KR101806372B1 - Diagnosis Method of the Relative Humidity Sensor for Vehicle - Google Patents

Abstract

The present invention relates to a diagnosis method of a relative humidity sensor for a vehicle and, more specifically, relates to a diagnosis method of a relative humidity sensor for a vehicle, which determines a valid state of a relative humidity value in a current state based on a steam pressure calculation value drawn in a first steam pressure calculation step and a second steam pressure calculation step.

Description

[0001] The present invention relates to a method for diagnosing a relative humidity sensor for a vehicle,

The present invention relates to a method of diagnosing a relative humidity sensor for a vehicle, and more particularly, to a method for diagnosing a fault in a relative humidity sensor for a vehicle, which comprises determining a validity of a relative humidity value in a current state, based on a vapor pressure calculation value derived in a first vapor pressure calculation step and a second vapor pressure calculation step The present invention relates to a fault diagnosis method for a vehicle relative humidity sensor.

The air flow sensor of the vehicle measures the amount of air sucked into the engine, the intake air temperature and the relative humidity, and transmits the frequency signal to the ECU. The ECU controls the EGR amount and the fuel amount using the sensor signal.

In the course of mixing the EGR gas and the fresh air, water condensation may occur depending on the humidity condition inside and outside the vehicle. When the water droplets flow into the components installed in the vehicle or enter the combustion chamber of the engine, Which may lead to breakage of the battery.

For this reason, accurate measurement of relative humidity is recognized as a very important factor in applying EGR. Currently, the condensation water condensation by EGR gas is limited by adjusting the EGR rate according to the measured humidity mainly using the humidity sensor.

Therefore, it is also important to evaluate the soundness of a humidity sensor that accurately measures the humidity on the inside of the vehicle, particularly inside the vehicle, on the line through which the fluid flows.

Up to now, the health evaluation of the humidity sensor has been performed by using the device for determining the consistency of the humidity sensor connected from the outside.

However, the consistency judging device connected from the outside causes variation depending on the mounting position of the sensor and the surrounding environment, and is greatly influenced by disturbance. Accordingly, there is a problem that it is difficult to reliably diagnose the humidity sensor in many cases.

Until now, there has been no apparatus or algorithm for accurately diagnosing a faulty humidity sensor.

Each component installed in the vehicle requires diagnostic items based on the OBD regulations, and it is required to diagnose faults on the circuit abnormality and to check the consistency of the sensor values. In accordance with the OBD regulations, the present invention describes a method for diagnosing a fault of a relative humidity sensor.

The method for diagnosing a relative humidity sensor according to an embodiment of the present invention includes the steps of: (a) performing a preliminary condition check step for performing a relative humidity failure diagnosis, including a reliability checking procedure for a plurality of auxiliary sensors installed in a vehicle, And (b) determining an effective state of the relative humidity value of the current state based on the vapor pressure calculated value.

Here, the relative humidity sensor may be a sensor installed on the outside air inflow path of the vehicle.

According to an embodiment, in the step (a), the plurality of auxiliary sensors includes a plurality of pressure or temperature sensors, and the reliability verification procedure for the plurality of auxiliary sensors includes a step of detecting a deviation between a plurality of pressure sensors, And comparing the deviation between the temperature sensors of the temperature sensor and the predetermined threshold value.

According to an embodiment, in the step (b), the vapor pressure calculation value is derived through a first vapor pressure calculation step for calculating the vapor pressure at the initial start-up and a second vapor pressure calculation step for calculating the vapor pressure after the engine warm-up .

Further, in the calculation of the first vapor pressure and the calculation of the second vapor pressure, the present vapor pressure may be calculated using the calculated saturated vapor pressure stored in the form of table data.

It is further determined whether the absolute value of the difference between the vapor pressure derived in the first vapor pressure calculation step and the vapor pressure derived in the second vapor pressure calculation step is included in the predetermined effective window value range, can do.

In the step (b), it may further include determining whether the failure diagnosis cancellation condition is satisfied,

The method may further include a second verification step of determining whether the relative humidity sensor is normal after the step (b).

