Method and system for controlling exhaust gas recirculation due to environmental conditions

Abstract

Procedure, with the step: Controlling an exhaust gas flow passing through an exhaust gas recirculation system of an engine system, based on a throttling level of a turbocharger, further with the step of reducing the exhaust gas flow in response to an environmental condition.

Description

AREA

[0001] Exemplary embodiments of the invention described here relate to the operation of an exhaust gas recirculation system of an engine system. BACKGROUND

[0002] Under ambient conditions that increase an engine's operating temperature, engine power may decrease, resulting in reduced engine efficiency. Some vehicles, such as rail vehicles, may be subjected to tunnel operating conditions, where the vehicle traverses a confined space, such as a tunnel. During operation in a tunnel, the temperatures of various vehicle systems, such as the engine and cooling systems, can rise. In some embodiments, these temperatures can increase considerably, leading to reduced power and overheating of the rail vehicle's engine.

[0003] One approach involves reducing heat dissipation to the cooling system and the tunnel in response to a tunnel operation notification by adjusting an operating parameter, such as the engine exhaust gas recirculation (EGR). For example, the amount of exhaust gas recirculation from the engine can be significantly or completely reduced. However, in such an approach, the operation of a turbocharger in the engine may exceed a throttling level, resulting in a reduction in turbocharger efficiency.

[0004] US 2015 / 0089940A1 discloses a method for controlling an engine, comprising the following steps: In response to a transient operational event, a first exhaust gas recirculation (EGR) quantity is determined which, if supplied to an engine intake, would prevent the turbocharger compressor from surging in a turbocharger; a second EGR quantity is determined which, if supplied to the intake, would prevent the turbocharger compressor from throttling in the turbocharger; and a third EGR quantity is determined which, if supplied to the intake, would prevent engine smoking. The EGR supplied to the engine intake is adjusted according to the determined first, second, and third quantities.

[0005] Independent claims 1 and 9 define the invention in different respects. Dependent claims 2 to 8 describe embodiments of the invention. SHORT DESCRIPTION

[0006] In one embodiment, a method (e.g., a method for controlling an engine) includes controlling an exhaust gas flow through an exhaust gas recirculation system based on a throttling level of a turbocharger.

[0007] The process may also include the step of reducing the exhaust gas flow in response to an environmental condition.

[0008] The ambient conditions may include an ambient temperature that is above a threshold temperature.

[0009] The engine system can be located on board a vehicle, with the environmental condition involving the operation of the vehicle moving through a space with restricted airflow.

[0010] Regulating the flow or exhaust gas may involve reducing the exhaust gas flow to a first level, where the first level is based on the throttling level.

[0011] The first level can also be based on a pressure ratio across a compressor of the turbocharger and on a rotational speed of the turbocharger.

[0012] Each of the above-mentioned methods may also include the step of further reducing the exhaust gas flow in response to the overheating of a component and a resulting reduction in engine power, based on a wider tolerance range than the throttling level, the wider tolerance range being based on the resulting reduction in engine power.

[0013] The overheating of the component can include an oil temperature, a coolant temperature and / or an exhaust gas temperature above a corresponding threshold temperature.

[0014] Further reduction may involve decreasing the exhaust flow to a second level, with the second level increasing the mass airflow through the turbocharger within a threshold range of a set throttling level.

[0015] In each of the above-mentioned methods, regulating the exhaust gas flow may involve adjusting one or more valves in the exhaust gas recirculation system.

[0016] In this way, turbocharger operation can be maintained below a throttling level, thereby increasing turbocharger efficiency and reducing turbocharger wear caused by exceeding the turbocharger's speed limit. In some embodiments, the control of the exhaust gas flow through the exhaust gas recirculation system can be implemented in response to an ambient condition. For example, the exhaust gas recirculation flow can be reduced during an ambient condition, such as when the ambient temperature exceeds a threshold temperature, and / or during operation with restricted airflow, thereby reducing the load on the engine's cooling system and improving engine efficiency.

[0017] It is understood that the above summary is suitable for introducing, in simplified form, a selection of concepts that are described in more detail in the detailed description. It is not intended to define important or essential features of the present invention, the scope of which is defined exclusively by the claims appended to the detailed description. Furthermore, the present invention is not limited to implementations that overcome the disadvantages mentioned above or in other sections of this description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will become more understandable after reading the following description of non-limiting embodiments in conjunction with the accompanying drawings: Fig. Figure 1 shows a block diagram of a rail vehicle with a motor according to an embodiment of the invention. Fig. Figure 2 illustrates in a flowchart a method for controlling an exhaust gas flow passing through an exhaust gas recirculation system, according to an embodiment of the invention. Fig. Figure 3 illustrates in a flowchart a method for adjusting a recirculated exhaust gas flow based on a throttling level of a turbocharger according to an embodiment of the invention. Fig. Figure 4 shows a compressor map for a turbocharger according to an embodiment of the invention. DETAILED DESCRIPTION

[0019] The following description concerns various embodiments for adjusting the exhaust gas flow in an exhaust gas recirculation (EGR) system based on a turbocharger throttling level. Under certain ambient conditions, for example, when the ambient temperature exceeds a threshold temperature, or in the case of operation with restricted airflow (e.g., in a tunnel), the temperatures of the engine and cooling systems of a vehicle can rise. In some embodiments, the temperatures can rise considerably, leading to reduced power and engine overheating. During these conditions, the exhaust gas recirculation flow can be reduced to decrease the engine's cooling requirements, thereby increasing engine efficiency. The amount of the reduction in the recirculated exhaust gas flow can be based on a turbocharger throttling limit or level.This allows the exhaust gas recirculation flow to be maintained appropriately, so that the turbocharger operation does not exceed the throttling level.

