
one or more switches having contact surfaces which are not eroded over the life of the contact after many makes and breaks, i.e., closing of the switch and opening of the switch, respectively;
one or more relays having contact surfaces which are not eroded over the life of the contact after many makes and breaks;
a network comprising various safety devices such as crash sensors and airbag inflator igniters
one or more connectors which maintain good contact quality over the life of the connector even after being disassembled numerous times and soaked with water and other fluids;
a coating for contact surfaces of the vehicle wiring system which contains abrasive particles and which results in a reduction in the contact resistance; and
one or more switches, relays or connectors with lower contact resistance for use in the automotive environment.
SUMMARY OF THE INVENTION
In order to achieve the objects set forth above and others, in one embodiment of a vehicle electrical wiring system in accordance with the invention, most if not all of the devices are connected together with a single communication bus and a single power bus. In the preferred case, a single wire pair will serve as both the power and communication buses. When completely implemented, each device on the vehicle will be coupled to the power and communication buses so that they will now have an intelligent connection and respond only to data that is intended for that device, that is, only that data with the proper device address. Although initially a network coding and decoding chip will be expensive, when there are one hundred or more per vehicle, for example, the cost can be expected to drop to where it is more than covered by the cost savings in vehicle wiring assembly. Similar chips are in fact now in production for use in wiring buildings as part of the LonWorks network by Echelon Corporation of Palo Alto, Calif. In particularly advantageous embodiments, the devices include at least one accelerometer and/or at least one airbag initiator.
In one preferred implementation, the 12-volt, or other voltage, power distribution network also serves as the information network. It can be a time multiplex network, meaning that data sent from one node to another is multiplexed in the time domain rather than the frequency domain. In the extreme case of this network, only a single wire is required with the return, or ground, taking place through the vehicle sheet metal and chassis. All sensors, switches and actuators become active devices on the network. Either special chips or low cost microprocessors are used for the coding and decoding on the data at each device.
Particle Interconnect (PI) may be used to increase the reliability of all connections, switches and relays. PI may also be used to make the connections to the chassis reliable.
Under one preferred design, the network protocol permits critical devices to grab the network when needed. Either coaxial cable or twisted wires, or a combination thereof, are used typically with non-wicking sealant, and if compressed together, provides good inter-strand contact even with sealant. In some cases, particles are added to the sealant to enhance the inter-strand connections when the connectors make connection only to the outermost wires in the bundle. Wicking is when a cut or abrasion occurs in the wire and water wicks through the wire and into various devices. In prior art ball-in-tube sensors used for sensing automobile crashes to deploy airbags, for example, in the early days a significant percentage of the sensors eventually filled with water since there was an air volume trapped in the sensor which acted like a pump as the sensor was heated and cooled by the weather etc. Non-wicking wire, which is wire that contains a sealant, would have prevented this problem. For example, telephone wires that come in from the street to houses are usually coated with a black sealant that prevents water from traveling through the wire bundle.
The benefits to be derived from the vehicle electrical system described herein include at least at 50% cost saving when fully implemented compared with current wire harnesses. A weight savings of at least 50% is also expected. Most importantly, a multi-fold improvement in reliability will result. The assembly into the vehicle is greatly simplified as is the repair in the event that there is a failure in the wiring harness. Most of the connectors are eliminated and the remaining ones are considerably more reliable. Diagnostics on all devices on key-on can now be accomplished over the network with a single connection from the diagnostic circuit. For example, it will now be easy to detect burnt out lights, loose devices, shorts, disconnects, blown fuses, etc. The fusing can be part of each device that makes it easy to identify where the problem is. Therefore, fuses aren't replaced, instead the device or circuit is replaced after the problem is located. In contrast to other multiplexing systems based on zone modules, the communication from and to each device in the instant invention is bi-directional.
It is now believed that for side impacts, the airbag crash sensor should be placed in the door. There is reluctance to do so by the automobile manufacturers since in a crash into the A-pillar of the vehicle, for example, the wires leading to and form the door may be severed before the crash sensor activates. By using the two wire network as described herein, only two, or possibly four if a separate pair is used for power, of wires will pass from the door into the A-pillar instead of the typically fifty or more wires. In this case, the wires can be protected so that they are stronger than the vehicle metal and therefore will not sever during the early stages of the accident and thus the door mounted sensor can now communicate with the airbag in the seat, for example.
In the preferred system then, the power line or distribution network in the vehicle is used to simultaneously carry both power and data to all switches, sensors, lights, motors, actuators and all other electrical and electronic devices (hereinafter call

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