JP2013061153A - Remaining liquid quantity detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a remaining liquid quantity detection system capable of highly accurately detecting current remaining quantity of liquid stored in a container even when supply voltage of a power source fluctuates.SOLUTION: A liquid level sensor 20 has: a sensor regulator 31 which stabilizes meter supply voltage applied by a meter regulator 50; and a signal output section 35 which varies frequency tc of a detection signal depending on the height of a liquid level 91 of a fuel. A meter control circuit 40 generates detection voltage on the basis of the detection signal output from the signal detection section 35 as well as the meter supply voltage. The meter control circuit 40 also acquires voltage variation ΔV during a predetermined time Δt when the detection signal falls in a proportional range PR where a value of the detection signal varies in proportion to elapsed time. Then, the meter control circuit 40 converts the acquired current voltage variation ΔV into remaining quantity information on the basis of a data table where a correlation between the voltage variation ΔV and the remaining quantity of the fuel is preliminarily specified.

Description

  The present invention relates to a liquid remaining amount detection system that detects the remaining amount of liquid stored in a container.

  Conventionally, a liquid remaining amount detection system is connected to a power source, and detects the remaining amount of liquid such as fuel by using electric power supplied from the power source. As one type of such a liquid remaining amount detection system, for example, the configuration disclosed in Patent Document 1 is a system that detects the remaining amount of fuel as a liquid, and includes a non-contact sensor, a sensor output conversion circuit, and a CPU. I have.

  In the configuration disclosed in Patent Document 1, the non-contact sensor outputs a pulse having a duty ratio corresponding to the liquid level of the fuel when a power supply voltage is applied by a power source. The sensor output conversion circuit generates an analog voltage corresponding to the duty ratio of the pulse output from the non-contact sensor. An input voltage based on the analog voltage output from the sensor output conversion circuit and the power supply voltage of the power supply is input to the CPU. The CPU stores a data table that predefines the correspondence between the input voltage and the remaining amount of fuel. The CPU converts the input voltage based on the data table, and acquires information indicating the current remaining amount of fuel.

Japanese Patent No. 4199149

  In recent years, non-contact type liquid level sensors having a sensor power supply unit that stabilizes a power supply voltage by a power supply have been used. Such a liquid level sensor outputs a detection signal corresponding to the liquid level by using electric power whose voltage is stabilized by the sensor power supply unit. Therefore, even if the power supply voltage applied from the power source to the liquid level sensor fluctuates, the output detection signal does not easily fluctuate.

  However, as in the configuration disclosed in Patent Document 1, generally, a voltage input to a CPU is generated based on a detection signal such as an analog voltage output from a liquid level sensor and a power supply voltage by a power supply. Therefore, even if the detection signal is not easily affected by fluctuations in the power supply voltage, the input voltage input to the CPU increases or decreases due to fluctuations in the power supply voltage. As described above, the change in the value of the detection signal by the liquid level sensor is acquired by the CPU because the ratiometric configuration does not correspond to the increase or decrease in the power supply voltage by the power supply and the increase or decrease in the detection signal by the liquid level sensor. The information indicating the remaining amount of fuel is not accurately reflected. Therefore, when the power supply voltage by the power supply fluctuates, it is difficult to detect the remaining amount of liquid stored in the container with high accuracy.

  The present invention has been made in view of the above problems, and its purpose is to detect the current remaining amount of liquid stored in the container with high accuracy even if the power supply voltage fluctuates. It is to provide a detection system.

  In order to achieve the above-mentioned object, the invention according to claim 1 is a liquid residue which is connected to a power source and detects the remaining amount of liquid stored in the container by using electric power supplied from the power source. The sensor power supply unit that stabilizes the power supply voltage applied by the power supply, and the sensor voltage stabilized by the sensor power supply unit changes the value in proportion to the passage of time. A liquid level sensor having a signal output unit that repeatedly outputs a detection signal including a proportional range and changes a cycle of the detection signal according to the liquid level of the liquid, and a detection signal and a power source output from the signal output unit An acquisition unit that generates a detection voltage based on the voltage and acquires a change amount of the detection voltage at a preset time when the detection signal is in a proportional range, and a correspondence between the change amount and the remaining amount of liquid Predefined Storing correspondence information, and a converting means for converting the information indicating the remaining amount based on the current change amount obtained by the obtaining means corresponding information.

