KR101430399B1 - Engine Analysis Apparatus Using Oxygen Sensor - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle, The present invention relates to a method and an apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle capable of diagnosing a malfunction after analysis.
According to the present invention, it is possible to diagnose a failure by checking the combustion state of the engine by analyzing the oxygen sensor output signal value mounted on the exhaust pipe of the vehicle with the engine speed or the injector ignition signal have.
In addition, it is possible to utilize the characteristic of the oxygen sensor signal according to the basic operation principle and characteristics of the vehicle engine, without having to separately constitute a characteristic database for each vehicle type, even for various types of engines having various conditions such as the amount of exhaust and the number of cylinders. So that it is possible to perform efficient state diagnosis and fault checking.

Description

TECHNICAL FIELD [0001] The present invention relates to an engine analysis apparatus and an oxygen sensor,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle, The present invention relates to a method and an apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle capable of diagnosing a malfunction after analysis.

Generally, the oxygen sensor is installed at the front end and the rear end of the catalyst for purifying harmful substances such as CO, HC, NOx contained in the exhaust gas to detect the oxygen concentration contained in the exhaust gas, So that the supply state can be maintained at the stoichiometric air-fuel ratio, and the oxygen sensor at the downstream stage provides the engine control means with the air-fuel ratio control signal so as not to change the catalyst purification rate.

The planar type oxygen sensor outputs a rich signal when the oxygen concentration in the reference air chamber is higher than the outside and outputs a lean signal when the oxygen concentration outside the reference air chamber is higher than the reference air chamber. The rich / lean signal corresponding to the difference in oxygen concentration is generally a voltage value of a signal output through the oxygen sensor, and may be 0-1 volts (zirconia type) or 0-5 volts (Titania type), and the wide-area oxygen sensor mounted on the lean-burn engine or the diesel engine is a zirconia type. The voltage output is linearly outputted according to the concentration of oxygen and is outputted in the range of 0-5 volts. When the air-fuel ratio supplied to the air-fuel ratio sensor has an air-fuel ratio (AFR) value, the signal output is higher and lower than the reference value based on the middle value of the signal range. In the case of lean burn engines and diesel engines, it is common that the signal output is constant according to the lean ratio.

Hereinafter, the present invention will be described on the basis of the most commonly used vocalian type, and the maximum range in which the oxygen sensor signal is output is defined as a maximum width (Ho) as shown in FIG.

As a conventional invention related to the oxygen sensor described above, Japanese Patent Application Laid-Open No. 10-2010-0031328 ("apparatus and method for diagnosing oxygen sensor pollution in vehicles") in Patent Document 1 is disclosed.

The technique of Patent Document 1 is a technique in which an activity counter is set for the contamination diagnosis of the oxygen sensor and diagnosis is not carried out for the contamination by the organic compound caused by foreign matter during the number of times of the active counter after assembly, Diagnosis is possible for single wire failure.

However, this conventional invention is merely to diagnose the contamination or poor mounting of the oxygen sensor itself, and it is impossible to diagnose the combustion state of the engine of the vehicle.

On the other hand, the output value of the oxygen sensor continuously changes in real time during operation, and may vary depending on the vehicle type. However, when there is more oxygen than the reference concentration value in the exhaust gas, Lean signal. When oxygen is present in the exhaust gas in a smaller amount than the reference concentration value, it is output so as to have a voltage equal to or higher than a reference value. This signal is referred to as a rich signal. In some cases, the opposite is true.

Generally, when the exhaust gas contains more oxygen than the reference concentration value, the fuel ratio may be smaller than the air amount based on the stoichiometric air-fuel ratio. However, there may be a case where the air- There is a case where a large amount of oxygen remains.

In this case, when the fuel is burned due to ignition failure or the like, oxygen remains and when the fuel injected from the injector flows into the combustion chamber, the fuel is injected to the inside of the intake or to the top of the intake valve, Or when there is a shortage of fuel due to fuel pump or fuel filter failure, clogging of injector or leakage of injector o-ring, insufficient air tightness in the air intake system after the position of the intake air amount sensor that detects the amount of intake air In the case where the outside air is abnormally introduced into the combustion chamber and the outside air is introduced into the exhaust pipe due to the leakage of the exhaust pipe, the measurement value failure in the mass air flow / MAP (Mafium absolute pressure) And the amount of air that is actually larger than the amount actually required may be introduced into the combustion chamber The.

On the other hand, when the fuel ratio is higher than the stoichiometric air-fuel ratio in the case where the oxygen concentration is lower than the reference concentration value in the exhaust gas, the fuel gas is excessively introduced from the evaporative gas collection line Fuel oil film (Wall film: A film formed by applying a fluid component to a wall surface. In the field of engine electronic control development, a fuel film formed by injecting fuel injected from an injector is called a wall film) When an inflow of lubricating oil into the combustion chamber or an abnormal oil penetration into the combustion chamber occurs, a smaller amount of air than the actual required amount due to, for example, a measurement value failure in a mass air flow / MAP (Mamifoid absolute pressure) sensor, And the like.

In the case where the change pattern of the output signal of the oxygen sensor which changes in real time in time is idling on the stoichiometric air-fuel ratio in a normal state engine, a small pulsation (in the technical field of the present invention, (Hereinafter referred to as " switching ") is referred to as " switching, " while the amplitude is the maximum range (Ho) (0.7 times or more), and a shape that repeatedly changes up and down within a range of a constant period (generally 0.5 seconds to 2 seconds in idle, hereinafter referred to as a reference period value (T)). The supplied fuel is much more (fuel rich) than the oxygen air sensor signal (fuel lean) repeatedly based on the stoichiometric air fuel ratio.

