CN108240851B - Liquid level state detection device and fuel cell system - Google Patents

Abstract

The present invention provides a liquid surface state detection device capable of measuring the liquid surface height in a tank and detecting the inclination of the tank, and a fuel cell system including the liquid surface state detection device. The liquid surface state detection device (10) is provided with: a float part (20) capable of moving in an up-down direction guided by a guide rod (45) erected in a liquid storage tank (1) in which liquid (2) is stored; and a pair of electrode portions (30), which are integrally fixed to the float portion (20) and are disposed opposite to each other in the up-down direction, wherein the And the electrostatic capacitance between a pair of electrode parts (30) which changes, detects the liquid level height in the liquid storage tank (1) and the inclination of the liquid storage tank (1).

Description

Liquid level state detection device and fuel cell system

technical field

The present invention relates to a liquid level state detection device and a fuel cell system including the liquid level state detection device.

Background technique

In recent years, the use of fuel cells that take in hydrogen and oxygen in the air to generate electric energy through chemical reactions has been progressing in cogeneration systems, fuel cell vehicles, and the like. For example, in a gas cogeneration system, hydrogen to be supplied to a fuel cell is generated from natural gas and reformed water by a steam reforming method, etc., and in a fuel cell vehicle, hydrogen is obtained from a hydrogen tank that compresses hydrogen at high pressure and supplied to the fuel cell of hydrogen. Moisture is generated when the fuel cell generates electric power from hydrogen and oxygen, and the moisture obtained at this time is utilized as reformed water or used to humidify the hydrogen gas obtained from the hydrogen tank.

However, it is sufficient that the amount of water required for humidification of reformed water and hydrogen gas is a part of the water discharged from the fuel cell. Therefore, a tank for accumulating water discharged from the fuel cell is provided in the fuel cell system. For example, in the fuel cell system described in Patent Document 1, a collection tank is provided in the piping for circulating the anode exhaust gas, so that the water discharged from the fuel cell does not return to the fuel cell again.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2012-99445

The problem to be solved by the invention

In the fuel cell system including the canister described above, it is necessary to measure the water level in the canister. In addition, when the tank is tilted, it is also considered that the water cannot be supplied, so it is necessary to also detect the tilt of the tank. Therefore, the fuel cell system described in Patent Document 1 is provided with a water level sensor and an inclination sensor. However, since the water level sensor and the inclination sensor are independent sensors, not only a space for installing the two sensors is required, but also there is room for improvement in terms of reduction in the number of components and cost. In addition, this subject is not limited to a fuel cell system, It is applicable also to the other system provided with the tank which stores liquid.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid surface state detection device capable of measuring the liquid surface height in the tank and detecting the inclination of the tank, and a fuel cell system including the liquid surface state detection device.

solutions to problems

In order to achieve the above-mentioned purpose, the invention described in the technical solution 1 is a liquid level state detection device, which has:

The float part (for example, the float part 20 in the embodiment described later) can be stored in a tank (for example, the liquid storage tank 1 in the embodiment described later) that stores the liquid (for example, the liquid 2 in the embodiment described later). A guide rod (for example, a guide rod 45 in an embodiment to be described later) that is erected inside is guided to move in the up-down direction; and

A pair of electrode portions (for example, a pair of electrode portions 30, 50, and 60 in an embodiment described later) are integrally fixed to the float portion, and are arranged to face each other in the up-down direction,

The liquid level height in the tank and the inclination of the tank are detected based on the electrostatic capacitance between the pair of electrode portions that changes due to the dielectric constant of the insulator existing between the pair of electrode portions .

The invention described in claim 2 is the invention described in claim 1, wherein the shape of the pair of electrode portions is circular in plan view.

The invention described in claim 3 is based on the invention described in claim 2, wherein,

Based on the magnitude relationship obtained by comparing the electrostatic capacitance between the pair of electrode portions with the electrostatic capacitance in the case where the space between the pair of electrode portions is filled with liquid, and the relationship between the pair of electrode portions The inclination of the tank is detected based on the magnitude relationship obtained by comparing the electrostatic capacitance between the pair of electrode parts with the electrostatic capacitance when the pair of electrode parts is filled with air.

The invention described in claim 4 is based on the invention described in claim 1, wherein,

Each electrode part of the pair of electrode parts includes a plurality of divided electrode parts (for example, upper electrode plates 51 , 52 , 61 to 61 in an embodiment to be described later) divided in the oblique direction of the tank to be detected in plan view. 64 and lower electrode plates 53, 54, 65 to 68).

The invention described in claim 5 is based on the invention described in claim 4, wherein,

The shape of the divided electrode portion is a quarter circle that is line-symmetrical with respect to the inclination direction of the tank to be detected in a plan view.

The invention described in claim 6 is based on the invention described in claim 4 or 5, wherein,

The direction of inclination of the tank being detected is the same as the direction in which the liquid flows out of the tank.

The invention described in claim 7 is based on the invention described in any one of claims 4 to 6, wherein,

The inclination of the can is detected based on the magnitude relationship of the electrostatic capacitances between the divided electrode parts of the pair of electrode parts respectively located in the inclination direction of the can.

The invention described in claim 8 is a fuel cell system including the liquid level state detection device according to any one of claims 1 to 7 .