  According to this invention, the detection voltage generated in the acquisition unit is based on the detection signal output from the signal output unit. Therefore, the detection voltage periodically changes following the detection signal that is repeatedly output. As described above, when the signal output unit changes the period of the detection signal according to the liquid level of the liquid stored in the container, the amount of change in the detection voltage at a predetermined time set in advance also increases or decreases. Therefore, when the detection signal is in a proportional range where the value changes in proportion to the passage of time, the amount of change in the detection voltage acquired by the acquisition means corresponds to the liquid level of the liquid stored in the container. obtain.

  In addition, the fluctuation of the power supply voltage at a predetermined time when the change amount of the detection voltage is acquired is very small compared with the fluctuation of the detection signal at the predetermined time. Therefore, the change amount of the detection voltage in the predetermined time is not easily affected by the fluctuation of the power supply voltage. By converting the amount of change in the detection voltage as described above based on the correspondence information defined in advance, information indicating the remaining amount of the liquid accurately reflecting the change in the period of the detection signal by the liquid level sensor is converted. Generated by means. Therefore, the liquid remaining amount detection system can detect the current remaining amount of the liquid stored in the container with high accuracy even if the power supply voltage by the power source fluctuates.

  According to a second aspect of the present invention, the detection signal is characterized in that the time in the proportional range is longer than the time excluding the proportional range per waveform for one period.

  According to the present invention, in the detection signal for one cycle, the time that is the proportional range is set longer than the time that excludes the proportional range, so that it is easy to secure the time during which the change amount of the detection voltage can be acquired. Therefore, the acquisition unit can stably acquire the change amount of the detection voltage in a predetermined time. As described above, even when the remaining amount of liquid is detected by changing the period of the detection signal, the reliability of the operation for detecting the remaining amount is maintained high.

  According to the third aspect of the present invention, the detection signal is a proportional range that changes from the initial value to the maximum amplitude value in proportion to the passage of time, and the maximum amplitude value to the initial value at a time shorter than the time that is the proportional range. It is characterized by a saw-tooth waveform including a return range returning to.

  As in the present invention, the value in the sawtooth waveform changes from the initial value to the maximum amplitude value in proportion to the passage of time, and returns from the maximum amplitude value to the initial value in a short time. Therefore, the time of the proportional range in the waveform for one cycle can be surely secured longer than the time of the return range excluding the proportional range. According to the above, since the acquisition of the change amount of the detection voltage by the acquisition unit becomes stable, the certainty of the operation for detecting the remaining amount of liquid is further increased. Therefore, the sawtooth wave detection signal is particularly suitable as the output of the liquid level sensor that changes the period according to the liquid level of the liquid.

  The invention according to claim 4 is characterized in that the predetermined time preset in the acquisition means is shorter than the time in the proportional range when the period of the detection signal is minimized.

  According to the present invention, even when the period of the detection signal is minimized by the signal output unit, the predetermined time for acquiring the change amount of the detection voltage can be ensured in the proportional range of the detection signal. As described above, the acquisition unit can reliably acquire the change amount of the detection voltage in the predetermined time regardless of the length of the cycle of the detection signal. Therefore, the certainty of detection of the remaining amount by the liquid remaining amount detection system is further improved.

  The invention according to claim 5 is characterized in that the signal output unit reduces the change width of the value in the proportional range of the detection signal as the period of the detection signal is increased.

  According to the present invention, when the period of the detection signal is increased, the change width of the detection signal value in the proportional range, and hence the change width of the detection voltage value in the acquisition unit is reduced. Therefore, when the period of the detection signal is long, the change amount of the detection voltage in the predetermined time acquired by the acquisition unit is further reduced as compared with the form in which the change width in the proportional range is constant regardless of the period. In the above embodiment, since the increase / decrease width of the change amount of the detection voltage that changes in accordance with the liquid level height can be expanded, the output from the liquid level sensor is further added to information indicating the remaining amount acquired by the acquisition unit. It can be accurately reflected. Therefore, the liquid remaining amount detection system can detect the current remaining amount of the liquid stored in the container with higher accuracy.

