JP2001351652A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system which can prevent a cell stack from freezing even under the circumstance of very low temperature, and secure the durability of total system. SOLUTION: For the fuel cell system 1 composed of a plurality of laminated and bound cell, with a cell stack body 7 to which hydrogen gas and air for reaction is supplied, at least the cell stack body 7 is housed in a easing 10, and a heater is arranged inside the wall of the easing 10 or inside the easing 10, and the heater is made to generate heat when the temperature of the cell stack body or the temperature inside the easing become lower than the freezing temperature of generated water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system serving as a power source for a drive motor and a charging source for a secondary battery in an electric vehicle, for example.

[0002]

2. Description of the Related Art Conventionally, a fuel cell system in which hydrogen gas and reaction air are supplied to a cell stack formed by stacking and fastening a plurality of cells to generate electric power by an internal chemical reaction. There is. A fuel cell system such as this is mounted on a vehicle such as a motorcycle, and the electric power generated by the fuel cell system is supplied to a drive motor, and the vehicle is driven by the drive motor.

[0003]

In the case of a vehicle equipped with the above-described fuel cell system, while the fuel cell system is stopped, such as when the vehicle is not running, the temperature of the outside air is below freezing. In this case, the water generated by the power generation in the cell stack body freezes and damages the inside of the cell stack body, which may reduce the durability of the cell stack body and thus the fuel cell system. It may be damaged and become unusable.

[0004] The present invention has been made in view of the above-mentioned conventional problems, and a fuel cell system capable of preventing freezing of a cell stack body even in an extremely low temperature environment and ensuring durability of the entire system. The task is to provide.

[0005]

According to a first aspect of the present invention, there is provided a fuel cell system provided with a cell stack in which a plurality of cells are stacked and fastened and supplied with hydrogen gas and reaction air. The body is accommodated in a casing, and a heater is arranged in the wall of the casing or in the casing. When the temperature of the cell stack body or the temperature in the caging falls below a predetermined freezing temperature of generated water, the heater is heated. The feature is that it is made to be.

According to a second aspect of the present invention, in the first aspect, the heater generates heat by an oxidation reaction when air is supplied,
A regenerative heating element made of an oxidizing / reducing agent that is regenerated by a reduction reaction when hydrogen is supplied, and is characterized by being filled in the wall of the casing.

According to a third aspect of the present invention, in the first aspect, the heater is of an electrothermal type that generates heat when energized.
It is characterized by being disposed in the casing.

[0008]

According to the first aspect of the present invention, the cell stack is housed in the casing, and when the temperature of the cell stack or the internal temperature of the caging falls below the freezing temperature, the heater is heated to generate heat inside the casing. Since the cell stack is warmed, it is possible to avoid a problem that water generated by power generation in the cell stack freezes and damages the inside of the cell stack, thereby lowering the durability of the cell stack and eventually the fuel cell system.

Further, since the cell stack and the like are surrounded by the casing and the heater is heated only when the temperature of the cell stack and the like falls below the freezing temperature, the required amount of heat is small.

According to the second aspect of the present invention, the heater is made of a regenerative heating member, for example, an oxidizing / reducing agent that generates heat by an oxidation reaction when air is supplied and regenerates by a reduction reaction when hydrogen is supplied. It can be used repeatedly without replacing the heat generating member, and does not require a special reduction time by performing the reduction action while the fuel cell is in use.

According to the third aspect of the present invention, since the electric heater is provided, freezing of the cell stack can be easily and reliably prevented, and the freeze preventing structure is simple.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 are views for explaining a first embodiment of the present invention, FIG. 1 is a side view of a motorcycle equipped with a fuel cell drive system of the present embodiment,
FIG. 2 is a schematic diagram of a fuel cell system, and FIG. 3 is a cross-sectional side view of a casing that houses a cell stack body.

Referring to FIG. 2, the fuel cell drive system according to the present embodiment includes a fuel cell system (FC) 1 and a drive unit 2. The power generated by the fuel cell system 1 is used to drive the drive unit 2. By supplying the electric power to the motor 3, the motorcycle 20 shown in FIG. 1 is caused to travel, and a battery (secondary battery) 28 is charged by the electric power. When the power generation capacity of the fuel cell system 1 is insufficient with respect to the output required by the driver's throttle operation, the shortage is compensated for by the electric power from the battery 28.

