JP5155549B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell having a cell stack in which single cells are stacked.

  Conventionally, a unit cell of a polymer electrolyte fuel cell has an MEA (Membrane Electrode Assembly) composed of an electrolyte membrane, an anode (cathode) and a cathode (anode), and further has a pair of separators that sandwich the MEA (for example, , See Patent Document 1). In a fuel cell, a plurality of such single cells are stacked to form a cell stack, and a current collector plate is provided outside the single cells (hereinafter referred to as “end cells”) located at both ends of the cell stack. Insulating plate and end plate are arranged.

  The fuel gas and the oxidizing gas flow from one end of the cell stack to the other end, and are supplied to the fuel gas channel and the oxidizing gas channel of each single cell. Usually, the oxidizing gas is supplied to the cell stack more than the fuel gas and discharged. Due to the electrochemical reaction of both gases, an electromotive force of a single cell is obtained and water is generated on the cathode side. The produced water is drained out of the single cell by the flow of oxidizing gas or fuel gas.

  The heat generated by the electrochemical reaction is exhausted by the refrigerant so that the temperature of the cell stack is maintained at an appropriate operating temperature. Usually, the refrigerant flows from one end of the cell stack to the other end and is supplied to a refrigerant flow path formed between the single cells. A refrigerant channel (hereinafter referred to as “end refrigerant channel”) is also formed between the separator of the end cell and the current collector plate.

  As described in Patent Document 1, there is a fact that the end cell has a lower temperature than other single cells of the cell stack. This is because the end cell is affected by heat radiation from the current collector plate, the insulating plate, and the end plate, and the temperature of the refrigerant in the end refrigerant flow path is lowered. In particular, in the end cell on the total minus side in the cell stack, the temperature on the anode side is lower than the temperature on the cathode side.

  As a result of the temperature difference between the two electrodes, water vapor moves from the oxidizing gas passage to the fuel gas passage, and liquid water is generated in the fuel gas passage. This liquid water is not necessarily drained by the flow of the fuel gas in the fuel gas flow path, but the fuel gas has a smaller energy (flow rate) for draining the liquid water than the oxidizing gas. For this reason, liquid water is not carried away sufficiently, and flooding (excessive wetness) tends to occur in the fuel gas passage on the total minus side. As a result, a phenomenon occurs in which the amount of fuel gas supplied to the end cell on the total minus side decreases, and the voltage of the end cell decreases.

The fuel cell of Patent Document 1 that pays attention to such a temperature decrease of the end cell includes a thin plate-like heating element between the end cell and the current collector plate. The temperature distribution of the cell stack is made uniform by setting the value of the Joule heat of the heating element to a value commensurate with the amount of heat dissipated from both ends of the fuel cell.
JP-A-8-167424

  However, in the fuel cell described in Patent Document 1, since the entire heating element is heated to heat the entire end cell, a large amount of heat and electric power are required. Further, since the temperature of the end cells at both ends is to be raised, the temperature of the end cell on the total plus side may be higher than that of other single cells depending on conditions. In this case, the temperature on the anode side becomes lower than the temperature on the cathode side, and the above-described voltage drop phenomenon that occurs in the end cell on the total minus side also occurs on the end cell on the total plus side.

  An object of the present invention is to provide a fuel cell that can be adjusted efficiently so that the temperature on the anode side in the end cell does not become lower than that on the cathode side, and the voltage drop in the end cell can be suppressed.

  In order to achieve the above object, a fuel cell according to the present invention comprises a cell laminate in which single cells having an anode and a cathode are laminated, and a total negative cell in the cell laminate is cooled from the anode side of the single cell. A refrigerant flow path for supplying the refrigerant to the refrigerant flow path, a refrigerant outlet for discharging the refrigerant from the refrigerant flow path, and a larger amount of heating to the refrigerant outlet side than to the refrigerant inlet side And heating means configured to be.

  According to this configuration, the temperature on the anode side of the total minus side single cell can be raised by the heating means. In addition, due to the relationship between the exothermic reaction of the single cell and the flow of the refrigerant, the temperature difference between the cathode and the anode is larger on the refrigerant outlet side than on the refrigerant inlet side. According to the present invention, since the amount of heating to the refrigerant outlet side is relatively large, the temperature on the anode side can be adjusted efficiently so as not to be lower than that on the cathode side. Therefore, flooding of the single cell on the total minus side can be suppressed, and voltage drop of the single cell can be suppressed. Moreover, since the whole heating is not made uniform, it becomes a small electric power.