It is a block diagram which shows the electric constitution of the fuel residual amount detection system by one Embodiment of this invention. It is a figure for demonstrating the structure of a liquid level sensor, Comprising: (a) is a perspective view of a liquid level sensor, (b) is a front view which shows the liquid level sensor in a fuel tank. It is a figure explaining the detection signal output from a liquid level sensor in detail. It is a figure which shows the waveform of the detection signal output from a liquid level sensor, Comprising: (a) shows a detection signal when a liquid level is the highest, (b) shows a detection signal when a liquid level is the lowest. It is a flowchart which shows the process in which a meter control circuit acquires the residual amount information of a fuel. It is a figure which shows the other waveform of the detection signal output from a liquid level sensor, and is a figure which shows the modification of Fig.4 (a).

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an electrical configuration of a remaining fuel amount detection system 100 according to an embodiment of the present invention. FIG. 2 is a diagram showing a mechanical configuration of the liquid level sensor 20. 1 and 2 detects the remaining amount of fuel stored in the fuel tank 90 of the vehicle, and outputs the detection result toward the fuel meter 60 provided in the combination meter 80. Output.

  As shown in FIG. 1, the remaining fuel amount detection system 100 includes the liquid level sensor 20 described above, a meter control circuit 40 provided in the combination meter 80, and the like. Further, the remaining fuel amount detection system 100 is connected to a meter regulator 50 and a fuel meter 60 provided in the combination meter 80.

  The liquid level sensor 20 is a two-wire fuel sender that is connected to the combination meter 80 by a power line 45 and a ground line 46. The power supply line 45 and the ground line 46 are low-voltage electric wires for automobiles formed by covering conductive wires with an insulating material such as vinyl. The power line 45 and the ground line 46 have a length of about 5 to 6 m as a distance between the fuel tank 90 and the combination meter 80 in the vehicle. The power line 45 has a function of a power line for supplying power from the meter regulator 50 to the liquid level sensor 20 and a function of a signal line for transmitting the output of the liquid level sensor 20 to the meter control circuit 40. The ground line 46 is grounded, for example, to the vehicle body.

  As shown in FIGS. 2A and 2B, the liquid level sensor 20 includes a float 21, a magnet holder 23, a float arm 24, and a housing 25.

  The float 21 is formed in a rectangular parallelepiped shape with a small thickness by a material having a small specific gravity such as foamed ebonite. The float 21 can be floated on the liquid level 91 of the fuel by being formed of a material having a specific gravity smaller than that of the fuel. In the float 21, a through-hole for externally fitting to the float arm 24 is formed so as to pass through the center of gravity of the float 21.

  The magnet holder 23 is formed into a cylindrical shape using, for example, polyacetal (POM) resin having excellent oil resistance, solvent resistance, and mechanical properties. The magnet holder 23 is rotatably supported by the housing 25 by a bearing portion formed on the inner peripheral surface thereof. A pair of magnets (not shown) exhibiting ferromagnetism are fixed to the magnet holder 23. The pair of magnets are arranged so as to face each other with the central axis of the bearing portion interposed therebetween, and rotate integrally with the magnet holder 23.

  The float arm 24 is formed of a round bar-shaped core material made of a metal material such as stainless steel. The float 21 is held at one end of both ends of the float arm 24. The other end of the float arm 24 is held by a magnet holder 23.

  The housing 25 is formed into a rectangular plate shape using polyphenylene sulfide (PPS) resin or the like that is not affected by an organic solvent such as fuel and does not decrease in strength even at high temperatures. The housing 25 is attached to a wall surface of a fuel pump module (not shown) or the like with its longitudinal direction oriented in the vertical direction, and fixes the liquid level sensor 20 to the fuel tank 90. The housing 25 is provided with a support shaft that rotatably supports the bearing portion of the magnet holder 23.

