Abstract:
A method and system is provided for detecting a charging system fault in a motor vehicle. The motor vehicle includes an existing warning indicator driven by a first signal for indicating when one aspect of the motor vehicle performance is faulty. The method includes detecting a charge system fault, determining if the one aspect of the motor vehicle&#39;s performance is faulty and, if so, driving the existing warning indicator with the first signal. If the one aspect is not faulty and a charge system fault has been detected, the method includes driving the existing warning indicator with a second signal corresponding to the detected charge system fault. The second signal provides a different visual indication than the first signal.

Description:
This application claims the benefit of U.S. Provisional application No. 60/249,042, filed Nov. 14, 2000. 
     The present invention relates generally to electrical circuits. 
    
    
     BACKGROUND 
     Motor vehicles include warning systems for providing audible, visible or other warning indications to a motor vehicle operator of a problem condition related to the performance of the motor vehicle. Often, the warning system include s a display panel that has indicators for signaling of fault conditions. Each indicator traditionally has a single function, warning against a particular condition that has been detected by the warning system. 
     A conventional display panel is limited in size. As a practical matter, the number of faults that can be detected in the complex motor vehicles of today far exceed the amount of space available in a conventional display panel. In some motor vehicles, such as motorcycles, the size of the display panel is severely restricted. Accordingly, conventional warning systems group similar faults creating generalized system level warning indicators (e.g., oil pressure, temperature, battery etc.) Users are alerted to the system level event and respond in accordance with operator instructions. In general, the warning system provides rudimentary information that must be investigated further as to its ultimate cause and correction. While the information is rudimentary, the value is often quite significant. If the motor vehicle operator chooses to disregard the detected fault, permanent damage to the motor vehicle and/or its systems can result. 
     SUMMARY 
     In one aspect, the invention provides a fault detector for determining a charge system fault in a motor vehicle charging system using an existing warning indicator on a display panel of the motor vehicle. The fault detector includes a charge isolator receiving as an input a signal indicative of the charge voltage provided from an alternator of the motor vehicle to the battery, a charge power loss detector operable to determine when a voltage level of the input signal is less than a predetermined threshold, a flasher operable to generate a pulsed signal if the voltage level of the in put signal is less than the predetermined threshold and signaling logic operable to transmit the pulsed signal to an existing warning indicator on a display panel of the motor vehicle, detect a fault associated with the existing warning signal and prioritize between the fault and the charge system fault including selecting a higher priority fault to drive the existing warning indicator. 
     Aspects of the invention can include one or more of the following features. The fault detector can include a flasher timer for controlling a duty cycle of the pulsed signal. The fault detector can include motor vehicle shut-off logic for detecting when the motor vehicle is not operating, and flasher power shut-off logic for shutting down the flasher when the motor vehicle is not operating. The fault detector can include a flasher amplifier operable to receive the pulsed signal and drive the existing warning indictor at a steady rate. The flasher can be an integrated circuit. The fault detector can be a CMOS integrated circuit operating as a monolithic timer in an a stable configuration. The motor vehicle can be a motorcycle, snowmobile, Altra-lite aircraft, or motorboat. The existing warning indicator can be a low oil pressure indicator. The charge isolator can be a rectifier isolation diode. The signaling logic can be operable to transmit the pulsed signal to an existing warning indicator on a display panel of the motor vehicle if a charge system fault is detected and disable the transmission of the pulsed signal to the existing warning signal if the fault associated with the existing warning indicator is detected. The fault associated with the existing warning indicator can be a low oil pressure fault. The oil pressure fault can have a higher priority than a charging system fault. The charger isolator can be operable to isolate the charging system from the motor vehicle&#39;s load and a battery. The charger isolator can be operable to current limit received signals. The existing warning indicator can be selected from the group of a low oil pressure indicator, a high oil temperature indicator, a high water temperature indicator and a low fuel indicator. 
