JP2005347189A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system in which a differential pressure between electrodes can be reduced by an effective utilization of a regulator that introduces pressurized gas as a signal pressure into a pressure regulation room. <P>SOLUTION: This regulator 40 has the pressure regulation room 57 into which more pressurized gas than that of the standard pressure is introduced. The regulator 40 adjusts a secondary side pressure of the fuel gas supplied to the fuel cell 2 because a degree of opening of a valve body 55 is adjusted in accordance with the secondary side pressure of the fuel gas and the pressure of the pressurized gas which acts on a diaphragm 56, and in accordance with an energizing force of an energizing member 62 that energizes the valve body 55 connected to the diaphragm 56 toward a direction to close the valve. Then, at the standard pressure state which is for instance atmospheric pressure state where the pressure of the pressured gas is not introduced into the pressure regulation room 57, opening characteristics of the valve body 55 are settled so that a region will exist where a gas flow amount becomes zero by closing of the valve body 55 in a gas supply flow area supplying the gas to the fuel cell 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system in which the pressure of fuel gas is adjusted by a regulator and supplied to a fuel cell.

  A solid polymer electrolyte fuel cell mounted on a fuel cell vehicle has an anode (fuel electrode) and a cathode (air electrode) on both sides of the electrolyte membrane, and a fuel gas typified by hydrogen gas is supplied to the anode. In addition, electricity is taken out by supplying an oxidizing gas typified by air to the cathode. In general, the fuel gas is stored in, for example, a high-pressure tank, adjusted to a predetermined pressure by a regulator, and supplied to the anode. On the other hand, the oxidizing gas is supplied to the cathode when air in the atmosphere is pumped by the compressor. In the fuel cell, in order to prevent damage to the electrolyte membrane, it is necessary to prevent the pressure difference between the anode-side fuel gas pressure and the cathode-side oxidizing gas pressure from being excessive.

  A curve L1 in FIG. 4 shows the flow rate characteristic of the regulator with respect to the flow rate of the fuel gas. The secondary pressure of the regulator (that is, the fuel gas pressure on the anode side) tends to drop slightly as the flow rate increases, but is set to a positive pressure higher than the atmospheric pressure P over the entire supply flow rate range. . A curve L2 indicates the discharge characteristic of the compressor with respect to the flow rate of the oxidizing gas, and the discharge pressure of the compressor (that is, the oxidizing gas pressure on the cathode side) gradually increases as the flow rate increases.

  As is clear from FIG. 4, the inter-electrode differential pressure varies according to the load of the fuel cell (the flow rate of fuel gas or oxidizing gas supplied to the fuel cell). In general, a fuel cell is frequently used at a low load. However, as shown in FIG. 4, the inter-electrode differential pressure increases at the low load, and it is easy to promote breakage of the electrolyte membrane. It is conceivable to set the flow rate characteristics of the regulator as a whole lower in order to simply grasp this problem and reduce the pressure difference between the electrodes at a low load.

  However, for example, in a fuel cell system in which the fuel off-gas discharged from the fuel cell is circulated again to the fuel cell by the pump, the flow rate per pump rotation speed decreases. It becomes necessary to raise, and efficiency is deteriorated. Further, when the fuel cell is under a high load, the flow rate of the fuel gas may be insufficient.

Therefore, in order to reduce the inter-electrode differential pressure at a low load and ensure the flow rate of fuel gas at a high load, it is conceivable to operate a regulator using the discharge pressure of the compressor (for example, Patent Document 1). reference.). Specifically, not the atmospheric pressure but the oxidizing gas pressure, which is the discharge pressure of the compressor, is directly introduced into the regulator's pressure adjustment chamber, so that the pressure difference between the oxidizing gas pressure and the fuel gas pressure (extremely) Actuate the regulator based on the differential pressure.
JP 2003-68334 A (page 4 and FIG. 1)

  A curve L3 in FIG. 4 shows a combined flow rate characteristic of the regulator when the discharge pressure of the compressor having the discharge characteristic of the curve L2 is introduced into the pressure regulating chamber of the regulator having the flow rate characteristic of the curve L1. As shown by the curve L3, when the discharge pressure of the compressor is simply introduced into the pressure regulating chamber of the regulator that is set to operate properly under atmospheric pressure, the secondary that is finally adjusted by the regulator. The fuel gas pressure on the side becomes very high, and on the contrary, the pressure difference between the electrodes is increased.

