Patent Application
20090103838
The present disclosure relates generally to a fluid storage tank, and more particularly, to a collapsible fluid storage tank.
Engine exhaust emissions are becoming increasingly scrutinized by engine manufacturers. Internal combustion engines, including diesel engines, gasoline engines, gaseous fuel-powered engines, and other engines known in the art, exhaust a complex mixture of air pollutants. The air pollutants are composed of gaseous and solid compounds, including particulate matter, nitrogen oxides (NOx), and sulfur compounds. One method that has been implemented by engine manufacturers to comply with the regulation of NOx exhausted to the environment has been to implement a strategy known as selective catalytic reduction (SCR).
An SCR system works by releasing a reducing agent, such as ammonia, into the engine exhaust flow in the presence of a catalyst. The reducing agent reacts with the NOx in the exhaust flow, on the surface coating of the catalyst, to create environmentally friendly products, such as nitrogen gas and water. In practice, ammonia is rarely used because it is toxic and difficult to handle. Urea, relatively easy to handle, can be converted to ammonia while heated and, thus, becomes a more popular choice of reducing agent for engine manufacturers. Urea is typically contained in a storage tank onboard an associated vehicle and pre-heated and fed to the exhaust gases on-demand via an injector or a pump.
To comply with increasingly stringent emissions standards for vehicles enforced by governments and regulatory agencies, manufacturers are required to include additional components that operate to reduce the emitted exhaust gas. Fluid tanks such as, for example, urea tanks in the SCR system, usually take up considerable space in the machine otherwise reserved for the additional components. Therefore, it is desirable to develop new storage technologies to make space available for these additional components in a typical vehicle.
Rigid tanks for storing urea, for example, steel tanks, usually have defined shapes and fixed sizes. Such tanks do not make the most efficient use of space. In particular, rigid tanks take up the same size of space even when the stored urea is mostly consumed. It is therefore desirable to use collapsible storage tanks with variable shapes, so that space is more efficiently utilized and additional components could be included without increasing the size of the vehicle.
Incorporating additional components into a typical vehicle, to comply with the stringent emissions standards, imposes additional challenges on machine accessibility. For example, it becomes difficult to secure some space for assembly and service access of the vehicle. Therefore, collapsibility, beyond flexibility, of the storage tank is desirable so that additional space may be generated by depletion of the stored fluid.
Furthermore, for the purpose of urea storage, flexibility in the storage tank is important for the additional reason that urea may easily crystallize and vaporize. For example, the crystallization point of urea is −11° C. Therefore urea may crystallize under extremely cold climatic conditions. Crystallization of the urea may generate expansion forces large enough to damage a rigid tank. In the other extreme, high temperature may cause the urea to vaporize. High vapour pressure generated within a rigid tank could also cause damage to the tank.
In addition, for the purpose of urea storage, efficient heat dissipation is desirable. Urea is pre-heated to generate ammonia before it is injected onto the exhaust gas flow. High temperature may occur near an associated heating element and/or the urea storage tank. Therefore, in order to avoid localized over-heating, it is important to include a heat sink that absorbs redundant heat.
One urea storage container is described in published U.S. Application No. 2002/0081239 to Palesch et al. (“the '239 publication”). The '239 publication describes a storage container containing a urea solution used for exhaust gas after treatment. The storage container includes walls at least partially formed by a flexible pressure membrane. The storage container described in the '239 publication is configured to be placed inside a pressure chamber, into which compressed air is supplied. The external pressure generated by the compressed air deforms the flexible pressure membrane. Therefore the urea flows into a urea conveying conduit by pressure loading.
Although the urea storage container described in the '239 publication may be effective for storing and supplying urea, it may be problematic. For example, the container described in the '239 publication offers only minimal flexibility in varying its size and shape, and it still occupies nearly the same amount of space even when the stored urea is mostly consumed. As a result, it does not effectively make space to fit in additional components required by stringent emissions standards.
Furthermore, the container described in the '239 publication may provide insufficient accessibility for assembly and service of an associated vehicle. For similar reasons as described above, the container described in the '239 publication can not collapse even after the stored urea is depleted and, therefore, the container may be unable to generate space for service personnel to access the machine.
In addition, the solution provided by the '239 publication may lack reliability when used for storing urea. For example, the urea storage container is placed in a pressure chamber and, thus, the flexible wall can deform only inward away from the pressure chamber. However, expansion generated by crystallization or vaporization of the stored urea applies outward forces on walls of the chamber. As a result, the container and chamber described in the '239 publication may be incapable of absorbing the generated expansions.
Finally, the container described in the '239 publication may be inefficient in heat dissipation. For example, no heat dissipation device is provided to absorb redundant heat associated with a urea heater placed inside the pressure chamber. Therefore, the container described in the '239 publication may experience over-heating and bear an excessively high temperature.
The present disclosure is directed at overcoming one or more of the problems set forth above.
In one aspect, the present disclosure is directed to a fluid storage tank. The fluid storage tank may include a bladder configured to store fluids, occupy a variable space, and collapse as the stored fluid is depleted. The fluid storage tank may also include at least one connecting component configured to connect the bladder to a machine.
