JP6414751B2 - Shock bumper for fuel cell vehicles - Google Patents

Description

Detailed Description of the Invention

  The present invention relates to a safety means for preventing a disaster caused by hydrogen leakage from a fuel cell vehicle main body with a shift from a current gasoline vehicle to a fuel cell vehicle using hydrogen as fuel.

  Fuel cells that are expected to be the next generation clean energy source are already on the market with fuel cell vehicles equipped with these batteries. Hydrogen used as fuel for the fuel cell is stored in a high-pressure hydrogen cylinder mounted in the vehicle, and is supplied to the fuel cell through a pressure-reducing valve from there to be converted into power electricity.

  Hydrogen has extremely unique properties compared to gasoline, which is a conventional fuel. In other words, if there is any ignition source due to leakage in the air, the hydrogen concentration in the air will explode in the range of 4 to 75% by volume, and its ignition energy is extremely small at 0.02mJ, which is much higher than gasoline. It is an easy substance.

  On the other hand, the specific gravity of hydrogen is as light as about 1/15 that of air and diffuses easily in the air. When handling hydrogen, it is important for safety to diffuse hydrogen to the atmosphere as quickly as possible so that it does not stay in the vicinity of the vehicle if hydrogen leaks due to a collision accident or the like.

Further, as one of the safety measures, there is a method of reducing combustion energy by using a hydrogen / nitrogen mixed gas instead of the hydrogen composition alone. For example, the following documents are published.
JP 2004-146212 A JP 2004-220802 A JP 2006-207785 A

  Documents 1 and 2 describe a method of transporting hydrogen as a mixed gas of hydrogen and nitrogen using a conduit from a hydrogen production plant to a hydrogen station instead of using a conduit. Document 3 describes a method of filling the fuel cell vehicle with hydrogen by separating the mixed gas into hydrogen and nitrogen by a simple method at a hydrogen station.

  Several safety measures have already been taken for fuel cell vehicles on the market. For example, use a hydrogen cylinder that can withstand ultrahigh pressure of 70 MPa (= megapascals) using carbon fiber, make sure that the seat space is completely isolated from the space where hydrogen is handled, and place a hydrogen gas detector in the vehicle. For example, an alarm is issued when a leak occurs.

  On the other hand, further strengthening of safety measures is in progress for the future. One of the most important issues is the development of new hydrogen storage technology that replaces the current high-pressure storage system. In order to efficiently store hydrogen in a limited space inside the vehicle, the current method is to store hydrogen in a high-pressure gas in a hydrogen cylinder, and this method is also used for all prototypes including commercial vehicles. .

  However, if you encounter an accident such as a collision or falling floor while driving, the probability of occurrence is low, but the hydrogen cylinder itself and its related parts, for example, the path and parts leading from the hydrogen cylinder to the fuel cell are damaged, and hydrogen leaks. The potential danger has not yet been completely eliminated.

  At present, as countermeasures against this, a countermeasure is taken to guide the leaked hydrogen to the outside air by further enclosing the relevant hydrogen pipes and parts with an outer pipe to form a double pipe. However, if the outer tube itself is damaged by the impact at the time of the collision, hydrogen diffuses in the vicinity of the fuel cell vehicle, and there is a risk of causing an explosion at some ignition source.

  For example, a fuel cell vehicle equipped with 4 kg of hydrogen encounters an accident when hydrogen damage is assumed, and the entire amount of hydrogen leaks and diffuses hemispherically around the vehicle. It has been reported that when it is ignited and generated, the range of about 7 m in radius centered on the car is exposed to high temperatures exceeding 500 degrees due to the heat of combustion.

  The probability of such an accident occurring on a general ground road is very low, but if it occurs in a closed space such as an underground tunnel or a long tunnel, it may cause serious damage. For this reason, strict regulations have been imposed by the relevant government agencies regarding the travel of fuel cell vehicles in the tunnels, and the passage of each tunnel is approved for passage.