  According to a preferred aspect of the present invention, the heating means is configured to heat the refrigerant on the refrigerant outlet side rather than on the refrigerant inlet side. In this case, the refrigerant may be directly heated, or the refrigerant may be indirectly heated, that is, the refrigerant may be heated by heat transfer.

  According to a preferred aspect of the present invention, the heating means is a heating element arranged on the refrigerant outlet side rather than the refrigerant inlet side.

  Thereby, only the refrigerant | coolant exit side can be heated efficiently.

  According to a preferred aspect of the present invention, the fuel cell includes a current collector plate stacked on a single cell on the total minus side, and an insulating plate disposed outside the current collector plate. The heating element is disposed between the current collector plate and the insulating plate.

  Thereby, the anode side of the unit cell on the total minus side can be suitably heated.

  According to a preferred aspect of the present invention, the fuel cell includes a plate having a heating element and sandwiched between a current collector plate and an insulating plate.

  Thereby, for example, even when a compressive load is applied to the entire fuel cell, the heating element can be stably disposed.

  According to a preferred aspect of the present invention, the plate has a first portion provided with a heating element, and a second portion adjacent to the first portion. The first portion is made of a material having a higher thermal conductivity than that of the second portion.

  Thereby, the heat of the heating element can be suitably transferred to the current collector plate, and the anode side on the total minus side can be heated.

  According to a preferred embodiment of the present invention, the heating element is a PTC resistor.

  According to this configuration, the PTC resistor is energized and generates heat at a low temperature on the anode side, so that the temperature on the anode side can be increased. On the other hand, at high temperatures on the anode side, the PTC resistor can be prevented from being energized due to its increased electrical resistance value. By doing so, the PTC resistor does not generate heat, so the temperature on the anode side does not have to be increased more than necessary. Thus, by effectively utilizing the characteristics of the PTC resistor, when flooding is likely to occur, the temperature on the anode side can be raised to suppress flooding, while when it is easy to dry up, it can be suppressed.

  According to a preferred aspect of the present invention, a fuel cell includes a first current collecting plate laminated on a single cell on the total minus side, and a second current laminated on the first current collecting plate via a PTC resistor. Current collector plate. The second current collector plate is configured such that when the PTC resistor can be energized, the current generated by the fuel cell flows through the second current collector plate in parallel with the first current collector plate. .

  According to a preferred aspect of the present invention, the heating means is a refrigerant based on at least one of the temperature of the fuel cell, its output voltage, the temperature of the total negative single cell, its output voltage, and the temperature of the refrigerant. Control the amount of heating.

  Thereby, the temperature on the anode side of the total minus side single cell can be controlled in accordance with various operating states of the fuel cell.

  According to a preferred aspect of the present invention, the total minus-side single cell includes a first separator that supplies fuel gas to the anode and a second separator that supplies oxidizing gas to the cathode. And at least one part of a refrigerant | coolant flow path is formed in a 1st separator.

  Another fuel cell according to the present invention includes a cell stack in which single cells having an anode and a cathode are stacked, and a refrigerant flow for cooling from the anode side of each single cell of the total negative side of the cell stack. A refrigerant, a refrigerant inlet for supplying refrigerant to the refrigerant flow path, a refrigerant outlet for discharging the refrigerant from the refrigerant flow path, and so that the amount of heat released from the refrigerant is smaller on the refrigerant outlet side than on the refrigerant inlet side. Suppression means for suppressing a temperature drop of the refrigerant on the refrigerant outlet side.

  According to this structure, it can suppress efficiently that the temperature of the anode side of the unit cell of a total minus side falls. Thereby, like the above-described fuel cell of the present invention, flooding of single cells on the total minus side can be suppressed, and voltage drop of the single cells can be suppressed.

  According to the fuel cell of the present invention, the temperature on the anode side in the end cell can be adjusted efficiently so as not to be lower than that on the cathode side, and the voltage drop in the end cell can be suppressed.

  Hereinafter, a fuel cell according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings by taking a solid polymer fuel cell suitable for a vehicle as an example. Of course, the fuel cell system including the fuel cell can be mounted not only on a vehicle but also on a self-propelled mobile body such as a ship, an airplane, and a robot, or can be used as a stationary power generation system. .