[0020] The approach described here can be used in different types of motors and in a variety of motor-driven systems. Some of these systems may be stationary, while others may be located on semi-mobile or fully mobile platforms. Semi-mobile platforms may be set up elsewhere during periods of operation, for example, on flatbed wagons. Mobile platforms include self-propelled vehicles. Such vehicles may be road-bound transport vehicles and off-road vehicles (OHVs), the latter including mining equipment, watercraft, locomotives, and other rail vehicles. For a more thorough illustration, a locomotive is shown as an example of a mobile platform carrying a system that utilizes an embodiment of the invention.

[0021] Before discussing in more detail the approach of adjusting the exhaust gas flow through an EGR system, an example of a platform is presented where the engine system can be installed in a vehicle, e.g., a rail vehicle. For example, it shows Fig. Figure 1 shows a block diagram of an embodiment of a vehicle system 100, here represented as a rail vehicle 106 (e.g., a locomotive), which is designed to travel on many wheels 110 on a rail 102. As shown, the rail vehicle 106 includes a motor 104. In further embodiments, which are not considered limiting, the motor 104 can be a stationary motor, e.g., in a power plant application, or, as mentioned above, a motor in a watercraft or in another road-independent vehicle propulsion system.

[0022] The engine 104 draws intake air for combustion from an intake port, for example, from an intake manifold 115. The intake port can be any suitable channel or duct through which gases flow to enter the engine. For example, the intake port can include the intake manifold 115, the intake duct 114, and the like. The intake duct 114 draws in ambient air from an air filter (not shown), which filters air from the environment of a vehicle in which the engine 104 may be located. Exhaust gas produced by combustion in the engine 104 is directed to an exhaust system, such as an exhaust duct 116. The exhaust system can be any suitable duct through which the gas from the engine flows. For example, the exhaust system can include an exhaust manifold 117, the exhaust duct 116, and the like. Exhaust gas flows through the exhaust duct 116 and out of a chimney of the rail vehicle 106.In one example, engine 104 is a diesel engine that combusts air and diesel fuel by means of auto-ignition. In other embodiments, which are not considered limiting, engine 104 can, for example, combust gasoline, kerosene, biodiesel, or other petroleum distillates of similar density by means of auto-ignition (and / or by means of spark ignition).

[0023] In one embodiment, the rail vehicle 106 is a diesel-electric vehicle. As in Fig. As shown in Figure 1, the engine 104 is connected to an electrical power generation system that includes a generator 140 and electric drive motors 112. For example, the engine 104 is a diesel engine that generates torque which is transmitted to the generator 140, which is mechanically connected to the engine 104. The generator 140 produces electrical power that can be stored and used to subsequently supply various downstream electrical components. For example, the generator 140 can be electrically connected to several electric drive motors 112, and the generator 140 can supply electrical power to the several electric drive motors 112. As shown, each of the electric drive motors 112 is connected to one of several wheels 110 to provide tractive force for propelling the rail vehicle 106. One example arrangement includes one electric drive motor per wheel.As shown here, six pairs of electric drive motors each correspond to six pairs of wheels of the rail vehicle. In a further embodiment, the generator 140 can be connected to one or more resistance networks 142. The resistance networks 142 can be configured to dissipate excess motor torque as heat, which is generated by the networks from the electricity produced by the generator 140.

[0024] In the Fig. In the embodiment shown in Figure 1, the engine 104 is a V-12 engine with twelve cylinders. In other examples, the engine may be based on a V-6, V-8, V-10, V-16, I-4, I-6, I-8, opposed-piston 4, or other engine type. As shown, the engine 104 has a subset of non-donor cylinders 105, comprising six cylinders that feed exhaust gas exclusively to a non-donor cylinder exhaust manifold 117, and a subset of donor cylinders 107, comprising six cylinders that feed exhaust gas exclusively to a donor cylinder exhaust manifold 119. In further embodiments, the engine may include at least one donor cylinder and at least one non-donor cylinder. For example, the engine may have four donor cylinders and eight non-donor cylinders, or three donor cylinders and nine non-donor cylinders.It goes without saying that the engine can have any desired number of donor and non-donor cylinders, with the number of donor cylinders usually being smaller than the number of non-donor cylinders.

[0025] As in Fig. As shown in Figure 1, the non-donor cylinders 105 are connected to the exhaust port 116 to release exhaust gas (after passing through an exhaust aftertreatment system 130 and a turbocharger 124) from the engine into the atmosphere. The donor cylinders 107, which provide the engine exhaust gas recirculation (EGR), are connected exclusively to an EGR port 162 of an EGR system 160, which directs exhaust gas from the donor cylinders 107 to the intake port 114 of the engine 104, and not into the atmosphere. By introducing cooled exhaust gas to the engine 104, the proportion of oxygen available for combustion is reduced, which lowers flame temperatures during combustion and the formation of nitrogen oxides (e.g., NOₓ).x ) reduced.

[0026] Exhaust gas flowing from the donor cylinders 107 to the intake port 114 then flows through a heat exchanger, for example, an EGR cooler 166, to reduce the temperature of the exhaust gas (i.e., to cool it) before it returns to the intake port. The EGR cooler 166 can, for example, be an air-to-liquid heat exchanger. In such an example, a charge air cooler 134, located in the intake port 114 (e.g., upstream of the point where recirculated exhaust gas enters the circuit), can be adjusted to further cool the charge air so that the temperature of the charge air / exhaust mixture is maintained at a desired value. In other examples, the EGR system 160 can include an EGR cooler bypass channel. In a variation, the EGR system can include an EGR cooler control element.The EGR cooler control element can be actuated in such a way as to reduce the flow of exhaust gas through the EGR cooler; however, in such an arrangement, exhaust gas that does not flow through the EGR cooler is directed not to the intake channel 114 but to the exhaust channel 116.