  The present invention has been made paying attention to the flow rate characteristics of a regulator, and an object of the present invention is to provide a fuel cell system capable of appropriately reducing the inter-electrode differential pressure by effectively utilizing the regulator. .

  The fuel cell system of the present invention is configured such that the inner space of the housing is partitioned by a diaphragm to which a valve body is connected, and the fuel gas supplied to the fuel cell can flow from the primary side to the secondary side. And the other space is provided with a regulator configured as a pressure regulating chamber into which a gas pressurized from a reference pressure is introduced. The regulator includes a secondary pressure of fuel gas acting on the diaphragm and a pressure of the pressurized gas. The secondary pressure of the fuel gas supplied to the fuel cell is adjusted by adjusting the opening of the valve body according to the pressure and the biasing force of the biasing member that biases the valve body in the valve closing direction. The regulator has a valve opening characteristic of the valve body so that there is a region in which the flow rate of the fuel gas is supplied to the fuel cell and the flow rate of the fuel gas is closed and the flow rate is zero. Is set.

According to this configuration, the regulator in the case where the pressure regulating chamber is in the non-pressurized reference pressure state has the zero flow rate region that blocks the flow of the fuel gas to the secondary side in the supply flow rate region. By introducing the pressure of the gas pressurized from the reference pressure into the pressure chamber, the flow of the fuel gas to the secondary side is allowed and the secondary pressure of the fuel gas is adjusted. In this adjustment, the degree of opening of the valve body connected to the diaphragm depends on the balance between the secondary pressure of the fuel gas acting on the diaphragm and the pressure of the pressurized gas in the pressure adjusting chamber and the biasing force of the biasing member. This is done by mechanical adjustment.
In this way, there is a region where the flow rate is zero in the fuel gas supply flow rate region in the reference pressure state, instead of setting the fuel gas to flow in the entire range of the supply flow rate region in the reference pressure state of the pressure regulating chamber. By setting the valve opening characteristics of the valve body so that the pressure of the gas pressurized higher than the reference pressure is introduced into the pressure regulating chamber, the increase range of the secondary pressure of the fuel gas set to be increased Can be small. That is, by setting the flow rate characteristic of the regulator within a range where it is difficult to use in the reference pressure state, the increase in the secondary pressure in the above-described combined flow rate characteristic of the regulator is suitably suppressed.
Here, the “pressurized gas” may be, for example, an oxidant gas pressurized by a compressor provided in an oxidant gas supply system of the fuel cell, or may be pressurized by another pressure source (air pump). Air may be used. When the former oxidizing gas is used, the differential pressure between the electrodes can be suitably suppressed.
The “reference pressure” is, for example, atmospheric pressure. When a region where the flow rate is zero is set only in a part of the supply flow rate region in the “reference pressure state”, the flow characteristics of the regulator permit the fuel gas flow when the supply flow rate region is small. Become. That is, by setting in this way, when the pressurized gas is the above-described oxidizing gas, the regulator can be used even at the start of the fuel cell system in which the oxidizing gas is difficult to be quickly introduced into the pressure adjusting chamber. Since the flow of the fuel gas to the secondary side is allowed, the startability of the fuel cell system can be improved.

  In this case, it is preferable that the point of transition to a region where the flow rate becomes zero exists in a flow rate region that is at least half of the maximum supply flow rate in the supply flow rate region.

  According to this configuration, the regulator generally has a pressure characteristic (hysteresis) that changes the secondary side pressure when the primary side pressure changes. However, by setting the regulator as described above, the supply flow rate of the fuel gas can be increased. Accordingly, it is possible to appropriately cope with the primary pressure that can change accordingly.

  In another fuel cell system of the present invention, the inner space of the housing is partitioned by a diaphragm to which a valve body is connected, and in one space, the fuel gas supplied to the fuel cell can flow from the primary side to the secondary side And the other space is provided with a regulator configured as a pressure regulating chamber into which a gas pressurized from a reference pressure is introduced. The regulator is pressurized with the secondary pressure of the fuel gas acting on the diaphragm. The secondary pressure of the fuel gas supplied to the fuel cell is adjusted by adjusting the opening of the valve body according to the pressure of the gas and the biasing force of the biasing member that biases the valve body in the valve closing direction. In the regulator, the valve opening characteristic of the valve body is set so that the secondary pressure of the fuel gas increases as the flow rate of the fuel gas increases.

