JP2020121754A - Fuel supply system - Google Patents

Abstract

To detect water contaminated in a fuel (moisture percentage) with high accuracy even when the fuel is discharged at a high rate.SOLUTION: A fuel supply system of this invention comprises: a main pipe 11 that delivers a fuel; a branch pipe 12 that branches off the main pipe 11, delivers the fuel, and has a pipe diameter smaller than that of the main pipe 11; a measurement section that is installed in the branch pipe 12 and measures a moisture percentage of the fuel that flows in the branch pipe 12; a control section that determines presence or absence of abnormality based on the moisture percentage of the fuel measured by the measurement section. Since the moisture percentage is measured by the measurement section in the branch pipe 12 with a small pipe diameter, water contaminated in the fuel can be detected with high accuracy even when the fuel is discharged in the main pipe 11 at a high rate.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fuel supply device for supplying fuel stored in an oil storage tank to a supply target such as a vehicle.

At a gas station, fuel supplied to a vehicle or the like is stored in an oil storage tank installed underground or the like. Fuel is pumped up by a pump or the like and supplied to a vehicle or the like. The oil storage tank is generally installed underground, and therefore water may be mixed with the fuel due to water vapor or condensation in the air. In addition, corrosion or cracks may occur in the oil storage tank or its piping, and ground water or other water may be mixed into the fuel through the corroded portions or cracked portions.

When the fuel mixed with water is supplied to the vehicle, there is a possibility that the engine may be damaged or the engine may stop due to defective combustion. Therefore, it has a function to detect that the water content of the fuel supplied to the vehicle exceeds a predetermined water content, that is, that the fuel contains water, and that the fuel contains water. Fuel supply devices have been developed that are configured to stop the supply of fuel upon detection.

As a method of detecting water in fuel or mixing of different kinds of fuel, there is known a method of measuring characteristics such as capacitance, conductivity, and turbidity of the fuel, and detecting based on the measured values. Here, as a method of measuring the turbidity, there is a method of irradiating the fuel with visible light emitted from an LED or the like. The turbidity can be determined by irradiating a liquid in which fuel and water are mixed and emulsified with visible light, and measuring the light amount of the light transmitted or reflected through the liquid (hereinafter, described as “LED light amount method”). To). For example, Patent Document 1 describes a method for determining whether water or air is mixed in fuel from the amount of transmitted light or the amount of reflected light of LED light.

Since fuel is flammable at a gas station, it is necessary to take explosion-proof measures that require manufacturing costs in a measuring device that detects the mixture of water and the like. In this respect, the LED light amount method described above has an advantage that no explosion-proof measure is required because the electric signal processing board can be installed in the non-explosion-proof area by using an optical fiber.

JP, 2013-237461, A

There are the following problems regarding detection of water content in fuel. More specifically, when supplying fuel to a large-capacity fuel tank mounted on a large vehicle, the fuel is supplied at high discharge (for example, a flow rate of 75 mL/min) in order to shorten the fuel supply time to the fuel tank. Is being done. However, as a result of the study by the present inventors, it has been found that the measurement of the water content under high discharge is more difficult than the measurement of the water content under low discharge. As an example, it has been found that it is difficult to distinguish between the water content at which refueling should be stopped (for example, 5%) and the water content lower than that (for example, 2% or more and less than 5%). If the water content can be detected with high accuracy, measures such as maintenance and inspection can be taken at an early stage by displaying, for example, a message prompting a decision as to whether maintenance or inspection should be performed. However, it is difficult for the existing measuring device to measure the water content of fuel with high accuracy under high discharge.

The present invention has been made in view of the above problems, and is a fuel that can detect water (moisture content) mixed in fuel with high accuracy even when the fuel is supplied with high discharge. An object is to provide a supply device.

A fuel supply device according to a first aspect of the present invention includes a main pipe for feeding a fuel, a branch pipe branched from the main pipe for feeding the fuel, and having a pipe diameter smaller than that of the main pipe. A measurement unit installed in the branch pipe for measuring the water content of the fuel flowing through the branch pipe, and a control unit for determining whether there is an abnormality based on the water content of the fuel measured by the measurement unit.

