JP6642241B2 - Instrument - Google Patents

Description

  The present invention relates to an instrument for displaying a measured value such as a remaining fuel amount and a vehicle speed of a motorcycle (two-wheeled vehicle) or a measured value such as a remaining fuel amount and a vehicle speed of a generator. Regarding possible instruments.

  For example, Patent Literature 1 discloses an instrument for a vehicle, and the instrument for a vehicle includes, for example, one first power supply circuit and a plurality of second power supply circuits as power supply units. As shown in FIG. 2 of Patent Document 1, for example, the first power supply circuit of Patent Document 1 is configured by an emitter follower circuit, and a power supply from an alternator mounted on a vehicle (batteryless motorcycle). A voltage can be input through a Zener diode to generate a constant voltage for a control unit (control unit) and a display drive circuit (driver) of a vehicle instrument (see paragraph [0014] of Patent Document 1). The second power supply circuit of Patent Document 1 is also configured by, for example, an emitter follower circuit, and can generate a constant voltage for sensors such as a speed sensor and a fuel sensor (see paragraph [0015] of Patent Document 1).

JP 2009-0673342 A

  However, the power supply unit of Patent Literature 1 needs to include a plurality of power supply circuits according to the number of loads such as a control unit, a driver, and a sensor. Therefore, in the power supply unit of Patent Document 1, the circuit configuration (circuit area) becomes large. On the other hand, it is conceivable that a single power supply circuit shares a plurality of loads. However, in this case, the current flowing through the single power supply circuit increases, and therefore, one power supply circuit for a large current (in other words, one power supply circuit) For example, the manufacturing cost of an instrument including one expensive power supply circuit) increases.

  In addition, the present inventor has recognized that the peak value of the power supply voltage from the alternator may be increased depending on the type of the alternator, and the heat generation amount (power consumption) of the power supply unit may be increased. Similarly, the inventor has recognized that the heat generation (power consumption) of the power supply unit may increase depending on the number and / or type of the loads.

  One object of the present invention is to provide an instrument capable of suppressing heat generation of a power supply unit. Other objects of the present invention will become apparent to those skilled in the art by referring to the aspects and best embodiments exemplified below and the accompanying drawings.

  Hereinafter, embodiments according to the present invention will be exemplified in order to easily understand the outline of the present invention.

In a first aspect, the instrument comprises:
A power supply unit for generating electric power supplied to the sensor,
A switch unit that can enable or disable the supply of the power to the sensor,
A control unit that controls activation or inactivation of the switch unit and generates a measurement value based on a value detected by the sensor.
With
The power supply unit includes a power supply rectification unit that converts alternating current output from the alternator into direct current, and a voltage (first voltage) different from the direct current (first direct current) voltage output from the power supply rectification unit (first voltage). A switching regulator that converts the current into a direct current (second direct current) having a second voltage).
When the switch unit is enabled, the switch unit supplies a direct current (second direct current) having the different voltage (second voltage) to the sensor as the power to the sensor ;
The power rectifier includes a surge cutoff circuit in which a plurality of diodes and a single constant voltage diode are connected in series .

  The present inventor has recognized that when the AC voltage from the alternator rises, only a single constant voltage diode (Comparative Example 1) cuts off the AC voltage. Alternatively, the present inventor has found that in a configuration in which the power supply rectifying unit includes a self-returning type fuse (Comparative Example 2), when the AC voltage from the alternator increases, the control unit cannot generate a measured value, that is, the meter is substantially It did not work.

Therefore, in the first embodiment, even if the AC voltage from the alternator increases, the power supply rectification unit includes not only a single constant voltage diode but also a plurality of diodes so that the instrument continues to function. Can be. Accordingly, in a first aspect, only a single constant-voltage diode surge cut voltage was not enough, it is possible to more diodes Deo offset is an inexpensive circuit configuration.