<First Embodiment>
FIG. 1 is a cross-sectional view of a fuel cell.
The fuel cell 1 has a cell stack 3 formed by stacking single cells 2 that are basic units. The cell stack 3 is formed by stacking a number of single cells 2 of the same type, that is, the same structure. On the outside of the single cells 2 (hereinafter referred to as “end cell 2a” or “end cell 2b”) positioned at both ends of the cell stack 3, current collector plates 5a, 5b, insulating plates 6a, 6b and end plates 7a, 7b are arranged. The fuel cell 1 is given a compressive load in the cell stacking direction. The end cell 2 a is located on the total plus side in the cell stack 3, and the end cell 2 b is located on the total minus side in the cell stack 3.

  The fuel gas, the oxidizing gas, and the refrigerant are supplied from the supply pipe connected to the end plate 7a into the cell stack 3 and flow in the cell stacking direction and in the plane direction of each single cell 2. Thereafter, the fuel gas, the oxidizing gas, and the refrigerant are discharged out of the fuel cell 1 from the discharge pipe connected to the end plate 7a. In FIG. 1, the refrigerant flow is indicated by arrows, and the configuration related to other fluids (fuel gas and oxidizing gas) is omitted.

  Here, the fuel gas means hydrogen gas containing hydrogen. The oxidizing gas means a gas containing an oxidizing agent typified by oxygen or air. The fuel gas and the oxidizing gas may be collectively referred to as a reaction gas. The refrigerant is, for example, cooling water.

FIG. 2 is a cross-sectional view of the single cell 2.
The single cell 2 includes an MEA 20 and a pair of separators 22A and 22B. For example, the MEA 20, the separator 22A, and the separator 22B are integrated by bonding.

  The MEA 20 (membrane-electrode assembly) includes an electrolyte membrane 30 and an anode 32A and a cathode 32B sandwiching the electrolyte membrane 30. The anode 32A and the cathode 32B are composed of a diffusion layer 36 and a catalyst layer 38. The diffusion layer 36 is made of, for example, a porous carbon material. For example, platinum is preferably used as the catalyst of the catalyst layer 38.

  The separators 22A and 22B are made of a gas impermeable conductive material. Examples of the conductive material include carbon, conductive resin, and metals such as aluminum. The separator 22A has a fuel gas channel 40 on the front surface and a refrigerant channel 44A on the back surface. The separator 22B has an oxidizing gas channel 42 on the front surface and a refrigerant channel 44B on the back surface.

  The fuel gas channel 40 supplies the fuel gas to the anode 32A, and the oxidizing gas channel 42 supplies the oxidizing gas to the cathode 32B, thereby causing an electrochemical reaction in the MEA 20. Thereby, the electromotive force of the single cell 2 is obtained. In addition, this electrochemical reaction generates water and generates heat on the cathode 32B side. The refrigerant reduces the heat of the single cell 2 generated by the electrochemical reaction and suppresses the temperature rise of the fuel cell 1.

  One refrigerant flow path 44A of two adjacent single cells 2 and 2 communicates with the other refrigerant flow path 44B, whereby a refrigerant flow path for supplying a refrigerant between the single cells 2 and 2 is formed. Further, a refrigerant flow path 46 is also formed between the end cell 2a and the current collector plate 5a. The refrigerant channel 46 is configured by the refrigerant channel 44B of the separator 22B of the end cell 2a communicating with the refrigerant channel 44C formed in the current collector plate 5a. Further, a coolant channel 48 is also formed between the end cell 2b and the current collector plate 5b. The refrigerant channel 48 is configured by the refrigerant channel 44A of the separator 22A of the end cell 2b communicating with the refrigerant channel 44D formed in the current collector plate 5b. The refrigerant channels 44C and 44D may have the same shape as the refrigerant channels 44A and 44B.

  Here, it can be said that the refrigerant flow path 48 is for cooling the end cell 2b on the total minus side from the anode 32A side. On the other hand, it can be said that the refrigerant flow path formed between the end cell 2b and the single cell 2 adjacent thereto is for cooling the end cell 2b on the total minus side from the cathode 32B side. .

  In another embodiment, the refrigerant flow path 44D may be omitted, and the refrigerant flow path 48 may be configured by only the refrigerant flow path 44A (see, for example, FIG. 11). In another embodiment, a so-called dummy separator that does not flow reactive gas that contributes to power generation may be disposed between the end cell 2b and the current collector plate 5b, and the refrigerant flow path 44D may be formed in the dummy separator. . In any case, at least a part of the coolant channel 48 is constituted by the coolant channel 44A.

