JP2017201293A - Determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidity detector with which it is possible to detect a fault in a humidity detection unit having a moisture sensitive film present in an intake passage.SOLUTION: A determination device of the present invention includes a fault determination unit for comparing the estimated value of relative humidity at a post temperature estimated from a source relative humidity and a post temperature to a post relative humidity and thereby determining a fault in a humidity detection unit. Here, a temperature detected at a prescribed time is defined as the source temperature, a relative humidity at the source temperature is defined as a source relative humidity, a temperature different from the source temperature that is detected after heating by a heating unit or after heating by the heating unit is stopped is defined as the post temperature, and a relative humidity at the post temperature is defined as the post relative humidity. Thus, when the estimated value of relative humidity at the post temperature and the post relative humidity are compared and values of the two are more separate than a prescribed value, it can be determined that the humidity detection unit is faulty. Therefore, a determination device can be provided with which it is possible to detect a fault in a humidity detection unit having a moisture sensitive film present in an intake passage.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a determination device that determines a failure of a humidity sensor that measures the humidity of intake air taken into a vehicle internal combustion engine.

In recent years, there is an increasing demand for measuring the humidity of intake air for the purpose of improving the fuel consumption of an internal combustion engine and cleaning exhaust gas.
As a humidity sensor for measuring the humidity of the intake air, one having the following configuration is known.
The humidity sensor has a humidity sensitive film that exists in the intake passage through which the intake air drawn into the vehicle internal combustion engine flows, and outputs a relative humidity of the intake air from the capacitance of the moisture sensitive film, A temperature detection unit that detects the temperature of the wet film and outputs the temperature, and a heating unit that heats the moisture sensitive film are provided. And humidity detection accuracy is maintained by always heating a moisture sensitive film in a heating part, and suppressing dew condensation and pollution of a moisture sensitive film (for example, refer to patent documents 1).

Here, as a factor for deteriorating the humidity detection accuracy, not only dew condensation or contamination of the moisture 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.

  In addition, since the humidity sensor of patent document 1 is the structure which continues heating a humidity detection part and a temperature detection part with a heating part, the temperature of a temperature detection part will rise and the detection accuracy of the temperature of intake air will deteriorate. End up. Further, as the temperature of the humidity detection unit increases, the temperature of the moisture sensitive film also increases, leading to a decrease in absolute humidity detection accuracy (see FIG. 10). Furthermore, since the heating unit is continuously heated, power consumption is also increased.

JP-A-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 moisture sensitive film present in an intake passage.

  The determination apparatus of the present invention has a humidity sensing film that exists in an intake passage through which intake air drawn into an internal combustion engine for a vehicle flows, and outputs humidity detection that outputs the relative humidity of the intake air from the capacitance of the moisture sensing film And detecting a temperature of the moisture-sensitive film, and determining a failure of a humidity sensor including a temperature detection unit that outputs the temperature and a heating unit that heats the moisture-sensitive film.

In addition, the temperature of the moisture sensitive film is increased by being heated by the heating unit.
Here, the temperature detected at a predetermined time is the original temperature, the relative humidity at the original temperature is the original relative humidity, the temperature that is different from the original temperature detected after heating by the heating unit or after the heating unit stops heating is the post temperature. The relative humidity at the post temperature is referred to as post relative humidity.

  And the failure determination part which determines the failure of a humidity detection part by comparing the estimated value of the relative humidity in the back temperature estimated from the original relative humidity and the back temperature with the back relative humidity is provided.

Thereby, the estimated value of the relative humidity at the post-temperature is compared with the actual post-relative humidity. For example, when the difference between the two values is larger than a predetermined value, it can be determined that the humidity detection unit is malfunctioning. .
For this reason, it is possible to detect a failure of the humidity detector having the moisture sensitive film present in the intake passage.
Note that the temperature output from the temperature detection unit includes an electrical signal such as a voltage value that can be converted into a temperature.
Similarly, the relative humidity output from the humidity detector includes an electrical signal such as a voltage value that can be converted into relative humidity.

