JP6844276B2 - Judgment device - Google Patents

Description

The present invention relates to a determination device for determining a failure of a humidity sensor that measures the humidity of intake air sucked into an internal combustion engine for a vehicle.

In recent years, there has been an increasing demand for measuring the humidity of intake air for the purpose of improving fuel efficiency of internal combustion engines and cleaning exhaust gas.
As a humidity sensor for measuring the humidity of the intake air, the one having the following configuration is known.
The humidity sensor has a humidity sensitive film existing in the intake passage through which the intake air sucked into the internal combustion engine of the vehicle flows, and has a humidity detection unit that outputs the relative humidity of the intake air from the capacitance of the humidity sensitive film. It is provided with a temperature detection unit that detects the temperature of the wet film and outputs the temperature, and a heating unit that heats the humidity sensitive film. Then, the humidity sensitive film is constantly heated by the heating unit to suppress dew condensation and fouling of the moisture sensitive film, thereby maintaining the humidity detection accuracy (see, for example, Patent Document 1).

Here, as a factor that deteriorates the humidity detection accuracy, not only dew condensation and fouling of the humidity sensitive film but also a failure of the humidity detection unit itself can be considered.
However, the humidity sensor of Patent Document 1 is not configured to detect a failure of the humidity sensor itself.

Since the humidity sensor of Patent Document 1 has a configuration in which the humidity detection unit and the temperature detection unit are continuously heated by the heating unit, the temperature of the temperature detection unit rises and the detection accuracy of the temperature of the intake air deteriorates. It ends up. Further, as the temperature of the humidity detection unit rises, the temperature of the humidity-sensitive film also rises, which leads to a decrease in the detection accuracy of the absolute humidity (see FIG. 10). Further, since the heating portion is continuously heated, the power consumption also increases.

Japanese Unexamined Patent Publication No. 2015-87196

The present invention has been made in view of the above problems, and an object of the present invention is to provide a determination device capable of detecting a failure of a humidity sensor having a humidity sensitive film existing in an intake passage.

The determination device of the present invention has a humidity sensitive film existing in the intake passage through which the intake air sucked into the internal combustion engine of the vehicle flows, and the humidity detection that outputs the relative humidity of the intake air from the capacitance of the humidity sensitive film. A failure of a humidity sensor including a unit, a temperature detection unit that detects the temperature of the humidity-sensitive film and outputs the temperature, and a heating unit that heats the humidity-sensitive film is determined.

Further, the heating portion is arranged on the back surface side of the moisture-sensitive film , and the temperature of the humidity-sensitive film rises when it is heated by the heating portion.
Here, the temperature detected at a predetermined time is the original temperature, the relative humidity at the original temperature is the original relative humidity, and the temperature different from the original temperature detected after heating by the heating unit or after the heating is stopped by the heating unit is the post-temperature. , And the relative humidity at the post-temperature is referred to as the post-relative humidity.

Then, a failure determination unit for determining a failure of the humidity detection unit is provided by comparing the estimated value of the relative humidity at the rear temperature estimated from the original relative humidity and the rear temperature with the rear relative humidity.
In addition, an abnormality determination unit that determines whether or not the detected value is abnormal by comparing the estimated relative humidity at the post-temperature with the post-relative humidity, and the original relative humidity and the original relative humidity when the abnormality determination unit determines that the value is abnormal. A predetermined condition when the humidity determination unit that determines whether or not both the rear relative humidity are equal to or higher than the predetermined relative humidity and the humidity determination unit determines that both the original relative humidity and the posterior relative humidity are equal to or higher than the predetermined relative humidity. It has a condition determination unit for determining whether or not the condition is satisfied.
Here, the predetermined condition is that the temperature of the intake air is equal to or higher than the predetermined temperature .

As a result, the estimated value of the relative humidity at the post-temperature is compared with the actual post-relative humidity, and for example, if the difference between the two values is larger than a predetermined value, it can be determined that the humidity detection unit has failed. ..
Therefore, it is possible to detect a failure of the humidity detection unit having a humidity sensitive film existing in the intake passage.
The temperature output by the temperature detection unit includes an electric signal such as a voltage value that can be converted into a temperature.
Similarly, the relative humidity output by the humidity detector includes an electrical signal that can be converted to relative humidity, such as a voltage value.

It is an intake / exhaust system of an internal combustion engine for a vehicle (Example). It is sectional drawing of (a) humidity sensor and flow rate sensor seen from the upstream side of the intake air flow, and (b) the flow rate sensor along the flow direction of intake air (Example). It is explanatory drawing of the moisture-sensitive film (Example). It is a perspective view of a humidity sensor (Example). It is sectional drawing of the humidity sensor along the VV line in FIG. 4 (Example). It is a flow chart which shows the control method of the determination apparatus (Example). It is explanatory drawing of the method of obtaining the estimated value of the relative humidity at the post-temperature using a psychrometric chart (Example). (A) is an explanatory diagram of a change in relative humidity before and after heating in a normal state, and (b) is an explanatory diagram of a change in relative humidity before and after heating in an abnormal state (Example). (A) is an explanatory diagram of a change in relative humidity before and after heating in a normal state, and (b) is an explanatory diagram of a change in relative humidity before and after heating in the case of dew condensation (Example). It is explanatory drawing of the accuracy of the temperature and absolute humidity of a humidity sensitive film using a psychrometric chart (Example). It is explanatory drawing of the original temperature and the post temperature (Example). It is explanatory drawing of the original temperature and the post temperature (modification example).

