JP5765637B2 - Foreign matter detection device - Google Patents

Description

The present invention relates to a fueling device used in a filling station that supplies fuel oil (oil) to a vehicle or the like. More specifically, the present invention relates to a technique for detecting that foreign matters such as water are mixed in fuel oil in such a fueling device.

In a gas station, fuel oil such as gasoline stored in an underground tank of the gas station is supplied to a vehicle or the like by a fueling device.
Water may enter the fuel oil due to external factors such as damage to underground tanks, human factors such as erroneous operations, and factors such as accidents and natural disasters. If water is mixed into the fuel oil due to various factors like this, gasoline containing water will be supplied to the vehicle, causing the engine to be unable to start, and causing knocking due to poor combustion, In the worst case, there is a problem that the engine is damaged due to frequent knocking.

In order to cope with such a problem, it is conceivable to detect the property of the liquid by utilizing the property that the capacitance is different for each type of liquid.
Here, the capacitance C is C = (ε0 · εs · S) / d (where S is the area of the electrode, ε0 is the dielectric constant of the vacuum, εs is the dielectric constant of the dielectric, and d is the distance between the electrodes) It can be obtained by the following formula.
Since the influence of the disturbance can be reduced as the electrostatic capacitance C is larger, it is effective for detecting the property of the liquid.

In order to measure the capacitance and detect whether water or other foreign matter is mixed in the fuel oil, a pair of plate-like electrodes are placed in parallel to the fuel oil flow in the fuel oil supply system. It is necessary to dispose the fuel oil between the pair of plate electrodes. As described above, the larger the capacitance of the pair of plate electrodes, the better.
However, when the area of the plate electrode is increased, it is difficult to install the fuel electrode in the fuel oil supply system (supplying equipment such as piping and pump units) in the fueling device.
Further, if the interval between the plate electrodes is reduced, the fluid resistance in the region between the pair of plate electrodes is increased, and dust and other foreign matters are liable to stay, which is disadvantageous.

As another conventional technique, a technique has been proposed in which a voltage corresponding to the relative dielectric constant of alcohol-mixed gasoline is detected to detect a change in gasoline properties (see, for example, Patent Document 1).
However, in the related art, a metal box-shaped casing is necessary, and a space for installing the casing must be secured, and it is difficult to install the casing inside the fuel oil supply system in the fueling device. is there.

Japanese Patent Laid-Open No. 5-288707

The present invention has been proposed in view of the above-described problems of the prior art, and can be installed inside a fuel oil supply system to detect that foreign matters such as water are mixed in the fuel oil. The purpose is to provide a refueling device that can be used.

According to the present invention, the fuel supply unit (3) is provided in the middle of the pipes (4, 5) from the underground tank (1) for storing fuel oil to the fuel hose connection part in the fuel supply mechanism (2), and the pipe (4 5) In the foreign matter contamination detection device of the fueling device provided with a capacitance type water detection sensor (10A) for detecting that foreign matter is mixed in the fuel oil in either the fuel supply unit (3). The capacitance type water detection sensor (10A) includes a first cylindrical mesh electrode (121A) provided radially outward at one end of a ring-shaped member (11A) and the first cylinder. A second cylindrical mesh electrode (122A) provided radially inward of the mesh mesh electrode (121A) is concentrically spaced and fixed, and the first and second mesh electrodes ( 121A, 122A) is the stray of the pump (3P) of the fueling device The ring-shaped member (11A) side is opened as the opening portion side of the strainer (31), and is opposite to the ring-shaped member (11A). Is closed by the closing member (32), and the fuel oil (F) entering from the opening of the strainer (31) flows outward in the radial direction to cause the second mesh electrode (122A) and the first mesh electrode (121A). And flow out radially outward of the strainer (31).
Here, it is preferable that the water detection sensor (10A) can detect not only water but also other foreign matters.

In the present invention, it is preferable that the mesh electrodes (121A, 122A) include not only a case of so-called “mesh” but also a shape having a large number of through holes.

Moreover, in this invention, it is preferable that the mesh electrode (one or both) is insulated.
For insulation, for example, it is preferable to coat the mesh electrode (121A, 122A) with an insulating material.

Furthermore, in the present invention, the sensor (10A) preferably has an uninsulated mesh electrode and an insulated mesh electrode.
In this case, it is preferable to dispose an uninsulated electrode between the uninsulated mesh electrode and the insulated mesh electrode.