Further, a fuel supply device according to a second aspect of the present invention is a main pipe for feeding fuel, and a branch having a pipe diameter smaller than that of the main pipe for branching from the main pipe to feed the fuel. A pipe, a measurement unit that measures the water content of the fuel, and a control unit that determines whether there is an abnormality based on the water content of the fuel measured by the measurement unit. The measuring unit includes a light projecting unit that projects light and a light receiving unit that receives the light, and an optical path length between the light projecting unit and the light receiving unit is greater than a pipe diameter of the main pipe. short.

According to the present invention, it is possible to provide a fuel supply device capable of highly accurately detecting water mixed in fuel even under high discharge. Problems, configurations, and effects other than those described above will be clarified by the following description of modes for carrying out the invention.

It is a schematic diagram explaining the fuel supply system concerning a 1st embodiment. It is a flow chart explaining operation of the fuel supply system of a 1st embodiment. It is the schematic explaining the fuel supply apparatus which concerns on 2nd Embodiment. It is a schematic diagram explaining the fuel supply system concerning a 3rd embodiment. It is a schematic diagram explaining the fuel supply system concerning a 4th embodiment. It is a graph which shows the Example of this invention. It is a graph explaining a comparative example.

The present embodiment will be described below with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be represented by the same or corresponding numbers. It should be noted that although the accompanying drawings show embodiments and implementation examples according to the principles of the present disclosure, these are for understanding of the present disclosure, and are used for limiting interpretation of the present disclosure. is not. The descriptions in this specification are merely exemplary, and are not intended to limit the scope of the claims or the application of the present disclosure in any sense.

Although the present embodiment has been described in detail enough for those skilled in the art to carry out the present disclosure, other implementations/forms are also possible without departing from the scope and spirit of the technical idea of the present disclosure. It is necessary to understand that the structure and structure can be changed and various elements can be replaced. Therefore, the following description should not be limited to this. Unless otherwise specified, each component may be plural or singular.

[First Embodiment]
A fuel supply device according to a first embodiment of the present invention will be described with reference to the schematic view of FIG. As an example, this fuel supply device includes a main pipe 11, a branch pipe 12, a light projecting unit 13, a light receiving unit 14, a computing unit 15, a control unit 16, and a display 17 (display unit). It

The main pipe 11 supplies (delivers) the fuel delivered by the pump P from an oil storage tank (not shown) installed underground or the like to a supply destination (fuel tank of a vehicle (not shown)). It is a pipe for. When the supply destination is a vehicle, the fuel may include, but is not limited to, regular gasoline, high-octane gasoline, light oil, and the like. For example, the fuel may contain ethanol. The fuel may be kerosene if the fuel is supplied to other than the vehicle. The fuel passing through the main pipe 11 may be agitated with the air and/or water by being sucked up by the pump P. The material of the main pipe 11 may be a material that does not corrode with fuel such as vinyl chloride.

The branch pipe 12 is configured to branch from a part (first part) of the main pipe 11 and join the main pipe 11 again at a part (second part) on the downstream side of the first part. There is. That is, the branch pipe 12 is connected to the main pipe 11 at least at two positions, that is, the first part and the second part, and after the fuel branched from the main pipe 11 and flowed into the branch pipe 12 flows through the branch pipe 12. , To the main pipe 11 again. The branch pipe 12 has a pipe diameter b smaller (thin) than the pipe diameter a of the main pipe 11. Therefore, the branch pipe 12 can feed the fuel at a speed smaller (slower) than the liquid feed speed of the fuel in the main pipe 11. Like the main pipe 11, the material of the branch pipe 12 may be a material that does not corrode with fuel such as vinyl chloride. However, with respect to the place where the light projecting unit 13 and the light receiving unit 14 are installed, a material such as glass or quartz, which has a high light-transmitting property and can transmit visible light, and which does not hinder the measurement of the light amount may be used. The entire branch tube 12 may be made of a material having high light transmittance. It is preferable that at least a part of the branch pipe 12 is formed so as to extend in a direction substantially parallel to the main pipe 11. By extending in parallel, the space for disposing the branch pipe 12 can be reduced.

The light projecting unit 13 and the light receiving unit 14 are provided at positions facing each other with the branch pipe 12 interposed therebetween. The light projecting unit 13 is composed of, for example, a light emitting diode or the like, and has a function of projecting light having a predetermined optical axis diameter to the light receiving unit 14. When the optical fiber sensor is adopted, the light projecting portion 13 can be the emitting end face of the optical fiber.