1 is an intake / exhaust system of an internal combustion engine for a vehicle (Example). (A) Humidity sensor and flow rate sensor viewed from intake air flow upstream side, (b) Cross section of flow rate sensor along the flow direction of intake air (Example). It is explanatory drawing of a moisture sensitive film | membrane (Example). It is a perspective view of a humidity sensor (example). It is sectional drawing of the humidity sensor which follows the VV line | wire in FIG. 4 (Example). It is a flowchart showing the control method of a determination apparatus (Example). It is explanatory drawing of the method of calculating | requiring the estimated value of the relative humidity in the post temperature using a humid air diagram (Example). (A) It is explanatory drawing of the change of the relative humidity before and behind heating at the time of normal, (b) It is explanatory drawing of the change of the relative humidity before and after heating at the time of abnormality (Example). (A) It is explanatory drawing of the change of the relative humidity before and behind heating at the time of normal, (b) It is explanatory drawing of the change of the relative humidity before and after the heating at the time of dew condensation (Example). It is explanatory drawing of the precision of the temperature of a moisture-sensitive film using a humid air diagram, and absolute humidity (Example). It is explanatory drawing of a source temperature and a back temperature (Example). It is explanatory drawing of a source temperature and a back temperature (modification example).

  Hereinafter, modes for carrying out the invention will be described using examples. In addition, an Example discloses a specific example, and it cannot be overemphasized that this invention is not limited to an Example.

[Configuration of Example]
First, an intake / exhaust system of a vehicle internal combustion engine 2 in which a humidity measuring device 1 is incorporated will be described with reference to FIG. Here, the humidity measuring device 1 includes a humidity sensor 3 and a determination device 5 described later.

The internal combustion engine 2 includes an intake passage 6 that guides intake air to the cylinder and an exhaust passage 7 that exhausts exhaust gas generated in the cylinder to the atmosphere.
The intake passage 6 is constituted by internal passages of an intake pipe, an intake manifold, and an intake port.
The intake pipe is a passage member from the outside air intake port to the intake manifold. The intake pipe includes an air cleaner 8 that removes dust and dirt contained in the intake air, a humidity sensor 3 that measures the humidity of the intake air, A flow rate sensor 9 for measuring the flow rate of the intake air, a throttle valve 10 for adjusting the intake air amount sucked into the cylinder, and the like are provided.
An intake pressure sensor 11 that measures the pressure of intake air is disposed downstream of the throttle valve 10 in 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 constituted by internal passages of an exhaust port, an exhaust manifold, and 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 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.
An air-fuel ratio sensor 12 that measures the concentration of oxygen in the exhaust gas is disposed in the exhaust path 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. The ECU 13 also includes 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, and data and programs necessary for control of the internal combustion engine 2. Various memories for storing and holding, an output circuit for outputting signals necessary for controlling the internal combustion engine 2 based on the processing results of the CPU, and the like are provided.

In addition to the humidity sensor 3, the flow sensor 9, the intake pressure sensor 11, and the air-fuel ratio sensor 12, various sensors that output signals to the ECU 13 include an oil temperature sensor 14 that detects the temperature of the working oil of the internal combustion engine 2, A rotation speed sensor 15 for detecting the rotation speed of the internal combustion engine 2 and the like are included.
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 that injects 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 it.
Moreover, ECU13 has the determination apparatus 5 explained in full detail behind.

With reference to FIG. 2, the humidity sensor 3 and the flow rate sensor 9 of an Example are demonstrated in detail.
The flow sensor 9 is disposed in the intake passage 6.
Hereinafter, the direction in which the intake air flows in the intake passage 6 may be referred to as a direction F.

The flow sensor 9 holds the flow sensor chip 17 and protrudes to the inner periphery of the intake passage 6 to detect the flow rate of the intake air.
The flow sensor 9 is provided with a resin material and has a passage formed therein.
As for the structure of the passage formed inside the flow sensor 9, for example, a bypass passage 18 and a sub-bypass passage 19 are provided.

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. An intake port 18 a is provided on the upstream side of the bypass passage 18, and a discharge port 18 b is provided on the downstream side of the bypass passage 18.
A discharge port restrictor 18 c that restricts the flow of intake air passing through the bypass passage 18 is formed on the downstream side of the bypass passage 18.