According to the present invention having the above-described configuration, the capacitance type water detection sensor (10A) is provided in either the pipe ( 4 , 5) or the oil supply unit ( 3 ). When water (or other foreign matter) is mixed in, it can be immediately detected by a change in capacitance or dielectric constant.
For this reason, it is possible to prevent the gasoline containing water from being supplied to the vehicle, and to prevent the engine from starting, the occurrence of knocking due to poor combustion, and the engine from being damaged.

Here, since the sensor (10A) is composed of the mesh electrodes (121A, 122A), the mesh electrodes (121A, 122A) are arranged in a direction perpendicular to the flow path (or the flow line F of the fuel oil). Even if it arrange | positions, fuel oil can pass through a mesh-like electrode (121A, 122A) without resistance.
And even if the interval between the mesh electrodes (121A, 122A) is narrowed, the resistance does not increase, and the capacitance can be increased to reduce the influence of noise.

In addition, according to the present invention, the mesh electrodes (121A, 122A) can be attached to the outside of the strainer (31), so that the space for the sensor (10A) can be saved.
Since the mesh electrodes (121A, 122A) are formed in a hollow cylindrical shape with one opening, the electrode area is increased compared to the plate-shaped mesh electrode (12), and the capacitance is increased. It can be enlarged.

Furthermore, if the mesh electrode (one or both) is insulated (if two mesh electrodes having different characteristics are used), a short circuit current (leakage current) is prevented from flowing through the fuel oil flowing between the electrodes. By cutting the leakage current, it is possible to reliably detect only the change in capacitance with high accuracy.
And it is also prevented that the sensitivity of the sensor (10A) increases too much due to the leakage current.

It is explanatory drawing which shows the oil supply apparatus which concerns on the reference example of this invention. It is a side view which shows the sensor which comprises the principal part of the reference example of this invention. It is a perspective view of the sensor of FIG. It is the A section enlarged view of FIG. It is a conceptual diagram which shows the general capacitor | condenser using a plate-shaped electrode. It is explanatory drawing for demonstrating the inconvenience of the capacitor | condenser of FIG. It is a conceptual diagram of the sensor of FIG. It is explanatory drawing for demonstrating the merit of the sensor of FIG. It is a perspective view which shows the sensor which comprises the principal part of embodiment of this invention. It is explanatory drawing which shows the XX cross section in the sensor of FIG. FIG. 10 is a perspective view of a pump strainer in which the sensor of FIG. 9 is arranged. It is a perspective view which shows the state which covered the sensor of FIG. 9 on the pump strainer of FIG. It is explanatory drawing which shows the XX cross section of FIG. It is a perspective view of the oil supply pump which covers the sensor of FIG. It is a characteristic view which shows an example of the relationship between the hydrolysis rate to ethanol, and an electrostatic capacitance. It is a conceptual diagram explaining the leakage current of the sensor used by embodiment of this invention. It is a conceptual diagram explaining the effect | action of a sensor. It is explanatory drawing which shows the influence of the frequency of an electric current, and leakage current with a chart. It is a characteristic view which shows the relationship between the ratio of the ethanol included in gasoline, and an electrostatic capacitance.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 to 8 show reference examples of the present invention.
First, referring to FIG. 1, an outline of a fueling device to which a reference example of the present invention is applied is shown.
In FIG. 1, an oil supply apparatus denoted by reference numeral 100 as a whole is a unit 3 (an oil supply unit 3) comprising an underground tank 1, an oil supply mechanism 2, an oil supply pump, and a flow meter buried underground in a gas station (gasoline station or the like). ), Underground buried pipe 4, oil supply mechanism internal pipe 5, oil supply hose 6, and oil supply nozzle 7.

The oil supply unit 3 and the oil supply mechanism internal pipe 5 are provided in the oil supply mechanism 2, and the underground buried pipe 4 connects the underground tank 1 and the oil supply unit 3.
The oil supply mechanism internal pipe 5 connects the oil supply unit 3 and the oil supply hose 6. An oil supply nozzle 7 is provided at the tip of the oil supply hose 6.
Although not clearly shown, the oil supply nozzle 7 is locked to a nozzle hook (not shown) provided on the outer peripheral panel of the oil supply mechanism 2.
A foreign matter contamination detection apparatus (hereinafter referred to as “sensor”) 10 according to a reference example of the present invention is schematically shown in FIG. In FIG. 1, the sensor 10 (see FIG. 2) is interposed in any of the underground buried pipe 4, the oil supply unit 3, and the oil supply mechanism internal pipe 5.
And the sensor 10 can detect that water mixes by the change of an electrostatic capacitance. This is because the dielectric constant of fuel oil and water is greatly different, and the capacitance changes greatly even if a small amount of water is mixed into the fuel oil.