Invention effect

According to the invention described in claim 1, the liquid level state detection device of the present invention includes the float part which is movable in the up-down direction guided by the guide rod erected in the tank in which the liquid is stored, and a pair of electrode parts. Since the pair of electrode portions are integrally fixed to the float portion and are arranged to face each other in the up-down direction, the pair of electrode portions is based on the difference between the pair of electrode portions that varies depending on the dielectric constant of the insulator existing between the pair of electrode portions. The electrostatic capacitance can detect the liquid level in the tank and the inclination of the tank with one device.

According to the invention of Claim 2, the presence or absence of the inclination of a tank with respect to all directions can be detected by a pair of electrode parts which are circular in plan view.

According to the invention described in claim 3, based on the magnitude relationship obtained by comparing the electrostatic capacitance between the pair of electrode portions and the electrostatic capacitance in the case where the pair of electrode portions is filled with liquid, and a pair of The inclination of the tank can be detected based on the magnitude relationship between the electrostatic capacitance between the electrode parts and the electrostatic capacitance when the pair of electrode parts is filled with air, so that the electrostatic capacitance between the pair of electrode parts can be used to detect to detect the presence or absence of tilting of the tank with respect to all directions.

According to the invention described in claim 4, the inclination in the dividing direction of the divided electrode portion can be accurately detected by the plurality of divided electrode portions divided in the inclination direction of the detected tank.

According to the invention described in claim 5, the plurality of divided electrode parts in the quarter-circle shape that is line-symmetrical with respect to the inclination direction of the tank to be detected can accurately detect the division direction of the divided electrode part. tilt.

According to the invention described in claim 6, since the inclination direction of the tank to be detected is set to be the same as the direction in which the liquid flows out of the tank, it can be suitably used as a liquid level state detection device for detecting the inclination of the tank from which the liquid is discharged. use.

According to the invention described in claim 7, the inclination of the can is detected based on the magnitude relationship of the electrostatic capacitance between the divided electrode parts of the pair of electrode parts respectively located in the inclination direction of the can, so that the direction of the can can be detected with high accuracy. The inclination of the division direction of the divided electrode portion.

According to the invention described in claim 8, the reliability of the fuel cell system is improved.

Description of drawings

Fig. 1(a) is a vertical cross-sectional view showing a liquid level state detection device according to a first embodiment of the present invention installed in a tank, and Fig. 1(b) is a main part of the liquid level state detection device shown in Fig. 1(a) Enlarge the stereogram.

FIG. 2 is an enlarged view of a main part of the liquid level state detection device when the liquid level is equal to or higher than a predetermined height.

FIG. 3 is an enlarged view of a main part of the liquid level state detection device when the liquid level is lower than a predetermined height.

FIG. 4 is an enlarged view of a main part showing the liquid level state detection device according to the first embodiment, which is inclined due to the inclination of the liquid storage tank.

5( a ) is a perspective view showing a pair of electrode portions included in the liquid level state detection device according to the second embodiment of the present invention, FIG. 5( b ) is a plan view of the pair of electrode portions, and FIG. 5( c ) is a Circuit diagram of the counter electrode part.

FIG. 6( a ) is an enlarged view of the main part of the liquid level state detection device shown in FIG. 5 when the liquid storage tank is horizontal, and FIG. 6( b ) is the liquid level shown in FIG. 5 when the liquid storage tank is inclined in the A direction Fig. 6(c) is an enlarged view of the main part of the liquid level state detection device shown in Fig. 5 when the liquid storage tank is inclined in the B direction.

7( a ) is a perspective view showing a pair of electrode portions included in a liquid level state detection device according to a third embodiment of the present invention, FIG. 7( b ) is a plan view of the pair of electrode portions, and FIG. 7( c ) is a Circuit diagram of the counter electrode part.

Fig. 8(a) is an enlarged view of the main part of the liquid level state detection device shown in Fig. 7 when the liquid storage tank is inclined in the C direction, and Fig. 8(b) is an enlarged view of Fig. 7 when the liquid storage tank is inclined in the D direction The enlarged view of the main part of the liquid level state detection device.

FIG. 9( a ) is a plan view of a reforming water pump of a fuel cell system including a collection tank for storing reformed water, and FIG. 9( b ) is a side view of the reforming water pump.

FIG. 10 is an enlarged view of a main part of the liquid level state detection device shown in FIG. 5 that detects a state that is largely inclined in the C direction.

Symbol Description:

1 liquid storage tank; 2 liquid; 10, 10A, 10B liquid level detection device; 20 float part; 30, 50, 60 electrode part; 31, 51, 52, 61, 62, 63, 64 upper electrode plate; 32, 53, 54, 65, 66, 67, 68 lower electrode plate; 35 spacer column; 36 window; 45 guide rod; 46 stopper.

Detailed ways

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

(first embodiment)

1( a ) is a vertical cross-sectional view showing the configuration of the liquid level state detection device according to the first embodiment, and FIG. 1( b ) is an enlarged perspective view of a main part of the liquid level state detection device shown in FIG. 1( a ). As shown in FIG. 1( a ), the liquid level state detection device 10 is disposed in the liquid storage tank 1 , and detects the liquid level R of the stored liquid 2 and the inclination of the liquid storage tank 1 . It should be noted that the liquid level state detection device 10 is arranged so as to be slidable along the guide rod 45 erected from the bottom 1a of the liquid storage tank 1. Therefore, the inclination of the liquid storage tank 1 detected by the liquid level state detection device 10 is different from the inclination of the liquid storage tank 1. The inclination of the liquid level state detection device 10 is equal.