However, when the combustion is not properly performed in the engine combustion chamber, or when the ratio of the fuel to the air in each cylinder of the engine is different, the cycle and the amplitude of the oxygen sensor signal are very irregular.

In such an abnormal situation, the amount of air flowing into each cylinder of the engine is abnormally introduced due to a poor airtightness of the intake system (air duct or intake manifold), and the amount of air entering the combustion chamber of each cylinder of the engine differs from each cylinder of the engine (Hereinafter referred to as " defective air distribution "), hereinafter referred to as" defective air distribution ", which differs in the amount of air flowing into the combustion chamber of each cylinder, and in a positive crankcase valve & When the gas is excessively introduced or the fuel gas is excessively introduced from the evaporation gas line, it is not uniformly distributed to each cylinder combustion chamber. When the injector is clogged or the fuel supply of some cylinders is small due to leakage or the like, If there is a defect, the air-fuel ratio does not match for each cylinder of the engine. Therefore, as shown in FIGS. 3A to 3C, the output signal of the oxygen sensor is such that the cycle of switching the signal of the oxygen sensor coincides with the cycle period of the engine.

Comparing this situation with the case of oxygen sensor signal under normal operating conditions is as follows.

FIG. 1 shows a state in which the oxygen sensor signal is normally switched, and 14-22 injector driving signals are output in one period (t) for oxygen sensor switching. That is, since the injector injects fuel 14-22 times during the switching period of the oxygen sensor signal, the injector is driven once every cycle of the engine, so that the switching period of the oxygen sensor signal corresponds to 14-22 cycles of the engine, As a standard, the number of revolutions of the engine is 28-44 revolutions.

More specifically, in a four-cycle engine rotating at 750 rpm, the time of one cycle becomes 150 msec, and the time of one rotation of the engine becomes 75 msec. When the basic cycle (T) of switching of the oxygen sensor is 0.5 seconds to 2 seconds, the corresponding engine rotation speed is 7-27 turns.

However, in the waveforms shown in FIGS. 3A to 3C, it is seen that the switching period of the oxygen sensor signal coincides with the signal to be driven by the injector, so that the switching period of the oxygen sensor signal coincides with one cycle of the engine, The oxygen sensor signal is high and low. The fact that some cylinders have different oxygen concentrations in the exhaust gas compared to other cylinders suggests that the air-fuel ratios do not match each other It shows. Therefore, the term can be defined as "bad air-fuel ratio between cylinders". (Hereinafter referred to as "poor inter-cylinder air-fuel ratio ratio" when the cycle of the oxygen sensor signal switching coincides with one cycle of the engine)

On the other hand, when the air-fuel ratio between the cylinders is poor, waveforms characteristic of each cause have the characteristics as shown in Fig. 3C. When the air-fuel ratio between the cylinders is not defective and the ignition failure and the accumulation of carbon in the intake valve are severe, As shown in FIG.

The waveform characteristics of the output signal of the oxygen sensor corresponding to each of these defect states can be applied to all vehicles equipped with oxygen sensors other than the lean burn engine or the diesel engine vehicle equipped with the wide area oxygen sensor. Even in a very wide variety of engines having different characteristics such as the number and the amount of exhaust, they can be uniformly applied with a certain regularity.

Patent Document 1: Korean Patent Laid-Open No. 10-2010-0031328 (Mar. 22, 2010)

The present invention solves the above problems of the prior art and can be applied to all vehicles equipped with an oxygen sensor except a lean burn engine or a diesel engine vehicle equipped with a wide area oxygen sensor, The waveform characteristic of the output signal of the oxygen sensor corresponding to each of the defect states, which is characterized by being able to be applied uniformly with a certain regularity even in a very different engine of different types, A method and an apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle capable of diagnosing a malfunction by checking the state of the engine by merely analyzing the engine speed or the injector ignition signal by using the feature We do thing as problem.

It is another object of the present invention to provide an engine combustion state inspection analysis method and apparatus using an oxygen sensor signal of a vehicle capable of efficiently performing state diagnosis and failure checking for various types of engines having various conditions such as the amount of exhaust and the number of cylinders, We will do it.

In order to accomplish the above object, the present invention provides a method for analyzing an engine combustion state using an oxygen sensor signal of a vehicle, comprising the steps of: outputting an oxygen sensor output signal s, an engine speed signal r, (S1) inputting a sensor signal (I)

A period measuring step (S2) of detecting and measuring the period (t) of the output signal (s) of the oxygen sensor;

A period proportion determining step (S3) of determining whether the period (t) measured in the period measuring step (S2) is proportional to either the injector driving signal (I) or the engine speed signal (r); ,

Determining a fluctuation width (h) of the output signal (s) of the oxygen sensor when the period (t) is proportional to the engine speed signal (r) in the period proportion determining step (S3) );Wow,

(T) during the increase and decrease of the engine speed while increasing and decreasing the engine speed by sequentially instructing the engine to accelerate and decelerate when the variation width (h) is smaller than the output width (H) (S5) for determining whether or not the engine speed is proportional to the engine speed signal (r) during the increase and decrease of the engine speed;

If the period t is not proportional to the engine speed signal r in the step S3 of determining the number of revolutions, the cycle value determining step of comparing the period t with the reference period value T (S6); And a control unit.

