JP4063061B2 - Fuel evaporator and fuel cell vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel evaporator that vaporizes raw fuel to generate raw fuel gas, and more particularly to a heat input control technique at the time of startup.
[0002]
[Prior art]
As a means for generating a hydrogen-rich fuel gas to be supplied to a fuel cell, a technique for reforming a raw fuel gas obtained by vaporizing raw fuel (reformed raw material) such as methanol is known. In a catalytic combustion type fuel evaporator, a mixed gas of fuel and combustion air is combusted by catalytic action, and heat exchange is performed between the combustion gas and raw fuel. In such a fuel evaporator, since it is difficult to precisely control the temperature distribution of the combustion gas, overheating partially occurs or heat exchange becomes insufficient. In order to solve such problems, Japanese Patent Application Laid-Open No. 2001-272031 (Patent Document 1) detects the liquid level position of the heated fluid that is vaporized by exchanging heat with the heated fluid. A technique for performing heat exchange control between a heated fluid and a heated fluid based on the liquid level position is disclosed.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-272031
[0004]
[Problems to be solved by the invention]
However, the above prior art is directed to the heat input control during the operation of the fuel evaporator, and the initial heat amount at the time of starting the fuel evaporator is not considered. Without considering the residual amount of raw fuel, if a constant fuel amount and combustion air flow rate are always input at the start of the fuel evaporator, if the residual amount of raw fuel is large, the amount of heat will be insufficient, and it will be necessary to vaporize the raw fuel amount If the balance between the amount of heat and the amount of input heat is not balanced, the liquid level of the raw fuel rises and the temperature of the combustion gas suddenly decreases, which may cause a misfire. On the other hand, when the residual amount of the raw fuel is small, the amount of heat becomes excessive, the liquid level of the raw fuel is lowered, the combustion gas temperature is increased, and the fuel evaporator may be burned by overheating. Furthermore, if the initial heat amount is input without considering the raw fuel residual amount, even if the fuel amount and the combustion air flow rate are controlled by feeding back information such as the raw fuel gas vapor temperature, gas flow rate, and combustion gas combustion temperature, At startup, the temperature rise is delayed by the heat capacity of the raw fuel and the fuel evaporator, which are in a low temperature state, and it takes a long time to settle down to a steady state, making it difficult to obtain stable response characteristics.
[0005]
Accordingly, it is an object of the present invention to improve response characteristics at the time of starting the fuel evaporator, to improve startability and to stabilize temperature.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the heat exchange device of the present invention performs heat exchange between a heated fluid channel constituting a heated fluid channel and a heated fluid in the heated fluid channel. Heating means for vaporizing the fluid to be heated; Heat exchanger Depending on the residual amount of the heated fluid in the heated fluid flow path when stopped Heat exchanger And a control unit for determining an initial control amount of the heating means at the time of restart.
[0007]
Heat exchanger Depending on the residual amount of the heated fluid in the heated fluid flow path when stopped Heat exchanger By determining the initial control amount of the heating means at the time of restarting, it is possible to give a heat amount to the heated fluid without excess or deficiency, thereby improving the startability and stabilizing the temperature.
[0008]
The fuel evaporator according to the present invention includes a heated fluid flow path that constitutes a flow path of raw fuel, and heating means that vaporizes the raw fuel by exchanging heat between the raw fuel in the heated fluid flow path. A measuring means for measuring the residual amount of the raw fuel in the heated fluid flow path, a storage means for storing the residual amount of the raw fuel measured by the measuring means, and a controller for controlling the heat generation amount of the heating means. . The control unit Fuel evaporator While storing the residual amount of raw fuel measured by the measuring means at the time of stopping in the storage means, Fuel evaporator Reads the residual amount of raw fuel stored in the storage means at startup, calculates the initial heat amount for vaporizing the raw fuel remaining in the heated fluid flow path, and controls the heating means to initialize the raw fuel Supply heat.
[0009]
in this way, Fuel evaporator Remember the remaining amount of raw fuel at the time of stoppage, Fuel evaporator By supplying the initial amount of heat based on the residual amount of raw fuel stored in advance at the time of start-up, the fuel evaporator can be provided with a sufficient amount of heat, and startability can be improved and temperature can be stabilized.
