JP2006302579A - Fuel cell cooling system and measuring structure of conductivity of cooling liquid circulation line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve measurement accuracy of conductivity sensor 14 as well as improve detection responsibility. <P>SOLUTION: The fuel cell cooling system 10 is provided with a bypass line 20 fitted in parallel at a part of a cooling liquid circulation line L1, a conductivity sensor 14 arranged at the bypass line 20 for measuring conductivity of cooling liquid, and a porous member 15 arranged at an upstream side of the conductivity sensor of the bypass line 20. For that, cooled liquid without any large air bubble with stable flow is supplied at all times to the conductivity sensor 14 at a downstream side of the porous member 15. As a result, measurement accuracy of the conductivity sensor 14 is enhanced to improve on detection responsibility. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell cooling system, and more particularly to a structure for measuring the conductivity of a coolant in a coolant circulation line.

  The fuel cell cooling system includes a coolant circulation line for circulating a coolant, and a fuel cell, a radiator, and a coolant pump provided in the middle of the coolant circulation line.

  In such a fuel cell cooling system, if the conductivity of the coolant increases, the fuel cell and the auxiliary equipment of the fuel cell may be adversely affected. Therefore, when the conductivity of the coolant increases, the conductivity is reduced. Need to be low. Therefore, the measurement accuracy of the conductivity of the coolant is important.

Patent Document 1 discloses that a conductivity sensor is placed in a closed branch pipe branched from a coolant circulation line so that the conductivity sensor is not affected by pulsation of the coolant circulation line in order to increase the measurement accuracy of the conductivity sensor. Proposed technology to be deployed.
JP 2000-009685 A

  However, in the prior art, the cooling liquid stays in the closed branch pipe portion for a long time. Therefore, the conductivity sensor in the closed branch pipe cannot immediately detect the change in the conductivity of the coolant flowing through the coolant circulation line, and the detection response is poor.

  An object of the present invention is to provide a fuel cell cooling system capable of improving detection responsiveness while improving measurement accuracy of a conductivity sensor and a structure for measuring conductivity of a coolant circulation line.

  The fuel cell cooling system of the present invention is provided in parallel with a coolant circulation line for circulating coolant, a fuel cell and a radiator provided in the middle of the coolant circulation line, and a part of the coolant circulation line. A bypass line, a conductivity sensor that is disposed in the bypass line and that measures a conductivity of a coolant flowing through the bypass line, and a porosity that is disposed upstream of the conductivity sensor in the bypass line. A member. In the present invention, the porous member includes a porous member in addition to a porous film and a mesh, and also includes a combination of a plurality of these members.

  According to the present invention, a part of the coolant flowing through the coolant circulation line flows into the bypass line. The flow velocity and flow rate of the coolant flowing into the bypass line are attenuated by the porous member, and the flow velocity disturbance and the flow velocity disturbance are also attenuated. Moreover, even if air bubbles are mixed in the coolant, the air bubbles become fine due to the porous member. For this reason, the conductivity sensor on the downstream side of the porous member is always supplied with a coolant that does not contain large bubbles and has a stable flow. As a result, the measurement accuracy of the conductivity sensor is improved and the detection responsiveness is improved.

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

First Embodiment A structure for measuring the conductivity of a fuel cell cooling system and a cooling circulation line according to a first embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram of a fuel cell cooling system.

  As shown in FIG. 1, the fuel cell cooling system 10 of this embodiment includes a coolant circulation line L for circulating a coolant (cooling water in this example), and a fuel cell provided in the middle of the coolant circulation line L. A fuel cell stack 11, a radiator 12 as a radiator, and a coolant pump 13 as a pressure feeding means. By operating the pump 13, the coolant is circulated through the coolant circulation line L, and the fuel cell 11 This heat is dissipated by the radiator 12.