  FIG. 3 is a plan view of the separator 22A viewed from the refrigerant flow path 44A side. The shape of the separator 22B is the same as that of the separator 22A, but detailed description and drawings are omitted here.

  The separators 22A and 22B are formed in a rectangular shape in plan view. Each separator 22A, 22B has a peripheral part around the refrigerant flow paths 44A, 44B. An inlet 51a, 52a, 53a on the supply side of the fuel gas, the oxidizing gas, and the refrigerant is formed through one side of the peripheral portion. Further, outlets 51b, 52b, and 53b on the discharge side of the fuel gas, the oxidizing gas, and the refrigerant are formed through the other side that is opposite to the side.

  The refrigerant flow paths 44A and 44B are connected to the refrigerant inlet 53a and the outlet 53b. The refrigerant channels 44A and 44B are supplied with a refrigerant from, for example, a refrigerant inlet 53a located on the lower side in the gravity direction, meander when the refrigerant flows from the lower side to the upper side in the gravity direction, and are discharged from the refrigerant outlet 53b. . Refrigerant flow paths 44A and 44B are constituted by groove-shaped serpentine flow paths having a folded portion in the middle. For example, the fuel gas channel 40 and the refrigerant channel 44A are simultaneously formed on both surfaces of the separator 22A by press molding. The flow paths 42 and 44B on both surfaces of the separator 22B are similarly formed. In addition, you may comprise the refrigerant flow paths 44A and 44B by the several straight flow path where the repetition of an unevenness | corrugation extends in one direction.

  And in the cell laminated body 3, the refrigerant inlet 53a of all the single cells 2 is connected in the lamination direction, and the supply manifold 55 extended in the lamination direction in the cell laminated body 3 is comprised (refer FIG. 1). Moreover, the refrigerant | coolant outlet 53b of all the single cells 2 is connected to the lamination direction, and the discharge manifold 56 extended in the lamination direction in the cell laminated body 3 is comprised (refer FIG. 1).

  Here, in FIGS. 1 and 3, the symbol Wi indicates the flow of the refrigerant in the supply manifold 55, and Wo indicates the flow of the refrigerant in the discharge manifold 56. The symbol wi indicates the flow of the refrigerant between the single cell 2 or the single cells 2 and 2, and wo indicates the flow of the refrigerant between the single cell 2 or the single cells 2 and 2.

  Accordingly, the refrigerant is supplied from outside the fuel cell 1 to the supply manifold 55, and is supplied from the supply manifold 55 to the refrigerant flow path 46 and the refrigerant flow path 48 in addition to the refrigerant flow path between the single cells 2 and 2. Then, the refrigerant that has flowed through these refrigerant flow paths joins at the discharge manifold 56 and is discharged out of the fuel cell 1.

  Although not shown, the fuel cell 1 is incorporated into a fuel cell system including a supply pipe and a discharge pipe corresponding to each fluid. In the fuel cell system, the oxidizing gas is usually pumped to the fuel cell 1 by a compressor, but is humidified during the pumping process. Further, the oxidizing gas is supplied to the fuel cell 1 more than the fuel gas, and a larger amount is discharged.

  Therefore, the oxidizing gas discharged from the fuel cell 1 and the moisture carried away by the fuel gas are more in the oxidizing gas. That is, the fuel cell 1 of the present embodiment is incorporated in a fuel cell system in which the amount of moisture removed from the single cell 2 by the fuel gas is smaller than the amount of moisture removed from the single cell 2 by the oxidizing gas. Strictly speaking, the amount of moisture carried away is calculated in consideration of conditions such as the amount of water produced at the cathode 32B and the ease of movement of moisture from the cathode 32B to the anode 32A via the electrolyte membrane 30. Is.

Next, a heating structure that is a characteristic part of the present invention will be described with reference to FIGS. 1 and 4.
As shown in FIG. 1, the plate 80 is sandwiched between the current collector plate 5b and the insulating plate 6b. However, an insulating sheet 82 is provided between the plate 80 and the current collector plate 5b.