[0027] Furthermore, in some embodiments, the EGR system 160 may include an EGR bypass channel 161, which is configured to divert exhaust gas from the donor cylinders back to the exhaust port. The EGR bypass channel 161 may be controlled by a valve 163. The valve 163 may be designed with multiple limiting points so that a variable amount of exhaust gas is diverted to the outlet to provide a variable amount of exhaust gas recirculation to the intake port.

[0028] In a Fig. In the modified embodiment shown in Figure 1, the donor cylinder 107 (illustrated by the dashed lines) can be connected to a modified EGR channel 165, which is configured to selectively branch exhaust gas to the intake port or to the exhaust port. For example, if a second exhaust gas recirculation valve 170 is open, exhaust gas can be branched from the donor cylinders to the EGR cooler 166 and / or to additional elements before being branched to the intake port 114. Furthermore, the modified EGR system includes a first exhaust gas recirculation valve 164, which is arranged between the exhaust port 116 and the modified EGR channel 165.

[0029] The first exhaust gas recirculation valve 164 and the second exhaust gas recirculation valve 170 can be on / off valves controlled by the monitoring unit 180 (to switch the EGR flow on or off), or they can, for example, control a variable amount of exhaust gas recirculation. Accordingly, the valves can be moved into several positions between fully open and fully closed. In some embodiments, the first exhaust gas recirculation valve 164 can be actuated to decrease the amount of EGR (exhaust gas flows from the exhaust gas recirculation channel 165 to the exhaust gas channel 116). For example, the opening of the first exhaust gas recirculation valve 164 can be increased to increase the exhaust gas flow from the donor cylinders to the exhaust gas channel 116. In other examples, the first exhaust gas recirculation valve 164 can be actuated to increase the amount of EGR (i.e.,Exhaust gas flows from the exhaust port 116 to the exhaust gas recirculation port 165. For example, the opening of the first exhaust gas recirculation valve 164 can be reduced to decrease the flow to the exhaust port 116. In another embodiment, the second exhaust gas recirculation valve 170 can be actuated to reduce the amount of EGR. For example, closing the second exhaust gas recirculation valve 170 can reduce the exhaust gas flow from the donor cylinders to the intake port 114. In some embodiments, the modified EGR system can include multiple exhaust gas recirculation valves or other flow control elements to control the amount of EGR.

[0030] In such a design, the first exhaust gas recirculation valve 164 is configured to branch exhaust gas from the donor cylinders to the exhaust port 116 of the engine 104, and the second exhaust gas recirculation valve 170 is configured to branch exhaust gas from the donor cylinders to the intake port 114 of the engine 104. In this sense, the first exhaust gas recirculation valve 164 can be referred to as an EGR bypass valve, while the second exhaust gas recirculation valve 170 can be referred to as an EGR metering valve. In the Fig. In the embodiment shown in Figure 1, the first exhaust gas recirculation valve 164 and the second exhaust gas recirculation valve 170 can be valves actuated by engine oil or hydraulically, wherein, for example, a (not shown) changeover valve modulates the engine oil. In some embodiments, the valves can be actuated such that either the first or the second exhaust gas recirculation valve 164 and 170 is normally open, and the other is normally closed. In other examples, the first and second exhaust gas recirculation valves 164 and 170 can be pneumatic valves, electric valves, or other suitable valves.

[0031] As in Fig. As shown in Figure 1, the vehicle system 100 also includes an EGR mixer 172, which mixes the recirculated exhaust gas with charge air so that the exhaust gas can be evenly distributed in the charge air and exhaust gas mixture. In the Fig. In the embodiment shown in Figure 1, the EGR system 160 is a high-pressure EGR system that directs exhaust gas from a point upstream of the turbocharger 124 in the exhaust channel 116 to a point downstream of the turbocharger 124 in the intake channel 114. In further embodiments, the vehicle system 100 can additionally or alternatively include a low-pressure EGR system that directs exhaust gas from downstream of the turbocharger 124 in the exhaust channel 116 to a point upstream of the turbocharger 124 in the intake channel 114.

[0032] As in Fig. As shown in Figure 1, the vehicle system 100 also includes a turbocharger 124, which is arranged between the intake port 114 and the exhaust port 116. The turbocharger 124 increases the charging with ambient air drawn into the intake port 114 to provide a higher charge density during combustion in order to increase the output power and / or engine efficiency. The turbocharger 124 includes a turbine 125, which drives a compressor 126. The turbine 125 and the compressor 126 are mechanically connected via a shaft 127. In some embodiments, the vehicle system 100 can include a two-stage turbocharger, with the two turbochargers connected in series. A first turbocharger (e.g., a low-pressure turbocharger) can operate at a relatively lower pressure, while a second turbocharger (e.g., a high-pressure turbocharger) can operate at a relatively high pressure.In some embodiments, a two-stage turbocharger can include: a high-pressure turbocharger and a low-pressure turbocharger connected in series; three turbochargers connected in series; two low-pressure turbochargers feeding a high-pressure turbocharger; a low-pressure turbocharger feeding two high-pressure turbochargers; or the like. One example uses three turbochargers connected in series. Another embodiment uses only two turbochargers connected in series.

[0033] As explained above, the terms "high pressure" and "low pressure" are relative; that is, a "high" pressure is a pressure that is higher than a "low" pressure. Conversely, a "low" pressure is a pressure that is lower than a "high" pressure.