  With the above configuration, the reciprocating motion of the float 21 that moves up and down following the fuel level 91 by the float arm 24 is converted into a rotational motion and transmitted to an integral element composed of the float arm 24 and the magnet holder 23. . Therefore, the magnet holder 23 follows the liquid level 91 of the fuel stored in the fuel tank 90 and rotates relative to the housing 25.

  As shown in FIGS. 1 and 2, the liquid level sensor 20 includes a sensor regulator 31, a hall element 33, and a signal output unit 35 as an electrical configuration.

  The sensor regulator 31 is connected to the meter regulator 50 through the power line 45. For example, a meter power supply voltage of 5 volts (V) is applied to the sensor regulator 31 from the meter regulator 50. The sensor regulator 31 stabilizes the meter power supply voltage applied by the meter regulator 50, and generates a sensor voltage of, for example, 3V. The sensor regulator 31 applies the stabilized sensor voltage to the hall element 33 and the signal output unit 35.

  The hall element 33 is connected to the sensor regulator 31 and the signal output unit 35. The Hall element 33 is applied with a sensor voltage stabilized by the sensor regulator 31. The hall element 33 is provided in the support shaft of the housing 25 and is positioned so as to be sandwiched between a pair of magnets embedded in the magnet holder 23. The Hall element 33 forms an angle sensor that detects the rotation angle of the magnet holder 23 relative to the housing 25 in cooperation with the pair of magnets. In the above configuration, the magnet rotates integrally with the magnet holder 23 as the fuel level 91 rises and falls. As a result, the density of magnetic flux passing through the Hall element 33 changes. The Hall element 33 to which the sensor voltage is applied converts the change in the density of the magnetic flux passing through the Hall element 33 into an electric signal and outputs it to the signal output unit 35.

  The signal output unit 35 is a circuit that outputs a detection signal corresponding to the height of the fuel level 91 to the combination meter 80. The signal output unit 35 is connected to the sensor regulator 31 and the hall element 33. The signal output unit 35 is applied with a sensor voltage by the sensor regulator 31. The signal output unit 35 to which the sensor voltage is applied generates a detection signal based on the electric signal output from the Hall element 33 and outputs the detection signal to the combination meter 80.

  The meter control circuit 40 of the combination meter 80 is mainly composed of a microcomputer that performs various calculations by executing a predetermined program. A detection signal output from the signal output unit 35 is input to the meter control circuit 40 through the power supply line 45, and a meter power supply voltage from the meter regulator 50 is input through the power supply line 47. The meter control circuit 40 generates a detection voltage based on these detection signals and the meter power supply voltage. The meter control circuit 40 calculates a value indicating the height of the fuel level 91 in the fuel tank 90 and, by extension, the remaining amount of fuel (hereinafter referred to as “remaining amount information”) by measuring the detected voltage. The meter control circuit 40 generates a display signal for controlling the display of the fuel gauge 60 based on the remaining quantity information that is the detection result of the remaining fuel quantity detection system 100, and outputs the display signal to the fuel gauge 60.

  The meter regulator 50 is connected to a battery or the like mounted on the vehicle, and power is supplied from the battery. The meter regulator 50 is connected to the liquid level sensor 20 and the meter control circuit 40 through power lines 45 and 47. The meter regulator 50 converts the power supplied from the battery into a meter power supply voltage suitable for the operation of the liquid level sensor 20 and the meter control circuit 40, and supplies these to the elements 20, 40 and the like.

  The fuel gauge 60 is a display that forms a display for notifying the viewer of the remaining amount of fuel stored in the fuel tank 90. The fuel gauge 60 includes a dial on which numerals and letters are formed, a pointer that points to the numeral on the dial, a stepping motor that rotates the pointer, and the like. The stepping motor rotates the pointer based on a display signal output from the meter control circuit 40 of the meter control circuit 40, specifically, a digital pulse. As a result, a display indicating the remaining amount of fuel is formed on the fuel gauge 60.

