KR20160006072A - Method for controlling for rising engine-generatiing using nox concentration - Google Patents

Abstract

Disclosed is a method to control and improve the output of a vehicle engine by using the concentration of a nitrogen oxide. The method includes: a step (a) of deriving a caloric value of exhaust gas of a vehicle within a set temperature range of a nitrogen oxide in exhaust gas, and inputting the derived caloric value into an engine ECU; a step (b) of measuring the amount of a nitrogen oxide, included in the exhaust gas, by using a nitrogen oxide sensor, installed in the vehicle; a step (c) of controlling a supply amount of fuel, supplied to the engine, under the control of the engine ECU to reduce the supply amount at a set ratio if the amount of the nitrogen oxide, measured at the step (b), is not less than a set reference amount; and a step (d) of controlling the supply amount of fuel, supplied to the engine, under the control of the engine ECU to increase the supply amount at a set ratio if the amount of the nitrogen oxide, measured at the step (b), is less than the set reference amount.

Description

TECHNICAL FIELD [0001] The present invention relates to a control method for controlling the output of a vehicle engine using nitrogen oxide (NOx)

The present invention relates to a method for controlling the output of a vehicle engine using a nitrogen oxide concentration capable of improving the combustion stability of the vehicle and improving the engine output.

At present, high calorific natural gas is decreasing worldwide, and pipe natural gas (PNG, Pipe line Natural Gas) is increasing.

Accordingly, it is expected that the domestic natural gas supply gradually becomes low in calorific value, and it is required to carry out research for minimizing the problems of domestic industrial gas equipment using natural gas as a fuel and countermeasures for efficient use .

On the other hand, in a gas engine using natural gas as a raw material, there is a problem that when the gas component is varied, the initial start stability and the idling operation stability are weakened.

That is, in the conventional gas engine, there is a problem that the gas component frequently fluctuates and the fuel consumption rate due to optimization deviation of the ignition timing may be increased. Also, in the conventional gas engine, lean burn occurs There is a problem that the engine operation stability is deteriorated due to the irregular number of revolutions of the engine due to the combustion instability.

An object of the present invention is to provide a method for controlling the output of a vehicle engine using a nitrogen oxide concentration capable of improving the engine output by controlling the amount of fuel in the vehicle in response to a measured amount of nitrogen oxide contained in the exhaust gas .

(A) deriving a calorific value of the exhaust gas in a set range of nitrogen oxide contained in the exhaust gas of the vehicle, and inputting the derived calorific value to the engine ECU, (b) (B) determining whether the amount of nitrogen oxides measured in the step (b) is equal to or greater than a predetermined reference amount; and (c) comparing the amount of nitrogen oxides contained in the exhaust gas with the amount of nitrogen oxides contained in the exhaust gas, (D) when the measured amount of nitrogen oxide measured in the step (b) is less than the set reference amount, the control is performed by the control of the engine ECU And controlling the amount of supplied fuel supplied to the engine to increase by a predetermined ratio.

wherein the step (a) includes the steps of: (a-1) stepwise changing the amount of nitrogen oxide contained in the exhaust gas; and (a-2) And deriving a calorific value of the gas.

In the step (a-2), the calorific value of the exhaust gas can be derived by the following equation.

[Equation]

y = 275.96 lnx + 8742.9

Here, y is the amount of heat generated by the exhaust gas, and x is the amount of nitrogen oxide contained in the exhaust gas.

의 발열량에 대해 공급 연료량을 5.88% 체적의 비율로 감소시키는 단계를 포함할 수 있다.(c) comprises the steps of (c-1) deriving a first calorific value by substituting the reference amount of nitrogen oxide contained in the exhaust gas into the equation, and (c-2) measuring the amount of nitrogen oxide contained in the exhaust gas (C-3) calculating the first calorific value at the second calorific value to a first calorific value at the first calorific value,

And reducing the amount of supplied fuel to a calorific value of 5.88% by volume.

의 발열량에 대해 공급 연료량을 5.88% 체적의 비율로 증가시키는 단계를 포함할 수 있다.(d) includes the steps of (d-1) deriving a first calorific value by substituting the reference amount of nitrogen oxide contained in the exhaust gas into the equation, and (d-2) calculating a measured amount of nitrogen oxide contained in the exhaust gas (C-3) calculating the third calorific value at the first calorific value to the first calorific value at the first calorific value,

And increasing the supply fuel amount to a calorific value of 5.88% by volume.

According to an embodiment of the present invention, the concentration of nitrogen oxide contained in the exhaust gas exhausted from the vehicle engine is measured using a nitrogen oxide sensor, the amount of fuel supplied to the vehicle engine is varied corresponding to the measured nitrogen oxide concentration The combustion stability of the engine can be improved by maintaining the proper air-fuel ratio range of the engine.