If the period t is greater than the reference period T in step S6, the period value variation determination step S7 may be performed to determine a variation of the period t with respect to time. Further comprising:

The determination result through the period proportional determination step S3, the switching amplitude determination step S4, the acceleration / deceleration speed proportional determination step S5, the period value determination step S6, and the period value variation determination step S7 Depending on the,

If the period t is equal to any one of the injector driving signals I and the variation width h is larger than the output width H in the period proportion determining step S3, Failure determination step S8b;

Wherein the period t during the increase and decrease of the engine speed in the acceleration / deceleration rate proportioning step S5 is proportional to the engine speed signal r during the increase and decrease of the engine speed (S8c) judging that the valve is defective,

Wherein the period t during the increase and decrease of the engine speed in the acceleration / deceleration rate proportioning step S5 is proportional to the engine speed signal r during the increase and decrease of the engine speed (S8d) judging that there is a defect in the intake system,

An ignition system failure determination step (S8e) for determining that the ignition system is defective when the period (t) is less than the reference period value (T) in the period value determination step (S6)

A normal determination step (S8f) of determining normal if the fluctuation range of the period (t) with time is similar within a range of 0.8 to 1.2 times in the period value determination step (S7);

If it is determined that the fluctuation range of the period (t) over time is out of the range of 0.8 to 1.2 times in the period value fluctuation determination step (S7), the intake valve carbon accumulation check determination step S8g); And further comprising:

The sensor signal input step S1 further comprises a filtering step S1a for filtering the noise of the output signal s of the oxygen sensor,

(S9b-S8b) for displaying the contents of the malfunction, the similar malfunction, and the necessary repair measures in response to the malfunction state after the injector malfunction determination step (S8b) to the intake valve carbon accumulation maintenance determination step (S8g) S9g); Wow,

A database storage step of storing each vehicle inspected analysis result analyzed for each of the injector failure determination step (S8b) to the intake valve carbon accumulation check determination step (S8g) in a database including the history of each vehicle; And further comprising:

The apparatus for analyzing and checking the engine combustion state using the oxygen sensor signal of the vehicle according to the present invention includes an engine combustion state inspection analyzing apparatus using the oxygen sensor signal of the vehicle performing the engine combustion state inspection analysis method using the oxygen sensor signal of the vehicle In this case,

An output signal s of the oxygen sensor, an engine speed signal r, and an engine speed signal r, which are connected to the sensor signal output unit 20 including the OBD-2 connector 10 of the vehicle, A sensor input / output connection 110 for receiving each injector drive signal I of each cylinder,

A main control unit 120 connected to the sensor input / output connection unit 110 for performing an engine combustion state inspection analysis method using the oxygen sensor signal of the vehicle according to any one of claims 1 to 4;

A display unit 130 connected to the main control unit 120 for visually displaying an engine combustion state inspection analysis result and a result,

An operation input unit 140 connected to the main control unit 120 and receiving a user's operation input; And a control unit.

The main control unit 120 is connected to the main control unit 120 by using at least one of a wireless communication module 150 or an internet network 160. The main control unit 120 is connected to the main control unit 120, An external terminal device 170 capable of inquiring the execution result of the state inspection analysis method; And further comprising:

According to the present invention, it is possible to diagnose a failure by checking the state of the engine by merely analyzing the oxygen sensor output signal value mounted on the exhaust pipe of the vehicle with the engine speed or the injector ignition signal .

In addition, it is possible to utilize the characteristic of the oxygen sensor signal according to the basic operation principle and characteristics of the vehicle engine, without having to separately constitute a characteristic database for each vehicle type, even for various types of engines having various conditions such as the amount of exhaust and the number of cylinders. So that it is possible to perform efficient state diagnosis and fault checking.

FIG. 1 is a view showing an oxygen sensor signal in a normal operating state when performing an engine combustion state inspection analysis method using an oxygen sensor signal of a vehicle according to an embodiment of the present invention. FIG.
2 is a flowchart showing a flow of an engine combustion state inspection analysis method using an oxygen sensor signal of a vehicle according to an embodiment of the present invention;
3A is a diagram showing signal waveforms when the injector failure determination step S8b is performed when the engine combustion state inspection method using the oxygen sensor signal of the vehicle according to the embodiment of the present invention is performed.
FIG. 3B is a diagram showing each signal waveform when performing the valve defect determination step (S8c) when performing an engine combustion state inspection analysis method using an oxygen sensor signal of a vehicle according to an embodiment of the present invention.
FIG. 3C is a diagram showing signal waveforms when performing an intake flaw determination step (S8d) when performing an engine combustion state inspection analysis method using an oxygen sensor signal of a vehicle according to an embodiment of the present invention;
Fig. 4 is a diagram showing signal waveforms when ignition system defect determination step S8e is performed in the case of performing an engine combustion state inspection analysis method using an oxygen sensor signal of a vehicle according to an embodiment of the present invention; Fig.
5 is a block diagram of an apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle according to an embodiment of the present invention.

Hereinafter, a method and an apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that, in the drawings, the same components or parts are denoted by the same reference numerals whenever possible. In describing the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

First, a description will be made of a method for analyzing the combustion state of an engine using an oxygen sensor signal of a vehicle according to an embodiment of the present invention.

As shown in FIG. 2, the method of analyzing the engine combustion state using the oxygen sensor signal of the vehicle according to the present invention can include a sensor signal input step S1, a period measurement step S2, a period proportion determining step S3, An amplitude determination step S4, an acceleration / deceleration speed proportional determination step S5, and an analysis determination step S8.

