Patent Application
20220235694
The present description relates to a method and systems for reducing heat loss to a turbocharger during cold engine starting. The method and systems may improve delivery of heat to a catalyst during an engine cold start.
An internal combustion engine of a vehicle may emit higher levels of emissions during cold engine starting. A catalyst that is coupled to the engine may not be prepared to process the engine emissions for a period of time after the engine is started. Therefore, higher levels of engine emissions may reach the atmosphere than may be desired.
One way to reduce engine emissions is to raise a temperature of the catalyst to above catalyst light-off temperature (e.g., a temperature at which the catalyst may operate above a threshold efficiency level) sooner. However, many engines include a turbocharger to increase engine output power and reduce engine fuel consumption. The turbochargers include a turbine that may be positioned in the engine's exhaust system upstream of the catalyst. The turbine may operate as a heat sink when an engine is started so that a temperature of exhaust gases that enter the catalyst may be reduced until the turbine and turbocharger reach higher temperatures. As a result, the catalyst may not reach its light-off temperature as soon as may be desired. Consequently, engine emissions may pass by the catalyst without being treated.
The inventors herein have recognized the above-mentioned issues and have developed an engine system, comprising: a catalyst including a plurality of flow chambers; a turbine pipe outlet arranged at about 45 degrees relative to a centerline of the catalyst; a turbine bypass passage pipe outlet arranged at about 45 degrees relative to the centerline of the catalyst; a three-way valve configured to distribute exhaust gas to the turbine bypass passage pipe outlet and the turbine pipe outlet; and an actuator to adjust a position of the three-way valve.
By orienting a turbine pipe and a turbine bypass passage pipe at about 45 degrees from a centerline of a catalyst, it may be possible to provide the technical result of reducing heat lost to a turbocharger turbine so that a catalyst may reach its light-off temperature sooner, thereby reducing engine emissions levels. In particular, the 45 degree angle may facilitate use of a three-way valve to control exhaust flow through the turbine bypass passage pipe and the turbine pipe so that heat loss to the turbocharger turbine may be significantly reduced. In addition, the angular arrangement between the turbine bypass passage pipe and the centerline of the catalyst and the angular arrangement between the turbine pipe and the centerline of the catalyst may improve catalyst brick utilization during an engine cold start so that engine emissions may be reduced.
The present description may provide several advantages. In particular, the approach may reduce engine tailpipe emissions. Further, the approach may reduce system cost via utilization of a single turbine bypass actuator. In addition, the approach may reduce flow passage length so that more exhaust gas heat may be conserved until the exhaust gases reach the catalyst, thereby reducing an amount of time to reach catalyst light-off temperature.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
The advantages described herein will be more fully understood by reading an example of an embodiment, referred to herein as the Detailed Description, when taken alone or with reference to the drawings, where:
The present description is related to reducing exhaust heat that may be lost heating a turbocharger turbine during an engine cold start. The exhaust heat may be conserved via a turbocharger bypass pipe and turbocharger turbine pipe that are strategically arranged such that both the turbocharger bypass pipe and turbocharger turbine pipe may direct exhaust gas at substantially an entire face of a catalyst. The exhaust system may be part of a turbocharged engine as shown in
Referring to
Engine 10 is comprised of cylinder head 35 and block 33, which include combustion chamber 30 and cylinder walls 32. Piston 36 is positioned therein and reciprocates via a connection to crankshaft 40. Flywheel 97 and ring gear 99 are coupled to crankshaft 40. Optional starter 96 (e.g., low voltage (operated with less than 30 volts) electric machine) includes pinion shaft 98 and pinion gear 95. Pinion shaft 98 may selectively advance pinion gear 95 to engage ring gear 99. Optional starter 96 may be directly mounted to the front of the engine or the rear of the engine. In some examples, starter 96 may selectively supply power to crankshaft 40 via a belt or chain. In addition, starter 96 is in a base state when not engaged to the engine crankshaft 40 and flywheel ring gear 99.
Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53. The position of intake cam 51 may be determined by intake cam sensor 55. The position of exhaust cam 53 may be determined by exhaust cam sensor 57. Intake valve 52 may be selectively activated and deactivated by valve activation device 59. Exhaust valve 54 may be selectively activated and deactivated by valve activation device 58. Valve activation devices 58 and 59 may be electro-mechanical devices.
Direct fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, which is known to those skilled in the art as direct injection. Port fuel injector 67 is shown positioned to inject fuel into the intake port of cylinder 30, which is known to those skilled in the art as port injection. Fuel injectors 66 and 67 deliver liquid fuel in proportion to pulse widths provided by controller 12. Fuel is delivered to fuel injectors 66 and 67 by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown).
In addition, intake manifold 44 is shown communicating with turbocharger compressor 162 and engine air intake 42. In other examples, compressor 162 may be a supercharger compressor. Shaft 161 mechanically couples turbocharger turbine 164 to turbocharger compressor 162. Optional electronic throttle 62 adjusts a position of throttle plate 64 to control air flow from compressor 162 to intake manifold 44. Pressure in boost chamber 45 may be referred to a throttle inlet pressure since the inlet of throttle 62 is within boost chamber 45. The throttle outlet is in intake manifold 44. In some examples, throttle 62 and throttle plate 64 may be positioned between intake valve 52 and intake manifold 44 such that throttle 62 is a port throttle. Compressor recirculation valve 47 may be selectively adjusted to a plurality of positions between fully open and fully closed. Waste gate 163 may be adjusted via controller 12 to allow exhaust gases to selectively bypass turbine 164 to control the speed of compressor 162. Air filter 43 cleans air entering engine air intake 42.
Ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Exhaust system 109 may include a universal Exhaust Gas Oxygen (UEGO) sensor 126, which is shown coupled to exhaust manifold 48 upstream of three-way catalyst 70. Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 126.
Catalyst 70 may include multiple bricks and a three-way catalyst coating, in one example. In another example, multiple emission control devices, each with multiple bricks, can be used.
Controller 12 is shown in
Controller 12 may also receive input from human/machine interface 11. A request to start or stop the engine or vehicle may be generated via a human and input to the human/machine interface 11. The human/machine interface 11 may be a touch screen display, pushbutton, key switch or other known device.
During operation, each cylinder within engine 10 typically undergoes a four stroke cycle: the cycle includes the intake stroke, compression stroke, expansion stroke, and exhaust stroke. During the intake stroke, generally, the exhaust valve 54 closes and intake valve 52 opens. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder so as to increase the volume within combustion chamber 30. The position at which piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g. when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC).
During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head so as to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g. when combustion chamber 30 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means such as spark plug 92, resulting in combustion.
During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston movement into a rotational power of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48 and the piston returns to TDC. Note that the above is shown merely as an example, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.
Line 250 indicates a centerline of catalyst substrate 204. The centerline 250 runs parallel with the longitudinal direction of cells 208. Cells 208 may support a wash coating (not shown) comprising platinum, palladium, or other metals. Cells 208 direct the exhaust flow through substrate 204. Catalyst housing 202 supports substrate 204.
Turbocharger turbine bypass pipe 210 includes an outlet 210a and an inlet 210b. A centerline 251 of outlet 210a of turbocharger turbine bypass pipe 210 is oriented at about a 45 degree angle 255 (e.g., the angle between the centerline 251 of the turbocharger turbine bypass pipe outlet 210a and the center line 250 of the catalyst substrate 204 may be in a range from 35 degrees to 55 degrees) relative to centerline 250 of catalyst substrate 204. By placing outlet 210a at a 45 degree angle 255 relative to centerline 250, exhaust gases that flow through outlet 210a may be directed across the entire front face 205 of catalyst substrate 204. In addition, the entirety of exhaust gases passing through turbocharger turbine bypass pipe 210 may be directed to front face 205 of catalyst substrate 204. Further, flow utilization may be improved via the angled inlet and exhaust gases flowing through the turbocharger turbine bypass pipe 210 may sweep the entire substrate front face or surface 205.