  The sub-bypass passage 19 includes an inlet 19a through which a part of the intake air flowing through the bypass passage 18 throttled by the outlet throttle 18c flows, and an outlet 19b that returns the intake air that has passed through the sub-bypass passage 19 to the intake passage 6. Prepare. Then, the intake air flowing in from the inlet 19a is U-turned inside the flow rate sensor 9 and led to the outlet 19b.

The flow rate sensor chip 17 includes a flow rate detection unit that outputs a flow rate, and the flow rate detection unit includes 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 the heat transfer of the intake air passing through the inside of the sub-bypass passage 19, and has a well-known configuration having a heating resistor and a resistance temperature detector on the surface. It has become.
The flow rate output from the flow rate detection unit includes an electrical 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 periphery of the intake passage 6 to detect the humidity of the intake air.
The humidity sensor 3 protrudes so that the longitudinal direction is orthogonal to the direction F when the protruding direction is the longitudinal direction.
The humidity sensor chip 21 has, for example, a moisture sensitive film 22 that is sensitive to the humidity of the intake air. Here, the humidity sensor chip 21 has a moisture sensitive film 22 on its surface, and is held by the humidity sensor 3 so that the moisture 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 moisture sensitive film 22 changes according to the humidity, and outputs the relative humidity. And the moisture sensitive film | membrane 22 is a polymer film, and an own electrostatic capacitance changes by the quantity of the water molecule taken in according to ambient humidity changing.
More specifically, as shown in FIG. 3, the sensor chip 21 has a capacitance value detected between the electrodes by allowing water molecules to enter the moisture sensitive film 22 in an amount corresponding to the ambient humidity. It has a changing structure. In addition, the dotted line in a figure represents the electric force line.

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

Further, in the intake passage 6, a mounting hole penetrating the inside and outside of the intake passage 6 is formed at a location where the humidity sensor 3 and the flow rate sensor 9 are mounted. Then, the humidity sensor 3 and the flow rate sensor 9 are fixed to the intake passage 6 by the base 23 being fitted into the mounting hole and fixed to the intake passage 6.
Further, the base 23 is provided with a connector 25, and signals of flow rate and relative humidity are output from 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 includes a humidity sensor chip 21, an FPC circuit board 33 on which the humidity sensor chip 21 is mounted, and a lead frame 34a connected to terminals of the circuit board 33 by wire bonding. To 34d, and the whole is molded by the resin member 35.
Here, the lead frame 34b has a mounting portion 36 for mounting the circuit board 33 at the end thereof. The end portions of the lead frames 34 a to 34 d that are 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 moisture 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 path 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 that are different from the mounting portion 36 are electrically connected to the terminals in the connector 25, respectively. The lead frames 34 a to 34 d excluding the mounting portion 36 are embedded in the base portion 23.
Here, the lead frame 34a is connected to a DC power source, and the lead frame 34b is grounded. The lead frames 34c and 34d exchange data signals with the ECU 13 in accordance with, for example, the I2C protocol.

Here, the humidity sensor chip 21 includes a humidity detection unit 37, a temperature detection unit 39, and a heating unit 40, as shown in FIG.
The humidity detection unit 37 includes a moisture sensitive film 22 and a relative humidity output unit 41 that detects the relative humidity from the capacitance of the moisture sensitive film 22 and outputs a voltage signal corresponding to the relative humidity.
The temperature detection unit 39 includes a temperature measurement unit 42 that detects the temperature of the moisture sensitive film 22, and a temperature output unit 43 that detects the temperature from a signal from the temperature measurement unit 42 and outputs a voltage signal corresponding to the temperature.
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, and outputs a signal such as relative humidity in accordance with a command signal from the ECU 13 via the lead frames 34c and 34d. The moisture sensitive film 22 is heated.

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

The source temperature and the post temperature may be temperatures in a constant temperature state before and after the temperature rise as shown in FIG. 11 (a), or may be a temperature during the temperature rise as shown in FIG. 11 (b). Good.
In addition, the black circle in the figure represents the detection time of the original temperature and the subsequent temperature.