In a second aspect, the instrument comprises:
A power supply unit for generating electric power supplied to the sensor,
A switch unit that can enable or disable the supply of the power to the sensor,
A control unit that controls activation or inactivation of the switch unit and generates a measurement value based on a value detected by the sensor.
With
The power supply unit includes a power supply rectification unit that converts alternating current output from the alternator into direct current, and a voltage (first voltage) different from the direct current (first direct current) voltage output from the power supply rectification unit (first voltage). A switching regulator that converts the current into a direct current (second direct current) having a second voltage).
When the switch unit is enabled, the switch unit supplies a direct current (second direct current) having the different voltage (second voltage) to the sensor as the power to the sensor,
The switching regulator is configured to output the different voltage (second voltage <first voltage) that is lower than the voltage (first voltage) of the direct current (first direct current) that is the output from the power supply rectifier. 2 voltage) may be a step-down switching regulator that outputs
The power rectifier may receive not only the alternating current output from the alternator but also a direct current (third direct current) from a battery,
The low voltage (second voltage <first voltage) that is the output of the step-down switching regulator is the DC (third DC) voltage (third voltage) that is the output of the battery, and the control unit Is the lower limit value (third voltage) that can be operated, and is set to a value equal to or less than a value obtained by subtracting a voltage drop at the output of the power supply rectification unit from a voltage (third voltage) input to the power supply rectification unit. May be done.

In the second aspect, since the output voltage of the step-down switching regulator is set to be equal to or lower than the input voltage of the step-down switching regulator, the dark current of the step-down switching regulator can be suppressed. In other words, if the output voltage of the step-down switching regulator is set higher than the input voltage of the step-down switching regulator, the dark current will increase.

In a third aspect, the instrument comprises:
A power supply unit for generating electric power supplied to the fuel sensor;
A switch unit that can enable or disable supply of the power to the fuel sensor,
A control unit that controls enabling or disabling of the switch unit and generates a fuel remaining amount based on a value detected by the fuel sensor.
With
The power supply unit includes a power supply rectification unit that converts alternating current output from the alternator into direct current, and a switching regulator that converts output power from the power supply rectification unit into direct current having a voltage different from the DC voltage. Have
When the switch unit is enabled, the switch unit supplies a direct current having the different voltage to the fuel sensor as the power to the fuel sensor;
The fuel remaining amount is a remaining amount related to a distance that a batteryless motorcycle can travel or a remaining amount related to a time when a generator can generate power .

In the third aspect, when the battery-less motorcycle can run, or when the generator can generate power, in other words, when the meter always functions, the heat generation of the power supply unit can be kept suppressed. .

In a fourth aspect of the subordinate to any one aspect of the first to third aspects,
The power supply unit may generate the power that is also supplied to a load other than the sensor,
The instrument is
The power supply apparatus may further include another switch unit that can enable or disable supply of the power to the other load.

In the fourth aspect, even if the number of loads increases, power for a plurality of loads can be generated by a switching regulator having an inexpensive circuit configuration with one power supply unit. In other words, in the fourth aspect, it is not necessary to provide a plurality of power supply circuits, and it is possible to suppress an increase in the size of the power supply unit.

  Those skilled in the art will readily appreciate that the illustrated embodiments according to the present invention may be further modified without departing from the spirit of the invention.

1 shows a specific configuration example of an instrument according to the present invention. 2 shows a specific configuration example of a power supply rectification unit in FIG. 1. 3 shows an output example and an input example of the power supply rectifier of FIG. 2. 2 shows a specific configuration example of the rectifier circuit of FIG. 1. 5 shows an output example and an input example of the rectifier circuit of FIG.