In another aspect, the present disclosure is directed to a method of storing fluids. The method may include connecting the bladder to a machine. The method may also include storing fluids in a bladder and varying the size of the bladder. The method may further include collapsing the bladder as the stored fluid is depleted.
In yet another aspect, the present disclosure is directed to a method of gaining service access to a machine. The method may include manually depleting fluid stored in a bladder. The method may also include collapsing the bladder as the stored fluid is depleted and creating space in the machine.
Collapsible fluid tank 200 may include a collapsible bladder for storing fluid. The stored fluid may be any type of fluid used by the machine and/or power source 101, such as, for example, urea, fuel, engine oil, transmission oil, coolant, and brake fluid. Fluid storage tank 200 may further include one or more connecting components to seal the bladder and connect it with an engine compartment or other components in the engine compartment. Fluid storage tank 200 may have a variable size and a variable shape. When filled with fluid, fluid storage tank 200 may flex around rigid components such as power source 101, battery 102, and power-conversion unit 103, and efficiently occupy small spaces among these rigid components. When the stored fluid is depleted, fluid storage tank 200 may collapse and occupy only minimal space. As fluid storage tank 200 collapses, spaces around power source 101, battery 102, and power-conversion unit 103 may become available for assembly and service access. Fluid storage tank 200 will be illustrated and described in greater details with regard to
Collapsible bladder 201 may be fabricated from any suitable fluid-impervious elastomeric material, such as, for example, fiber-reinforced membrane and rubber membrane. The size of collapsible bladder 201 may vary due to the distending and contracting of the elastomeric wall. Collapsible bladder 201 may be mounted or connected to other components of a mobile machine via connecting components 202. For example, consistent with one disclosed embodiment, connecting component 202 may be a bulkhead or rigid panel that seals the bladder and connects the bladder to a wall of engine compartment 100. The bulkhead may include one or more holes and connectors that connect the bladder with fluid passages. Connecting component 202 may also be a non-rigid component such as, for example, a pin that sticks through collapsible bladder 201 and mounts it to engine compartment 100.
Fluid may be pumped into collapsible bladder 201 by a pump 204 via inlet 205. One terminal of inlet 205 may be connected to collapsible bladder 201 via connecting component 202. A fluid depletion valve 206 may be installed at an opposing terminal of inlet 205. Fluid depletion valve 206 may be turned on to allow fluid flow into or out of inlet 205. While turned off, fluid depletion valve 206 may act as a closure of inlet 205 to prevent the effusion of the stored fluid. One terminal of inlet 205 may be manufactured to have threads, for easy connection of an external fluid pipe 207, which may connect an external or off-board fluid container 208.
Stored fluid may flow out of collapsible bladder 201 to other parts of the exhaust treatment system through outlet 203. One terminal of outlet 203 may be connected to collapsible bladder 201 via connecting component 202. The opposing terminal of outlet 203 may be connected to a fluid consumer (not shown), such as a urea or fuel injector, or a hydraulic pump.
Bladder 201 may include one or more compartments for storing different types of fluid. Consistent with one disclosed embodiment,
Consistent with another disclosed embodiment,
In one example, inner compartment 401 may store urea. Urea may be injected into the engine exhaust flow, and be used as a reducing agent in the selective catalytic reduction (SCR) process. Urea may be pre-heated by a heating element 405 before it flows out via outlet 404 and injected onto the exhaust gas flow. Heating element 405, for example, a heating pipe, may be placed near the urea storage compartment 401. Outer compartment 402 may store a relatively large volume of fuel or coolant and absorb redundant heat generated by heating element 405. Therefore, outer compartment 402 may serve as a heat sink, and may effectively avoid localized over-heating at inner compartment 401.
The disclosed collapsible fluid storage tank may be utilized to store any type of fluid such as, for example, urea, fuel, coolant, engine oil, transmission oil or hydraulic fluid. According to one embodiment of the present application, different types of fluid may be stored in the several compartments of a collapsible fluid storage tank.
With the incorporation of a collapsible bladder 201, more efficient usage of space may become possible. For example, collapsible bladder 201, made from elastomeric material, may change its shape and fill in the space around connecting components located within the engine compartment 100. Therefore, additional components required by stringent emissions standards may be accommodated in a typical machine.
Furthermore, the incorporation of a collapsible bladder may gain accessibility to the machine. For example, the fluid stored in collapsible storage tank 200 may be manually depleted via inlet 205, and collapsible bladder 201 may collapse to occupy a minimal space. As a result, service personnel may gain access for assembly and service of the machine.
In addition, elastomeric characteristic of the bladder wall may absorb the expansions generated by crystallization and vaporization of the stored fluid, for example, urea. Therefore, the present application may minimize the potential damage of the storage tank due to expansions.
Finally, the collapsible bladder may store several different types of fluid and use one fluid as the heat sink for another. For example, a collapsible bladder may store fuel or coolant in one compartment and urea in another proximal (adjacent or surrounding) compartment. Therefore, the redundant heat generated during the urea heating process may be absorbed by the fuel or coolant compartment.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed fluid storage tank without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed fluid storage tank. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