The failure determination by the failure determination unit 45 is performed when other devices are not controlled based on the relative humidity.
In addition, after the failure is determined by the failure determination unit 45, after the temperature becomes the original temperature, the other devices are controlled based on the relative humidity.

Moreover, the determination apparatus 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 rear temperature with the rear relative humidity.
The humidity determination unit 47 determines whether both the original relative humidity and the rear relative humidity are 90% or more when the abnormality determination unit 46 determines that there is an abnormality.
The condition determination unit 48 determines whether or not a 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 ° C. or more and the temperature of the working oil of the internal combustion engine 2 is 80 ° C. or more.
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 the integration number exceeds 5.

The failure determination by the failure determination unit 45 is not performed when the temperature of the intake air is 10 degrees or less.
Furthermore, the determination device 5 outputs a signal for operating the notification unit 50 when it is determined that there is a failure (see FIG. 1).

[Control method of embodiment]
A specific example of the control method of the determination apparatus 5 of the embodiment will be described with reference to the flowchart of FIG.
First, in step S100, it is determined whether the temperature of the intake air is higher than 10 degrees.
When 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 from the temperature detection unit 39.

Next, in step S110, it is determined whether or not the relative humidity is used for controlling other devices. Here, the other devices are, for example, the throttle valve 10 and the fuel injection valve 16.
When it is determined that the relative humidity is used for controlling other devices (YES), the process is terminated.
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 the control of other devices is, for example, the start of energization of the humidity detector 37, the deceleration of the vehicle, and the stop of the vehicle.
Note that when the energization of the humidity detection unit 37 is started, 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 the control of other devices. Further, since the fuel supply to the internal combustion engine 2 is interrupted when the vehicle is decelerated, the control of the internal combustion engine 2 or the like is not performed 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 as the original relative humidity and the original temperature. The process proceeds to step S130.

Next, in step S <b> 130, the temperature of the moisture sensitive film 22 is raised by the heating unit 40.
Note that the temperature of the moisture sensitive film 22 is raised by the heating unit 40 not only when the moisture sensitive film 22 is changed from being heated by the heating part 40 to being heated, but also by the moisture sensitive film. This includes a case where the state 22 is shifted from a state heated in advance by the heating unit 40 to a state where it is further heated.
Step S <b> 130 corresponds to the function of the temperature increase 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 rear relative humidity and the rear temperature. The process proceeds to step S150.

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

More specifically, the absolute humidity amount can be calculated first from the original relative humidity by using the wet air diagram shown in FIG. 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 moisture sensitive film 22 is heated, the value of the relative humidity at the post-temperature can be estimated from the wet air diagram. For example, the estimated value of the relative humidity when the rear temperature is 35 degrees and the absolute humidity is 10 g / kg is 28.3%. Then, it is determined whether or not the detected value of the humidity detector 37 is abnormal based on whether or not the estimated value of the relative humidity at the rear temperature substantially matches the rear relative humidity (see FIG. 8). In addition, the arrow in a figure represents the change of the relative humidity corresponding to the temperature change of Fig.8 (a).
The wet air diagram is stored in advance in the memory of the ECU 13 as a data set or a calculation formula.

When 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 heating of the moisture sensitive film 22 by the heating unit 40 is stopped. Then, the process proceeds to step S240 and waits until the temperature of the moisture sensitive film 22 detected by the temperature detection unit 39 becomes the original temperature, and then the process is terminated.
Note that after the processing is completed, it is possible to control other devices based on the relative humidity.
FIG. 8A and FIG. 8B show temporal changes in the original temperature, the original relative humidity, the subsequent temperature, and the rear relative humidity before and after the temperature increase of the moisture sensitive film 22, respectively.

Next, in step S160, it is determined whether the original relative humidity and the rear relative humidity are 90% or more.
When it is determined that the original relative humidity and the rear relative humidity are 90% or more (YES) (see FIG. 9B), the process proceeds to step S170.
When it is determined that the rear 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.
FIG. 9A and FIG. 9B show temporal changes in the original temperature, the original relative humidity, the subsequent temperature, and the rear relative humidity before and after the temperature increase of the moisture sensitive film 22, respectively.