  The preferred embodiments described below are used for easy understanding of the present invention. Accordingly, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

  FIG. 1 shows a specific configuration example of an instrument according to the present invention. As shown in FIG. 1, the meter 1 includes a power supply unit 10 that generates power to be supplied to a sensor (for example, a fuel sensor 15 c) and a switch that can enable or disable supply of power to the fuel sensor 15 c, for example. And a control unit 14 for controlling the activation or inactivation of the switch unit 16c. The control unit 14 (specifically, a microcomputer) calculates a measured value (specifically, the remaining fuel amount) based on a value detected by the sensor (specifically, a voltage based on the resistance value of the fuel sensor 15c). ) Can be generated. When the instrument 1 further includes, for example, the display unit 80, the control unit 14 can cause the display unit 80 to execute a display corresponding to, for example, the remaining fuel amount via the driver 70, for example. In other words, the meter 1 can realize a fuel gauge function on the display unit 80, for example.

  In FIG. 1, a power supply unit 10 (specifically, a constant voltage power supply circuit) includes a power supply rectification unit 50 that converts AC output from the alternator 4 into DC (first DC), A switching regulator 60 for converting the output into a direct current (second current) having a voltage (second voltage) different from the direct current (first direct current) voltage (first voltage). The switching regulator 60 is, specifically, a step-down switching regulator, and can output a voltage (for example, 8 [V]) lower than an average DC voltage (for example, 25 [V]) which is a rectified current. it can. When the switch unit 16c is activated (ON), the switch unit 16c can supply, for example, 8 [V] to the fuel sensor 15c as electric power to the fuel sensor 15c. Note that the resistance value of the fuel sensor 15c changes according to the remaining amount of fuel, and therefore, the current value supplied to the fuel sensor 15c changes, thereby changing the voltage value (output) of the fuel sensor 15c detected by the control unit 14. Value) also changes.

  1 includes a switching regulator 60 as an output stage. In other words, in the meter 1 of FIG. 1, the power supply unit 10 does not need to have, as an output stage, a linear regulator that easily generates heat, such as an emitter-follower circuit (bipolar type linear regulator) disclosed in Patent Document 1, for example. Heat generation of the unit 10 can be suppressed.

  As shown in FIG. 1, the power supply unit 10 generates electric power that is also supplied to loads other than the fuel sensor 15c (specifically, the illumination light source 15a and the remaining fuel warning light 15b). be able to. The instrument 1 may further include another switch unit (specifically, the switch unit 16a and the switch unit 16b) capable of enabling or disabling power supply to the illumination light source 15a and the remaining fuel warning light 15b. it can.

  In the meter 1 of FIG. 1, even when the number of loads increases, a single power supply unit 10 can generate power for a plurality of loads with the switching regulator 60 having an inexpensive circuit configuration. In other words, the instrument 1 does not need to include a plurality of power circuits for a plurality of loads, and can suppress an increase in the size of the power unit 10.

  In FIG. 1, the meter 1 is mounted on, for example, a batteryless motorcycle (two-wheeled vehicle). Therefore, in the example of FIG. 1, not only the AC voltage output from the alternator 4 but also the DC voltage (typically) from the battery (not shown) is supplied to the power supply unit 10 (specifically, the power supply rectification unit 50). Specifically, 12 [V] is also formed to be inputtable, for example, via the battery terminal 11 (specifically, a connector). In other words, when the DC voltage from the battery is supplied or connected to the battery terminal 11, the power supply unit 10 can input the DC voltage from the battery. On the other hand, when the DC voltage from the battery is not supplied or connected to the battery terminal 11, the power supply unit 10 cannot input the DC voltage from the battery. For example, a kick starter (not shown) is mounted on a battery-less type motorcycle, and when a DC voltage from a battery is not supplied to or connected to the battery terminal 11, the rotation of an engine (not shown) started by the kick starter is used as a power source. The alternator 4 can generate electric power.

  When a battery is connected to the battery terminal 11 to which the output of the alternator 4 is connected, the node of the battery terminal 11 can be stabilized with a DC voltage. On the other hand, when a battery is not connected to the battery terminal 11, a power source is constituted by, for example, a half-wave AC from the alternator 4 at the node of the battery terminal 11. Further, for example, when a batteryless motorcycle includes a starter switch (not shown) and a battery is connected to the battery terminal 11, the starter switch can also start the engine with electric power (power) from the battery. .