The light receiving unit 14 is a light receiving element that measures the amount of light received from the light projecting unit 13 via the branch tube 12. The light receiving unit 14 can be configured by a photodiode or the like. When the optical fiber sensor is adopted, the light receiving unit 14 can be the incident end face of the optical fiber.

The calculator 15 calculates the water content of the fuel in the branch pipe 12 based on the output signal of the light receiver 14. The light projecting unit 13, the light receiving unit 14, and the calculation unit 15 collectively function as a measuring unit that measures the water content of the fuel flowing through the branch pipe 12. The distance L (light path length L) through which the fuel passes between the light projecting unit 13 and the light receiving unit 14 is set to a distance smaller than the pipe diameter a of the main pipe 11 (L<a). As the optical path length L increases, the amount of attenuation of the amount of transmitted light increases and the loss of the amount of received light increases, so the measurement accuracy decreases. Further, when water is mixed in the fuel, the oil of the fuel and the water are mixed with each other, water bubbles adhere to the measurement surface, or the bubbles block light, so that the measurement accuracy decreases. According to the first embodiment, the light projecting portion 13 and the light receiving portion 14 are provided in the branch tube 12 having a small tube diameter, so that the optical path length L can be reduced. As a result, the detection sensitivity of the water content can be increased. For example, in addition to detecting whether the water content of the fuel is 5% or more (second threshold value) that exceeds the safety standard, the safety standard is satisfied, but maintenance or inspection of the device is necessary or recommended. It is also possible to detect whether or not the value is 2% (first threshold value) or more and less than 5%. By enabling such highly accurate detection, it is possible to provide a system that can take measures such as maintenance and inspection of the device at an early stage.

Since the branch pipe 12 has a smaller pipe diameter than the main pipe 11 (b<a), the flow rate of the fuel branched from the main pipe 11 and flowing into the branch pipe 12 is smaller than the flow rate in the main pipe 11, and the flow velocity thereof is also smaller. Is also small. A state in which the flow velocity is low is created in the branch pipe 12, and the water content of the fuel is measured in this portion, so that even if the fuel is supplied at a high flow velocity (high discharge) in the main pipe 11, the water content is highly accurate. Can be measured. If the water content can be measured with high accuracy, it is possible to prevent the supply of fuel having a high water content by displaying a warning that maintenance and inspection are to be performed and performing refueling stop processing as described later. In order to make the flow rate low in the branch pipe 12, the material of the branch pipe 12 may be a material having a large frictional resistance, or the liquid contact surface of the branch pipe 12 may be an uneven surface.

The control unit 16 receives the calculation result of the calculation unit 15 (for example, the water content of the fuel in the branch pipe 12), displays the calculation result on the display 17 in a visible state, and projects the light according to the calculation result. The control of the entire unit 13, the light receiving unit 14, and other fuel supply devices (not shown) may be controlled. The display 17 is configured to be able to display not only information indicating the behavior of the fuel supply device, such as the flow rate of fuel, but also warning information notifying that an abnormality has occurred. The control unit 16 determines whether there is an abnormality based on the water content of the fuel measured by the measurement unit. A specific example of this determination is the determination in step S14 or step S15 in the flowchart of FIG. 2 described later. As an example in which the control unit 16 determines that there is an abnormality, the water content of the fuel may be equal to or higher than a first threshold value (for example, 2%). In this case, the control unit 16 causes the display 17 to display a warning that maintenance and inspection should be performed. Similarly, as an example in which the control unit 16 determines that there is an abnormality, the water content of fuel may be equal to or greater than a second threshold value (for example, 5%). In this case, the control unit 16 stops the fuel supply from the main pipe 11.

The arithmetic unit 15 and/or the control unit 16 may be an electronic circuit including a processor or a memory, and may be configured as one controller or a separate controller (control device). In the following description, information similar to the information displayed on the display 17 (display unit) may be notified from the fuel supply device to the management terminal via the network. This management terminal can be realized by, for example, a computer arranged in an office of a gas station. For example, when the light projecting unit 13 and the light receiving unit 14 are configured by an optical fiber sensor, one end of the optical fiber of the optical fiber sensor is arranged in the branch pipe 12, and the other end is connected to the optical sensor that cooperates with the computing unit 15. To be done. Instead of displaying the warning information on the display 17, it is also possible to send the warning information by voice or the like through a speaker or the like not shown. Further, the calculation unit 15 and/or the control unit 16 may be capable of communicating with a computer (for example, a management terminal) arranged at a physically separated position by a communication device (not shown).

