Fault detection device and transport means or device

The invention relates to an error detection circuit connected to at least one voltage source and at least one Consumer is connectable with at least one sensor, and a vehicle or device.

Conventional vehicles have several solenoids, lamps and Relays on that one via a harness with Vehicle control are connected. An incorrect voltage or incorrect load on a line may have a costly Damage to electrical or electronic components cause and can make inoperable the vehicle.

The US-A-5,017,910 shows a monitoring system with a Plurality of sensors to a central control unit are connected via separate cables. The control unit comprises a microprocessor on which a periodic performs error detection algorithm, while an operator bends each cable in exchange manually. When a Error exhibiting cable is operated, responding Algorithm by actuating a horn.

The problem underlying the invention is seen in that to determine an error, the participation of a Operator is necessary.

This problem is achieved according to the teaching of the claims 1 and 9, respectively, in the other claims the solution advantageously evolving Characteristics are listed.

In this way, a fault detection circuit a relatively simple construction, with simple Components, such as conventional transistors manages. Of the Output transistor can here both as a NPN and as a PNP transistor may be performed, wherein the selection For example, in response to the voltage source or the Consumers who in each case with this conventional transistor Way, for example, connected via lines, carried can. A voltage source having a higher nominal voltage can For example, a PNP transistor can be assigned. Of the Transistor can be in a saturated or in a unsaturated state are.

In a saturated state is between the emitter and Collector only a low voltage on when the transistor is enabled. The transistor is saturated, as it passes through the at its base the voltage applied has been activated, and it not short-circuited or with a consumer with too high Power is connected. In these cases reached the not transistor saturation, making and between emitters Collector an increased voltage appears that by the sensor can be determined. The transistor is used for error detection on the voltage applied to its base voltage is preferably only briefly activated so that a saturation of the transistor may enter, but it no interruption of operation of the consumer or of the load on its associated line comes. Such a circuit may, for example, at a Vehicle can be also used in a working device.

The circuit comprises a microprocessor, then the Sensor to this, an output signal or an output value supply, the microprocessor to process order For example, a warning signal in the form of a visual display or an acoustic signal activated. It can also be provided in that the microprocessor the operation of the Vehicle or work machine partly or completely suppresses, when the sensor detects a high voltage at the Transistor and thus encountered a problem.

The microprocessor may also be at the base of the Output transistor voltage applied to activate or Deactivation of the transistor can be controlled.

The sensor may comprise a fault detection circuit having a have sensor transistor. The sensor transistor is preferably via its collector and emitter with a Voltage source in such a way in conjunction that on the collector a high voltage is applied when the sensor transistor is not is enabled.

If the sensor transistor by the output transistor is activated, the voltage at the collector of the Sensor transistor a lower value, the as can serve fault indicator and, for example, the fed microprocessor or incorporated by and can possibly be further processed.

The base of the output transistor, a preferably light emitting diode, for example in the form of an LED display be connected upstream, which indicates whether at the base of a Activation voltage is applied, so that an operator can quickly determine whether the transistor or at the Using multiple transistors which transistor activated is.

In the circuit, a self-diagnostic resistor or Holding resistor can be provided which ensures that in the Circuit is a voltage when a consumer connected. This resistance is between the switched voltage source and the transistor, so that the Output transistor even without connected consumer can be enabled to determine for example, whether the corresponding line is shorted or the Output transistor itself is not functional.

If a vehicle or a device with such a circuit equipped, so a fault diagnostics during operation of the vehicle or equipment to be carried out without a Operator must intervene at the moment. It is particularly favorable use of vehicles or equipment for lawn, garden and Grounds maintenance, since such devices easy and robust and should be cost-effective.

In the drawing, a detail hereinafter described embodiment of the invention. It shows a schematic representation of a circuit according to the invention or a circuit.