Here, the second verification is performed by opening a dump valve installed on the compressor side of the vehicle, recirculating the fluid to the front end of the compressor, and looking at the behavior of the relative humidity sensor at this time.

 INDUSTRIAL APPLICABILITY The method for diagnosing a relative humidity sensor according to the present invention diagnoses the effectiveness of a humidity sensor using sensors mounted on a vehicle in the related art. Therefore, there is no need to diagnose the effectiveness of the humidity sensor through a separate external sensor,

There is an advantage that it is possible to flexibly deal with the necessity of varying the effective range of the relative humidity sensor by adjusting the effective range window value of the vapor pressure in consideration of the current vehicle condition and the surrounding environment.

1 is a schematic view showing an internal combustion engine according to an embodiment of the present invention;
2 is a block diagram of a method for diagnosing a relative humidity sensor failure according to an embodiment of the present invention.
3 is a block diagram illustrating a temperature sensor reliability verification procedure according to an embodiment of the present invention.
4 is a graph showing the rate of change of the relative humidity temperature with the cooling water temperature.
5 is a block diagram of a method for diagnosing a relative humidity sensor failure according to another embodiment of the present invention.

The embodiments described below are provided so that those skilled in the art can easily understand the technical idea of the present invention, and thus the present invention is not limited thereto. In addition, the matters described in the attached drawings may be different from those actually implemented by the schematic drawings to easily describe the embodiments of the present invention.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Means that a feature, number, step, operation, element, component, or combination of features described in the specification is meant to imply the presence of one or more other features, A step, an operation, an element, a component, or a combination thereof.

Also, the expressions such as 'first, second', etc. are used only to distinguish a plurality of configurations, and do not limit the order or other features between configurations. For example, the first and second expressions of the first temperature sensor, the second temperature sensor, the third temperature sensor, the fourth temperature sensor, and the like do not determine the relationship between the structures. However, in the following embodiments, the expressions of 'first' and 'second' in the 'first vapor pressure calculation step' and the 'second vapor pressure calculation step' may mean the order of each step.

As such, the expressions included in the present invention may be interpreted differently according to the embodiment, and therefore, it should be noted that the embodiments described below do not necessarily limit the scope of the present invention.

Before describing the relative humidity sensor for vehicles of the present invention first, a background description of peripheral components will be briefly described with reference to Fig. 1 is a schematic view showing a state of an internal combustion engine according to an embodiment of the present invention.

The combustion chamber of the engine of the present invention has an intake manifold and an exhaust manifold. An intake flow path is connected to the intake manifold. A turbocharger compressor is provided on the intake flow path, and an intercooler and a throttle can be installed downstream of the compressor in the intake flow path. The exhaust manifold is connected to an exhaust passage for exhausting the exhaust gas to the atmosphere. A catalytic device (140) and a muffler (160) are installed downstream of the turbine to clean the exhaust gas. In addition, an exhaust gas recirculation (EGR) system for recirculating a part of the exhaust gas to the intake system may be installed in the exhaust manifold 102 or the exhaust passage 120. The EGR system is typically provided with an EGR cooler for reducing the temperature of the exhaust gas at a high temperature and an EGR valve for controlling the flow rate of the exhaust gas flowing into the EGR passage. In the internal combustion engine of the present invention, both the HP-EGR system and the LP-EGR system can be applied as the EGR system. 1 corresponds to the LP-EGR system. The LP-EGR is branched from the exhaust passage on the upstream side of the muffler 160 and circulates a part of the exhaust gas to the intake system. Here, the exhaust gas recirculation cooler 151 and the exhaust gas And an EGR valve 152 for controlling the gas. The fresh air flowing through the air cleaner 171 flows to the compressor side of the turbocharger via the outside air inflow passage 170 and is mixed with the exhaust gas recirculated through the EGR passage before entering the compressor. The discharge direction of the mixer is opposed to the compressor side.

Next, a fault diagnosis method for a vehicle relative humidity sensor according to an embodiment of the present invention will be described in detail with reference to FIG. 2 to FIG.

