JP2006025517A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system which avoids excess pressurization of water in a fuel cell body generated by the acceleration of a vehicle. <P>SOLUTION: The fuel cell system includes the fuel cell body 1 for generating power, according to electrochemical reaction of a hydrogen with an oxygen in supply gas, a cooling-water circulating path 4 for circulating cooling water used, when the fuel cell body 1 generates the power, a water-pressure regulator (cooling water pump 5 or a pressure regulating valve 6) for regulating the pressure of the cooling water in the cooling-water circulating path 4, an acceleration estimator (8, 9) for estimating the acceleration of the vehicle 11 mounted with the fuel cell body 1 and the cooling water circulating path 4, and a controller 2 for controlling the operation of the water pressure regulator (5, 6) according to the acceleration of the vehicle 11 to be estimated by the acceleration estimator (8, 9). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system having means for controlling the pressure of water in a fuel cell body.

  The fuel cell body that generates electricity by the electrochemical reaction between hydrogen in the fuel gas and oxygen in the oxidant gas must be cooled sufficiently to remove the heat generated by the power generation, and the temperature distribution within the fuel cell body In order to eliminate this unevenness, it is desirable to flow as much cooling water as possible. If the temperature of the fuel cell body is uneven, the electrochemical reaction becomes non-uniform, resulting in a decrease in power generation efficiency, deterioration of the fuel cell body, and the like.

  Further, in order to manage the electrolyte membrane in the fuel cell main body in a saturated water-containing state, the fuel gas supplied to the fuel cell main body needs to be moistened, and pure water (humidified water) is used for humidifying the fuel gas etc. ).

2. Description of the Related Art Conventionally, a fuel cell system that circulates cooling water in a cooling water circulation path to cool a fuel cell main body is known (see, for example, Patent Document 1). A water leakage abnormality in the cooling water circuit is detected from the difference between the pressure and the cooling water pressure at the outlet.
JP 2003-168454 A

  However, when a fuel cell system having a cooling water circulation path is mounted on a vehicle, it may not be sufficient to manage the pressure difference between the inlet and outlet of the fuel cell body. That is, acceleration other than gravity occurs when driving on a curve, sudden acceleration / deceleration, or rough road. Due to the acceleration and the inertia of the cooling water or the humidifying water, as shown in FIG. 7, a portion where the cooling water pressure or the humidifying water pressure is partially increased is generated inside the fuel cell main body. Since the pressure resistance of the cooling water and the humidifying water in the fuel cell main body is limited, there is a risk of causing the leakage of the cooling water or the humidifying water or the destruction of the fuel cell main body.

  A feature of the present invention is that a fuel cell body that generates electric power by an electrochemical reaction between hydrogen in fuel gas and oxygen in oxidant gas, and water (for example, cooling water or humidification) used when the fuel cell body generates power. Acceleration estimation for estimating the acceleration of a vehicle equipped with a water circulation path through which water) circulates, a water pressure adjustment unit (for example, a pump or a pressure adjustment valve) that adjusts the pressure of water in the water circulation path, and the fuel cell body and the water circulation path The gist of the present invention is a fuel cell system including a control unit (for example, an acceleration sensor or a vehicle speed sensor) and a control unit that controls the operation of the water pressure adjustment unit according to the acceleration of the vehicle estimated by the acceleration estimation unit.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which avoids the over pressurization of the water in the fuel cell main body produced by the acceleration of a vehicle can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  As shown in FIG. 1, the fuel cell system according to the embodiment of the present invention includes a fuel cell main body 1 that generates electric power by an electrochemical reaction between hydrogen and oxygen in a supply gas, and when the fuel cell main body 1 generates electric power. A cooling water circulation path 4 as an example of a water circulation path through which water to be used is circulated, a cooling water pump 5 and a pressure adjustment valve 6 as an example of a water pressure adjusting unit for adjusting the pressure of the cooling water in the cooling water circulation path 4, and fuel An acceleration sensor 8 and an acceleration calculation unit 9 (hereinafter referred to as “vehicle speed sensor”) as an example of an acceleration estimation unit that estimates the acceleration of the vehicle 11 on which the battery body 1 and the cooling water circulation path 4 are mounted, and the acceleration sensor 8 or the vehicle A controller 2 as an example of a control unit that controls the cooling water pump 5 or the pressure regulating valve 6 according to the acceleration of the vehicle 11 estimated by the speed sensor 9, and an example of a pressure estimation unit that estimates the pressure of the cooling water; All pressure sensors 7, a pressure limit value database 10 that stores the pressure limit value of coolant that is estimated to operate normally, and a radiator 3 that cools the coolant in the coolant circulation path 4. And have.