First, the sensor signal input step S1 will be described. The sensor signal input step S1 is a step of inputting an output signal s of the oxygen sensor, an engine speed signal r, various information relating to the driving state of the angular drive system related to the engine control and the operating state of the vehicle and the engine, (Hereinafter referred to as " service data " in the technical field, hereinafter referred to as service data). In this case, it is preferable that the sensor signals are transmitted from the sensors mounted on the vehicle according to the OBD-2 standard through a controller area network (CAN) or a K-line, The transmission speed is lower than 100 Hz and the data rate is 10 msec or more, which is not comparable to the engine speed, or CAN communication, When a signal is received from an oxygen sensor mounted on a vehicle and the oxygen sensor signal switching is sampled at a speed that is comparatively slower than the engine speed (10 msec or more per data, less than 100 Hz) The signal can not be seen that the oxygen sensor signal switching period is proportional to one cycle of the engine. Therefore, in this case, the oxygen sensor signal and the injector driving signal I and the ignition signal of each cylinder of the engine should be measured and input through the voltage measuring instrument.

OBD-2 (On-Board Diagnosis-2) is one of the regulations related to automobile exhaust gas in the United States, and it is a computer built in a vehicle. When it is judged as a failure by diagnosing an exhaust gas control component or system while a vehicle is running, : Diagnostic Trouble Code (MIL), MIL (Malfunction Indicator Light) is turned on, and the related service data is displayed.

Since the existing OBD systems that were applied for the first time only checked the short-circuit of electronic parts and wiring, it is not known that the exhaust gas increases due to deterioration of the catalyst or oxygen sensor, abnormal behavior of sensor or actuator, The connector, the failure code, the warning light, and the type of the stored information are not standardized. Therefore, different connectors are required for each vehicle or manufacturer, and various other data for interpreting the failure code are required. Respectively.

In order to solve these problems, it is necessary to use the terminology and fault code of the communication connector, the communication specification electronic control part, the unit of the service data, and the display method of the communication device of general purpose diagnostic equipment as a standardized one. The OBD-2 regulation was amended by adding criteria and diagnostic requirements.

OBD-1 is defined as OBD-1, which diagnoses only simple faults related to engine control with a computer built in the vehicle and OBD-1, The OBD-2 is defined as OBD-2. In this case, the OBD-2 is defined as OBD-2. In this case, 2 If the warning light is on If there is not a functional fault and the exhaust gas is too much, there is no problem in driving the vehicle even if it is not repaired. If the warning light is lit, And OBD-3 are defined as comprehensive technical contents for enforcing the improvement measures in case of excessive emission of exhaust gas, such as limiting the operation of the vehicle, etc.

Diagnosis items in accordance with OBD-2 regulations include catalyst, engine misfire, fuel system, leakage of refrigerant refrigerant, leakage of evaporative gas system, oxygen sensor, EGR, thermostat, positive crankcase ventilation (PCV) valve, control of other engine or transmission This includes both sensors and solenoids used for diagnostics and does not specify any specific names or ranges, but includes "all the factors that can cause harmful emissions to be above the norm".

The transmission of data according to OBD-2 regulations is done via CAN or K-Line using ISO9141-2 or KWP2000's vehicle fault diagnosis standard protocol. The ISO 9141-2 and KWP 2000 are standard protocols for vehicle failure diagnosis specified by ISO (International Organization for Standardization) and SAE (Society of Automotive Engineers).

The CAN (Controller Area Network) is a network communication system that can be used in a small-scale range. It is a vehicle network system for providing digital serial communication between various measurement control equipments of an automobile by a next-generation vehicle diagnostic communication method. The CAN satisfies many kinds of real-time demands in a vehicle because it can transmit data at a very high speed, reducing weight and complexity by intelligently replacing complicated electrical wiring and relays of electronic components in a vehicle with a serial communication line. In addition, it can diagnose the abnormality caused by electronic interference, and can organically communicate in an unexpected situation during operation. It is applied to advanced automotive electric system as ISO standard and it is possible to integrate systems such as engine management, anti-lock braking systems (ABS), transmission management system (TMS), air conditioner, door lock, . The transmission speed of the CAN is 500 Kbps to 1 Mbps, which is 50 times faster than the existing communication speed, and it is a tendency to apply this most recently. On the other hand, the K-Line is a diagnostic communication line for vehicles named by OBD regulations and has a speed of 10.4 Kbps.

The present invention is also capable of receiving service data from a vehicle control computer and determining that the signal of the oxygen sensor is proportional to the number of revolutions of the engine is also received at a very high speed through the CAN communication, (100 times less than 100H per second) when receiving the service data through the CAN communication and when the vehicle built-in computer recognizes the signal from the sensor mounted on the vehicle, even if the service data is received through the CAN communication Since we have received a signal with a much lower sensitivity, we can not see that the switching period of the oxygen sensor signal is proportional to one cycle of the engine. Therefore, in this case, it is preferable that the oxygen sensor signal and the injector driving signal I and the ignition signal are measured and inputted to the respective engine cylinders of the engine through the voltage meter.

2, in the sensor signal input step S1, filtering is performed to remove noise of the output signal s of the oxygen sensor, considering sensitivity and resolution of various types of the oxygen sensor, It is preferable to further comprise step S1a.