  Next, the operation of detecting the remaining amount of fuel in the fuel tank 90 by using the power supplied from the meter regulator 50 by the fuel remaining amount detection system 100 having the above configuration will be described in detail.

  The detection signal output from the signal output unit 35 to the power supply line 45 is a digital signal having a resolution of, for example, 10 bits (about 1 mV). As shown in FIG. 3, a voltage that changes in the range of 3 to 4 volts is output from the signal output unit 35 as a detection signal. Specifically, the meter power supply voltage by the meter regulator 50 may also vary between 4 and 5 V due to the fluctuation of the voltage supplied to the meter regulator 50 from the outside of the combination meter 80. On the other hand, the sensor voltage by the sensor regulator 31 for driving the Hall element 33 is 3V. Thus, the voltage as the detection signal output to the power supply line 45 is set to increase or decrease in a range of 3 to 4 V that avoids the fluctuation of the meter power supply voltage and is higher than the sensor voltage.

  As shown in FIGS. 1 and 4, the detection signal has a sawtooth waveform. The detection signal has a proportional range PR that changes from a specific initial value (for example, 3V) as a reference in proportion to the passage of time to a value that has a maximum amplitude (for example, 4V), and a time that is shorter than the time that is the proportional range PR. It includes a return range that returns from the maximum amplitude value to the initial value. In such a sawtooth detection signal, the time in the proportional range PR is longer than the time excluding the proportional range PR per waveform for one period. In particular, in the present embodiment, the return range is substantially zero (hence, the return range is not shown).

  The signal output unit 35 repeatedly outputs the above detection signal. The signal output unit 35 changes the cycle tc of the detection signal to be output according to the fuel level. Specifically, when the liquid level of the fuel detected by the Hall element 33 is the highest, the signal output unit 35 shortens the cycle tc of the detection signal, and changes the value of the detection signal. Is maximized (see FIG. 4A). Then, as the fuel level detected by the Hall element 33 decreases, the signal output unit 35 increases the period tc of the detection signal. In addition, the signal output unit 35 decreases the amplitude Av as the period tc of the detection signal is increased. When the fuel level detected by the Hall element 33 is the lowest, the signal output unit 35 maximizes the period tc of the detection signal and minimizes the amplitude Av of the detection signal (see FIG. 4 (b)).

  The detection voltage generated by the meter control circuit 40 based on the above detection signal periodically changes following the detection signal repeatedly output. On the other hand, as described above, the power supply line 45 also functions as a signal line for transmitting a detection signal, and the meter power supply voltage is applied to the meter control circuit 40 through the power supply line 47, thereby detecting The voltage also changes due to fluctuations in the meter power supply voltage.

  When the detection signal is in the proportional range PR, the meter control circuit 40 acquires the amount of change in the detected voltage (hereinafter referred to as “voltage change amount ΔV”) at a predetermined time Δt (for example, 30 milliseconds). The predetermined time Δt is set in advance so as to be shorter than the time of the proportional range PR when the period tc of the detection signal is minimized by the signal output unit 35. In the present embodiment, the voltage change amount ΔV at the predetermined time Δt decreases as the liquid level of the fuel decreases. The meter control circuit 40 acquires a voltage change amount ΔV that increases or decreases according to the liquid level of the fuel as digital information with a predetermined resolution.

  The meter control circuit 40 stores a data table as correspondence information in which the correspondence between the voltage change amount ΔV and the remaining amount of fuel is defined in advance. The meter control circuit 40 converts the current voltage change amount ΔV into remaining amount information based on a previously stored data table, and acquires it as a detection result. With the above configuration, when the voltage change amount ΔV is maximum (see FIG. 4A), the meter control circuit 40 acquires remaining amount information indicating that the remaining amount of fuel is maximum. On the other hand, when the voltage change amount ΔV is minimized (see FIG. 4B), the meter control circuit 40 acquires remaining amount information indicating that the remaining amount of fuel is small.