[0034] In the Fig. In the embodiment shown in Figure 1, the turbocharger 124 is provided with a turbine bypass valve 128, which allows exhaust gases to bypass the turbocharger 124. The turbine bypass valve 128 can, for example, be opened to divert the exhaust gas flow from the turbine 125. In this way, the speed of the compressor 126, and thus the boost supplied to the engine 104 by the turbocharger 124, can be regulated during stable continuous operating conditions. Furthermore, in this embodiment, the turbocharger 124 is provided with a compressor bypass valve 129, which allows gas to bypass the second compressor 126, for example, to avoid compressor pressure surges. In some embodiments, the turbocharger 124 may not have a compressor bypass valve 129.

[0035] The operation of the turbocharger 124 can be maintained within the turbocharger's pressure surge and throttling limits, thereby increasing the turbocharger efficiency. The power output of the compressor 126 of the turbocharger 124 can be defined by a characteristic map that defines the relationship between a compressor pressure ratio (e.g., the ratio of the absolute pressure at the compressor outlet to the absolute pressure at the compressor inlet) and an airflow mass flow rate (e.g., the airflow mass flow rate). An example of a compressor power characteristic map 400 is shown in Fig. Figure 4 shows the compressor pressure ratio on the y-axis and the airflow mass flow rate on the x-axis. The dashed lines in the map are turbine speed characteristics 406, representing different speeds of the turbine 125. The compressor power is limited by a pressure surge characteristic 402 and a throttling characteristic 404. At each turbine speed, there is a pressure surge limit or pressure surge level and a throttling limit or throttling level, each corresponding to a compressor pressure ratio and airflow mass flow rate. The compressor power can be maintained between the pressure surge characteristic 402 and the throttling characteristic 404 to increase turbocharger efficiency and reduce turbocharger wear. The pressure surge level can be defined as the limitation of the airflow mass flow rate at the compressor inlet 126.If the compressor pressure ratio is too high and the airflow mass flow rate is too low, the airflow through the compressor can stop and reverse direction until the pressure stabilizes and the positive airflow mass flow rate is reached again. This flow instability can cause pulsation and result in a disturbance known as a "pressure surge." A throttling level can represent a maximum airflow mass flow rate through the compressor under any operating condition. The throttling level can be due to the cross-sectional area of ​​the compressor inlet.

[0036] The compressor power map 400 can be generated by a turbocharger test. Accordingly, a compressor power map, such as the one in Fig. Figure 4 shows a characteristic map for the turbocharger 124, which is stored in a control unit 180 of the vehicle system 100. According to the embodiments described here, the control unit 180 can adjust the EGR within a range of a throttling level of the compressor 126. As the exhaust gas recirculation decreases, the air mass flow rate increases, which moves the turbocharger operation to the right on the compressor characteristic map. For example, the exhaust gas flow through the EGR system can be reduced in response to an ambient condition. The amount of the reduction can be based on the throttling level at the current compressor operating state. Accordingly, the EGR rate can be reduced to a level such that the air mass flow rate increases up to a rate within a threshold range of the throttling level (shown as T1 in the compressor performance map 400).The threshold can be a value of the airflow mass flow rate that reduces the probability of compressor throttling. Details regarding the control of the EGR rate based on the throttling level and the compressor power map are discussed further below with reference to [reference missing]. Fig. 2-4 explained in more detail. Further details for the in Fig. The compressor output shown in the four figures is explained below.

[0037] By returning to Fig. As discussed in Figure 1, the vehicle system 100 also includes an exhaust aftertreatment system 130, which is integrated into the exhaust duct to reduce prescribed emissions. As shown in Figure 1, the exhaust aftertreatment system 130 is located downstream of the turbine 125. The exhaust aftertreatment system 130 can contain one or more components. For example, the exhaust aftertreatment system 130 can include a diesel particulate filter (DPF), a diesel oxidation catalyst (DOC), a selective catalytic reduction (SCR) catalyst, a three-way catalyst, or a NOₓ catalyst. x -Includes separators and / or various other emission monitoring devices or combinations thereof.

[0038] The vehicle system 100 also includes the control unit 180, which is designed and configured to control various components associated with the vehicle system 100. In this example, the control unit 180 may be referred to as the controller. In one example, the control unit 180 includes a computer control system. The control unit 180 also includes non-volatile, computer-readable storage media (not shown) containing code to enable monitoring and control of the onboard engine operation. While the control unit 180 oversees the control and management of the vehicle system 100, it may, as further explained below, receive signals from various engine sensors to determine operating parameters and conditions, and adjust various engine actuators accordingly to control the operation of the vehicle system 100.For example, the control unit 180 can receive signals from various engine sensors, including: a sensor 181 located in the inlet of the turbine 125, a sensor 182 located in the outlet of the turbine 125, a sensor 183 located in the inlet of the compressor 126, and a sensor 184 located in the outlet of the compressor 126. The sensors located in the inlets and outlets of the turbine and compressor can detect the temperature and / or pressure of the air. Additional sensors can, but are not limited to, measure engine speed, engine load, boost pressure, ambient pressure, exhaust gas temperature, exhaust gas outlet pressure, exhaust flow, turbine speed, air mass flow rate, EGR flow rate, or the like.In accordance with this, the control unit 180 can control the vehicle system 100 by transmitting control commands to different components, such as electric drive motors, a generator, cylinder valves, a throttle, heat exchangers, exhaust bypass valves or other valves or flow control elements, or the like.