Hereinafter, embodiments for carrying out the invention will be described with reference to examples. It should be noted that the examples disclose a specific example, and it goes without saying that the present invention is not limited to the examples.

[Structure of Examples]
First, the intake / exhaust system of the internal combustion engine 2 for a vehicle in which the humidity measuring device 1 is incorporated will be described with reference to FIG. Here, the humidity measuring device 1 has a humidity sensor 3 and a determining device 5, which will be described later.

The internal combustion engine 2 includes an intake passage 6 that guides intake air to a cylinder and an exhaust passage 7 that exhausts exhaust gas generated in the cylinder to the atmosphere.
The intake passage 6 is composed of internal passages of an intake pipe, an intake manifold, and an intake port.
The intake pipe is a passage member from the intake of outside air to the intake manifold. The intake pipe includes an air cleaner 8 for removing dust and dirt contained in the intake air, a humidity sensor 3 for measuring the humidity of the intake air, and the like. A flow rate sensor 9 for measuring the flow rate of intake air, a throttle valve 10 for adjusting the amount of intake air sucked into the cylinder, and the like are provided.
Further, an intake pressure sensor 11 for measuring the pressure of the intake air is arranged on the downstream side of the throttle valve 10 of the intake passage 6.

The intake manifold is a distribution pipe that distributes the intake air supplied from the intake pipe into each cylinder of the internal combustion engine 2.
The intake port is formed for each cylinder in the cylinder head of the internal combustion engine 2, and guides the intake air distributed by the intake manifold into the cylinder.

The exhaust passage 7 is composed of an exhaust port, an exhaust manifold, and internal passages of an exhaust pipe.
Like the intake port, the exhaust port is formed for each cylinder in the cylinder head of the internal combustion engine 2 and guides the exhaust gas generated in the cylinder to the exhaust manifold.
The exhaust manifold is a collecting pipe for exhaust gas discharged from each exhaust port.
Further, an air-fuel ratio sensor 12 for measuring the concentration of oxygen in the exhaust gas is arranged in the exhaust passage 7.

The cylinder head in which the intake port and the exhaust port are formed is provided with an intake valve that opens and closes the outlet end of the intake port and an exhaust valve that opens and closes the inlet end of the exhaust port for each cylinder.

Here, the operating state of the internal combustion engine 2 is controlled by an electronic control unit (hereinafter, referred to as an ECU 13).
The ECU 13 receives signals from various sensors that detect parameters indicating the operating state and control state of the internal combustion engine 2. Further, the ECU 13 has an input circuit that processes the input signal, a CPU that performs control processing and arithmetic processing related to the control of the internal combustion engine 2 based on the input signal, data and programs necessary for controlling the internal combustion engine 2. It is provided with various memories to be stored and held, an output circuit for outputting a signal necessary for controlling the internal combustion engine 2 based on the processing result of the CPU, and the like.

In addition to the humidity sensor 3, the flow rate sensor 9, the intake pressure sensor 11, and the air fuel ratio sensor 12, the various sensors that output signals to the ECU 13 include an oil temperature sensor 14 that detects the temperature of the hydraulic oil of the internal combustion engine 2. A rotation speed sensor 15 and the like for detecting the rotation speed of the internal combustion engine 2 are included.
Then, based on these signals, the ECU 13 controls the throttle valve 10 to increase or decrease the flow rate of the intake air, or controls the fuel injection valve 16 for injecting fuel to increase or decrease the fuel injection amount to the internal combustion engine 2. The operating state of the internal combustion engine 2 is controlled by making the internal combustion engine 2 operate.
Further, the ECU 13 has a determination device 5 which will be described in detail later.

The humidity sensor 3 and the flow rate sensor 9 of the embodiment will be described in detail with reference to FIG.
The flow rate sensor 9 is arranged in the intake passage 6.
Hereinafter, the direction in which the intake air flows in the intake passage 6 may be referred to as the direction F.

The flow rate sensor 9 holds the flow rate sensor chip 17 and projects to the inner circumference of the intake passage 6 to detect the flow rate of the intake air.
The flow rate sensor 9 is provided of a resin material, and a passage is formed inside.
The structure of the passage formed inside the flow rate sensor 9 includes, for example, a bypass passage 18 and a sub-bypass passage 19.