The driving device 2 converts the electric power supplied from the fuel cell system 1 into a vehicle main controller 2.
a, a DC / DC converter (power adjustment unit) in accordance with an input command from the throttle grip of the motorcycle 20
The power is supplied to the motor 3 via the motor 2b to drive the motorcycle 20, and the battery (secondary battery) 28 is charged by the electric power. 2c
Is a fuse, and TB is a temperature sensor for detecting the battery temperature.

In the fuel cell system 1, hydrogen is supplied to the cell stack 7 by a hydrogen supply system 6, water is circulated and supplied into the cell stack 7 by a water supply system 8, and air for cooling is further supplied. The air is supplied into the cell stack body 7 by the air supply system 9 to generate electricity. The cell stack 7 is formed by laminating a large number of cells made of carbon and sandwiching a polymer film (for example, an ion exchange resin film) with a cooling air passage therebetween. Reference numeral 1a denotes an FC controller that performs various controls of the fuel cell system 1.

The hydrogen supply system 6 supplies the hydrogen in the hydrogen cylinder 17 to the cell stack body 7 via a shut-off valve 18, a flow control valve 19, and a buffer tank 40. The fuel is burned at 41 and discharged to the outside. Reference numeral 42a denotes an open / close valve, Ta denotes a temperature sensor for detecting the temperature in the casing 10, Tc denotes a temperature sensor for detecting the temperature in the cell stack 7, and Ao detects a current value supplied from the cell stack 7. A current sensor, V is a voltage sensor for detecting a voltage between both ends of the cell stack 7, and 5 is a backflow prevention diode.

The water supply system 8 is provided with a water pump 44 for cooling and humidifying the water in the water tank 43 so that the cell stack 7 is cooled.
Water, and the water passing through the heat exchanger 4
5 so as to return to the inside of the water tank 43.

The air supply system 9 has a ventilation passage 25b to be described later.
Is introduced around the battery 28 and the cooling fan 31 disposed in the ventilation passage 25b.
Is supplied to a moisture recovery heat exchanger 45 via a switching valve 38, and the air from which moisture has been removed to become dry air is supplied into the cell stack body 7 by a blower 46. I have. The water separated from the outside air is collected in the water tank 43.

The fuel cell system 1 and the driving device 2 are mounted on a motorcycle 20 shown in FIG. 1. The motorcycle 20 has the following general structure. Body frame 21
Connects a pair of left and right side pipes 21c, 21c to the lower end of a main pipe 21b extending obliquely downward from the front end of the head pipe 21a.
1c is extended substantially horizontally rearward to form a low-floor footrest 21d, which is further extended obliquely rearward and upward.

A front fork 22 is pivotally supported by the head pipe 21a so as to be steerable left and right. A front wheel 23 is pivotally supported at a lower end of the front fork 22, and a steering handle 24 is fixed to an upper end. A seat 30 is mounted above the side pipe 21c, and the periphery of the front fork 22 and the left and right sides of the body frame 21 are surrounded by a resin body cover 25 made of resin.

A unit swing type motor unit 2 is formed by an obliquely upward extension of the side pipe 21c.
6 is pivotally supported, and a rear end of the motor unit 26 is pivotally supported by a rear wheel 27. The motor unit 26 is formed by integrally connecting the motor 3 whose axis is oriented in the vehicle width direction and a transmission case 29 extending rearward on the left side of the vehicle.

Further, support frames 21e, 2 erected between the left and right foot rests 21d, 21d of the body frame 21 are provided.
1e, the cell stack 7 of the fuel cell system 1
Further, a casing 10 accommodating the battery 28 and the like of the driving device 2 is mounted. In FIG. 3, the illustration of the contents is omitted. The water tank 43 is provided above the casing 10, and the hydrogen cylinder 17 is provided at the rear of the vehicle body.
Is installed. Reference numeral 18 denotes an on-off valve, and 19 denotes a pressure regulating valve.

In the vehicle body cover 25, a wind guide passage 25b for introducing a traveling wind toward the casing 10 is formed, and a wind guide opening 25a of the wind guide passage 25b is opened toward the front of the vehicle. I have. The cooling fan 31 is arranged at an inlet of the casing 10 in the air guide passage 25b. 100 is a small hole for discharging excess air. Note that the cooling air that has exited the casing 10 is discharged to the outside through the outlet 25d through the outlet 25c in which the hydrogen cylinder 17 is disposed.