[0010]
Preferably, the measuring means is a means for calculating an estimated value of the liquid level of the raw fuel from the temperature distribution of the raw fuel in the vertical direction of the heated fluid flow path. Since it is difficult to install a level gauge to measure the liquid level in the superheated fluid flow path, obtain an estimate of the raw fuel liquid level from the temperature distribution of the raw fuel in the vertical direction of the heated fluid flow path. By Fuel evaporator The configuration can be simplified.
[0011]
Preferably, the control unit includes a residual amount of raw fuel stored in the storage unit, Fuel evaporator The initial heat quantity is calculated from the initial temperature of the raw fuel at the time of starting. The remaining amount of raw fuel, Fuel evaporator By obtaining the initial heat amount for vaporizing the raw fuel from the initial temperature of the raw fuel at the time of startup, Fuel evaporator The amount of heat can be input to the fuel evaporator at startup without excess or deficiency.
[0012]
Preferably, the control unit controls the amount of heat supplied from the heating unit in accordance with the amount of heat required for vaporization of the raw fuel after controlling the input of the initial amount of heat. The amount of heat required in the normal operation sequence after the initial amount of heat is input is Fuel evaporator Because it depends on the state, Fuel evaporator It is necessary to adjust the calorific value of the heating means according to the state.
[0013]
A fuel cell vehicle according to the present invention includes a fuel evaporator according to the present invention, a reformer that reforms raw fuel vaporized by the fuel evaporator into a hydrogen-rich fuel gas, and fuel gas supply from the reformer. A fuel cell is provided for receiving and generating power necessary for driving the vehicle. With this configuration, it is possible to provide a fuel cell vehicle excellent in starting characteristics and stability.
[0014]
The computer program of the present invention is a computer system that controls a heat exchange device that performs heat exchange between a heated fluid in a heated fluid flow path and a heating means, and vaporizes the heated fluid. Heat exchanger While stopped Command to start heat exchanger Determining whether or not is input; Command to start heat exchanger Is entered, Heat exchanger Depending on the residual amount of the heated fluid in the heated fluid flow path when stopped Heat exchanger A step of determining an initial control amount of the heating unit at the time of restart and a step of controlling the heating unit according to the initial control amount and supplying the initial heat amount to the fluid to be heated are executed.
[0015]
By causing the computer system that controls the heat exchange device that vaporizes the fluid to be heated to execute the above processing steps, it is possible to give heat to the fluid to be heated without excess or deficiency, and to improve the startability and stabilize the temperature. be able to
The computer program of the present invention is a computer system for controlling a fuel evaporator that performs heat exchange between the raw fuel and the heating means in the heated fluid flow path and vaporizes the raw fuel. Fuel evaporator While driving Command to stop the fuel evaporator Determining whether or not is input; Command to stop the fuel evaporator Is input, the step of measuring the residual amount of raw fuel remaining in the heated fluid flow path and the step of storing the residual amount of raw fuel in the storage device are executed, Fuel evaporator While stopped Command to start the fuel evaporator Determining whether or not is input; Command to start the fuel evaporator Is input, the step of calculating the initial heat amount for vaporizing the remaining raw fuel based on the remaining amount of the raw fuel stored in the storage device, and the heating means to control the initial heat amount to the raw fuel And a step of inputting.
[0016]
By causing the computer system that controls the fuel evaporator that generates the raw fuel gas to execute the above processing steps, the fuel evaporator can be given a sufficient amount of heat, and the startability can be improved and the temperature stabilized. Can do.
[0017]
Preferably, the step of measuring the residual amount of the raw fuel is a step of calculating an estimated value of the liquid level of the raw fuel from the temperature distribution of the raw fuel in the vertical direction of the heated fluid passage. By obtaining an estimate of the liquid level of the raw fuel from the temperature distribution of the raw fuel in the vertical direction of the heated fluid flow path, Fuel evaporator The configuration can be simplified.
[0018]
Preferably, the step of calculating the initial heat quantity includes a residual amount of raw fuel stored in the storage device, and Fuel evaporator This is a step of calculating the initial heat quantity from the initial temperature of the raw fuel at the time of starting. The remaining amount of raw fuel, Fuel evaporator By obtaining the initial heat amount for vaporizing the raw fuel from the initial temperature of the raw fuel at the time of startup, Fuel evaporator The amount of heat can be input to the fuel evaporator at startup without excess or deficiency.