The bypass passage 18 is a passage through which a part of the intake air flowing through the intake passage 6 flows, and the passage is formed along the direction F. Then, the intake port 18a is provided on the upstream side of the bypass passage 18, and the discharge port 18b is provided on the downstream side of the bypass passage 18.
On the downstream side of the bypass passage 18, a discharge port throttle 18c that throttles the flow of intake air passing through the bypass passage 18 is formed.

The sub-bypass passage 19 has an inlet 19a into which a part of the intake air flowing through the bypass passage 18 throttled by the discharge port throttle 18c flows in, and an outlet 19b for returning the intake air passing through the sub-bypass passage 19 to the intake passage 6. Be prepared. Then, the intake air flowing in from the inlet 19a is made a U-turn inside the flow rate sensor 9 and guided to the outlet 19b.

The flow rate sensor chip 17 has a flow rate detection unit that outputs a flow rate, and the flow rate detection unit has a flow rate detection element 20 that is sensitive to the flow rate of intake air. Here, the flow rate detection element 20 is a heat transfer type that measures the flow rate by heat transfer of the intake air passing through the inside of the sub-bypass passage 19, and has a well-known configuration having a heat generation resistor and a resistance temperature detector on the surface. It has become.
The flow rate output by the flow rate detection unit includes an electric signal such as a voltage value that can be converted into a flow rate.

The humidity sensor 3 holds the humidity sensor chip 21 and protrudes from the flow sensor 9 to the inner circumference of the intake passage 6 to detect the humidity of the intake air.
When the protruding direction is the longitudinal direction, the humidity sensor 3 projects so that the longitudinal direction is orthogonal to the direction F.
The humidity sensor chip 21 has, for example, a humidity sensitive film 22 that is sensitive to the humidity of the intake air. Here, the humidity sensor chip 21 has a humidity-sensitive film 22 on its surface, and is held by the humidity sensor 3 so that the humidity-sensitive film 22 is exposed to the intake passage 6. More specifically, the humidity sensor chip 21 is held so that the surface of the moisture sensitive film 22 is parallel to the longitudinal direction and parallel to the direction F.

The humidity sensor chip 21 is, for example, a capacitance type in which the capacitance of the humidity sensitive film 22 changes according to humidity, and outputs relative humidity. The moisture-sensitive film 22 is a polymer film, and its own capacitance changes as the amount of water molecules taken in changes according to the ambient humidity.
More specifically, as shown in FIG. 3, in the sensor chip 21, the capacitance value detected between the electrodes is increased by allowing water molecules to enter the humidity-sensitive film 22 in an amount corresponding to the ambient humidity. It has a changing structure. The dotted line in the figure represents an electric line of force.

Here, the humidity sensor 3 and the flow rate sensor 9 are both connected to the base 23. That is, the base portion 23 is formed so as to be the root of the protrusion of the humidity sensor 3 and the flow rate sensor 9. The base portion 23 is formed by accommodating the end portions of the humidity sensor 3 and the flow rate sensor 9 in the mold and injecting the molten resin into the mold.

Further, in the intake passage 6, a mounting hole that penetrates the inside and outside of the intake passage 6 is formed at a position where the humidity sensor 3 and the flow rate sensor 9 are mounted. Then, the base portion 23 is fitted into the mounting hole and fixed to the intake passage 6, so that the humidity sensor 3 and the flow rate sensor 9 are fixed to the intake passage 6.
Further, a connector 25 is provided on the base 23, and signals of flow rate and relative humidity are output from the terminals in the connector 25. Here, the flow rate and the relative humidity are output from the same terminal.

Here, as shown in FIG. 4, the humidity sensor 3 is connected to the humidity sensor chip 21, the circuit board 33 made of FPC on which the humidity sensor chip 21 is mounted, and the terminals of the circuit board 33 by wire bonding, and the lead frame 34a. It has ~ 34d and is entirely molded by the resin member 35.
Here, the lead frame 34b has a mounting portion 36 on which the circuit board 33 is mounted at the end portion. Then, the end portion of the lead frames 34a to 34d different from the mounting portion 36, the surface of the mounting portion 36 on the side where the circuit board 33 is not mounted, and the humidity sensitive film 22 of the humidity sensor chip 21 are exposed from the resin member 35. doing.
Since the mounting portion 36 is partially exposed from the resin member 35 to the intake air passage 6 and exposed to the intake air, the temperature of the humidity sensor chip 21 is also substantially equal to the temperature of the intake air.

The ends of the lead frames 34a to 34d on different sides from the mounting portions 36 are electrically connected to the terminals in the connector 25, respectively. The lead frames 34a to 34d excluding the mounting portion 36 are embedded in the base portion 23.
Here, the lead frame 34a is connected to a DC power supply, and the lead frame 34b is grounded. Then, the lead frames 34c and 34d exchange data signals with the ECU 13 according to, for example, the I2C protocol.