The liquid level state detection device 10 includes a float portion 20 and a pair of electrode portions 30 integrally fixed to the lower portion of the float portion 20 .

As shown in FIG. 2 , the float portion 20 is formed of a synthetic resin or the like in a hollow cylindrical shape having a sealed space 21 inside. A fluid having a specific gravity lower than that of the liquid 2 stored in the liquid storage tank 1 is enclosed in the sealed space 21 . For example, when the liquid 2 is water, air is enclosed in the sealed space 21 . Accordingly, the float portion 20 floats in the vicinity of the liquid surface R of the liquid 2 stored in the liquid storage tank 1 .

In addition, the float portion 20 includes a cover portion 22 capable of sealing the sealed space 21 . The buoyancy of the float 20 can be adjusted by opening the lid 22 and filling the sealed space 21 with a fluid with a specific gravity lower than that of the liquid 2 , so that various liquids having different specific gravities stored in the liquid storage tank 1 can be handled.

The pair of electrode portions 30 includes an upper electrode plate 31 and a lower electrode plate 32 which are arranged to face each other in the up-down direction, separated from each other by a predetermined distance L. The upper electrode plate 31 and the lower electrode plate 32 are each formed in a disk shape. The pair of electrode portions 30 of the present embodiment constitute electrodes of an electrostatic capacitance type sensor that utilizes electrostatic capacitance due to the intermediary of an insulator (for example, water or air) existing between the upper electrode plate 31 and the lower electrode plate 32 . change in electrical constant.

The upper electrode plate 31 is fixed to the lower surface of the bottom surface 23 of the float portion 20 , and the lower electrode plate 32 is fixed to the upper surface of the bottom plate 34 . The bottom surface 23 of the float portion 20 and the bottom plate 34 are connected by a plurality of spacer columns 35 extending in the vertical direction. The plurality of spacer pillars 35 are formed to be separated in the circumferential direction, and a window portion 36 is provided between adjacent spacer pillars 35 . Therefore, the space between the upper electrode plate 31 and the lower electrode plate 32 is opened to the outside through the plurality of windows 36, and the liquid 2 stored in the liquid storage tank 1 and the air in the liquid storage tank 1 can be freely taken in and out.

In addition, a support portion 39 is extended on the side of the pair of electrode portions 30 . The guide rod 45 is slidably fitted into the guide hole 40 formed in the support portion 39 and penetrating in the up-down direction. The guide rod 45 is a pipe erected from the bottom 1 a of the liquid storage tank 1 , and a stopper 46 for preventing the downward movement of the pair of electrode parts 30 is provided at the lower part of the guide rod 45 in order to detect the lowest position of the liquid level R. It should be noted that the cross-section of the guide rod 45 is rectangular, and the guide hole 40 has a shape corresponding to the cross-section of the guide rod 45. Therefore, the liquid level state detection device 10 slides and moves in the vertical direction along the guide rod 45, but does not The guide rod 45 rotates as a shaft.

Lead wires 37 are respectively connected to the upper electrode plate 31 and the lower electrode plate 32 , and one end of the lead wires 37 is connected to an output connector 38 . A processing unit (not shown) included in the liquid level state detection device 10 calculates the electrostatic capacitance between the pair of electrode portions 30 based on the potential difference between the pair of electrode portions 30 output from the output connector 38 and the like, and calculates the electrostatic capacitance between the pair of electrode portions 30 based on the The electrostatic capacitance detects the liquid level in the liquid storage tank 1 and the inclination of the liquid storage tank 1 . It should be noted that the signal indicating the potential difference between the pair of electrode portions 30 may be wirelessly transmitted to the processing unit. In addition, the processing unit may be provided outside the liquid storage tank 1 or may be provided in the sealed space 21 of the float unit 20 . When the processing unit is provided in the sealed space 21 , each signal indicating the liquid level in the liquid storage tank 1 and the inclination of the liquid storage tank 1 is output from the output connector 38 via the lead wire 37 .

The electrostatic capacitance C between the pair of electrode portions 30 is represented by equation (1).

C=ε×S/L…(1)

Here, "ε" is the dielectric constant [F/m] of the insulator existing between the upper electrode plate 31 and the lower electrode plate 32 , and "S" is the area of the upper electrode plate 31 and the lower electrode plate 32 [m ² ] ], "L" is the separation distance [m] between the upper electrode plate 31 and the lower electrode plate 32 .

When the height of the liquid surface R of the liquid 2 stored in the liquid storage tank 1 changes, the liquid surface state detection device 10 slides in the vertical direction guided by the guide rod 45 under the action of the float portion 20 . When the liquid 2 stored in the liquid storage tank 1 is larger than a predetermined amount, as shown in FIG. 2 , the space between the upper electrode plate 31 and the lower electrode plate 32 is filled with the liquid 2 . On the other hand, when the liquid 2 stored in the liquid storage tank 1 decreases and the liquid level R is lower than the position of the stopper 46 provided in the guide rod 45 as shown in FIG. 3 , the upper electrode plate 31 and the lower electrode plate 32 The space between is exposed to the air.