[0019]
As a computer-readable recording medium for recording the program of the present invention, for example, an optical recording medium (CD-RAM, CD-ROM, DVD-RAM, DVD-ROM, DVD-R, PD disk, MD disk, MO disk, etc.) Optically readable recording media), magnetic recording media (flexible disks, magnetic cards, magnetic tapes and other recording media capable of reading data), or memory elements (DRAM and other semiconductors) A portable recording medium such as a memory cartridge provided with a memory element and a ferroelectric memory element such as an FRAM is preferable.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, this embodiment will be described with reference to the drawings.
[0021]
FIG. 1 is a main block diagram of a vehicle (fuel cell vehicle) equipped with the fuel cell system of this embodiment. As shown in the figure, the fuel cell vehicle 10 mainly includes a fuel cell system 20 that functions as an on-board generator, a secondary battery 30 that functions as an auxiliary power source, and a power control unit 40 that performs power conversion control. And a motor 50 that drives the drive wheels 51 and 52 with electric power supplied from the fuel cell system 20 or the secondary battery 30 via the power control unit 40. The fuel cell vehicle 10 employs a front wheel drive system, and driven wheels 53 and 54 are disposed at the rear of the vehicle.
[0022]
The fuel cell system 20 generates a hydrogen-rich fuel gas by reforming a tank 21 that separately stores raw fuel and water such as methanol and natural gas, and a mixed solution of the raw fuel and water supplied from the tank 21. A reformer 22 that converts the chemical energy of the fuel gas supplied from the reformer 22 into electrical energy, and a controller 24 that controls the entire fuel cell system 20. Yes. The control unit 24 communicates with a system controller 43 to be described later, thereby performing the operation speed control of the air pump and the water pump disposed in the fuel cell system 20, the opening / closing control of the electromagnetic valve, and the like. Control the system to meet the required power. An air cleaner 84 and an air pump 83 are disposed in the air flow path of the fuel cell system 20, and the power generation air (oxidizing gas) filtered by the air cleaner 84 is pressurized by the air pump 83, and oxygen in the fuel cell 23. Supplied to the pole.
[0023]
The fuel cell 23 is a solid polymer electrolyte type fuel cell and has a stack structure in which a plurality of single cells are stacked. The polymer electrolyte fuel cell has the advantages of being able to start at room temperature, so the start-up time is short, high current density is obtained at room temperature, low-load operation is possible, and the size and weight can be reduced. It has excellent characteristics as a battery.
[0024]
The power control unit 40 includes a system controller 43 that detects the travel load from the accelerator opening, the vehicle speed, the shift position, the brake depression amount, etc. and calculates the amount of power supplied to the motor 50, and the fuel cell 23 or the secondary battery 30. A DC / DC converter 41 that transforms the supplied DC voltage to a charging voltage of the auxiliary battery 44 and an inverter 42 that converts the DC current into an AC current and supplies it to the motor 50 are configured. The inverter 42 includes a power switch element as a main circuit element, and converts a direct current into a three-phase alternating current. The amplitude and frequency of the three-phase alternating current are controlled by the system controller 43.
[0025]
The secondary battery 30 plays a role as a power source for starting the fuel cell system 20, a regenerative energy storage source at the time of brake regeneration, and an energy buffer at the time of load fluctuation accompanying acceleration or deceleration of the fuel cell vehicle 10. Cadmium storage batteries, nickel / hydrogen storage batteries, lithium secondary batteries and the like are suitable. A DC / DC converter 45 for transforming a direct current voltage is disposed in front of the secondary battery 30. The capacity of the secondary battery 30 can be appropriately set according to the traveling conditions, traveling performance (maximum speed, traveling distance, etc.) of the fuel cell vehicle 10, vehicle weight, and the like. As the motor 50, a three-phase synchronous motor is suitable.
[0026]
With the above-described configuration, the system controller 43 calculates the power to be supplied to the motor 50 based on the vehicle running load and the like, and the control unit 24 provides necessary instructions for obtaining a desired power generation amount in the fuel cell system 20. To give. The control unit 24 appropriately adjusts the flow rates of the fuel gas and the oxidizing gas to be supplied to the fuel cell 23 to obtain electric power necessary for traveling. The electric power generated by the fuel cell system 20 is supplied to the motor 50 and other auxiliary machines via the power control unit 40.