Here, as shown in FIG. 5, the humidity sensor chip 21 has a humidity detection unit 37, a temperature detection unit 39, and a heating unit 40.
The humidity detection unit 37 includes a humidity sensitive film 22 and a relative humidity output unit 41 that detects relative humidity from the capacitance of the humidity sensitive film 22 and outputs a voltage signal corresponding to the relative humidity.
The temperature detection unit 39 includes a temperature measuring unit 42 that detects the temperature of the humidity sensitive film 22, and a temperature output unit 43 that detects the temperature from the signal of the temperature measuring unit 42 and outputs a voltage signal corresponding to the temperature.
Then, the heating unit 40 provided in the vicinity of the moisture-sensitive film 22 heats the moisture-sensitive film 22.

The humidity sensor chip 21 is driven by the voltage of the DC power supply via the lead frames 34a and 34b, outputs a signal such as relative humidity according to the command signal of the ECU 13 via the lead frames 34c and 34d, and is output by the heating unit 40. The humidity sensitive film 22 is heated.

[Characteristics of Examples]
Next, the characteristic configuration of the embodiment will be described.
The humidity measuring device 1 of the embodiment has a determination device 5.
Then, the determination device 5 includes a temperature rise command unit 44 that raises the temperature of the humidity sensitive film 22 by the heating unit 40, an estimated value of the relative humidity at the post temperature estimated from the original relative humidity and the post temperature, and the post. A failure determination unit 45 for determining a failure of the humidity detection unit 37 by comparing with the relative humidity is provided (see FIG. 1).
Here, the temperature detected before the temperature rise of the humidity sensitive film 22 by the heating unit 40 is the original temperature, the relative humidity at the original temperature is the original relative humidity, and the temperature detected after the temperature rise of the moisture sensitive film 22 by the heating unit 40 is detected. The temperature is the post-temperature, and the relative humidity at the post-temperature is the post-relative humidity.

The original temperature and the post-temperature may be the temperatures in the constant temperature state before and after the temperature rise as shown in FIG. 11 (a), or the temperature during the temperature rise as shown in FIG. 11 (b). Good.
The black circles in the figure indicate the time when the original temperature and the post temperature are detected.

Further, the failure determination unit 45 determines the failure when the other device is not controlled based on the relative humidity.
Further, after the failure determination unit 45 determines the failure and the temperature reaches the original temperature, the other device is controlled based on the relative humidity.

Further, the determination device 5 includes an abnormality determination unit 46, a humidity determination unit 47, a condition determination unit 48, and an integration number determination unit 49 described below (see FIG. 1).
The abnormality determination unit 46 determines whether or not the detected value of the relative humidity is abnormal by comparing the estimated value of the relative humidity at the post-temperature with the post-relative humidity.
The humidity determination unit 47 determines whether or not both the original relative humidity and the rear relative humidity are 90% or more when the abnormality determination unit 46 determines that the abnormality is present.
The condition determination unit 48 determines whether or not the predetermined condition is satisfied when the humidity determination unit 47 determines that both the original relative humidity and the rear relative humidity are 90% or more.
Here, the predetermined condition is a condition in which the temperature of the intake air is 30 degrees or higher and the temperature of the hydraulic oil of the internal combustion engine 2 is 80 degrees or higher.
When the condition determination unit 48 determines that the predetermined condition is satisfied, the integration number determination unit 49 increases the integration number by 1 and determines whether or not the integration number exceeds 5.

Further, the failure determination unit 45 does not determine the failure when the temperature of the intake air is 10 degrees or less.
Further, the determination device 5 outputs a signal for operating the notification unit 50 when it is determined to be a failure (see FIG. 1).

[Control method of the embodiment]
A specific example of the control method of the determination device 5 of the embodiment will be described with reference to the flow chart of FIG.
First, in step S100, it is determined whether or not the temperature of the intake air is higher than 10 degrees.
If the temperature of the intake air is higher than 10 degrees (YES), the process proceeds to step S110.
When the temperature of the intake air is 10 degrees or less (NO), the process is terminated.
The temperature of the intake air is the temperature output by the temperature detection unit 39.

Next, in step S110, it is determined whether or not the relative humidity is used for controlling another device. Here, the other device is, for example, a throttle valve 10 or a fuel injection valve 16.
If it is determined that the relative humidity is being used to control another device (YES), the process ends.
When it is determined that the relative humidity is not used for controlling other devices (NO), the process proceeds to step S120.

Here, the time when the relative humidity is not used for controlling other devices is, for example, when the humidity detection unit 37 is energized, when the vehicle is decelerated, or when the vehicle is stopped.
When the humidity detection unit 37 is energized, it is before the control of the internal combustion engine 2 is started using the relative humidity, and the relative humidity is not used for controlling other devices. Further, when the vehicle is decelerated, the supply of fuel to the internal combustion engine 2 is interrupted, so that the internal combustion engine 2 is not controlled using the relative humidity, and the relative humidity is used for controlling other devices. Not. Even when the vehicle is stopped, the relative humidity is not used to control other devices.