     In another aspect, the invention provides a method for detecting a charging system fault in a motor vehicle. The motor vehicle includes a low oil pressure warning indicator for indicating when oil pressure for the motor vehicle is too low. The method includes detecting a charge system fault, determining if the oil pressure is too low, and if so, driving the low oil pressure warning indicator with a first signal. If the oil pressure is within an acceptable range, and if a charging system fault is detected, the method includes driving the low oil pressure warning indicator with a second signal that is distinct from the first signal used to drive the low oil pressure warning indicator when oil pressure is too low. 
     In another aspect, the invention provides a method for detecting a charging system fault in a motor vehicle. The motor vehicle includes an existing warning indicator driven by a first signal for indicating when one aspect of the motor vehicle performance is faulty. The method includes detecting a charge system fault, determining if the one aspect of the motor vehicle&#39;s performance is faulty and, if so, driving the existing warning indicator with the first signal. If the one aspect is not faulty and a charge system fault has been detected, the method includes driving the existing warning indicator with a second signal corresponding to the detected charge system fault. The second signal provides a different visual indication than the first signal. 
     Aspects of the invention can include one or more of the following advantages. A self-contained, hermetically sealed, alternator-charging system fault detector for any battery charging system is proposed. The battery charging system can be included on a motorcycle snowmobile, motorboat, Altra-lite aircraft and the like. The alternator-charging system utilizes existing vehicle wiring and fault displays. A fault detector uses a single, instrument panel mounted, indicator (e.g., low oil pressure light) for two operational meanings. In a first operational mode, the fault detector operates to detect an alternator low voltage output condition. Upon detecting the alternator low voltage output, the fault detector operates to cause the flashing of the (low oil pressure) indicator. In a second operational mode, when a loss of oil pressure is detected, the oil pressure indicator is illuminated steadily. Both of the fault modes indicate a very serious condition, however, the engine having low oil pressure is generally deemed to be of a more critical nature. A system is provided for prioritizing among the plurality of faults associated with a single fault indicator, and includes a priority indication to distinguish the higher priority fault in the event of a dual system failure. 
    
    
     SUMMARY OF FIGURES 
     FIG. 1 shows a charging system including alternator-charging system fault detector. 
     FIG. 2 shows a schematic block diagram of a fault detector. 
     FIG. 3 shows a detailed electrical schematic for one implementation of a fault detector. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, a charging system  50  that includes an alternator-charging system fault detector (i.e., “fault detector”)  100  is shown. The charging system  50  can be part of a conventional motor vehicle charging system included, for example on a Harley Davidson Motorcycle (not shown). The charging system  50  includes a battery  52 , switch  54 , main circuit breaker  56  and an alternator (portions of which are shown including voltage regulator  60  and stator windings  62 ). Portions of a warning system for the motor vehicle are shown including an oil pressure switch  70  and display panel  72  including oil pressure indicator  74 . 
     Referring now to FIG. 2, a schematic block diagram of the fault detector  100  is shown. Fault detector  100  includes a charger isolator  200 , charger power loss detector  202 , oscillator power filter  206  and flasher (e.g., oscillator)  210 . Associated with power loss detector  202  are a power detector filter  203  and flasher shut off logic  204 . Associated with flasher  210  are power filter  206 , voltage controller  208 , timer  212 , amplifier coupling timer  214 , amplifier  216 , and fault indicator block  218 . 
     Fault detector  100  isolates the charging system  50  from the vehicle&#39;s electrical load  80  and battery  52  through charger isolation  200 . Charger isolation  200  also provides a half wave rectifier filter and current limiter to protect and prevent against alternator or vehicle electrical system damage. 
     Charger power loss detector  202  receives an input from the motor vehicle&#39;s alternator. Charger power loss detector  202  detects a low voltage condition from the output of the alternator (i.e., the alternator output voltage drops below the minimum battery charging level). Upon detection of a low output voltage condition, charger power loss detector  202  powers flasher  210  through flasher power filter  206  and flasher voltage control  208 . Associated with charger power loss detector  202  are one or more power detector filters  203  for filtering the alternator output voltage. In one implementation, the power detector filters  203  are low pass network filters. 
     Flasher power shutoff detector  204  determines the vehicle operating status as to whether the vehicle is running with no charger output (i.e., an alternator fault) or the vehicle is not running (i.e., turned off with no charger output). Flasher power shutoff detector  204  prevents battery discharge through the fault detector  100  by the operation of flasher  210  while the vehicle is not running (i.e., with no alternator output, the normal engine shutoff condition). 