Next, in step S170, it is determined whether 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 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 satisfies the conditions of 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 moisture sensitive film by the heating unit 40 The temperature rise of 22 is stopped. Then, the process proceeds to step S240 and waits until the temperature of the moisture sensitive film 22 detected by the temperature detection unit 39 becomes the original temperature, and then the process is terminated.
Step S <b> 170 corresponds to the function of the condition determination unit 48.

Next, in step S180, the number of integration is increased by 1, and the process proceeds to step S190.
Next, in step S190, it is determined whether the number of integrations exceeds 5.
If it is determined that the number of integration exceeds 5 (YES), the process proceeds to step S200, it is determined that there is a failure, the process proceeds to step S210, the heating of the moisture sensitive film 22 by the heating unit 40 is stopped, and then the process proceeds to step S220. To do. In step S220, a signal for operating the notification unit 50 is output. Step 150 and step S200 correspond to the function of the failure determination unit 45.
When it determines with the frequency | count of integration being 5 or less (NO), it transfers to step S230 and stops the temperature rising of the moisture sensitive film 22 by the heating part 40. Then, the process proceeds to step S240 and waits until the temperature of the moisture sensitive film 22 detected by the temperature detection unit 39 becomes the original temperature, and then the process is terminated.
Note that steps S180 and S190 correspond to the function of the integration number determination unit 49.

[Effect of Example]
The determination device 5 according to the embodiment includes 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 subsequent temperature estimated from the original relative humidity and the subsequent temperature with the subsequent relative humidity. 45.

Thereby, the estimated value of the relative humidity at the rear temperature is compared with the actual rear relative humidity. For example, when the difference between the two values is larger than a predetermined value, it is determined that the humidity detection unit 37 is malfunctioning. it can.
For this reason, it is possible to detect a failure of the humidity detector 37 having the moisture sensitive film 22 present in the intake passage 6.

According to the determination device 5 of the embodiment, the failure determination by the failure determination unit 45 is performed when other devices are not controlled based on the relative humidity.
Thereby, since the heating part 40 of the moisture sensitive film | membrane 22 is not performed at the time of control of another apparatus, the temperature of the moisture sensitive film | membrane 22 does not rise. For this reason, the accuracy of the absolute humidity calculated from the wet air diagram can be ensured.

Here, the reason why the accuracy of the absolute humidity is deteriorated when the absolute humidity is obtained from the relative humidity using the humid air diagram as the temperature of the moisture sensitive film 22 is higher will be described with reference to FIG.
For example, the variation range of the absolute humidity corresponding to the variation range of 3% above and below the relative humidity of 70% when the temperature of the moisture sensitive film 22 is 30 degrees is 18.3 to 19.7 g / kg. The absolute humidity when the temperature is 30 degrees and the relative humidity is 70% is 18.8 g / kg.
On the other hand, the fluctuation range of the absolute humidity corresponding to the fluctuation range of 3% above and below the relative humidity at the absolute humidity of 18.8 g / kg at the temperature of the humidity sensitive film 22 is 16.4 to 21.3 g / kg. It has become.

That is, the higher the temperature of the moisture sensitive film 22, the greater the deviation amount of the absolute humidity with respect to the deviation of 1% relative humidity.
For this reason, the accuracy of the absolute humidity which can be calculated | required from a humid air diagram becomes so that the temperature of the moisture sensitive film | membrane 22 is low.
Note that heating of the moisture sensitive film 22 by the heating unit 40 is only at the time of determination of failure, and since it is not always heating, power consumption can be reduced.

According to the determination device 5 of the embodiment, after the failure determination by the failure determination unit 45, after the temperature becomes the original temperature, the other devices are controlled based on the relative humidity.
Thereby, after the temperature of the moisture sensitive film | membrane 22 returns to original temperature, since control of another apparatus is performed, the precision of the absolute humidity calculated from a humid air diagram can be ensured more.
Further, after the relative humidity returns to the original relative humidity, the other devices may be controlled. 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 secured more.

