TWI741490B - Control system and control method - Google Patents

Abstract

A control system includes an electric heater disposed within an exhaust fluid flow pathway, and a control device for receiving at least one input selected from the group consisting of temperature readings along the exhaust fluid flow pathway, alternator power/current/voltage, battery power/current/voltage/state of charge, IAT and EAT profiles, mass flow rate of an exhaust fluid flow, NH₃ slip, TCR characteristics of the heater, alternator speed, engine speed, state of aging of an aftertreatment component, state of aging of engine, aging degradation characteristics, a dosing rate and a temperature of DEF, NH₃ storage condition of aftertreatment system, an ambient temperature, and combinations thereof. The control device modulates power to the heater based on the at least one input such that the heater provides a continuously variable heating output during operation of the exhaust system.

Description

Control system and control method

Cross-reference of related applications

This application claims the priority and rights of 16/260,507 filed on January 29, 2019, which is a partial continuation of the U.S. Patent Application No. 15/447,942 filed on March 2, 2017. The patent application The case claims the priority and rights of U.S. Provisional Application No. 62/302,482 filed on March 2, 2016, and the contents of these applications are fully incorporated herein by reference.

Field of invention

This disclosure relates to heating and sensing systems for fluid flow applications, such as vehicle exhaust systems, such as diesel exhaust and aftertreatment systems.

Background of the invention

The description in this chapter only provides background information related to the content of this disclosure, and does not constitute prior art.

Due to harsh environmental conditions such as vibration and thermal cycling, the use of physical sensors in transient fluid flow applications such as the exhaust system of an engine is challenging. A known temperature sensor includes a mineral insulated sensor inside a thermowell, which is welded to a support bracket that holds a tubular element. Unfortunately, this design takes a lot of time to achieve stability, and a high vibration environment can cause damage to the physical sensor.

The physical sensor also exhibits some inaccuracy of the actual resistive element temperature in many applications Qualitative, and as a result, a large safety margin is often used in the design of heater power. Therefore, heaters for physical sensors generally provide lower watt density, which allows a lower risk of damage to the heater at the expense of larger heater size and cost (in more resistive element surface area) The same heater power distributed on the above).

In addition, the known technology uses on/off control or PID control from an external sensor in the thermal control loop. The external sensor has an inherent delay from the thermal resistance between its wire and the output of the sensor. Any external sensor increases the possibility of component failure mode and is set to the limit of any mechanical support of the overall system.

One application of heaters in fluid flow systems is vehicle exhaust, which is coupled to an internal combustion engine to assist in reducing the undesirable release of various gases and other pollutants into the atmosphere. These exhaust systems typically include various aftertreatment devices, such as diesel particulate filters (DPF), catalytic converters, selective catalytic reduction (SCR), diesel oxidation catalysts (DOC), lean oil nitrogen oxide traps (LNT), ammonia escape catalyst or reformer, plus others. DPF, catalytic converter and SCR capture carbon monoxide (CO), nitrogen oxide (NOx), particulate matter (PM) and unburned hydrocarbons (HC) in exhaust gas. The heater may be activated periodically or at a predetermined time to increase the exhaust gas temperature, and activate the catalyst and/or burn particulate matter or unburned hydrocarbons that have been trapped in the exhaust system.

The heater is usually installed in an exhaust pipe or a component such as a container of an exhaust system. The heaters may include multiple heating elements in the exhaust pipe, and are typically controlled to the same target temperature to provide the same heat output. However, due to different operating conditions (such as different heat radiation from adjacent heating elements, and different temperatures of exhaust gas flowing through the heating elements), temperature gradients typically occur. For example, the downstream heating element usually has a higher temperature than the upstream element because the downstream heating element is exposed to a fluid having a higher temperature that has been heated by the upstream heating element. In addition, the intermediate heating element receives more heat radiation from adjacent upstream and downstream heating elements.

The life of the heater depends on the heater that is under the most severe heating conditions and will fail first. The life of the thermal element. Without knowing which heating element will fail first, it is difficult to predict the life of the heater. In order to improve the reliability of all heating elements, heaters are typically designed to operate with a safety factor to avoid failure of any one of the heating elements. Therefore, heating elements under less severe heating conditions are typically operated to produce a heat output that is much lower than their maximum available heating output.

Summary of the invention

In one form, a control system for a heating system of an exhaust system is provided. The control system includes at least one electric heater arranged in a discharge fluid flow path, and a control device adapted to receive at least one input. The at least one input is selected from the group consisting of: temperature readings along the discharge fluid flow path, alternator power, alternator current, alternator voltage, battery power, battery current, battery voltage, Battery state of charge, intake air throttle (IAT) and exhaust throttle (EAT) configurations, exhaust gas recirculation (EGR), mass flow rate of exhaust fluid flow, NH ₃ escape, the at least one electric heating The temperature coefficient of resistance (TCR) characteristics, alternator speed, engine speed, aging status of post-processing components, engine aging status, aging degradation characteristics, dosing rate of diesel exhaust fluid (DEF), DEF temperature, _{NH 3} storage status, injection timing delay, cylinder shut-off, variable valve operation, turbocharger bypass, intake air preheating, post-injection in the cylinder, ambient temperature, ambient temperature and their combinations in the aftertreatment system. The control device is operable to modulate the power to the at least one electric heater based on the at least one input, so that as the at least one input changes, a different heating output is provided by the at least one electric heater, and the at least one The electric heater provides a continuously variable heating output during the operation of the exhaust system.