  In addition, in the example of FIG. 1, when the ignition switch 3 is turned on, the output from the alternator 4 is also connected to or input to the ignition terminal 12 (specifically, a connector). The instrument 1 includes, for example, a rectifier circuit 13, and the controller 14 typically receives an output of 8 [V] from the rectifier circuit 13, and the controller 14 sets the value to a threshold (eg, 2 [V]). Is exceeded, the ON state of the ignition switch 3 can be detected. 1 can detect ON or OFF of the ignition switch 3, and when the ignition switch 3 is OFF, the control unit 14 does not activate (ON) the switch unit 16. On the other hand, when the ignition switch 3 is ON, the control unit 14 can enable (ON) the switch unit 16.

  When the ignition switch 3 is turned on, for example, the control unit 14 can permit the start of the engine. Further, when the ignition switch 3 is changed from the ON state to the OFF state, for example, the control unit 14 can stop the engine.

  The control unit 14 can recognize that the engine has started when the output voltage from the rectifier circuit 13 is always higher than a threshold value (for example, 2 [V]). After recognizing that the engine has been started, the control unit 14 activates (ON) the switch unit 16a, and turns on the illumination light source 15a as a backlight of the display unit 80 including a liquid crystal element such as a TFT. Can be done. The control unit 14 activates (ON) the switch unit 16b and turns on the remaining fuel warning light 15b when the remaining fuel amount (in FIG. 1, the remaining amount related to the distance that the battery-less motorcycle can travel) is small. be able to.

  In the example of FIG. 1, the meter 1 can further include, for example, a linear regulator 90 at a stage subsequent to the power supply unit 10, and the linear regulator 90 is typically provided with an operating power supply of the control unit 14 (typically, 5 [V]) can be generated or formed.

  FIG. 2 shows a specific configuration example of the power supply rectification unit 50 of FIG. As shown in FIG. 2, preferably, power supply rectification unit 50 is configured by a half-wave power supply rectification circuit having a surge cutoff circuit. The anode of the diode 51 of the half-wave power rectifier circuit is connected to the battery terminal 11, and the cathode of the diode 51 is connected to the positive side of the electrolytic capacitor 53 of the half-wave power rectifier circuit. The anode of the diode 52 of the half-wave power supply rectifier circuit is connected to the ignition terminal 12, and the cathode of the diode 52 is also connected to the + side of the electrolytic capacitor 53.

  FIG. 3 shows an output example and an input example of the power supply rectifier 50 (specifically, a half-wave power supply rectifier circuit) of FIG. When a half-wave power rectifier circuit of the power rectifier 50 is configured by the diode 51, the diode 52, and the electrolytic capacitor 53 in FIG. 2, an example of an electric waveform before power rectification is, for example, a broken line in FIG. 50 inputs 50in). In addition, an example of an electric waveform after power supply rectification can be represented by, for example, a solid line (output 50out of the power supply rectification unit 50) in FIG. In the example of FIG. 2, the half-wave power supply rectifier circuit includes diodes 51 and 52 and an electrolytic capacitor 53, but is not limited thereto, and includes another circuit that rectifies an AC power supply to a DC power supply. You may.

  In the example of FIG. 2, the surge cutoff circuit of the power supply rectifier 50 includes a single constant voltage diode 55 (zener diode) and a plurality of diodes 54a to 54d, and includes a constant voltage diode 55 and a plurality of diodes 54a to 54d. Are connected in series. The surge cutoff circuit may include only the constant voltage diode 55 (an example other than the example in FIG. 2 or Comparative Example 1), but preferably further includes a plurality of diodes 54a to 54d (an example in FIG. 2). . The inventor has recognized that the voltage resulting from the output from the alternator 4 may be higher on the positive side of the electrolytic capacitor 53 than the surge cut-off voltage of the constant voltage diode 55, and a plurality of diodes 54a to 54d connected in series. Is arranged between the electrolytic capacitor 53 and the constant voltage diode 55. With such an arrangement (the example in FIG. 2), the surge cut voltage is intentionally offset.

