Electrical transmission or interconnection systems – Plural supply circuits or sources – Substitute or emergency source
Reexamination Certificate
1997-12-17
2001-01-23
Paladini, Albert W. (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Substitute or emergency source
C307S044000, C307S066000, C307S009100
Reexamination Certificate
active
06177737
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method and apparatus for remotely backing up a vehicle's volatile memory. The invention more particularly relates to such a method and apparatus that connects to the vehicle's existing electrical system.
Modern vehicles, such as automobiles, employ a number of microprocessor based electrical subsystems, including engine management systems and accessory subsystems such as radio equipment. A common characteristic of these microprocessor based systems and subsystems is that they employ volatile memory, such as RAM, for storing processor generated data, such as engine management data, or user selected data, such as selected radio channels or time of day. Volatile memory is typically selected for these applications because it is durable and, for storing relatively small amounts of data, it is cost effective. Notwithstanding, a notorious drawback of volatile memory in these applications is that, once power is lost, even for a very short time, the memory's contents are also lost. Solutions to this problem so far have not been entirely satisfactory.
For example, Berger, U.S. Pat. No. 5,569,997, proposes a POWER SUPPLY FOR VOLATILE MEMORY DEVICES AND PORTABLE ELECTRICAL APPLIANCE IN VEHICLES employing a rechargeable battery which is isolated from the vehicle's main battery by a diode. The rechargeable battery is at a lower voltage than the main battery and, therefore, must be connected directly to the 5 volt power inputs of the memory circuits in order to provide back-up power. These power inputs, however, are not generally accessible after the circuit has been incorporated in an electrical subsystem and installed in the vehicle. Therefore, such devices cannot be connected simply to automobile electrical devices, such as radio devices, that are adapted to connect directly to a 12 volt power source and are typically installed after-market.
As another example, Kimura, U.S. Pat. No. 5,375,246, proposes a BACK-UP POWER SUPPLY APPARATUS FOR PROTECTION OF STORED DATA having a switch operable between two positions and selecting either a main battery or a back-up battery having a voltage that differs from the main battery voltage by about a diode drop. For 12 volt automobile systems, a back-up battery voltage of about 12 volts would be required. A disadvantage of a requirement for a 12 volt back-up battery voltage is that higher voltage batteries are generally heavier and take up more space than batteries having lower voltages.
Accordingly, there is a need for a vehicle electrical power back-up circuit and method that provides for ease of connection to electrical subsystems designed for after-market incorporation into the vehicle, and that provides for a savings in weight, bulk and cost over the prior art
SUMMARY OF THE INVENTION
The vehicle electrical power back-up circuit and method of the present invention solves the aforementioned problems and meets the aforementioned needs by providing a simple, physically small and cost-effective circuit employing standard integrated circuits and standard low voltage, rechargeable storage batteries.
The electrical power back-up circuit and method employs an auxiliary storage battery and, preferably, a charging circuit for providing or maintaining charge in the storage battery. The charging circuit receives power from the electrical system of the vehicle. The electrical system of the vehicle generally includes a main storage battery, such as a nominal 12V, lead-acid storage battery, and an alternator for charging the main storage battery while the engine is running. The main storage battery is large and heavy for storing sufficient energy to crank the engine of the vehicle.
The auxiliary storage battery is provided to maintain adequate power to volatile memory devices, so that the devices do not lose their memories if the vehicle electrical system fails, even for an instant, to supply power. A relatively small amount of energy is required for this purpose, and the auxiliary storage battery may be relatively light and small.
In the present invention, the auxiliary storage battery is adapted to provide a relatively low voltage, so that a minimum number of standard, low voltage rechargeable battery cells may be employed therein. For example, an exemplary auxiliary storage battery comprises two 1.2 Volt Nickel-Cadmium (“NiCad”) penlight battery cells coupled in series to produce a 2.4 Volt output voltage. By employing an auxiliary storage battery having a relatively low voltage, the present invention provides an auxiliary storage battery that makes most effective use of relatively small energy storage requirements, so that the auxiliary storage battery may be most inexpensively and compactly produced, and so that it may be mounted virtually anywhere in the vehicle.
The invention further provides a voltage booster circuit, coupled to the auxiliary storage battery, to boost the relatively low voltage output of the auxiliary storage battery back to the relatively high voltage of the vehicle electrical system. This provides the additional utility of permitting the vehicle electrical back-up circuit to be connected simply to automobile electrical devices, such as radio devices, which are adapted for direct connection to the higher voltage of the vehicle electrical system and that are typically installed after-market.
Accordingly, it is a principal object of the present invention to provide a novel vehicle electrical power back-up circuit and method.
It is another object of the present invention to provide such a circuit and method that provides for ease of connection to electrical subsystems designed for after-market incorporation into the vehicle.
It is yet another object of the present invention to provide such a circuit and method that provides for a savings in weight, bulk and cost over the prior art.
The foregoing and other objects, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the following drawings.
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patent: 4691118 (1987-09-01), Nishimura
patent: 5375246 (1994-12-01), Kimura et al.
patent: 5569997 (1996-10-01), Berger
patent: 5616968 (1997-04-01), Fujii et al.
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patent: 3-11393 (1991-01-01), None
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Maxim 12V/15V or Adjustable, High-Efficiency, Low IQ, Set-Up DC-DC Converters, Nov. 1997.
Maxim NiCd/NiMH Battery Fast-Charge Controllers, Jan. 1997.
Gress Gary J.
Palfey Paul B.
Paladini Albert W.
Proflow Inc.
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