JP5627545B2 - Power supply monitoring system for on-board equipment - Google Patents

Description

  The present invention appropriately determines whether or not the current device is operating at an appropriate voltage due to the influence of the voltage fluctuation caused by the battery voltage fluctuation or the load fluctuation of the equipment itself. The present invention relates to a power supply monitoring system for on-vehicle equipment that can be monitored.

  The vehicle is equipped with various devices such as a head unit, a navigation device, a disk changer, especially a speaker system and a power amplifier that are mounted to enhance the sound effect, and the vehicle engine is charged by driving the generator. It can be operated using a battery power source.

  In addition to the on-vehicle equipment as described above, such a vehicle battery drives various vehicle auxiliary equipment such as headlamps and other lighting equipment, defrosting electric heaters, wipers, and air conditioner auxiliary equipment. Is also used as its power source. For this reason, depending on the operating state of these vehicle auxiliary devices, the voltage of a battery that is charged in advance so as to be maintained at a predetermined voltage such as 12 V, for example, temporarily decreases, or the voltage decreases for a relatively long time. May continue.

  Therefore, for various vehicle-mounted devices such as the head unit, navigation device, and power amplifier as described above, for example, when the devices are activated, there is a risk that each device may malfunction if the battery voltage is lower than a predetermined value. For this reason, monitoring is performed so as not to start up, or even when these devices are in operation, the risk of malfunctioning increases when the battery voltage drops below a predetermined level.

  At that time, for example, as shown in FIG. 4A showing the conventional example (1), a vehicle battery 31 and a vehicle-mounted device 32 such as an audio device are connected, and the device shown as the vehicle-mounted device operating section 34 is connected. When the operating unit performs a predetermined operation, it is predicted that the vehicle-mounted device operating unit 34 cannot perform the predetermined operation at a voltage required for the vehicle-mounted device 32 to perform the predetermined operation, that is, lower than that. A vehicle-mounted device operating voltage monitoring unit 33 that monitors whether or not the voltage is present is provided for monitoring. In many cases, the vehicle-mounted device operating voltage monitoring unit 33 is incorporated in the microcomputer of the control unit of each vehicle-mounted device.

  In the example of the vehicle-mounted device operating voltage monitoring unit 33 shown in the figure, the battery voltage detection unit 35 sequentially detects the voltage (Vbatt) supplied from the vehicle battery 31 to the vehicle-mounted device 32 and uses the detected value as the device. This is output to the operating voltage abnormality determination unit 38. Therefore, here, when the battery 31 is originally set to maintain a voltage of 12 V, depending on the load of various devices that use the battery 31 as a power source and the balance of the generator driving capability of the engine with respect to the battery 31, for example, When the voltage is lowered to 9V, the battery voltage detection unit 35 detects that Vbatt is 9V and outputs it to the device operating voltage abnormality determination unit 38. At this time, the battery voltage detection unit 35 inputs the A / D converter to the microcomputer that functions as the on-vehicle equipment operating voltage monitoring unit 33 as described above, and performs predetermined data processing as a digital signal. It can be performed.

  On the other hand, the vehicle-mounted device operating voltage monitoring unit 33 includes a battery reference voltage setting unit 36, and a voltage value (Vbatt ( s)) is set. Therefore, when the battery 31 is originally set to maintain 12V, the vehicle-mounted device 32 is designed to operate by being supplied with a voltage of 12V. In this case, the battery reference voltage setting unit 36 Then, it is set in advance as Vbatt (s) = 12V.

  The battery voltage corresponding voltage fluctuation allowable range setting unit 37 is necessary for various vehicle-mounted devices 32 to properly operate with respect to the battery reference voltage such as 12 V as described above in the battery reference voltage setting unit 36. The allowable range of voltage fluctuation is set. The example shown in FIG. 4 shows an example in which an allowable range of ± a is set with respect to the battery reference voltage (Vbatt (s)) as a range in which this vehicle-mounted device operates properly. In this example, the upper limit Vbatt (max) of the allowable voltage fluctuation range corresponding to the battery voltage is set to [Vbatt (s) + a] and the lower limit Vbatt (min) is set to [Vbatt (s) −a].

  In the device operating voltage abnormality determination unit 38, the current battery voltage Vbatt from the battery voltage detection unit 35 as described above, the upper limit value Vbatt (max) and the lower limit value Vbatt ( the battery voltage Vbatt is between the upper limit value Vbatt (max) and the lower limit value Vbatt (min), that is, Vbatt (min) <Vbatt <Vbatt (max) is normal It is determined whether it is within a range.