In the state shown in FIG. 2, the space between the upper electrode plate 31 and the lower electrode plate 32 is filled with the liquid 2, and when the liquid 2 is water, its relative permittivity εr is 80.4 (at 20°C), Therefore, the electrostatic capacitance between the pair of electrode portions 30 exhibits a larger value than the state shown in FIG. 3 in which the space between the upper electrode plate 31 and the lower electrode plate 32 is exposed to the air. On the other hand, since the relative permittivity εr of air is 1.00059, in a state where the space between the upper electrode plate 31 and the lower electrode plate 32 shown in FIG. 3 is exposed to the air, the gap between the pair of electrode portions 30 is The electrostatic capacitance exhibits a small value. It should be noted that the relative permittivity εr refers to the ratio between the permittivity ε of the insulator (medium) existing between the upper electrode plate 31 and the lower electrode plate 32 and the permittivity ε0 of the vacuum (εr=g /ε0).

Therefore, in the present embodiment, it can be detected whether the height of the liquid 2 stored in the liquid storage tank 1 is lower than the stopper 46 provided in the guide rod 45 by calculating the electrostatic capacitance between the pair of electrode parts 30 .

Next, when the liquid storage tank 1 is inclined, detection of the inclination by the liquid level state detection device 10 will be described with reference to FIG. 4 .

When the liquid storage tank 1 is inclined, the liquid level state detection device 10 is also inclined. When the liquid level detection device 10 is tilted in a state where the liquid level of the liquid 2 stored in the liquid storage tank 1 is higher than the stopper 46 provided in the guide rod 45, the upper electrode plate 31 and the lower A part of the space between the electrode plates 32 is exposed to the air, and the liquid 2 and air are mixed in this space. The electrostatic capacitance C3 between the pair of electrode portions 30 in this state varies according to the mixing ratio of the liquid 2 and the air, and the space between the upper electrode plate 31 and the lower electrode plate 32 shown in FIG. 2 is filled with the liquid 2 than the space between the upper electrode plate 31 and the lower electrode plate 32 shown in FIG. The electrostatic capacitance C1 is smaller (C3 < C1 ) in the case of , and larger than the electrostatic capacitance C2 in the case where the space between the upper electrode plate 31 and the lower electrode plate 32 shown in FIG. 3 is filled with air (C2 < C3 ) . That is, the relationship of C2<C3<C1 holds.

Therefore, in the present embodiment, the inclination of the liquid storage tank 1 can be detected by comparing the electrostatic capacitance calculated from the potential difference between the pair of electrode portions 30 and the electrostatic capacitances C1 and C2 and deriving the magnitude relationship. It should be noted that the capacitances C1 and C2 are values peculiar to the type of the liquid 2 stored in the liquid storage tank 1 and the structure of the pair of electrode portions 30 , and therefore pre-measured values are recorded in a memory or the like not shown. .

In addition, since the top electrode plate 31 and the lower electrode plate 32 constituting the pair of electrode portions 30 are circular in plan view, although the tilt direction cannot be detected in the present embodiment, it is possible to detect the inclination direction of the upper electrode plate 31 or the lower electrode plate 32 . The presence or absence of tilt is detected in all directions in the circumferential direction. Furthermore, the detection accuracy of the tilt can be changed by adjusting at least one of the area S of the upper electrode plate 31 and the lower electrode plate 32 and the separation distance L of the upper electrode plate 31 and the lower electrode plate 32 .

(Second Embodiment)

5( a ) is a perspective view showing a pair of electrode portions included in a liquid level state detection device according to a second embodiment of the present invention, and FIG. 5( b ) is a plan view of the pair of electrode portions shown in FIG. 5( a ) , Fig. 5(c) is a circuit diagram of a pair of electrode portions shown in Fig. 5(a). The difference between the liquid level state detection device 10A of the second embodiment and the liquid level state detection device 10 of the first embodiment is the configuration of a pair of electrode portions. Except for this point, it is the same as that of the first embodiment, and therefore the same or equivalent parts as those of the first embodiment are denoted by the same symbols or equivalent symbols, and the description is simplified or omitted.

As shown in FIGS. 5( a ) and 5 ( b ), each electrode portion of the pair of electrode portions 50 included in the liquid level state detection device 10A of the second embodiment has an inclination with respect to the liquid storage tank 1 to be detected. The direction (AB direction) is formed as two divided electrode portions which are line-symmetrical and divided in the above-mentioned oblique direction. That is, the upper electrode portion constituting the pair of electrode portions 50 is composed of two upper electrode plates 51 and 52 in a quarter circle shape, and the lower electrode portion is composed of two lower electrode plates 53 and 54 in a quarter circle shape. . As shown in FIG. 5( c ), the pair of electrode portions 50 of the present embodiment constitute an electrostatic capacitance sensor having an electrostatic capacitance Ca in which an upper electrode plate 51 and a lower electrode plate 53 are a pair, and an upper electrode plate 52 and a lower electrode plate 52 . The electrode plate 54 is a pair of electrodes of the electrostatic capacitance type sensor of the electrostatic capacitance Cb.