     Flasher  210  can be a CMOS (complementary metal-oxide semiconductor type) integrated circuit (IC) operating as a monolithic timer in an astable configuration. Flasher control timing is controlled by the flasher on/off timer  212 . In one implementation, the flasher on/off timer  212  causes flasher  210  to oscillate at a rate of approximately 2.18 cycles per second. Flasher amplifier coupling timer  214  controls the timing of turning on and off of flasher amplifier  216 . In one implementation, flasher amplifier coupling timer  214  controls the flasher amplifier  216  at a duty cycle of approximately 0.3 seconds on, and 0.15 seconds off. 
     Flasher amplifier  216  provides an output signal to fault indicator block  218 , which in turn provides a fault indication to an indicator on a display panel on the motor vehicle (e.g., the vehicle&#39;s low oil pressure indicator). 
     Operation 
     Fault detector  100  operates on the prioritizing fault principal by alerting the operator of a charging system malfunction. Fault detector  100  detects a charging system failure using a power loss detector  202  and alerts the operator of the motor vehicle (e.g., rider of the motor cycle) that the motor vehicle is operating on limited battery power only. The flashing oil pressure indicator driven by flasher  210  (resulting in a flashing oil pressure indicator on the display panel of the motor vehicle) alerts the operator that the vehicle is operating on limited battery power. The limited battery power warning can provide the motor vehicle operator with sufficient notice to have the motor vehicle serviced without the added inconvenience of a breakdown. For example, with a nominal battery and load, a motorcycle rider can expect as much as 10 hours of motorcycle running, or nearly 600 miles of highway riding after a charge system malfunction has been detected. Results will vary depending on the condition of the battery and the amount of added electrical load on the system. 
     If the engine oil pressure should drop below the manufacture&#39;s preset limit, fault detector  100  will illuminate the low oil pressure indicator steadily (irrespective of a charging system malfunction). The steady illumination of the low-pressure indicator alerts the rider of an engine oil system failure (opposed to flashing, which indicates charging system malfunction). Since the oil system is more important (or a higher priority) than battery charging, fault detector  100  prioritizes the faults and provides an indication of the higher priority system failure. If at any time the oil pressure should come back within limits, then fault detector  100  will provide a charging system failure indication (with a flashing low oil pressure light) again. 
     Referring now to FIGS. 2 and 3, a more detailed view of one implementation of fault detector  100  is shown. In the implementation shown, fault detector  100  includes a plurality of components including a pair of transistors (Q 2  and Q 3 ), a pair of diodes (D 1  and D 2 ), six capacitors (C 1 -C 6 ), five resistors (R 1 -R 5 ) and an integrated circuit (IC). 
     Fault detector  100  isolates the charging system  50  from the vehicle&#39;s battery  52  and electrical load  80  through a rectifier and isolation diode  102  (D 1 ). In one implementation, rectifier and isolation diode  102  (D 1 ) is a 32-ampere rectifier and isolation diode. A first terminal (A 1 - 2 ) of rectifier and isolation diode  102  is coupled to the output of the voltage regulator  60 . A second terminal (A 1 - 1 ) of rectifier and isolation diode  102  is coupled with to one terminal of the main circuit breaker  56 , the second terminal of which is coupled to battery  52 . Rectifier and isolation diode  102  provides charger system isolation and is used as a half wave rectifier filter and current limiter to protect and prevent against alternator or vehicle electrical system damage. 
     Integrated circuit (IC)  126  is a flasher circuit that includes a plurality of inputs. The integrated circuit can be a CMOS (complementary metal-oxide semiconductor) type device operating as a monolithic timer in an astable configuration. 