  As shown in FIG. 4B, the determination at this time is centered on a reference voltage Vbatt (s) which is a fixed value such as 12 V, and is a voltage width as a fixed value set in advance, for example, ± 2 V or the like. ± a is set, and when the measured battery voltage Vbatt is within this range, it is determined as “normal”, when it is determined that it is out of range, that is, when Vbatt ≦ Vbatt (min), and When Vbatt ≧ Vbatt (max), it is determined as “abnormal”.

  Therefore, when the battery reference voltage Vbatt (s) of the battery 31 is, for example, 12V, and the battery voltage corresponding voltage fluctuation allowable range ± a is ± 2V, the upper limit Vbatt (max) is Vbatt (s) + a 12V + 2V = 14V and the lower limit Vbatt (min) is Vbatt (s) -a 12V-2V = 10V.

  As a result, when the battery voltage Vbatt currently supplied to the vehicle-mounted device 32 by the battery voltage detection unit 35 is 9 V, the operation voltage of the vehicle-mounted device 32 is “abnormal” in the device operating voltage abnormality determination unit 38. It is determined that the proper operation cannot be performed. As a result, the device operating voltage abnormality output unit 39 outputs such that, for example, when the vehicle-mounted device 32 is just turned on, it does not start to prevent the device from malfunctioning, and the vehicle-mounted device 32 is operating properly. When an abnormal output as described above is made, an output for immediately stopping the operation of the on-vehicle equipment 32 is performed. At that time, if necessary, a message such as “battery voltage drop” is displayed to inform the user.

  As a method for monitoring the operating voltage in the conventional vehicle-mounted device, as described above, the battery voltage supplied from the vehicle battery to the vehicle-mounted device as shown in FIG. For example, as shown in FIG. 5 as a conventional example (2), for example, the output voltage (Vo) of the power supply circuit 44 of the on-vehicle equipment 42 is monitored, and this voltage value falls within a predetermined range. It is also monitored whether or not.

  That is, in the conventional example shown in FIG. 5, when the vehicle-mounted device 42 such as an audio device is provided with a power supply circuit 44 that performs operations such as boosting the voltage (Vbatt) taken from the battery 41, the vehicle-mounted device 42. In this example, whether or not is operating at an appropriate output voltage is determined by monitoring the output voltage (Vo) of the power supply circuit.

  Therefore, in the example shown in FIG. 5, the internal power supply circuit output voltage detection unit 46 of the vehicle mounted device operating voltage monitoring unit 43 takes in the output voltage (Vo) of the power supply circuit 44 of the vehicle mounted device 42 to determine whether the device operating voltage is abnormal. To the unit 49. The internal power supply circuit output reference voltage setting unit 47 sets a reference voltage (Vo (s)) corresponding to the output voltage of the power supply circuit specific to each device, and the voltage fluctuation allowable range corresponding to the internal power supply circuit voltage. The setting unit 47 sets an upper limit and a lower limit as an allowable range of ± b for the reference voltage value.

  In the example shown in FIG. 5, the upper limit voltage Vo (max) is set to Vo (s) + b by adding b, which is a predetermined allowable range voltage, to the reference voltage Vo (s). The voltage Vo (min) is obtained by subtracting b, which is a voltage within a predetermined allowable range set in advance, from the reference voltage Vo (s) to obtain Vo (s) −b.

  In the device operating voltage abnormality determination unit 49, the output voltage of the current power supply circuit detected by the internal power supply circuit output voltage detection unit 46 as described above is the upper limit value set by the internal power supply circuit voltage corresponding voltage allowable range setting unit 48. It is determined whether it exists within the lower limit. Therefore, as shown in the figure, it is determined whether or not Vo (min) <Vo <Vo (max), and if it is within the range, it is determined that it is in the normal range. This determination method is shown in FIG. Further, when it is outside this range, the output voltage of the internal power supply circuit of the vehicle-mounted device is determined as “abnormal” because there is a strong possibility that the device does not operate properly, and the device operating voltage abnormality output unit 50 4 is output.