From the description provided in this article, additional application areas will become apparent. It should be understood that the description and specific examples are only intended for illustrative purposes, and are not intended to limit the scope of the disclosure.

10: Engine system

12: Diesel engine

14: Alternator

16: turbocharger

18: Exhaust aftertreatment system

20: heating system

22: Diesel oxidation catalyst (DOC)

24: Diesel Particulate Filter (DPF)

26: Selective Catalytic Reduction (SCR)

27: Urea aqueous solution injector

28: heater assembly

30: Heater control module

31: control device

32: Upstream exhaust pipe

34: Intermediate exhaust pipe

36: Downstream exhaust pipe

40: Tubular heater, heater

42: Resistive heating element

44: Shell, heater shell

46: Insulation material

48: scheduled algorithm

50: Power pin

52: Seal

60: Power switch

62: Controller

64: Mass flow limit table

66: Power output limiting device

100: Method for predicting the temperature of at least one location in a fluid flow system with a heater in a heating system for heating fluid

110~140,210~240: steps

200: Another method for predicting the outlet temperature after each of the multiple resistive heating elements in a heater system that is placed in a fluid flow system for heating fluid

In order to better understand the content of this disclosure, various forms will be described with examples. Refer to the accompanying drawings, in which: Fig. 1 is a schematic diagram of a diesel engine and exhaust gas aftertreatment system applying the principles of the present disclosure; Fig. 2 is a cross-sectional view of a tubular heater structure according to the prior art; 3 is a schematic diagram showing a series of components in a fluid flow system according to the teachings of the present disclosure; FIG. 4 is a diagram showing at least one position in a fluid flow system predicted to have a heater according to the teachings of the present disclosure The flow chart of the temperature method; FIG. 5 is a diagram showing the outlet temperature of each of a plurality of resistive heating elements placed in a heater system in a fluid flow system predicted according to the teachings of the present disclosure The flow chart of the method; and FIG. 6 is a block diagram of a heater control module constructed according to the teachings of the present disclosure.

The drawings described in this article are for illustration purposes only, and are not intended to limit the scope of the disclosure in any way.

Detailed description of the preferred embodiment

The following description is merely illustrative in nature, and is in no way intended to limit the content of the disclosure, its application, or use. It should also be understood that the steps in a method can be executed in a different order without changing the principle of the content of the disclosure.

Referring to FIG. 1, an exemplary engine system 10 generally includes a diesel engine 12, an alternator 14 (or in some applications, a generator), a turbocharger 16 and an exhaust aftertreatment system 18. The exhaust gas aftertreatment system 18 is arranged downstream of the turbocharger 16 to treat the exhaust gas from the diesel engine 12 before the exhaust gas is released to the atmosphere. The exhaust aftertreatment system 18 may include one or more additional components, devices, or systems that are operable to further process the exhaust fluid stream to achieve a desired result. Example in Figure 1 The exhaust gas aftertreatment system 18 includes a heating system 20, a diesel oxidation catalyst (DOC) 22, a diesel particulate filter (DPF) 24, and a selective catalytic reduction device (SCR) 26. The exhaust gas aftertreatment system 18 includes: an upstream exhaust pipe 32 which receives a heater assembly 28 therein; an intermediate exhaust pipe 34 in which a DOC 22 and a DPF 24 are provided; and a downstream exhaust pipe 36 , In which SCR 26 is placed.

It should be understood that the engine system 10 shown and described herein is only exemplary, and therefore may include _{other components such as a NO x} absorber or an ammonia oxidation catalyst (plus others), and may not use such as DOC 22, DPF 24, and SCR. The other components. In addition, although a diesel engine 12 is shown, it should be understood that the teachings of the present disclosure are also applicable to gasoline engines and other fluid flow applications. Therefore, the application of diesel engines should not be interpreted as limiting the scope of this disclosure. These changes should be interpreted as belonging to the scope of this disclosure.

The heating system 20 includes a heater assembly 28 arranged upstream of the DOC 22 and a heater control module 30 for controlling the operation of the heater assembly 28. The heater assembly 28 may include one or more electric heaters, where each electric heater includes at least one resistive heating element. The heater assembly 28 is placed in a discharge fluid flow path to heat the fluid flow during operation. The heater control module 30 typically includes a control device adapted to receive input from the heater assembly 28. Examples of controlling the operation of the heater assembly 28 may include turning the heater assembly on and off, modulating the power of the heater assembly 28 as a single unit, and/or modulating to individual sub-components (such as, If available, the power of individual or group resistive heating elements), and combinations thereof.