  As an example, the surge cut circuit includes only the constant voltage diode 55 having a surge cut voltage of, for example, 27 [V] (Example other than the example in FIG. 2 or Comparative Example 1), and a voltage exceeding the surge cut voltage is, for example, When present on the + side of the electrolytic capacitor 53 due to the lightning surge voltage, the power supply rectification unit 50 can invalidate the node of the battery terminal 11 as an emergency operation (for example, when the lightning surge current is supplied to the control unit 14). Intrusion can be prevented). In other words, when the power supply voltage of the alternator 4 is low and the voltage resulting from the output from the alternator 4 does not exist on the + side of the electrolytic capacitor 53, the power supply rectification unit 50 (the embodiment other than the example in FIG. 2 or the comparative example 1) Can enable the node of the battery terminal 11 as a normal operation. On the other hand, the present inventor has recognized that depending on the type of the alternator 4, the power supply voltage of the alternator 4 may be high, and when the voltage resulting from the output from the alternator 4 exists on the + side of the electrolytic capacitor 53, The unit 50 (the embodiment other than the example in FIG. 2 or the comparative example 1) invalidates the node of the battery terminal 11 as a normal operation. That is, even if the power supply voltage of the alternator 4 is high in order for the meter 1 to continue to function, the power supply rectification unit 50 (the example in FIG. 2) activates the node of the battery terminal 11 as a normal operation. Can be. Specifically, according to the maximum output voltage of the alternator 4, in the example of FIG. 2, the surge cut circuit further includes, for example, four diodes 54a to 54d.

  By the way, as an example other than the example of FIG. 2 or a comparative example 2, the surge cut-off circuit of the power supply rectification unit 50 does not include a single constant voltage diode 55 and a plurality of diodes 54a to 54d. (Not shown). However, the present inventor has recognized that when the AC voltage from the alternator 4 increases, the control unit 14 cannot generate a measurement value, that is, the meter 1 does not substantially function.

  In addition, as an example other than the example of FIG. 2 or Comparative Example 3, the surge cutoff circuit of the power supply rectification unit 50 is not constituted by a single constant voltage diode 55 and a plurality of diodes 54a to 54d. It may include a constant voltage diode (not shown) connected in series. However, when the surge cutoff circuit of the power supply rectifier 50 (the embodiment other than the example of FIG. 2 or the comparative example 3) includes two constant voltage diodes 55 having a surge cutoff voltage of, for example, 27 [V], The surge cut voltage is, for example, 54 [V]. The breakdown voltage of, for example, the switching regulator 60 shown in FIG. 1 disposed at the output stage of the power supply unit 10 is typically about 40 [V]. Will break. In order to prevent this, in the example of FIG. 2, a single constant voltage diode 55 and a plurality of diodes 54a to 54d are inserted in series.

  In general, the switching regulator is preferably a step-up / step-down switching regulator. However, since the step-up / step-down switching regulator is expensive, the switching regulator 60 in FIG. 1 is configured as a step-down switching regulator, for example. As shown by the solid line in FIG. 3, the voltage after power rectification input to the switching regulator 60 is much higher than the rated voltage of a normal battery (typically, 12 [V]). Therefore, if the power supply unit 10 shown in FIG. 1 does not include the switching regulator 60 and a linear regulator 90 that generates, for example, 5 [V] is used as the output stage of the power supply unit 10, the linear regulator 90 itself generates heat. Will be expensive. Alternatively, it is necessary to employ a large or large heat sink for the linear regulator 90 as an output stage of the power supply unit 10. In order to solve such a problem, the power supply unit 10 of FIG. 1 uses the switching regulator 60 as its output stage, and can sufficiently suppress heat generation of the constant voltage power supply circuit.