  As for the conventional power supply voltage monitoring technology for vehicle-mounted devices, there are a method for directly detecting and monitoring the battery voltage of the vehicle as described above, and a method for monitoring the output voltage of the power supply circuit included in each vehicle-mounted device. In addition, in order to monitor the power supply voltage more accurately, both methods are also used together, thereby monitoring the influence of the battery voltage of the on-vehicle equipment, and further the voltage of the power circuit inside the on-vehicle equipment, The vehicle-mounted device can be operated safely and reliably when the voltage is abnormal.

  In addition, in a power supply device that can be operated with multiple power sources with different voltages, manual setting of the detection level of the power supply voltage is unnecessary, and a voltage detection signal corresponding to the power supply voltage supplied to the power supply device is automatically generated. In order to obtain the voltage detection unit for low voltage for 100V and the voltage detection unit for high voltage for 200V, each voltage detection unit is supplied with a voltage of 80% or more of the nominal voltage, for example, For example, a voltage detection signal having a pulse width corresponding to a period exceeding 80% of the nominal voltage is output. When the high voltage detection signal is supplied to the voltage detection signal selection switching circuit, the high voltage detection signal is input. Patent Document 1 discloses a technique for outputting a low voltage detection signal as an input voltage detection signal when it is output as a voltage detection signal and no high voltage detection signal is supplied. It has been.

Japanese Patent Laid-Open No. 11-202005

  In recent vehicles, energy saving is particularly advanced, and the fuel efficiency of the vehicle is improved by various methods. One of the countermeasures is idling to reduce fuel consumption due to idling of the engine when the vehicle running in the city often stops for a long time with a large number of signals and is waiting for a signal. An increasing number of vehicles adopt an engine control method called idling stop, in which the engine is stopped as much as possible and the engine is started when the accelerator is depressed.

  When such an idling stop method is used, the engine is frequently stopped particularly when traveling in the city, and at that time, the charging time for the battery mounted on the vehicle is greatly reduced. Therefore, the battery of a vehicle that performs such idling stop has a voltage lower than that of a conventional vehicle battery, and it often increases for a long time.

  Therefore, such a device mounted on a vehicle is required to have a function of reliably operating even at a lower voltage than in the past, and in particular, since there is a high possibility that the battery voltage will decrease, it is ensured when the battery drops more than a predetermined level. It is required to stop the operation of equipment and prevent malfunctions.

  For this reason, in-vehicle devices are often provided with a boosting power source using a transformer in the power supply circuit so that the device can be reliably operated even at a low power supply voltage. In particular, audio devices are required to have high sound quality and volume, and are often equipped with high-output woofers that can reliably output low frequencies. For this reason, audio devices are equipped with a transformer for boosting the power supply circuit. Equipped with high voltage and high power operation. Also, in other vehicle-mounted devices, in order to ensure more reliable device operation, the power supply circuit output is often boosted using a transformer in the power supply circuit.

  As described above, when a step-up transformer is used in the power supply circuit, the signal in the operation of the on-vehicle equipment is also boosted in proportion. As a result, in the DC-DC converter, the upper limit value of the output voltage is determined by the winding ratio of the transformer and the battery voltage. For example, when the battery voltage decreases, the output voltage tends to decrease greatly.

  In view of this, in order to avoid a significant decrease in the output voltage of the power supply circuit of each on-vehicle device due to a decrease in the battery voltage, it is necessary to increase the winding ratio of the transformer of the power supply circuit. However, if the winding ratio of the transformer is simply increased, the duty ratio of the signal at the time of device operation is lowered at the battery voltage during normal operation, and the efficiency of the power supply is deteriorated.

  If the turns ratio of the transformer is not changed, the output voltage of the power supply circuit of the device will drop when the battery voltage drops, and the output voltage will be reduced to a voltage that is abnormal in the voltage detection setting in the normal state. As described above, the number of cases where it decreases is increased. On the other hand, when the battery voltage is rising, it is detected that the voltage is abnormal even when a load higher than expected is applied in the operation of the on-board equipment, or even if the voltage drops more than a predetermined level. There is a problem in that it does not fall to a possible level and may be judged as normal.

For example, when the battery voltage is 14.4V and the transformer winding ratio is 3 times, the output voltage is 43.2V.
If the transformer winding ratio is 3 times when the battery voltage is 7.0V, the output voltage is 21.0V.
However, in this case, if the output voltage is expected to decrease due to load fluctuation, and if it is set to output that the voltage is “abnormal” when it is detected that the output voltage has decreased to 18 V, the load will be detected when 14.4 V is detected. Even if the voltage drops to half of 7.2 V due to an abnormality in the device, it cannot be detected as an “abnormal” state, and the operation of the device cannot be stopped.