  Furthermore, in recent years, there has been a movement toward full-scale automatic driving of cars in the automobile industry, which is a completely different point of view. Autonomous driving means automating the driving of a car and driving it to its destination unattended. Fuel cell vehicles are also expected as the main model of the next eco-car in this field. When considering safety measures for fuel cell vehicles based on the above background, it is necessary to select means that can be applied to future automatic driving.

  The present invention has been made in view of the above problems. In a fuel cell vehicle having a shape assumed by the inventor, the present invention has focused on an impact buffer bumper, which is an important safety component, and has been improved. Provide a means to reduce human damage as much as possible even in the event of an accident.

  First, the overall configuration of the present invention will be described. The present invention is roughly composed of a shock absorbing bumper, a storage chamber (hereinafter referred to as a storage chamber) for storing a hydrogen cylinder and a fuel cell, and related parts thereof. The outline is shown in FIG.

First, the shape and location of an impact buffer bumper (= hereinafter referred to as a nitrogen bumper ) filled with nitrogen gas will be described. The nitrogen bumper has a cylindrical shape and is attached in a belt shape over the entire outer periphery of the fuel cell vehicle body. In FIG. 1, the nitrogen bumper is displayed as a circle before and after the vehicle in order to easily understand the connection with related equipment.

Although all the conventional bumpers are disposed at the front and rear of the vehicle, it is a major feature of the present invention that the nitrogen bumper is attached to the entire outer periphery of the vehicle. Nitrogen bumpers installed on the entire circumference of the vehicle can disperse the stress during impact over the entire circumference. At this time, all the wheels of the vehicle are mounted inside the nitrogen bumper . The nitrogen bumper is filled with nitrogen gas (= hereinafter abbreviated as nitrogen) so as to maintain a pressure of, for example, about 0.10 to 1.00 MPa.

Second, the material of nitrogen bumper and its accessories are described. The main material of the nitrogen bumper is synthetic rubber or synthetic resin, and has elasticity so that it can be deformed by impact such as collision. A pipe for sending nitrogen into the storage chamber is attached to the nitrogen bumper, and a nitrogen discharge valve and an orifice for limiting the discharge amount (hereinafter referred to as a restriction orifice) are attached to the pipe. In addition, a pressure detector that can detect the pressure inside the nitrogen bumper is installed in the same pipe.

The nitrogen release valve refers to a valve that opens when the pressure in the nitrogen bumper reaches a set value or more. Unlike a general spring-type safety valve, the nitrogen release valve is configured to maintain the open state as it is once operated. The set value of the pressure for opening the nitrogen release valve is selected from values in which the pressure of the nitrogen bumper is increased, for example, by 1.1 to 2.0 times the filling pressure due to a collision or the like.

The restriction orifice is provided to adjust the amount of nitrogen released in the nitrogen bumper , and its purpose is to adjust the nitrogen release time so that the passenger can safely escape from the vehicle in the event of an accident. At the same time, the storage chamber body is prevented from being damaged due to abrupt release of nitrogen from the nitrogen bumper .

  In addition to the system that operates by the pressure detector described above, a nitrogen release valve that opens when the hydrogen concentration reaches a set value is detected by a hydrogen detector installed in the storage chamber. . The mechanism for operating the nitrogen release valve is the same as that of the pressure detection method described above, but the set value for opening the nitrogen release valve is a value selected from, for example, 1.0 to 4.0 vol% in terms of hydrogen concentration. FIG. 2 shows the configuration of the devices related to the two types of detection methods together with the detection method of the previous section.

In addition, the storage room will be equipped with a pipe that discharges nitrogen released into the storage room to the atmosphere together with the gas in the storage room, a rupture disk (= rupture desk), and a vent pipe. To prevent hydrogen explosion in the storage room, always keep a nitrogen atmosphere in normal times. In order to maintain this nitrogen atmosphere, a rupturable plate is attached, and the pressure in the storage chamber is constantly maintained at about several hundred mm water column.

When nitrogen is released from the nitrogen bumper into the storage chamber due to a collision or the like, the pressure in the storage chamber rises and the rupturable plate is broken, and the gas in the chamber is vented to the atmosphere together with nitrogen through the vent pipe. The diameter of the vent pipe should be large enough to prevent the storage chamber from becoming overpressure.
In addition, vent piping is not described in FIG.