  As shown in FIG. 4, the plate 80 is formed in a rectangular shape in plan view. The size of the plate 80 is approximately the same as or the same as the size of the insulating plate 6b and the separators 22A and 22B. The plate 80 is strong enough not to be deformed by a compressive load when the fuel cell 1 is fastened.

  The plate 80 includes a first portion 92 having a heater 91 and a second portion 93 having no heater 91. The heater 91 (heating means) functions as a heating element by supplying power from a lead wire. The power supply to the heater 91 can be performed by the power generated by the fuel cell 1. The heater 91 is embedded in the first portion 92.

  The first portion 92 is adjacent to the second portion 93. For example, the first portion 92 constitutes the upper half of the plate 80, and the second portion 93 constitutes the lower half of the plate 80. The first portion 92 is made of a material having a higher thermal conductivity than that of the second portion 93. For example, the first portion 92 is made of aluminum, and the second portion 93 is made of a hard resin. By doing so, the insulation between the second portion 93 and the insulating plate 6b and the heat transfer from the second portion 93 to the current collector plate 5b via the insulating sheet 82 are enhanced. Note that the first portion 92 is preferably surface-treated with an insulating material.

  Here, referring to FIG. 3 and FIG. 4, the heater 91 is arranged closer to the outlet 53 b side than the refrigerant inlet 53 a side. That is, the heater 91 is configured to heat the portion near the outlet side 53b side in the refrigerant flow path 48 by heat transfer so that the heating amount to the outlet 53b side is larger than the inlet 53a side. Is done. In FIG. 1, reference numeral 94 indicated by a dotted line in the plate 80 represents an example of a heating region by the heater 91.

  Therefore, when the heater 91 is energized, the heat of the heater 91 is transmitted to the current collector plate 5 b and is transmitted to the refrigerant flowing through the refrigerant flow path 48. This heated refrigerant warms the end cell 2b on the anode 32A side closer to the outlet 53b. In addition, the heat transfer from the contact portion between the current collector plate 5b and the separator 22A of the end cell 2b also warms the side close to the outlet 53b on the anode 32A side of the end cell 2b.

  The effects of the present invention will be described with reference to FIGS.

The “conventional example” shown in FIGS. 5 to 8 means a fuel cell according to a comparative example that does not include the plate 80 of the present invention.
5, 6, and 8, the horizontal axis represents the stack position of the single cell 2 in the cell stack 3, and the horizontal axis in FIG. 7 represents the in-plane position of the end cell 2 b (in-plane position orthogonal to the stack direction). "Inlet side" indicates the inlet 53a side, and "Exit side" indicates the outlet 53b side. On the other hand, the vertical axis in FIGS. 5 and 7 represents the temperature (° C.) of the refrigerant. 6 represents a temperature difference (° C.) obtained by subtracting the refrigerant temperature on the anode 32A side (minus side) from the refrigerant temperature on the cathode 32B side (plus side) in the single cell 2. Furthermore, the vertical axis in FIG. 8 is the amount of water (g / cell) contained in the single cell 2.

  As shown in FIG. 5, in the conventional example, the refrigerant temperature at both ends of the cell stack 3 is lower than that at the center. This is because, as described above, the end cells 2a, 2b are affected by heat radiation from the end plates 7a, 7b, etc., and the temperature of the refrigerant is lowered.

  On the other hand, in the present invention, the end cell 2b side can be heated by the heater 91 described above. Thereby, in this invention, the refrigerant | coolant temperature by the side of the edge part cell 2b is equivalent to the refrigerant | coolant temperature of the single cell 2 of the center part of the cell laminated body 3 (refer curve L1), or becomes higher (curve L2). reference).

  As shown in FIG. 6, in the conventional example, the temperature difference between the refrigerant on the cathode 32 </ b> B side and the anode 32 </ b> A side in the single cell 2 at both ends of the cell stack 3 is larger than that at the center of the cell stack 3. large. This is because in the end cell 2a, the cathode 32B side is affected by heat radiation from the end plate 7a, and in the end cell 2b, the anode side 32A side is affected by heat radiation from the end plate 7b.

  On the other hand, in the present invention, the anode 91A side of the end cell 2b can be heated by the heater 91. Thereby, the temperature of the refrigerant | coolant by the side of the anode 32A of the edge part cell 2b can be raised. Therefore, in the present invention, the refrigerant temperature difference between the two electrodes on the end cell 2b side is equal to the refrigerant temperature difference of the single cell 2 at the center of the cell stack 3 (see curve L3) or lower. (See curve L4).