According to this configuration, when the gas pressurized from the reference pressure is introduced into the pressure regulating chamber, the secondary pressure of the fuel gas acting on the diaphragm, the pressure of the pressurized gas in the pressure regulating chamber, and the urging member The opening degree of the valve body connected to the diaphragm is mechanically adjusted by the balance with the urging force, and the secondary pressure of the fuel gas is adjusted. At this time, since the valve opening characteristic of the valve body is set so that the secondary pressure of the fuel gas increases as the flow rate of the fuel gas increases, the change in the fuel gas pressure on the anode side in the fuel cell with the increase in the flow rate Can correspond to a change in the oxidizing gas pressure on the cathode side as the flow rate increases. Thereby, it is possible to appropriately reduce the inter-electrode differential pressure over a wide range of the supply flow rate region.
Here, as described above, the “pressurized gas” can be composed of an oxidizing gas or the like supplied to the fuel cell, and the “reference pressure” is, for example, atmospheric pressure.

  In these cases, it is preferable that the setting element for setting the valve opening characteristic of the valve body includes the property of the urging member.

  According to this configuration, for example, the valve opening characteristic of the valve element can be set as described above by setting a property such as a spring constant of the biasing member to a predetermined value.

  In these cases, it is preferable that the setting element for setting the valve opening characteristic of the valve body includes the properties of the diaphragm.

  According to this configuration, for example, the valve opening characteristic of the valve body can be set as described above by setting the properties such as the pressure receiving area of the diaphragm to a predetermined value.

  In these cases, it is preferable that a pressure regulating valve for regulating the pressure of the pressurized gas introduced into the pressure regulating chamber is provided on the upstream side of the pressure regulating chamber.

  According to this configuration, since the pressurized gas regulated by the pressure regulating valve is introduced into the pressure regulating chamber, the composite flow rate characteristic can be suitably reduced.

  In these cases, it is preferable that an accumulator for temporarily storing the pressurized gas introduced into the pressure regulating chamber is provided on the upstream side of the pressure regulating chamber.

  According to this configuration, since the pressure of the pressurized gas is stabilized by the accumulator, it is possible to make it difficult for a sudden pressure fluctuation of the pressurized gas acting on the pressure adjusting chamber to occur.

  According to the fuel cell system of the present invention, the pressure difference between the electrodes is appropriately reduced by the regulator having a predetermined flow rate characteristic, so that damage to the electrolyte membrane or the like of the fuel cell can be appropriately suppressed. In addition, the reliability of the entire system can be improved.

  Hereinafter, a fuel cell system according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In this fuel cell system, the pressure of the gas pressurized into the pressure regulating chamber of the regulator is introduced as a signal pressure, and the fuel gas whose pressure is adjusted by the regulator is supplied to the fuel cell. By setting the flow rate characteristic to a predetermined value, the inter-electrode differential pressure in the fuel cell is appropriately reduced. Hereinafter, a solid polymer electrolyte type fuel cell will be described as an example of a fuel cell suitable for a fuel cell vehicle represented by a device equipped with a fuel cell system.

  As shown in FIG. 1, a fuel cell system 1 includes a solid polymer electrolyte type fuel cell 2 that generates electric power upon receiving supply of oxygen gas (air) as an oxidizing gas and hydrogen gas as a fuel gas, An oxygen gas supply system 3 that supplies oxygen gas to the battery 2, a hydrogen gas supply system 4 that supplies hydrogen gas to the fuel cell 2, and a control device (ECU) that controls the entire system including components of each of these supply systems And. The fuel cell 2 is configured as a stack structure in which a large number of single cells serving as basic units are stacked. Although not shown in the figure, each single cell is composed of an electrolyte membrane made of an ion exchange membrane and a pair of electrodes (anode and cathode) sandwiching the electrolyte membrane from both sides.