  4 and FIG. 5, in the conventional technique shown in FIG. 4 and FIG. 5, even if both techniques are used together, the technique of the conventional example (1) in FIG. In the technique (2), only the output of the power supply circuit of the vehicle-mounted device is monitored, and since each monitoring is independent and unrelated, the above problem cannot be solved.

  Therefore, the present invention is based on functions such as load fluctuation of various devices of battery voltage and idling stop in a vehicle-mounted device that uses a power source of a vehicle battery and operates by using a transformer in a power circuit of each device. Even when a large voltage fluctuation and a large load fluctuation of the on-vehicle equipment itself are superimposed, the abnormal operation due to the voltage fluctuation of the on-vehicle equipment is reliably detected, and the operation of the on-vehicle equipment is surely performed when an abnormality is detected. The main purpose is to obtain a vehicle-mounted equipment power supply monitoring system that can be stopped.

  In order to solve the above problems, a power monitoring system for a vehicle-mounted device according to the present invention includes a battery voltage detection unit that detects a voltage of a vehicle battery, and the battery in a vehicle-mounted device that operates using the battery as a power source. Device power transformer winding ratio acquisition means for acquiring the winding ratio of the transformer in the equipment power supply circuit that boosts the voltage of the transformer by the transformer, the battery voltage detected by the battery voltage detection means, and the device power transformer transformer winding ratio acquisition means The device power boost voltage detecting means for detecting the power boost voltage of the on-vehicle equipment based on the winding ratio acquired in step (b), and a predetermined allowable width above and below the device power boost voltage detected by the device power boost voltage detecting means, Voltage fluctuation allowable rate setting means set as a ratio to the device power supply boost voltage, and voltage fluctuation allowable rate set by the voltage fluctuation allowable rate setting means A voltage fluctuation allowable range calculating means for calculating an upper limit value higher than the device power supply boosted voltage and a lower limit value lower than the device power supply boosted voltage, and a device operating voltage detecting means for detecting an operating voltage of the vehicle-mounted device. The device operating voltage abnormality determining means for determining whether or not the current device operating voltage of the vehicle-mounted device detected by the device operating voltage detecting means is within an allowable range calculated by the voltage fluctuation allowable range calculating means; When the device operating voltage abnormality determining means detects that the current operating voltage of the on-vehicle device is not within the allowable range, it determines that the device operating voltage is abnormal, and outputs a signal indicating that the device operating voltage is abnormal. And a determination output means.

  In another power monitoring system for on-vehicle equipment according to the present invention, in the power monitoring system for on-vehicle equipment, the voltage fluctuation allowable rate setting means sets the voltage fluctuation allowable rate to a preset fixed ratio. It is characterized by that.

  Another vehicle-mounted equipment power supply monitoring system according to the present invention is characterized in that, in the vehicle-mounted equipment power supply monitoring system, the voltage fluctuation allowable rate setting means sets the voltage fluctuation allowable rate to a ratio that is arbitrarily changed. And

  Another vehicle-mounted equipment power supply monitoring system according to the present invention is characterized in that, in the vehicle-mounted equipment power supply monitoring system, the changed ratio is set to a ratio corresponding to a load change with respect to the power supply.

  Another vehicle-mounted equipment power supply monitoring system according to the present invention is characterized in that, in the vehicle-mounted equipment power supply monitoring system, the changed ratio is set to a ratio corresponding to a change in a surrounding environment of the vehicle-mounted equipment. To do.

Another power supply monitoring system for on-vehicle equipment according to the present invention is characterized in that, in the power monitoring system for on-vehicle equipment, the changed ratio varies depending on an instruction to the vehicle or a signal of an instruction to the on-vehicle equipment. To do.
It is characterized by that.

  Since the present invention is configured as described above, in a vehicle-mounted device that operates using a power source of a vehicle battery and boosts the power supply circuit of each device using a transformer, Even when large voltage fluctuations due to functions such as idling stop and large load fluctuations of the on-board equipment itself are superimposed, abnormal operation due to voltage fluctuations on the on-board equipment can be reliably detected. It is possible to reliably stop the operation of the on-vehicle device, and to prevent the start-up itself from being performed when the device is started.