FIG. 6( a ) is an enlarged view showing the main part of the liquid level state detection device 10A when the liquid storage tank 1 is horizontal, and FIG. 6( b ) is an enlarged view of the liquid level state detection device 10A when the liquid storage tank 1 is inclined in the A direction. 6( c ) is an enlarged view of the main part showing the liquid level state detection device 10A when the liquid storage tank 1 is inclined in the B direction. The liquid storage tank 1 shown in FIGS. 6(a) to 6(c) in each state (horizontal state, inclined state inclined in direction A, and inclined state inclined in direction B) existing in a pair of electrode portions The insulator and capacitance Ca and Cb of 50 are shown in Table 1 below.

【Table 1】

As shown in Table 1, when the liquid storage tank 1 is in a horizontal state (see FIG. 6( a )), the space between the upper electrode plate 51 and the lower electrode plate 53 and the space between the upper electrode plate 52 and the lower electrode plate 54 The space between is filled with liquid 2 (water) whose relative permittivity εr is larger than that of air, so it becomes electrostatic capacitance Ca = electrostatic capacitance Cb.

On the other hand, when the liquid storage tank 1 is inclined in the direction A (see FIG. 6( b )), the space between the upper electrode plate 51 and the lower electrode plate 53 is filled with the liquid 2 (water), but the upper electrode plate A part of the space between 52 and the lower electrode plate 54 protrudes upward from the liquid surface R and the liquid 2 (water) and air are mixed, so that the capacitance Ca>the capacitance Cb is satisfied.

In addition, in the state where the liquid storage tank 1 is inclined in the direction B (see FIG. 6( c )), a part of the space between the upper electrode plate 51 and the lower electrode plate 53 protrudes upward from the liquid surface R, and the liquid 2 is mixed with it. (water) and air, since the space between the upper electrode plate 52 and the lower electrode plate 54 is filled with the liquid 2 (water), the capacitance Ca<the capacitance Cb is satisfied.

Therefore, in the present embodiment, liquid can be detected based on the magnitude relationship between the electrostatic capacitance Ca between the upper electrode plate 51 and the lower electrode plate 53 and the electrostatic capacitance Cb between the upper electrode plate 52 and the lower electrode plate 54 Whether the storage tank 1 is horizontal, is inclined in the A direction, or is inclined in the B direction. It should be noted that, in the present embodiment, as in the first embodiment, by calculating at least one of the electrostatic capacitances Ca and Cb between the pair of electrode portions 50 , it is possible to detect the amount of water stored in the liquid storage tank 1 . Is the height of the liquid 2 lower than the stopper 46 provided on the guide rod 45 .

(third embodiment)

7( a ) is a perspective view showing a pair of electrode portions included in a liquid level state detection device according to a third embodiment of the present invention, and FIG. 7( b ) is a plan view of the pair of electrode portions shown in FIG. 7( a ) , FIG. 7(c) is a circuit diagram of a pair of electrode portions shown in FIG. 7(a). The liquid level state detection device 10B of the third embodiment is different from the liquid level state detection device 10 of the first embodiment in the configuration of a pair of electrode portions. Except for this point, it is the same as that of the first embodiment, and therefore the same or equivalent parts as those of the first embodiment are denoted by the same symbols or equivalent symbols, and the description is simplified or omitted.

As shown in FIGS. 7( a ) and 7 ( b ), each electrode part of the pair of electrode parts 60 included in the liquid level state detection device 10B of the third embodiment has an inclination with respect to the liquid storage tank 1 to be detected The directions (AB direction and CD direction) are formed as four divided electrode portions which are line-symmetrical and divided in the above-mentioned oblique direction. That is, the upper electrode portion constituting the pair of electrode portions 60 is composed of four upper electrode plates 61 to 64 in a quarter circle shape, and the lower electrode portion is composed of four lower electrode plates 65 to 68 in a quarter circle shape . As shown in FIG. 7( c ), the pair of electrode portions 60 of the present embodiment constitute an electrostatic capacitance sensor having an electrostatic capacitance Ca in which an upper electrode plate 61 and a lower electrode plate 65 are a pair, an upper electrode plate 62 and a lower electrode The plate 66 is an electrostatic capacitance sensor having a pair of electrostatic capacitance Cb, an electrostatic capacitance sensor having a pair of electrostatic capacitance Cc of the upper electrode plate 63 and the lower electrode plate 67 , and the upper electrode plate 64 and the lower electrode plate 68 are A pair of electrodes of the electrostatic capacitance sensor of the electrostatic capacitance Cd of these four sensors.

FIG. 8( a ) is an enlarged view showing the main part of the liquid level state detection device 10B when the liquid storage tank 1 is inclined in the C direction, and FIG. 8( b ) is an enlarged view showing the liquid level state detection when the liquid storage tank 1 is inclined in the D direction An enlarged view of the main part of the device 10B. 8(a) and 8(b) in each state of the liquid storage tank 1 (horizontal state, inclined state inclined in direction A, inclined state inclined in direction B, inclined state inclined in direction C, The insulators and electrostatic capacitances Ca, Cb, Cc, and Cd present in the pair of electrode portions 60 in the inclined state inclined in the D direction) are shown in Table 2 below.