  Oxygen gas having a predetermined pressure is supplied to the cathode by an oxygen gas supply system 3, and hydrogen gas having a predetermined pressure is supplied to the anode by a hydrogen gas supply system 4. As will be described later, the pressure difference between the pressure of the oxygen gas on the cathode side and the pressure of the hydrogen gas on the anode side (differential pressure difference) should not be excessive regardless of the load (power generation amount) of the fuel cell 2. It is set low. In the fuel cell 2, power is generated by an electrochemical reaction between oxygen gas and hydrogen gas, and a fuel cell vehicle equipped with the fuel cell system 1 travels using the power generated by the fuel cell 2.

  The oxygen gas supply system 3 includes a supply flow channel 11 for supplying oxygen gas to the fuel cell 2, a discharge flow channel 12 for discharging oxygen off-gas discharged from the fuel cell 2 to the outside, and the pressure of the oxygen gas. And a pressure adjusting system 13 that guides to a regulator 40 described later. The supply flow path 11 includes a compressor 16 that takes in oxygen gas in the atmosphere via a filter 15, and a humidifier 17 that is provided on the downstream side of the compressor 16 and humidifies oxygen gas pumped by the compressor 16. It is installed.

  The humidifier 17 is also disposed on the discharge channel 12 and exchanges moisture between the purified oxygen gas and the oxygen off gas. A back pressure adjusting valve 18 that adjusts the pressure of oxygen gas in the fuel cell 2 by adjusting the flow rate of oxygen off-gas is disposed in the discharge flow path 12 between the humidifier 17 and the fuel cell 2. . The opening degree of the back pressure adjusting valve 18 is adjusted by the control device in accordance with the load of the fuel cell 2.

  The compressor 16 has a motor connected to the control device, and the rotational speed of the motor is controlled according to the load of the fuel cell 2. For example, when the fuel cell 2 shifts from a low load at the time of starting the fuel cell vehicle to a high load at the time of acceleration, the compressor 16 increases the rotation speed of the motor and increases the amount of oxygen gas supplied to the fuel cell 2. . At this time, as shown in the discharge characteristic curve L2 of the compressor 16 with respect to the flow rate of oxygen gas in FIG. 3, the discharge pressure of the compressor 16 (oxygen gas inlet pressure of the fuel cell 2) increases with the increase in the flow rate of oxygen gas. Rise gradually.

  The pressure adjustment system 13 has a branch channel 21 branched and connected to the supply channel 11 on the upstream side of the humidifier 17, and the branch channel 21 dilutes the oxygen gas pumped by the compressor 16 and the regulator 40. Guide to vessel 36. Since the branch flow path 21 is branched from the supply flow path 11 on the upstream side of the humidifier 17, the corrosion of the regulator 40 is preferably suppressed as compared with the case where the branch flow path 21 is branched on the downstream side of the humidifier 17. The branch channel 21 is provided with an upstream control valve 22 that regulates the pressure of oxygen gas, an accumulator 23 (buffer tank) that is provided downstream of the upstream control valve 22 and temporarily stores oxygen gas, and an accumulator. And a downstream side control valve 24 that regulates the pressure of oxygen gas.

  The accumulator 23 stabilizes the pressure of the oxygen gas regulated by the upstream control valve 22. The pressure of the oxygen gas stored in the accumulator 23 is higher than atmospheric pressure. The upstream side control valve 22 and the downstream side control valve 24 are pressure control valves that control the opening degree of the valve, and are configured by, for example, a mechanical regulator. A branch passage 21 between the accumulator 23 and the downstream control valve 24 is branched to a pressure introduction passage 25 for introducing the pressure of oxygen gas stabilized by the accumulator 23 into the regulator 40 as a signal pressure. ing. As will be described later, the regulator 40 adjusts the pressure of the hydrogen gas supplied to the fuel cell 2 based on the pressure of the oxygen gas and the like.

  The hydrogen gas supply system 4 is discharged from the fuel cell 2, a hydrogen supply source 31 such as a high-pressure tank that stores high-pressure hydrogen gas, a supply channel 32 that supplies the hydrogen gas from the hydrogen supply source 31 to the fuel cell 2, and the hydrogen cell. A circulating flow path 33 for returning the hydrogen off gas (unreacted hydrogen gas) to the supply flow path 32, a hydrogen pump 34 for returning the hydrogen off gas in the circulation flow path 33 to the supply flow path 32, and a downstream of the hydrogen pump 34. Provided in the circulation path 33 on the side, a check valve 35 for preventing the back flow of the hydrogen off gas, and a discharge pipe 37 branched to the circulation path 33 to guide impurities in the hydrogen off gas to the diluter 36 together with the hydrogen off gas. And have.