In the present invention, focusing on a bumper which is one of the safety parts of a fuel cell vehicle, a new bumper (= nitrogen bumper) filled with nitrogen gas is installed in place of the conventional bumper to strengthen the role of shock buffering such as collision. . On the other hand, automatic driving of cars is attracting attention as a new issue in the automobile industry. In automatic driving, it is important to further strengthen the vehicle body in terms of hardware in addition to measuring automation through unmanned driving. The present invention can be expected to lead to enhancement of safety also fuel cell vehicle body Oite in this new field.

First, the nitrogen filling amount of the nitrogen bumper will be described. The amount of hydrogen to be mounted on the hydrogen cylinder the current fuel cell vehicles will depend to a large can of and pressure in the tank is about 50 Nm ₃ back and forth up. Therefore, the amount of hydrogen that must be released from the fuel cell vehicle to the atmosphere using nitrogen in a collision or the like is 50 Nm ₃ .

  When releasing nitrogen into hydrogen, if the mixing rate of nitrogen increases, the combustion heat of hydrogen decreases and it is safe. In safety engineering, if the mixing ratio of nitrogen in hydrogen exceeds 50%, even if the mixed gas leaks into the air and ignites, the most dangerous detonation phenomenon (= intense explosion with shock waves) It is said that it can be avoided.

Therefore, judging from the above hydrogen loading amount, the target value of the nitrogen filling amount is 50 Nm3 which is the same as the above hydrogen loading amount. Assuming a case in which a nitrogen bumper is attached to the entire outer periphery of the current fuel cell vehicle with respect to this value, for example, when the specification of the nitrogen bumper is 10B in diameter, 10 m in length, and 1 MPa in filling pressure, the nitrogen filling amount is about 5. 1Nm3. This is only about 10% of the target value.

In order to increase the filling amount of nitrogen, it is necessary to increase the filling pressure of the nitrogen bumper. However, if the pressure is increased too much, the elasticity of the nitrogen bumper is reduced, and the original function of the bumper is impaired. Although the above numerical values have not reached the target value at present, this value is unavoidable at the initial stage of nitrogen bumper introduction. In the future, this ratio will be brought closer to the target value by improving the elasticity of the nitrogen bumper by developing new materials and increasing the amount of nitrogen filled, and by reducing the amount of hydrogen loaded by improving the fuel consumption of fuel cell vehicles. Is possible.

Second, the amount of nitrogen released from the nitrogen bumper will be described. The amount of nitrogen released from the nitrogen bumper is determined in consideration of the release time required for all passengers to safely escape from the vehicle in the event of an accident. Since the release time depends on the release rate of nitrogen from the nitrogen bumper, it is necessary to adjust the release rate of nitrogen by some means in order to determine the release time. Therefore, a restriction orifice is attached to the nitrogen gas discharge path to adjust the amount of nitrogen released.

For example, if there are four passengers and the escape time per person is assumed to be about 30 seconds, it is necessary to continuously release nitrogen for two minutes in order for all four passengers to escape from the vehicle. In the actual calculation of the orifice diameter, for example, the diameter is determined so that 80% of the nitrogen holding amount in the nitrogen bumper can be released in 2 minutes. Further, as described above, this restrictive orifice also serves to prevent the storage chamber from being damaged by the sudden release of nitrogen from the nitrogen bumper .

Third, the release conditions from the nitrogen bumper are described. Nitrogen release valve from nitrogen bumper selecting the two types of operating by detecting the hydrogen concentration in the storage chamber and as described above, the type operating by detecting the pressure of the nitrogen bumper. Furthermore, both types of operating factors are independent factors.

  In creating a software surface (= logic circuit) that determines the nitrogen release condition, the above-mentioned operating factors are connected not by an “AND circuit” but by an “OR circuit”. Connecting with an “OR circuit” means that nitrogen is released if either of the operating factors is activated. If hydrogen is leaked by this connection, the probability of overlooking the leak can be greatly reduced.