【Table 2】

As shown in Table 2, when the liquid storage tank 1 is in a horizontal state (see FIG. 6( a )), the space between the upper electrode plate 61 and the lower electrode plate 65 and the space between the upper electrode plate 62 and the lower electrode plate 66 The space, the space between the upper electrode plate 63 and the lower electrode plate 67 , and the space between the upper electrode plate 64 and the lower electrode plate 68 are all filled with the liquid 2 (water) whose relative permittivity εr is larger than that of air, and thus become Electrostatic capacitance Ca=Electrostatic capacitance Cb=Electrostatic capacitance Cc=Electrostatic capacitance Cd.

On the other hand, in a state where the liquid storage tank 1 is inclined in the direction A (see FIG. 6( b )), the space between the upper electrode plate 61 and the lower electrode plate 65 is filled with the liquid 2 (water), but the upper electrode plate 65 is filled with the liquid 2 (water). A part of the space between 62 and the lower electrode plate 66 protrudes upward from the liquid surface R, and the liquid 2 (water) and air are mixed, so that the capacitance Ca>the capacitance Cb is satisfied. At this time, the liquid 2 (water) and air are mixed in the space between the upper electrode plate 63 and the lower electrode plate 67 and the space between the upper electrode plate 64 and the lower electrode plate 68, but the mixing degree is the same, so It becomes electrostatic capacitance Cc=electrostatic capacitance Cd. In this way, the electrostatic capacitance between the pair of electrode portions 60 in the state where the liquid storage tank 1 is inclined in the A direction becomes "capacitance Ca>capacitance Cb and capacitance Cc=capacitance Cd".

In addition, in the state where the liquid storage tank 1 is inclined in the direction B (see FIG. 6( c )), a part of the space between the upper electrode plate 61 and the lower electrode plate 65 protrudes upward from the liquid surface R, and the liquid 2 is mixed with it. (water) and air, since the space between the upper electrode plate 62 and the lower electrode plate 66 is filled with the liquid 2 (water), the capacitance Ca<the capacitance Cb is satisfied. At this time, the liquid 2 (water) and air are mixed in the space between the upper electrode plate 63 and the lower electrode plate 67 and the space between the upper electrode plate 64 and the lower electrode plate 68, but the mixing degree is the same, so It becomes electrostatic capacitance Cc=electrostatic capacitance Cd. In this way, the electrostatic capacitance between the pair of electrode portions 60 in the state where the liquid storage tank 1 is inclined in the B direction becomes "capacitance Ca<capacitance Cb and capacitance Cc=capacitance Cd".

In addition, in the state where the liquid storage tank 1 is inclined in the C direction (see FIG. 8( a )), the space between the upper electrode plate 61 and the lower electrode plate 65 and the space between the upper electrode plate 62 and the lower electrode plate 66 The liquid 2 (water) and air are mixed in the space, but since the degree of mixing is the same, the capacitance Ca=the capacitance Cb. In addition, the space between the upper electrode plate 63 and the lower electrode plate 67 is filled with the liquid 2 (water), but a part of the space between the upper electrode plate 64 and the lower electrode plate 68 protrudes upward from the liquid surface R and is mixed with the liquid 2 (water) and air, so it becomes electrostatic capacitance Cc>electrostatic capacitance Cd. In this way, the electrostatic capacitance between the pair of electrode portions 60 in the state where the liquid storage tank 1 is inclined in the C direction becomes "electrostatic capacitance Ca=electrostatic capacitance Cb and electrostatic capacitance Cc>electrostatic capacitance Cd".

In addition, in the state where the liquid storage tank 1 is inclined in the D direction (see FIG. 8( b )), the space between the upper electrode plate 61 and the lower electrode plate 65 and the space between the upper electrode plate 62 and the lower electrode plate 66 The liquid 2 (water) and the air are mixed in the space, but since the degree of mixing is approximately the same, the capacitance Ca=the capacitance Cb. In addition, a part of the space between the upper electrode plate 63 and the lower electrode plate 67 protrudes upward from the liquid surface R to mix the liquid 2 (water) and air, and the space between the upper electrode plate 64 and the lower electrode plate 68 is made of liquid Since 2 (water) is full, it becomes electrostatic capacitance Cc < electrostatic capacitance Cd. In this way, the electrostatic capacitance between the pair of electrode portions 60 in the state where the liquid storage tank 1 is inclined in the D direction becomes "capacitance Ca=capacitance Cb and capacitance Cc<capacitance Cd".

Therefore, in this embodiment, based on the electrostatic capacitance Ca between the upper electrode plate 61 and the lower electrode plate 65, the electrostatic capacitance Cb between the upper electrode plate 62 and the lower electrode plate 66, the upper electrode plate 63 and the lower electrode plate The magnitude relationship between the electrostatic capacitance Cc between the upper electrode plate 64 and the lower electrode plate 68 and the electrostatic capacitance Cd between the upper electrode plate 64 and the lower electrode plate 68 can detect whether the liquid storage tank 1 is horizontal, or inclined in the direction A, or in the direction B. The state in which the direction is inclined, the state in which it is inclined in the C direction, or the state in which the direction is inclined in the D direction. It should be noted that, in the present embodiment, as in the first embodiment, by calculating at least one of the electrostatic capacitances Ca, Cb, Cc, and Cd between the pair of electrode portions 60, it is possible to detect the storage in the liquid. Is the height of the liquid 2 in the storage tank 1 lower than the stopper 46 provided on the guide rod 45 .