Here, since the dielectric constant of the fuel oil mixed with foreign matter is the sum of the dielectric constant of the fuel oil and the dielectric constant of the foreign matter, the presence or absence of foreign matter can be accurately detected even if the fuel oil and the foreign matter are not evenly mixed. Can be detected.
Therefore, the fuel oil is located in the underground tank 1 side of the rotating body (not shown) in the pump of the refueling unit 3, in other words, in the underground tank 1 side of the area where the fuel oil is uniformly mixed by the rotating body. Even in such a case, when foreign matter (water in the illustrated embodiment) is mixed in the fuel oil, the fact and the mixing rate can be accurately determined.

A sensor 10 according to a reference example of the present invention will be described with reference to FIGS.
2 to 4, the sensor 10 includes an annular frame 11, a pair of mesh electrodes 12, a capacitance calculation device 13, and a pair of cables 14. The edge of the mesh electrode 12 is supported by a frame 11 for making the interval constant. Although not shown, a spacer for making the interval constant may be disposed between the mesh electrodes 12 and 12.
As shown in FIG. 4, the cross-sectional shape of the annular frame 11 is convex, and the convex protrusion 11t faces inward in the radial direction (of the ring).
The pair of mesh electrodes 12 are disposed in contact with both side portions 11 s and the step portions 11 a of the projecting protrusion portion 11 t of the frame body 11.
Here, the term “mesh” is used to include not only a shape having a so-called “mesh” but also a shape having a large number of through holes.

If the area of the mesh electrode 12 is S, the dielectric constant of vacuum is ε0, the dielectric constant of the dielectric (mesh electrode 12) is εs, and the distance between the electrodes is d,
The capacitance C is obtained by the following formula: C = (ε0 · εs · S) / d
Here, since the influence of disturbance can be reduced as the capacitance C increases, it is effective for detecting the properties of the liquid.
The upper limit of the diameter D of the frame 11 in the sensor 10 is determined by the inner diameter of the underground buried pipe 4 if the installation location is, for example, in the underground buried pipe 4 (see FIG. 1). Therefore, in order to obtain a large capacitance C in the pair of mesh electrodes 12, the distance d between the pair of mesh electrodes 12 may be set small.
2 to 4, even if the distance d between the mesh electrodes 12 is set to a small value, the fuel oil can be easily added to the mesh electrode 11 because the electrodes are mesh. You can go through the mesh. Therefore, with the mesh electrode 12 of FIGS. 2 to 4, the passage resistance when the fuel oil as the detection target passes through the electrode 12 does not increase.

FIG. 5 shows a capacitor 10J having a general configuration constituted by a plate-shaped electrode (plate electrode) 12P without using the mesh electrode 12 of FIGS. In the general capacitor 10J in FIG. 5, electrification accumulates between the electrodes 12P, and an electric field is formed.
Here, when the capacitor 10J using the general plate electrode 12P as shown in FIG. 5 is arranged in the fuel oil supply pipe, as shown in FIG. It must be arranged in parallel to the streamline F in the supply pipe. This is because if the plate electrode 12P is arranged in a direction orthogonal to the flow line F of the fuel oil supply pipe, the plate electrode 12P blocks the flow of the fuel oil.

As described above, in the capacitor 10J, the influence of the disturbance can be reduced as the capacitance increases, which is effective for detecting the property of the liquid from the capacitance.
However, if the area of the plate-like electrode 12P of the capacitor 10J is increased, it becomes difficult to install the capacitor J inside the fuel oil supply system (supplying equipment such as a pipe and a pump unit) in the fueling device.
On the other hand, if the distance d between the plate-like electrodes 12P is reduced, the fluid resistance in the region between the pair of plate-like electrodes 12P is increased, and dust and other foreign matters are liable to stay.