[0027]
FIG. 2 is an explanatory diagram of main blocks constituting the reformer. As shown in the figure, the reformer 22 includes a fuel evaporator 22a for vaporizing the raw fuel to generate the raw fuel gas, and a reforming unit for reforming the raw fuel gas into a hydrogen-rich fuel gas. 22b and a CO reduction unit 22c that removes carbon monoxide (CO) contained in the fuel gas. The fuel evaporator 22a is a heat exchange device that exchanges heat between the high-temperature combustion gas and the liquid raw fuel to vaporize the raw fuel. The fuel evaporator 22a is supplied with combustible fuel such as methanol and combustion air pressurized by the pumping force of the air pump 61 in order to generate combustion gas for vaporizing the raw fuel. The fuel is sprayed into the combustion air, burned by the action of the heated catalyst, and becomes combustion gas. The combustion exhaust gas is released to the outside. The detailed internal configuration of the fuel evaporator 22a will be described later.
[0028]
The raw fuel gas is supplied to the reforming unit 22b and reformed into a hydrogen-rich fuel gas by an autothermal method using both steam reforming and partial oxidation reforming. Inside the reforming part 22b, there are a copper-zinc catalyst (Cu-Zn catalyst), a copper-zinc-chromium catalyst (Cu-Zn-Cr catalyst), a copper-zinc-aluminum catalyst (Cu-Zn). -Al-based catalyst), zinc-chromium-based catalyst (Zn-Cr-based catalyst) and other reforming catalysts are filled, and the temperature range (200 to 600 ° C.) suitable for combined reforming is maintained. Oxygen required for partial oxidation reforming (reforming air) can be introduced into the reforming portion 22 b by opening the reforming air shut-off valve 81.
[0029]
The hydrogen-rich fuel gas generated in the reforming unit 22b is supplied to the CO reduction unit 22c. The CO reduction unit 22c is filled with a carrier carrying a platinum catalyst, a ruthenium catalyst, a palladium catalyst, a gold catalyst, or an alloy catalyst using these as a first element, which is a selective oxidation catalyst for carbon monoxide. Purifying air containing oxygen required for the selective oxidation reaction of carbon monoxide can be introduced into the CO reduction unit 22 c by opening the purifying air shut-off valve 82. In order to favorably promote the cell reaction in the fuel cell 23, the carbon monoxide concentration in the fuel gas is preferably about several ppm or less.
[0030]
FIG. 3 is a system configuration diagram centering on the fuel evaporator that constitutes the main part of the present embodiment. As shown in the figure, the fuel evaporator 22a mainly includes a heated fluid channel portion 60 through which a heated fluid such as combustion gas passes and a heated fluid channel portion through which a heated fluid such as raw fuel 90 passes. 70, and is configured to be able to exchange heat between them. At the fuel inlet located at the upstream end of the heating fluid channel 60, fuel such as methanol, gasoline, hydrogen off-gas, etc. is sprayed into the combustion air to generate a mixed gas, which is supplied to the heating fluid channel 60. An injector 62 for supply is provided. An air pump 61 for supplying combustion air is disposed upstream of the injector 62, and is configured to pressurize air introduced from the outside of the vehicle and introduce it into the injector 62. As the air pump 61, it is desirable that the air pump 61 is made of a light weight, durable, and heat resistant material having a capacity for maximum efficiency in the air supply amount required in the vicinity of the rated output of the fuel cell 23. .
[0031]
An electrocatalyst heater (EHC) 63 is disposed inside the pipe of the heating fluid passage section 60, and the mixed gas can be combusted by catalytic action in a heating environment. Further, a plurality of temperature sensors 91 to 96 are disposed in the heated fluid flow path section 70 so that the temperature of the raw fuel 90 can be measured. A pressure sensor 75 that measures the gas pressure of the combustion gas that passes through the flow path section and a pressure adjustment valve 76 that measures the gas flow rate are disposed downstream of the heating fluid flow path section 60. On the other hand, the raw fuel 90 is supplied to the upstream side of the heated fluid flow path portion 70 from the tank 21 via the pump 71.
[0032]
As raw fuel 90, methane (CH _Four ), Ethane (C ₂ H _Five ), Propane (C _Three H ₈ ), Butane (C _Four H _Ten ), Gasoline, light oil, natural gas, methanol (CH _Three OH), ethanol (C ₂ H _Five OH), DME (CH _Three OCH _Three ), Acetone (CH _Three C (= O) CH _Three ) Etc. can be used, but here, a case of using methanol is illustrated. A raw fuel 90 made of a mixed solution of methanol and water is supplied at a predetermined ratio. The water / methanol molar ratio is preferably in the range of 1.0 to 5.0, and more preferably in the range of 1.5 to 3.0. The supply amount of the raw fuel 90 is measured by a flow rate sensor 72 disposed in the vicinity of the entrance of the heated fluid flow path unit 70.