It is a functional block diagram of the Example of this invention. It is an operation | movement flowchart of the Example. It is a figure which shows the function by the Example. It is a figure which shows a prior art example. It is a figure which shows another prior art example.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram illustrating a voltage monitoring system for on-vehicle equipment according to the present invention that can be implemented in various modes. Therefore, in this invention, it can implement in a various aspect by selecting suitably each function part shown in FIG. In addition, the function part which performs each function in the figure can also be said to be a means which performs each function.

  The vehicle battery 1 shown in FIG. 1 is charged so that a predetermined voltage can be maintained in principle by a generator driven by an engine, as in the prior art. However, as described in the prior art, since this battery is commonly used by various devices mounted on the vehicle, charging is not in time due to the operating load of those devices, or voltage adjustment is not always performed properly. There are also times when there is no such thing, and in recent years, many vehicles have adopted it, so when performing idling stop function to stop the engine when idling such as waiting for a signal, charging the battery due to frequent idling stop The voltage of the battery 1 may change greatly due to insufficient operation.

  There are various types of on-vehicle equipment 2 shown in FIG. 1, but an audio device that requires high output often requires a high voltage. For example, a battery power supply that is set to be 12V The device power supply circuit 4 is configured to be boosted by a transformer. In the example of the device power supply circuit 4 shown in the figure, an example in which the winding ratio of the transformer is [1: 3], that is, the winding ratio (n) is 3, is shown.

  In the vehicle-mounted device 2, the power source of the device power supply circuit 4 is used to operate the vehicle-mounted device operating unit 7 as an operating unit such as a head unit or an amplifier in the audio device, for example. The vehicle-mounted device 2 shown in FIG. 1 includes an input signal detection unit 5 that detects an input signal corresponding to an audio signal when the vehicle-mounted device operating unit 7 is an audio device, for example. The voltage fluctuation allowable rate setting unit 11 of the device operating voltage monitoring unit 3 can be used when setting the voltage fluctuation allowable rate (α).

  Further, the vehicle-mounted device 2 shown in FIG. 1 includes a vehicle-mounted device load instruction detection unit 6 that detects, for example, a volume instruction in which the user arbitrarily indicates the volume, and this detection signal will also be described later. When the voltage fluctuation allowable rate (α) is set by the voltage fluctuation allowable rate setting unit 11 of the vehicle-mounted equipment operating voltage monitoring unit 3, it is usable.

  The vehicle-mounted device operating voltage monitoring unit 3 monitors whether or not the vehicle-mounted device 2 is within a voltage range in which the vehicle-mounted device 2 operates properly, similarly to the conventional device shown in FIGS. 4 and 5. In the present invention, this part is greatly different from that of the prior art. That is, the vehicle-mounted device operating voltage monitoring unit 3 shown in FIG. 1 includes a device power transformer transformer winding ratio acquisition unit 8 to acquire the winding ratio (n) of the transformer included in the power circuit 4 of the vehicle mounted device 2. This is output to the device power supply boost voltage detection unit 10. This winding ratio (n) is inherently designed at the time of production of each on-vehicle equipment, but it is possible to change the winding ratio by selecting and changing the lead wire from the transformer according to the operation of the on-vehicle equipment. It may have a function of changing the ratio (n).

  The battery voltage detection unit 9 detects the battery voltage (Vbatt) supplied from the battery 1 to the device power supply circuit 4 of the on-vehicle device 2 and outputs it to the device power supply boost voltage detection unit 10. The device power supply boost voltage detection unit 10 is mounted on the vehicle based on the transformer winding ratio (n) from the device power supply transformer winding ratio acquisition unit 8 and the battery voltage (Vbatt) from the battery voltage detection unit 9 as described above. The current device power supply boosted voltage (Vo (typ)) supplied from the device power supply circuit 4 of the device 2 to the on-vehicle device operating unit 7 is detected.

  The voltage variation allowable rate setting unit 11 shown in FIG. 1 sets an allowable power supply voltage variation allowable rate (α) when the vehicle-mounted device 2 is properly operated. α) may be a fixed value set by the fixed value setting unit 12, for example, 20%, or may be set by the fluctuation value setting unit 13 in consideration of various states as will be described later. good. Furthermore, if necessary, a fixed value can be adopted in a predetermined operating state, and a variation value can be set in other states.