[0039] As another example, the control unit can receive signals from one or more intake gas component sensors 146 (e.g., with regard to O2, NO). xSensors 146 measure the concentrations of intake gas components (e.g., CO2 and the like) and are located in the intake duct 114. The sensors 146 can be positioned at various locations within the intake duct 114, for example, upstream of the turbocharger 120 and / or downstream of the turbocharger compressor, as well as upstream of the EGR inlet and / or downstream of the EGR inlet to the intake system. Furthermore, the sensors 146 can be connected to the intake port of all cylinders of the engine, or a subset of the engine cylinders, or a single cylinder of the engine. For example, an intake oxygen fraction or percentage can be obtained from sensors 146. This intake oxygen fraction can then be used by the control unit to adjust the valves in the EGR system to provide a specific exhaust gas recirculation flow rate or quantity.

[0040] The control unit can also receive signals from one or more exhaust gas component sensors 132, 144 arranged in the exhaust gas duct or EGR duct (e.g. with regard to O2, NO). x The exhaust gas sensors 132, 144 can be located at various points in the exhaust gas channel 116, for example, upstream and / or downstream of the turbocharger turbine, and / or upstream and / or downstream of the EGR port. Furthermore, the sensors 132, 144 can be connected to the exhaust of all cylinders of the engine, or a subset of engine cylinders, or a single cylinder of the engine.

[0041] In one example, tunnel operation or other operation in restricted airflow can be determined based on these sensors. Operation in restricted airflow could be engine operation where the vehicle system moves through a space with restricted airflow, such as a physical tunnel. However, other spaces with restricted airflow are also possible, such as in a mine or in buildings. For example, ambient air (e.g., the air surrounding the vehicle when the vehicle is not operating in a tunnel) contains approximately 0% NO. x and 21% O2. During operation in a tunnel, where a significant amount of exhaust gas may be present in the immediate vicinity inside the tunnel, the intake gases introduced by the engine can contain additional exhaust gas (e.g., exhaust gas recirculation / EGR from the tunnel environment) and thus increased NO. x- and exhibit reduced O2 levels. This engine-induced change in the surrounding gases can lead to an increase in the concentration of NO. x in the intake manifold and to a decrease in the concentration of NO x in the exhaust duct, and / or lead to a decrease in the O2 concentration in both the intake and exhaust ducts. In response to receiving a signal indicating that an intake or exhaust gas concentration is too low or too high (e.g., above or below expected threshold values), a tunnel operating condition can be reported, and the control unit 180 can adjust an operating parameter. For example, the control unit 180 can adjust one or more exhaust gas recirculation valves to reduce the EGR quantity in response to a tunnel operating condition report.

[0042] In another embodiment, the control unit 180 can calculate the geographic coordinates of the rail vehicle 106 using signals output by a position sensor, e.g., a Global Positioning System (GPS) receiver 154. The geographic coordinates of the vehicle 106 can be estimated or calculated. For example, a GPS signal from the GPS receiver 154 can be used to calculate the vehicle's geographic coordinates. Geographic features along the route of the vehicle, e.g., the rail vehicle 106, can be reported or calculated by a user. For example, the geographic coordinates of a set of predefined geographic features can be stored in a table. A distance between the vehicle and the set of predefined geographic features can be calculated so that the next geographic feature and its distance can be determined.Non-restrictive examples of geographic features that can be stored in the set of predefined geographic features include a tunnel entrance, a steep incline, and a city boundary. Furthermore, the GPS can contain stored data regarding the predefined geographic features, such as the length of a tunnel and its gradient.

[0043] In one embodiment, the control unit can identify tunnel conditions based on changes in the engine's intake gas and / or exhaust gas components and / or cause the rail vehicle to adjust one or more operating parameters when one or more intake gas and / or exhaust gas component sensors of the engine indicate a tunnel operating condition. For example, the control unit can indicate a tunnel operating condition when the concentration of a component in the intake gas and / or exhaust gas exceeds a threshold concentration. The control unit can also contain commands that serve to adjust one or more engine operating parameters, such as the EGR amount or rate, depending on the tunnel operating condition indication. In another embodiment, the control unit can identify a tunnel operating condition or predict the presence of a tunnel using a GPS receiver.

[0044] The system of Fig. 1. On board a vehicle, an engine system can be provided that includes a turbocharger with a compressor, an exhaust gas recirculation (EGR) system with an EGR valve that controls the exhaust gas flow through the EGR system, and a control unit. In one example, the control unit is configured to adjust the EGR valve to reduce the exhaust gas flow through the EGR system in response to an environmental condition, the reduction being based on a throttling level of the compressor. The environmental condition can include an ambient temperature exceeding a threshold temperature and / or restricted airflow of the vehicle moving through a space with restricted airflow, e.g., a tunnel.

[0045] When a vehicle enters a tunnel or other space with restricted airflow, the reduced ventilation in the tunnel can cause the vehicle's systems to repeatedly draw in exhaust gases. As a result, the intake air entering the engine is warmer, and the engine temperature rises. As the engine temperature increases, it may approach a thermal limit or threshold at which engine power decreases. The thermal threshold may be defined by an engine component overheating, such as an oil temperature, coolant temperature, and / or exhaust gas temperature exceeding a specified threshold temperature. As discussed above, the control unit may reduce the exhaust gas flow (e.g., the exhaust gas recirculation flow) through the EGR system in response to tunnel operating conditions.Reducing the exhaust gas recirculation flow can reduce excess heat originating from the exhaust gases introduced into the intake manifold 114. As a result, the cooling requirements of the engine system 100, such as the cooling requirements of the charge air cooler, can be reduced. Furthermore, reducing the exhaust gas recirculation flow can reduce the heat load exerted on the vehicle's cooling system by the EGR cooler 166. For these reasons, reducing the exhaust gas recirculation flow can increase the efficiency of the engine and maintain engine power.