Fourth, the shape of the nitrogen bumper is described. The shape of the fuel cell vehicle that is currently being prototyped is mostly a rounded rectangle when viewed from above. Since the nitrogen bumper is attached along the outer periphery, the shape thereof is a rectangle similar to the shape of an automobile.

  One of the distinguishing features of fuel cell vehicles compared to conventional gasoline vehicles is the freedom of vehicle design. In other words, fuel cell vehicles do not require a mechanical transmission that transmits the engine power, which is indispensable to gasoline vehicles, to the wheels, and the power from the fuel cells is transmitted to a power motor (= wheel) at an arbitrary position using an electric cable. be able to.

If this feature is utilized, the shape of the vehicle can be easily changed from the conventional rectangle to another shape. For example, the shape that can withstand mechanical impact from the outside is an ellipse that is rounder than a rectangle. The arrangement of nitrogen bumpers having this shape is shown in FIG. In the figure, the upper row shows the arrangement of seats as viewed from above, the middle row shows a side view, and the lower row shows the arrangement of wheels as seen from the bottom.

Furthermore, it is also possible to make the shape a circle that is most resistant to external impacts. This shape is shown in FIG. The upper seats can be seated facing each other by rotating the seat during automatic driving. The lower wheel rotates the tire axle 180 degrees to the left and right to advance the vehicle in any direction of east, west, south, and north, and the minimum turning radius of the vehicle can be brought close to zero . In addition, the number of wheels is sufficient to travel with 3 wheels as well as 4 wheels. The design with the number of wheels of a passenger car as described above is only possible for an electric vehicle including a fuel cell vehicle, and cannot be realized with a conventional passenger vehicle using gasoline.

The length of the outer circumference per vehicle residential area Using nitrogen bumper of the present invention such a circular shape to the bumper of the vehicle retaining is minimal compared to other shapes. As a result, the length of the nitrogen bumper decreases and the amount of nitrogen filling decreases, but the shortage can be dealt with by increasing the diameter of the nitrogen bumper or increasing the nitrogen sealing pressure.

When the vehicle has a circular structure, the greatest advantage is that the strength of the vehicle body can be maximized against an external impact. A vehicle having this shape can greatly contribute to ensuring the safety of passengers when it is assumed that the vehicle will automatically run in the future. 3 and 4 are for easy understanding of the arrangement of the nitrogen bumper , and a part of the drawing is simplified.

As a safety measure for fuel cell vehicles, the present invention focuses on a shock-absorbing bumper from among a number of parts, and in addition to nitrogen in order to cope with the current trend of automatic driving of vehicles, which has recently become a new topic in the automobile industry. We proposed a new bumper (= nitrogen bumper ) encapsulating The shape of the vehicle to which the nitrogen bumper is attached is oval or circular, and the appearance is similar to a “bumper car” at a glance. However, although the appearance is similar, the novelty of the present invention is not impaired. This is because the nitrogen bumper is an invention effective only for a fuel cell vehicle equipped with hydrogen.

The supplementary contents detailed in the specification regarding the present invention are summarized as follows.
(!) The subject of the present invention is a fuel cell vehicle, particularly a fuel cell vehicle having a circular outer periphery.
(2) The shape of the bumper of the present invention is cylindrical, has a space inside, and is installed around the entire circumference of the vehicle.
(3) Fill the bumper with nitrogen gas, release nitrogen at the time of collision, and drive out hydrogen outside the vehicle.
(4) The next target of the present invention is a bumper for a fuel cell vehicle used for automatic driving of a vehicle.

  Whether or not the present invention is used in the industry is greatly influenced by the movement of current times in the first half of this century. As for fuel cell vehicles, the sale of utility vehicles began in Japan last year in 2014. This car is called the “ultimate eco-car” that does not emit any carbon dioxide, and has attracted attention from the world as one of the effective means of preventing global warming.

  However, there are still some challenges for this car to spread in earnest. Examples include the development of a hydrogen station for supplying hydrogen to fuel cell vehicles, the development of a new hydrogen storage method that replaces the current ultrahigh pressure cylinders, and the development of a new catalyst that replaces platinum used in fuel cells.