The caning 10 comprises a storage section 11 having an opening 11a at an upper portion, and a lid 12 mounted on the storage section 11 such that the opening 11a can be opened and closed by a hinge 12a. Reference numeral 12c is a lock for fixing the lid 12 in a closed state.

The storage portion 11 and the lid 12 are a double-walled storage frame 11a made of stainless steel plate or the like, and an iron powder 11 functioning as an oxidizing / reducing agent in a lid frame 12a.
b, 12b, and the storage frame 1
The switching valve 38 is embedded in the double wall 1a.

The switching valve 38 includes a main port 38 a communicating with the cell stack 7, a ventilation port 38 b for supplying ventilation air into the casing 10, and a casing 10.
The panel has a heat generating port 38c for supplying air for oxidizing the internal oxidizing / reducing material, and the outside air from the cooling fan 31 is appropriately switched and supplied to each port. In addition,
An exhaust pipe 39a exhausts air from between the heat exchanger 45 and the water tank 43, an exhaust pipe 39b exhausts ventilation air supplied from the ventilation port 38b into the casing 10, and 39b.
c is a communication hole that communicates the inside of the storage frame 11a and the inside of the lid frame 12a.

Reference numeral 39d denotes a hydrogen supply port for supplying hydrogen for reduction to the iron powders 11b and 12b filled in the double wall. The hydrogen cylinder 17 is connected to the hydrogen supply port 39d via the buffer tank 40 by a hydrogen supply pipe 39f provided with an electromagnetic on-off valve 39e.

A temperature sensor 50a and a hydrogen concentration sensor 50b are provided in the wall of the storage frame 11a. Further, a water reservoir 51 having a drain valve 51a is provided on a bottom wall of the storage frame 11a. In addition,
When the oxidizing air is supplied into the double wall, the drain valve 51a is opened to facilitate the supply of the air.

Next, the operation and effects of the present embodiment will be described. When the motorcycle 20 starts traveling, first, the drive motor 3 starts driving the rear wheels by the electric power of the battery 28. Then, when certain conditions are satisfied, the fuel cell system 1 starts. In this case, the reaction water is supplied to the water passage of the cell stack 7 and the hydrogen cylinder 1
The hydrogen gas in 7 is supplied to the hydrogen gas passage of the cell stack 7. As described above, the reaction water and the hydrogen gas are supplied to the cell stack body 7, electricity is generated by a chemical reaction in the inside, the electricity is supplied to the drive motor 3, and the battery 28 is charged.

A part of the traveling wind passes through the casing 10 and is discharged from the air discharge port 25d. The temperature of the cell stack 7 is always read by the FC controller 1a. When the temperature of the cell stack becomes a predetermined value or more, the controller 1a starts the cooling fan 31,
The traveling wind is also supplied into the cooling passage of the cell stack body 7,
The cell stack 7 is kept in a temperature range suitable for the chemical reaction.

In the present embodiment, the temperature of the cell stack 7 detected by the temperature sensor Tc or the temperature of the temperature sensor 5
When the temperature inside the wall of the casing 10 detected at 0a falls below a preset freezing temperature, for example, zero degree, the controller 1a closes the switching valve 38, closes the ventilation port 38b and the main port 38a, and Heating port 38
c to the open position and the exhaust valve 51a
open. At this time, the cooling fan 31 is started.

As a result, outside air is supplied into the wall of the casing 10, and the internal iron powders 11b and 12b are oxidized and generate heat, and the inside of the casing 10 is warmed by the generated heat. When the temperature of the cell stack or the temperature in the wall rises above the freezing temperature by a predetermined value or more, the controller 1a closes the heating port 38c of the switching valve 38 and stops the supply of the oxidizing air. Thereby, the iron powders 11b, 12
The heat generation of b stops.

The supply of the oxidizing air into the wall may be automatically stopped when a predetermined time has elapsed from the start of the supply.

When the number of times of the supply of the oxidizing air reaches a predetermined value, or when the temperature in the wall hardly rises despite the supply of the oxidizing air, the iron powders 11b and 12b are reduced. Will be This is because the controller 1a opens the electromagnetic on-off valve 39e when the above conditions are satisfied, and thereby hydrogen gas is supplied to the iron powders 11b and 12b in the wall.

