JP3783631B2 - Pure water purity maintenance system for mobile fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pure water purity maintaining system for a mobile fuel cell.
[0002]
[Prior art]
As a conventional fuel cell system for a moving body, there is one as disclosed in Japanese Patent Application Laid-Open No. 2000-208157. This is equipped with a pure water ion removal filter (purity improvement device) used for humidification and cooling and a conductivity detector, and the pure water is passed through the ion removal filter to maintain the pure water ion concentration appropriately, that is, purify. To maintain.
[0003]
[Problems to be solved by the invention]
However, in such a system, when the operation of the fuel cell is stopped, the specific resistance of pure water decreases (the ion concentration increases) during the stop, and it is difficult to restart the fuel cell. Were present.
[0004]
An object of the present invention is to solve the problem during the operation stop of such a fuel cell.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a mobile fuel cell comprising pure water purity improving means for use in a fuel cell, wherein purity reduction estimating means for estimating a decrease in purity of pure water from an operation stop time while the fuel cell is stopped. And purifying the purity of the pure water while the fuel cell is stopped based on the estimated value.
[0006]
According to a second invention, in the first invention, at least correction based on the outside air temperature is added to the estimation of the purity reduction of the pure water and the estimation of the degree of purity improvement during operation of the purity improving means.
[0007]
According to a third invention, in the first and second inventions, history correction based on integration of operation time of the purity improving means is added to the estimation of the degree of purity improvement during the operation of the purity improving means.
[0008]
According to a fourth invention, in the first to third inventions, there is provided switching means for switching the energy source of the purity improving means between a battery mounted on the moving body and an external power source outside the moving body, and the switching means detects an external power source. When the means detects energization of the external power source, the energy source of the purity improving means is switched from the battery to the external power source.
[0009]
According to a fifth invention, in the first to third inventions, when the energy source of the purity improving means is a battery mounted on a moving body, the battery has a battery remaining amount detecting means, and the remaining amount of the battery is a lower limit value. When this value is reached, the operation of the purity improving means is stopped.
[0010]
According to a sixth invention, in the first to third inventions, when the energy source of the purity improving means is a battery mounted on a moving body, the battery has a battery remaining amount detecting means, and the remaining amount of the battery is a lower limit value. When it reaches the value, it is judged that it is difficult to maintain the purity of the pure water, and the pure water is drained.
[0011]
According to a seventh aspect of the present invention, in the first to third aspects of the present invention, when it is determined that it is difficult to maintain the purity of pure water by estimating the deterioration of the purity improving means from the accumulated operation time of the purity improving means, Drain the water.
[0012]
In an eighth aspect based on the seventh aspect, at least correction based on the outside air temperature is added to the estimation of the deterioration.
[0013]
According to a ninth aspect of the invention, in the sixth to eighth aspects of the invention, there is provided reduction time prediction means for predicting a time of reduction from the purity at the time when it is difficult to maintain the purity of the pure water to a specified purity, Do not drain water.
[0014]
According to a tenth aspect, in the fifth to ninth aspects, when the fuel cell is restarted, it is difficult to maintain the purity of the pure water during the operation stop, and the operation of the purity improving means is stopped or the pure water is drained. Informing means for informing the driver of the fact is provided.
[0015]
【The invention's effect】
In the first aspect of the invention, it is possible to prevent the purity of pure water from being lowered during the stoppage of the fuel cell and making it difficult to restart the fuel cell.
[0016]
In the second invention, it is possible to accurately estimate the purity reduction and purity improvement of pure water.
[0017]
In the third invention, the degree of purity improvement by the purity improving means can be accurately estimated.
[0018]
In the fourth invention, by switching to the external power source, when the fuel cell is stopped, the purity improving means cannot be operated when the remaining amount of the battery is low, and the purity of pure water is lowered. It is possible to avoid that it becomes difficult to restart. In addition, switching between the battery and the external power source is easy.
[0019]
In the fifth invention, it is possible to prevent the battery from being discharged until the battery becomes unrecoverable.
