KR20180065374A - Device and method to protect the catalyst for the mild hybrid electric vehicle - Google Patents

Abstract

Disclosed are an apparatus and a method for protecting a catalyst for a mild hybrid electric vehicle, capable of preventing the catalyst from being deteriorated and damaged by high temperature exhaust gas. According to an aspect of the present invention, the apparatus of protecting the catalyst includes an exhaust gas temperature monitoring unit, a comparison unit, and a control unit. The exhaust gas temperature monitoring unit estimates or detects the temperature of exhaust gas flowing along an engine exhaust line and transmits, to the comparison unit, information on the estimated or detected temperature. The comparison unit receives information on the estimated or detected temperature from the exhaust gas temperature monitoring unit and compares the estimated or detected temperature with a threshold temperature serving as the criterion of the deterioration of the catalyst. The control unit restricts an engine output to the catalyst from being deteriorated in response to a control commencement signal output from the comparison unit when the temperature of the exhaust gas is equal to or greater than the criterion of the deterioration of the catalyst. In addition, the control unit increases the output of the motor by an insufficient engine output, thereby compensating for the insufficient engine output.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a catalyst protection device for a mild hybrid vehicle,

The present invention relates to an apparatus and a method for protecting a catalyst of a vehicle, and more particularly, to an apparatus and a method for protecting a catalyst in a mild hybrid vehicle in which the motor assists the engine output.

Recently, due to the acceleration of environmental pollution, regulations on exhaust gas, which has a great influence on air pollution, are increasingly being tightened in the automobile industry.

In each country, automakers are forced to reduce emissions by strengthening various regulations. Especially in Europe, when the CO2 emission exceeds the standard value (95 g / km), a method of imposing a penalty proportional to the excess amount, The government has strongly anticipated that the government will strongly regulate the government.

However, for vehicles equipped with conventional powertrains based on gasoline or diesel engines, it is not easy to improve exhaust emissions to meet the enhanced CO2 regulations in a limited amount of time.

One of the ways to meet exhaust emission regulations is the use of a DOC (Diesel Oxidation Catalyst). The catalytic purifier is a technology for removing hydrocarbons, carbon monoxide, and the like contained in the exhaust gas by using oxygen with catalytic effect such as platinum (Pt) and palladium (Pd).

In the case of a catalyst, which is a core component of a catalyst-type exhaust gas purifying apparatus, deterioration may occur due to high-temperature exhaust heat. If deterioration occurs, the catalyst itself may be damaged and the function may be lost. Is necessary.

In this regard, it is known that the fuel injection amount is injected richer than the stoichiometric air-fuel ratio, thereby lowering the exhaust gas temperature. Therefore, as a technique for preventing deterioration of the catalyst, a technology of lowering the exhaust gas temperature by increasing the fuel injection amount when the catalyst approaches the deterioration temperature Has been used. However, such prior art has a problem that the fuel consumption is deteriorated because the fuel must be separately injected in order to prevent deterioration of the catalyst.

Korean Published Patent Application No. 2008-0068126 (published on July 22, 2008)

SUMMARY OF THE INVENTION It is an object of the present invention to provide an exhaust gas purifying apparatus and an exhaust gas purifying apparatus in which when the catalyst of the exhaust gas purifying apparatus becomes close to the deterioration temperature, the output of the engine is limited to lower the exhaust gas temperature, And to provide a catalyst protecting apparatus and method for a mild hybrid vehicle which can effectively prevent the catalyst from deteriorating due to high-temperature exhaust heat while improving fuel efficiency deterioration by reducing fuel consumption for preventing deterioration of high temperature of the catalyst.

According to an aspect of the present invention,

An apparatus for preventing catalyst deterioration of an exhaust gas purifying apparatus in a mild hybrid vehicle in which the motor assists the engine output,

An exhaust gas temperature monitoring unit for estimating or detecting the temperature of the exhaust gas flowing along the engine exhaust line and transmitting the estimated or detected temperature information to the comparison determination unit;

A comparison determination unit for receiving the temperature information estimated or detected from the exhaust gas temperature monitoring unit and comparing the temperature information with the deterioration reference threshold temperature of the catalyst; And

When the temperature of the exhaust gas is equal to or higher than the deterioration reference threshold temperature, the engine output is limited in order to prevent deterioration of the catalyst according to the control start signal output by the comparison and determination unit, And a control unit for performing control to compensate for a lack of engine output. The present invention also provides a catalyst protecting apparatus for a mild hybrid vehicle.