In one form, the heater control module 30 includes a control device. The control device communicates with at least one electric heater of the heater assembly 28. The control device is adapted to receive at least one input, including but not limited to the discharge fluid flow, the mass velocity of the discharge fluid flow, the flow temperature upstream of the at least one electric heater, the flow temperature downstream of the at least one electric heater, and input to at least The power of an electric heater, the parameters derived from the physical characteristics of the heating system, and their combinations. The at least one electric heater may be any heater suitable for heating the discharged fluid. Example electric heaters include, but are not limited to, ribbon heaters, bare-wire resistive heating elements, cable heaters, cartridge heaters, layered heaters, electric heating wires Heaters, tubular heaters and combinations thereof. Taking examples to illustrate, physical characteristics can include resistance wire diameter, MgO (insulation) thickness, shell thickness, conductivity, specific heat and density of the material of construction, heat transfer coefficient and emissivity of heaters and fluid pipes, plus other geometries and applications Related information.

The system of Fig. 1 includes a DOC 22 arranged downstream of the heater assembly 28. The DOC 22 acts as a catalyst to oxidize carbon monoxide and any unburned hydrocarbons in the exhaust gas. In addition, the DOC 22 converts nitrogen monoxide (NO) into nitrogen dioxide (NO ₂ ). The DPF 24 is arranged downstream of the DOC 22 to assist in the removal of diesel particulate matter (PM) or soot from the exhaust gas. The SCR 26 is arranged downstream of the DPF 24 and uses a catalyst to convert nitrogen oxides (NOx) into nitrogen (N ₂ ) and water. The urea aqueous solution injector 27 is arranged downstream of the DPF 24 and upstream of the SCR 26 for injecting the urea aqueous solution into the exhaust gas stream. When the aqueous urea solution is used as the reducing agent in SCR 26, NOx is reduced to N ₂ , H ₂ O, and CO ₂ .

In one form of this disclosure, the data from the engine system 10 described above is used in a mathematical model to predict various temperatures without using physical sensors, including heater temperature, exhaust gas inlet temperature, and exhaust gas outlet temperature, plus other. These models have been developed for both transient and non-transient systems, and are suitable for a variety of heater types and fluid flow applications. Therefore, the various forms of tubular heaters and engine exhaust provided in this article should not be construed as limiting the scope of the disclosure. In addition, the specific reference to the temperature of the "heater housing" is only an example, and the calculated temperature can be for belt heaters, bare wire resistive heating elements, cable heaters, cartridge heaters, and layered heaters. , Any component of electric heating wire heater or tubular heater plus any other type of heater. "Layered heater" has been previously defined in US Patent No. 7,196,295, which is jointly assigned with this application and its contents are fully incorporated herein by reference.

Referring to FIG. 2, a tubular heater is used as an example heater type used in the heater assembly 28, and is shown and generally indicated by the reference numeral 40. The tubular heater 40 includes a resistive heating element 42 disposed in a housing 44, and an insulating material 46 disposed therebetween, such as, by way of example, dense magnesium oxide (MgO). The tubular heater 40 may also include a power pin 50 and a sealing element 52.

The present disclosure provides a control system and a method for controlling an electric heater. The electric heater usually includes input (such as mass flow or flow rate, flow temperature upstream or downstream of the heater, heater power input, and auto Any parameter derived from the physical characteristics of the system) is a device/equipment to then modulate the power to the heater based on these inputs. In order to calculate the value of the system depending on a set of known variables, various methods are disclosed in this article. It should be understood that these equations are only illustrative, and should not be construed as limiting the scope of the disclosure.

For example, in order to calculate the temperature of the housing 44 without using a physical sensor in applications such as the diesel exhaust described above, for various heater configurations, the mass flow rate, the inlet temperature and the power sent to the heater 40 are used. , Together with the heat transfer equation. In one form, the following equation 1 is used to calculate the temperature (T _s ) of the housing 44:

Among them: Ac = heater cross-sectional area; As = housing area; C = based on Reynolds number (Re) and the first constant shown in Table 1 below; C ₂ = deviation based on the number of heater elements; D = heater Element diameter; K = thermal conductivity of air; kW = total heater power; M _fuel = mass flow rate of fuel; M _inlet = inlet mass air flow (MAF) rate; m = display based on Reynolds number (Re) and below The second constant in Table 1; P _r = the Bront number of air obtained at the gas temperature; Pr _s = the Bront number of air obtained at the case temperature; S _T = the lateral distance between components; T _outlet = heater outlet temperature; and μ = air viscosity.

Re _D,max = Reynolds number for a given diameter and maximum speed; N _L = number of elements; and C ₂ = When evaluating element 1, use N _L =1; when evaluating 6 elements, N _L It starts at 0.7 and increases to 0.92 as each component is analyzed.