Next, in step S120, the humidity sensor chip 21 outputs the relative humidity and temperature to the ECU 13 as the determination device 5, and the ECU 13 stores the relative humidity and temperature in its own memory or the like as the original relative humidity and the original temperature. , Step S130.

Next, in step S130, the temperature of the moisture-sensitive film 22 is raised by the heating unit 40.
It should be noted that raising the temperature of the moisture-sensitive film 22 by the heating unit 40 is not limited to the case where the humidity-sensitive film 22 shifts from the state where it is not heated by the heating unit 40 to the state where it is heated. This includes a case where 22 is shifted from a state in which it is preheated by the heating unit 40 to a state in which it is further heated.
The step S130 corresponds to the function of the temperature rise command unit 44.
Then, the process proceeds to step S140.

Next, in step S140, the humidity sensor chip 21 outputs the relative humidity and temperature to the ECU 13 as the determination device 5, and the ECU 13 stores the relative humidity and temperature in its own memory or the like as the post-relative humidity and post-temperature. , Step S150.

Next, in step S150, it is determined whether or not the detected value of the relative humidity is abnormal by comparing the estimated value of the relative humidity at the post-temperature estimated from the original relative humidity and the post-temperature with the post-relative humidity. judge.
Note that step S150 corresponds to the function of the abnormality determination unit 46.

More specifically, by using the psychrometric chart shown in FIG. 7, the absolute humidity amount can be calculated first from the original relative humidity. For example, when the original temperature is 25 degrees and the original relative humidity is 50%, the absolute humidity is 10 g / kg. Since the absolute humidity does not change even when the humidity sensitive film 22 is heated, the relative humidity value at the post-temperature can be estimated from the psychrometric chart. For example, when the post-temperature is 35 degrees and the absolute humidity is 10 g / kg, the estimated relative humidity is 28.3%. Then, it is determined whether or not the detection value of the humidity detection unit 37 is abnormal depending on whether or not the estimated value of the relative humidity at the post-temperature and the post-relative humidity substantially match (see FIG. 8). The arrows in the figure represent changes in relative humidity corresponding to the temperature changes in FIG. 8 (a).
The psychrometric chart is stored in advance in the memory of the ECU 13 as a data set or a calculation formula.

If it is determined that the detected value is abnormal (YES) (see the dotted line in FIG. 8B), the process proceeds to step S160.
When it is determined that the detected value is not abnormal (NO) (see FIG. 8A), the process proceeds to step S230, and the temperature rise of the moisture-sensitive film 22 by the heating unit 40 is stopped. Then, the process proceeds to step S240, and the process ends after waiting until the temperature of the moisture-sensitive film 22 detected by the temperature detection unit 39 reaches the original temperature.
After the processing is completed, other devices can be controlled based on the relative humidity.
Note that FIGS. 8 (a) and 8 (b) show the time changes of the original temperature, the original relative humidity, and the post-temperature and the post-relative humidity before and after the temperature rise of the moisture-sensitive film 22, respectively.

Next, in step S160, it is determined whether or not the original relative humidity and the post-relative humidity are 90% or more.
When it is determined that the original relative humidity and the post-relative humidity are 90% or more (YES) (see FIG. 9B), the process proceeds to step S170.
If it is determined that the post-relative humidity is less than 90% (NO) (see FIG. 9A), the process proceeds to step S200.
Step S160 corresponds to the function of the humidity determination unit 47.
Note that FIGS. 9 (a) and 9 (b) show the time changes of the original temperature, the original relative humidity, and the post-temperature and the post-relative humidity before and after the temperature rise of the moisture-sensitive film 22, respectively.

Next, in step S170, it is determined whether or not the condition that the temperature of the intake air is 30 degrees or higher and the temperature of the hydraulic oil of the internal combustion engine 2 is 80 degrees or higher is satisfied.
When it is determined that the temperature of the intake air is 30 degrees or higher and the temperature of the hydraulic oil of the internal combustion engine 2 is 80 degrees or higher (YES), the process proceeds to step S180.
When it is determined that the temperature of the intake air is 30 degrees or higher and the temperature of the hydraulic oil of the internal combustion engine 2 does not satisfy the conditions of 80 degrees or higher (NO), the process proceeds to step S230, and the humidity sensitive film formed by the heating unit 40 is formed. The temperature rise of 22 is stopped. Then, the process proceeds to step S240, and the process ends after waiting until the temperature of the moisture-sensitive film 22 detected by the temperature detection unit 39 reaches the original temperature.
Note that step S170 corresponds to the function of the condition determination unit 48.