  In the embodiment of the present invention, as “water” used when the fuel cell main body 1 generates electric power, cooling water for cooling the heat generated when the fuel cell main body 1 generates electric power will be described as an example.

  Cooling water circulates in the cooling water circulation path 4. A cooling water pump 5, a pressure sensor 7, a fuel cell main body 1, a pressure adjustment valve 6, and a radiator 3 are arranged on the cooling water circulation path 4. The cooling water pumped by the cooling water pump 5 absorbs heat generated by the power generation in the fuel cell main body 1, the circulation amount is controlled by the pressure regulating valve 6, the cooling water is cooled in the radiator 3, and the cooling water pump 5 again. Come back to. As the cooling water circulates in the cooling water circulation path 4, the heat generated in the fuel cell main body 1 is discharged to the outside of the system. The pressure sensor 7 detects the pressure of the cooling water at the inlet of the fuel cell main body 1.

  The cooling water pump 5 adjusts the circulation amount of the cooling water in the cooling water circulation path 4 by controlling the rotation speed. Thereby, the cooling water pump 5 can function as a “water pressure adjusting unit”. The pressure regulating valve 6 adjusts the circulation amount of the cooling water in the cooling water circulation path 4 by controlling the opening degree. Thereby, the pressure regulating valve 6 can function as a “water pressure regulating unit”.

  The acceleration sensor 8 functions as an “acceleration estimation unit” by directly detecting the acceleration in the front-rear, left-right, and vertical directions of the vehicle 11. Further, the vehicle speed sensor 9 functions as an “acceleration estimation unit” by continuously detecting the speed of the vehicle 11 and differentiating the speed of the vehicle 11 to calculate the acceleration in the front-rear direction of the vehicle 11. The acceleration sensor 8 includes one or more sensors that detect acceleration in the front-rear, left-right, and vertical directions of the vehicle 11. Specifically, one acceleration sensor 8 may be configured by combining a front-rear sensor, a left-right sensor, and an up-down sensor, and the front-rear, left-right, and vertical accelerations may be combined into one acceleration sensor 8. You may detect by. Japanese Patent Laid-Open No. 11-218544 has a detailed description of an acceleration sensor having a function of detecting acceleration in the front-rear, left-right, and vertical directions. The acceleration sensor 8 detects acceleration other than gravitational acceleration applied to the vehicle 11. That is, even when the vehicle 11 is traveling on an uphill, uphill, right slope, or left slope road, the gravitational acceleration applied to the vehicle 11 and other accelerations are the same as when the vehicle 11 is traveling on a flat road. It is desirable to detect them separately.

  The controller 2 acquires information on the pressure of the cooling water from the pressure sensor 7, and acquires information on acceleration in the front-rear, left-right, and vertical directions of the vehicle 11 from the acceleration sensor 8 or the vehicle speed sensor 9. When the cooling water pressure exceeds the pressure limit value in the pressure limit value database 10 and the acceleration of the vehicle 11 is not substantially zero, the controller 2 uses the cooling water pump 5 based on the acceleration information. And the opening degree of the pressure regulating valve 6 is controlled. Thereby, the pressure of the cooling water in the cooling water circulation path 4 can be controlled. When the cooling water pressure exceeds the pressure limit value in the pressure limit value database 10 and the acceleration of the vehicle 11 is substantially zero, the controller 2 indicates that an abnormality has occurred in the fuel cell system. Judging, the power generation of the fuel cell body 1, that is, the fuel cell system is stopped. When the pressure of the cooling water does not exceed the pressure limit value in the pressure limit value database 10, the controller 2 does not control the pressure of the cooling water. The controller 2 may control both the rotational speed of the cooling water pump 5 and the opening degree of the pressure regulating valve 6 at the same time when controlling the pressure of the cooling water in the cooling water circulation path 4, or only one of them. You may control.