2 is a block diagram of a method for diagnosing a relative humidity sensor failure according to an embodiment of the present invention. 3 is a block diagram illustrating a temperature sensor reliability verification procedure according to an embodiment of the present invention. 4 is a graph showing the rate of change of the relative humidity temperature with the cooling water temperature. 5 is a block diagram of a method for diagnosing a relative humidity sensor failure according to another embodiment of the present invention.

The method for diagnosing a relative humidity sensor for a vehicle according to an embodiment of the present invention includes the steps of: (a) determining a reliability condition for a plurality of auxiliary sensors installed in a vehicle except a humidity sensor; And (b) determining an effective state of the relative humidity value of the current state based on the vapor pressure calculated value.

According to one embodiment, the relative humidity sensor may be a sensor installed on the outside air inflow path of the vehicle. Generally, an air flow sensor is provided on the outside air inflow path. The relative humidity sensor may be a separate sensor adjacent to the air amount control sensor. In some cases, the relative humidity sensor may be a sub sensor ) Sensor. That is, in any case, the air amount control sensor of this embodiment is a sensor located on the air amount control sensor side and is located on the outside air inflow path of the vehicle.

In the LP-EGR system, the EGR gas is mixed with fresh air, and in the process of mixing, water condensation may occur depending on the humidity condition, and this water droplet is mixed with each component of the internal combustion engine and the engine cylinder So that the engine can be damaged. Therefore, there is a need to limit the amount of condensate generated through the mixing process of the EGR gas and the outside air through the humidity sensor. The present invention also has an object of diagnosing the humidity sensor from the aspect of health in a state of recognizing such necessity.

The fault diagnosis of the relative humidity can be started when the engine start is completed. When the vehicle is powered on with key on, fault diagnosis can be started. Then, a basic confirmation can be made whether the diagnostic condition is met. The diagnostic condition here may be the basic condition for engine off time, cooling water temperature, and intake temperature.

The fault diagnosis method of the relative humidity will be described in more detail by the steps (a) and (b).

According to an embodiment of the present invention, in the step (a), the plurality of auxiliary sensors may include a plurality of pressure or temperature sensors, and the reliability checking procedure for the plurality of auxiliary sensors may include: Or by comparing the deviation between the plurality of temperature sensors and the magnitude of a predetermined threshold value (the first set value or the first allowable limit value).

The main features of this step are that it includes a pressure or temperature sensor as a plurality of auxiliary sensors and that the deviation between the auxiliary sensors is compared with a reference value (predetermined value) before performing the fault diagnosis method of the full humidity sensor It is.

First, a pressure or temperature sensor may be included as an auxiliary sensor, wherein the pressure or temperature sensor in the vehicle may be provided at various locations. For example, a pressure sensor and a temperature sensor may be installed at the front end of the outside air inflow passage. Pressure sensors may be installed upstream and downstream of the compressor, respectively. A pressure sensor and a temperature sensor may be installed between the intercooler and the throttle valve, and a pressure sensor may be installed downstream of the throttle valve. The pressure sensors and the temperature sensors may be installed at various positions. The plurality of pressure sensors and the temperature sensors are designated and subjected to a reliability verification procedure.

As an example of the reliability checking procedure, a reliability checking procedure for the temperature sensor will be described. 3, the input unit 100 inputs a specific signal to the first temperature sensor 111, the second temperature sensor 112, the third temperature sensor 113, the fourth temperature sensor 114, The output unit 120 receives an output signal output through each sensor. The comparator 130 determines whether the deviation between the plurality of temperature sensors is within a predetermined threshold value (first set value) using the received output signal. If the deviation between the plurality of temperature sensors is smaller than the preset threshold value (the first set value), the procedure proceeds to the full-blown fault diagnosis step (b), and if the deviation between the plurality of temperature sensors is not less than the predetermined threshold value Exit the diagnostic method. If the deviation between the plurality of temperature sensors is not less than the predetermined threshold value, it is not reliable for the temperature sensor, which is an essential preparation element for determining the soundness of the relative humidity.

An example of the above reliability verification procedure can also be applied to pressure sensors.

If the deviation between the plurality of temperature sensors is smaller than a preset threshold value (the first set value or the first allowable limit value), a full-scale fault diagnosis process is performed. The step (b) will be described in detail.