According to the embodiment of the present invention, it is possible to supply the engine with an appropriate air-fuel ratio, optimize the ignition timing and appropriately maintain the fuel consumption rate, thereby improving the engine output.

According to an embodiment of the present invention, it is possible to optimize the operation of the engine, thereby preventing the increase of the hazardous exhaust material contained in the exhaust gas.

1 is a flowchart schematically illustrating a method for controlling an output of a vehicle engine according to an embodiment of the present invention.
2 is a graph showing the change in output performance according to nitrogen oxide measurement and fuel amount control.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

1 is a flowchart schematically illustrating a method for controlling the output of a vehicle engine using a nitrogen oxide concentration according to an embodiment of the present invention. Hereinafter, a method for controlling the output of a vehicle engine according to an embodiment of the present invention will be described in detail with reference to the drawings. The engine described below can be applied to a gas engine using natural gas or a mixture of natural gas and hydrogen as a fuel.

First, the calorific value of the exhaust gas is derived from the set range of the nitrogen oxide contained in the exhaust gas of the vehicle, and the derived calorific value is input to the engine ECU (S10). (S10) derives the calorific value of the exhaust gas derived corresponding to the amount of nitrogen oxides in the gas engine provided with the nitrogen oxide sensor, and inputs the derived calorific value to the engine ECU.

The nitrogen oxide sensor is installed in the engine so that the amount of nitrogen oxides contained in the exhaust gas discharged from the engine can be confirmed. The configuration of the nitrogen oxide sensor is well-known and its detailed description will be omitted. Hereinafter, the step (S10) will be described in more detail.

First, the amount of nitrogen oxide contained in the exhaust gas is changed step by step (S11). The stepwise change in the amount of nitrogen oxide contained in the exhaust gas in the step (S11) is intended to confirm the degree of change in the calorific value corresponding to the amount of the changed nitrogen oxide. In this embodiment, the change of the nitrogen oxide in the step (S11) can be changed step by step on the basis of 1 ppm (parts per million) unit.

Next, in step S11, the calorific value of the exhaust gas is derived corresponding to the amount of nitrogen oxide that has been changed step by step (S12).

The derivation of the calorific value of the exhaust gas in the step S12 is to supply the amount of fuel supplied to the engine in accordance with the calorific value of the exhaust gas in an appropriately changed state to ensure the combustion stability of the engine.

That is, it is possible to ensure the combustion stability without changing the ignition timing by controlling the proper fuel supply so as to correspond to the calorific value of the exhaust gas discharged from the engine. This will be described in more detail below.

In this embodiment, the calorific value that changes in accordance with the temperature change of the exhaust gas in the step S12 can be derived by the following equation.

[Equation]

y = 275.96 lnx + 8742.9

Where y is the calorific value of the exhaust gas and x is the amount of nitrogen oxide contained in the exhaust gas.

2 is a graph showing the change in output performance according to nitrogen oxide measurement and fuel amount control.

As shown in FIG. 2, when the calorific value is decreased without controlling the engine, the nitrogen oxide shows 21 ppm.

And, in the case of the lambda control, when controlling to increase the fuel amount to the level corresponding to the air excess ratio 1.6, the nitrogen oxide shows 358 ppm.

In addition, when the lambda control and the torque control are performed together, when the fuel amount is increased to the level corresponding to the excess air ratio of 1.6, and the torque control using the throttle opening increase is also performed, the nitrogen oxide is 373 ppm .

As described above, the lambda control alone control, the lambda control and the throttle opening control are compared, and it can be confirmed that the nitrogen oxide emission amount is controlled stably without fluctuation even in the low calorific value by controlling the fuel supply amount.

Next, the temperature of the exhaust gas is measured using a nitrogen oxide sensor installed in the vehicle (S20).

Next, the amount of nitrogen oxide measured in step S20 is checked (S30). If it is confirmed that the amount of NOx is equal to or higher than the set reference concentration, control is performed so as to reduce the amount of supplied fuel to the engine under the control of the engine ECU (S40). The reduction of the amount of the supplied fuel supplied to the engine in the step S40 is for reducing the amount of fuel supplied to the engine to ensure the combustion stability of the engine when the measured amount of nitrogen oxides exceeds the set reference concentration.

More specifically, the step (S40) will be described. First, the amount of nitrogen oxide (x) contained in the exhaust gas is substituted into the above equation to derive the first heating value y at the reference concentration of nitrogen oxide (S41 ).

Subsequently, a measured amount of nitrogen oxide is substituted into the above equation to derive a second heating value (y) at the measured concentration (S42).

Then, the second calorific value measured in the step (S42) is subtracted from the first calorific value measured in the step (S41) to derive the final calorific value.