  The hydrogen pump 34 is driven and controlled by a control device according to the load of the fuel cell 2. The circulation channel 33 is connected to the junction A of the supply channel 32, and a mixed gas composed of new hydrogen gas and hydrogen off-gas that merged at the junction A is supplied to the fuel cell 2. The discharge flow path 37 is provided with a purge valve 38 that functions as a shut valve that opens and closes the discharge flow path 37. The purge valve 38 that is controlled to be opened and closed by the control device is appropriately opened when the fuel cell system 1 is operating, so that the hydrogen off-gas is led to the diluter 36 through the discharge passage 37. In the diluter 36, the concentration of this hydrogen off gas is reduced using the oxygen gas from the branch flow path 21. The exhaust gas treated by the diluter 36 is finally exhausted into the atmosphere outside the system through the exhaust passage 39 and finally joined with the oxygen off-gas in the exhaust passage 12.

  The regulator 40 for adjusting the pressure of the hydrogen gas supplied to the fuel cell 2 is disposed on the upstream side of the confluence point A of the supply flow path 32. Although not shown, on the upstream side of the regulator 40 in the supply flow path 32, a shut valve and various pressure sensors are disposed in addition to a plurality of regulators for reducing the pressure of the hydrogen gas from the hydrogen supply source 31. . That is, in the present embodiment, hydrogen gas decompressed by a plurality of regulators flows into the regulator 40 in the figure, and the hydrogen gas that has passed through the regulator 40 merges with the hydrogen off-gas and is supplied to the fuel cell 2. The inlet pressure of the hydrogen gas of the fuel cell 2 is adjusted by the regulator 40.

  For example, the regulator 40 may be configured as a poppet type as shown in FIG. As shown in FIG. 2, the regulator 40 has an outer shell constituted by a housing 51, and the housing 51 includes a primary-side inlet 52 connected to a hydrogen gas supply channel 32 and a secondary-side flow. An outlet 53 and an inlet 54 connected to the oxygen gas pressure introducing passage 25 are formed.

  The internal space of the housing 51 is partitioned up and down by a diaphragm 56 to which a valve body 55 is connected, and the space above these is configured as a flow path through which hydrogen gas can flow from the primary side to the secondary side. The lower space is configured as a pressure regulating chamber 57 into which oxygen gas is introduced from the introduction port 54. A secondary pressure of hydrogen gas acts on the upper surfaces of the valve body 55 and the diaphragm 56, and a pressure of oxygen gas introduced into the pressure regulating chamber 57 acts on the lower surfaces of the valve body 55 and the diaphragm 56. The regulator 40 adjusts the inlet pressure of the hydrogen gas of the fuel cell 2 that is the secondary side pressure by introducing the oxygen gas of the pressure adjusting system 13 into the pressure regulating chamber 57.

  A pressure adjusting spring 58 that urges the valve body 55 in the valve opening direction (upward) is disposed in the pressure adjusting chamber 57. The pressure adjusting spring 58 has a predetermined property such as a spring constant. The valve body 55 is provided with a poppet 60 through a stem 59, and the side surface of the poppet 60 is configured to be detachable from a valve seat 61 provided in the housing 51. In a state where the valve body 55 in which the poppet 60 is separated from the valve seat 61 is opened, the flow path between the primary side and the secondary side is in communication and the flow of hydrogen gas to the secondary side is allowed. On the other hand, in a state where the valve element 55 in which the poppet 60 contacts the valve seat 61 is closed, the flow path between the primary side and the secondary side is blocked, and the flow of hydrogen gas to the secondary side is blocked. .