  In the illustrated voltage fluctuation allowable rate setting unit 11, an example in which a load fluctuation detection unit 14 is provided in order to change the voltage fluctuation allowable rate corresponding to various operating states is shown. In the load fluctuation detection unit 14, when the vehicle-mounted device 2 is an audio device, for example, the audio device outputs a particularly large output such as detecting the volume of a signal output by the input signal detection unit 5, particularly the volume of a bass portion. A necessary state is detected, the signal is input by the load fluctuation detection unit 14 and is output to the fluctuation value setting unit 13.

  In addition, in the load fluctuation detection unit 14, for example, a direct instruction that the user fluctuates the load of the audio device, such as a volume instruction as described above, in the on-vehicle equipment load instruction detection unit 6 of the on-vehicle equipment 2. May be detected by the load fluctuation detection unit 14 and output to the fluctuation value setting unit 13.

  The voltage variation allowable rate setting unit 11 shown in FIG. 1 includes a surrounding environment detection unit 15 that detects the temperature of the operating environment of the vehicle-mounted device 2 with a thermometer (not shown) and is in a high temperature state, for example, higher than a predetermined level. The operating environment of the device is detected, and the signal is output to the fluctuation value setting unit 13. As the surrounding environment to be detected here, various surrounding environments are detected such as detecting the environment and operating state of the vehicle electrical component through communication etc. in addition to the temperature as described above, and detecting the operating environment of the peripheral device. can do.

  The operation instruction detection unit 16 detects an instruction from the user or an automatic instruction signal or the like under a predetermined condition set in advance, and outputs it to the fluctuation value setting unit 13. As instructions at this time, there may be, for example, an instruction to adjust low-frequency output in an audio device, an instruction to operate a high-load device such as an air conditioner, and an instruction to operate an idling stop function that causes a particularly low battery voltage. Therefore, in the fluctuation value setting unit 13 in the voltage fluctuation allowable rate setting unit 11, an appropriate voltage fluctuation allowable rate can be set corresponding to the various states as described above.

  In the voltage fluctuation allowable range calculation unit 18, the device power supply boosted voltage (Vo (typ)) obtained by the device power supply boosted voltage detection unit 10 and the voltage fluctuation allowable rate (α) set by the voltage fluctuation allowable rate setting unit 11. ) To calculate an upper limit value and a lower limit value in which voltage fluctuation is allowed. In this case, as shown in the figure, the upper limit Vo (max) is obtained by Vo (typ) × (1 + α), and the lower limit Vo (min) is obtained by Vo (typ) × (1−α). .

  The voltage fluctuation allowable range calculated by the voltage fluctuation allowable range calculation unit 18 is obtained by the above-described method, and particularly corresponds to the current state of the battery voltage and in the power supply circuit of the vehicle-mounted device. The output value of the device operating power supply taking into account the transformer winding ratio is surely handled, and an appropriate allowable range based on the output value is set.

  In the device operating voltage abnormality determination unit 19, the voltage operated by the vehicle mounted device operating unit 7 in the current vehicle mounted device 2 within the voltage variation allowable range calculated by the voltage variation allowable range calculating unit 18 as described above. It is determined whether or not the device operating voltage Vo detected by the device operating voltage detection unit 17 is included. As shown in the figure, when Vo (min) <Vo <Vo (max), it is assumed that it is in the normal range, and conversely, when it is not within that range, it is determined that the current operating voltage of the on-vehicle equipment is abnormal. In this case, the signal is output to the device operating voltage abnormality determination output unit 20.

  When the abnormality determination result is output, the device operating voltage abnormality determination output unit 20 is configured not to start when the vehicle-mounted device 2 is about to start, and to stop the device while the device is operating. Output. In that case, the display part of each apparatus may display appropriately that the apparatus is not started or the operation is stopped because the operating voltage is in an abnormal range.

  In the present invention comprising the functional blocks shown in FIG. 1, the present invention can be implemented by the operation flow shown in FIG. 2, for example. In the example of the vehicle-mounted equipment operating voltage monitoring process shown in FIG. 2, first, the vehicle battery voltage (Vbatt) is detected (step S1). This operation is performed by the battery voltage detector 9 of FIG.

  Next, the on-vehicle equipment power transformer winding ratio (n) is acquired (step S2). This operation is performed by the device power transformer transformer winding ratio acquisition unit 8 of FIG. 1, but in many cases, it is a unique value of the vehicle-mounted device 2 itself as described above. Thereafter, the vehicle equipment power supply boost voltage (Vo (typ)) is calculated (step S3). This calculation is performed by Vo (typ) = Vbatt × n as shown in the apparatus power supply boost voltage detection unit 10 of FIG.