In addition, in this equation 1, there is no radiation effect yet, but it can be combined while staying within the scope of this disclosure.

In addition to the heater housing 44 temperature, the outlet temperature behind each element in the fluid flow (see Figure 3) can be calculated/modeled, thus reducing the need for additional temperature sensors. In one form, the outlet temperature is calculated according to Equation 2 below:

=質量流率；T_出口,1=在加熱元件1後之出口溫度；T_入口,1=加熱元件1之入口溫度；及T_s=外殼溫度。 Among them: A _s = surface area of the shell; C _p = specific heat of air under constant pressure; h = convective heat transfer coefficient;

= Mass flow rate; T _{outlet, 1} = outlet temperature after heating element 1; T _{inlet, 1} = inlet temperature of heating element 1; and T _s = shell temperature.

Therefore, using Equation 2, it is possible to predict temperature throughout the fluid flow system without using physical sensors. As a further advantage, due to the lag time associated with the physical sensor, and especially in transient systems, using the equation as set forth in this article results in a faster response time. Better accuracy and faster response time also allow the use of heaters operating at higher temperatures, thus providing improved performance and reducing safety margins. In addition, the failure mode of the physical sensor is removed from this disclosure.

Since Equation 1 is for steady state, the following equation is used for virtual sensing as disclosed in this article, that is, Equation 3:

=質量流率；Pr=在氣體溫度下取得的空氣之卜朗特數；Pr_s=在外殼溫度下取得的空氣之卜朗特數；S_T=元件之間的橫向距離；T_入口=加熱器入口溫度；T_出口=加熱器出口溫度；及μ=空氣之黏度。 Among them: Ac = heater cross-sectional area; As = housing area; C = constant based on Reynolds number (Re) and Table 1; C ₂ = deviation based on the number of heater elements; C _p = air under constant pressure The specific heat; D = heater element diameter; K = thermal conductivity of air; M _fuel = mass flow rate of fuel; M _inlet = inlet mass air flow (MAF) rate; m = based on Reynolds number (Re) and Table 1 The constant

= Mass flow rate; Pr=Brand number of air obtained at gas temperature; Pr _s =Brand number of air obtained at shell temperature; S _T = lateral distance between elements; T _inlet = heating The inlet temperature of the _{heater; T outlet} = the heater outlet temperature; and μ = the viscosity of the air.

Generally, in order not to be limited to the specific equations disclosed in this article, T _{s is} determined by the input equation set using the set point, mass flow, and inlet temperature to calculate the system temperature.

The present disclosure further provides predictive/proactive control of the heater 40. For example, system data such as torque demand, pedal position, and increased manifold absolute pressure (MAP)/boost pressure/engine timing can be converted to mass flow rate, and then the mass flow rate can be provided to the control system to Determine the required heater power before power is needed, instead of relying on the delayed response to the physical sensor.

A variation of the content of this disclosure considers the radiation effect according to Equation 4: Q=ε. σ. v _f ( T _h + T _se ) Equation 4

Among them: Q = radiation density; T _h = absolute heater temperature; T _se = absolute sensor temperature; V _f = viewing angle factor (the part of the heater radiation that strikes the sensor); ε = emissivity; and σ = Stephen-Bozeman constant.

In addition, the heater can be fully mathematically quantified so that the system frequency response of all materials including the heater can be determined from the mass air flow (MAF) rate, heater inlet temperature, and applied power. The frequency response of the heater to changes in the engine and exhaust conditions or general system damage can be reduced, allowing the heater to have a faster feedback response. This then improves the control of the heater element temperature, which allows the heater to have a higher watt density (watts per unit length, watts per unit area, or watts per unit volume) as temperature fluctuations are reduced. And better durability. The system representation can be simplified into a form that the control microprocessor can use with reduced effort. In addition, the content of this disclosure can simplify the relatively complex mathematical process into a tabular form, so as to reduce the processing capacity and the expected state of the definition. It should be understood that a variety of methods for obtaining mass flow rate can be used, such as, to illustrate, MAP and combined inlet air mass flow and fuel consumption. Therefore, as used herein, the term "mass flow" should be interpreted to include these and other methods of obtaining mass air flow.

Generally, the present disclosure takes input from various devices (such as, by way of example, engine, exhaust device, electric power, and heater), executes various algorithms, and then generates output, such as actual power consumption, exhaust temperature, Heater temperature, diagnosis and emission mass flow. Engine inputs/parameters may include exhaust temperature and exhaust flow; and heater inputs/parameters may include heater power, geometric dimensions and coefficients. The system model may include a heater model, wire temperature and housing temperature, and at least one control algorithm. These outputs can then include exhaust temperature, exhaust flow, and diagnostics.