  Between the upper surface of the poppet 60 and the housing 51, a pressure regulating spring 62 (biasing member) that biases the valve body 55 in the valve closing direction (downward) via the poppet 60 is disposed. The pressure adjusting spring 62 is disposed coaxially with the pressure adjusting spring 58 and the stem 59, and the properties such as the spring constant are set to a predetermined value like the pressure adjusting spring 58. With such a configuration, the regulator 40 is responsive to the pressure of the oxygen gas and the secondary pressure of the hydrogen gas acting on the valve body 55 and the diaphragm 56 and the biasing force of the pressure regulating spring 58 and the pressure regulating spring 62. The secondary pressure of the hydrogen gas is adjusted by adjusting the opening degree of the valve body 55 (position of the poppet 60).

  As described above, the pressure regulating chamber 57 of the regulator 40 is supplied with a pressurized oxygen gas pressure higher than the atmospheric pressure serving as the reference pressure, but is in an atmospheric pressure state where this oxygen gas is not introduced ( In the reference pressure state), the valve opening characteristic of the valve body 55 is set so as to satisfy the following regulations. That is, the regulator 40 of the present embodiment is configured such that when the pressure regulating chamber 57 is in the atmospheric pressure state, there is a region where the valve body 55 is closed and the flow rate becomes zero in the hydrogen gas supply flow rate region to the fuel cell 2. The valve opening characteristic of the body 55 is set.

  This point will be described in detail with reference to FIGS. 3 and 4 mainly showing the valve opening characteristics of the regulator 40 (that is, the secondary pressure characteristics with respect to the flow rate). The elements that set the valve opening characteristics of the valve body 55 are as follows. For example, in addition to these properties typified by material characteristics such as the pressure receiving area, shape, and rigidity of the valve body 55 and the diaphragm 56, the shape, material properties, and spring constant of the pressure regulating spring 58 and pressure regulating spring 62 are representative. These properties are included. That is, the valve opening characteristic of the valve body 55 can be set by changing the property selected from at least one of these pressure receiving areas, shapes, material characteristics, and spring constants.

  A curve L1 in FIGS. 3 and 4 shows the flow rate characteristic of the regulator 40 with respect to the flow rate of the hydrogen gas when the pressure regulating chamber 57 is in the atmospheric pressure state. The secondary side set pressure in the regulator 40 generally decreases with an increase in the flow rate of hydrogen gas. The secondary side pressure that has decreased is the inlet pressure of the hydrogen gas in the fuel cell 2 with respect to the hydrogen gas flow rate. It becomes. In order to allow the flow of hydrogen gas to the secondary side in the whole range of the supply flow rate region of hydrogen gas in the pressure adjusting chamber 57 in the atmospheric pressure state, as shown by a curve L1 in FIG. It is necessary to set the valve opening characteristic of the valve body 55 so that the secondary pressure becomes higher than the atmospheric pressure P.

  On the other hand, the regulator 40 of this embodiment has the flow rate characteristic of the curve L1 shown in FIG. 3 which lowered the characteristic as a whole from the curve L1 of FIG. In the regulator 40 having this flow rate characteristic, the secondary side pressure is in a positive pressure range that allows the hydrogen gas to flow to the secondary side, and the secondary side pressure that has dropped with the increase in the hydrogen gas flow rate is the secondary side. The valve opening characteristic of the valve body 55 is set so as to include a negative pressure range that blocks the flow of hydrogen gas to the valve. Therefore, the regulator 40 allows the flow of hydrogen gas only up to the flow rate F if the pressure regulating chamber 57 is used in an atmospheric pressure state, and after the flow rate F, the valve body 55 is closed and the flow of hydrogen gas is allowed to flow. Cut off.

  A curve L3 in FIG. 3 shows a combined flow rate characteristic of the regulator 40 of the present embodiment. That is, when the oxygen gas from the compressor 16 having the discharge characteristic of the curve L2 in FIG. 3 is introduced into the pressure regulating chamber 57 of the regulator 40 having the flow characteristic of the curve L1 in FIG. The secondary side pressure finally adjusted is shown. As shown by this curve L3, the regulator 40 allows the flow of hydrogen gas even after the flow rate F, and therefore allows the flow of hydrogen gas to the secondary side in the entire range of the supply flow rate of hydrogen gas and the hydrogen gas. Adjust the secondary pressure of the gas. Further, as shown by the curve L3, the regulator 40 of the present embodiment is set to the valve opening characteristic of the valve body 55 so that the secondary pressure of the hydrogen gas increases as the flow rate of the hydrogen gas increases.