[0020]
In the sixth aspect of the invention, when it is difficult to maintain the purity of pure water due to insufficient battery energy, the leakage of pure water can be prevented beforehand by draining the pure water.
[0021]
In the seventh invention, when the purity improving means is deteriorated and it is difficult to maintain the purity of the pure water, the leakage of the pure water can be prevented by discharging the pure water.
[0022]
In the eighth invention, it is possible to accurately estimate the deterioration of the purity improving means.
[0023]
In the ninth aspect of the invention, it is not necessary to immediately stop the operation of the fuel cell, and the operation of the fuel cell can be continued for a predetermined period.
[0024]
In the tenth invention, it is possible to reliably inform the driver of the reason why it is difficult to maintain the purity of pure water and the driver cannot operate.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
FIG. 1 is a configuration diagram showing the first embodiment, and shows an example in which a polymer electrolyte fuel cell 1 is used as a fuel cell for a moving body such as an automobile.
[0027]
Pure water is stored in the main tank 2, and the pure water in the main tank 2 is supplied for cooling the fuel cell 1 through the supply pipe 3 for cooling and the supply pump 4. After being led to the heat exchanger 5 and cooled, it is returned to the main tank 2.
[0028]
Although not shown, the pure water in the main tank 2 is also supplied for humidification of the solid polymer electrolyte membrane of the fuel cell 1 via a humidification supply pipe and a supply pump. When a hydrogen reformer or the like is provided, it is also supplied for the reforming reaction.
[0029]
The main tank 2 is connected to the inlet side and the outlet side of the sub-pipe 6, and a sub-pump 7 and an ion removal filter 8 as a pure water purity improving device are provided in the middle of the sub-pipe 6. When the sub pump 7 is driven, the pure water in the main tank 2 flows through the ion removal filter 8 to remove conductive ions in the pure water, and the purity of the pure water is maintained high.
[0030]
The driving of the sub pump 7 is controlled by the control device 10. A battery (vehicle-mounted battery) 11 mounted on a moving body (vehicle) is used as a driving power source for the subpump 7, and a circuit for taking in a household power source (external power source) is connected to the power source circuit 12 via a switching circuit 13. 14 is connected. The intake circuit 14 is provided with a power converter 15 that converts household power into a DC voltage for the battery 11. These power supplies are also used as control power supplies.
[0031]
Further, a signal from the outside air temperature sensor 16 that detects the outside air temperature is input to the control device 10. In addition, an operation signal and a stop signal for the fuel cell 1 are input to the control device 10.
[0032]
Based on these signals, the control device 10 controls the driving of the sub-pump 7 so that the purity of the pure water is properly maintained while the operation of the fuel cell 1 is stopped. Further, when the power converter 15 of the intake circuit 14 detects the voltage output, the control device 10 switches the switch 17 of the switching circuit 13 from the battery 11 side to the intake circuit 14 side, and detects the voltage 0. The switch 17 of the switching circuit 13 is returned to the battery 11 side.
[0033]
Next, the control content of the control device 10 when the operation of the fuel cell 1 is stopped will be described with reference to the flowcharts of FIGS.
[0034]
The operation starts when the operation of the fuel cell 1 is stopped by stopping the vehicle, that is, turning off the operation switch.
[0035]
In step 1, the stop time θ is set to zero.
[0036]
The loop of steps 2 to 7 is performed in a Δθ time period, and in step 2, Δθ time is counted as a unit time.
[0037]
In step 3, the outside air temperature T is read.
[0038]
In step 4, based on the outside air temperature T, the purity deterioration coefficient α is read from the purity deterioration map in which the purity deterioration coefficient (acceleration coefficient) α of pure water is set as shown in FIG.
[0039]
When the outside air temperature T is normal (normal temperature), the purity deterioration coefficient α is set to 1 with the degree of deterioration of the purity of pure water as a standard, and the higher the outside air temperature T, the faster the deterioration degree, so the purity deterioration coefficient α is increased. ing.