In this case, a very wide variety of embodiments are possible in which filtering is performed to remove the noise of the output signal s of the oxygen sensor.

In one embodiment of the present invention, the time axis of the output signal s of the oxygen sensor may be discretized for each time period having a predetermined time width, and then filtered according to a discrete equation as shown in Equation 1 below .

In this case, s (n) is the actual value of the output signal s of the oxygen sensor in the nth discrete interval, s (n-1) is the actual value of the output signal s). (N) is a filtered correction value of the output signal s of the oxygen sensor in the n-th discrete interval, and S (n-1) is a filtered correction value of the output signal (s) < / RTI > In the equation (1), K is a correction coefficient or a filtering coefficient, and when the value has a value of 1, the filtered correction value has the same value as the actual value of the output signal (s) of the oxygen sensor, 1, the change of the actual measurement value is mitigated to obtain the filtered value.

As described above, the technique of discretizing the sampling rate and the received signal by filtering the received data is a well-known technology in the field of engine electronic control development, and thus a detailed description thereof will be omitted.

Next, the period measurement step S2 will be described. The period measurement step S2 is a step of detecting and measuring the period t as shown in Fig. 1 of the output signal s of the oxygen sensor, as shown in Fig. In this case, a very wide variety of embodiments are possible in which the period (t) of the output signal s of the oxygen sensor is detected and measured. In one embodiment, the output signal s of the oxygen sensor It is possible to analyze the pattern (pattern) to detect and measure the period t. Meanwhile, in another embodiment of detecting and measuring the period t of the output signal s of the oxygen sensor, the output signal s of the oxygen sensor may be a maximum / minimum value or a predetermined constant reference value It is also possible to detect and measure the period of the output signal s of the oxygen sensor by using the interval between the first rising and falling times of the maximum value and the minimum value. As described above, the technique of detecting and measuring the period of the signal that fluctuates with time, such as the output signal s of the oxygen sensor, is well known in the art to which the present invention pertains, and a detailed description thereof will be omitted.

Next, the period proportion determining step S3 will be described. 2, when the period t measured in the period measuring step S2 is equal to or greater than the period of the injector drive signal I or the engine speed signal r It is judged which one is proportional to. In this case, the meaning of the period t is proportional to either the injector drive signal I or the engine speed signal r means that the period t is shorter than the period t, Which is coincident with the period of the injector drive signal I, or has an integral multiple.

On the other hand, the injector drive signal I has a property that it is proportional to an integer multiple of the engine speed signal r. That is, in the four-stroke engine, the injector of one cylinder is operated once during two rotations of the engine shaft, and the injector of one cylinder is operated once during one rotation of the engine shaft in the two-stroke engine. Accordingly, the injector drive signal I of any one cylinder occurs once during the occurrence of the engine revolution number signal r twice in the case of a four-stroke engine, and in the case of the two-stroke engine, (r) occurs one time.

Next, the switching amplitude determination step S4 will be described. 2, when the period t is proportional to the engine speed signal r in the period proportion determining step S3, the switching amplitude determining step S4 determines the switching amplitude of the oxygen sensor, (h) of the sine wave (s). In this case, the switching amplitude h refers to the amplitude of the switching signal when the switching period of the oxygen sensor signal is proportional to the engine cycle, and is defined as the variation width h.

(= H / H) of the output fluctuation range h of the output signal s of the oxygen sensor is larger than the output width H of the signal during the analysis period in the switching determining step S4 In one embodiment, the pattern of the output signal s of the oxygen sensor is analyzed to determine the switching variation h and the output width s, (H) can be detected and measured. In another embodiment of detecting and measuring the switching variation h and the output width H of the output signal s of the oxygen sensor, a difference between the maximum value and the minimum value during the period t is used It is also possible to detect and measure the switching variation h and the output width H. The switching width h and the output width H of the output signal s of the oxygen sensor are measured in the switching determination step S4 so that the variation width h is smaller than the output width H = h / H) is a well-known technique in the art to which the present invention pertains, and a detailed description thereof will be omitted.

Next, the injector failure determination step S8b will be described. 3A, the injector failure determination step S8b is a step of determining whether or not the period t coincides with an engine speed by an integer multiple in the period proportion determining step S3, And when the ratio of the variation width h to the output width H is larger than a predetermined reference value (generally, about 0.7), it is determined that the injector system is defective. Here, the 'output width (H)' is the maximum output range of the oxygen sensor signal when the switching fluctuation width (h) indicates the switching period of the oxygen sensor signal proportional to the engine cycle, The maximum output range of the oxygen sensor during the analysis period is defined as "output width (H) ".

Since the injector driving signal is driven once per one cycle of the engine, the switching period of the oxygen sensor signal coincides with the cycle period of the engine. During the one cycle of the engine, each cylinder of the engine is once burned, The switching of the signal indicates that the air-fuel ratio is lean (low fuel) and rich (high fuel), indicating that some cylinders are lean and the rest are rich while the cylinders of the engine are all burning once . That is, it shows that the air-fuel ratio does not match for each cylinder of the engine.

That is, while the oxygen sensor signal switching period (t) exactly coincides with any one of the injector drive signals (I) driving the respective injectors provided in the respective cylinders, as shown in FIG. 3A, 3A, if the ratio (h / H) of the fluctuation width h is larger than the reference width (about 70% or more) as compared with the output width H as shown in FIG. 3A, It can be expected that the air-fuel ratio is poor.