According to the determination device 5 of the embodiment, the humidity sensor 3 includes the humidity sensor chip 21 including the humidity detection unit 37 and also includes the heating unit 40.
Thereby, it is not necessary to provide the heating unit 40 separately from the humidity sensor chip 21.
The humidity sensor chip 21 has a temperature detection unit 39.
Thereby, since the temperature measurement part 42 can be provided in the vicinity of the moisture sensitive film | membrane 22, the temperature of the moisture sensitive film | membrane 22 can be detected more correctly.
In addition, since the temperature measuring unit 42 and the moisture sensitive film 22 are close to each other and the time delay of the temperature rise detection due to heating can be suppressed, temperature control such as PID control is particularly performed at the time of failure detection. There is no need to keep the temperature of 22 constant.

The determination device 5 according to 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.
Thereby, even the state where condensed water has adhered to the moisture sensitive film 22 is not determined as a failure.
More specifically, when condensed water adheres on the moisture sensitive film 22, the original relative humidity and the rear 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 that the condensed water adheres so as not to determine that there is a failure. Then, if it is determined that the condensed water does not adhere, and the failure determination is repeated by the integration number determination unit 49, it is determined as a failure.

According to the determination device 5 of the embodiment, the failure determination by the failure determination unit 45 is not performed 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 the absolute humidity is smaller than when the temperature of the intake air is high. Therefore, the failure determination is made using only the absolute humidity value within this narrow range. Will have to.

  Thus, 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 failure determination. As a result, failure determination can be performed using a wider range of absolute humidity values, so the accuracy of failure determination can be increased and erroneous determination can be suppressed.

According to the determination apparatus 5 of the embodiment, the humidity sensor 3 has a terminal that outputs relative humidity and a flow rate detection unit that outputs the flow rate of intake air, and the flow rate is output via the terminal that outputs relative humidity. Has been.
Thereby, 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 according to the embodiment outputs a signal for operating the notification unit 50 when the failure determination unit 45 determines that a failure has occurred. Thereby, it is possible to notify the vehicle occupant of the failure and prevent the internal combustion engine 2 from being continuously operated while the humidity detection unit 37 is broken.

[Modification]
Various modifications can be considered for the present invention 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 embodiment, the reference values of the original relative humidity and the rear relative humidity in the humidity determination unit 47 are both 90% or more, but are not limited to this value, and may be other values.
In the embodiment, the predetermined condition in the condition determination unit 48 is a condition in which the temperature of the intake air is 30 degrees or more and the temperature of the hydraulic oil of the internal combustion engine 2 is 80 degrees or more. The temperature of the hydraulic oil of the internal combustion engine 2 is not limited to these values, but may be other values.

In the embodiment, the integration number determination unit 49 performs the determination based on whether or not the number exceeds 5. However, the value is not limited to this value, and may be another value.
Further, in the embodiment, the temperature of the intake air at which failure determination by the failure determination unit 45 is not performed is 10 degrees or less. However, the temperature of the intake air is not limited to this value, and may be other values. Good.

  Moreover, in the Example, although the case where after temperature became higher than original temperature by the heating of the heating part 40 was shown, it is good also as a structure where after temperature becomes lower than 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. Moreover, the post temperature can be lowered from the original temperature by suppressing the output from the heating unit 40 from the state in which the moisture sensitive film 22 is preheated by the heating unit 40.

  Even when the rear temperature is lower than the original temperature, the failure determination unit 45 compares the estimated value of the relative humidity at the rear temperature with the actual rear relative humidity. For example, the difference between the two values is a predetermined value. When the distance is larger than the value, it can be determined that the humidity detection unit 37 is malfunctioning.

The source temperature and the post temperature may be temperatures in a constant temperature state before and after the temperature decrease as shown in FIG. 12 (a), or may be a temperature during the temperature decrease as shown in FIG. 12 (b). Good.
In addition, the black circle in the figure represents the detection time of the original temperature and the subsequent temperature.