Turbocharger turbine pipe 212 includes an outlet 212a and an inlet 212b. A centerline 252 of outlet 212a of turbocharger turbine pipe 212 is oriented at about 45 degree angle 256 (e.g., the angle between the centerline 252 of turbocharger turbine pipe outlet 212a and the center line 250 of the catalyst substrate 204 may be in a range from 35 degrees to 55 degrees) from centerline 250 of catalyst substrate 204. By placing outlet 212a at a 45 degree angle 256 relative to centerline 250, exhaust gases that flow through outlet 212a may be directed across the entire front face 205 of catalyst substrate 204. In addition, the entirety of exhaust gases passing through turbocharger turbine pipe 212 may be directed to front face 205 of catalyst substrate 204. Further, flow utilization may be improved via the angled inlet and exhaust gases flowing through the turbocharger turbine pipe 212 may sweep the entire substrate front face or surface 205.
In this example, waste gate 163 is a three way valve that is positioned at and between turbocharger turbine bypass pipe inlet 210b and turbocharger turbine pipe inlet 212b. In a first position, waste gate 163 may fully close off exhaust flow through turbocharger turbine bypass pipe 210. In a second position, waste gate 163 may fully close off exhaust flow through turbocharger turbine pipe 212. Waste gate 163 may also be adjusted to intermediate positions between the first position and the second position so that exhaust may flow through both the turbocharger turbine pipe 212 and turbocharger turbine bypass pipe 210. Actuator 260 may adjust the position of waste gate 163. Actuator 260 may be pneumatic or electrically operated.
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At 1302, method 1300 determines vehicle operating conditions. In one example, method 1300 determines engine temperature, ambient air temperature, amount of time since a most recent engine start, driver demand torque, engine speed, and engine load from the various sensors described herein. Method 1300 proceeds to 1304 after determining vehicle operating conditions.
At 1304, method 1300 judges if the engine is presently undergoing a cold engine start. A cold engine start may occur when engine temperature is less than a threshold temperature, the engine is being cranked or is at idle, the engine has been running (e.g., combusting fuel) for less than a threshold amount of time. If method 1300 judges that the engine is presently undergoing a cold engine start, the answer is yes and method 1300 proceeds to 1306. Otherwise, the answer is no and method 1300 proceeds to 1310.
At 1306, method 1300 adjusts a waste gate to a first position to fully close off exhaust flow to a turbocharger turbine. In one example, the waste gate may be the waste gate that is shown in
At 1308, method 1300 judges if the catalyst's temperature is above the catalyst's light-off temperature. If so, the answer is yes and method 1300 proceeds to 1310. Otherwise, the answer is no and method 1300 returns to 1308.
At 1310, method 1300 adjusts a position of the waste gate to a position that is based on a desired boost amount. The desired boost amount may be a function of engine speed and driver demand torque. In one example, the waste gate may be adjusted to a second position at which the waste gate fully closes off exhaust flow to the turbocharger turbine bypass pipe 210. By fully closing off exhaust flow to the turbocharger bypass pipe 210, full boost pressure may be provided to the engine. Alternatively, the waste gate may be adjusted to a third position that allows exhaust to flow through the turbocharger turbine bypass pipe 210 and through the turbocharger turbine pipe 212. The third position may be useful for part load conditions. Method 1300 proceeds to exit.
In this way, it may be possible to reduce heat loss to a turbocharger turbine during cold engine starting conditions. If the engine is warm, the waste gate position may be adjusted to improve engine efficiency. The waste gate may be constructed as a three-way valve as shown herein.
Thus, the method of
Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, at least a portion of the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the control system. The control actions may also transform the operating state of one or more sensors or actuators in the physical world when the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with one or more controllers.
This concludes the description. The reading of it by those skilled in the art would bring to mind many alterations and modifications without departing from the spirit and the scope of the description. For example, single cylinder, I3, I4, I5, V6, V8, V10, and V12 engines operating in natural gas, gasoline, diesel, or alternative fuel configurations could use the present description to advantage.
