Patent Application
20080289320
This invention relates to internal combustion engines, including but not limited to substance dispensers for procuring and dispensing substances used to treat exhaust gas generated by an internal combustion engine.
Internal combustion engines generate exhaust gases during operation. These exhaust gases are typically treated and purified using various known methods. One known method of treating engine exhaust gas is by use of additives or chemical compounds that are introduced into an exhaust gas stream, downstream of an engine and upstream of an exhaust gas treating device, such as an oxidation catalyst or a particulate filter. One known chemical substance that may be used to activate the oxidation catalyst, or to lower the regeneration temperature of a particulate filter, is a solution of urea, water, and monohydric or polyhydric alcohol.
In a vehicle having a urea solution dispensing device, a separate tank containing the urea solution is installed onto the vehicle. A dispenser meters a required amount of the urea solution to be dispensed based on an operating condition of the engine in the vehicle, and an injector device injects the required amount of urea into an exhaust pipe of the vehicle at a location upstream of a treatment device. The amount of urea contained in the tank is finite and less than a total amount that the vehicle will require through the vehicle's service life. This necessitates a periodic replenishment of the urea solution in the tank.
One known method of replenishing a urea solution supply for a vehicle, for example, can be found in U.S. Pat. No. 6,263,924, issued on Jul. 24, 2001 to Grosser (the '924 patent). The '924 patent describes a dispensing system for a fuel additive that is mixed with the fuel while the fuel is added to a vehicle's fuel tank. Another example of a dispenser for an additive that is mixed with the fuel, or injected into an exhaust stream of a vehicle can be found in U.S. Pat. No. 7,150,145, issued on Dec. 19, 2006 to Patchett et al. (the '145 patent). The '145 patent describes an SCR system for a vehicle which uses an external reducing reagent to convert NOx emissions in a manner which accounts for transient emissions that is correlated to the storage capacity of the reducing agent.
Both of the aforementioned systems, and all such systems in general, depend on the availability of a urea solution to a vehicle operator when replenishment is necessary. Currently, an infrastructure for urea availability is unavailable, or available to a very limited extent.
A reservoir for storing an additive solution includes a reservoir volume formed internally to the reservoir. The reservoir volume is arranged to sealably store the additive solution. An inlet passage is in fluid communication with the reservoir volume. A canister is disposed on the reservoir. The canister includes a cup portion that forms an internal volume having a permeable portion, and a head portion connected to the cup portion. A plurality of pellets is disposed in the internal volume of the cup portion of the canister, such that a fluid contained in the reservoir volume is in fluid communication with the plurality of pellets through the permeable portion of the canister. Dissolution of the pellets in the fluid advantageously yields the additive solution.
The following describes an apparatus for and method of providing an easily replenishable supply of an additive for use with exhaust gas after-treatment components on a vehicle with an internal combustion engine. A block diagram of a system for storing and dispensing an additive for treating exhaust gas in a vehicle 100 is shown in
At times when the engine 102 operates, fuel from the fuel supply passage 106 is mixed with air from the air inlet passage 104 in a plurality of cylinders (not shown) for combustion. The combustion of the fuel and air mixture yields power that is mechanically transferred to the vehicle. Exhaust gas generated by the combustion in the cylinders is collected and expelled from the engine 102 through an exhaust pipe 114. The open-headed arrows in
The exhaust pipe 114 contains devices that treat and clean constituents of the exhaust gas emitted by the engine 102 during operation. These devices may include a pre-catalyst 116, a catalyst 118, a filter (not shown), a muffler (not shown), and so forth. These devices 116 and 118 may catalyze the exhaust gas to remove various compounds, such as hydrocarbons, nitrous and nitric oxides, and so forth, as is known. An effectiveness and efficiency of operation of devices that treat exhaust gas may be augmented by use of additives, such as chemical solutions containing urea and other chemicals, as is also known.
The vehicle 100 advantageously has an easily replenishable supply device that injects an additive compound into the exhaust pipe 114. As part of the additive supply device, the vehicle 100 includes a tank or reservoir 120 connected thereto. The reservoir 120 has an inlet opening or neck 122 that can be sealed with a cap (not shown) and is easily accessible to an operator. For example, the neck 122 may be located adjacent to a fuel fill port of the vehicle. The tank 120 includes a de-ionization filter 124 disposed in line with the neck 122 that is arranged to de-ionize and filter a liquid, such as water, that fills the tank 120 through the neck 122.
A doser device 134 is disposed on the tank 120 and is in fluid communication with an interior volume 128, and a conduit 136 that connects the doser device 134 with an additive nozzle 138 that is disposed in the exhaust pipe 114 between the pre-catalyst 116 and the catalyst 118.
The doser device 134 is advantageously capable of admitting a controlled and determinable quantity of fluid from the interior volume 128, and then pumping the fluid through the conduit 136 to be injected into the exhaust pipe 114 through the additive nozzle 138. The tank 120 also includes an additive canister 140 and an additive concentration sensor 142 disposed therein. A control module 144 is operably associated with various components, as denoted by double-headed-dashed-line arrows. An engine communication channel 146 connects the module 144 with various engine components, for example, exhaust gas temperature and/or pressure sensors, and so forth. A doser communication channel 148 connects the module 144 with the doser 134. An additive quality sensor communication channel 150 connects the module 144 with the additive concentration sensor 142, and so forth. Other components, such as a temperature sensor, heater, and so forth, may be associated with the tank 120.