This is because the difference in the air-fuel ratio between each cylinder is significant because the switching hysteresis (h) of the oxygen sensor signal is large. The reason for this situation is that the fuel injected into some cylinders is poor, This is because it can be seen as a case.

In a cylinder equipped with a defective injector, air is normally supplied, but since there is insufficient fuel, a large amount of oxygen remains after the combustion, so that a large amount of oxygen is exhausted from the exhaust gas discharged from the cylinder. Therefore, when the fuel is injected while the air-fuel ratio is rich (when the fuel is larger than the stoichiometric air-fuel ratio), the concentration of oxygen in the exhaust gas becomes low and the oxygen sensor signal becomes high. In this case, When the gas is released, the oxygen sensor signal is lowered, so that the oxygen sensor voltage is lowered every cycle of the engine.

Therefore, the characteristic of the output signal s of the oxygen sensor in this case is that, as shown in FIG. 3A, the switching fluctuation width (t) of the injector drive signal I (h / H) is larger (0.7 times or more) than the reference output value (H). In this case, the reference output value H is an output range of the output signal s of the oxygen sensor during the analysis, and the reference output value H is the output range of the maximum output signal s of the oxygen sensor And has a value in the range of about 0.7 to 0.9 times.

Next, the acceleration / deceleration ratiometric determination step S5 will be described. The acceleration / deceleration ratiometric determination step S5 is a step of determining whether the variation width h is smaller than the output width H (generally, the variation width h / the output width H) (H / H) value is less than or equal to 0.4), the period (t) during the increase and decrease of the engine speed is increased by decreasing the engine speed by increasing and decreasing the engine speed by sequentially instructing the engine to accelerate and decelerate, (R) during the increase and decrease of the engine revolution speed.

In this case, the period t during the increase and decrease of the engine speed in the acceleration / deceleration speed proportional decision step S5 may be the same as the engine speed signal during the increase and decrease of the engine speed r), it is preferable that the valve failure determination step (S8c) is performed.

Further, the period (t) during the increase and decrease of the engine speed in the acceleration / deceleration speed proportioning step S5 may be determined based on the engine speed signal r (S8d), which is determined to be a defect in the intake system, when it is determined that the intake system is defective.

In this case, the small variation width h means that the air-fuel ratios are slightly different for each cylinder of the engine, which means that the air-flow is less than the other cylinders due to the valve failure of some cylinders, Since the distribution of the air introduced from the intake system is not uniformly distributed to the cylinders (this is referred to as "air distribution failure" among the engine development system engineers, it is hereinafter referred to as "air distribution defective"). The air-fuel ratio is lean and the cylinder that enters into less is rich. As a result, it can be predicted that there is a defect of the valve which is a mechanical defect and a defect of air distribution. Therefore, it is determined whether the air fuel ratio between the cylinders continues to be poor while accelerating / decelerating to distinguish the valve. The problem is due to poor air distribution.

This is because, when the air flow rate of the air intake apparatus is changed or the flow rate is changed, inertia and resistance are changed and the air distribution property is changed. Therefore, when the acceleration / deceleration is performed, This is because the air-fuel ratio between the cylinders continues to be defective because the air-fuel ratio is continuously deteriorated without being greatly influenced by the temperature.

Here, the air distribution performance is designed by optimizing the surge tank and the suction system so that air can be uniformly distributed to each cylinder even under various conditions such as flow rate and flow speed temperature in engine development. Through computer simulation, , The minimum sample size is finally determined by the distribution test. Most of the maximum allowable disparity deviation is less than 2.5%. This distribution can be divided into various forms when leakage or inflow of the intake system occurs, or when fluids having different densities such as oil gas or fuel gas are mixed, resulting in severe distribution failure under certain conditions. Therefore, if the inter-cylinder air-fuel ratio error is irregular in the step of determining the proportion of acceleration / deceleration ratios (S5), the direction of the inter-cylinder air-fuel ratio ratio due to the poor air distribution is directed.

Next, the period value determination step (S6) will be described. As shown in FIG. 2, the period value determination step S6 may be performed such that the period t is proportional to the engine speed signal r as shown in FIG. 4, , The period t is compared with the reference period value T to determine the period.

In this case, it is preferable that the ignition system fault determination step (S8e) determines that the ignition system is defective when the period (t) is smaller than the reference period value (T) in the period value determination step (S6) desirable.

If the period t is larger than the reference period value T in the period value determination step S6, a variation with time of the period t is determined as shown in FIG. 2 It is preferable to further perform the period value variation determination step S7.

In this case, a normal determination step (S8f) may be further included to determine whether the variation range of the period (t) with time is similar to the range within the range of 0.3 to 3.0 times in the period value variation determination step (S7) .

If the fluctuation range of the period (t) with respect to time fluctuates beyond the range of 0.3 to 3.0 times in the period value variation determination step (S7), a suction valve And a carbon accumulation check determination step (S8g).

This is because when the period t is in the normal range and the engine is in a normal state but the fluctuation range due to the difference from the preceding and following periods t varies outside the range of the reference (0.3 to 3 times) (Wall film: a film formed by adherence of a fluid component to a wall surface) in which a part of fuel injected from the injector is deposited on carbon, etc., is generated due to a large amount of carbon, etc., This phenomenon may occur when the air-fuel ratio in the combustion chamber becomes excessive due to excessive fuel in the combustion chamber due to excess fuel flowing into the combustion chamber. It is very irregular due to the inner temperature, the negative pressure, the gas velocity and vortex in the combustion chamber.