     First terminal A 1 - 2  of rectifier and isolation diode  102  is coupled to the base of a transistor  104  (Q 2 ), a first terminal of first capacitor  106  (C 5 ), a first terminal of a second capacitor  108  (C 6 ) and first terminal of a first resistor  110  (R 4 ). The collector of transistor  104  (Q 2 ) is coupled to a second terminal of first resistor  110  (R 4 ). The emitter of transistor  104  (Q 2 ) is coupled to a first terminal of diode  112  (D 2 ) and to the first terminal of a third capacitor  114  (C 4 ). The second terminal of the second diode  112  (D 2 ) is coupled to the collector of a second transistor  124  (Q 3 ) and to the low oil pressure indicator  74  via a signaling port  150  of fault detector  100 . The collector of the first transistor  104  (Q 2 ) is also coupled to the first terminal of a fourth capacitor  116  (C 3 ) and the first terminal of a second resistor  122  (R 3 ). The base of second transistor  124  (Q 3 ) is coupled to a first terminal of a third resistor  128  (R 5 ), the first terminal of a fifth capacitor  118  (C 2 ) and the third input to integrated circuit  126 . 
     The second terminals of the second and third resistors  122  and  128  (R 3  and R 5 ) are coupled to the fourth input of integrated circuit  126 . A first terminal of each of a fourth and fifth resistor  130  and  132  (R 1  and R 2 ) are coupled to the seventh input of integrated circuit  126 . The second input to the integrated circuit  126  is coupled to the first terminal of sixth capacitor  120  (C 1 ), the sixth input to the integrated circuit  126  and a second terminal of fourth resistor  130  (R 1 ). The second terminal of fifth resistor  132  (R 2 ) is coupled to the eighth input of integrated circuit  126 . 
     The second terminal of third capacitor  114  (C 4 ), the first terminal of fourth and fifth capacitors  116  and  118  (C 3  and C 2 ), the second terminals of first and second capacitors  106  and  108  (C 5  and C 6 ), the second terminal of sixth capacitor  120  (C 1 ), the emitter of second transistor  124  (Q 3 ) and the first input to integrated circuit  126  are all coupled via a ground port  140  to ground. 
     Operation 
     When the alternator output voltage drops below the minimum battery charging level, tap A 1 - 2 , on the anode side of diode D 1  (first diode  102 ) goes low driving the base side of transistor Q 2  (first transistor  104 ) into the forward bias state, allowing current flow from the battery  52 , through the vehicle&#39;s ignition switch (i.e., switch  54 ), the low oil pressure indicator  74  and diode D 2  (second diode  112 ), to turn on the power loss detector Q 2  (first transistor  104 ). 
     The power loss detector transistor Q 2  (first transistor  104 ), being forward biased in a common emitter circuit by resistor R 4  (first resistor  110 ), supplies system operating voltage to the flasher (IC  126 ). Diode D 2  (second diode  112 ), the flasher power shutoff detector, determines the vehicle operating status as to whether it is running with no charger output (i.e., an alternator fault), or not running (i.e., turned off, with no charger output) to prevent battery discharge through fault detector  100  from the flasher (IC  126 ) operating while the motor vehicle is not running (i.e., with no alternator output, the normal engine shutoff condition). 
     Filtering of the alternator output voltage for transistor Q 2  (first transistor  104 ) is provided by capacitors C 5 , C 6  (first capacitor  106 , and second capacitor  108 ) in the form of a low pass network filter. Flasher supply voltage is controlled and filtered through the oscillator power filters C 3 , C 4  (fourth capacitor  116  and third capacitor  114 ), and the flasher voltage controllers R 3 , R 5  (second resistor  122  and third resistor  128 ). 
     Flasher control timing is provided by the flasher on/off timing circuit R 1 , R 2 , C 1  (fourth resistor  130 , fifth resistor  132  and sixth capacitor  120 ). In one implementation, the flasher on/off timer controls the flasher (IC  126 ) at a rate of approximately 2.18 cycles per second, and controls the flasher amplifier Q 3  (second transistor  124 ) at a duty cycle of approximately 0.3 seconds on, and 0.15 seconds off. 
     The output of the flasher (IC  126 ) is connected to the base of the flasher amplifier Q 3  (second transistor  124 ) through a coupling timer capacitor C 2  (fifth capacitor  118 ) that keeps the flashing rate steady. 
     A number of embodiments of the invention have been described. Nevertheless, it may be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.