  On the other hand, a new challenge for this century is the automatic driving of cars. In recent years, not only the world's automakers but also IT companies have participated in this case, and a fierce battle has started. It has been reported that this problem will start running on prototype roads as well as expressways within five years at the earliest. This is the beginning of the “day of traveling with automatic driving”.

  Further, as described above in the background section of the specification, hydrogen is an environmentally clean gas, but is also a very dangerous substance for safety. Many lives have been lost in hydrogen accidents in the past. In the future, if new demand is stimulated, new disasters may be induced. The most economical and effective means for this protection is “adoption of nitrogen”. Hiring means introducing ideas that have been overlooked. Nitrogen help is absolutely necessary to prevent fire and explosion accidents caused by hydrogen.

  It is said that the 21st century is the era of hydrogen, and the key to its realization is the construction of a hydrogen infrastructure. This outlook isn't wrong, but it looks a bit like one hand. If you are seriously aiming for the arrival of the hydrogen era in the first half of this century, it is essential to build a nitrogen infrastructure in parallel with the construction of the hydrogen infrastructure.

Furthermore, the problem which must be solved also remains in the present invention. That is, how to replenish nitrogen filling the fuel cell vehicle's nitrogen bumper and storage room. Nitrogen stored in nitrogen bumpers and storage rooms must be easily replenished whenever and wherever needed. The construction of the nitrogen infrastructure has led to the solution of this problem.

  Under the circumstances described above, the present invention pays attention to two problems of “spread of fuel cell vehicles” and “realization of automatic driving of vehicles” and proposes adaptation measures thereof. The key word common to both issues is safe. If the environment surrounding the automobile industry develops in the first quarter of the 21st century as the inventors think, the possibility that the present invention can exert its effects can be fully expected.

Ru schematic view showing the arrangement of a new bumper in a fuel cell vehicle.   It is a figure which shows the operating factor of the new type bumper in a fuel cell vehicle.   It is the schematic of the fuel cell vehicle which makes the outer periphery of a car elliptical   It is the schematic of the fuel cell vehicle which makes the outer periphery of a vehicle circular.

1 Driver's seat 2 Impact bumper bumper (= Nitrogen bumper )
3 Hydrogen cylinder 4 Fuel cell 5 Hydrogen cylinder and fuel cell storage room (= storage room)
6 Nitrogen release valve 7 Restriction orifice 8 Rupture disc (= Rupture Desk)
9 Vent piping 10 Electric motor 11 Electric cable 12 Tire 13 Pressure detector 14 Hydrogen detector 15 Tire axle

Claims (4)

This is a safety measure to protect a fuel cell vehicle from a fire explosion caused by hydrogen leakage at the time of collision. A hydrogen cylinder, a fuel cell and related parts are stored in a nitrogen atmosphere storage room completely isolated from the seat of the fuel cell vehicle. Furthermore, an elastic cylindrical bumper is attached to the entire circumference of the outer periphery of the vehicle body, the interior is filled with nitrogen gas, and the pressure inside the bumper is controlled by a pressure detector installed in a pipe that leads from the bumper to the storage chamber due to a collision or the like. When it is detected that it has risen above the set value, the nitrogen release valve installed in the pipe is opened to release the nitrogen gas in the bumper to the storage room, and the gas in the storage room is passed through a vent pipe that leads to the atmosphere from the storage room. An impact buffer bumper for a fuel cell vehicle, characterized by being released into the atmosphere together with nitrogen gas.   When the hydrogen detector installed in the storage chamber of the fuel cell vehicle detects that the hydrogen concentration in the storage chamber has risen above the set value, the nitrogen release valve installed separately from the nitrogen release valve is opened. The shock-absorbing bumper according to claim 1, further comprising a function of   The shock absorbing bumper according to claim 1, wherein a restriction orifice capable of adjusting a flow rate of nitrogen gas discharged from the bumper adjacent to the nitrogen discharge valve is provided in a pipe extending from the bumper to the storage chamber. .   The shock-absorbing bumper has a circular or oval outer periphery of the vehicle, and is provided on the entire outer periphery of the fuel cell vehicle that can advance the vehicle in an arbitrary direction by rotation of a tire axle. The bumper for shock absorption according to claim 1.

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