In yet another form, the virtual sensing system is used in a diagnostic mode to compare a response of the heater 40 with a known applied power to determine whether the total exhaust aftertreatment system 18 is degrading, has reduced efficiency, or is in Whether there are defects in the exhaust aftertreatment system 18. In addition, the virtual sensing system may allow removal of the catalyst inlet temperature sensor, thereby reducing the cost and complexity of the total exhaust gas aftertreatment system 18. If the catalyst inlet temperature sensor is kept in the exhaust aftertreatment system 18, its output can be compared with the calculated/predicted heater outlet temperature provided by the virtual sensor system, and any mismatch between them can trigger engine control One of the diagnostic trouble codes in the unit (ECU). In addition, the virtual sensor system of the present disclosure can be integrated with a model-based design (for example, Simulink) to improve instantaneous performance and allow better characterization of the heater system. In addition, a model-based design can adjust the parameters/characterization of the virtual sensor system based on a specific application different from the diesel exhaust application as used herein.

The use of the virtual sensor system further reduces the uncertainty of knowing the temperature of the actual resistive element (for example, wires), and allows for reduced safety margins, increased watt density, and smaller heater surface area, thus leading to more Efficient and less costly heater.

The control system as disclosed herein can also control the power to the heater by calculating or virtual temperature by one of the resistive heating elements (such as a resistance wire). Reference is made to the application in the same application titled "Advanced Two-Wire Heater System for Transient Systems" which has been incorporated herein by reference. In some applications such as tubular heaters, the control of the temperature of the virtual wire overcomes the thermal inertia of the insulation and the housing. This results in less temperature changes on the wires, which improves reliability. This method also reduces the cyclic load on the power supply, thereby allowing more balanced power transfer and less strain on the power supply.

The present disclosure further provides an engine system 10, which includes a control system for controlling the heating system of the exhaust system as described above. The control device is adapted to receive engine input selected from the group consisting of engine parameters, exhaust parameters, power output, and heater parameters, and the device is operable to Generate output selected from the group consisting of power consumption, exhaust temperature, heater temperature, diagnosis, emission mass flow rate, and combinations thereof. The control system is further operable to diagnose degraded engine system components. In this example, the control system communicates with an engine control unit, and is adapted to trigger a diagnostic trouble code when a determined parameter does not match a preset parameter.

Referring to FIG. 4, the present disclosure further includes a method 100 for predicting the temperature of at least one location in a fluid flow system having a heater disposed in a heating system for heating fluid. The method includes obtaining the mass flow rate 110 of the fluid flow of the fluid flow system, obtaining at least one of the fluid outlet temperature and the fluid inlet temperature of the heater 120, obtaining the power provided to the heater 130, and one based on the fluid flow system The model and the obtained mass flow rate and fluid outlet and inlet temperature calculate the temperature 140 at at least one location. The at least one position may be on a heating element of at least one electric heater of the heating assembly. The model may include the temperature prediction model as previously described above. This process can be further integrated with a model-based design.

Referring to FIG. 5, the present disclosure further provides another method 200 for predicting the outlet temperature of each of a plurality of resistive heating elements in a heater system for heating fluid disposed in a fluid flow system. The method includes obtaining the mass flow rate 210 of the fluid flow of the fluid flow system, obtaining the fluid inlet temperature 220 to at least one resistive heating element, obtaining the power provided to each resistive heating element and the input of the fluid flow system to each resistance The characteristic 230 of the power of the sexual heating element related to the power transferred to the fluid flow, and the outlet temperature 240 is calculated based on a model of the fluid flow system.

As used herein, the term "model" should be interpreted as meaning a program or a system of equations, a table of values representing the values of parameters under various operating conditions, an algorithm, a computer program, or a computer instruction set , A signal conditioning device or any other device that modifies controlled variables (for example, the power to the heater) based on prediction/planning/future conditions, where the prediction/planning is based on a combination of a priori and field measurements.

Therefore, many different forms of heaters, sensors, and control systems have been disclosed in this article. And related devices and methods for use in fluid flow systems. Many of the different forms can be combined with each other, and can also include additional features specific to the data, equations, and combinations as described herein. These changes should be interpreted as belonging to the scope of this disclosure.

Referring to FIG. 6, in conjunction with FIG. 1, as previously indicated, the heater control module 30 can be configured to control the operation of the heater assembly 28 and adjust the power of the heater assembly 28. In this embodiment, the heater control module 30 can be integrated or communicated with the engine 12 to allow the exhaust gas in the exhaust gas aftertreatment system 18 to be processed without compromising or having less interference with the fuel efficiency.

In the prior art heating system used in the exhaust system, the heater can be activated based only on the condition of the exhaust system (such as the temperature of the exhaust gas) without considering the condition of the engine and the battery. This control can compromise fuel efficiency. For example, when the vehicle is operated in a charge exhaustion or EV mode where the operation of the vehicle depends on energy from the battery pack, actuating the heater in this state causes an increased demand for power. If the state of the charged battery is low, this increased demand for power can switch the vehicle from the charge depletion mode to the engine operation mode, thereby undesirably increasing fuel consumption.