  As described above, according to the fuel cell system 1 of the present embodiment, there is a region where the flow rate of hydrogen gas is zero in the supply flow rate region in an atmospheric pressure state where oxygen gas is not introduced into the pressure regulating chamber 57. The flow characteristic of the regulator 40 is set intentionally. As a result, the oxygen gas pressure is actually introduced into the pressure regulating chamber 57 as compared with the case where the flow rate characteristic is set to ensure the hydrogen gas flow in the entire supply flow rate range in the atmospheric pressure state (in the case of FIG. 4). Thus, it is possible to reduce the increase width of the secondary pressure of the regulator 40 that rises in the above state.

  Thereby, while being able to reduce appropriately the pressure difference between electrodes in low load, the flow volume of hydrogen gas in high load can be ensured appropriately. Further, since the change in the secondary pressure of hydrogen gas (hydrogen gas inlet pressure of the fuel cell 2) accompanying the increase in flow rate corresponds to the slope of the change in the inlet pressure of oxygen gas in the fuel cell 2 accompanying the increase in flow rate, The inter-electrode differential pressure can be appropriately reduced over a wide range of the supply flow rate region.

  Further, in the regulator 40 of the present embodiment, the secondary pressure is set to a positive pressure range that allows the flow of hydrogen gas to the secondary side in a small flow rate range (a flow rate range smaller than the flow rate F in FIG. 3). Therefore, the regulator 40 can allow the hydrogen gas to flow to the secondary side when starting the fuel cell system 1 in which oxygen gas is not easily introduced into the pressure regulating chamber 57 quickly. Thereby, the startability of the fuel cell system 1 can be improved. In this case, the secondary side set pressure of the regulator 40 may be set in a positive pressure range so that the startability of the fuel cell system 1 can be ensured, but the change in the primary side pressure of the regulator 40 is taken into consideration. Is preferably set.

  For example, the valve opening characteristic of the valve body 55 is set so that the point (flow rate F in FIG. 3) at which the flow rate becomes zero exists in a flow rate range that is at least half of the maximum supply flow rate in the supply flow rate range. You only have to set it. Thereby, it is possible to appropriately cope with the primary pressure that can change according to the supply flow rate of the hydrogen gas.

  It should be noted that the secondary pressure can be set to a negative pressure range in the entire flow rate range of the regulator 40, and in such a case, the regulator 40 is in the supply flow rate range in the atmospheric pressure state of the pressure regulating chamber 57. In the entire range, the flow of hydrogen gas to the secondary side is cut off. In this case, the supply of hydrogen gas may be started after the supply of oxygen gas to the fuel cell 2 when the fuel cell system 1 is started.

  In addition, although the oxidizing gas pressurized by the compressor 16 is used as the gas to be introduced into the pressure regulating chamber 57, for example, air pressurized by another pressurizing source (air pump) or the like, for example, from a reference pressure that is atmospheric pressure. Any highly pressurized gas may be used. However, the differential pressure between the electrodes can be suitably reduced by using the oxidizing gas pressurized by the compressor 16 as in the present embodiment.

  By the way, the fuel cell vehicle equipped with the fuel cell system 1 travels in various usage environments, but the fuel cell system 1 described above is also useful when traveling in high altitudes, for example. At high altitude, the atmospheric pressure is lowered by about a predetermined pressure (10 to 20 kPa), but in this embodiment, the oxygen gas taken in by the compressor 16 as described above is regulated as a pressure adjusted by the upstream control valve 22, the accumulator 23, or the like. Therefore, the regulator 40 of this embodiment is not affected by changes in atmospheric pressure. Therefore, even when the fuel cell vehicle travels at a high altitude, the pressure of the hydrogen gas supplied to the fuel cell 2 can be stably set by the regulator 40. Further, when the upstream side control valve 22 and the downstream side control valve 24 are composed of electromagnetic valves whose opening degree is controlled by the control device, the upstream side control valve 22 and the downstream side control valve 22 You may adjust the opening degree of the downstream control valve 24, respectively.