Next, in step S180, the number of integrations is increased by 1 and the process proceeds to step S190.
Next, in step S190, it is determined whether or not the number of integrations exceeds 5.
If it is determined that the number of times of integration exceeds 5 (YES), the process proceeds to step S200 to determine a failure, the process proceeds to step S210, the temperature rise of the moisture-sensitive film 22 by the heating unit 40 is stopped, and then the process proceeds to step S220. To do. Then, in step S220, a signal for operating the notification unit 50 is output. In addition, step 150 and step S200 correspond to the function of the failure determination unit 45.
When it is determined that the number of integrations is 5 or less (NO), the process proceeds to step S230, and the temperature rise of the moisture-sensitive film 22 by the heating unit 40 is stopped. Then, the process proceeds to step S240, and the process ends after waiting until the temperature of the moisture-sensitive film 22 detected by the temperature detection unit 39 reaches the original temperature.
In addition, step S180 and step S190 correspond to the function of the integration number determination unit 49.

[Effect of Examples]
The determination device 5 of the embodiment is a failure determination unit that determines a failure of the humidity detection unit 37 by comparing the estimated value of the relative humidity at the post-temperature estimated from the original relative humidity and the post-temperature with the post-relative humidity. 45 is provided.

As a result, the estimated value of the relative humidity at the post-temperature is compared with the actual post-relative humidity, and for example, if the difference between the two values is larger than the predetermined value, it is determined that the humidity detection unit 37 has failed. it can.
Therefore, it is possible to detect a failure of the humidity detection unit 37 having the humidity sensitive film 22 existing in the intake passage 6.

According to the determination device 5 of the embodiment, the failure determination unit 45 determines the failure when the other device is not controlled based on the relative humidity.
As a result, the temperature of the moisture-sensitive film 22 does not rise because the heating unit 40 of the moisture-sensitive film 22 does not heat the moisture-sensitive film 22 when controlling other devices. Therefore, the accuracy of the absolute humidity calculated from the psychrometric chart can be ensured.

Here, the reason why the accuracy of the absolute humidity becomes worse when the absolute humidity is obtained from the relative humidity by using the psychrometric chart will be described with reference to FIG. 10 as the temperature of the humidity sensitive film 22 becomes higher.
For example, the fluctuation range of the absolute humidity corresponding to the fluctuation range of 3% above and below the relative humidity of 70% when the temperature of the humidity sensitive film 22 is 30 degrees is 18.3 to 19.7 g / kg. When the temperature is 30 degrees and the relative humidity is 70%, the absolute humidity is 18.8 g / kg.
On the other hand, when the temperature of the humidity sensitive film 22 is 50 degrees and the absolute humidity is 18.8 g / kg, the fluctuation range of the absolute humidity corresponding to the fluctuation range of 3% above and below the relative humidity is 16.4 to 21.3 g / kg. It has become.

That is, the higher the temperature of the humidity sensitive film 22, the larger the amount of deviation of absolute humidity with respect to the deviation of relative humidity of 1%.
Therefore, the lower the temperature of the humidity sensitive film 22, the better the accuracy of the absolute humidity that can be obtained from the psychrometric chart.
It should be noted that the heating by the heating unit 40 of the moisture-sensitive film 22 is performed only at the time of determining a failure, and is not constant heating, so that the power consumption can be reduced.

According to the determination device 5 of the embodiment, after the failure determination unit 45 determines the failure and the temperature reaches the original temperature, the other device is controlled based on the relative humidity.
As a result, after the temperature of the humidity sensitive film 22 returns to the original temperature, other devices are controlled, so that the accuracy of the absolute humidity calculated from the psychrometric chart can be further ensured.
Further, the other device may be controlled after the relative humidity returns to the original relative humidity. In this case, the time required for the relative humidity to return to the original relative humidity is longer than the time required for the temperature to return to the original temperature. However, the accuracy of absolute humidity can be further ensured.

According to the determination device 5 of the embodiment, the humidity sensor 3 has a humidity sensor chip 21 having a humidity detection unit 37, and also has a heating unit 40.
This eliminates the need to provide a heating unit 40 separately from the humidity sensor chip 21.
Further, the humidity sensor chip 21 has a temperature detection unit 39.
As a result, the temperature measuring unit 42 can be provided in the vicinity of the humidity sensitive film 22, so that the temperature of the moisture sensitive film 22 can be detected more accurately.
Since the temperature measuring unit 42 and the humidity sensitive film 22 are close to each other, it is possible to suppress a time delay in detecting a temperature rise due to heating. Therefore, when detecting a failure, the temperature control such as PID control is performed to control the temperature of the humidity sensitive film. It is not necessary to keep the temperature of 22 constant.

The determination device 5 of the embodiment includes an abnormality determination unit 46, a humidity determination unit 47, a condition determination unit 48, and an integration number determination unit 49.
As a result, even a state in which dew condensation water adheres to the moisture-sensitive film 22 is not determined as a failure.
More specifically, when dew condensation water adheres to the moisture-sensitive film 22, the original relative humidity and the post-relative humidity do not change before and after heating (see FIG. 9B). Until such a case, the condition determination unit 48 confirms whether or not the condition is such that the condensed water adheres so as not to determine the failure. Then, if it is determined that the condition is such that the condensed water does not adhere, and the failure determination is repeated by the integration number determination unit 49, it is determined that the failure occurs.