Therefore, the heater control module 30 for the heating system 20 of the exhaust gas aftertreatment system 18 can be configured to control the heater assembly in a way that reduces emissions from the exhaust gas aftertreatment system 18 while considering fuel efficiency. 28 One or more electric heaters. One or more electric heaters of the heater assembly 28 are arranged in a discharge fluid flow path. The heater control module 30 includes a control device 31, which is configured to receive at least one input about the condition of the engine, battery, alternator, heater, exhaust gas aftertreatment system 18 and subsequent processing components along with the exhaust gas The temperature of the exhaust fluid flow path of the aftertreatment system 18 is adjusted to the power of the heater assembly 28 accordingly.

When at least one input is an engine-related condition, the engine-related condition can be represented by a predetermined or desired temperature distribution. The at least one input may also be related to the condition of the battery, the alternator, the heater, and the post-processing components of the exhaust gas after-treatment system 18. Therefore, the at least one input can be selected from the group consisting of: temperature readings along the discharge fluid flow path, alternator power, alternator current, alternator voltage, battery power, battery current, battery Voltage, battery state of charge (SOC), intake air throttle (IAT) and exhaust throttle (EAT) configuration, exhaust gas recirculation (EGR), mass flow rate of exhaust fluid flow, NH ₃ escape, Temperature coefficient of resistance (TCR) characteristics of electric heaters, alternator speed, engine speed, aging status of post-processing components, engine aging status, aging degradation characteristics, dosing rate of diesel exhaust fluid (DEF), DEF _{Temperature, NH 3} storage status of the aftertreatment system, injection timing delay, cylinder shut-off, variable valve control, turbocharger bypass, intake air preheating, secondary post injection in the cylinder, ambient temperature and combinations thereof. Based on at least one input, the control device 31 is operable to modulate and adjust the power to the heater assembly 28 continuously or at a predetermined interval. Depending on the at least one input, different power/heating outputs are provided by the heater assembly 28 to heat the exhaust gas in the exhaust gas aftertreatment system 18.

Among multiple inputs, the aging state of the component refers to the time and temperature history of the component. The IAT-EAT distribution may include temperature-mass flow distribution, temperature-engine speed distribution, temperature-engine speed distribution, temperature-load distribution, or temperature-engine condition distribution. All these distributions have different temperature targets based on engine conditions. One or more of the electric heaters of the heater assembly 28 may include one or more resistive elements. The control device 31 can adjust the power to the heater assembly 28 based on the calculated temperature of the resistive element.

As an example, when at least one input includes temperature readings along the discharge fluid flow path, the temperature readings are relative to a threshold value to adjust or modify the output of the heater assembly 28 so that the heater assembly Cheng 28 provides different power outputs below and above the threshold. In one example, the temperature readings may be the inlet temperature of the selective catalytic reduction (SCR) device 26. When the SCR inlet temperature is lower than the threshold, the heater assembly 28 provides a higher power output. When the SCR inlet temperature is higher than the threshold, the heater assembly 28 provides a lower power output. Higher power output includes an increase in the magnitude and/or rate of power increase.

The control device 31 may include a power switch 60, a controller 62, a mass flow limit table 64, and a power output limit device 66. The controller 62 can be a PID controller, a predictive feedback controller, a model-based controller, or any controller known in the art that can control heater power output. 制器。 Controller.

When at least one input such as a temperature reading is higher than a threshold value, the controller 62 can be used to control the heater power based on the temperature reading. However, when the temperature reading is below the threshold and higher heater power output or rapid heating is required, the control device 31 can bypass or bypass the controller 62 and use the mass flow limit table 64 and the power output limit device 66 to provide heating器 Power. The at least one input is constantly or periodically monitored. When the at least one input has increased to reach the threshold, the control of the heater assembly 28 can be switched to PID control with a limit. Alternatively, the control of the heater assembly 28 may be based on a predetermined algorithm 48.

Improved NOx conversion during cold exhaust conditions can achieve the best fuel savings. When the exhaust device is cold, faster heating during cold exhaust conditions can improve the NOx conversion, thereby allowing the engine to run at a relatively lower temperature when the exhaust device later becomes warmer to save fuel. Faster heating during cold exhaust conditions can be achieved by increasing the power sent to the heater to provide more heat. Advance fuel injection timing can also improve fuel economy. Therefore, the engine calibration can be modified to supply additional heat along with the operation of the heater assembly 28 when more heat is required.

The fuel used during cold exhaust conditions is typically a small part of the total fuel use. By using more fuel than is typically required when the exhaust gas temperature is lower, faster heating can be achieved, thereby achieving better NOx conversion. Better NOx conversion during cold exhaust conditions achieves reduced NOx conversion when the exhaust device later becomes warmer. Therefore, when the exhaust device is warmer, the temperature for NOx conversion can be lowered to reduce fuel consumption. When the exhaust device is warm, the heater power can also be minimized.