  As shown in FIG. 2, the pressure limit value database 10 stores a graph showing the relationship between the control target pressure that the controller 2 refers to when controlling the pressure of the cooling water and the output of the fuel cell main body 1. . The control target pressure has a normal value and an abnormal value, and the normal value and the abnormal value monotonously increase with an increase in the output of the fuel cell body 1. The controller 2 controls the rotation speed of the cooling water pump 5 or the opening of the pressure adjustment valve 6 so that the pressure of the cooling water becomes a normal value of the control target pressure according to the output of the fuel cell main body 1. When the cooling water pressure becomes equal to or higher than the abnormal value of the control target pressure, the controller 2 controls the number of revolutions of the cooling water pump 5 or the opening of the pressure regulating valve 6 to lower the cooling water pressure.

  With reference to FIG. 3, the operation | movement procedure of the controller 2 of FIG. 1 is demonstrated.

  (A) First, in the S1 stage, the fuel cell system is operating normally. On the premise of this state, in step S2, the controller 2 determines whether or not the pressure of the cooling water is increasing. Specifically, the controller 2 determines whether the pressure of the cooling water is equal to or higher than the abnormal value of the control target value in FIG. 2 based on the information on the pressure of the cooling water acquired from the pressure sensor 7. When the pressure of the cooling water is not less than the abnormal value of the control target value in FIG. When the pressure of the cooling water is lower than the abnormal value of the control target value in FIG. 2 (NO in step S2), the process proceeds to step S1. Therefore, in the step S2, the controller 2 monitors that the pressure of the cooling water rises above the abnormal value of the control target value in FIG.

  (B) In step S3, the controller 2 determines whether or not the vehicle 11 is accelerating. Specifically, based on the information on the acceleration in the front / rear, left / right and up / down directions of the vehicle 11 acquired from the acceleration sensor 8 or the vehicle speed sensor 9, whether the acceleration in the front / rear, left / right and up / down directions is substantially zero or not. Determine whether. When the acceleration is substantially zero (NO in step S3), the process proceeds to step S5, where the controller 2 determines that an abnormality has occurred in the fuel cell system and stops the fuel cell system. That is, the power generation of the fuel cell main body 1 is stopped. On the other hand, if the acceleration is not substantially zero (YES in step S3), the process proceeds to step S4, where the controller 2 determines the cooling water pump according to the acceleration of the vehicle so that the cooling water pressure becomes a normal value of the control target pressure. The pressure of the cooling water is adjusted by controlling the rotational speed of 5 or the opening of the pressure regulating valve 6. Thereafter, the process returns to S2. Thereafter, steps S1 to S4 are repeated unless the fuel cell system is stopped in step S5.

  As shown in FIGS. 4 (a) and 4 (b), when the controller 2 does not control the cooling water pressure in the S4 stage (during non-control), the acceleration of the vehicle 11 is increased in the longitudinal, lateral, and vertical directions. Accordingly, the pressure of the cooling water also increases. On the other hand, when the controller 2 controls the cooling water pressure based on the acceleration information in step S4 (during control), the cooling water pressure can be kept substantially constant even when the vehicle acceleration changes. it can.

  When the controller 2 adjusts the pressure of the cooling water by controlling the number of rotations of the cooling water pump 5, as shown in FIGS. 5 (a) and 5 (b), the front / rear, left / right and up / down directions of the vehicle 11 are used. The rotational speed of the cooling water pump 5 is temporarily lowered in accordance with the increase in acceleration. Thereby, the rise in the pressure of the cooling water is suppressed, and the pressure of the cooling water can be kept substantially constant as shown in FIG.

  When the controller 2 adjusts the pressure of the cooling water by controlling the opening of the pressure regulating valve 6, as shown in FIGS. 6 (a) and 6 (b), the front and rear, the left and right, and the vertical direction of the vehicle 11 As the acceleration increases, the opening of the pressure regulating valve 6 is temporarily increased. Thereby, the rise in the pressure of the cooling water is suppressed, and the pressure of the cooling water can be kept substantially constant as shown in FIG.