Here, since the capacitance C between the electrodes 12 is determined by the atmosphere of the electric field, as shown in FIG. 7, even if the electrodes 12 are configured by a net, charges similar to those of the plate-like electrodes are stored. The That is, if it is the sensor 10 of the reference example of this invention shown in FIGS. 2-4, the electrostatic capacitance similar to the capacitor | condenser 10J using the conventional plate-shaped electrode 12P will be obtained.
In the case of the sensor 10 of the reference example of the present invention shown in FIGS. 2 to 4, as shown in FIG. 8, the mesh electrode 12 may be arranged in a direction perpendicular to the flow line F of the fuel oil in the supply pipe. Since the fuel oil can easily pass through the “mesh” (or many through holes) of the mesh electrode 12, the sensor 10 of FIGS. Even if it is arranged in a direction perpendicular to F, the flow of fuel oil is not hindered.
Furthermore, since the fuel oil can pass through the “mesh” (or a large number of through holes) of the mesh electrode 12 without resistance, the fuel oil can be obtained even if the distance d between the pair of mesh electrodes 12 is narrowed. The flow resistance does not increase. In other words, in the sensor 10 of the reference example of the present invention shown in FIGS. 2 to 4, the gap between the pair of mesh electrodes is reduced without increasing the resistance of the flow of fuel oil, and the static electricity between the electrodes is reduced. Capacitance can be increased.
Thereby, if it is the sensor 10 which concerns on the reference example of this invention shown in FIGS. 2-4, while increasing an electrostatic capacitance and making the influence of a disturbance small, it will not disturb the flow of fuel oil, but the The dielectric constant can be detected accurately and effectively.

Next, a sensor 10A according to an embodiment of the present invention will be described with reference to FIGS.
The sensor 10A shown in FIGS. 9 and 10 is configured to be used by being placed on the strainer 31 of the pump 3P shown in FIG. 14 (see FIG. 11 for the strainer 31 alone). Here, the pump 3P is included in the oil supply unit 3 shown in FIG.
9, the sensor 10A has one end in the ring member 11A (the right end in FIG. 9), as shown in Figure 10, mesh electrodes 121A (radially outward of the electrodes), 122A (radial Inner electrodes) are fixed concentrically at a predetermined interval. This sensor 10A is used by being put on a strainer 31 shown in FIG.
An arrow F in FIG. 11 indicates the flow of the fuel oil that flows into and out of the strainer 31.

In the sensor 10A, the right end side in FIGS. 9 and 11 is closed by the closing member 32 as shown in FIG.
As shown in FIG. 12, the fuel oil F that has entered from the opening of the strainer 31 (the left end in FIG. 12) flows outward in the radial direction of the strainer 31 as shown in FIG. It flows out radially outward of the strainer 31 via the electrode 121A.

As described in the reference example of the present invention with reference to FIGS. 2 to 8, according to the sensor 10 </ b> A described with reference to FIGS. 9 to 14, the foreign matters contained in the fuel oil are uniformly mixed. Even in the region upstream of the position (underground tank 1 side of FIG. 1), that is, the region upstream of the pump rotating body (underground tank 1 side of FIG. 1), is water mixed, for example? It is possible to accurately determine whether or not.
Therefore, the sensor 10A according to the illustrated embodiment can be disposed on the strainer 31 (FIG. 14), which is a member located on the upstream side of the pump rotor.

As apparent from FIG. 13, the metal mesh member constituting the strainer 31 does not constitute the mesh electrode in the sensor 10A used in the embodiment of the present invention.
The strainer 31 is configured to have a small mesh so as to capture foreign matter and filter the fuel oil. Therefore, the resistance against the flow of the fuel oil is large, and there is a possibility that the fuel oil moves in the streamline direction. When one mesh member in the sensor 10A used in the embodiment of the present invention is constituted by the mesh member of the strainer 31, when the strainer 31 moves in the flow direction of the fuel oil, the interval between the mesh members, that is, the electrode interval. Fluctuates and the capacitance changes. For this reason, the calculation result of the dielectric constant of the liquid flowing through the strainer 31 fluctuates, so that the presence / absence of water mixing and the mixing rate cannot be accurately determined.
Therefore, the metal mesh member constituting the strainer 31 does not constitute a mesh electrode in the sensor 10A.

