CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0057897, filed May 17, 2019, which is incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to a thermal-activated pressure relief device of a fuel cell vehicle and, more particularly, to a thermal-activated pressure relief device of a fuel cell vehicle, the thermal-activated pressure relief device being able to forcibly discharge hydrogen in a hydrogen tank for safety at a predetermined temperature or more.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

A fuel cell system that is mounted on a hydrogen fuel cell vehicle includes a fuel cell stack that generates electrical energy, a hydrogen supplier that supplies hydrogen that is fuel to the fuel cell stack, an air (oxygen) supplier that supplies air (oxygen), which is an oxidizer in an electrochemical reaction, to the fuel cell stack.

The hydrogen supplier, as shown inFIG. 1, includes a hydrogen tank10, a solenoid valve11mounted at the outlet of the hydrogen tank10and controlling inflow and outflow of hydrogen, a temperature-activated pressure relief device12(referred to as ‘TPRD’) mounted at the outlet of the hydrogen tank10together with the solenoid valve11to forcibly discharge hydrogen to the outside when the temperature of the hydrogen tank10increases, a regulator13reducing the pressure of hydrogen that is supplied from the hydrogen tank10to the fuel cell stack20, etc.

Hydrogen is stored in the hydrogen tank10of the hydrogen supplier by a method of compressing and storing high-pressure hydrogen, and the Maximum Allowable Working Pressure (MAWP) is set up to 875 bar when storing hydrogen to increase the storage amount of the hydrogen in the hydrogen tank10. Accordingly, safety requirements for high-pressure hydrogen stored in hydrogen tanks have been enhanced.

For this reason, the TPRD12is employed as a kind of thermal-activated pressure relief device and has a function of forcibly discharging hydrogen and pressure in the hydrogen tank when the temperature of the hydrogen tank increases to a predetermined temperature of more in preparation for the possibility that if a fire occurs in a fuel cell vehicle, temperature is increased by flames and the internal pressure of the hydrogen tank10is increased, thereby causing the hydrogen tank10to explode.

As the TPRD, in the related art, there are a metal melting/spring type TPRD and a glass bulb TPRD.

If a fire, etc. occurs in a fuel cell vehicle and a hydrogen tank and the surrounding increase in temperature over a reference temperature due to flames, the metal melting/spring type TPRD of the related art operates through a process in which a fusible alloy melts, a process in which the force pressing a spring is removed and a supporting rod is moved forward by the elastic restoring force of the spring, a process in which the piston is unlocked by the forward movement of the supporting rod, and a process in which the piston is moved to open a hydrogen discharge path by the internal pressure of a hydrogen tank.

Accordingly, hydrogen and pressure in the hydrogen tank are forcibly discharged to the atmosphere through the open hydrogen discharge path.

In a metal melting/spring type TPRD, the spring is strongly compressed to lock the piston with large pressure (e.g., 700 bar) applied to the piston from the hydrogen tank and the elastic restoring force of the spring is applied to the fusible alloy. However, indium and bismuth that are the main materials of the fusible alloy are relatively soft metals, so the fusible alloy cannot resist tension of the spring and explodes, whereby there is a possibility of malfunction of the TPRD.

Additionally, the path through which the fusible alloy is discharged and the hydrogen discharge path are separated from each other, so the structure is complicated and a large number of parts are used.

On the other hand, a glass bulb TPRD of the related art includes a hollow body connected to a hydrogen tank, an exhaust cap coupled to an outer end of the hollow body, a piston fastened in the hollow body, and a glass bulb disposed between the exhaust cap and the piston.

In particular, liquid that expands at a predetermined temperature or more is kept in the glass bulb.

Accordingly, if a fire, etc. occurs in a fuel cell vehicle and a hydrogen tank and the surrounding increases in temperature over a reference temperature due to flames, the liquid in the glass bulb overheats and expands, so the glass bulb explodes. Accordingly, the piston is moved forward by the internal pressure of the hydrogen tank, whereby an exhaust hole of the exhaust cap opens and hydrogen in the hydrogen tank is forcibly discharged through the exhaust hole of the exhaust cap.

However, with a glass bulb TPRD, there is a possibility that the TPRD may generate a malfunction such as unexpected forcible discharge of hydrogen if the glass bulb is easily broken by external shock.

In addition, when a separate protective part is added to increase shock resistance of the glass bulb, the machining design of the TPRD is changed by addition of the protective part, so the number of parts increase and the assembly processes increase, thereby increasing the manufacturing cost and the possibility of defects.

The above information disclosure in this Background section is only for enhancement of understanding of the background of the present disclosure, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

SUMMARY

The present disclosure provides, in one aspect, a thermal-activated pressure relief device of a fuel cell vehicle, the thermal-activated pressure relief device enabling downsizing and reduction of the number of parts in comparison to existing TPRDs, being able to smoothly perform the fundamental function of a TPRD, and being able to improve durability and safety and prevent or inhibit a malfunction due to strong resistance against external shock and vibration.

The present disclosure provides a thermal-activated pressure relief device of a fuel cell vehicle, the thermal-activated pressure relief device including: a hollow body mounted at an outlet of a hydrogen tank; a hydrogen discharge block having a plurality of first hydrogen discharge holes and mounted and fixed in an upper portion of the hollow body; a hydrogen discharge pipe having a plurality of second hydrogen discharge holes and connected to a bottom of the hydrogen discharge block; a piston fitted on an outer side of the hydrogen discharge pipe to be able to move up and down and to open and close the second hydrogen discharge holes; a stopper mounted in a lower portion of the hollow body and limiting a downward movement distance of the piston; and a melting alloy disposed between the piston and the stopper and melting at a predetermined temperature or more.

A first female threaded portion may be formed in an upper portion of the hollow body and a first male threaded portion thread-fastened to the first female threaded portion may be formed on an outer side of the hydrogen discharge block.

The first hydrogen discharge holes may be vertically formed through the hydrogen discharge block and arranged with regular intervals along a circumferential edge of the hydrogen discharge block.

The hydrogen discharge pipe may be a pipe with an open lower portion and may be integrally formed on a bottom inside the first hydrogen discharge holes of the hydrogen discharge block.

The second hydrogen discharge holes may be formed laterally through the hydrogen discharge pipe and arranged with regular intervals around the hydrogen discharge pipe.

The stopper may have a second male threaded portion on an outer side thereof to be thread-fastened to a second female threaded portion formed on an inner side of the lower end portion of the hollow body, and may have a third hydrogen discharge hole formed at a center thereof.

A plurality of tool insertion holes for thread-fastening the stopper may be formed on an outer side of the stopper.

An O-ring and a backup ring for hermetically keeping hydrogen may be disposed on an outer side of the piston.

The melting alloy may be a low-melting point alloy of non-lead materials, may keep in close contact with the piston on the stopper when temperature is less than a predetermined level, and may be melted and discharged outside due to downward movement of the piston by discharge pressure of hydrogen when temperature is the predetermined level or more.

The present disclosure provides the following effects from the configuration described above.

First, it is possible to enable downsizing and reduction of the number of parts in comparison to existing TPRDs and to smoothly perform the fundamental function of a TPRD that forcibly discharges the pressure and hydrogen in a fuel tank to the outside at a predetermined temperature or more.

Second, the thermal-activated pressure relief device is strong against external shock and vibration, unlike an existing glass bulb type, so durability and stability can be improved and a malfunction can be inhibited.

Third, the thermal-activated pressure relief device can be used as a safety device for forcibly discharging gas not only in a hydrogen tank, but in LPG, CNG, LNG tanks, etc.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