According to the determination device 5 of the embodiment, the failure determination unit 45 does not determine the failure when the temperature of the intake air is 10 degrees or less.
When the temperature of the intake air is low, the range of values that can be taken as absolute humidity is smaller than when the temperature of the intake air is high. Therefore, the failure is judged using only the absolute humidity value in this narrow range. You will have to.

Therefore, by setting the temperature of the intake air to a temperature higher than a predetermined value, a wider range of absolute humidity values can be used for determining the failure. As a result, the failure can be determined using the absolute humidity value in a wider range, so that the accuracy of the failure determination can be improved and the erroneous determination can be suppressed.

According to the determination device 5 of the embodiment, the humidity sensor 3 has a terminal for outputting the relative humidity and a flow rate detecting unit for outputting the flow rate of the intake air, and the flow rate is output via the terminal for outputting the relative humidity. Has been done.
As a result, the terminals of the humidity detection unit 37 and the flow rate detection unit can be shared, and the number of terminals can be reduced.

The determination device 5 of the embodiment outputs a signal for operating the notification unit 50 when the failure determination unit 45 determines that the failure has occurred. As a result, it is possible to notify the occupant of the vehicle of the failure and prevent the humidity detection unit 37 from continuing to operate the internal combustion engine 2 with the failure.

[Modification example]
Various modifications of the present invention can be considered without departing from the gist thereof.
In the embodiment, the humidity sensor chip 21 has the heating unit 40, but the heating unit 40 may be provided outside the humidity sensor chip 21.

In the examples, the reference values of the original relative humidity and the posterior relative humidity in the humidity determination unit 47 are both 90% or more, but this value is not limited and other values may be used.
In the embodiment, the predetermined conditions in the condition determination unit 48 are that the temperature of the intake air is 30 degrees or higher and the temperature of the hydraulic oil of the internal combustion engine 2 is 80 degrees or higher, but the temperature of the intake air and The temperature of the hydraulic oil of the internal combustion engine 2 is not limited to these values, and may be other values.

In the embodiment, the total number of times determination unit 49 determines whether or not it exceeds 5, but the value is not limited to this value and may be another value.
Further, in the embodiment, the temperature of the intake air in which the failure determination unit 45 does not determine the failure is 10 degrees or less, but the temperature of the intake air is not limited to this value and may be another value. Good.

Further, in the examples, the case where the post-temperature becomes higher than the original temperature by heating the heating unit 40 is shown, but the post-temperature may be lower than the original temperature. More specifically, the post-temperature can be made lower than the original temperature by stopping the heating of the heating unit 40 from the state in which the moisture-sensitive film 22 is preheated by the heating unit 40. Further, the post-temperature can be made lower than the original temperature by suppressing the output of the heating unit 40 from the state in which the moisture-sensitive film 22 is preheated by the heating unit 40.

Even when the post-temperature is lower than the original temperature, the failure determination unit 45 compares the estimated value of the relative humidity at the post-temperature with the actual post-relative humidity, and for example, the difference between the two values is predetermined. If it is farther than the value, it can be determined that the humidity detection unit 37 has failed.

The original temperature and the post-temperature may be the temperatures in the constant temperature state before and after the temperature drop as shown in FIG. 12 (a), and may be the temperature during the temperature drop as shown in FIG. 12 (b). Good.
The black circles in the figure indicate the time when the original temperature and the post temperature are detected.

1 Humidity measurement device 2 Internal combustion engine 5 Judgment device 37 Humidity detection unit 39 Temperature detection unit 40 Heating unit 44 Temperature rise command unit 45 Failure judgment unit

Claims (15)