When additional fuel is used to achieve rapid heating during cold exhaust conditions, fuel is saved during subsequent warmer exhaust conditions when the engine is running at a relatively low temperature. As a result, the additional fuel used during cold exhaust conditions is compensated by lowering the temperature (and therefore fuel consumption) during subsequent warming exhaust conditions. Although this strategy will increase NOx emissions during subsequent warmer exhaust conditions, the amount of NOx emissions will still be within the control range according to government regulations. The effect of this fuel saving strategy It can be further enhanced by combining engine heating for rapid heating (such as delayed timing for fuel injection), multiple injections, and injection pressures.

In order to reduce fuel consumption during low load operation, a condition-based set point is used instead of a single fixed set point to more closely match the desired temperature distribution based on engine conditions. In other words, the desired set point varies with engine conditions.

In another example, the at least one input may include battery current or current state of charge. In this case, when the state of charge of the battery is below a threshold, the heater power is limited. Therefore, the heater assembly 28 can be controlled to be restricted based on engine/alternator speed or based on changes in voltage over time.

When too much ammonia is injected into the SCR device 26 or when the SCR temperature increases and the NH3 storage capacity decreases, NH3 escape occurs. When at least one input includes NH3 escape, the heater power is lower when NH3 escape exceeds a threshold value, and is higher when NH3 escape is below the threshold value.

The power switch 60 of the control device 31 can be used to control the power to the heater assembly 28. The power switch 60 allows pulsed current/power to be supplied to the heater assembly 28. The power is pulsed to control the current supply to the heater assembly 28. When the current is pulsed, the voltage and average current are used to calculate the power to the heater assembly 28. By using pulsed power together with power measurement, combined with information about the emission mass flow, the mass flow limit table 64 and the algorithm 48 can be used to protect the heater assembly 28 and make the heater assembly 28 smaller.

In summary, the heater assembly 28 is controlled to provide heating for the exhaust gas in the exhaust aftertreatment system 18 in consideration of fuel efficiency. Therefore, the heater assembly 28 is operated in a way that provides more precise thermal control to meet emission requirements when preserving fuel via optimization. The heater assembly 28 may be controlled differently based on whether at least one input is below or above a threshold value, or may be controlled differently in multiple heating modes. The at least one input includes parameters related to the condition of the engine, the condition of the battery, the condition of the alternator, the condition of the aftertreatment component and the condition of the heater, and the temperature of the exhaust gas aftertreatment system. Multiple heating The mode is based on the condition of the engine, battery, alternator, aftertreatment components, heater, and the temperature of the exhaust aftertreatment system.

The heater power is limited based on the power measurement and based on the duty cycle to reduce fuel consumption. By limiting the heater power, it is avoided that the exhaust gas is heated to a single set point, especially during periods of generally lower engine speed and load. By limiting the heater power, switching the vehicle from the EV mode to the engine operation mode (in which the alternator recharges the battery) is avoided. The power limit varies with the mass flow (or engine-based mapping). The heater assembly 28 can also be used to manage NH3 storage, thereby controlling NH3 escape. The temperature of the heater assembly 28 is controlled based on power measurements (in the case of engines, alternators, batteries, etc.). In addition, in order to preserve fuel, the temperature set point changes under different engine conditions. As a result, fuel can be used more efficiently, while NOx emissions can be controlled within a range to comply with government regulations.

The description of the content of the disclosure is merely illustrative in nature, and therefore, changes that do not deviate from the essence of the content of the disclosure are intended to be within the scope of the content of the disclosure. Such changes should not be regarded as departing from the spirit and scope of the content of this disclosure.

10: Engine system

12: Diesel engine

14: Alternator

16: turbocharger

18: Exhaust aftertreatment system

20: heating system

22: Diesel oxidation catalyst (DOC)

24: Diesel Particulate Filter (DPF)

26: Selective Catalytic Reduction (SCR)

27: Urea aqueous solution injector

28: heater assembly

30: Heater control module

32: Upstream exhaust pipe

34: Intermediate exhaust pipe

36: Downstream exhaust pipe

Claims (15)