It should be noted that the relationship between the direction in which the liquid storage tank 1 is inclined and the respective electrostatic capacitances Ca, Cb, Cc, and Cd at this time is mapped in advance, and the calculated electrostatic capacitances Ca, Cb, Cc, and Cd can be used to map the relationship. Detection of the inclination in the intermediate direction between the AB direction and the CD direction described above. In addition, not limited to the AB direction and the CD direction, by dividing a pair of electrode portions in the tilt direction to be detected and providing the divided electrode portions, the tilt in the desired direction can be accurately detected.

【Example】

Next, an embodiment in which the liquid level state detection device described above is applied to a fuel cell system will be described. In addition, the liquid level state detection apparatus used here is the liquid level state detection apparatus 10A of 2nd Embodiment provided with a pair of electrode part 50 shown in FIG.

FIG. 9( a ) is a plan view of a reformed water pump including a collection tank for storing reformed water, and FIG. 9( b ) is a side view of the reformed water pump shown in FIG. 9( a ). The reformed water pump 70 takes in reformed water from the water supply port 71 provided in the lower part, and sends the water in the X direction from the water discharge port 72 .

The supply rate of the reforming water supplied by the reforming water pump 70 is, for example, 5 cc/min, which is a small amount, and therefore requires precise control. Therefore, the inclination of the reformed water pump 70, in particular, the inclination to the water supply direction (X direction) of the reformed water needs to be detected with high accuracy. As an example of the fuel cell system, when the inclination of the reformed water pump 70 in the water supply direction of the reformed water is detected, the control of emergency stop of the fuel cell system is performed.

On the other hand, if the inclination of the reformed water pump 70 in directions other than the water supply direction (X direction) is slight, there is no major problem in the water supply of the reformed water, and an emergency stop of the fuel cell system is not required. On the other hand, excessive inclination may affect not only the water supply of the reformed water, but also the operation of other devices, so the fuel cell system is urgently stopped.

In the liquid level state detection device 10A of the present embodiment, the division directions (AB directions) of the two divided electrode portions divided in each electrode portion of the pair of electrode portions 50 shown in FIG. 5( b ) are arranged to be the same as the The water feeding direction (X direction) of the reforming water pump 70 is the same. In the liquid level state detection device 10A, if the relationship of the electrostatic capacitance is "electrostatic capacitance Ca>electrostatic capacitance Cb" or "electrostatic capacitance Ca<electrostatic capacitance Cb", it is detected that the reformed water pump 70 is inclined in the A direction or the B direction, Therefore, the fuel cell system is urgently stopped.

In addition, insulators and electrostatic capacitances Ca existing in the pair of electrode portions 50 in a state in which the reforming water pump 70 is inclined in the C direction and the D direction orthogonal to the water feeding direction (X direction, AB direction) of the reforming water pump 70 , Cb are shown in Table 3 below.

【table 3】

As shown in Table 3, when the inclination of the reformed water pump 70 in the C direction or the D direction is a slight inclination, a part of the pair of electrode parts 50 protrudes upward from the liquid surface R, so the upper electrode plate 51 and the upper electrode plate 51 are connected to each other. The space between the lower electrode plates 53 and the space between the upper electrode plate 52 and the lower electrode plate 54 are mixed with a large amount of liquid 2 (modified water) and a small amount of air to the same degree, and the capacitance Ca = capacitance Cb . The values of the capacitances Ca and Cb at this time are mainly determined by the relative permittivity εr of the liquid 2 .

On the other hand, when the inclination of the reforming water pump 70 in the C direction or the D direction is excessive, as shown in FIG. 10 , most of the pair of electrode parts 50 protrude upward from the liquid surface R, so the upper part is The space between the electrode plate 51 and the lower electrode plate 53 and the space between the upper electrode plate 52 and the lower electrode plate 54 are mixed with a large amount of air and a small amount of the liquid 2 (modified water) to the same degree, and the capacitance Ca becomes =Electrostatic capacitance Cb. The values of the capacitances Ca and Cb at this time are mainly determined by the relative permittivity εr of air.

In this way, the value of the electrostatic capacitance between the pair of electrode parts 50 when the reformed water pump 70 is inclined in the C direction or the D direction changes according to the inclination angle of the reformed water pump 70, so the inclination angle of the reformed water pump 70 is related to the electrostatic capacitance A map is created in advance for the value of , and a threshold value is set for the electrostatic capacitance, so that when the reforming water pump 70 is excessively inclined in the C direction or the D direction at right angles to the water supply direction (X direction), a stop warning of the fuel cell system, etc. can be performed. .

As described above, the liquid level state detection apparatuses 10 , 10A, and 10B of the first to third embodiments include the float unit 20 and the pair of electrode units 30 , 50 , and 60 , and the float unit 20 can be stored in the liquid The guide rod 45 erected in the liquid storage tank 1 of the The electrostatic capacitance between the pair of electrode portions 30 , 50 , and 60 , which is changed by the dielectric constant of the insulator existing between the pair of electrode portions 30 , 50 , and 60 , can be detected by a single device in the liquid storage tank 1 . The liquid level and the inclination of the liquid storage tank 1.