[0046] In addition to reducing the exhaust gas recirculation flow in response to a tunnel operating condition, the exhaust gas recirculation flow can also be reduced in response to another ambient condition. This other condition might involve the ambient temperature exceeding a threshold temperature. As such, reducing the exhaust gas recirculation flow can increase the efficiency of the drive motor if the ambient temperature is relatively high and exceeds the threshold.

[0047] The reduction in exhaust gas recirculation (EGR) flow in response to one or more of the aforementioned environmental conditions can be based on the turbocharger's throttling level. Specifically, the EGR flow can be reduced to a first level in response to the environmental condition. This first level is based on the throttling level at a current compressor pressure ratio and turbocharger speed (e.g., turbine speed). The first level can be the EGR flow rate that increases the airflow mass flow until it falls within a threshold range of the throttling level.

[0048] An example of reducing the exhaust gas recirculation flow to within a threshold range of the throttling level is in Fig. Figure 4 illustrates this on the compressor performance map 400. In one example, the turbocharger might initially operate at location 408 at a first turbine or turbocharger speed 412 when the vehicle enters a tunnel. In response to the tunnel operating condition, the control unit reduces the exhaust gas recirculation flow to a first level, which moves the compressor operation to location 410 on the map. Location 410 is within a threshold range T1 of the throttling level 424 at the first turbine speed 412. The first level can be based on the pressure ratio across the compressor (e.g., compressor pressure ratio) and on the turbocharger speed.

[0049] While the tunnel operating condition persists, the engine temperature may continue to rise. When a thermal limit or threshold is finally reached, the engine power may be reduced. This can change where the compressor operates on compressor power map 400. The compressor pressure ratio may decrease, causing the compressor operation to move to location 414 on the map at a second turbine speed 418. Location 414 is now at an extended tolerance margin of a set throttling level 426 at the second turbine speed 418. In response to the reduction in engine power and the resulting increase in the tolerance margin from the throttling level, the control unit reduces the exhaust gas recirculation flow to a second level. The second level increases the airflow mass flow rate and moves the compressor operation to location 416 on the map.Location 416 is within a threshold range T1 of the set throttling level 426 at the second turbine speed 418. The EGR flow is reduced by a first amount for the first reduction (location 408 to location 410) and by a second amount for the second reduction (location 414 to location 426). In this example, the first amount can be greater than the second amount. This is because a first tolerance range 420 of the throttling level 424 is greater than a second tolerance range 422 of the set throttling level 418. Accordingly, the amount by which the exhaust gas flow is reduced increases as the tolerance range of the throttling level increases.

[0050] The in Fig. Example 4 illustrates two operating points of a turbocharger. In further embodiments, a reduction of the exhaust gas recirculation flow to within a threshold range T1 of a throttling level can be implemented for a variety of other turbocharger operating conditions. For example, the turbine speed, the air mass flow rate, and the compressor pressure ratio of the turbocharger may be higher or lower during operation. Accordingly, the exhaust gas recirculation flow can be reduced by varying the quantities depending on the tolerance margin from the throttling level under those operating conditions. Further details of a method for reducing an exhaust gas recirculation flow based on a throttling level are given below with reference to Fig. 3 submitted.

[0051] In this way, the exhaust gas flow in an engine's EGR system can be reduced in response to an ambient condition, down to a threshold level of a turbocharger throttling point. For example, the ambient condition could be the ambient temperature, and the reduction in exhaust gas flow could occur when the ambient temperature exceeds a threshold. In another embodiment, the ambient condition could be based on operation in a restricted airflow area, and the reduction in exhaust gas flow could occur when a vehicle enters the restricted airflow area. For example, the restricted airflow area could include a tunnel, and the ambient condition could therefore be a tunnel operating condition.In another embodiment, the restricted airflow area can be any other enclosed area in which the airflow to the vehicle is restricted compared to the vehicle outside the enclosed area. The exhaust flow can be reduced to a first level, the first level being based on the throttling level at a current compressor pressure ratio and turbocharger speed. While the tunnel operating condition persists, engine power may be reduced due to overheating of an engine component. In response to the reduction in engine power and the resulting increase in a tolerance margin, the exhaust flow can be further reduced from the throttling level to a second level. The reduction in engine power may be due to overheating of an engine component, for example, an oil temperature.

[0052] Fig. Figure 2 shows a procedure 200 for controlling the exhaust gas flow through the EGR system (referred to here as EGR flow). The procedure can be executed by the control unit according to commands stored on it. The procedure begins in step 202 by determining engine operating parameters. The engine operating parameters may include: engine speed and load, oil temperature, exhaust gas temperature, coolant temperature, tunnel operating conditions, ambient temperature, exhaust gas recirculation rate or quantity, intake oxygen fraction, air mass flow rate, compressor pressure ratio, turbine speed, and the like. In step 204, the control unit determines whether the ambient temperature exceeds a threshold temperature. The threshold temperature may be based on a temperature that can raise engine temperatures up to a thermal threshold, leading to engine overheating.The thermal threshold can include the threshold temperatures at which the engine begins to lose power. Engine temperatures can include oil temperature, engine coolant temperature, and / or exhaust gas temperature.

[0053] If, in step 204, the ambient temperature is higher than the threshold temperature, the procedure proceeds to step 210 to adjust one or more exhaust gas recirculation (EGR) valves to provide the EGR flow based on a turbocharger throttling level. This may involve adjusting the EGR valves to decrease the EGR flow so that the mass airflow increases to within a threshold range or tolerance margin of the throttling level. For example, the second EGR valve 170 may be closed, or the valve opening may be reduced, to decrease the EGR flow. Further details of the procedure in step 210 are given below with reference to Fig. 3 explained.

