HK1129912A - Safety warning and shutdown device and method for hydrogen storage containers - Google Patents

Description

Safety warning and shut-down apparatus and method for hydrogen storage containers

Technical Field

A safety mechanism for an on-board hydrogen storage and supply system designed for delivering hydrogen to a vehicle driveline is disclosed. The mechanism provides a safety warning and shutdown system and method for a hydrogen storage device.

Background

Hydrogen is the most abundant element in the universe and can be a major energy source. Hydrogen has become increasingly recognized as a future fuel because it can produce a number of environmental benefits and can be produced from a wide variety of fossil and renewable energy sources. Hydrogen can be stored chemically or by adsorption means in compressed form or in liquid form or in solid state.

There are three basic requirements for hydrogen storage systems: (1) the ability to receive fuel from an external source; (2) providing sufficient storage capacity to allow the powertrain to provide a sufficient range of travel for the vehicle; and (3) supplying fuel to the powertrain at a requested rate, as needed.

However, storage of hydrogen is challenging due to its low energy density. Currently, one way in which hydrogen can be stored is by storing it in a high pressure vessel. These containers must be large and can withstand stress and strain during each pressurization cycle, resulting in material fatigue and reduced strength.

Current compressed hydrogen on-board storage systems are designed to support 750 to 1,000 fill cycles per year, and last for a period of about 15-20 years. The pressure vessel was tested to support 15,000 leaks and no rupture cycles and continued for an additional 30,000 no rupture cycles. Given the 200 mile range of each fill, the current requirements amount to 150,000 to 200,000 miles per year, resulting in considerable over-design and resulting weight and cost penalties on the container design. Thus, current container designs are not cost effective.

This industry continues to encourage over-design as the only means of ensuring safety when a well-defined mechanism does not exist to ensure that a system that exceeds the cycle life is positively considered to have failed. This can result in higher costs for production and maintenance of the on-board hydrogen storage and supply system.

Disclosure of Invention

The present invention provides an alternative cost-effective safety feature for on-board hydrogen storage containers that is an improvement over the prior art by eliminating the need for over-design. A system and method including a fill cycle counter with a driver warning and shutdown system is disclosed.

In one implementation, a safety warning and shutdown system and method for a hydrogen storage container is disclosed, comprising: a valve attached to the container, the valve having a check valve, an electrical solenoid, a pressure transducer, and a temperature transducer for filling the hydrogen storage container; a sensor for monitoring the number of fill cycles; and a shut-off device for stopping further use of the hydrogen system after a predetermined limit of the number of filling cycles is reached.

In an exemplary implementation, the sensor is a strain gauge disposed in the fuel container. The strain gauge may be a number of different gauges known in the art. In one implementation, the sensor comprises a strain gauge that measures strain in the container using an embedded optical fiber. In another implementation, the sensor is a mechanical strain gauge that measures strain in the container. In yet another implementation, the sensing system incorporates an acoustic emission generator and receiver to monitor structural strain caused by pressurizing the container.

In other implementations, the safety warning and shutdown systems and methods incorporate sensors into the valve. In one exemplary implementation, the strain gauge includes a diaphragm located in the valve.

In a further embodiment, the system includes a warning device to notify a user of the vehicle that the system is approaching a predetermined limit.

In still other implementations, software and hardware measurements are utilized to prevent tampering with the system when the system reaches predetermined limits.

The safety warning and shutdown system may also include a controller that counts the number of fill cycles. In an exemplary embodiment, the fill cycles are counted each time the hydrogen container is filled above 90% of the rated pressure or mass.

In other exemplary implementations, the controller deactivates the electrical solenoid to disable the valve and prevent further use of the hydrogen system after the number of fill cycles has reached a predetermined number. The controller may also deactivate the check valve to disable the valve and prevent further use of the hydrogen system after the number of fill cycles has reached a predetermined number.

In an exemplary embodiment, the controller is an engine control unit. In other embodiments, the controller is a separate microprocessor attached to the hydrogen container or mechanical counter.

Other objects, features and advantages of the present invention will become apparent from the ensuing description and appended claims.

Drawings

The above mentioned features and objects of the present invention will become more apparent by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers refer to like elements, and in which:

FIG. 1 is a perspective view illustrating a hydrogen storage system incorporating the device of the present invention integrated into a container valve;

fig. 2 is a perspective view illustrating details of a container valve incorporating the device of the present invention.