According to an embodiment of the present invention, in the step (b), the vapor pressure calculation value is derived by a first vapor pressure calculation step of calculating a vapor pressure at the initial start-up and a second vapor pressure calculation step of calculating the vapor pressure after the engine warm- .

The vapor pressure calculation can be calculated instantaneously at the current vapor pressure (in hPa units) through the current relative humidity and intake air temperature. For reference, the relative humidity is expressed by the following equation (1).

[Equation 1]

In the first vapor pressure calculation step, the vapor pressure at the time of initial activation of the vehicle (key on) is calculated. The second vapor pressure calculation step refers to a step of calculating the vapor pressure at the time of intake-on rise due to the warm-up of the engine after the initial start of the vehicle and after a certain time has elapsed. Whether or not the engine is warmed up can be confirmed by determining whether the coolant temperature of the vehicle is greater than a predetermined threshold value (second set value).

Referring to FIG. 4, when the atmospheric vapor pressure is constant, the relative humidity value tends to decrease when the intake air temperature rises due to internal warm-up in the engine room. At this time, the vapor pressure (vapor pressure by the first vapor pressure calculation step) calculated at the time of initial startup is compared with the vapor pressure (vapor pressure by the second vapor pressure calculation step) calculated after warm-up. In FIG. 4, P1 and P2 mean that the relative humidity values are calculated at each time point. In the present invention, the first and the second points, which are the bases, Even if only the change between the second point after the past is examined, there is an advantage that the fault diagnosis of the relative humidity sensor can be performed.

On the other hand, the relative humidity can be calculated by designating the saturated water vapor pressure through the table of the previously prepared saturated water vapor pressure and substituting the measured present water vapor pressure into the above equation (1). 2 In the vapor pressure calculation step, the present vapor pressure can be calculated using the saturated vapor pressure calculation value stored in the form of table data.

According to one embodiment, in calculating the vapor pressure, the variable of variation of the vapor pressure may be confirmed (S122). Confirmation of the vapor pressure is to identify factors that may cause the vapor pressure to change, such as an increase in vehicle speed, thereby ensuring the reliability of the calculated vapor pressure.

Referring to FIG. 4, there is an indication for range R at the bottom. The effective window value is used as a criterion for determining whether or not the relative humidity sensor is faulty. The vapor pressure by the first vapor pressure calculation step and the second vapor pressure calculation It can be determined that the relative humidity sensor is in the normal category when the difference of the vapor pressure value by the step is included in the effective window value. In other words, according to one embodiment of the present invention, it is determined whether the absolute value of the difference between the vapor pressure derived in the first vapor pressure calculation step and the vapor pressure derived in the second vapor pressure calculation step is included in the predetermined effective window value range Thereby determining whether the relative humidity sensor is malfunctioning or not.

In some cases, the validity range can be flexibly secured by adjusting the range of the effective window value (third set value) in consideration of the current vehicle condition and the surrounding environment.

As another example, the step (b) may further include determining whether the failure diagnosis cancellation condition is satisfied as shown in FIG.

The fault diagnosis cancellation condition is to check individually whether the vehicle windshield wiper is operating, whether the vehicle is at a high altitude and whether other sensors are faulty, so that the wiper operates or is located at a high altitude or If the sensor is faulty, it means that the fault diagnosis is stopped and the procedure is terminated. For example, in the case where the wiper of the vehicle front glass is operated, it can be predicted that it is in a rainy state, and accordingly, it is not preferable to perform the failure diagnosis method because the humidity sensor is saturated. Even when the vehicle is located at a high altitude, the flow rate of the air is small and the humidity change of the relative humidity may be different from that of the ground surface. The embodiments related to the fault diagnosis cancellation condition of the present invention are not limited to the embodiments described above, and more various embodiments may fall within the scope of the present invention.

If the absolute value of the difference between the start-time vapor pressure (the vapor pressure of the first vapor pressure calculation step) and the vapor pressure after the warm-up (or the warm-up time also corresponds to the vapor pressure of the second vapor pressure calculation step) It can be determined that the relative humidity sensor is normal. If the absolute value of the difference between the vapor pressure at the time of starting and the vapor pressure after warming is not smaller than the predetermined window value, it can be determined that the relative humidity sensor is faulty. The result of the judgment can be displayed on the display or the instrument panel near the center fascia of the vehicle to provide information to the driver.