That is, when the thickness of the wall film becomes thicker, the negative pressure in the intake becomes lower, the temperature inside the intake increases, or the flow rate of the air flowing through the intake becomes faster, the fuel forming the wall film flows into the combustion chamber Fuel ratio injected from the injector is added to the rich air-fuel ratio in the combustion chamber. In the opposite case, the fuel injected from the injector is further accumulated in the wall film, and the state of the air-fuel ratio in the combustion chamber becomes thin. When such a phenomenon occurs, as shown in the waveform of FIG. 4, a lean state or a rich state appears irregularly, and the ratio of the front and rear signal periods t becomes largely different. Therefore, in the case where the front / back ratio of the period (t) of the signal fluctuates so as to deviate from the range (0.3 to 3 times), it can be expected that the excessive accumulation of carbon sludge in the intake valve is caused.

In addition to the above description, when there is no or little carbon sludge in the intake valve, it may occur similar to the situation described above. However, since the formation and disappearance of the wall film are considerably shaped, Can greatly compensate for the lean and rich phenomena. However, since the sludge of the intake valve is excessively accumulated, the thickness, area, and volume of the fuel to be formed by the wall film become very variable and the correction amount is not matched with the result that the air-fuel ratio in the combustion chamber becomes excessively rich or lean. The period of switching of the oxygen sensor varies greatly irregularly.

As a countermeasure against such a wall film, a gasoline direct injection injection (GDI) engine that directly injects fuel into the combustion chamber similar to a diesel engine has been developed and applied. However, unusual richness and lean fuel due to the wall film are rarely observed, When the injected fuel is not sufficiently atomized, the fuel particles interfere with the flame propagation, resulting in a phenomenon similar to ignition failure.

That is, in the case of the GDI engine, ignition system defect determination step (S8e) for determining that the ignition system is defective when the period is smaller than the reference period value (T) in the determination step (S6) of the oxygen sensor period value Quot; ignition system defect or injector fuel atomization defect determination step "which is determined as a defect of the injector fuel atomization or a defect of the injector fuel atomization. Therefore, it is preferable to correspond to the new technology or some exceptional contents in each content description step (S9b to S9g) for displaying the content of the malfunction, the similar malfunction case, and the necessary repair measures in response to the malfunction state .

As shown in FIG. 2, the method for analyzing the engine combustion state using the oxygen sensor signal of the vehicle according to the present invention is performed after the injector failure determination step (S8b) to the intake valve carbon accumulation check determination step (S8g) (S9b to S9g) for displaying the contents of failure, the case of similar failure, and the necessary repair measures in response to the failure state. This is to explain a method for proper maintenance in the process of improving the content and the faulty condition in exceptional cases in the failure determination step.

In addition, a database storing step of storing the results of analysis of each vehicle inspected for each of the injector failure determination step (S8b) to the intake valve carbon accumulation check determination step (S8g) in a database including the history of each vehicle It is preferable to further comprise.

Hereinafter, an engine combustion state inspection and analysis apparatus 100 using an oxygen sensor signal of a vehicle according to an embodiment of the present invention will be described. 5, an apparatus 100 for analyzing an engine combustion state using an oxygen sensor signal of a vehicle according to the present invention includes a sensor input / output connection unit 110, a main control unit 120, a display unit 130, And an operation input unit (140).

First, the sensor input / output connection unit 110 will be described. 5, the sensor input / output connection unit 110 is connected to the sensor signal output unit 20 including the OBD-2 connector 10 of the vehicle, And has a function of receiving the output signal s of the sensor, the engine speed signal r, and each injector drive signal I of each cylinder. In this case, when the speed at which the service data is transmitted to the vehicle is fast enough to determine a situation in which the switching period t of the oxygen sensor signal is proportional to the engine speed, the sensor input / It is preferable to be connected to the sensor signal output unit 20 including the OBD-2 connector 10 of the vehicle as shown in the figure, but it is preferable that the speed at which the service data is transmitted to the vehicle is smaller than the switching period t Is not fast enough to determine a situation proportional to the engine speed, the voltage meter 30 may be used to determine the signal of the oxygen sensor and the number of revolutions of the engine so that some of the injectors It is preferable that the driving signal I and the ignition signal are measured and input.

Usually, in the case of CAN communication, the data transmission speed is sufficiently fast to sufficiently show that the switching cycle of the oxygen sensor is proportional to one cycle of the engine, It can not be seen that the switching period of the oxygen sensor signal is proportional to one cycle of the engine. Therefore, in this case, the oxygen sensor signal and the injector drive signal I and the ignition signal should be measured and input to the engine cylinder of the engine through the voltage meter 30.

Next, the main control device 120 will be described. The main control unit 120 is connected to the sensor input / output connection unit 110 as shown in FIG. 5, and has a function of performing an engine combustion state inspection analysis method using the oxygen sensor signal of the vehicle. The technology for configuring and programming the main control device 120 to have the function of performing the engine combustion state inspection and analysis method using the oxygen sensor signal of the vehicle is well known in the technical field of the present invention, And thus a detailed description thereof will be omitted.

Next, the display unit 130 will be described. As shown in FIG. 5, the display unit 130 is connected to the main control unit 120 and has a function of visually displaying an analysis result of an engine combustion state and a result thereof.

Next, the operation input unit 140 will be described. As shown in FIG. 5, the operation input unit 140 has a function of being connected to the main control device 120 and receiving a user's operation input. The operation input unit 140 may include any one or more of various input means such as a keyboard, a keypad, a mouse, and a tablet.