[0033]
The heated fluid flow path section 70 includes a plurality of pipe lines 70a to 70c that are erected in a substantially vertical direction so that the liquid level gradually increases every time the raw fuel 90 moves from downstream to upstream. The heating fluid channel section 60 is formed so as to meander downward in the vertical direction, and the combustion gas passing through the heating fluid channel section 60 is in a high temperature state with the raw fuel 90 having a high liquid level. Heat exchange is performed, and the raw fuel 90 is boiled and vaporized. In the process in which the combustion gas lowered in temperature by the heat exchange moves in the heating fluid flow path portion 60 in the downstream direction, further heat exchange is performed with the raw fuel 90 whose liquid level is gradually lowered to preheat the raw fuel. . A pressure sensor 75 that measures the gas pressure of the vaporized raw fuel gas and a pressure adjustment valve 76 that measures the flow rate of the raw fuel gas are disposed downstream of the heated fluid flow path section 70.
[0034]
The system controller 43 functions as a host controller of the control unit 24. When the system starts / stops, the system controller 43 sends a start / stop signal to the control unit 24. During system operation, the accelerator opening, vehicle speed, shift The power generation amount necessary for driving the fuel cell vehicle 10 is calculated from the position, the brake depression amount, the power generation state of the fuel cell 23, the charging state of the secondary battery 30, and the like, and an instruction regarding power generation control is sent to the control unit 24. The control unit 24 controls the air pump 61 and the injector 63 to adjust the input heat amount so that the power generation amount instructed by the system controller 43 is obtained, and also controls the pump 71 to adjust the raw fuel flow rate.
[0035]
The control unit 24 is configured as a computer system centered on a microcomputer, and reads various programs necessary for system control and various data stored in the ROM 25 and programs written in the ROM 25 and executes them appropriately. The CPU 26, the RAM 27 functioning as a work memory for the CPU 26, sensor output signals from the temperature sensors 91 to 96, the pressure sensors 73 and 75, and the flow rate sensors 72 and 74 described above are input, and the air pump 61 and the injector 62 described above are input. , An input / output port 28 that outputs a signal for controlling the drive of the pump 71, an EEPROM (nonvolatile memory) 29 as storage means for holding the liquid level H of the residual raw fuel 90 when the system is stopped, and the system stop Amount of time elapsed that measures the amount of time elapsed over a period It comprises a timer 31 serving as measuring means.
[0036]
Upon receiving the system stop signal from the system controller 43, the control unit 24 prepares for the next system activation, the raw fuel temperature detected by the temperature sensors 91 to 96, the pressure sensors 73 and 75, and the flow rate sensors 72 and 74, An estimated value of the liquid level H of the raw fuel 90 is calculated based on any or all of the sensor output signals of the fuel flow rate, the raw fuel gas pressure, the raw fuel temperature, the combustion gas pressure, and the combustion gas flow rate. Here, an example in which the estimated value of the liquid level H is calculated based on sensor output signals from the temperature sensors 91 to 96 will be described with reference to FIG.
[0037]
This graph is a graph showing the temperature distribution of the heated fluid channel 60, where the horizontal axis indicates the temperature of the raw fuel 90 and the vertical axis indicates the height from the bottom surface of the heated fluid channel part 70. T1 to T6 are detected temperatures of the temperature sensors 91 to 96, Te is the boiling point of the raw fuel 90, Ha is the height of the temperature sensors 91 and 94, Hb is the height of the temperature sensors 92 and 95, and Hc is the temperature sensor. The height of 93,96 is shown. An estimated value of the liquid level of the raw fuel 90 can be calculated from the temperature distribution of the raw fuel 90 in the vertical direction of the heated fluid flow path 70. If the estimated value of the liquid level H obtained from the sensor outputs of the temperature sensors 91 to 93 is H1, the nearest upper temperature of the boiling point of the raw fuel 90 is T2, and the nearest lower temperature is T3. ) Equation.
H1 = Hc + (Hb−Hc) (Te−T3) / (T2−T3) (1)
Further, if the estimated value of the liquid level H obtained from the sensor outputs of the temperature sensors 94 to 96 is H2, the temperature immediately above the boiling point of the raw fuel 90 is T4 and the temperature immediately below is T5, so H2 is (2) It can obtain | require from Formula.