[0040]
In step 5, the Δθ time is corrected based on the purity deterioration coefficient α (Δθc = αΔθ).
[0041]
In step 6, the corrected Δθc time is added and the stop time θ is counted (θ _n = θ _n-1 + Δθc).
[0042]
In step 7, the stop time θ is compared with a sub pump stop time threshold value θstart as shown in FIG.
[0043]
When θ ≦ θstart, the loop of steps 2 to 7 is repeated.
[0044]
On the other hand, when θ> θstart, the process proceeds to step 8 and subsequent steps, and in step 8, the operation of the sub pump 7 is started.
[0045]
That is, the deterioration of the purity of pure water (increase in ion concentration) proceeds according to the stop time, and the degree thereof varies depending on the temperature. Therefore, the deterioration of the purity of pure water is estimated from the stop time, and this depends on the outside air temperature T. Correction is applied and the operation of the sub pump 7 is started based on the stop time after correction.
[0046]
In step 9, the operation time φ of the sub pump 7 is set to zero.
[0047]
The loop of Steps 10 to 16 is performed in a Δφ time period, and in Step 10, Δφ time is counted as a unit time.
[0048]
In step 11, the power source of the sub pump 7 is selected (described later).
[0049]
In step 12, the operating time Θ of the sub-pump 7 is accumulated (cumulative) (Θ _n = Θ _n-1 + Δφ).
[0050]
In step 13, the performance deterioration coefficient β is read from the performance deterioration map in which the performance deterioration coefficient (acceleration coefficient) β of the ion removal filter 8 is set as shown in FIG.
[0051]
Since the ion removal performance of the ion removal filter 8 gradually deteriorates while being used, the performance deterioration coefficient β is set to a small value according to the usage time.
[0052]
In step 14, the Δφ time is corrected based on the performance deterioration coefficient β (Δφc = βΔφ).
[0053]
In step 15, the corrected Δφc time is added to count the operation time φ (φ _n = φ _n-1 + Δφc).
[0054]
In step 16, the operation time φ is compared with a sub pump operation time threshold value φstop as shown in FIG.
[0055]
When φ ≦ φstop, the loop of steps 10 to 16 is repeated.
[0056]
On the other hand, when φ> φstop, the routine proceeds to step 17 where the operation of the sub pump 7 is stopped and the routine returns to step 1.
[0057]
That is, the performance of the ion removal filter 8 (the degree of improvement in the purity of pure water) is estimated from the cumulative operation time of the sub pump 7, and the operation time of the sub pump 7 is lengthened as the performance decreases.
[0058]
As shown in FIG. 8, when the power of the external pump is not supplied as shown in FIG. 8, the power of the battery 11 is supplied in step 32 with the switch 17 of the switching circuit 13 set to the battery 11 side. When there is power supply from the external power source, in step 33, the switch 17 of the switching circuit 13 is switched to the circuit 14 side for supply to supply power from the external power source.
[0059]
Since it comprised in this way, the fall of the purity of pure water (increase in ion concentration) can be prevented while the operation of the fuel cell 1 is stopped, and the restart of the fuel cell 1 after the stop can be prevented.
[0060]
In this case, a decrease in the purity of pure water is estimated from the stop time, and based on this, the subpump 7 that flows pure water through the ion removal filter 8 is operated, so that the purity of pure water can be maintained accurately.
[0061]
Moreover, since the correction | amendment by external temperature is added to estimation of the pure water purity fall, a purity fall can be estimated correctly and the purity of pure water can be maintained more correctly. Moreover, a detector such as the conductivity of pure water can be eliminated.
[0062]
On the other hand, the performance of the ion removal filter 8 (the degree of improvement in the purity of pure water) is estimated from the cumulative operation time of the sub-pump 7, and the operation time of the sub-pump 7 is lengthened as the performance decreases. It can be maintained properly.