Reference is now made to the sole figure, in which a schematic representation of a portion of a Vehicle circuit or the circuit 10 is shown, the a wiring harness or similar element with a plurality of Lines, indicated generally at 12, and the one Plurality of output lines 12a - 12k, the via connections 13 with various loads or consumers as Solenoids, relays and indicator lamps (not shown) at Vehicle, such for operation of the fuel pump, and for linking actions, such as the presence of a Operator and the operation of the parking brake are include, connected. The lines 12a - 12k are with Output terminals of an amplifier circuit 16 on a Main control board connected. As shown, the Amplifier circuit 16 includes a plurality of power output transistors and output transistors 18a - 18k, one for each the output lines 12a - 12k, on. Detailed Output amplifier circuits are only for the first (18a) and last (18h) output transistor of the amplifier circuit 17 shown, the first power output transistor 18a PNP transistor for switching a high voltage side is to the load or the consumer, as a Kraftstoffpumpensolenoiden or other operation of an engine enabling functions on the line 12a with a Voltage source to be connected to a rated voltage of 12V. The remaining output transistors 18b - 18h (only the Amplifier circuit for 18h is shown, since the amplifier circuits for the transistors 18b - 18g are identical) are NPN transistors to solenoids, relays and indicator lamps 12h to connect with mass - on lines 12b. It should be understood that the number of amplifier circuits 16 and the combination of PNP and NPN output transistors 18 can be varied to different numbers of at Lines 12 and to be adapted to a changing polarity, which are necessary for the loads or consumers, with These lines are connected.

The amplifier circuits 16 have inputs 22a - to 22h with respective outputs of a parallel trap circuit 30 are connected, which in turn by an 8-bit output bus 32 with a conventional chip discharge manifold 34 and a Microprocessor 36 is connected. The microprocessor 36 selects successively various inputs and outputs, including voltage levels, spending Fault detection circuits and switches connection to the Vehicle via a terminal 40 and reads eight of these Inputs and outputs at once a. Control signals are the bus 32 is supplied to the blocking circuit 30, which preselected Output positions in dependence on the signals it from the microprocessor 36 receives, maintains. Everyone who Outputs 22a - 22g selectively provides a basic function voltage for NPN output transistors 18b - 18h a light emitting diode D1, connected to a the base voltages limiting resistor R1 is connected in series to Available. A resistor R2 is connected between the base of each NPN output transistor and ground. The base resistors R1, R2 sure not that stray voltages the transistor burden.

A pull-up resistor or a resistor R3 is connected between a secured power supply (Vbb) and the collector connected, the voltage at the outputs to self-diagnostic purposes pull up or to increase if no external Output lines 12 are connected to the main control board. A buffer diode D2 is connected to the collector of each of the Output transistors 18b - 18h and the voltage source Vbb for connected protection, since many of the loads of the lines 12, so as solenoids and relays are inductively.

A grounded emitter reversing transistor 58 has a base, the R4 a voltage limiting resistor to the Barrier terminal 22a and to ground via the resistor R5 connected is. The collector of transistor 58 is connected via a light emitting diode D3 and a resistor R6 to the base the PNP output transistor 18a, which emitters a which is connected to the voltage source Vs. On Resistor R7 is connected between the voltage source Vs and the base connected, to ensure that the transistor does not by Ghost voltage is charged. A buffer diode D4 is with a resistor R8 in parallel between ground and the collector of the PNP transistor 18a connected. The resistor R8 keeps Output in the line 12a low when the line is not with its load is connected, which, as shown, a Hold solenoid L1 of a fuel pump controller (or a other the function of a drive enabling device) is.

When the lock terminal 22a receives a high voltage, are the transistors 58 and 18 is activated and the diode D3 provides a visual indication that a Kraftstoffsolenoidsignal present and the line 12a is turned on (in the vicinity of the Voltage level of the voltage source Vs). If any of the Terminals 22b - 22h comprises a high voltage, the corresponding to the output transistors 18b - 18h activated the corresponding one of the output lines 12b - 12h to ground. On visual activation signal through the diode D1 for this Output transistor supplied. It can also be an LED display in be the circuit provided that the with the terminals 40 is microprocessor 36, so that a technician can detect a glance which entries are activated, as also that the output lines 12a - 12h in not connected Condition.