In addition, the shape of the pair of electrode portions 30 included in the liquid level state detection device 10 of the first embodiment is circular in plan view. Furthermore, based on the magnitude relationship obtained by comparing the electrostatic capacitance between the pair of electrode portions 30 and the electrostatic capacitance C1 when the space between the pair of electrode portions 30 is filled with the liquid 2 , and the relationship between the pair of electrode portions 30 The inclination of the liquid storage tank 1 is detected based on the magnitude relationship obtained by comparing the electrostatic capacitance between the pair of electrode portions 30 with the electrostatic capacitance C2 when the space between the pair of electrode portions 30 is filled with air. Therefore, the presence or absence of inclination of the liquid storage tank 1 with respect to all directions can be detected from the electrostatic capacitance between the pair of electrode portions 30 .

In addition, the upper electrode portion constituting the pair of electrode portions 50 included in the liquid level state detection device 10A according to the second embodiment includes two upper electrode plates 51 divided in the inclination direction of the liquid storage tank 1 to be detected in plan view. , 52 , the lower electrode portion also includes two lower electrode plates 53 and 54 divided in the above-mentioned oblique direction, based on the difference between the divided electrode parts of the pair of electrode parts 50 respectively located in the oblique direction of the liquid storage tank 1 Since the inclination of the liquid storage tank 1 is detected based on the magnitude relationship of the electrostatic capacitance, the inclination of the liquid storage tank 1 in the direction of dividing the electrode plates of each electrode portion can be accurately detected.

In addition, the upper electrode portion constituting the pair of electrode portions 60 included in the liquid level state detection device 10B according to the third embodiment includes four upper electrode plates 61 to 64 in the shape of a quarter circle. These four upper electrode plates 61 ～ 64 are formed in line symmetry with respect to two inclination directions orthogonal to each other of the liquid storage tank 1 to be detected in a plan view, and the lower electrode portion similarly includes four lower electrode plates 65 to 68 in the shape of a quarter circle. The four lower electrode plates 65 to 68 are formed in line symmetry with respect to the above-mentioned two orthogonal inclination directions, and are based on the static electricity between the divided electrode parts of the pair of electrode parts 60 respectively located in the inclination direction of the liquid storage tank 1 . Since the inclination of the liquid storage tank 1 is detected based on the magnitude relationship of the capacitance, the inclination of the liquid storage tank 1 in the two orthogonal division directions of the electrode plates of each electrode portion can be accurately detected.

In addition, the detected inclination direction of the liquid storage tank 1 includes the direction in which the liquid 2 flows out of the liquid storage tank 1. Therefore, the liquid level state detection devices 10A and 10B of the second and third embodiments can be suitably used for detection of a fuel cell system The inclined liquid level state detection device of the reforming water pump 70 is used.

In addition, the reliability of the fuel cell system including the liquid level state detection devices 10, 10A, and 10B is improved.

In addition, this invention is not limited to the above-mentioned embodiment, A deformation|transformation, improvement, etc. are possible suitably. For example, the liquid level detection devices 10, 10A, and 10B are not limited to the application to fuel cell systems, and can be applied to tanks that require simultaneous detection of the liquid level and inclination of the stored liquid regardless of the type and application of the liquid. .

Claims (9)

1. A liquid level state detection device is characterized in that,

the liquid surface state detection device is provided with:

a float part which can move in the vertical direction guided by a guide rod erected in a tank for storing liquid; and

a pair of electrode portions integrally fixed to the float portion and arranged to face each other in the vertical direction,

the liquid level height in the tank and the inclination of the tank are detected based on an electrostatic capacitance between the pair of electrode portions that changes due to a dielectric constant of an insulator present between the pair of electrode portions.

2. A liquid level condition detection device according to claim 1,

the pair of electrode portions are circular in shape in a plan view.

3. A liquid level condition detection device according to claim 2,

the inclination of the tank is detected based on a magnitude relationship obtained by comparing the capacitance between the pair of electrode portions with the capacitance in a case where the pair of electrode portions is filled with the liquid, and a magnitude relationship obtained by comparing the capacitance between the pair of electrode portions with the capacitance in a case where the pair of electrode portions is filled with the air.

4. A liquid level condition detection device according to claim 1,

each electrode portion of the pair of electrode portions includes a plurality of divided electrode portions divided in a direction in which the tank to be detected is inclined in a plan view.

5. A liquid level condition detection device according to claim 4,

the shape of the divided electrode portion is a quarter circle that is line-symmetric with respect to the inclination direction of the tank to be detected in a plan view.

6. A liquid level condition detection device according to claim 4 or 5,

the direction of inclination of the tank being detected includes the direction of liquid flow out of the tank.

7. A liquid level condition detection device according to claim 4 or 5,

the inclination of the tank is detected based on a magnitude relationship of capacitance between the respective divided electrode portions of the pair of electrode portions respectively positioned in the inclination direction of the tank.

8. A liquid level condition detection device according to claim 6,

the inclination of the tank is detected based on a magnitude relationship of capacitance between the respective divided electrode portions of the pair of electrode portions respectively positioned in the inclination direction of the tank.

9. A fuel cell system, characterized in that,

the fuel cell system is provided with the liquid surface state detection device according to any one of claims 1 to 8.

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