As a result, the oxidized iron powder 11b, 12
b is reduced and regenerated to a state before heat generation, and heat can be generated again. At this time, when the hydrogen concentration detected by the hydrogen concentration sensor 50b reaches a predetermined value, the supply of the hydrogen gas is stopped, assuming that the reduction step has been completed. The water generated by the reducing action is stored in the water reservoir 51 and is discharged through a drain valve 51a.

As described above, in the present embodiment, when the temperature inside the cell stack falls to the freezing temperature, the casing 1
Since the temperature inside the cell stack body 7 is increased, the reaction water in the cell stack body 7 freezes and damages the inside of the cell stack body 7, thereby lowering the durability of the cell stack body 7 and thus the fuel cell system. Avoid problems.

The double wall of the casing 10 is filled with an oxidizing / reducing agent, oxidized by the supply of air to generate heat, and the oxidization is reduced by the supply of hydrogen gas to return to the state before oxidation. Since the heat generation and the regeneration are configured to be repeated, the heat retaining structure in the casing is extremely simple, and the cost increase can be avoided.

Here, in the above embodiment, the entire fuel cell system is kept warm. However, as shown in FIG. 4, only the cell stack 7 may be surrounded by a casing. 4, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

In FIG. 4, the casing 10 'is configured to surround only the periphery of the cell stack 7;
The casing 10 'is filled with iron powder 11b.
The on-off valve 39e and the hydrogen supply pipe 39
Hydrogen can be supplied via f.

Also in this embodiment, when the inside of the casing or the cell stack falls below a predetermined freezing temperature, air is supplied to the iron powder 11b, and the iron powder 11b generates heat to raise the temperature of the cell stack 7. . And, when predetermined conditions such as hardly generating heat even when air is supplied are satisfied,
Hydrogen is supplied to the iron powder 11b to reduce the iron powder 11b.

In the case where only the temperature of the cell stack is increased, the freezing of the cell stack 7 is prevented in the same manner as in the above-described embodiment, and the durability of the cell stack is reduced. Can be avoided.

In each of the above embodiments, the case where the wall of the casing 10 is filled with iron powder (oxidizing / reducing material) has been described as a structure for raising the temperature inside the casing 10. Is not limited to an oxidizing / reducing material as shown in FIG. In FIG. 5, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts.

In FIG. 5, the housing 1 of the casing 10
Heat insulation materials 11b 'and 12b' are filled in the walls of the housing 1 and the lid 12, and an electric heater 52 is provided on the bottom surface. Incidentally, 52a is an on / off switch.

In this embodiment, when the temperature in the cell stack or the temperature in the casing falls below a predetermined freezing temperature, the controller controls the on / off switch 52a to turn on / off the heater 52 to generate heat, thereby raising the temperature in the casing. Let it. As a result, similarly to the above-described example, it is possible to prevent the cell stack body 7 from being damaged by freezing and from being deteriorated in durability.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle equipped with a fuel cell system according to a first embodiment of the present invention.

FIG. 2 is a block diagram of the fuel cell system.

FIG. 3 is a sectional side view of a casing that houses the fuel cell system.

FIG. 4 is a block diagram of a modification of the first embodiment.

FIG. 5 is a sectional side view of a casing according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fuel cell system 7 Cell stack body 10 Casing 11b, 12b Iron powder (regenerative heating member-oxidation / reduction material) 52 Electric heater

Claims (3)

[Claims] 1. A fuel cell system comprising a cell stack in which a plurality of cells are stacked and fastened and supplied with hydrogen gas and reaction air, at least the cell stack is housed in a casing, and A fuel cell, wherein a heater is disposed in a wall or in the casing, and the heater generates heat when the temperature of the cell stack or the temperature in the caging falls below a freezing temperature of a predetermined generated water. system. 2. The casing according to claim 1, wherein the heater is a regenerative heating member made of an oxidizing / reducing agent that generates heat by an oxidation reaction when air is supplied and regenerates by a reduction reaction when hydrogen is supplied. A fuel cell system, wherein the fuel cell system is filled. 3. The fuel cell system according to claim 1, wherein the heater is of an electrothermal type that generates heat when energized, and is disposed in the casing.