[0063]
Further, by switching the power source of the sub pump 7 to an external power source, when the fuel cell 1 is stopped, when the remaining amount of the battery 11 is low, the sub pump 7 cannot be driven and the purity of pure water is reduced. It can be avoided that it is difficult to restart the fuel cell 1. In addition, switching between the battery 11 and an external power source is easy.
[0064]
Although the outside air temperature is used for correcting the estimation of the purity reduction of the pure water, the temperature of the pure water itself may be detected and the temperature of the pure water may be added to the correction. Until the operation of the fuel cell 1 is stopped and it converges to the outside air temperature, the purity deterioration degree of pure water is determined based on the temperature of pure water, that is, the purity deterioration coefficient α in FIG. 3 is selected.
[0065]
9 to 12 show a second embodiment. This is when the remaining amount (SOC) of the battery 11 reaches the lower limit without switching to an external power source, and when the purity of pure water becomes difficult to maintain due to deterioration of the ion removal filter 8. It is.
[0066]
As shown in FIG. 9, a battery remaining amount detector 20 that detects the remaining amount of the battery 11 is provided, and the signal is input to the control device 10. Moreover, the drain valve 21 which drains pure water is provided in the main tank 2, and the control apparatus 10 controls the opening and closing. Other configurations are the same as those in FIG.
[0067]
The flow in FIGS. 10 to 12 starts when the operation of the fuel cell 1 is stopped by stopping the vehicle, that is, by turning off the operation switch.
[0068]
In step 1, the stop time θ is set to zero.
[0069]
The loop of steps 2 to 7 is performed in a Δθ time period, and in step 2, Δθ time is counted as a unit time.
[0070]
In step 3, the outside air temperature T is read.
[0071]
In step 4, based on the outside air temperature T, the purity deterioration coefficient α is read from the purity deterioration map in which the purity deterioration coefficient (acceleration coefficient) α of pure water is set as shown in FIG.
[0072]
In step 5, the Δθ time is corrected based on the purity deterioration coefficient α (Δθc = αΔθ).
[0073]
In step 6, the corrected Δθc time is added and the stop time θ is counted (θ _n = θ _n-1 + Δθc).
[0074]
In step 7, the stop time θ is compared with the sub-pump stop time threshold value θstart as shown in FIG.
[0075]
When θ ≦ θstart, the loop of steps 2 to 7 is repeated.
[0076]
On the other hand, when θ> θstart, the process proceeds to step 8 and subsequent steps, and in step 8, the operation of the sub pump 7 is started.
[0077]
In step 9, the operation time φ of the sub pump 7 is set to zero.
[0078]
The loop of Steps 10 to 19 (except when jumping as described later) is performed in a Δφ time period. In Step 10, Δφ time is counted as a unit time.
[0079]
In step 11, the power source of the sub pump 7 is selected (previous FIG. 8).
[0080]
In step 12, the operation time Θ of the sub pump 7 is accumulated (accumulated).
[0081]
Although the deterioration of the ion removal filter 8 is estimated based on the accumulated operation time Θ, since the ion removal rate of the ion removal filter 8 changes depending on the temperature, the purity deterioration coefficient α (the previous FIG. 4) is read based on the outside air temperature T. Then, the accumulated operating time Θ is corrected (Θ _n = Θ _n−1 + Δφ · α).
[0082]
In step 13, the performance deterioration coefficient β is read from the performance deterioration map in which the performance deterioration coefficient (acceleration coefficient) β of the ion removal filter 8 is set as shown in FIG. .
[0083]
In step 14, the Δφ time is corrected based on the performance deterioration coefficient β (Δφc = βΔφ).
[0084]
In step 15, the corrected Δφc time is added to count the operation time φ (φ _n = φ _n-1 + Δφc).
[0085]
In steps 16 and 17, it is determined whether power is being supplied from the battery 11 or whether the remaining amount of the battery 11 is a lower limit value (for example, 30 to 50%).