[0054] Referring again to step 204, if the ambient temperature in step 204 does not exceed the threshold temperature, the procedure proceeds to step 206 to determine whether the vehicle is operating in a tunnel or in another space with restricted airflow. In one example, determining tunnel operation may involve using a GPS receiver to ascertain whether the vehicle is in or approaching a tunnel. In another embodiment, determining tunnel operation may involve obtaining component concentrations from the engine's intake gases and / or exhaust gases to determine tunnel operation. If the vehicle is neither near nor inside a tunnel, the procedure proceeds to step 208 to adjust the exhaust gas recirculation (EGR) valves to provide EGR for a predetermined intake oxygen fraction.This can involve increasing or decreasing the opening of one or more exhaust gas recirculation (EGR) valves to increase or decrease the EGR flow. However, if the vehicle is operating in a tunnel, the procedure continues with step 210 to adjust the one or more EGR valves to supply the EGR flow based on a turbocharger throttling level. In this way, the EGR flow can be controlled in response to an ambient condition, such as whether the ambient temperature exceeds a threshold and / or whether a tunnel operating condition exists.

[0055] Fig. Figure 3 illustrates a procedure 300 for adjusting the exhaust gas recirculation flow based on a turbocharger throttling level. The procedure can be executed by the control unit according to commands stored on it. The procedure begins in step 302 by determining the pressure ratio across the compressor (e.g., the compressor pressure ratio), the turbocharger speed (e.g., the turbine speed), and the airflow mass flow rate. In step 304, the control unit determines the throttling level for the operating point on a compressor map, e.g., on the one shown in Figure 304. Fig. 4. Compressor performance map shown. For example, the control unit can determine the operating point on the compressor map based on the current airflow mass flow rate, the compressor pressure ratio, and / or the turbine speed. This may involve determining the tolerance margin of an airflow mass flow rate from the throttling level. For example, the control unit may determine that the amount of airflow mass flow rate can be increased and that the exhaust gas recirculation flow must be reduced accordingly to move the compressor operation into a throttling level threshold range. Subsequently, in step 306, the control unit reduces the exhaust gas recirculation flow to increase the airflow mass flow rate until it is within a throttling level threshold range.As discussed above, the threshold can be a quantity of airflow mass flow rate that reduces the probability of compressor throttling. This threshold can be increased or decreased depending on an appropriate risk of compressor pressure surge. For example, if a reduction in drive engine efficiency due to power loss is greater than a reduction in turbocharger efficiency due to pressure surge, the threshold can be lower.

[0056] In step 308, the procedure involves determining whether the engine system is at a thermal limit or threshold. This may include determining whether the oil temperature, exhaust gas temperature, or coolant temperature exceeds a corresponding threshold temperature. For example, if the oil temperature exceeds a threshold temperature, the engine system may be at a thermal threshold. If the engine system is not at or above this threshold, the control unit does not reduce engine power and continues monitoring engine operating conditions in step 310. However, if the engine system is at or above the thermal threshold in step 308, engine power is reduced in step 312. The degree of power reduction can be determined depending on the component experiencing an overheating condition.For example, a greater power reduction may occur during an overheating condition of a first component, and a lesser power reduction may occur during an overheating condition of a second, different component, the second of which is experiencing a more severe wear condition. Furthermore, the amount of power reduction may be due to engine operating conditions, vehicle driving conditions, and combinations thereof. Additionally, multiple successive power reduction events may occur in response to the successive attainment of overheating conditions by different components, as described here. For instance, during operation, a first component may reach its overheating limit, resulting in an initial power reduction, causing the engine to operate at a reduced power output.Later, while the first power reduction is still in effect, a second component may reach its overheating limit, leading to a second further power reduction. As a result, the motor operates at a second reduced power level, which is lower than the first. Since the procedure 300 is repeatedly executed in real-time processing, the subsequent control of the throttling level can thus be performed for each power reduction event.

[0057] As the engine power decreases, the turbine speed and air mass flow rate also decrease, thereby reducing the compressor pressure ratio and changing the operating point on the compressor map. This, in turn, changes the throttling level from the original throttling level to a set throttling level. The procedure in step 314 includes the step of determining the set throttling level for the new operating condition of the turbocharger. This may involve measuring the air mass flow rate, the compressor pressure ratio, and the turbine speed, and then setting the throttling level based on the operating position on the compressor map stored in the control unit, e.g., the one in Fig. to determine the compressor map shown in section 4.

[0058] Step 316 involves determining whether the turbocharger operating condition deviates from the set throttling level by a tolerance range. For example, the tolerance range from the throttling level could be an airflow mass flow rate that is greater than the threshold value of the throttling level described above (T1 in Fig.4) In another embodiment, the tolerance margin from the throttling level can be a larger amount of the airflow mass flow rate. The tolerance margin from the throttling level for reducing the exhaust gas recirculation flow can be based on a minimum increase in airflow mass flow rate resulting from a reduction in EGR. Specifically, the exhaust gas recirculation flow can be reduced if it can be reduced by a tolerance range without causing the turbocharger operation to exceed a threshold within the throttling limit. If the turbocharger operation is not within a tolerance margin of the throttling level, the control unit does not reduce the exhaust gas recirculation flow and continues monitoring the engine operating conditions in step 324.However, if the turbocharger operation is located a tolerance distance away from the throttling level, the control unit reduces the exhaust gas recirculation flow in step 318 in order to increase the airflow mass flow rate to within a threshold range of the set throttling level.

[0059] In step 320, the control unit determines whether the ambient temperature falls below the threshold temperature or whether the vehicle has left the tunnel. If either of these conditions is met, the exhaust gas recirculation flow is reset to a level based on the intake oxygen content. However, if neither of these conditions is met, the procedure continues monitoring the engine operating conditions in step 326 and returns to the procedure in step 308 to check again whether the engine system is approaching a thermal threshold.