The sensor 10A shown in FIGS. 9 and 10 can increase the capacitance by increasing the area of the electrode as compared with the sensor 10 shown in FIGS.
Further, by placing the sensor 10A shown in FIGS. 9 and 10 on the pump strainer 31 shown in FIG. 11, the installation space for the sensor 10A can be secured, and the restriction on the layout of the oil supply mechanism 2 can be reduced accordingly. .
Such a sensor 10A can provide an intrinsically safe explosion-proof structure (main safety structure).

Other configurations and operational effects of the embodiment of the present invention described with reference to FIGS. 9 to 14 are the same as those of the reference example of the present invention of FIGS.

FIG. 15 is a characteristic diagram showing the relationship between the hydrolysis rate to ethanol and the capacitance.
As shown in FIG. 15, the alcohol product such as ethanol is also mixed with water in the illustrated embodiment (the reference example of the present invention in FIGS. 1 to 8 and the embodiment in FIGS. 9 to 14). It can be detected effectively.
As in the case of gasoline (dielectric constant of about 2) and water (dielectric constant 80), the dielectric constants of ethanol (dielectric constant around 20) and water (dielectric constant 80) are also very different. This is because the capacitance also changes greatly.

In FIG. 15, which shows the relationship between the water addition rate to ethanol and the capacitance, the increase in capacitance is notable until the water addition rate to ethanol becomes 0.5 or more.
However, even if the amount of water added (hydrolysis ratio) is 0.5 mol or less, if the sensitivity of the sensor (sensitivity for detecting the difference in capacitance) is increased, that water is mixed in ethanol and its It is possible to detect the mixing rate (hydrolysis rate).

Although not shown, for the sensor 10A according to the embodiment of the present invention shown in FIGS. 9 to 13, the hollow cylindrical electrodes 121A and 122A made of a mesh member are covered with an insulator, and the fuel oil It is possible to block leakage current due to conductivity and prevent erroneous detection due to increase in sensor sensitivity due to leakage current.
In that case, both of the mesh electrodes 121A and 122A can be covered with an insulating material, or only one of them may be covered with an insulating material.
This is because no leakage current flows between the mesh electrodes even if both of the pair of mesh electrodes are covered with an insulating material or only one of the mesh electrodes is covered with an insulating material.

The reason why the mesh electrodes 121A and 122A are covered with an insulating material in the sensor 10A will be described with reference to FIGS.
Water has a property of becoming a conductor when impurities are mixed therein. Generally, the capacitance is measured by passing a current through water mixed with impurities and measuring the time during which the voltage between terminals rises (or falls). In this case (water becomes a conductor due to impurities), a short-circuit current flows between the electrodes, and the time until electrification is accumulated becomes longer, and it seems as if the capacitance has increased.
FIG. 16A schematically shows a state where no conductor exists between the electrodes 12 and no short-circuit current flows. The capacitance is measured by passing a current between the electrodes 12 in the state of FIG. 16A and measuring the time during which the voltage between the terminals rises (falls).

Here, fuel oil (including fuel oil mixed with water) is a conductor.
When a liquid having conductivity exists between the pair of electrodes 12, the electrodes 12 are short-circuited by the fuel oil, that is, the conductive liquid, and a short-circuit current (leakage current) flows as shown in FIG.
When the short-circuit current flows, the apparent capacitance increases (it appears as if the capacitance has increased). In other words, when the short-circuit current flows, the apparent change amount of the capacitance becomes larger than the change amount of the capacitance between the electrodes.
And since the amount of change in the apparent capacitance increases, the change in capacitance when water is mixed into the fuel oil also increases, and the sensitivity as a sensor increases.

However, there is a possibility that erroneous detection occurs due to an increase in sensitivity of the sensor. For example, even if the sensitivity of the sensor is increased and a change in capacitance is detected, the change in capacitance is “a change in capacitance due to the mixing of water?” It is impossible to distinguish between “changes” and “changes in capacitance due to other factors”. As a result, although it is “a change in capacitance due to a temperature change”, a situation may be erroneously determined as “a change in capacitance due to mixing of water”.
On the other hand, if the mesh electrodes 121A and 122A are covered with an insulator to block the leakage current due to the conductivity of the fuel oil, and the state shown in FIG. 17 is obtained, the leakage current is generated between the mesh electrodes 121A and 122A. Since it does not flow, the apparent capacitance change amount does not become too large. Therefore, the sensitivity of the sensor does not become too good, and the above-described erroneous detection is prevented.