A control system is a heating system used in an exhaust system. The control system includes: at least one electric heater arranged in an exhaust fluid flow path; and a control device configured to operate the at least one electric heater The heater is adapted to receive at least one input, wherein the at least one input relates to at least one of an engine condition or a desired temperature distribution, and the at least one input includes temperature readings along the discharge fluid flow path, communication Generator power, alternator current, alternator voltage, battery power, battery current, battery voltage, battery state of charge, a desired engine condition, intake air throttle (IAT) and exhaust throttle ( EAT) configuration, exhaust gas recirculation (EGR), mass flow rate of an exhaust fluid stream, NH ₃ escape, temperature coefficient of resistance (TCR) characteristics of the at least one electric heater, alternator speed, engine speed, a rear The aging state of the processing components, the aging state of the engine, the aging degradation characteristics, a dosing rate of a diesel exhaust fluid (DEF), a temperature of the DEF, the NH ₃ storage status of the aftertreatment system, the injection timing delay, the cylinder shut-off Shut off, variable valve manipulation, turbocharger bypass, intake preheating, in-cylinder secondary injection, ambient temperature, or a combination thereof, and wherein the control device is operable to be based on the at least one input and a predetermined One of the right control and a mass flow limit table adjusts the power sent to the at least one electric heater, so that the at least one electric heater provides a different heating output as the at least one input changes, And the at least one electric heater provides a continuously variable heating output during the operation of the exhaust system, and wherein the control device is operable to be based on a value between a value of the at least one input and a threshold value Compare to select one of the predefined control and the mass flow restriction table. The control system according to claim 1, wherein the at least one input includes the temperature reading along the discharge fluid flow path, and the control device is configured to compare the temperature reading with the temporary Limit, and when the temperature reading is higher than the threshold, operate the at least one electric heater based on the temperature reading and the predefined control, and when the temperature reading is lower than the threshold, based on the quality At least one of a flow restriction table and a power output restriction device operates the at least one electric heater. The control system of claim 2, wherein the temperature reading includes an SCR inlet temperature, and the at least one electric heater is operated to provide a higher temperature than at the SCR inlet when the SCR inlet temperature is lower than the threshold A heating output that is still higher at the threshold. The control system according to claim 3, wherein the control device provides at least one of a magnitude and a rate of power increase to the at least one electric heater to provide the higher heating output. The control system according to claim 2, wherein the predefined control includes at least one of a proportional integral derivative (PID) control, a predictive feedback control, and a model-based control. The control system according to claim 1, wherein the at least one input includes a temperature distribution based on an engine condition, which includes a temperature-mass flow distribution, a temperature-engine speed distribution, a temperature-engine speed distribution, and a temperature -Load distribution or a temperature-engine condition distribution. The control system according to claim 6, wherein the control device is configured to operate the at least one electric heater based on at least one of a mass flow limit table and a power output limit, and the power output limit is based on the At least one input and a threshold value associated with the at least one input. The control system according to claim 1, wherein the at least one input includes the battery state of charge, and the control device is configured to limit the supply to the at least one electric heater when the battery state of charge is lower than a threshold The power of the device. The control system according to claim 1, wherein the control device is configured to provide power to the at least one electric heater in a pulsed manner to control current supply. The control system according to claim 1, wherein the at least one input includes the NH ₃ escape, and the control device is configured to operate the at least one electric heater to provide when the NH ₃ escape exceeds a threshold The heating output is lower than when the NH ₃ escape is lower than a threshold value. A method for controlling the heating of an exhaust system, comprising: obtaining at least one input related to at least one of an engine condition or a desired temperature distribution; and according to a predefined control and a mass flow limit table One of the choices is to modulate the power sent to at least one electric heater arranged in an exhaust fluid flow path of an exhaust system based on the at least one input and an associated threshold so that the at least one The electric heater provides a continuously variable heating output during the operation of the exhaust system, wherein the selection of one of the predefined control and the mass flow limit table is based on a value and a threshold of the at least one input A comparison between values; wherein the at least one input relates to at least one of an engine condition or a desired temperature distribution, and the at least one input includes temperature readings along the exhaust fluid flow path, alternator power , Alternator current, alternator voltage, battery power, battery current, battery voltage, battery state of charge, a desired engine condition, intake air throttle (IAT) and exhaust throttle (EAT) configuration Type, exhaust gas recirculation (EGR), mass flow rate of an exhaust fluid stream, NH ₃ escape, temperature coefficient of resistance (TCR) characteristics of the at least one electric heater, alternator speed, engine speed, a combination of post-processing components Aging state, engine aging state, aging degradation characteristics, a dosing rate of a diesel exhaust fluid (DEF), a temperature of the DEF, NH ₃ storage status of the aftertreatment system, injection timing delay, cylinder shutdown, Variable valve operation, turbocharger bypass, intake air preheating, in-cylinder post injection, ambient temperature, or a combination thereof. The method of claim 11, wherein the at least one input includes the temperature reading along the discharge fluid flow path, and the method further comprises: comparing the temperature reading with the threshold; when the temperature reading is higher than the When the threshold is reached, operate the at least one electric heater based on the temperature reading and a predetermined control; and When the temperature reading is lower than the threshold value, the at least one electric heater is operated based on at least one of the mass flow limit table and a power output limit device. The method according to claim 12, wherein the predefined control includes at least one of proportional integral derivative (PID) control, predictive feedback control, and a model-based control. The method according to claim 11, further comprising providing power to the at least one electric heater in a pulsed manner to control current supply. The method according to claim 14, further comprising: calculating the power supplied to the at least one electric heater based on a voltage and an average current supplied to the at least one electric heater; and based on the calculated power and the at least one electric heater An input to control the power sent to the at least one electric heater.

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