[0086]
When the power is not being supplied from the battery 11 and when the remaining amount of the battery 11 is not the lower limit value even when the power is being supplied from the battery 11, the process proceeds to step 18 and the remaining amount of the battery 11 is being supplied with power from the battery 11. When is the lower limit value, the routine jumps to step 22.
[0087]
In step 18, it is determined whether the cumulative operation time Θ of the sub-pump 7 has exceeded the allowable value # ΘMAX.
[0088]
When the cumulative operation time Θ does not exceed the allowable value # ΘMAX, the process proceeds to step 19, and when it exceeds, the purity improving means (ion removal filter 8) deterioration flag is set at step 21 and the process jumps to step 22.
[0089]
In step 19, the operation time φ is compared with the sub-pump operation time threshold value φstop as shown in FIG.
[0090]
When φ ≦ φstop, the loop of steps 10 to 19 (except when jumping) is repeated. When φ> φstop, the process proceeds to step 20, the operation of the sub pump 7 is stopped, and the process returns to step 1.
[0091]
On the other hand, when jumping to Step 22, the operation of the sub pump 7 is stopped (interrupted), and the purity improving operation interruption flag is set, and the process proceeds to Step 23 and the subsequent steps.
[0092]
In step 23, the amount of the purity improvement due to the stop (interruption) of the sub pump 7 is set as the stop time θ (becomes the initial value after step 24).
[0093]
This is because the purity is improved by the amount of time the sub-pump 7 was operated during φ with respect to the time (sub-pump stop time threshold θstart) that was stopped before the sub-pump 7 was operated as shown in equation (1). Since the operation has been performed, the amount (operation time φ / sub-pump operation time threshold φstop) is converted into a stop time and subtracted.
[0094]
θ = θstart (φstop−φ) / φstop (1)
The loop of steps 24 to 29 is performed in the Δθ time period similarly to the loop of steps 2 to 7, and in step 24, Δθ time is counted as a unit time.
[0095]
In step 25, the outside air temperature T is read.
[0096]
In step 26, based on the outside temperature T, the purity deterioration coefficient α is read from the purity deterioration map in which the purity deterioration coefficient (acceleration coefficient) α of pure water is set as shown in FIG.
[0097]
In step 27, the Δθ time is corrected based on the purity deterioration coefficient α (Δθc = αΔθ).
[0098]
In step 28, the corrected Δθc time is added and the stop time θ is counted (θ _n = θ _n-1 + Δθc).
[0099]
In step 29, the stop time θ is compared with the sub-pump stop time threshold value θstart as shown in FIG.
[0100]
When θ ≦ θstart, the loop of steps 24 to 29 is repeated.
[0101]
When θ> θstart, the routine proceeds to step 30, where the drain valve 21 of the main tank 2 is opened to drain the pure water of the main tank 2, and a pure water drain flag is set.
[0102]
When the purity improving means deterioration flag, the purity improving operation interruption flag, and the pure water drain flag are set (= 1), the driver is notified accordingly. In this case, when the fuel cell 1 is started, the driver is notified by turning on a corresponding warning light or the like.
[0103]
According to this, it is possible to prevent the battery 11 from continuing discharging until it cannot be recovered.
[0104]
In addition, when the energy of the battery 11 is insufficient or the ion removal filter 8 is deteriorated and the purity of the pure water cannot be maintained, the leakage of the pure water can be prevented by draining the pure water from the fuel cell system. it can.
[0105]
Further, the performance and deterioration of the ion removal filter 8 can be accurately estimated from the accumulated operation time of the sub-pump 7, and the correction and the deterioration due to the outside temperature are added to these estimates, so that the performance and deterioration of the ion removal filter 8 can be estimated more accurately. .
[0106]
On the other hand, when it is determined that the purity of the pure water cannot be maintained, the time for the reduction from the purity at that time to the specified purity is predicted (steps 23 to 29), and during that time, the pure water is not drained. Therefore, the operation of the fuel cell 1 can be continued for a predetermined period.