Here, the exhaust gas temperature monitoring unit preferably estimates an exhaust gas temperature corresponding to a current operating condition of the vehicle utilizing a map including information on the relationship between the driving condition of the vehicle and the exhaust gas temperature, And outputting the information to the comparison determination unit as current exhaust gas temperature information.

As another example, the exhaust gas temperature monitoring unit may include a temperature detection unit that is provided on the upstream side or the downstream side of the purifying device installed in the engine exhaust line on the basis of the flow direction of the exhaust gas to directly detect the temperature of the exhaust gas flowing along the exhaust line And outputting the exhaust gas temperature information obtained through the temperature detection sensor to the comparison determination unit.

Further, the control unit calculates an engine output shortage from a difference value between the engine target output (demand output) set in accordance with the accelerator pedal operation and the engine output limited for preventing deterioration of the catalyst, A motor output value calculating unit for calculating a motor output value corresponding to the motor output value and controlling an output of the motor based on the determined control value, And a motor output control unit for compensating the motor output.

In order to prevent deterioration of the catalyst, the engine output restriction can be implemented by controlling the air amount adjusting actuator and the fuel injection injector so that the actual air-fuel ratio (mixing ratio of air and fuel) does not exceed the stoichiometric air-fuel ratio (14.7: 1).

According to another aspect of the present invention as a solution to the problem,

A method for preventing catalyst deterioration of an exhaust gas purifying apparatus in a mild hybrid vehicle in which the motor assists the engine output,

An exhaust gas temperature monitoring step (S100) for estimating or detecting the temperature of the exhaust gas flowing along the engine exhaust line;

A comparison determination step (S200) of comparing the temperature information estimated or detected in the exhaust gas temperature monitoring step with the deterioration reference critical temperature of the catalyst (Catalyst); And

An output limiting step (S300) of limiting an engine output to prevent deterioration of the catalyst when the exhaust gas temperature is equal to or higher than the degradation reference threshold temperature as a result of the comparison;

And an output compensating step (S400) of compensating for a lacking engine output by increasing the output of the motor by an insufficiency of the engine output (S400).

In step S100, information necessary for grasping the driving condition of the vehicle is acquired from the sensors of each part of the vehicle, and the driving condition of the current vehicle determined using the map including the relationship between the driving condition and the exhaust gas temperature It is possible to estimate the exhaust gas temperature corresponding to the exhaust gas temperature.

Alternatively, in step S100, the temperature of the exhaust gas flowing along the exhaust line may be directly detected using a temperature detection sensor.

In step S300, the engine output can be limited by controlling the air amount adjusting actuator and the fuel injection injector such that the air-fuel ratio (mixing ratio of air and fuel) does not exceed the stoichiometric air-fuel ratio (14.7: 1).

Also, in step S400, the engine output shortage is calculated from the difference between the engine target output (demand output) set according to the accelerator pedal operation and the engine output limited for preventing deterioration of the catalyst, The motor output value is calculated as a motor output value, the motor control value corresponding to the motor output value is determined, and the output of the motor is controlled based on the determined control value to compensate the engine output that is insufficient by the engine output shortage have.

According to the catalyst protecting apparatus and method of the mild hybrid vehicle according to the present invention, when the catalyst of the exhaust gas purifying apparatus becomes close to the deterioration temperature, the output of the engine is limited to lower the exhaust gas temperature, Is compensated by the motor. As a result, it is possible to reduce the amount of fuel consumed for preventing deterioration of the catalyst, so that the effect of improving the fuel economy is expected, and deterioration of the catalyst due to the high-temperature exhaust heat and damage caused thereby can be effectively prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual illustration of a power transmission structure of a mild hybrid vehicle including a catalyst protection device according to an aspect of the present invention; FIG.
2 is a block diagram schematically illustrating a catalyst protection apparatus according to an embodiment of the present invention;
3 is a flow chart applied for preventing catalyst deterioration.

Hereinafter, the terms used in the description of the present invention are used only for describing specific embodiments and are not intended to limit the present invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. It is to be understood that the terms "comprises", "having", and the like in the specification are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

Also, the terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

In addition, the terms " part, "" unit," " module, "and the like, which are described in the specification, refer to a unit for processing at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software .

In the following description with reference to the accompanying drawings, the same reference numerals are given to the same constituent elements, and a duplicate description thereof will be omitted. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

A catalyst protecting apparatus according to an embodiment of the present invention protects a catalyst of a purifier installed in an exhaust line for purifying exhaust gas from deterioration. When the exhaust gas temperature rises to the catalyst deterioration temperature, To prevent deterioration of the catalyst by reducing the temperature of the exhaust gas and to compensate the output of the engine that is insufficient due to the output restriction of the engine so that a desired output can be obtained.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 conceptually illustrates a power transmission structure of a mild hybrid vehicle including a catalyst protection device according to an aspect of the present invention. Referring to FIG. 1, the concept of a mild hybrid system will be briefly described.