An error detection circuit which is shown generally at 70, is connected to the outputs 12b - 12g of the NPN output transistors 18b - 18h each on tension reduction resistors R11 - R17 connected. The circuit 70 includes an NPN transistor sensor 72 grounded with an emitter and a collector output 74 on. The collector is connected through a resistor R18 with a Voltage source Vcc of a nominal voltage of about 5 V connected so that when the sensor transistor 72 is not activated is the output 74 a high voltage (approximately +5 V) will have. The base of the sensor transistor 72 is on the Resistors R11 - R17 to the output lines 12b - 12h connected. If all NPN output transistors 18b - 18h activated and are saturated, the voltage Vce (sat) is the Transistor very low and in the range of 0.1 to 0.2 Volts be such that the voltage at the base of the sensor transistor 72 less than 0.5 V and the base-emitter Activation voltage of the sensor transistor is lying 72nd If some of the output transistors 18b - 18h not activated and some are activated (as is the case when the vehicle is in operation), or when one or more of Output transistors is not saturated, the voltage is applied to the base of the sensor transistor 72 via the Activation voltage rise, thereby causing the Output 74 a low voltage (about 0.1 V) has. A pull-up resistor or holding resistor R19 between the voltage source Vcc and the base of the transistor 72 connected to the circuit 70 sensitive to the State in which an NPN output transistor is not saturated, to make. Since the output transistors 18b - usually 18h are saturated when activated and tidy with the load the lines 12b - 12g are connected, should a short-term switching of all the NPN transistors in the Output circuit 16 cause in the on state, that output 74 having a high voltage (the voltage at the Base of the sensor transistor 72 is below the turn-on fall when all NPN transistors reach saturation), except there is a fault, such as an improper load, a Blown NPN transistor in the circuit 16, a short-circuit to the voltage source in one of the lines 12 in front.

The output 74 of the sensor transistor 72 is connected to the Input circuit 40 of the microprocessor 36, which determines whether the high or low condition at the Output 74 exists. If the condition at the output 74 for the given input to the circuit 16 is wrong, the Microprocessor 36 close all exits and a warning supply, until the problem is corrected. By activating all NPN outputs 12b - 12h except a brief for a Period of time, preferably less than 50 ms for a Resistive load and several hundred milliseconds for a inductive load may, this single output line tested will. The tension in the individual deactivated line should increase in the direction of the supply voltage and cause the voltage at the base of the Sensor transistor 72 via the activation voltage of the Sensor transistor increases, low to Voltage level leads to the output of 74th If the low Level for the particular line which is tested, is detected, the microprocessor 36 in the Flow proceeds to check the next lines of the 12th As However, if at any time any mismatch between the load and the line being tested, is present or when the line is shorted to ground, the Voltage does not rise sufficiently in this line to the Sensor to activate transistor 72 and the microprocessor 36 will provide an error message and close the output. The Test duration is so short that a normal line for each Operation of the vehicle is not impeded during the process, if no errors are found. Therefore, Short circuit fault tests the outputs at regular intervals be carried out during vehicle operation. For example, by testing an output every 50 ms all outputs for shorts in less than a Second are checked. The microprocessor 36 may control the operation immediately end to expensive and time-consuming Component damage prevention.