  In particular, as shown in FIG. 7, in the conventional example, in the end cell 2b, the refrigerant temperature on the anode 32A side and the cathode 32B side is substantially the same on the inlet 53a side, but the temperature difference is large toward the outlet 53b. . This is because the end cell 2b generates heat due to a power generation reaction, and the temperature of the refrigerant on the anode 32A side and the cathode 32B side rises as it goes to the outlet 53b. On the other hand, the anode 32A side is affected by heat dissipation as described above. This is because an increase in the refrigerant temperature on the anode 32A side is suppressed.

  On the other hand, in the present invention, the heater 91 can selectively heat the side close to the outlet 53b on the anode 32A side of the end cell 2b. Thereby, compared with the case where the whole area | region by the side of the anode 32A of the edge part cell 2b is heated, since it becomes the heating area 94 few, it can heat with little electric power. Therefore, the refrigerant temperature on the anode 32A side can be efficiently adjusted on the outlet 53b side of the end cell 2b so as not to be lower than that on the cathode 32B side. The “anode (present invention)” shown in FIG. 7 is an example in which the refrigerant temperature on the anode 32A side is higher than that on the cathode 32B side.

  As shown in FIG. 8, in the conventional example, the water content of the end cell 2 b is larger than that of the other single cells 2 in the cell stack 3. As described above, as a result of the temperature difference in the end cell 2b, liquid water is generated on the anode 32A side (fuel gas flow path 40) of the end cell 2b, but the liquid water is carried away by the fuel gas. It is difficult.

  On the other hand, in the present invention, as shown in FIGS. 5 and 6, in the end cell 2b, it is possible to suppress the occurrence of a temperature difference in which the anode 32A side is at a lower temperature than the cathode 32B side. Thereby, as shown in FIG. 8, the water content of the end cell 2b is equal to the water content of the single cell 2 in the center of the cell stack 3 (see the curve L5) or lower (see FIG. 8). (See curve L6).

  As described above, according to the fuel cell 1 of the present embodiment, the temperature on the anode 32A side of the end cell 2b can be raised with relatively small electric power. Thereby, the temperature on the anode 32A side in the end cell 2b can be adjusted efficiently so as not to be lower than that on the cathode 32B side, and flooding of the end cell 2b can be suppressed. Therefore, the voltage drop of the end cell 2b can be suppressed.

  The heater 91 has a heating start, a heating time, and a heating amount based on at least one of the outside air temperature, the temperature of the fuel cell 1, the temperature of the end cell 2b, and the temperature difference between both electrodes of the end cell 2b. It should be controlled. In particular, the heater 91 preferably generates heat when the temperature is low.

  Here, the temperature of the fuel cell 1 is, for example, the temperature at the refrigerant supply pipe or the temperature at the refrigerant discharge pipe. The temperature of the end cell 2b is, for example, the temperature of the refrigerant in the refrigerant channel 48, and the temperature difference between both electrodes of the end cell 2b is, for example, the temperature of the refrigerant in the refrigerant channel 48 and the end cell. It is a difference with the temperature of the refrigerant | coolant of the refrigerant | coolant flow path 44B between 2b and the single cell 2. FIG.

  Moreover, the heater 91 is good to control a heating start, a heating time, and a heating amount based on the output of the fuel cell 1 and the output of the end cell 2b. In particular, it is preferable that the heater 91 generates heat when the output of the end cell 2b decreases. Further, the heater 91 may generate heat during low load power generation of the fuel cell 1.

Second Embodiment
Next, the fuel cell 1 according to the second embodiment will be described with a focus on the differences with reference to FIGS. 9 and 10. A major difference from the first embodiment is that another heating structure is employed. This heating structure uses a PTC resistor 100 as a heating element instead of the heater 91. In addition, about the structure of 2nd Embodiment which is common in 1st Embodiment, the code | symbol same as 1st Embodiment is attached | subjected and the description is abbreviate | omitted.

As shown in FIG. 10, the PTC resistor 100 generates heat when energized up to a predetermined temperature T ₁ , while the electric resistance value R _PTC suddenly increases when the temperature reaches the predetermined temperature T ₁ , and the PTC resistor 100 _stops energizing. It has a feature that it does not generate heat. The temperature T ₁ is set to, for example, 70 ° C. in consideration of the temperature during power generation of the solid polymer fuel cell 1. Further, the electric resistance value R _PTC is set to 10 R _A at, for example, 0 ° C., and the range is set to, for example, 10 R _{A to} ∞.