  In addition, by setting the step-down voltage of the switching regulator 60 constituted by, for example, a step-down switching regulator to, for example, 8 [V], in other words, the illumination light source 15a, the remaining fuel warning light 15b, the fuel sensor 15c, and the like. By setting the power supply of the load to, for example, 8 [V], the heat generation of the load itself can also be suppressed, and such a switching regulator 60 can reduce the heat generation of the entire instrument 1.

  It is preferable that the dark current of the switching regulator 60 is suppressed when the switching regulator 60 is applied to the instrument 1 of a motorcycle that can run without a battery. Similarly, the switching regulator 60 is provided with a meter 1 (a remaining amount related to a time when the generator can generate power) of a generator (not shown) (for example, an emergency generator that can generate power using gasoline and generate a household power supply). Can be measured or displayed), and also in this case, the dark current of the switching regulator 60 is preferably suppressed. When the instrument 1 is applied to, for example, a battery-less motorcycle, the instrument 1 preferably has, for example, a clock function. Further, even in a batteryless motorcycle, when the battery is connected to the battery terminal 11, it is preferable that the meter 1 always operates its clock function with, for example, a DC voltage (power supply) from the battery. In this case, the dark current of the meter 1 is preferably suppressed so that the power of the battery is not wasted.

  When the switching regulator 60 in FIG. 1 is a step-down switching regulator, the output voltage (second voltage) of the step-down switching regulator is a DC voltage (third voltage) of the battery, and the lower limit at which the control unit 14 can operate. From the voltage (eg, 9 [V]: the third voltage) and the input voltage of the power supply rectification unit 50 (the voltage of the anode of the diode 51: the third voltage) to the output of the power supply rectification unit 50 (the cathode of the diode 51). (For example, 0.8 [V] which is a voltage drop at the diode 51) (eg, 8.2 [V] = 9.0 [V] -0.8 [voltage]). V]). Specifically, when the battery is weakened to, for example, 9 [V] and the voltage drop in the diode 51 is, for example, 0.8 [V], the input voltage of the step-down switching regulator becomes 8.2 [V]. V] (= 9.0 [V] -0.8 [V]).

  Even when the battery is weak, when the output voltage of the step-down switching regulator is set to be equal to or lower than the input voltage of the step-down switching regulator (in FIG. 1, the output voltage of the step-down switching regulator = 8.0 [V]). The instrument 1 can suppress the dark current of the step-down switching regulator. In other words, if the battery is weakened and the output voltage of the step-down switching regulator is set to be higher than the input voltage of the step-down switching regulator (output voltage of the step-down switching regulator> 9.0 [V]), The dark current of the step-down switching regulator increases.

  FIG. 4 shows a specific configuration example of the rectifier circuit 13 of FIG. As shown in FIG. 4, the rectifier circuit 13 is a circuit that rectifies a half-wave alternating current by charging and discharging. At the time of charging, the charge of the capacitor 13c is charged by a charging circuit composed of the resistor 13b and the capacitor 13c, while at the time of discharging, the charge of the capacitor 13c is discharged to GND via the resistor 13d. The diode 13a is employed or inserted in the input stage of the rectifier circuit 13 so that the discharge current of the capacitor 13c does not flow backward to the ignition terminal 12 side and the discharge is accelerated.

  FIG. 5 shows an output example and an input example of the rectifier circuit 13 of FIG. When the rectifier circuit 13 is configured by the diode 13a, the resistor 13b, the capacitor 13c, and the resistor 13d in FIG. 4, an example of an electric waveform before rectification is represented by, for example, a broken line (input 13in of the rectifier circuit 13) in FIG. be able to. In addition, an example of the electrical waveform after rectification can be represented by, for example, a solid line (output 13out of the rectifier circuit 13) in FIG.