  Next, a process in which the meter control circuit 40 of the meter control circuit 40 acquires the remaining amount information will be described with reference to FIG. The process shown in the flowchart of FIG. 5 is started by the meter control circuit 40 when the application of the meter power supply voltage from the meter regulator 50 to the meter control circuit 40 is started. This process is repeatedly performed by the meter control circuit 40 until the application of the meter power supply voltage is stopped.

  In S101, the detection voltage is monitored to determine the timing for acquiring the voltage change amount ΔV, and the process proceeds to S102. In S102, when the timing determined in S101, that is, when the detection signal output from the signal output unit 35 is within the proportional range PR, the voltage change amount ΔV during the predetermined time Δt is acquired, and the process proceeds to S103. In S103, based on the data table, the current voltage change amount ΔV acquired in S102 is converted into remaining amount information, and the process proceeds to S104. In S104, a display signal is output to the fuel gauge 60 based on the remaining amount information converted in S103, and the process returns to S101. Based on the display signal output in S104, the fuel gauge 60 displays the current remaining amount of fuel.

  In the present embodiment described so far, when the cycle tc of the detection signal changes in accordance with the liquid level of the fuel stored in the fuel tank 90, the voltage change amount ΔV at the predetermined time Δt also increases or decreases. Therefore, the voltage change amount ΔV acquired by the meter control circuit 40 when in the proportional range PR can correspond to the liquid level of the fuel stored in the fuel tank 90. In addition, the fluctuation of the meter power supply voltage at the predetermined time Δt when the voltage change amount ΔV is acquired is negligible compared to the fluctuation of the detection signal at the predetermined time Δt. Therefore, the voltage change amount ΔV is hardly affected by fluctuations in the meter power supply voltage. As described above, the remaining amount information that accurately reflects the change in the period tc of the detection signal by the liquid level sensor 20 is acquired by the meter control circuit 40. Therefore, the remaining fuel amount detection system 100 can detect the current remaining amount of fuel stored in the fuel tank 90 with high accuracy even if the meter power supply voltage fluctuates.

  In addition, in the present embodiment, in the detection signal for one period, the time that is the proportional range PR is set longer than the time that excludes the proportional range PR. Therefore, since it is easy to secure a time during which the voltage change amount ΔV can be acquired, the meter control circuit 40 can stably acquire the voltage change amount ΔV. Therefore, even if the remaining amount of fuel is detected by changing the period tc of the detection signal, the reliability of the operation for detecting the remaining amount is maintained high.

  Further, as in the present embodiment, in the sawtooth detection signal, the time of the proportional range PR in the waveform for one cycle is reliably ensured longer than the time of the return range excluding the proportional range PR. According to the above, since the acquisition of the voltage change amount ΔV by the meter control circuit 40 becomes stable, the certainty of the operation for detecting the remaining amount of fuel is further increased. Therefore, a sawtooth wave detection signal is particularly suitable as the output of the liquid level sensor 20 that changes the period tc according to the height of the liquid level 91.

  Furthermore, in the present embodiment, the predetermined time Δt is set longer than the time of the proportional range PR when the period tc of the detection signal is minimized. Therefore, even when the period tc is minimized, the predetermined time Δt in the proportional range PR of the detection signal is ensured. As described above, the meter control circuit 40 can reliably acquire the voltage change amount ΔV at the predetermined time Δt regardless of the length of the cycle tc of the detection signal. Accordingly, the certainty of detection of the remaining amount by the remaining fuel amount detection system 100 is further improved.

  In addition, in the present embodiment, the signal output unit 35 changes the amplitude Av, which is a change width of the value of the detection signal, according to the length of the period tc of the detection signal. Therefore, compared with the form in which the amplitude of the detection signal is constant regardless of the period tc, in this embodiment, the voltage change amount ΔV when the period tc of the detection signal is increased is further reduced. With the above configuration, since the increase / decrease width of the voltage change amount ΔV that changes in accordance with the liquid level can be expanded, the output from the liquid level sensor 20 is further added to the remaining amount information acquired by the meter control circuit 40. It can be accurately reflected. Therefore, the fuel remaining amount detection system 100 can detect the current remaining amount of fuel with higher accuracy.