  The coolant circulation line L of this embodiment includes a line L1 that connects the fuel cell 11 and the radiator 12, a line L2 that connects the radiator 12 and the pump 13, and a pump 13 and the fuel cell 11. A line L3 to be connected.

  A bypass line 20 provided in parallel with a part of the line L1 is branched and connected to the line L1 of the coolant circulation line L.

  2 is an enlarged cross-sectional view of a bypass line of the fuel cell cooling system of FIG.

  As shown in FIG. 2, the bypass line 20 includes a downward passage 22 extending downward from a branch point 21 from the coolant circulation line L1 (that is, a base end portion of the bypass line), and a lower end 23 (curved portion) of the downward passage 22. A lateral passage 24 extending laterally from the horizontal passage 24 and an upward passage 26 extending upward from an end point 25 (curved portion) of the lateral passage 24. The bypass line 20 joins the coolant circulation line L1 again at the upper end 27 of the upward passage 26 (that is, the junction with the coolant circulation line L1).

  As shown in FIG. 2, for example, a porous member 15 such as a porous film or a mesh, and a conductivity sensor 14 that measures the conductivity of the coolant are arranged in the bypass line 20. The conductivity sensor 14 is disposed at the curved portion 25 that is the intersection of the lateral passage 24 and the upward passage 26, and the porous member 15 is disposed upstream of the conductivity sensor 14.

  FIG. 3 is an enlarged cross-sectional view of the vicinity of the conductivity sensor of the bypass line of FIG.

  As shown in FIG. 3, the conductivity sensor 14 includes a rod-shaped inner pole 31, a cylindrical outer pole 32, a cylindrical protective tube 33, and a sensor body 35 that fixes them. The inner pole 31, the outer pole 32, and the protective tube 33 are arranged coaxially, the outer pole 32 is arranged in the protective tube 33, and the inner pole 31 in the outer pole 32 is arranged. The opening end of the cylindrical protective tube 33 is arranged toward the upstream side of the bypass line 20, and the coolant flows into the protective tube 33.

  A through hole 37 is provided in the peripheral wall portion of the protective tube 33 so that the coolant flowing into the protective tube 33 can be discharged out of the protective tube 33. The through hole 37 is directed upward, that is, downstream of the upward passage. Similarly, the cylindrical outer pole 32 is provided with a through hole (not shown). The through hole of the outer pole 32 also faces upward. With such a configuration, the coolant always flows between the electrodes 31 and 32 of the sensor 14.

  The conductivity of the coolant flowing between the electrodes 31 and 32 of the conductivity sensor 14 can be obtained by applying a constant voltage to the electrodes 31 and 32 and measuring the current value. The conductivity [k] is obtained by the following formula. The cell constant [K] is a constant determined by the shape and size of the electrode.

Conductivity [k] = cell constant [K] × (current [I] / voltage [V])
FIG. 4 is a diagram showing a vertical positional relationship between the coolant circulation line and the bypass line, and is a cross-sectional view taken along line IV-IV in FIG.

  As shown in FIG. 4, the base end portion 21 of the bypass line 20 is provided obliquely downward on the lower side of the center line C of the coolant circulation line L1. That is, the bypass line 20 is disposed below the center line C of the coolant circulation line L1. Further, the lateral passage 24 in which the conductivity sensor 14 is disposed in the bypass line 20 is provided below the lowermost surface 29 of the coolant circulation line.

  Next, the operation of this embodiment will be described.

  When the pump 13 is operated, the coolant circulates in the coolant circulation line L (L1, L2, L3), and the heat generated in the fuel cell 11 is radiated by the radiator 12 (see FIG. 1). At this time, a part of the coolant flowing through the coolant circulation line L1 flows into the bypass line 20 as shown in FIG. The flow rate and flow rate of the coolant that has flowed into the bypass line 20 are attenuated by the porous member 15, and the disturbance of the flow rate and the flow rate are also attenuated. Even if bubbles are mixed in the coolant, the bubbles are made fine by the porous member 15. Therefore, a low-speed cooling liquid that does not contain large bubbles and has a stable flow is always supplied to the conductivity sensor 14 on the downstream side of the porous member 15.