H2 = Hb + (Ha-Hb) (Te-T5) / (T4-T5) (2)
H1 obtained in this way is the estimated liquid level of the pipeline 70a, and H2 is the estimated liquid level of the pipeline 70c. The estimated liquid level H3 of the central pipe line 70b can be estimated from the liquid level gradient of H1 and H2 by proportional distribution. After the estimated values H1 to H3 obtained in this way are written in the EEPROM 29, the system transits to a stop state. The estimated values H1 to H3 of the liquid level H written in the EEPROM 29 are held at least until the next start-up. In order to make the estimated values H1 to H3 of the liquid level H more accurate, it is desirable to correct errors in the estimated values H1 to H3 of the liquid level H using a Kalman filter.
[0038]
However, since the raw fuel temperature, raw fuel flow rate, raw fuel gas pressure, raw fuel temperature, combustion gas pressure, and combustion gas flow rate cannot be obtained correctly after a certain period of time has elapsed since the system stopped, these physical quantities are constant after the system is stopped. It is desirable to estimate the liquid level H based on what was acquired in time. In the above description, for convenience of explanation, the number of the temperature sensors 91 to 96 is six. However, the number of temperature sensors is not limited to this, and the estimated value of the liquid level H is more accurate by increasing the number of temperature sensors. It can be. In addition to the method of estimating the liquid level from the sensor output signal described above, the liquid level may be measured by a level sensor or the like.
[0039]
When the control unit 24 receives the system start signal from the system controller 43, the control unit 24 reads the estimated values H1 to H3 of the liquid level H written in the EEPROM 29 at the previous system stop, and the raw fuel 90 remaining in the heated fluid flow path unit 70. The mass M of is estimated. The mass M of the raw fuel 90 is obtained by obtaining the volume of the raw fuel 90 from the cross-sectional areas of the pipelines 70a to 70c and the estimated values H1 to H3 of the liquid level H and multiplying this by the specific gravity. Here, the specific heat of the raw fuel (liquid phase) is Cpl, the specific heat of the raw fuel (gas phase) is Cp, the latent heat of vaporization is Hvap, the raw fuel mass is M, the initial temperature of the raw fuel is T0, and the boiling point of the raw fuel is If the target temperature of Tboil and steam is Teg, the initial heat quantity Q to be input to the fuel evaporator 22a when the system is started, that is, the heat quantity Q required to vaporize the raw fuel 90 of mass M to the steam temperature Teg is , (3).
Q = {Cpl × (Tboil−T0) + Hvap + Cp × (Teg−Tboil)} × M (3)
As apparent from the equation (3), in order to obtain the initial heat quantity Q, an initial temperature T0 is required in addition to the mass M. When the system stop period is long, the temperature of the raw fuel 90 is lowered to room temperature, but when the system stop time is short, the raw fuel 90 is in a state of remaining heat. Therefore, the CPU 26 refers to the measured value of the system stop time measured by the timer 31 and, when the system stop time is long, calculates the initial heat quantity Q with the initial temperature T0 as the normal temperature. On the other hand, when the system stop time is short, the initial temperature T0 predicted from the elapsed time is obtained. Of course, the sensor output signals from the temperature sensors 91 to 96 may be taken in when the system is started, and the initial temperature T0 of the raw fuel 90 may be obtained.
[0040]
The controller 24 obtains the fuel flow rate Fb from the molar calorific value H of the fuel from Fb = Q / H. By multiplying the fuel flow rate Fb by the air-fuel ratio, the combustion air flow rate required to input the initial heat quantity Q to the fuel evaporator 22a can be obtained. The control unit 24 controls the air pump 61 and the injector 62 to control the amount of discharged fuel and the combustion air flow rate supplied to the heated fluid flow path unit 60, and inputs the initial heat quantity Q to the fuel evaporator 22a. . After the initial amount of heat Q is input, the amount of heat to be input to the fuel evaporator 22a is calculated according to the vehicle running load and the like. During system operation, it is desirable to adjust the fuel amount and the combustion air temperature by feeding back the steam temperature and flow rate of the raw fuel gas, the combustion gas temperature, and the like. For example, when the inlet temperature of the heating fluid channel section 60 is high, the air-fuel ratio is increased.