[0107]
Although the outside air temperature is used for correction of purity reduction of pure water, performance of the ion removal filter 8 and estimation of deterioration, the temperature of pure water itself may be detected and the temperature of pure water may be added to the correction.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment;
FIG. 2 is a flowchart showing control contents.
FIG. 3 is a flowchart showing control contents.
FIG. 4 is a characteristic diagram of a purity deterioration map.
FIG. 5 is a setting characteristic diagram of a sub-pump stop time threshold value.
FIG. 6 is a characteristic diagram of a performance deterioration coefficient map.
FIG. 7 is a setting characteristic diagram of a sub pump operation time threshold value.
FIG. 8 is a flowchart showing control contents.
FIG. 9 is a configuration diagram showing a second embodiment;
FIG. 10 is a flowchart showing control contents.
FIG. 11 is a flowchart showing control contents.
FIG. 12 is a flowchart showing control contents.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Main tank 3 Supply piping 4 Supply pump 5 Heat exchanger 6 Sub piping 7 Sub pump 8 Ion removal filter 10 Control apparatus 11 Battery 13 Switching circuit 16 Outside temperature sensor 20 Battery residual quantity detector 21 Drain valve

Claims (10)

In a fuel cell for a mobile body provided with a means for improving purity of pure water used in a fuel cell,
Purity reduction estimation means for estimating a decrease in purity of pure water from the shutdown time during the shutdown of the fuel cell,
A pure water purity maintaining system for a mobile fuel cell, characterized in that, based on the estimated value, the pure water purity improving means is operated while the fuel cell is stopped. The purity of the pure water of the mobile fuel cell according to claim 1, wherein at least a correction based on an outside air temperature is added to the estimation of the purity reduction of the pure water and the estimation of the degree of purity improvement during operation of the purity improving means. Maintenance system. 3. The purity of pure water of a mobile fuel cell according to claim 1 or 2, wherein a history correction based on an accumulation of operation time of the purity improving means is added to the estimation of the degree of purity improvement during operation of the purity improving means. Maintenance system. A switching means for switching the energy source of the purity improving means between a battery mounted on the moving body and an external power source outside the moving body;
The moving unit according to any one of claims 1 to 3, wherein the switching unit switches the energy source of the purity improving unit from a battery to an external power source when the external power source detecting unit detects energization of the external power source. Pure water purity maintenance system for industrial fuel cells. In the case where the energy source of the purity improving means is a battery mounted on a mobile body, the battery is provided with a battery remaining amount detecting means, and when the remaining amount of the battery reaches a lower limit value, the operation of the purity improving means is stopped. The pure water purity maintenance system of the fuel cell for mobile bodies as described in any one of Claims 1-3 characterized by these. In the case where the energy source of the purity improving means is a battery mounted on a moving body, the battery is provided with means for detecting the remaining amount of the battery, and when the remaining amount of the battery reaches the lower limit value, it is determined that it is difficult to maintain the purity of pure water. Then, the pure water purity maintaining system for a mobile fuel cell according to any one of claims 1 to 3, wherein pure water is drained. The pure water is drained when it is judged that the purity of the purity improving means is deteriorated from the accumulated operation time of the purity improving means and it is determined that the purity of the pure water is difficult to maintain. The pure water purity maintenance system of the fuel cell for mobile bodies as described in any one. 8. The pure water purity maintenance system for a mobile fuel cell according to claim 7, wherein at least correction based on outside air temperature is added to the estimation of the deterioration. 9. The apparatus according to claim 6, further comprising a decrease time predicting unit that predicts a time during which the purity of the pure water is determined to be difficult to maintain from the purity at the time when it is difficult to maintain the purity of the pure water. The pure water purity maintenance system of the fuel cell for moving bodies as described in any one. At the time of restart of the fuel cell, it is characterized in that it is provided with a notification means for notifying the driver that the purity of the purity improving means is stopped or the pure water is drained because it is difficult to maintain the purity of the pure water during the operation stop. The pure water purity maintenance system of the fuel cell for mobile bodies as described in any one of Claims 5-9.

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