  As shown in FIG. 3, the coolant supplied into the conductivity sensor 14 circulates between the inner electrode 31 and the outer electrode, and then the through hole (not shown) of the outer electrode 32 and the protective tube 33. Return to the upward passage 26 of the bypass line 20 through the through hole 37. As shown in FIG. 2, the coolant that has finally passed through the bypass line 20 joins the coolant circulation line L1 at the junction 27 and circulates through the coolant circulation line L again.

  As described above, according to the present embodiment, the conductivity sensor 14 is always supplied with a relatively low-speed cooling liquid that does not contain large bubbles and has a stable flow, so that the measurement accuracy of the conductivity sensor 14 is improved. As a result, the detection response is improved.

  Next, the effects of this embodiment will be summarized.

  1stly, the measurement structure of the electric conductivity of the fuel cell cooling system 10 of this embodiment and the cooling fluid circulation line L is the bypass line 20 provided in parallel with a part of the cooling fluid circulation line L1, and the bypass line 20 And a porous sensor 15 disposed on the upstream side of the conductivity sensor 14 of the bypass line 20.

  Therefore, the porous member 15 attenuates the flow rate and flow rate of the coolant flowing into the bypass line 20, and also attenuates the flow rate disturbance and the flow rate disturbance. Even if bubbles are mixed in the coolant, the bubbles are made fine by the porous member 15. That is, the conductivity sensor 14 on the downstream side of the porous member 15 is always supplied with a coolant that does not contain large bubbles and has a stable flow. As a result, the measurement accuracy of the conductivity sensor 14 is improved and the detection response is improved.

  Secondly, in the present embodiment, the base end portion 21 of the bypass line 20 is provided below the center line C of the coolant circulation line L1. That is, the bypass line 20 is provided below the center line C of the coolant circulation line L1. Therefore, it is difficult for bubbles to enter the bypass line 20 from the coolant circulation line L1, and a structure in which large bubbles are more difficult to enter between the electrodes of the conductivity sensor 14 is obtained.

  Thirdly, in the present embodiment, the passage 24 in which the conductivity sensor 14 is disposed in the bypass line 20 is provided below the bottom surface 29 of the coolant circulation line L1. Therefore, a structure in which large bubbles are more difficult to enter between the electrodes of the conductivity sensor 14 is obtained.

  Hereinafter, other embodiments of the present invention will be described. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description of a structure and an effect is abbreviate | omitted.

Second Embodiment FIG. 5 is a sectional view of a bypass line of a fuel cell cooling system according to a second embodiment.

  In the second embodiment, in the bypass line 20, delivery means 16 that sends out the coolant from the upstream side to the downstream side of the bypass line 20 is provided. The delivery means 16 is disposed upstream of the porous member 15. More specifically, it is disposed in the curved portion 23 that is the intersection of the downward passage 22 and the lateral passage 24.

  Thus, in 2nd Embodiment, since the delivery means 16 which sends out a cooling fluid in the bypass line 20 is provided, when the flow of the cooling fluid which goes to the conductivity sensor 14 is insufficient, the cooling liquid which goes to the conductivity sensor 14 is included. The flow can be easily changed to an appropriate value.

  Further, in the second embodiment, the delivery means 16 is arranged on the upstream side of the porous member 15. Therefore, even if there is a slight disturbance in the flow of the coolant in the delivery means 16, the disturbance can be attenuated by the porous member 15, so that the measurement accuracy of the conductivity sensor 14 can be kept high.

  In the second embodiment, the sending means 16 is provided on the upstream side of the conductivity sensor 14, but in the present invention, the sending means 16 may be provided on the downstream side of the conductivity sensor 14.