Therefore, if the transformer turns ratio is primary: secondary = 1: 3, n = 3,
When Vbatt = 16.0V Transformer output voltage Vo (typ) = 16.0 × 3 = 48V
When Vbatt = 14.4V Transformer output voltage Vo (typ) = 14.4 × 3 = 43.2V
When Vbatt = 12.0V Transformer output voltage Vo (typ) = 12.0 × 3 = 36V
When Vbatt = 10.0V, transformer output voltage Vo (typ) = 10.0 × 3 = 30V
When Vbatt = 8.0V Transformer output voltage Vo (typ) = 8.0 × 3 = 24V
When Vbatt = 6.0V Transformer output voltage Vo (typ) = 6.0 × 3 = 18V
As a result, the vehicle equipment power supply boost voltage Vo (typ) is obtained.

  Thereafter, the voltage fluctuation allowable rate (α) is set (step S4). For this setting, the voltage fluctuation allowable rate setting unit 11 in FIG. 1 adopts a fixed value such as 20% preset in the fixed value setting unit 12 as described above, or further, the fluctuation value setting unit 13 loads the load fluctuation. This can be done by varying and setting the voltage fluctuation allowable rate (α) as described above according to signals from the detection unit 14, the surrounding environment detection unit 15, the operation instruction detection unit 16, and the like.

  Next, a voltage fluctuation allowable range is calculated (step S5). This calculation is performed by calculating Vo (typ) × (1 + α) for the upper limit Vo (max) and the lower limit Vo (min) as described above in the voltage fluctuation allowable range calculation unit 18 of FIG. This is done by calculating Vo (typ) × (1−α). Thus, when the allowable rate (α) is 20%, when the battery voltage (Vbatt) is 12.0V, the transformer output voltage Vo (typ) = 12.0V × 3 = 36V, and the lower limit value Vo (min ) = Vo (typ) × (1−α) = 28.8V, and the upper limit value Vo (max) = Vo (typ) × (1 + α) = 43.2V.

  As described above, on the basis of the on-vehicle equipment power supply boost voltage that corresponds to the fluctuation of the power supply voltage and fluctuates depending on the winding ratio of the transformer, the fluctuation rate is set for the value, and the upper limit value and the lower limit value are set. Since it is set, the maximum and minimum values will vary depending on load fluctuations, component variations, and the impedance of the elements that make up the power supply circuit, and an appropriate allowable range is set according to the characteristics of each on-vehicle device. It becomes possible.

  It should be noted that when setting the allowable range, the permissible range originally changes from moment to moment according to changes in battery voltage and the like. For this reason, the battery voltage may be updated as soon as it is detected, but the allowable range may be updated by detecting the battery voltage at regular time intervals.

  Thereafter, the current device operating voltage (Vo) is detected (step S6), and it is determined whether or not the device operating voltage (Vo) is within the voltage fluctuation allowable range (step S7). This operation is performed in the device operating voltage abnormality determination unit 19 in FIG. 1, and at this time, as described above, it is determined whether or not Vo (min) <Vo <Vo (max), and within the range. In some cases, it is determined as “normal”, and when it is out of the range, it is determined as “abnormal”.

  When it is determined in step S7 of FIG. 2 that the current device operating voltage (Vo) is not within the voltage fluctuation allowable range, the process proceeds to step S8, and a determination result that the current device operating voltage is abnormal is output. This operation is output from the device operating voltage abnormality determination output unit 20 of FIG. On the other hand, when it is determined in step S7 that the current device operating voltage is within the voltage fluctuation allowable range, the process returns to step S1 and the above operation is repeated.

  With the functional block configuration as shown in FIG. 1, the functions shown in FIG. 3 are performed by sequentially operating them according to the operation flow as shown in FIG. That is, FIG. 3A shows a function when the voltage fluctuation allowable rate (α) is a fixed value, and the battery voltage (Vbatt) that fluctuates depending on various loads and the state of charge of the battery is the vehicle first. The voltage is boosted corresponding to the winding ratio by the transformer of the power supply circuit of the mounted device, and the boosted voltage Vo (typ) = Vbatt × n is obtained as a fluctuating reference voltage.