DESCRIPTION OF SYMBOLS 1 Humidity measuring device 2 Internal combustion engine 5 Judgment device 37 Humidity detection part 39 Temperature detection part 40 Heating part 44 Temperature rise command part 45 Failure judgment part

Claims (16)

There is a moisture sensitive film (22) present in the intake passage (6) through which the intake air drawn into the vehicle internal combustion engine (2) flows, and the relative humidity of the intake air is output from the capacitance of the moisture sensitive film A humidity detector (37) to perform,
A temperature detector (39) for detecting the temperature of the moisture sensitive film and outputting the temperature;
In a determination device (5) for determining a failure of a humidity sensor (3) including a heating unit (40) for heating the moisture sensitive film,
The humidity-sensitive film is heated by the heating unit to increase the temperature,
The temperature detected at a predetermined time is an original temperature, the relative humidity at the original temperature is an original relative humidity, the temperature different from the original temperature detected after heating by the heating unit or after heating is stopped by the heating unit And the relative humidity at the post-temperature is referred to as post-relative humidity,
A failure determination unit (45) that determines a failure of the humidity detection unit 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. A determination apparatus comprising: The determination apparatus according to claim 1,
The determination apparatus according to claim 1, wherein the post temperature is detected after the temperature of the moisture sensitive film is increased. The determination apparatus according to claim 1,
The determination apparatus according to claim 1, wherein the post temperature is detected after the temperature of the moisture sensitive film is decreased. In the determination apparatus according to any one of claims 1 to 3,
The determination apparatus according to claim 1, wherein the determination of a failure by the failure determination unit is performed when other devices are not controlled based on the relative humidity. The determination apparatus according to claim 4,
The determination by the failure determination unit is performed at the start of energization of the humidity detection unit. The determination apparatus according to claim 4,
The determination by the failure determination unit is performed when the vehicle is decelerated. The determination apparatus according to claim 4,
The determination of a failure by the failure determination unit is performed when the vehicle is stopped. The determination apparatus according to any one of claims 1 to 7,
After the failure is determined by the failure determination unit, the temperature becomes the original temperature, or after the relative humidity becomes the original relative humidity, control of other devices is performed based on the relative humidity. Judgment device. In the determination apparatus according to any one of claims 1 to 8,
The humidity sensor has a humidity sensor chip (21) having the humidity detection unit,
The humidity sensor chip includes the heating unit. In the determination apparatus according to any one of claims 1 to 8,
The humidity sensor has a humidity sensor chip having the humidity detector.
The said humidity sensor chip does not have the said heating part, The determination apparatus characterized by the above-mentioned. In the determination apparatus as described in any one of Claim 9 or Claim 10,
The humidity sensor chip includes the temperature detection unit. In the determination apparatus as described in any one of Claims 1 thru | or 11,
An abnormality determination unit (46) for determining whether the detected value is abnormal by comparing the estimated value of the relative humidity at the post-temperature and the post-relative humidity;
A humidity determination unit (47) for determining 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 there is an abnormality;
A condition determination unit (48) for determining whether or not a predetermined condition is satisfied 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;
When this condition determination unit determines that the predetermined condition is satisfied, the integration number is increased by 1, and an integration number determination unit (49) that determines whether the integration number exceeds the predetermined number,
The failure determination unit determines that the humidity detection unit has failed when it is determined by the integration number determination unit that the integration number exceeds a predetermined number. The determination apparatus according to claim 12, wherein
The determination apparatus according to claim 1, wherein the predetermined condition is that the temperature of the intake air is equal to or higher than a predetermined temperature, and the temperature of hydraulic oil of the internal combustion engine is equal to or higher than a predetermined temperature. In the determination apparatus according to any one of claims 1 to 13,
The 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. The determination apparatus according to any one of claims 1 to 14,
The humidity sensor has a terminal that outputs the relative humidity, and a flow rate detection unit that outputs the flow rate of the intake air,
The determination apparatus, wherein the flow rate is output through the terminal. The determination apparatus according to any one of claims 1 to 15,
The determination apparatus characterized by outputting a signal for operating the notification unit (50) when the failure determination unit determines that there is a failure.

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