A circuit 80 is similar to the circuit 70 with the PNP output transistor line 12a. A PNP transistor sensor 82 has an emitter connected to the Voltage source Vs is connected, and a base, which with the line 12a is connected through a resistor R20. The Base is also a pull-up resistor and Holding resistor R21 connected. If the PNP output transistor 18a is turned off, the voltage at the base of PNP transistor sensor 82, whereby the transistor 82 is activated is and the level at the output 84 in the high state arrives. When the transistor 18a is turned on and saturated, what should be the case with normal load, the voltage is in the line 12a in the direction of the voltage of the voltage source Vs rise and cause the sensor transistor 82 is deactivated, which in turn causes the output 84 to a lower level passes. Anyway, when the line 12a inaccurate or incorrect ground with a high-current component is connected (like the tightening coil of the fuel solenoid valve, instead of the lower power need of holding coil) the transistor 18 does not reach saturation, and Voltage of the line will not be sufficient to turn the transistor 82 to disable. The output 84 is high in the state Tension remain. A reducing resistor 22 is connected to the Collector of the transistor 82, to ensure that the output 84 has a low voltage when the Transistor 82 is not activated. A resistor R23 is connected between the collector and the output 84 to the to limit output voltage and the voltage level in to reduce high-voltage state to the to be compatible input constituency of the microprocessor 36, which preferably uses a voltage, which is much lower than the voltage of the voltage source Vs to the Main control board, even at extremely low voltages as in a cold start of the vehicle from a reset hold. The microprocessor 36 checks the condition of the Output 84 and, when the high-voltage state noticed , when the output transistor 18a is activated, a See errors and close the outputs. By Use of a separate circuit 80 for the PNP Output transistor 18a, the sensitivity can against Errors increased and the fuel pump valve L1 or other positive switching, the drive function enabling consumers to be tested more frequently than consumers on the remaining lines 12b - 12h. A Ad diode D6 is connected to the microprocessor 36 and provides a heartbeat-like signal during operation as and a coded signal to provide a visual Indentifikation to supply when a fault is detected.

At a starting of the vehicle, the vehicle circuit is 10 first tested on larger wiring error, so that the Voltage source Vs with one of the lines 12b - 12h connected or the line 12 is grounded or connected to a high current coil instead of being connected to a low power coil L1. All Spending the amplifier circuit 16 are turned off and the Micro Prozesser 36 checks whether a low at the output 74 Value or at the output 84, a high value is present (the Solenoid coils or other wiring on the Lines 12 to the outside or the resistors R3 and R8 burden the transistors 72 and 82 in this position). If those Conditions indicating a fault can not be reached, the error flag is set and the start is aborted. When the initial tests are successful, the NPN outputs 12b - 12h all activated and the output transistors 18 should all be saturated to the sensor transistor 72 to disable and to a high voltage state at the output to provide 74, except when an NPN transistor is blown or the power source Vs inappropriate connected or with a the outputs 12b - is shorted 12h. The PNP transistor output is also activated, which cause should in that the sensor transistor 82 is turned off and at the Output 84, a low value is present, unless the line 12a inappropriate at a high current load as a pulling coil connected or ground. If the previous test no Show error, the microprocessor initiates the normal 36 Launcher of the vehicle. If not, the Error indicator is set, the operation is canceled, and a vehicle operation is inhibited. The microprocessor 36 ignites the particular encoding or encodings that certain, are assigned to determined errors in the light emitting Diode D6.

During operation of the engine, the outputs 12b - 12h all 50 ms tested for connection to ground by only an output line is activated briefly at a time and the low state at the output 74, as previously described, is checked. The outputs 12b - 12h regularly checked in the all NPN output transistors 18b - 18h to on an be activated and briefly examined to determine whether output 74 has a low value. If on the value the output 74 is low, the specific Output line for the transistor is just disabled, possibly shorted to ground. The PNP transistor output 12a is also as set forth above, tested, preferably more frequently than the NPN outputs. When a particular test is not successful, the Error indicator is set and an error code lights up on the Diode D6.

For example only, the following component parameters proposed:<tables><table><tgroup cols="2"><tbody><row><entry align="left">R1, R6</entry><entry align="center">220 Ω</entry></row><row><entry align="left">R2 - R5, R7, R8</entry><entry align="center">10 k</entry></row><row><entry align="left">R11 - R20</entry><entry align="center">10 k</entry></row><row><entry align="left">R21</entry><entry align="center">1.2 kOhm</entry></row><row><entry align="left">R22, R23</entry><entry align="center">10 k</entry></row></tbody></tgroup></table></tables>

Due to the description of the preferred embodiment, it will be apparent that various modifications can be made without departing from the scope of the invention as is determined by the following claims.