Fig. 3 illustrates one implementation of a hydrogen storage system depicting a metal strain gauge present in the container.

Fig. 4 illustrates another implementation of a hydrogen storage system depicting a fiber optic embedded strain gauge present in the container.

Fig. 5 illustrates another implementation of a hydrogen storage system depicting a fiber optic embedded strain gauge present in the container.

Fig. 6 illustrates a close-up view of a valve in a hydrogen storage system depicting a pressure transducer port present in the valve.

Fig. 7 illustrates a system block diagram of a hydrogen storage container safety and shutdown system in accordance with the present invention.

Detailed Description

The present invention provides an alternative cost-effective safety feature incorporating a fill cycle counter with a driver warning and shutdown system 5. The system 5 monitors the number of times the hydrogen container 10 is filled and then takes action at a predetermined termination point. The sensor 40 monitors each time the hydrogen container 10 is filled to more than 90% of the rated pressure or mass. Once the predetermined service life is reached, the disclosed device/direction will disable the valve 12 or refueling mechanism so as to shut off the fuel supply to the vehicle and make the container 10 non-refillable. This may substantially ensure that the useful life of the container 10 is over.

In the exemplary implementation of the closure device and system 5 illustrated in fig. 1, the shutoff valve assembly 12 is attached to the walls of the containers 10, 12. The container 10 is mounted on a vehicle that utilizes hydrogen as a fuel. For example, a typical container 10 for on-board hydrogen storage is designed to have a pressure rating of about 5000 to 10,000 psi.

As illustrated in FIG. 2, an exemplary valve assembly 12 includes an electrical solenoid shut-off valve 14, a pressure transducer 16, a temperature transducer 18, and a check valve 20. The valve 12 may also have a pressure relief device 22 when the external pressure increases above the design pressure. Hydrogen is filled into the container 10 through a check valve 20 that allows only one-way flow, i.e., into the container 10. Hydrogen flows from the vessel 10 through the valve opening in response to power train demand.

From a safety perspective, hydrogen storage vessels have a limited life span. Once a sufficient number of filling cycles, and thus high strain, has been placed on the container 10, the container is no longer utilized. This system provides a means of monitoring the amount of strain and fatigue placed on the hydrogen storage vessel 10.

To monitor the useful life of the container 10, a sensor 40 is incorporated to monitor the number of fill cycles to the container 10. In an exemplary implementation, the sensor 40 is a strain gauge. Any type of meter or sensor 40 may be utilized to signal that a fill has been made.

In an exemplary embodiment of the invention, a sensor 40 is built into the container 10 wall or valve 12 to detect each time the container 10 is filled. The sensor 40 monitors the number of fill cycles until the number of fill cycles reaches a predetermined termination point. When the number of filling cycles has reached this predetermined end point, the shut-off device is activated.

In an exemplary embodiment, an influential event occurs whenever the vessel 10 is filled above 90% of the rated operating pressure or rated hydrogen quality. When this influential event occurs, the sensor 40 indicates that the fill cycle should be counted. It is also possible to count the number of partial fills at the completion of a fill event.

In a further embodiment, the controller 42 is utilized to count the number of cycles. Once the system has reached the predetermined termination point for the number of fill cycles, the controller 42 activates the cut-off device 46 to prevent the system from allowing any further fill cycles.

For example, a vehicle may have an expected utilization of approximately 250,000 miles. A typical on-board hydrogen storage vessel 10 has a range of about 200 miles. Thus, the container 10 may be designed for cycles of filling up to about 1250 cycles. In this example, 1250 may be the predetermined termination point for the number of cycles of the exemplary hydrogen storage system. After controller 42 has counted the number of cycles designed for the system, shut-off device 46 is activated. However, these numbers are merely illustrative. One skilled in the art can design another container utilizing the disclosed safety and closure device with a variety of ranges and design parameters.

In the implementation illustrated in fig. 3, the sensor 40 may be a metallic strain gauge 28. The metallic strain gauge 28 comprises very thin metal wires 36, or more commonly metal foils, arranged in a grid pattern 30. The grid pattern 30 maximizes the number of metal wires or foils 36 that are subjected to strain in parallel directions. The grid 30 is bonded to a thin backing or carrier 32. For example, the grid 30 may be bonded to the carrier 32 using solder tabs 34. The carrier 32 is mounted to the container 10 wall. When the container 10 is subjected to strain during a filling cycle, the strain is transferred directly to the strain gauge 28, thereby increasing the length of the grid 30. The metallic strain gauge 28 then responds by a linear change in resistance, thereby sensing the fill cycle.