Referring to FIG. 1, a mild hybrid vehicle includes an engine 10 using fossil fuel and a motor 20 that assists the engine output and makes electricity. The output of the motor 20 can be adjusted in accordance with the control value determined by the control unit 76, for example, the intensity of the supply voltage in accordance with the driving condition of the vehicle, Thereby assisting the power output from the engine 10.

The output shaft of the motor 20 is directly connected to the output shaft of the engine 10, specifically, to one end of the crankshaft or is connected to the output shaft of the engine 20 via a belt or a chain so as to transmit power. A transmission 40 for transmitting the power output from the engine 10 to the drive wheels in accordance with the driving conditions is intermittently supplied with power from the engine 10 through the clutch 30.

An exhaust line 50 for the external exhaust of the combustion exhaust gas is formed on the exhaust side of the engine 10. An exhaust gas purifier 60 for reducing the harmful components contained in the exhaust gas is provided in the middle of the exhaust line. At this time, the exhaust gas purifying apparatus 60 includes a catalyst (Catalyst) 65 exhibiting a purifying performance under an appropriate temperature condition, and a catalyst protecting apparatus for preventing deterioration of the catalyst due to high temperature exhaust heat is provided.

Hereinafter, a catalyst protecting apparatus according to an aspect of the present invention will be described.

2 is a schematic block diagram of a catalyst protection apparatus according to an embodiment of the present invention.

2, the catalyst protecting device 70 is an apparatus for preventing the engine 20 from deteriorating in the exhaust gas purifying apparatus 600 in the mild hybrid vehicle assisting the motor 20 And an exhaust gas temperature monitoring section 72. The exhaust gas temperature monitoring section 72 estimates or detects the temperature of the exhaust gas flowing along the engine exhaust line 50 and compares the estimated or detected temperature information (74).

The exhaust gas temperature monitoring section 72 preferably uses the map including the exhaust gas temperature change information according to the change of the driving condition of the vehicle (or the engine output) And may output the estimated temperature information to the comparison determination unit 74 as current exhaust gas temperature information.

The map can be provided in the form of obtaining the catalyst temperature data which rises when the engine output is increased by an arbitrary value through repeated experiments or simulations and arranging the obtained data in the form of a table and storing it in a recording device or the like In this case, when the information on the driving condition of the vehicle (or the engine output) is input, the temperature information of the stored catalyst can be selected and output.

The exhaust gas temperature monitoring unit 72 may be disposed upstream or downstream of the purifier 60 installed in the engine exhaust line 50 on the basis of the flow direction of the exhaust gas, (Not shown) that directly detects the temperature of the exhaust gas flowing along the exhaust gas temperature sensor, and may output the exhaust gas temperature information obtained through the temperature sensor to the comparison determination unit 74.

The temperature information estimated or detected by the exhaust gas temperature monitoring unit 72 is transmitted to the comparison determination unit 74 as described above. The comparator 74 compares the received temperature information with the deterioration reference threshold temperature of the catalyst 65 to determine whether the information provided by the exhaust gas temperature monitoring unit 72, It is determined whether or not the exhaust gas temperature has reached the deterioration reference threshold temperature.

If it is determined that the temperature of the exhaust gas of the present vehicle is equal to or higher than the deterioration reference threshold temperature as a result of the comparison by the comparison determination unit 74, the control start signal is generated by the comparison determination unit 74, The control unit 76 outputs a predetermined control signal for preventing deterioration of the catalyst from the time when the control start signal is received, preferably, a predetermined output control for controlling the output of the engine 10 and the motor 20. [ .

Specifically, the control unit 76 performs engine output control for limiting the engine output to a certain level at the point of time when the control change signal is input. At the same time, the output of the motor 20 is increased corresponding to the relatively shortened engine output shortage (the difference between the engine target output and the actual engine output limited for preventing deterioration of the catalyst) As shown in Fig.

The engine output limitation for preventing deterioration of the catalyst can be realized by controlling the air amount adjusting actuator and the fuel injection injector so that the actual air-fuel ratio (mixing ratio of air and fuel) does not exceed the stoichiometric air-fuel ratio (14.7: 1). That is, even if there is a request for increasing the engine output, the actual air-fuel ratio is limited to the stoichiometric air-fuel ratio level so that the engine output does not exceed a certain level.