  In the example of FIG. 3A, a voltage fluctuation allowable rate (α) that is a fixed rate of 20% or the like is set up and down, so that the lower limit value Vo (min) is expressed by Vo (typ) × (1−α). The upper limit value Vo (max) is calculated by Vo (typ) × (1 + α). Here, the current operating voltage Vo of the vehicle-mounted device is detected, and it is determined whether or not Vo (min) <Vo <Vo (max). When this condition is satisfied, that is, when it is within the range indicated by hatching in the figure, it is determined as “normal”, and when it is outside the range, it is determined as abnormal.

  In the example of FIG. 3A, the voltage variation allowable rate (α) is set to a fixed value such as 20%. However, in FIG. 3B, the voltage variation allowable rate (α) is variable. In this example, the value is set to a value that can be arbitrarily changed. As a result, appropriate tolerances are set according to the characteristics of each vehicle-mounted device, such as various load variations of the battery, load variations in the vehicle-mounted device itself, variations in parts, and impedance of elements constituting the power supply circuit. It becomes possible.

  In each of the above-described embodiments, the voltage variation allowable rate is set to ± α, and the upper limit and the lower limit are set to the same rate. It is also possible to monitor the fine working voltage. In this case, for example, the upper limit side can be set to a fixed value, and the lower limit side can be set to a variable value.

DESCRIPTION OF SYMBOLS 1 Battery 2 Vehicle mounted equipment 3 Vehicle mounted equipment operating voltage monitoring part 4 Equipment power supply circuit 5 Input signal detection part 6 Vehicle mounted equipment load instruction | indication detection part 7 Vehicle mounted equipment operating part 8 Equipment power supply transformer winding ratio acquisition part 9 Battery voltage detection Unit 10 Device power supply boost voltage detection unit 11 Voltage fluctuation allowable rate setting unit 12 Fixed value setting unit 13 Fluctuation value setting unit 14 Load fluctuation detection unit 15 Ambient environment detection unit 16 Operation instruction detection unit 17 Device operation voltage detection unit 18 Voltage fluctuation tolerance Range calculation unit 19 Device operating voltage abnormality determination unit 20 Device operating voltage abnormality determination output unit

Claims (6)

Battery voltage detection means for detecting the voltage of the battery for the vehicle;
In a vehicle-mounted device that operates using the battery as a power source, a device power transformer transformer winding ratio acquisition unit that acquires a winding ratio of the transformer in a device power circuit that boosts the voltage of the battery with a transformer;
Device power boost voltage detection means for detecting the power boost voltage of the vehicle-mounted device from the battery voltage detected by the battery voltage detection means and the winding ratio acquired by the device power transformer winding ratio acquisition means;
Voltage fluctuation allowable rate setting means for setting a predetermined allowable width above and below the equipment power supply boost voltage detected by the equipment power supply boost voltage detection means as a ratio to the equipment power supply boost voltage;
Voltage fluctuation allowable range calculating means for calculating an upper limit value higher than the device power supply boosted voltage and a lower limit value lower than the device power supply boosted voltage according to the voltage fluctuation allowable rate set by the voltage fluctuation allowable rate setting means;
Device operating voltage detection means for detecting the operating voltage of the vehicle-mounted device;
A device operating voltage abnormality determining unit that determines whether or not a current device operating voltage of the vehicle-mounted device detected by the device operating voltage detecting unit is within an allowable range calculated by the voltage fluctuation allowable range calculating unit;
A device operating voltage that outputs a signal indicating that the device operating voltage is abnormal when it is determined that the device operating voltage abnormality determining means is abnormal by detecting that the current operating voltage of the vehicle-mounted device is not within the allowable range An on-vehicle power supply monitoring system comprising: an abnormality determination output unit.   2. The on-vehicle equipment power supply monitoring system according to claim 1, wherein the voltage fluctuation allowable rate setting means sets the voltage fluctuation allowable rate to a preset fixed ratio.   2. The on-vehicle equipment power supply monitoring system according to claim 1, wherein the voltage fluctuation allowable rate setting means sets the voltage fluctuation allowable rate to an arbitrarily changed ratio.   4. The on-vehicle equipment power supply monitoring system according to claim 3, wherein the changed ratio is set to a ratio corresponding to a load change with respect to a power supply.   The power supply monitoring system for on-vehicle equipment according to claim 3, wherein the changed ratio is set to a ratio corresponding to a change in a surrounding environment of the on-vehicle equipment.   The power supply monitoring system for on-vehicle equipment according to claim 3, wherein the changed ratio changes according to an instruction signal for the vehicle or an instruction signal for the on-vehicle equipment.

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