  As described above, in the vehicle 11 (fuel cell vehicle) equipped with the fuel cell system having the cooling water system (3 to 7) for cooling the heat generated by the power generation of the fuel cell main body 1, the acceleration sensor 8 or the vehicle The acceleration is estimated using the speed sensor 9, and the pressure of the cooling water is controlled according to the estimated acceleration. As a result, as shown in FIG. 7, it is possible to suppress a temporary and partial increase in the pressure of the cooling water in the fuel cell main body 1 due to the acceleration that occurs when the vehicle 11 suddenly accelerates / decelerates, turns sharply, or travels on a rough road. . Therefore, it is possible to avoid leakage of cooling water and destruction of the fuel cell main body 1. In addition, since cooling water can flow to the maximum when no acceleration is generated, temperature unevenness in the fuel cell main body 1 can be reduced, and power generation performance can be improved and fuel cell deterioration can be reduced.

  In addition, by having an acceleration sensor 8 that directly measures acceleration in the front / rear / left / right / up / down direction, the vehicle (fuel cell vehicle) 11 can quickly respond to all situations such as sudden acceleration / deceleration, sudden turning, and rough road traveling. Can respond.

  Further, by providing a vehicle speed sensor 9 that estimates the acceleration of the vehicle front-rear method from the differential of the speed of the vehicle 11, the front-rear direction of the acceleration sensor 8 that can detect the front-rear direction or the acceleration sensor 8 that can detect the acceleration in three directions is provided. The detection function can be omitted.

  When the acceleration of the vehicle 11 is zero and the pressure of the cooling water is increasing, it is determined that an abnormality has occurred in the fuel cell system, and the fuel cell system is stopped. Thereby, it is possible to distinguish between a pressure increase caused by the acceleration of the vehicle 11 and an abnormal pressure rise caused by a failure of the cooling water pump 5 or clogging in the cooling water circulation path 4.

(Other embodiments)
As described above, the present invention has been described according to one embodiment. However, it should not be understood that the description and the drawings, which form a part of this disclosure, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment of the present invention, the “water” used when the fuel cell main body 1 generates power has been described by taking cooling water for cooling the heat generated when the fuel cell main body 1 generates power as an example. However, the present invention is not limited to this. For example, the “water” used when the fuel cell main body 1 generates power may be humidified water for humidifying the supply gas supplied to the fuel cell main body 1. In this case, the “water circulation path” through which water used when the fuel cell body 1 generates electricity is a humidified water circulation path through which the humidified water circulates, and the “water pressure adjusting unit” that adjusts the pressure of water in the water circulation path is The pressure adjusting valve that adjusts the pressure of the humidifying water pump and the humidifying water, and the controller 2 controls the rotation speed of the humidifying water pump and the opening of the pressure adjusting valve that adjusts the pressure of the humidifying water according to the acceleration of the vehicle 11. To do. The pressure limit value database 10 stores the pressure limit value of the humidified water that can operate normally.

  When the fuel cell system includes both the cooling water system shown in FIG. 1 and the humidification water system, the pressure control may be performed on at least one of the water. Of course, pressure control may be simultaneously performed on both the cooling water system and the humidifying water system.

  As described above, even if the “cooling water” in the embodiment of the present invention is replaced with “humidified water”, the same purpose can be achieved and the same effect can be obtained. That is, it is possible to suppress a temporary and partial increase in the pressure of the humidified water in the fuel cell main body 1 due to acceleration that occurs when the vehicle 11 suddenly accelerates / decelerates, turns sharply, or travels on a rough road. Therefore, leakage of humidified water and destruction of the fuel cell main body 1 can be avoided. In addition, when acceleration is not generated, a necessary amount of humidified water can be flowed, so that insufficient humidification of the electrolyte membrane in the fuel cell main body 1 can be avoided, and power generation performance is improved and fuel cells are deteriorated. Reduction can be realized.

  Further, when the acceleration of the vehicle 11 is zero and the pressure of the humidified water is increasing, it is determined that an abnormality has occurred in the fuel cell system, and the fuel cell system is stopped. Thereby, it is possible to distinguish between a pressure increase caused by the acceleration of the vehicle 11 and an abnormal pressure rise caused by a failure of the humidifying water system pump or clogging in the humidifying water circulation path.