Next, the operation of the fuel supply device according to the first embodiment will be described with reference to the flowchart of FIG.
When the operation of the apparatus is started (START) and the supply of fuel is started via the main pipe 11 and the branch pipe 12, the control unit 16 reads the output signal (light amount) of the light receiving unit 14 (step S11), The calculation unit 15 calculates the light amount of the received light (step S12), and thereby calculates the water content of the fuel (step S13).

In step S14, it is determined whether the water content is less than 2%. If the water content is less than 2% (Yes in step S14), the process returns to step S11, and the refueling is continued while the water content determination based on the output signal of the light receiving unit 14 is continued. On the other hand, if the water content is 2% or more (No in step S14), the process proceeds to step S15.

In step S15, it is determined whether the water content is 2% or more and less than 5%. When the water content is 2% or more and less than 5%, it is within the allowable range for use in the vehicle, but it can be determined that maintenance or inspection is required or recommended in the fuel supply device. Therefore, if the determination in step S15 is affirmative (Yes), an alarm is displayed on the display 17, and in addition to or in place of this, an alarm is issued by, for example, a sound generation device (not shown) (step). S17). Even if the alarm is issued, the water content of the fuel is within the allowable range, so the fuel supply is continued.

On the other hand, when it is determined in step S15 that the water content is 5% or more (No), the control unit 16 immediately executes a process of stopping the pump P to stop the refueling operation (step S16). .. In addition to this, an alarm display indicating that maintenance and inspection should be performed is displayed on the display 17, and in addition to or instead of this, an alarm is issued, for example, by a voice generation device.

Not only the detection of water in the fuel, but also the detection of the mixing of different types of fuel into the target supply fuel to notify the decision to perform maintenance and inspection, and the weighing instrument. It can also be used to display a notification on the terminal screen prompting a decision as to whether maintenance or inspection should be performed.

As described above, according to the fuel supply device of the first embodiment, the water content of fuel is measured in the branch pipe 12 having a smaller pipe diameter than the main pipe 11. Therefore, even if the fuel is supplied with high discharge in the main pipe 11, it is possible to detect the water (moisture content) mixed in the fuel with high accuracy.

[Second Embodiment]
A fuel supply device according to a second embodiment of the present invention will be described with reference to the schematic view of FIG. In FIG. 3, the same components as those in FIG. 1 are designated by the same reference numerals, and therefore duplicated description will be omitted below, and different portions will be mainly described.

The fuel supply system according to the second embodiment also includes a branch pipe 12 having a pipe diameter smaller than that of the main pipe 11, and the branch pipe 12 is provided with a light projecting portion 13 and a light receiving portion 14. However, in the light projecting unit 13 and the light receiving unit 14 of the second embodiment, the detection width (optical axis diameter C) of the light projected and received is made larger than that in the first embodiment. .. As an example, the optical axis diameter C can be set to about 5 mm when the optical path length L is about 10 mm to 50 mm. As an example, it is desirable that the optical axis diameter C be selected such that it is wider than the average diameter of bubbles or the average diameter of water bubbles so that the influence of bubbles or water bubbles can be reduced.

In the method of arranging the light projecting section and the light receiving section facing each other, it is necessary to match the optical axes of the light projecting section and the light receiving section in order to measure the water content of the fuel with high accuracy. Further, when the optical axis diameter is small, the optical axis may be displaced and the measurement accuracy may be reduced. In particular, when fuel is supplied at a high discharge, the vibration of the pump increases and the piping in which the light projecting unit is installed also vibrates, so the optical axis is more likely to shift and the probability of incorrect measurement increases. .. When the optical axis diameter C of the light projecting unit 13 and the light receiving unit 14 is small, misalignment of the optical axis causes erroneous measurement, so that the optical axis diameter C is preferably long.

[Third Embodiment]
A fuel supply device according to a third embodiment of the present invention will be described with reference to the schematic diagram of FIG. In FIG. 4, the same components as those in FIG. 1 are designated by the same reference numerals, and therefore, duplicate description will be omitted below, and different portions will be mainly described.