Third Embodiment FIG. 6 is a sectional view of a bypass line of a fuel cell cooling system according to a third embodiment.

  In the lateral passage 24 of the bypass line 20, an air bleeding line 41 branched upward is provided upstream of the conductivity sensor 14. The air vent line 41 is connected to a coolant tank (not shown) having an open portion that can be opened to the atmosphere. The air vent line 41 includes a large diameter portion 41a at the base end portion.

  According to the third embodiment, even if air bubbles flow into the bypass line 20, they are removed through the air vent line 41, so that the air bubbles are less likely to flow into the conductivity sensor 14. Thereby, the reliability of the measurement accuracy of the conductivity sensor 14 is further improved.

  In addition, this invention is not limited only to the above-mentioned embodiment, It can change within the range which does not deviate from the technical idea of this invention.

  The fuel cell cooling system and the structure for measuring the conductivity of the coolant circulation line according to the present invention can improve the measurement accuracy of the conductivity sensor and improve the detection response, and are used in a fuel cell system for vehicles. It can be used not only for household and other stationary fuel cell systems, but has a wide range of uses.

FIG. 1 is a schematic view of a fuel cell cooling system according to a first embodiment of the present invention. 2 is a cross-sectional view of a bypass line of the fuel cell cooling system of FIG. FIG. 3 is an enlarged cross-sectional view of the vicinity of the conductivity sensor of the bypass line of FIG. 4 is a sectional view taken along line IV-IV in FIG. FIG. 5 is a sectional view of a bypass line according to a second embodiment of the present invention. FIG. 6 is a sectional view of a bypass line according to a third embodiment of the present invention.

Explanation of symbols

10 ... Fuel cell cooling system 11 ... Fuel cell stack (fuel cell)
12 ... Radiator (heat radiator)
DESCRIPTION OF SYMBOLS 13 ... Coolant pump 14 ... Conductivity sensor 15 ... Porous member 16 ... Delivery means 20 ... Bypass line 21 ... Upper end (base end part) of downward passage
22 ... Downward passage 23 ... Lower end of downward passage (curved part)
24 ... Sideways passage 25 ... End point (curved part) of sideways passage
26 ... Upward passage 27 ... Upper end of upper passage (confluence)
29 ... Bottom surface of coolant circulation line 31 ... Inner pole 32 ... Outer pole 33 ... Protective tube 35 ... Sensor body 37 ... Through hole 41 Air vent line 41a Large diameter part C ... Center line L (L1, L2, L3) ... Cooling Liquid circulation line

Claims (6)

A coolant circulation line for circulating the coolant,
A fuel cell and a radiator provided in the middle of the coolant circulation line;
A bypass line provided in parallel with a part of the coolant circulation line;
A conductivity sensor that is disposed in the bypass line and that measures the conductivity of a coolant flowing through the bypass line;
A porous member disposed upstream of the conductivity sensor in the bypass line; and
A fuel cell cooling system comprising: The fuel cell cooling system according to claim 1,
A fuel cell cooling system comprising a delivery means for delivering a coolant for the bypass line to the bypass line. The fuel cell cooling system according to claim 2,
The fuel cell cooling system, wherein the delivery means is disposed upstream of the porous member in the bypass line. The fuel cell cooling system according to any one of claims 1 to 3,
The fuel cell cooling system, wherein the bypass line is disposed below a center line of the coolant circulation line. The fuel cell cooling system according to any one of claims 1 to 4,
A fuel cell cooling system comprising an air vent line branched upward from the bypass line upstream of the conductivity sensor. A structure for measuring the conductivity of a coolant in a coolant circulation line in which a fuel cell is interposed,
A bypass line provided in parallel with a part of the coolant circulation line;
A conductivity sensor that is disposed in the bypass line and that measures the conductivity of the coolant flowing through the bypass line;
A porous member disposed upstream of the conductivity sensor in the bypass line; and
A structure for measuring the conductivity of the refrigerant circulation line.

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