  Note that the pressure of the cooling water and the pressure of the humidifying water described above are desirably differential pressures from the supply gas including the fuel gas or the oxidant gas supplied to the fuel cell main body 1. Abnormal water leakage in the fuel cell main body 1 can be prevented more accurately. Of course, the absolute pressure of water in the water circuit may be used.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters according to the scope of claims reasonable from this disclosure.

1 is a block diagram showing a fuel cell system according to an embodiment of the present invention. 2 is a graph showing a relationship between a control target pressure stored in a pressure limit value database of FIG. 1 and an output of a fuel cell main body. 2 is a flowchart showing a control method of the fuel cell system of FIG. 1. FIG. 4A is a graph showing the change over time of the cooling water pressure during control and non-control of the cooling water pressure in step S4 in FIG. 3, and FIG. 4B is a vehicle corresponding to FIG. It is a graph which shows the time change of an acceleration. FIG. 5A is a graph showing the time change of the pump rotation speed in the step S4 of FIG. 3, and FIG. 5B is a graph showing the time change of the vehicle acceleration corresponding to FIG. 5A. FIG. 6A is a graph showing the time change of the pressure adjustment valve opening degree in the S4 stage of FIG. 3, and FIG. 6B is a graph showing the time change of the vehicle acceleration corresponding to FIG. 6A. . It is a figure which shows the raise of the partial pressure of the cooling water / humidification water in a fuel cell main body by the acceleration of a vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell main body 2 ... Control part (controller)
DESCRIPTION OF SYMBOLS 3 ... Radiator 4 ... Cooling water circuit 5 ... Cooling water pump 6 ... Pressure adjustment valve 7 ... Pressure sensor 8 ... Acceleration sensor 9 ... Acceleration calculation part (vehicle speed sensor)
10 ... Pressure limit value database 11 ... Vehicle

Claims (9)

A fuel cell body that generates electricity by an electrochemical reaction between hydrogen in the fuel gas and oxygen in the oxidant gas;
A water circulation path through which water used when the fuel cell body generates electricity;
A water pressure adjusting unit for adjusting the pressure of the water in the water circulation path;
An acceleration estimator for estimating an acceleration of a vehicle equipped with the fuel cell main body and the water circulation path;
A fuel cell system comprising: a control unit that controls a water pressure adjusting unit according to the acceleration estimated by the acceleration estimating unit.   2. The fuel cell system according to claim 1, wherein the water pressure adjusting unit is a pump that adjusts a circulation amount of the water in the water circulation path by controlling a rotation speed thereof. 3.   2. The fuel cell system according to claim 1, wherein the water pressure adjusting unit is a pressure adjusting valve that adjusts a circulation amount of the water in the water circulation path by controlling an opening degree thereof. 3.   The fuel cell system according to any one of claims 1 to 3, wherein the acceleration estimation unit includes an acceleration sensor that directly detects acceleration in the front-rear, left-right, and vertical directions of the vehicle.   5. The fuel cell system according to claim 1, wherein the acceleration estimation unit further includes an acceleration calculation unit that differentiates a speed of the vehicle to calculate an acceleration in a longitudinal direction of the vehicle. A pressure estimation unit for estimating the pressure of the water;
A pressure limit value database that stores the pressure limit value of the water that is estimated to operate normally.
When the water pressure estimated by the pressure estimation unit exceeds the pressure limit value in the pressure limit value database and the acceleration estimated by the acceleration estimation unit is substantially zero, the control unit The fuel cell system according to any one of claims 1 to 5, wherein it is determined that an abnormality has occurred in the fuel cell system.   7. The fuel cell system according to claim 1, wherein the water circulation path is a cooling water circulation path through which cooling water for cooling heat generated when the fuel cell main body generates power is circulated.   7. The water circulation path according to claim 1, wherein the water circulation path is a humidification water circulation path through which humidified water for humidifying at least one of the fuel gas and the oxidant gas supplied to the fuel cell main body is circulated. The fuel cell system according to claim 1.   2. The fuel cell system according to claim 1, wherein the water pressure is a differential pressure between the water and at least one of the fuel gas and the oxidant gas in the fuel cell main body.