Further, according to an embodiment of the present invention, after the step (b), it may further include a secondary verification step of determining whether the relative humidity sensor is normal.

Specifically, the secondary verification may be performed by opening the dump valve 180 installed on the compressor side of the vehicle, recirculating the fluid to the front end of the compressor, and looking at the behavior of the relative humidity sensor at this time. When the dump valve 180 is opened, the mixture of the EGR gas and the outside air at the rear end of the compressor is recirculated back to the front end of the compressor. At this time, the integrity of the humidity sensor can be evaluated by confirming the behavior of the humidity sensor again.

For reference, reference numerals S111 to S114 shown in FIG. 2 may correspond to the step (a) of the present invention, and reference numerals S121 to S126 may correspond to the step (b) of the present invention.

In the fault diagnosis method of the present invention, it is determined whether the diagnosis condition for fault diagnosis is satisfied (S112), whether the deviation between the auxiliary sensors is smaller than the threshold value (S114), whether the diagnosis cancellation condition is detected (S123). If the condition is not satisfied in the process of determining whether the engine is warmed up (S124), the process may immediately end in the failure diagnosis process.

According to the present invention, there is no need to diagnose the effectiveness of the humidity sensor through a separate external sensor because the diagnostic method of the relative humidity sensor diagnoses the effectiveness of the humidity sensor using the sensors mounted on the vehicle. ,

There is an advantage that it is possible to flexibly deal with the necessity of varying the effective range of the relative humidity sensor by adjusting the effective range window value of the vapor pressure in consideration of the current vehicle condition and the surrounding environment.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: input unit 152: LP-EGR valve
111, 112, 113, 114: a temperature sensor 160: a muffler
120: output unit 171: air cleaner
130: comparator 172: differential pressure valve
140: catalytic converter 180: dump valve
150: LP-EGR Euro
151: LP-EGR cooler

Claims (9)

A fault diagnosis method for a vehicle relative humidity sensor,
(a) a preliminary condition check step for performing a relative humidity trouble diagnosis, including a reliability checking procedure for a plurality of auxiliary sensors installed in a vehicle other than the humidity sensor;
(b) determining an effective state of the relative humidity value in the current state based on the vapor pressure calculated value.
The method according to claim 1,
Wherein the relative humidity sensor is a sensor installed on the outside air inflow path of the vehicle.
The method according to claim 1,
In the step (a)
Wherein the plurality of auxiliary sensors comprise a plurality of pressure or temperature sensors,
The reliability checking procedure for the plurality of auxiliary sensors includes:
And comparing the deviation between a plurality of pressure or temperature sensors and a predetermined threshold value.
The method according to claim 1,
In the step (b)
Wherein the vapor pressure calculation value is derived through a first vapor pressure calculation step for calculating the vapor pressure at the initial start and a second vapor pressure calculation step for calculating the vapor pressure after the engine warm-up.
5. The method of claim 4,
Wherein the current vapor pressure is calculated using the saturated vapor pressure calculation value stored in the form of table data in the first vapor pressure calculation step and the second vapor pressure calculation step.
5. The method of claim 4,
Determining whether the absolute value of the difference between the vapor pressure derived in the first vapor pressure calculation step and the vapor pressure derived in the second vapor pressure calculation step is included in the predetermined effective window value range and determining whether the relative humidity sensor is faulty Wherein the relative humidity of the vehicle is measured.
The method according to claim 1,
In the step (b)
Further comprising the step of determining whether or not the failure diagnosis cancellation condition is satisfied.
The method according to claim 1,
After the step (b)
Further comprising a second verification step of determining whether the relative humidity sensor is normal or not.
9. The method of claim 8,
Wherein the secondary verification is performed by opening a dump valve provided on the compressor side of the vehicle to recirculate the fluid to the front end of the compressor and checking the behavior of the relative humidity sensor at this time.

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