It has a humidity sensitive film (22) existing in the intake passage (6) through which the intake air sucked into the internal combustion engine (2) for a vehicle flows, and outputs the relative humidity of the intake air from the capacitance of the moisture sensitive film. Humidity detection unit (37)
A temperature detection unit (39) that detects the temperature of the moisture-sensitive film and outputs this temperature,
In the determination device (5) for determining the failure of the humidity sensor (3) including the heating unit (40) for heating the moisture-sensitive film.
The heating portion is arranged on the back surface side of the moisture-sensitive film.
The temperature of the moisture-sensitive film rises when it is heated by the heating unit, and the temperature of the moisture-sensitive film rises.
The temperature detected at a predetermined time is the original temperature, the relative humidity at the original temperature is the original relative humidity, and the temperature different from the original temperature detected after heating by the heating unit or after the heating is stopped by the heating unit. Is referred to as post-temperature, and the relative humidity at the post-temperature is referred to as post-relative humidity.
A failure determination unit (45) for determining a failure of the humidity detection unit by comparing the estimated value of the relative humidity at the post-temperature estimated from the original relative humidity and the post-temperature with the post-relative humidity. Prepare ,
An abnormality determination unit (46) for determining whether or not the detected value is abnormal by comparing the estimated value of the relative humidity at the post-temperature with the post-relative humidity.
A humidity determination unit (47) that determines whether or not both the original relative humidity and the rear relative humidity are equal to or higher than a predetermined relative humidity when the abnormality determination unit determines that the abnormality is present.
The humidity determination unit has a condition determination unit (48) for determining whether or not a predetermined condition is satisfied when it is determined that both the original relative humidity and the rear relative humidity are equal to or higher than the predetermined relative humidity.
Wherein the predetermined condition, the determination device that the temperature of the intake air, characterized in der Rukoto predetermined temperature or more. In the determination device according to claim 1,
Wherein the predetermined condition, the temperature of the intake air is higher than a predetermined temperature, and the determination device that the temperature of the hydraulic oil of the internal combustion engine, characterized in der Rukoto predetermined temperature or more. It has a humidity sensitive film (22) existing in the intake passage (6) through which the intake air sucked into the internal combustion engine (2) for a vehicle flows, and outputs the relative humidity of the intake air from the capacitance of the moisture sensitive film. Humidity detection unit (37)
A temperature detection unit (39) that detects the temperature of the moisture-sensitive film and outputs this temperature,
In the determination device (5) for determining the failure of the humidity sensor (3) including the heating unit (40) for heating the moisture-sensitive film.
The temperature of the moisture-sensitive film rises when it is heated by the heating unit, and the temperature of the moisture-sensitive film rises.
The temperature detected at a predetermined time is the original temperature, the relative humidity at the original temperature is the original relative humidity, and the temperature different from the original temperature detected after heating by the heating unit or after the heating is stopped by the heating unit. Is referred to as post-temperature, and the relative humidity at the post-temperature is referred to as post-relative humidity.
A failure determination unit (45) for determining a failure of the humidity detection unit by comparing the estimated value of the relative humidity at the post-temperature estimated from the original relative humidity and the post-temperature with the post-relative humidity. Prepare,
An abnormality determination unit (46) for determining whether or not the detected value is abnormal by comparing the estimated value of the relative humidity at the post-temperature with the post-relative humidity.
A humidity determination unit (47) that determines whether or not both the original relative humidity and the rear relative humidity are equal to or higher than a predetermined relative humidity when the abnormality determination unit determines that the abnormality is present.
When the humidity determination unit determines that both the original relative humidity and the rear relative humidity are equal to or higher than the predetermined relative humidity, the condition determination unit (48) determines whether or not the predetermined condition is satisfied.
When the condition determination unit determines that the predetermined condition is satisfied, it has an integration number determination unit (49) that increases the integration number by 1 and determines whether or not the integration number exceeds the predetermined number.
It said failure determining unit determining device the number of integrations is characterized that you determined that failure of the humidity sensor when it is determined to exceed the predetermined number of times by the accumulation number determination unit. In the determination device according to claim 3,
The predetermined condition is a determination device, characterized in that the temperature of the intake air is equal to or higher than the predetermined temperature, and the temperature of the hydraulic oil of the internal combustion engine is equal to or higher than the predetermined temperature. In the determination device according to any one of claims 1 to 4.
Wherein after the temperature is determined and wherein the der Rukoto those detected after a temperature rise of the moisture sensitive film. In the determination device according to any one of claims 1 to 4.
Wherein after the temperature is determined and wherein the der Rukoto those detected after temperature drop of the moisture sensitive film. In the determination device according to any one of claims 1 to 6,
A determination device characterized in that a failure determination by the failure determination unit is performed when other devices are not controlled based on the relative humidity. In the determination device according to claim 7,
The determination device, characterized in that the failure determination by the failure determination unit is performed at the start of energization of the humidity detection unit. In the determination device according to claim 7,
A determination device characterized in that the failure determination by the failure determination unit is performed when the vehicle is decelerating. In the determination device according to claim 7,
The failure determination of the failure by the determination unit, determining unit, wherein Rukoto done when the vehicle is stopped. In the determination device according to any one of claims 1 to 10.
After determination of the failure by the failure determination section, wherein the temperature is the original temperature, or, after the relative humidity has become the source relative humidity, the Rukoto control of other devices is performed based on the relative humidity A characteristic judgment device. In the determination device according to any one of claims 1 to 11.
The humidity sensor has a humidity sensor chip (21) having the humidity detection unit, and has a humidity sensor chip (21).
The humidity sensor chip is a determination device having the heating unit. The determination device according to any one of claims 1 to 12.
A determination device, characterized in that the failure determination by the failure determination unit is not performed when the temperature of the intake air is equal to or lower than a predetermined temperature. In the determination device according to any one of claims 1 to 13.
The humidity sensor has a terminal for outputting the relative humidity and a flow rate detecting unit for outputting the flow rate of the intake air.
The flow is characterized that you have been outputted through the terminal determining unit. In the determination device according to any one of claims 1 to 14.
A determination device characterized in that when the failure determination unit determines a failure, a signal for operating the notification unit (50) is output.

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