  In this embodiment, the meter regulator 50 corresponds to the “power supply” recited in the claims, the meter power supply voltage corresponds to the “power supply voltage” recited in the claims, and the sensor regulator 31 claims. The meter control circuit 40 corresponds to “acquiring means” and “conversion means” described in the claims, and the fuel tank 90 is described in the claims. It corresponds to a “container”, the fuel corresponds to “liquid” described in the claims, and the fuel remaining amount detection system 100 corresponds to “liquid remaining amount detection system” described in the claims.

(Other embodiments)
As mentioned above, although one embodiment by the present invention was described, the present invention is not interpreted limited to the above-mentioned embodiment, and can be applied to various embodiments within the range which does not deviate from the gist.

  In the above embodiment, the meter regulator 50 is not included in the configuration of the remaining fuel amount detection system 100. However, the fuel remaining amount detection system may include a meter regulator. Further, the fuel remaining amount detection system uses the power supplied from the battery as the “power source” instead of the meter power supply voltage generated by the meter regulator, thereby remaining the fuel remaining in the fuel tank 90. May be detected.

  In the above embodiment, the sawtooth detection signal is output from the signal output unit 35. However, the waveform of the detection signal is not limited to the waveform of the above embodiment. The waveform of the detection signal may be triangular, for example, as shown in FIG. In this triangular detection signal, the time in the proportional range PR and the return time excluding the proportional range PR are substantially the same for one period of waveform (see tc in FIG. 6). Further, the proportional range PR in which the voltage change amount ΔV at the predetermined time Δt is acquired may be defined as a proportional range in which the value increases in proportion to the passage of time as shown in FIG. You may prescribe | regulate in the proportional range from which a value decreases in proportion to progress.

  In the embodiment described above, the detection signal is a one-sided waveform in which the value fluctuates only in one direction from the initial value corresponding to the sensor voltage to the maximum amplitude value. However, as long as the detection signal has a waveform including a proportional range, the detection signal may be a double swing waveform in which the value fluctuates on both sides from the initial value. Furthermore, the signal output unit 35 may output the detection signal continuously, or may output an interval portion where the value is constant every cycle or every time a predetermined number of cycles are output. Further, the period tc of the detection signal that has been lengthened as the liquid level becomes lower in the above embodiment may be shortened as the liquid level becomes lower.

  In the above embodiment, the amplitude Av of the detection signal is decreased as the period tc of the detection signal is increased. However, the amplitude of the detection signal may be constant regardless of the period of the detection signal. In this embodiment, the correspondence between the period of the detection signal output from the signal output unit and the voltage change amount acquired by the meter control circuit is easily simplified, so that it is easy to create predefined correspondence information.

  In the above embodiment, the predetermined time Δt for acquiring the voltage change amount ΔV is set to 30 milliseconds. However, the predetermined time Δt may be appropriately changed according to the range in which the period tc of the detection signal output from the signal output unit 35 changes. Specifically, the predetermined time Δt is desirably set to a time slightly shorter than the time in the proportional range when the detection signal cycle is minimized in order to accurately acquire the voltage change amount ΔV. Similarly, the range in which the period tc of the detection signal is changed by the signal output unit 35 may be changed as appropriate.

  In the above embodiment, the detection signal output from the signal output unit 35 is a digital signal having a predetermined resolution and is a voltage output to the power supply line 45. However, the form of the detection signal is not limited to that of the above embodiment. For example, the detection signal may be an analog signal that changes continuously. Further, the detection signal may be a current output to the ground line 46, for example. In this embodiment, the meter control circuit includes a detection circuit that generates a detection voltage based on a detection signal as a current output to the ground line 46 and the meter power supply voltage.

  In the above embodiment, the correspondence information that preliminarily defines the correspondence between the voltage change amount ΔV and the remaining amount information is stored in the microcomputer of the meter control circuit 40 in the form of a data table. However, the form of the correspondence information is not limited to the above embodiment. For example, a function that defines the correlation between the voltage change amount ΔV and the remaining amount information may be stored as correspondence information in a microcomputer or the like.