During operation, the concentration sensor 142 senses a concentration of the additive solution in the tank 120, a solution that is created through dilution of additive from the additive canister 140 into water present in the tank 120, and relays the concentration measured to the control module 144 through the additive quality sensor communication channel 150. The control module 144 uses the concentration information of the solution in the tank 120, along with engine operating parameters that are received by the control module 144 through the engine communication channel, and at appropriate times initiates a solution injection into the exhaust pipe 114.
When an injection event is initiated, certain parameters are pertinent to proper operation of the system. One such parameter is the desired amount of additive that the control module 144 determines is required for the injection event. The control module 144 determines a proper amount of solution to be passed to the injector 138 based on a concentration of the solution in the tank 120 that will yield a desired net amount of additive. Once the appropriate determination has been made, the control module 144 sends a command to the doser device 134 to pump to the injector 138 an appropriate amount or volume of solution. The doser device 134 pumps the appropriate amount of solution to the injector 138, which in turn injects same into the exhaust pipe 114. This cycle may repeat as necessary, until a time when the solution in the tank 120 begins to deplete. At that time, a replenishment of the solution in the tank 120 becomes necessary.
When replenishing the solution in the tank 120, an operator simply and advantageously adds water into the tank 120 through the neck 122. In contrast to known methods of replenishing a solution of urea into a tank of a vehicle, in accordance with this embodiment, the operator may add a solution of urea, if such a solution is available, or may alternatively simply add water. The water added into the tank 120 to fill the tank 120 comes in contact with the additive canister 140.
A partial cross section view of one embodiment for a canister 200 in accordance with the invention is shown in
The permeable portion 208 includes a plurality of openings 214 that are formed in and through the material of the cup portion 202. In the embodiment shown the openings 214 are elongates slots, but any other type and shape of opening will be effective, for example, holes, or a grid, and so forth. The openings 214 are large enough to allow for water to pass into and out of the permeable portion 208 when the canister 200 is immersed in water. The openings 214 are advantageously small enough not to allow any of the pellets 212 to fall out of the canister 200 when the pellets are large enough to block any of the passages in the doser 134, the conduit 136, or the injector 138, seen in
An alternate embodiment of a canister 300, shown in partial cross-section as installed onto a wall 302 of a tank 304, is shown in
A flowchart for a method of providing an additive to a device disposed within an exhaust stream for exhaust gases containing combustion byproducts is shown in
An additive solution is stored in a storage reservoir in step 402. The additive solution is an aqueous solution of urea that is yielded when solid urea-containing pellets, palletized with a binder material and contained in a canister connected to the storage reservoir, are exposed to water added to the reservoir. The binder material that binds the pellets is advantageously capable of providing an aqueous solution of urea that saturates within a relatively narrow range of percent (%) concentrations of urea, independently of a temperature of the water, the reservoir, or ambient temperature. At times when an engine operates and a control module decides that at least one after-treatment component requires regeneration, the control module decides to dispense a desired amount of additive into a gas stream at step 404.
In conducting the decision to dispense the desired amount of additive into a gas stream of step 404, the control module first senses or calculates a concentration of additive in the additive solution at step 406. The sensing or calculation of additive concentration in the additive solution may be accomplished by a modeling calculation that is based on the original amount of solvent added to the reservoir, or the amount of solution historically dispensed from the last replenishment thereof, or more directly, by use of a concentration sensor disposed in the reservoir that operably communicates with the control module. In a preferred embodiment, a concentration sensor is used to sense the concentration of additive in the additive solution in the reservoir. The concentration sensor yields a concentration reading, which is communicated to the control module. The concentration reading is used by the control module to calculate a desired volume of solution to be dispensed to yield the desired amount of additive, based on concentration. Use of the concentration sensor may also advantageously be made to determine, at step 408, whether the additive solution contained in the reservoir has a concentration that is within an acceptable range, for example, a range between 1 and 4 percent.
At times when the concentration of additive in the additive solution is deemed to be outside of the acceptable range, for example, if the concentration is below 1% or above 4% by weight, then a negative decision from the determination step 408 will cause the control module to provide a notification to an operator of the vehicle that replenishment of additive solution is required at step 410. This notification may be conducted by any mode known, for example, an illumination of an indicator lamp on a dashboard of the vehicle, an appropriate message to a vehicle's message display, and so forth.
At times when replenishment of the additive solution is required, an operator refills or replenishes the solvent, or water, in the storage reservoir, and some of the times, the operator might also replace an additive canister containing additive in solid form, at step 412.
At times when the determination is made in the decision step 408 that the concentration of the additive in the additive solution is acceptable, a desired volume of additive solution to be injected that will yield the desired amount of additive based on the concentration of the additive in the additive solution is calculated in the control module at step 414. The calculation of step 414 may fundamentally be the ratio between the desired amount or mass of additive, divided by the density of the additive in the additive solution, to yield a volume of additive solution that contains the desired amount of additive.
After the desired volume of additive solution has been determined, the control module may instruct a doser to dispense the desired amount of additive solution from the reservoir, and inject the desired amount of the additive solution into a passage leading to an injector that will finally dispose of the solution in the exhaust gas stream, at step 416. The doser may be an electronically controlled fluid pump capable of dispensing known volumes of fluids. The doser, for example may be a reciprocating piston pump driven by a step motor that is able to dispense incrementally known volumes of fluid with each action of the piston. Alternatively, the doser may be a vane pump that has a fluid flow-meter operably associated therewith that is able to measure a volume of fluid being pumped therethrough.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