  As shown in FIG. 9, the PTC resistor 100 is disposed between the current collector plate 5 b and the second current collector plate 110. Between the current collecting plate 5b and the insulating plate 6b, the PTC resistor 100 and the second current collecting plate 110 are disposed and sandwiched from the refrigerant outlet 53b, while the insulating plate 120 is interposed from the refrigerant inlet 53a. Is placed and clamped.

As shown in FIG. 9, the fuel cell 1 includes an electrical circuit 140 that supplies current to the load 130. In the circuit 140, a portion in which the current collector plate 5b and the correction resistor 141 (electric resistance value R _A ) are connected in series and a portion in which the second current collector plate 110 is provided are connected in parallel to the load 130. The Here, the current flowing through the former part is i _A , the current flowing through the latter part is i _B, and the generated current supplied to the load 130 is I. These relationships can be expressed as follows:

I = i _A + i _B

I _B can be expressed as follows.
i _B = {R _A / (R _A + R _PTC )} × I

Here, as described above, if R _PTC takes a value between 10 R _{A and} ∞, i _B takes a value of 0 to 0.09 × I. In this case, when the temperature is less than 70 ° C., the anode 32A side of the end cell 2b is heated at about 10% of the total generated current I, and not heated above 70 ° C.

According to this embodiment, when the low-load operation and the refrigerant temperature are low (for example, less than 70 ° C.), the generated current of the fuel cell 1 is parallel to the current collecting plate 5b and the PTC resistor 100 and the second current collecting plate 110. , The PTC resistor 100 generates heat and the heater is turned on. Thereby, the effect similar to 1st Embodiment can be acquired. On the other hand, when the refrigerant temperature is high (for example, 70 ° C. or higher), R _PTC of the PTC resistor 100 increases, so that the generated current flows only in the current collector plate 5b.

<Third Embodiment>
Next, the fuel cell 1 according to the third embodiment will be described with reference to FIG. A major difference from the first embodiment is that a suppressing means for suppressing a decrease in temperature is employed instead of the heating structure. In addition, about the structure of 3rd Embodiment which is common in 1st Embodiment, the code | symbol same as 1st Embodiment is attached | subjected and the description is abbreviate | omitted.

  This suppressing means is configured by devising the structure of the current collector plate 5b, the insulating plate 6b, and the end plate 7b described in the first embodiment. Specifically, a through hole 200 is formed in the current collector plate 5 b on the extension of the discharge manifold 56. A flow path 210 communicating with the through hole 200 is formed in the insulating plate 6b, and a flow path 220 communicating with the flow path 210 is formed on the end plate 7b.

  The bypass flow path 230 including the flow path 210 and the flow path 220 is formed to have a folded portion at a position closer to the outlet 53b side than the refrigerant inlet 53a side of the end cell 2b. The bypass channel 230 is connected to a bypass pipe 240 outside the fuel cell 1. The bypass flow path 230 and the bypass pipe 240 flow the refrigerant by bypassing the discharge manifold 56 in the cell stack 3, and this refrigerant is combined with the refrigerant discharged from the discharge manifold 56 outside the fuel cell 1. Merge at point 250.

  According to the present embodiment, a part of the refrigerant whose temperature has risen due to the exothermic reaction of the fuel cell 1 flows into the bypass channel 230. For this reason, in the end cell 2b, the heat radiation amount of the refrigerant is smaller on the outlet 53b side than on the inlet 53a side. Thereby, the temperature fall of the refrigerant | coolant by the side of the exit 53b of the edge part cell 2b can be suppressed, and the temperature fall by the side of the anode 32A of the edge part cell 2b can be suppressed efficiently. Therefore, also in the present embodiment, as in the first embodiment, the flooding of the end cell 2b can be suppressed, and the voltage drop of the end cell 2b can be suppressed.