  In the above embodiment, the microcomputer corresponding to the meter control circuit 40 performs the functions corresponding to the “acquisition means” and “conversion means” described in the claims. However, configurations corresponding to “acquisition means” and “conversion means” are not limited to the meter control circuit of the above embodiment. For example, a meter control circuit constituted by a plurality of microcomputers may fulfill functions corresponding to “acquisition means” and “conversion means”. Or the signal output part which a liquid level sensor has may fulfill a part of function of "acquisition means". Furthermore, an analog circuit that performs the functions of “acquisition means” and “conversion means” without using a program may be used as a meter control circuit instead of the above-described microcomputer.

  In the said embodiment, the liquid level sensor 20 of the form which detects a liquid level height using the float 21 which floats on the liquid was used. However, for example, an ultrasonic liquid level sensor or an optical liquid level sensor may be used as long as it can output a detection signal that includes a proportional range and changes in the cycle tc according to the liquid level. . An ultrasonic or optical liquid level sensor means that the ultrasonic or infrared light emitted toward the liquid level is reflected on the liquid level and the time until the liquid level sensor returns to the liquid level sensor is measured. It is a sensor that detects the surface height.

  Although the present invention has been described based on the example in which the present invention is applied to the fuel remaining amount detection system 100 that detects the remaining amount of fuel stored in the fuel tank 90 of the vehicle, the application target of the present invention is the detection of the remaining amount of fuel. Not limited to. The present invention may be applied to a remaining amount detection system in a container of other liquids mounted on a vehicle, such as brake fluid, engine cooling water, and engine oil. Furthermore, the present invention may be applied not only to the vehicle but also to a system for detecting a remaining amount of liquid in a container provided in various consumer devices and various transport machines.

20 Liquid level sensor, 21 Float, 23 Magnet holder, 24 Float arm, 25 Housing, 31 Sensor regulator (sensor power supply unit), 33 Hall element, 35 Signal output unit, 40 Meter control circuit (acquisition unit, conversion unit), 45 , 47 Power line, 46 Ground line, 50 Meter regulator (power supply), 60 Fuel meter, 80 Combination meter, 90 Fuel tank (container), 91 Liquid level, 100 Fuel level detection system (liquid level detection system), Av Amplitude, tc period, PR proportional range, Δt predetermined time, ΔV Voltage change

Claims (5)

A liquid remaining amount detection system that detects the remaining amount of liquid stored in a container by using power supplied from the power source connected to the power source,
A sensor power supply unit that stabilizes a power supply voltage applied by the power supply, and a proportional range in which the value changes in proportion to the passage of time by applying the sensor voltage stabilized by the sensor power supply unit. A liquid level sensor having a signal output unit that repeatedly outputs a detection signal and changes a cycle of the detection signal according to a liquid level of the liquid;
A detection voltage is generated based on the detection signal output from the signal output unit and the power supply voltage, and a change amount of the detection voltage at a predetermined time set in advance when the detection signal is in the proportional range. Acquisition means for acquiring;
Correspondence information in which the correspondence between the change amount and the remaining amount of the liquid is preliminarily stored is stored, and the current change amount acquired by the acquisition unit is converted into information indicating the remaining amount based on the correspondence information. Conversion means for converting;
A liquid remaining amount detection system comprising:   2. The liquid remaining amount detection system according to claim 1, wherein the detection signal has a time corresponding to the proportional range longer than a time excluding the proportional range per waveform for one period.   The detection signal has a proportional range that changes from an initial value to a maximum amplitude value in proportion to the passage of time, and a return range that returns from the maximum amplitude value to the initial value in a time shorter than the time that is the proportional range. The residual liquid amount detection system according to claim 2, wherein the residual liquid amount detection system has a sawtooth waveform.   The said predetermined time preset in the said acquisition means is shorter than the time of the said proportional range when the period of the said detection signal is made into the minimum, The Claim 1 characterized by the above-mentioned. Liquid remaining amount detection system.   5. The liquid according to claim 1, wherein the signal output unit reduces a change width of a value of the detection signal in the proportional range as the period of the detection signal is increased. Remaining amount detection system.

Images