[0041]
FIG. 4 is a flowchart describing the heat input control process when the system is started. This routine is called when the system is started, and is repeatedly executed by the control unit 24 during the system operation period. First, the control unit 24 checks whether or not it is immediately after receiving an input of a system activation signal from the system controller 43, that is, whether or not it is immediately after activation of the system (step S1). If it is immediately after the system is started (step S1; YES), the control unit 24 reads the estimated value of the raw fuel liquid level H at the time of the previous system stop from the EEPROM 29 (step S2), and vaporizes the residual raw fuel. For this purpose, an initial heat quantity Q is calculated (step S3). Then, the air pump 61 is driven to supply combustion air, the amount of fuel discharged from the injector 62 is adjusted, and the initial heat quantity Q is input to the evaporation section 22a (step S4).
[0042]
On the other hand, if it is not immediately after system startup (step S1; NO), the control unit 24 shifts to a normal operation sequence (step S5). In this step, the control unit 24 controls the raw fuel temperature, the raw fuel flow rate, the raw fuel gas pressure, the raw fuel temperature, and the combustion gas pressure detected by the temperature sensors 91 to 96, the pressure sensors 73 and 75, and the flow rate sensors 72 and 74. Then, an estimated value of the liquid level H of the raw fuel is calculated on the basis of any or all of the sensor output signals of the combustion gas flow rate. When a system stop signal is input from the system controller 43 (step S6; YES), the estimated value of the liquid level H is written in the EEPROM 29 (step S7), and the system stops. Here, this routine ends. When the system stop signal is not input from the system controller 43 (step S6; NO), step S1, step S5, and step S6 are repeatedly executed.
[0043]
As described above, when the system is stopped, the estimated value of the liquid level H of the raw fuel is stored in the EEPROM 29, and when the system is started next time, the estimated value of the liquid level H is read from the EEPROM 29 to determine the residual amount of the raw fuel. By calculating and injecting the initial heat quantity Q required to vaporize this residual quantity, the initial quantity of heat can be given to the fuel evaporator 22a without excess or deficiency, and problems such as misfire or burning as described in the prior art. It is possible to solve the problem and to start quickly and stably.
[0044]
In the above description, the configuration in which the raw fuel is vaporized by exchanging heat between the combustion gas as the heating medium and the raw fuel as the medium to be heated has been exemplified. For example, the raw fuel may be vaporized by heating means such as an electric heater.
[0045]
Also, it is not always necessary to memorize the liquid level (or residual amount) of the raw fuel when the system is stopped, and to input the initial heat amount for vaporizing the liquid level (or residual amount) at the next system startup. The initial control amount of the heating means may be determined so as to input the amount of heat obtained by multiplying the amount of heat input immediately before the system is stopped by an appropriate correction coefficient. Here, the “initial control amount” means a control amount of the heating unit that is necessary for supplying the initial heat amount from the heating unit to the fluid to be heated at the time of starting the system. For example, when the heating unit is an electric heater, The amount of power supplied to the electric heater corresponds to this. Further, when the heating means is combustion gas, the rotational speed of an air pump that supplies combustion air, the drive amount of an injector that injects fuel, and the like correspond to this.
[0046]
【The invention's effect】
According to the present invention, the remaining amount of raw fuel is stored when the system is stopped, and the initial heat amount is input based on the remaining amount of raw fuel stored in advance at the next system startup. The amount of heat can be given to the battery without excess and deficiency, and the startability can be improved and the temperature can be stabilized.
[Brief description of the drawings]
FIG. 1 is a main block diagram of a vehicle equipped with a fuel cell system of an embodiment.
FIG. 2 is an explanatory diagram of main blocks constituting the reformer.
FIG. 3 is a system configuration diagram centering on a fuel evaporator according to the present embodiment;
FIG. 4 is a flowchart describing a heat input control process at system startup.
FIG. 5 is a graph showing a temperature distribution in a heated fluid channel.