It is sectional drawing which shows the fuel cell which concerns on 1st Embodiment. It is sectional drawing of the single cell of the fuel cell which concerns on 1st Embodiment. It is a top view of the separator of the single cell concerning a 1st embodiment. It is a top view of the plate provided with the heating means which concerns on 1st Embodiment. It is a graph which shows a prior art example and this embodiment about the relationship between the lamination position of a single cell, and refrigerant | coolant temperature. It is a graph which shows a prior art example and 1st Embodiment about the relationship between the lamination position of a single cell, and the temperature difference between the poles in a single cell. It is a graph which shows a prior art example and 1st Embodiment about the relationship between the position in the cell surface of the edge part cell of a total minus side, and the refrigerant | coolant temperature of an anode side and a cathode side. It is a graph which shows a prior art example and 1st Embodiment about the relationship between the lamination | stacking position of a single cell, and the water content of a single cell. It is sectional drawing which shows the fuel cell which concerns on 2nd Embodiment. It is a graph which shows the characteristic of the PTC resistor which concerns on 2nd Embodiment. It is sectional drawing which shows the fuel cell which concerns on 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Single cell, 2a ... Total positive side end cell, 2b ... Total negative side end cell, 3 ... Cell laminated body, 5a, 5b ... Current collecting plate, 6a, 6b ... Insulating plate 7a, 7b ... end plate, 20 ... MEA, 22A ... separator, 22B ... separator, 32A ... anode, 32B ... cathode, 40 ... fuel gas passage, 42 ... oxidizing gas passage, 44A, 44B, 44C, 44D, 46, 48 ... refrigerant flow path, 53a ... refrigerant inlet, 53b ... refrigerant outlet, 80 ... plate, 91 ... heater (heating means, heating element), 92 ... first part, 93 ... second part, 100 ... PTC Resistor, 110 ... second current collector plate, 230 ... bypass channel (suppressing means)

Claims (11)

A cell laminate in which single cells having an anode and a cathode are laminated;
A refrigerant channel for cooling the single cell located at the end of the cell stack from the outside of the single cell;
A refrigerant inlet for supplying a refrigerant to the refrigerant flow path;
A refrigerant outlet for discharging the refrigerant from the refrigerant flow path;
In a fuel cell comprising
Heating means configured to increase the amount of heating to the refrigerant outlet side more than the refrigerant inlet side is further provided on the total minus side of the cell stack, while the total plus side of the cell stack Does not have a fuel cell.   The fuel cell according to claim 1, wherein the heating unit is configured to heat the refrigerant on the refrigerant outlet side rather than on the refrigerant inlet side.   3. The fuel cell according to claim 1, wherein the heating unit is a heating element arranged closer to the refrigerant outlet side than to the refrigerant inlet side. Current collectors stacked on the total minus side single cell;
An insulating plate disposed outside the current collector plate;
Further comprising
The fuel cell according to claim 3, wherein the heating element is disposed between the current collector plate and the insulating plate.   The fuel cell according to claim 4, further comprising a plate having the heating element, the plate being sandwiched between the current collector plate and the insulating plate. The plate has a first portion where the heating element is provided, and a second portion adjacent to the first portion,
The fuel cell according to claim 5, wherein the first portion is made of a material having a higher thermal conductivity than the second portion.   The fuel cell according to claim 3, wherein the heating element is a PTC resistor. A first current collecting plate laminated on the total minus side single cell;
A second current collecting plate laminated on the first current collecting plate via the PTC resistor, and when the PTC resistor can be energized, the current generated by the fuel cell is the first current collecting plate. A second current collector plate configured to flow through the second current collector plate in parallel with the current collector plate;
The fuel cell according to claim 7, comprising:   The heating means controls the heating amount based on at least one of a temperature of the fuel cell, an output voltage thereof, a temperature of the total negative single cell, an output voltage thereof, and a temperature of the refrigerant. Item 9. The fuel cell according to any one of Items 2 to 8. The negative unit cell has a first separator that supplies fuel gas to the anode, and a second separator that supplies oxidizing gas to the cathode.
The fuel cell according to any one of claims 1 to 9, wherein at least a part of the refrigerant flow path is formed in the first separator. A cell laminate in which single cells having an anode and a cathode are laminated;
A refrigerant channel for cooling the single cell located at the end of the cell stack from the outside of the single cell;
A refrigerant inlet for supplying a refrigerant to the refrigerant flow path;
A refrigerant outlet for discharging the refrigerant from the refrigerant flow path;
In a fuel cell comprising
The cell stack is further provided with suppression means on the total minus side of the cell stack so that the amount of heat released from the refrigerant is smaller on the refrigerant outlet side than on the refrigerant inlet side. On the other hand, a fuel cell not provided on the total positive side of the cell stack .

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