[0060] Thus, the exhaust gas flow through an EGR system can be adjusted based on a turbocharger's throttling level. The exhaust gas recirculation flow can be reduced in response to an ambient condition, which may include exceeding a threshold due to ambient temperature and / or tunnel operating conditions. As the ambient condition persists, engine power may be reduced to the extent that the engine system reaches a thermal threshold. Consequently, turbocharger operation may change, and the tolerance margin from the throttling level may increase. In response, the exhaust gas recirculation flow can be further reduced until it falls within a threshold range of the new, set throttling level. Therefore, the exhaust gas recirculation flow can be reduced to improve turbine performance during an ambient condition while maintaining turbocharger efficiency.

[0061] Furthermore, as mentioned above, the procedure can continue successive power reductions and corresponding repeated adjustments of the EGR with regard to set throttling tolerance margins. For example, the exhaust gas recirculation flow can be reduced by an initial amount in response to an ambient condition, which may include an ambient temperature above a threshold temperature and / or a tunnel operating condition. As the ambient condition persists, the engine power can be reduced by an initial amount up to an initial level as the engine system reaches an initial thermal threshold, in order to mitigate the overheating of a component. Consequently, the turbocharger operation may change, and the tolerance margin from the throttling level may increase by an initial amount.In response, the exhaust gas recirculation flow can be further reduced by a second amount until it falls within a threshold range of the new, first set throttling level. While the ambient condition persists and the engine power remains at the first level, the engine power can be further reduced by a second amount until it reaches a second level (lower than the first level) as the engine system reaches a second thermal threshold, in order to reduce overheating of a second component, different from the first. As a result, the turbocharger operation may change again, and a tolerance margin from the throttling level may increase by a second amount. In response, the exhaust gas recirculation flow can be reduced again by a third amount until it falls within a threshold range of the new, second set throttling level.Thus, the EGR can be reduced to a first level, and subsequently to a second, lower level, in order to maintain the tolerance margin to the pressure surge and to help reduce overheating conditions.

[0062] One embodiment relates to a method (e.g., a method for controlling an engine) comprising the step of controlling an exhaust gas flow by an exhaust gas recirculation system of an engine system based on a turbocharger throttling level. For example, the exhaust gas flow control step may involve reducing the exhaust gas flow in response to an environmental condition until it falls within a threshold range of the turbocharger throttling level.

[0063] In another embodiment of the method, the amount by which the exhaust gas flow is reduced increases in proportion to the increase in the tolerance margin from the throttling level.

[0064] In another embodiment of the method, the ambient condition is an ambient temperature. The exhaust gas flow is reduced in response to the ambient temperature exceeding a threshold temperature.

[0065] In another embodiment of the method, the environmental condition is based on a vehicle in which the engine is installed and which enters an area of ​​restricted airflow.

[0066] In another embodiment of the method, the method additionally includes the step of resetting the exhaust gas flow to a level based on a predetermined intake oxygen fraction when the vehicle leaves the area of ​​restricted airflow.

[0067] In a further embodiment of the method, the process also includes the step of reducing the exhaust gas flow to a first level. The first level is based on the throttling level at a current compressor pressure ratio and turbocharger speed. In other embodiments, the method can also include the step of reducing engine power in response to overheating of an engine component. In still further embodiments, the method can also include the step of further reducing the exhaust gas flow from the throttling level to a second level in response to the reduction in engine power and the resulting increase in a tolerance margin.

[0068] Another embodiment relates to a system. The system includes: a turbocharger incorporating a compressor, an exhaust gas recirculation (EGR) system, an EGR valve for controlling the exhaust gas flow through the EGR system, and a control unit. The control unit is configured to adjust the EGR valve to reduce the exhaust gas flow through the EGR system in response to an ambient condition and based on a compressor throttling level. For example, the ambient condition may involve an ambient temperature exceeding a threshold temperature and / or a vehicle on which the system is mounted entering an area of ​​restricted airflow (e.g., a tunnel operating condition of the vehicle).

[0069] In the sense used here, singular elements or steps preceded by the indefinite article should be understood to mean that the plural of the elements or steps is not excluded, unless such exclusion is expressly stated. Furthermore, reference to "an embodiment" of the present invention should not be interpreted as excluding the existence of additional embodiments that also embody the listed features. Moreover, embodiments that "include," "contain," or "exhibit" one or more elements with a special property may include further such elements, unless expressly stated otherwise. The terms "containing" and "in which" are used as generic equivalents of the corresponding terms "exhibiting" and "whereby."Furthermore, the terms "first", "second", "third" and the like are used merely for identification and are not intended to impose any numerical requirements or a specific order of arrangement on their objects.

[0070] The present description uses examples to describe the invention, including the best mode, and furthermore to enable a person skilled in the art to put the invention into practice, for example, to manufacture and use any devices and systems, and to carry out any related processes. The patentable scope of the invention is defined by the claims and may include further examples that a person skilled in the art might think of. Such other examples shall fall within the scope of the claims if they have structural elements that do not differ from the literal content of the claims, or if they contain equivalent structural elements with insignificant differences from the literal content of the claims.

[0071] Various methods and systems have been developed for adjusting the exhaust gas flow in an exhaust gas recirculation (EGR) system. In one embodiment, a method for an engine includes the step of controlling the exhaust gas flow through an EGR system based on the turbocharger's throttling level. For example, the exhaust gas flow in the EGR system can be reduced in response to an environmental condition down to a threshold value within the turbocharger's throttling level.

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