The fuel supply system according to the third embodiment includes the branch pipe 12 similar to that of the first embodiment. The light projecting unit 13 and the light receiving unit 14 are arranged in the branch pipe 12 as in the first embodiment. In addition to this, in the fuel supply device of the third embodiment, in the upstream side of the position where the light projecting unit 13 and the light receiving unit 14 are installed, for example, in the branch portion (first portion) of the branch pipe 12, It has a filter 18 for removing air bubbles and water bubbles. According to the device of the third embodiment, the same effect as that of the first embodiment can be obtained. In addition, since the filter 18 is provided, it is possible to prevent the bubbles and water bubbles from adhering to the emission end surface of the light projecting portion 13 and the light receiving end surface of the light receiving portion 14 for bubbles and water bubbles, and to include the fuel with higher accuracy. It becomes possible to measure the amount of water.

The material of the filter 18 may be polytetrafluoroethylene (PTFE), which does not deteriorate due to contact with fuel, or polyvinylidene fluoride (PVDF). However, the material is not limited to these, and any material having a function of removing water bubbles and bubbles to a certain extent may be used. The surface of the filter 18 is preferably hydrophobic so that the fuel can easily pass therethrough.

[Fourth Embodiment]
A fuel supply device according to a fourth embodiment of the present invention will be described with reference to the schematic view of FIG. 5, since the same components as those in FIG. 1 are designated by the same reference numerals, duplicate description will be omitted and different portions will be mainly described.

The fuel supply system of the fourth embodiment includes the branch pipe 12 similar to that of the first embodiment. However, unlike the above-described embodiment, the light projecting unit 13 and the light receiving unit 14 are arranged not in the branch pipe 12 but in the main pipe 11. The optical path length L between the light projecting unit 13 and the light receiving unit 14 is set smaller than the pipe diameter a of the main pipe 11. Therefore, the flow velocity of the fuel flowing between the light projecting unit 13 and the light receiving unit 14 is suppressed as compared with the main flow portion of the fuel in the main pipe 11, and the same effect as that of the above-described embodiment can be obtained. In addition, the light projecting surface L1 of the light projecting portion 13 and the light receiving surface L2 of the light receiving portion 14 are both flat surfaces and are arranged in parallel with each other. Since the light projecting surface L1 and the light receiving surface L2 are planes parallel to each other, light travels in a straight line and travels, and refraction/scattering can be suppressed. Therefore, higher measurement accuracy can be ensured.

[Example]
Hereinafter, an example of measuring the water content of the fuel containing water in the fuel supply device according to the embodiment of the present invention will be described.

<Example 1>
In Example 1, tap water was added to light oil so that the water content was 0%, 1%, and 5%, and then the light oil and tap water were stirred to form an emulsion. The measurement result when supplied to the fuel supply device of the embodiment is shown. When the emulsion passed between the light projecting section 13 and the light receiving section 14 which compose the optical fiber sensor, the amount of light passing through the emulsion and detected by the light receiving section 14 was measured. The optical path length L was changed to 10 mm, 20 mm, and 50 mm, and the optical axis diameter C was set to 5 mm. The distance between the light projecting unit 13 and the light receiving unit 14 was 100 mm.

When the optical path length L was shortened to 10 mm and the water content was changed to 0%, 1%, and 5%, the change in the light amount (intensity) of the received light was as shown by the curve α in FIG. Further, when the optical path length L is slightly lengthened to 20 mm and the water content is changed to 0%, 1%, and 5%, the change in the light amount (intensity) of the received light is as shown by the curve β in FIG. It was Further, when the optical path length L is increased to 50 mm and the water content is changed to 0%, 1%, and 5%, the change in the light amount (intensity) of the received light is as shown by the curve γ in FIG. .. The curves α and β can detect the difference between the water contents of 1% and 5%. Further, comparing the optical path lengths L=10 mm and 20 mm, it can be seen that the optical path length of 10 mm has a large difference in the light amount of the received light at the water contents of 1% and 5% and can be accurately measured.

<Example 2>
In Example 2, tap water was added to light oil so that the water content was 0%, 1%, and 5%, and then light oil and tap water were stirred to obtain an emulsion, which was produced from the pump P. The measurement result at the time of supplying to the fuel supply device of the first embodiment is shown. When the emulsion passed between the light projecting section 13 and the light receiving section 14 which compose the optical fiber sensor, the amount of light passing through the emulsion and detected by the light receiving section 14 was measured. The optical path length L was set to 10 mm and the optical axis diameter C was set to 5 mm. The distance between the light projecting unit 13 and the light receiving unit 14 was 10 mm. Further, a measurement window made of a transparent material was installed in the branch pipe 12, and further, the light projecting unit 13 and the light receiving unit 14 were installed so that the optical path length L was shorter than the pipe diameter a of the main pipe 11. The measurement window was made of transparent glass. Under this configuration and conditions, although not shown, it was found that the difference in the light amount between the water contents of 1% and 5% can be determined.