Next, with reference to FIG. 18, the cycle of charging and discharging between a pair of electrodes will be described.
In the illustrated embodiment (the reference example of the present invention in FIGS. 1 to 8 and the embodiment in FIGS. 9 to 14), the measurement frequency of the water and foreign matter detection circuit in the sensor is increased (charging between a pair of electrodes) By shortening the discharge cycle), the leakage current can be reduced and the influence of the leakage current can be reduced.

The current is proportional to the voltage, and there is no difference in the ratio between the accumulated current and the leakage current between the pair of electrodes even if the charging and discharging cycles vary.
However, as shown in FIG. 18, if the measurement frequency of the detection circuit is increased, the time during which the leakage current flows is shortened, so the total amount of leakage current is reduced (FIG. 18B), and conversely the measurement of the detection circuit. If the frequency is slowed down, the leakage current flows for a long time, and the total amount of leakage current increases (FIG. 18A).
There is an appropriate discharge and charge cycle (measurement frequency of the contamination detection circuit) corresponding to the detection target (type of fuel oil and type of foreign matter) and the purpose of detection, so the appropriate cycle (frequency) is the case.・ By determining on a case-by-case basis, the detection can be performed with higher accuracy and meeting the purpose.
18A and 18B, “leakage” means leakage current, “charging” means charging current between the electrodes, and “discharging” means discharging current from between the electrodes.

FIG. 19 shows the relationship between the ratio of gasoline to alcohol (ethanol ratio) and the capacitance in alcohol fuel.
Alcohol-mixed gasoline, which is a mixed fuel, is known. As the alcohol mixed gasoline, for example, E3 (containing 3% ethanol), E5 (containing 5% ethanol), E10 (containing 10% ethanol), and the like are used. In addition, E23 (containing 23% ethanol), E85 (containing 85% ethanol), and the like are also used overseas.
Since gasoline and ethanol have different dielectric constants by an order of magnitude, the ethanol ratio can be calculated by applying the illustrated embodiment. As a result, a situation (so-called “contamination”) in which different types of fuel are erroneously mixed can be prevented.

The capacitance due to the difference in the ratio of ethanol contained in regular gasoline has a proportional relationship as shown in FIG. Therefore, the ethanol ratio (%) contained in the regular gasoline can be known by measuring the capacitance.
However, since the capacitance has temperature dependence, it is necessary to correct it together with the temperature sensor in order to know the absolute value (ethanol ratio).
In FIG. 25, the solid line is a capacitance in which the arrangement of the pair of mesh electrodes in the sensor is arranged in parallel with the direction of fuel flow, and the broken line is the arrangement of the pair of mesh electrodes in the direction of fuel flow. In contrast, the capacitance is arranged in series.

It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Underground tank 2 ... Oil supply mechanism 3 ... Unit for oil supply 4 ... Underground piping 5 ... Pipe in oil supply mechanism 6 ... Oil supply hose 7 ... Oil supply nozzle 10 ... Water detection sensor 11... Frame 12... Mesh electrode 13.

Claims (1)

An oil supply unit (3) is provided in the middle of the pipe (4, 5) from the underground tank (1) for storing fuel oil to the oil supply hose connection in the oil supply mechanism (2), and the pipe (4, 5) or for oil supply In the foreign matter contamination detection device of a fueling device provided with a capacitance type water detection sensor (10A) for detecting that foreign matter is mixed in fuel oil in any of the units (3), the capacitance type The water detection sensor (10A) includes a first cylindrical mesh electrode (121A) provided radially outward at one end of the ring-shaped member (11A) and the first cylindrical mesh electrode (121A). ) In the radial direction, the second cylindrical mesh electrode (122A) is concentrically spaced and fixed, and the first and second mesh electrodes (121A, 122A) are oiled. Outside the strainer (31) of the pump (3P) of the device The ring-shaped member (11A) side is opened as the opening side of the strainer (31), and the opposite side of the ring-shaped member (11A) is the blocking member (32). The fuel oil (F) that is blocked by the flow and enters from the opening of the strainer (31) flows outward in the radial direction and passes through the second mesh electrode (122A) and the first mesh electrode (121A) to form the strainer. (31) A foreign matter contamination detection device that flows outward in the radial direction.

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