The control unit 76 preferably can be divided into two parts in terms of functionality for efficient motor output control through role sharing. More specifically, a motor output calculation unit 76a calculates a motor output value corresponding to the engine output that is subjected to an output limitation using a predetermined algorithm, and a motor output calculation unit 76b that substantially calculates a motor output And a control unit 76b.

The motor output calculating section 76a calculates the difference value between the target output (demand output) of the engine 10 automatically set in accordance with the engine output adjusting means, for example, the accelerator pedal operation, and the engine output limited for preventing deterioration of the catalyst To calculate the engine output shortage. And serves to calculate an engine output that is insufficient by the engine output shortage as an output value of the motor 20.

The motor output control unit 76b determines the control value of the motor 20 corresponding to the output value of the motor 20 output by the motor output calculation unit 76a By controlling the output of the motor 20 with the control value, the motor 20 compensates for the engine output corresponding to the relatively shortened engine output shortage due to the output limitation.

That is, the catalyst protecting apparatus 70 according to one aspect of the present invention prevents the deterioration of the catalyst by limiting the output of the engine 10 to lower the exhaust gas temperature when the exhaust gas temperature rises to the catalyst deterioration temperature, And the motor 20 compensates for the output of the engine 10 that is insufficient to prevent the deterioration of the catalyst.

Hereinafter, a method of protecting a catalyst for preventing deterioration of a catalyst performed by the catalyst protecting apparatus according to an aspect of the present invention will be described in connection with the operation of the catalyst protecting apparatus.

Fig. 3 is a flowchart applied for preventing catalyst deterioration.

Referring to FIG. 3, the method for protecting a catalyst according to another aspect of the present invention includes an exhaust gas temperature monitoring step (S100) for estimating or detecting the temperature of exhaust gas flowing along an engine exhaust line. In the exhaust gas temperature monitoring step, the temperature of the exhaust gas flowing along the engine exhaust line is estimated or detected through the exhaust gas temperature monitoring unit.

In the exhaust gas temperature monitoring step, preferably, information necessary for grasping the driving condition of the vehicle is acquired from the sensors of each vehicle, and the current vehicle is detected using a map including information on the relationship between the driving condition and the exhaust gas temperature The temperature of the exhaust gas flowing through the exhaust line can be directly detected by using the temperature detection sensor.

The temperature information estimated or detected in the exhaust gas temperature monitoring step is transmitted to the comparison determination unit, and a process of comparing the estimated or detected temperature with the deterioration reference threshold temperature of the catalyst is performed through the comparison determination unit Comparison determination step, S200). Specifically, it is determined whether or not the exhaust gas temperature of the presently-recognized vehicle has reached the deterioration reference threshold temperature.

If the temperature of the exhaust gas is equal to or higher than the deterioration reference threshold temperature as a result of the comparison and determination, the comparison start signal is output to the control unit. When the control start signal is input, (S300) in which the exhaust gas temperature is lowered or the temperature rise is suppressed by limiting the engine output in order to prevent deterioration of the exhaust gas temperature.

In the output limiting step, the air amount adjusting actuator and the fuel injection injector are preferably controlled so as to limit the engine output so that the air-fuel ratio (mixing ratio of air and fuel) does not exceed the stoichiometric air-fuel ratio (14.7: 1). That is, even if there is a request for increasing the engine output, the actual air-fuel ratio is limited to the stoichiometric air-fuel ratio level so that the engine output does not exceed a certain level.

Subsequently, control is performed by the control unit (output compensation step, S400) to compensate for the engine output that has been insufficient due to the output restriction, that is, the engine output increased by the engine output shortage relative to the insufficient engine output. In other words, the output compensation step (S400) compensates the relatively insufficient engine output due to the output limitation through the control for increasing the output of the motor.

Specifically, in the output compensation step (S400), the engine output shortage is calculated from the difference between the engine target output (demand output) set according to the operation of the accelerator pedal and the engine output limited for preventing deterioration of the catalyst, And the motor control value corresponding to the motor output value is determined.

By controlling the output of the motor on the basis of the determined control value, the engine output that is insufficient by the engine output shortage can be compensated through the motor. Specifically, the control unit determines the intensity of the allowable supply voltage for the motor corresponding to the engine output shortage, and adjusts the output of the motor to the determined allowable supply voltage to compensate the engine output.

According to the embodiments of the present invention described above, when the catalyst of the exhaust gas purifying apparatus becomes close to the deterioration temperature, the output of the engine is limited to lower the exhaust gas temperature, It is possible to reduce fuel consumed to prevent deterioration of the catalyst and to improve the fuel economy and to effectively prevent deterioration of the catalyst due to high-temperature exhaust heat and damage thereof.