<Example 3>
In Example 3, tap water was added to light oil so that the water content was 0%, 1%, and 5%, and then an emulsion formed by stirring the light oil and tap water was prepared. The measurement result at the time of supplying to the fuel supply system of a 4th embodiment is shown. When the emulsion passed between the light projecting section 13 and the light receiving section 14 which compose the optical fiber sensor, the amount of light passing through the emulsion and detected by the light receiving section 14 was measured. The optical path length L was set to 10 mm and the optical axis diameter C was set to 5 mm. The distance between the light projecting unit 13 and the light receiving unit 14 was 10 mm. Further, a measurement window made of a transparent material was installed in the branch pipe 12, and further, the light projecting unit 13 and the light receiving unit 14 were installed so that the optical path length L was shorter than the pipe diameter a of the main pipe 11. The measurement window was made of transparent glass. Further, a filter 18 for removing air bubbles and water bubbles is installed at a connection point where fuel flows from the main pipe 11 into the branch pipe 12. Although not shown in the drawing, it was found that the difference in the light amount between the water content of 1% and the light amount of 5% can be determined even with this configuration and conditions.

<Comparative example>
In the comparative example, in the apparatus of the first embodiment, the conditions are set in the same manner as in Example 1, but the optical axis diameter C is reduced to 1.13 mm. The measurement result in this case is shown in FIG. As indicated by a symbol D in FIG. 7, when the water content is 0%, the amount of light varies depending on the optical path length L, and regardless of the size of the optical path length L, the water content is 1% and the water content is 5%. It was found that there was no difference in the amount of received light and it was difficult to determine the water content with high accuracy. It is considered that this is because the optical axis diameter C is as small as 1.13 mm and the optical axes of the light projecting unit 13 and the light receiving unit 14 are deviated from each other, resulting in a decrease in measurement accuracy. Therefore, it is preferable to set the optical axis diameter C to a sufficient size in relation to the optical path length L.

Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

Claims (9)

Main piping for sending fuel,
A branch pipe having a pipe diameter smaller than that of the main pipe, branching from the main pipe to feed the fuel.
A measuring unit installed in the branch pipe for measuring the water content of the fuel flowing through the branch pipe,
A control unit that determines whether there is an abnormality based on the water content of the fuel measured by the measurement unit,
A fuel supply device comprising: Further comprising a display unit for displaying information including the water content,
The control unit is configured to cause the display unit to display an alarm to the effect that maintenance should be performed when the water content is equal to or higher than a first threshold value.
The fuel supply device according to claim 1. The fuel supply device according to claim 1, wherein the control unit stops the liquid supply of the fuel from the main pipe when the water content is equal to or higher than a second threshold value. The fuel supply device according to claim 1, wherein at least a part of the branch pipe is substantially parallel to the main pipe. The branch pipe is connected to the main pipe at least at two points,
The fuel supply device according to claim 1, wherein the branch pipe is configured so that the fuel flowing from the main pipe to the branch pipe flows to the main pipe after flowing through the branch pipe. The fuel supply device according to claim 1, further comprising a filter arranged upstream of the measuring unit to remove air bubbles or water bubbles. The measuring unit includes a light projecting unit that projects light, and a light receiving unit that receives the light,
The optical path length between the light projecting unit and the light receiving unit is shorter than the pipe diameter of the main pipe,
The fuel supply device according to claim 1. Main piping for sending fuel,
A branch pipe having a pipe diameter smaller than that of the main pipe, branching from the main pipe to feed the fuel.
A measuring unit for measuring the water content of the fuel,
A control unit that determines whether there is an abnormality based on the water content of the fuel measured by the measurement unit,
Equipped with
The measuring unit includes a light projecting unit that projects light, and a light receiving unit that receives the light,
An optical path length between the light projecting portion and the light receiving portion is shorter than a pipe diameter of the main pipe. The fuel supply device according to claim 8, wherein the light projecting surface of the light projecting portion and the light receiving surface of the light receiving portion are planes parallel to each other.

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