[Explanation of symbols]
10. Fuel cell vehicle
20 ... Fuel cell system
21 ... Tank
22 ... reformer
22a ... Fuel evaporator
22b ... reforming section
22c ... CO reduction part
23 ... Fuel cell
24. Control unit
25 ... ROM
26 ... CPU
27 ... RAM
28 ... I / O port
29… EEPROM
30 ... Secondary battery
31 ... Timer
40 ... Power control unit
41 ... DC / DC converter
42 ... Inverter
43 ... System controller
50 ... Motor
60 ... Thermal fluid flow path
61 ... Air pump
62 ... Injector
63 ... Electric catalyst heater
70: Heated fluid flow path
71 ... Pump
72, 74 ... Flow sensor
73,75 ... Pressure sensor
81 ... Reformed air shut-off valve
82 ... Air shut-off valve for purification
90 ... Raw fuel

Claims (11)

A heat exchange device,
A heated fluid flow path constituting a heated fluid flow path;
Heating means for exchanging heat with the heated fluid in the heated fluid channel, and evaporating the heated fluid;
A control unit that determines an initial control amount of the heating unit when the heat exchange device is restarted according to a residual amount of the heated fluid in the heated fluid channel when the heat exchange device is stopped;
A heat exchange device comprising: A fuel evaporator,
A heated fluid flow path constituting a flow path of the raw fuel;
Heat means for exchanging heat with the raw fuel in the heated fluid flow path, and evaporating the raw fuel;
Measuring means for measuring the residual amount of raw fuel in the heated fluid flow path;
Storage means for storing the residual amount of the raw fuel measured by the measurement means;
A controller that controls the amount of heat generated by the heating means,
The control unit stores the residual amount of the raw fuel measured by the measurement unit when the fuel evaporator is stopped in the storage unit,
Reading the residual amount of the raw fuel stored in the storage means when starting the fuel evaporator, calculating the initial heat amount for vaporizing the raw fuel remaining in the heated fluid flow path, and heating the heating A fuel evaporator for controlling the means to supply an initial heat quantity to the raw fuel.   The fuel evaporator according to claim 2, wherein the measuring unit is a unit that calculates an estimated value of a liquid level of the raw fuel from a temperature distribution of the raw fuel in a vertical direction of the heated fluid flow path. The said control part calculates the said initial heat amount from the residual amount of the said raw fuel memorize | stored in the said memory | storage means, and the initial temperature of the said raw fuel at the time of starting of a fuel evaporator. Fuel evaporator.   5. The control unit according to claim 2, wherein the control unit controls the amount of heat supplied from the heating unit in accordance with a heat amount required for vaporization of the raw fuel after controlling the input of the initial heat amount. The fuel evaporator according to any one of the above.   A fuel evaporator according to any one of claims 2 to 5, a reformer for reforming raw fuel vaporized by the fuel evaporator into a hydrogen-rich fuel gas, and the reforming A fuel cell vehicle comprising a fuel cell that receives the supply of fuel gas from a vessel and generates power necessary for driving the vehicle. In a computer system for controlling a heat exchange device that performs heat exchange between a heated fluid in a heated fluid flow path and a heating means, and vaporizes the heated fluid,
Determining whether a command to start the heat exchange device is input while the heat exchange device is stopped;
When a command to start the heat exchange device is input,
Determining an initial control amount of the heating means when the heat exchange device is restarted according to a residual amount of the heated fluid in the heated fluid channel when the heat exchange device is stopped;
Controlling the heating means according to the initial control amount, and supplying an initial heat amount to the heated fluid;
A computer program that executes A computer system that controls a fuel evaporator that performs heat exchange between the raw fuel in the fluid flow path to be heated and the heating means, and vaporizes the raw fuel,
Determining whether a command is input to stop the fuel evaporator during operation of the fuel evaporator,
When a command to stop the fuel evaporator is input,
Measuring the residual amount of the raw fuel remaining in the heated fluid flow path;
Storing the residual amount of the raw fuel in a storage device,
Determining whether a command to start the fuel evaporator is input while the fuel evaporator is stopped;
When a command to start the fuel evaporator is input,
Calculating an initial heat amount for vaporizing the residual raw fuel based on the residual amount of the raw fuel stored in the storage device;
Controlling the heating means to input an initial heat amount to the raw fuel;
A computer program that executes   The step of measuring the residual amount of the raw fuel is a step of calculating an estimated value of the liquid level of the raw fuel from a temperature distribution of the raw fuel in a vertical direction of the heated fluid passage. Computer program. The step of calculating the initial heat amount is a step of calculating the initial heat amount from a residual amount of the raw fuel stored in the storage device and an initial temperature of the raw fuel at the time of starting the fuel evaporator. Item 10. The computer program according to item 8 or claim 9.   The computer-readable recording medium which recorded the computer program of any one of Claims 7 thru | or 10.

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