As shown in FIG. 5, an apparatus 100 for analyzing an engine combustion state using an oxygen sensor signal of a vehicle according to the present invention includes a wireless communication module 150 connected to the main control unit 120, And an external terminal (170) connected to the main control unit (120) using one or more of the oxygen sensor signals . In this case, the external terminal 170 may include any one or more of various devices such as a PDA, a smart phone, a tablet PC, and a notebook computer.

Optimal embodiments have been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: OBD-2 connector 30: voltage meter
100: Analyzer for combustion state of engine using oxygen sensor signal of vehicle
110: Sensor I / O connection
120: Main control device
121: main control unit 122:
123: nonvolatile memory 124: volatile memory
130: display section 140: operation input section
150: wireless communication module 160: internet network
170: External terminal

Claims (5)

A sensor signal input step (S1) for receiving the output signal (s) of the oxygen sensor, the engine speed signal (r), and each injector drive signal (I) of each cylinder;
A period measuring step (S2) of detecting and measuring the period (t) of the output signal (s) of the oxygen sensor;
A period proportion determining step (S3) of determining whether the period (t) measured in the period measuring step (S2) is proportional to either the injector driving signal (I) or the engine speed signal (r);
Determining a fluctuation width (h) of the output signal (s) of the oxygen sensor when the period (t) is proportional to the engine speed signal (r) in the period proportion determining step (S3) );
(T) during the increase and decrease of the engine speed while increasing and decreasing the engine speed by sequentially instructing the engine to accelerate and decelerate when the variation width (h) is smaller than the output width (H) Deceleration ratiometric determination step (S5) for determining whether the engine speed signal r is proportional to the engine speed signal r during the increase and decrease of the engine speed;
If the period t is not proportional to the engine speed signal r in the step S3 of determining the number of revolutions, the cycle value determining step of comparing the period t with the reference period value T (S6);
And the oxygen sensor signal of the vehicle.
The method according to claim 1,
A period value variation determination step (S7) of determining a variation of the period (t) over time when the period (t) is greater than a reference period value (T) in the period value determination step (S6); Further comprising:

In the determination result through the period proportion determining step S3, the switching amplitude determining step S4, the acceleration / deceleration rate determining step S5, the period value determining step S6, and the period value variation determining step S7, follow,

If the period t is equal to any one of the injector driving signals I and the variation width h is larger than the output width H in the period proportion determining step S3, Failure determination step S8b;

Wherein the period t during the increase and decrease of the engine speed in the acceleration / deceleration rate proportioning step S5 is proportional to the engine speed signal r during the increase and decrease of the engine speed A valve defect determination step (S8c) for determining that the valve related defect is present;
Wherein the period t during the increase and decrease of the engine speed in the acceleration / deceleration rate proportioning step S5 is proportional to the engine speed signal r during the increase and decrease of the engine speed (S8d) judging that the intake system is defective;
An ignition system failure determination step (S8e) for determining that the ignition system is defective when the period (t) is smaller than the reference period value (T) in the period value determination step (S6);
A normal determination step (S8f) of determining normal if the fluctuation range of the period (t) with time is similar within a range of 0.8 to 1.2 times in the period value determination step (S7);
If it is determined that the fluctuation range of the period (t) over time is out of the range of 0.8 to 1.2 times in the period value fluctuation determination step (S7), the intake valve carbon accumulation check determination step S8g); Wherein the oxygen sensor signal of the engine is detected by the oxygen sensor signal.
The method according to claim 2,
The sensor signal input step (S1)
Further comprising a filtering step (S1a) of filtering the output signal (s) of the oxygen sensor to remove noise,
Each of the injector failure determination step S8b, the valve defect determination step S8c, the intake defect determination step S8d, the ignition system defect determination step S8e, the normal determination step S8f, and the intake valve carbon accumulation check determination step (S9b to S9g) for displaying the contents of failure, the case of similar failure, and the necessary repair measures in response to the failure state after the step S8g;
A database storage step of storing each vehicle inspected analysis result analyzed for each of the injector failure determination step (S8b) to the intake valve carbon accumulation check determination step (S8g) in a database including the history of each vehicle;
Wherein the oxygen sensor signal of the engine is detected by the oxygen sensor signal.
An apparatus for analyzing an engine combustion state using an oxygen sensor signal of a vehicle performing an engine combustion state inspection analysis method using an oxygen sensor signal of a vehicle according to claim 1,

An output signal s of the oxygen sensor, an engine speed signal r, and an engine speed signal r, which are connected to the sensor signal output unit 20 including the OBD-2 connector 10 of the vehicle, A sensor input / output connection 110 for receiving each injector drive signal I of each cylinder;
A main control unit 120 connected to the sensor input / output connection unit 110 for performing an engine combustion state inspection analysis method using the oxygen sensor signal of the vehicle of claim 1;
A display unit 130 connected to the main control unit 120 and visually displaying an engine combustion state inspection analysis result and a result thereof;
An operation input unit 140 connected to the main control unit 120 and receiving a user's operation input; (100) for analyzing an engine combustion state using an oxygen sensor signal of a vehicle.
The method according to claim 4,
The main control unit 120 is connected to the main control unit 120 by using one or more of the wireless communication module 150 or the internet network 160 to check the engine combustion state using the oxygen sensor signal, An external terminal 170 for inquiring results of the analysis method; (100) for analyzing an engine combustion state using an oxygen sensor signal of a vehicle.

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