  This embodiment is premised on reducing the pressure difference (electrode pressure difference) between the anode side and the cathode side of the single cell, preferably by introducing a part of the oxidizing gas into the pressure regulating chamber 57 of the regulator 40. To do. However, when the pressurized oxidizing gas is directly introduced into the pressure regulating chamber 57, the pressure difference between the electrodes increases conversely (see FIG. 4). Therefore, in order to cope with this, in the present embodiment, the valve opening characteristic of the regulator 40 is previously set to be an oxidizing gas pressurized under a reference pressure state (preferably a pressure state in which the pressurized oxidizing gas is not introduced or an atmospheric pressure state). Is set in anticipation of being introduced.

  Specifically, the valve opening characteristics of the regulator 40 are set such that a gas supply region and a supply restriction region where the gas supply flow rate becomes zero exist under the reference pressure state. From another viewpoint, this is a characteristic in which the secondary pressure characteristic of the regulator 40 has a high region and a low region with respect to the reference pressure under the reference pressure state. Preferably, the characteristics of the secondary pressure of the regulator 40 are set higher than the reference pressure in the small gas flow rate region (the flow rate region smaller than F in FIG. 3), and the large gas flow rate region (the flow rate larger than F in FIG. 3). In the area), it is set lower than the reference pressure.

It is a block diagram which shows the structure of the fuel cell system which concerns on embodiment. It is sectional drawing which shows the structure of the regulator which concerns on embodiment. It is a graph shown about the flow characteristic of the regulator in the fuel cell system concerning an embodiment. It is a graph shown about the flow characteristic of the regulator in the conventional fuel cell system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel cell system, 2 Fuel cell, 3 Oxygen gas supply system, 4 Hydrogen gas supply system, 13 Pressure adjustment system, 16 Compressor, 17 Humidifier, 25 Pressure introduction flow path, 32 Supply flow path, 40 Regulator, 57 Pressure regulation Room

Claims (7)

The inner space of the housing is partitioned by a diaphragm to which the valve body is connected, one of the spaces is configured to allow the fuel gas supplied to the fuel cell to flow from the primary side to the secondary side, and the other space is the reference pressure. Comprising a regulator configured as a pressure regulating chamber into which more pressurized gas is introduced;
The regulator includes a valve body corresponding to a secondary pressure of the fuel gas acting on the diaphragm and a pressure of the pressurized gas, and a biasing force of a biasing member that biases the valve body in a valve closing direction. Is adjusted so that the secondary pressure of the fuel gas supplied to the fuel cell can be adjusted,
The regulator has a valve opening characteristic of the valve body such that there is a region in which the valve body is closed and the flow rate becomes zero in a fuel gas supply flow rate region when the pressure regulating chamber is in a reference pressure state. The fuel cell system that is set.   2. The fuel cell system according to claim 1, wherein the point at which the flow rate becomes zero exists in a flow rate region that is at least half of the maximum supply flow rate in the supply flow rate region. The inner space of the housing is partitioned by a diaphragm to which the valve body is connected, one of the spaces is configured to allow the fuel gas supplied to the fuel cell to flow from the primary side to the secondary side, and the other space is the reference pressure. Comprising a regulator configured as a pressure regulating chamber into which more pressurized gas is introduced;
The regulator includes a valve body corresponding to a secondary pressure of the fuel gas acting on the diaphragm and a pressure of the pressurized gas, and a biasing force of a biasing member that biases the valve body in a valve closing direction. Is adjusted so that the secondary pressure of the fuel gas supplied to the fuel cell can be adjusted,
The regulator is a fuel cell system in which the valve opening characteristic of the valve body is set so that the secondary pressure of the fuel gas increases as the flow rate of the fuel gas increases.   The fuel cell system according to any one of claims 1 to 3, wherein the setting element that sets the valve opening characteristic of the valve body includes a property of the urging member.   The fuel cell system according to any one of claims 1 to 4, wherein the setting element that sets the valve opening characteristic of the valve body includes a property of the diaphragm.   The fuel cell according to any one of claims 1 to 5, wherein a pressure regulating valve that regulates a pressure of a pressurized gas introduced into the pressure regulating chamber is provided upstream of the pressure regulating chamber. system. The fuel cell according to any one of claims 1 to 6, wherein an accumulator for temporarily storing a pressurized gas introduced into the pressure regulating chamber is provided upstream of the pressure regulating chamber. system.

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