In another implementation, the sensor 40 may be a fiber optic strain gauge 60. As illustrated in fig. 4, the fiber optic strain gauge 60 includes a fiber optic cable 62 embedded in the wall of the container 10. The fiber optic cable 62 includes a bragg grating 66 enclosed in a glass tube 62. The glass tube 62 is attached to the fiber optic cable 62 with an adhesive 68. The fiber bragg grating 66 is a periodic variation in refractive index along the length of the fiber. In the fiber optic strain gauge 60, the sensor 40 measures strain by shifting the light frequency of the light reflected off the fiber from the bragg grating 66, which is itself embedded within the fiber 62. Fiber optic cables are useful because the optical fibers are immune to electrical interference and corrosion.

Fig. 5 depicts another implementation showing the sensor 40 as an acoustic emission strain gauge. The acoustic emission strain gauge includes a transmitter 70 and a receiver 72 mounted to the container 10. The acoustic emission signal waves 74 may serve as a medium for detecting when a material change (e.g., strain on the container 10) occurs to the container 10. When the receiver 72 has received this acoustic emission signal wave 74, the system senses that a fill cycle has occurred.

In another embodiment of the invention, a flow switch or pressure drop switch is incorporated into or near the valve housing 24 to count the number of fill cycles. As shown in fig. 6, there is a pressure transducer 16 in the valve 12. The pressure transducer 16 monitors the pressure in the valve 12. When the valve 12 is under pressure, the pressure transducer 16 displaces and converts this displacement into an electrical output, such as a voltage or current. When the pressure transducer 16 emits a voltage, the system counts one fill cycle.

To monitor changes in pressure, a movable diaphragm is incorporated into the valve body housing 24. When the container is filled with hydrogen, the diaphragm contacts a switch that counts the number of fill cycles.

In another embodiment, a temperature changer 18 present in the system is used to monitor the number of fill cycles. The system 5 monitors when the temperature of the stored gas increases, which temperature increase is associated with the filling process. In another embodiment, the system 5 monitors and counts the number of temperature reductions of the stored gas associated with the emission process.

The safety system and the closing means 5 can be controlled by several different controllers. In one embodiment, the safety and shutdown system is attached to an engine control unit in a vehicle. The signal from the sensor 40 will be processed by the fuel system controller to record the total number of fills.

In another implementation, the sensor 40 or strain gauge may be interconnected to separate the microprocessor attached to the container 10. The microprocessor will count the number of fill cycles. Once the number of fills has reached the predetermined termination point, the microprocessor activates the shut-off device 46, thereby rendering the container unusable.

In other embodiments, the controller 42 may be a mechanical counter. The mechanical counter may comprise a switch that is activated wherever the fill cycle is completed. The mechanical counter may then deactivate the system and prevent further use of the hydrogen container 10.

In the exemplary embodiment, as the predetermined number of fill cycles has been reached, the controller 42 will activate the check valve 5 to prevent further filling of the storage system. Thus, the system will close the check valve and prevent more fuel from entering the system.

In another embodiment, the controller 42 will permanently shut off power to the solenoid valve 3 so that no more fuel is released. This will essentially deactivate the fuel system and ground the vehicle.

In another embodiment of the invention, the controller 42 will cause the pressure transducer 16 to send a false "full" signal to the fueling station and/or the vehicle on-board fueling control unit so that the container 10 is no longer filled due to the "full" indication.

In an exemplary embodiment, the closure system further includes a warning device 44 to notify the vehicle operator that the container 10 is approaching its predetermined termination point. The warning device 44 will indicate to the vehicle operator that service is required, or that the container may need to be replaced to continue operation of the vehicle.

In another implementation of the present invention, hardware and software measurements 48 are introduced to make the fill cycle and cut-off device 46 tamper-resistant in a manner similar to odometer tamper protection for today's vehicles. This prevents the vehicle user from overusing the system and continuing to use the hydrogen container 10 after the container 10 has achieved its full useful life.