In the foregoing detailed description of the present invention, only specific embodiments thereof have been described. It is to be understood, however, that the invention is not to be limited to the specific forms thereof, which are to be considered as being limited to the specific embodiments, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. .

10: engine 20: motor
30: clutch 40: transmission
50: exhaust line 60: exhaust gas purifier
65: Catalyst 70: Catalytic protection device
72: Exhaust gas temperature monitoring section
74: comparison judgment unit 76:
76a: Motor output calculating section 76b: Motor output control section

Claims (10)

An apparatus for preventing catalyst deterioration of an exhaust gas purifying apparatus in a mild hybrid vehicle in which the motor assists the engine output,
An exhaust gas temperature monitoring unit for estimating or detecting the temperature of the exhaust gas flowing along the engine exhaust line and transmitting the estimated or detected temperature information to the comparison determination unit;
A comparison determination unit for receiving the temperature information estimated or detected from the exhaust gas temperature monitoring unit and comparing the temperature information with the deterioration reference threshold temperature of the catalyst; And
When the temperature of the exhaust gas is equal to or higher than the deterioration reference threshold temperature, the engine output is limited in order to prevent deterioration of the catalyst according to the control start signal output by the comparison and determination unit, And a control unit that performs control to compensate for a lack of engine output.
The method according to claim 1,
The exhaust gas temperature monitoring unit may include:
An exhaust gas temperature corresponding to the current operating condition of the vehicle is estimated by using a map including information on the relationship between the operating condition of the vehicle and the exhaust gas temperature and the estimated temperature information is compared with the current exhaust gas temperature information And outputs it to the determination unit.
The method according to claim 1,
The exhaust gas temperature monitoring unit may include:
And a temperature detection sensor provided on an upstream side or downstream side of the purifying device installed in the engine exhaust line with reference to the flow direction of the exhaust gas and directly detecting the temperature of the exhaust gas flowing along the exhaust line, And outputs the obtained exhaust gas temperature information to the comparison determination unit.
The method according to claim 1,
Wherein,
The engine output shortage is calculated from the difference value between the engine target output (required output) set according to the operation of the accelerator pedal and the engine output limited to prevent deterioration of the catalyst, and the engine output, which is shortened by the engine output shortage, A motor output calculating section for calculating a motor output;
And a motor output control unit for determining a motor control value corresponding to the motor output value and for controlling an output of the motor based on the determined control value to make the motor compensate for an engine output that is insufficient by an insufficient engine output A catalytic protection device for a mild hybrid vehicle.
The method according to claim 1 or 4,
(Air / fuel mixture ratio) does not exceed the stoichiometric air-fuel ratio (14.7: 1) in order to prevent the deterioration of the catalyst, so that the engine output is limited by controlling the air amount adjusting actuator and the fuel injection injector Protection device.
A method for preventing catalyst deterioration of an exhaust gas purifying apparatus in a mild hybrid vehicle in which the motor assists the engine output,
An exhaust gas temperature monitoring step (S100) for estimating or detecting the temperature of the exhaust gas flowing along the engine exhaust line;
A comparison determination step (S200) of comparing the temperature information estimated or detected in the exhaust gas temperature monitoring step with the deterioration reference critical temperature of the catalyst (Catalyst); And
An output limiting step (S300) of limiting the engine output to prevent deterioration of the catalyst when the exhaust gas temperature is equal to or higher than the degradation reference threshold temperature as a result of the comparison;
And an output compensating step (S400) of compensating for an insufficient engine output by increasing an output of the motor by an insufficient engine output.
The method according to claim 6,
In step S100,
Information necessary for grasping the driving condition of the vehicle is obtained from the sensors of each part of the vehicle and an exhaust gas temperature corresponding to the operating condition of the present vehicle detected using a map including information on the relationship between the operating condition and the exhaust gas temperature And estimating the catalytic amount of the catalyst.
The method according to claim 6,
In step S100,
Wherein the temperature of the exhaust gas flowing along the exhaust line is directly detected using a temperature detection sensor.
The method according to claim 6,
In step S300,
Wherein the engine output is controlled by controlling the air quantity adjusting actuator and the fuel injection injector so that the air-fuel ratio (mixing ratio of air and fuel) does not exceed the stoichiometric air-fuel ratio (14.7: 1).
The method according to claim 6,
In step S400,
The engine output shortage is calculated from the difference value between the engine target output (required output) set according to the operation of the accelerator pedal and the engine output limited to prevent deterioration of the catalyst, and the engine output, which is shortened by the engine output shortage, However,
The motor control value corresponding to the motor output value is determined and the output of the motor is controlled based on the determined control value to make the motor compensate for the engine output that is insufficient for the insufficient engine output. Way.

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