As described above, the amount of fuel supplied to the engine is reduced and supplied by reducing the fuel flow rate by 5.88% based on 1 kcal / nm ^ 3 with respect to the calorific value finally derived.

Then, the amount of nitrogen oxide contained in the exhaust gas measured in the step S20 is checked (S30). If it is confirmed that the amount of nitrogen oxide is less than the set concentration, control is performed so as to increase the amount of supplied fuel to the engine under the control of the engine ECU S50). The increase of the amount of the supplied fuel supplied to the engine in the step S50 is to reduce the amount of fuel supplied to the engine to assure the combustion stability of the engine if the concentration of nitrogen oxides contained in the exhaust gas is less than the reference concentration.

More specifically, the step (S50) will be described. First, the ground concentration (x) of the nitrogen oxide contained in the exhaust gas is substituted into the equation to derive the first heating value (y) at the reference concentration of nitrogen oxide (S51 ).

Next, the measured concentration of nitrogen oxide contained in the exhaust gas is substituted into the equation to derive the third heating value (y) at the measured concentration of nitrogen oxide (S52).

Next, the third calorific value measured in step S52 is subtracted from the first calorific value measured in step S51 to derive the final calorific value.

를 기준으로 연료 유량 5.88%를 감소시켜 엔진에 공급되는 연료량을 증가시켜 공급한다. Then, for the calorific value derived by the equation, 1

, The fuel flow rate is reduced by 5.88% to increase the amount of fuel supplied to the engine.

As described above, the amount of nitrogen oxide contained in the exhaust gas exhausted from the vehicle engine is measured using a nitrogen oxide sensor, and the amount of fuel supplied to the vehicle engine is varied and supplied corresponding to the concentration of the measured nitrogen oxide It is possible.

Therefore, it is possible to improve the combustion stability of the engine by supplying the fuel so as to maintain the proper air-fuel ratio range in accordance with the concentration change of the nitrogen oxide contained in the exhaust gas in the gas engine of this embodiment.

Further, the fuel can be supplied to the gas engine at an appropriate air-fuel ratio, the ignition timing can be optimized, and the fuel consumption rate can be made appropriate, thereby improving the engine output as the engine thermal efficiency is improved.

In addition, it is possible to optimally operate the gas engine, and it is possible to prevent the hazardous exhaust material contained in the exhaust gas from being increased.

The present invention has been described above with reference to the embodiments shown in the drawings. However, the present invention is not limited thereto, and various modifications or other embodiments falling within the scope of the present invention are possible by those skilled in the art.

Claims (5)

(a) deriving a calorific value of the exhaust gas in a set range of nitrogen oxide contained in the exhaust gas of the vehicle, and inputting the derived calorific value to the engine ECU;
(b) measuring an amount of nitrogen oxide contained in the exhaust gas using a nitrogen oxide sensor installed in the vehicle;
(c) when the measured amount of the nitrogen oxide measured in the step (b) is determined to be equal to or greater than the set reference amount, controlling to reduce the supplied fuel amount supplied to the engine under the control of the engine ECU at a predetermined ratio; And
(d) controlling, when the measured amount of nitrogen oxide measured in the step (b) is less than the set reference amount, increasing the supplied fuel amount supplied to the engine under the control of the engine ECU by a predetermined ratio;
And a control unit for controlling the output of the engine. The method according to claim 1,
The step (a)
(a-1) stepwise changing the amount of the nitrogen oxide contained in the exhaust gas; And
(a-2) deriving a calorific value of the exhaust gas corresponding to the changed amount of the nitrogen oxide in the step (a-1);
And a control unit for controlling the output of the engine. 3. The method of claim 2,
Wherein the step (a-2) derives the calorific value of the exhaust gas by the following equation.
y = 275.96 lnx + 8742.9
Here, y is the amount of heat generated by the exhaust gas, and x is the amount of nitrogen oxide contained in the exhaust gas. The method of claim 3,
The step (c)
(c-1) deriving a first calorific value by substituting the reference amount of the nitrogen oxide contained in the exhaust gas into the equation;
(c-2) deriving a second calorific value by substituting the measured amount of the nitrogen oxide contained in the exhaust gas into the equation; And
(c-3) the first calorific value at the second calorific value is set to 1

Reducing the supplied fuel amount to a calorific value of 5.88% volume;
And a control unit for controlling the output of the engine. The method of claim 3,
The step (d)
(d-1) deriving a first calorific value by substituting the reference amount of the nitrogen oxide contained in the exhaust gas into the equation;
(d-2) deriving a third calorific value by substituting the measured amount of the nitrogen oxide contained in the exhaust gas into the equation; And
(c-3) the third calorific value at the first calorific value is set to 1

Increasing the amount of the supplied fuel to a calorific value of 5.88% by volume;
And a control unit for controlling the output of the engine.

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