Various embodiments of the present invention may be applicable to pressurized liquid hydrogen storage systems, in the form of compressed gases at generally room temperature, compressed gases at temperatures between room temperature and cryogenic temperatures, and gases stored by physical adsorption, or in the form of chemical hydrides.

While the apparatus and method have been described with respect to what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not necessarily limited to the disclosed embodiment. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures. The present invention includes any and all embodiments of the following claims.

Claims (25)

1. A safety warning and shutdown system for a hydrogen storage vessel, comprising:

a valve assembly attached to the container, the valve having a check valve, an electrical solenoid, a pressure transducer, and a temperature transducer for filling the hydrogen storage container;

a sensor for monitoring the number of fill cycles; and

a shut-off device for disabling further use of the hydrogen system after a predetermined limit on the number of fill cycles is reached.

2. The safety warning and shutdown system of claim 1, wherein the sensor is a strain gauge disposed in the fuel container.

3. The safety warning and shutdown system of claim 1, wherein the sensor comprises a strain gauge that measures strain in the container with an embedded fiber optic.

4. The safety warning and shutdown system of claim 1, wherein the sensor is a metal strain gauge that measures strain in the container.

5. The safety warning and shutdown system of claim 1, wherein the sensor measures strain using acoustic emissions.

6. The safety warning and shutdown system of claim 1, wherein the sensor is a strain gauge including a diaphragm in the valve that is activated when pressure in the valve changes.

7. The safety warning and shutdown system of claim 1, further comprising a warning system for notifying a vehicle user that the system is approaching a predetermined limit.

8. The safety warning and shutdown system of claim 1, further comprising software and hardware measurements to prevent tampering with the system once the system reaches the predetermined limit.

9. The safety warning and shutdown system of claim 1, wherein the fill cycles are counted each time the hydrogen container is filled above 90% of the rated pressure or mass.

10. The safety warning and shutdown system of claim 1, wherein the shutdown device is a controller that counts the number of fill cycles.

11. The safety warning and shutdown system of claim 1, wherein after the number of fill cycles has reached the predetermined limit, the shutdown device deactivates the electrical solenoid to disable the valve and prevent further use of the hydrogen system.

12. The safety warning and shutdown system of claim 1, wherein after the number of fill cycles has reached the predetermined limit, the shutdown device deactivates the check valve to disable the valve and prevent further use of the hydrogen system.

13. The safety warning and shutdown system of claim 1, wherein the shutdown device is a controller that counts a number of increases in temperature of the stored gas, the increases in temperature associated with a filling process.

14. The safety warning and shutdown system of claim 1, wherein the shutdown device is a controller that counts a number of times a temperature of the stored gas decreases, the temperature decrease associated with an exhaust process.

15. The safety warning and shutdown system of claim 1, wherein the system prevents further filling of the hydrogen storage system after the number of fill cycles has reached the predetermined limit by sending a glitch to a fueling station controller indicating that the system has been completely filled.

16. The safety warning and shutdown system of claim 1, wherein the controller is an engine control unit.

17. The safety warning and shutdown system of claim 1, wherein the controller is a separate microprocessor attached to the gas tank.

18. A method of providing a safety warning and shutdown system for a hydrogen storage vessel, the method comprising:

providing a hydrogen storage container, a valve assembly attached to the container, the valve having a check valve for filling the hydrogen storage container, an electrical solenoid, a pressure transducer, and a temperature transducer;

counting the number of fill cycles with a sensor; and

disabling the valve and further use of the hydrogen system after a predetermined number of fill cycles is reached.

19. The method of claim 18, wherein the sensor comprises a strain gauge that measures strain in the container using an embedded fiber optic.

20. The method of claim 18, wherein the sensor is a metal strain gauge that measures strain in the container.

21. The method of claim 18, wherein strain is measured using an acoustic emission monitoring system.

22. The method of claim 18, wherein the sensor is a pressure transducer located in the valve of the system.

23. The method of claim 18, further comprising alerting a vehicle user that the system is approaching the predetermined number of fill cycles.

24. The method of claim 18, further comprising preventing tampering with software and hardware measurements within the system once the system has reached the predetermined number of fill cycles.

25. The method of claim 18, further comprising deactivating the check valve to disable the valve and prevent further use of the hydrogen system after the number of fill cycles has reached the predetermined number.