  The rectifier circuit 13 of FIG. 1 can be configured in the example of FIG. 4, but is not limited to the example of FIG. 4, and the rectifier circuit 13 of FIG. 1 is configured of another circuit that rectifies an alternating current into a direct current. You may. When the rectifier circuit 13 of FIG. 1 is configured in the example of FIG. 4, the half-wave AC waveform shown by a broken line in FIG. 5 is close to a DC signal and is rectified into a triangular wave shown by a solid line in FIG. The resistance constant and the capacitor constant of the rectifier circuit 13 are optimized so that the voltage is always higher than a threshold value (for example, 2 [V]) of the control unit 14.

  The present invention is not limited to the exemplary embodiments described above, and those skilled in the art will be able to easily modify the exemplary embodiments described above to the scope included in the claims. .

  DESCRIPTION OF SYMBOLS 1 ... Instrument, 3 ... Ignition switch, 4 ... Alternator, 10 ... Power supply part, 11 ... Battery terminal, 12 ... Ignition terminal, 13 ... Rectifier circuit, 14 ... Control unit, 15a: illumination light source, 15b: remaining fuel warning light, 15c: fuel sensor, 16a, 16b, 16c: switch unit, 50: power supply rectification unit, 54a, 54b , 54c, 54d: Diode, 55: Constant voltage diode (Zener diode), 60: Switching regulator, 70: Driver, 80: Display unit, 90: Linear regulator.

Claims (4)

A power supply unit for generating electric power supplied to the sensor,
A switch unit that can enable or disable the supply of the power to the sensor,
A control unit that controls activation or inactivation of the switch unit and generates a measurement value based on a value detected by the sensor.
With
The power supply unit includes a power supply rectification unit that converts alternating current output from the alternator into direct current, and a switching regulator that converts output power from the power supply rectification unit into direct current having a voltage different from the DC voltage. Have
When the switch unit is enabled, the switch unit supplies a direct current having the different voltage to the sensor as the power to the sensor ,
The power supply rectifier includes a surge cutoff circuit in which a plurality of diodes and a single constant voltage diode are connected in series . A power supply unit for generating electric power supplied to the sensor,
A switch unit that can enable or disable the supply of the power to the sensor,
A control unit that controls activation or inactivation of the switch unit and generates a measurement value based on a value detected by the sensor.
With
The power supply unit includes a power supply rectification unit that converts alternating current output from the alternator into direct current, and a switching regulator that converts output power from the power supply rectification unit into direct current having a voltage different from the DC voltage. Have
When the switch unit is enabled, the switch unit supplies a direct current having the different voltage to the sensor as the power to the sensor,
The switching regulator is a step-down switching regulator that outputs the different voltage that is lower than the DC voltage that is the output from the power rectifier,
In the power rectifier, not only the alternating current output from the alternator, but also a direct current from a battery is input,
The low voltage that is the output of the step-down switching regulator is the DC voltage that is the output of the battery, is the lower limit value at which the control unit can operate, and the voltage that is the input of the power supply rectification unit. from a total unit shall be the values are less than the value obtained by subtracting the voltage drop amount at the output of the power supply rectifier. A power supply unit for generating electric power supplied to the fuel sensor;
A switch unit that can enable or disable supply of the power to the fuel sensor,
A control unit that controls enabling or disabling of the switch unit and generates a fuel remaining amount based on a value detected by the fuel sensor.
With
The power supply unit includes a power supply rectification unit that converts alternating current output from the alternator into direct current, and a switching regulator that converts output power from the power supply rectification unit into direct current having a voltage different from the DC voltage. Have
When the switch unit is enabled, the switch unit supplies a direct current having the different voltage to the fuel sensor as the power to the fuel sensor;
The remaining fuel amount is a total unit you wherein the remaining amount or generator batteryless type motorcycle of possible distance travel is residual of possible time power generation. The power supply unit generates the power that is also supplied to a load other than the sensor,
The other instruments according to any one of claims 1 to 3 characterized in that said further comprising enabling or disabling other possible switch unit supplies power to the load.

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