JP2021014987A - Humidity measuring device - Google Patents

Abstract

To provide a humidity measuring device capable of performing highly accurate humidity measurement with less noise due to the flow of air.SOLUTION: A humidity measuring device 1 of the present invention includes: a humidity detection element 4; a measurement chamber 5 in which the humidity detection element 4 is arranged; an introduction pipe 3 for introducing air toward the measurement chamber 5; and a partition 10 that separates the introduction pipe 3 and the measurement chamber 5 and has a communication passage that connects the introduction pipe 3 and the measurement chamber 5.SELECTED DRAWING: Figure 1B

Description

The present invention relates to a detection device suitable for measuring the humidity of intake air in an internal combustion engine.

In automobiles, an electronically controlled fuel injection system is adopted, and various sensors and control devices are arranged in the engine room. One of the sensors placed in the engine room is a humidity measuring device. This humidity measuring device is used for fuel control.

In internal combustion engines for automobiles, etc., in order to improve fuel efficiency, it is required to measure environmental conditions such as humidity in addition to the flow rate, temperature, and pressure of intake air with high accuracy. When measuring humidity in an engine, high responsiveness is required in addition to high detection accuracy.

As a background technique in this technical field, a humidity measuring device described in Japanese Patent Application Laid-Open No. 2015-232514 (Patent Document 1) is known. The humidity measuring device of Patent Document 1 is arranged in an intake passage through which intake air flows, and has a humidity sensor that generates a signal according to the humidity of the intake air flowing through the intake passage. The intake passage has a throttle that reduces the cross-sectional area of the flow path, and the humidity sensor is arranged in this throttle. The humidity measuring device of Patent Document 1 increases the flow velocity of the intake air by arranging the humidity sensor in the throttle, suppresses the retention of the intake air in the vicinity of the humidity sensor, and enhances the responsiveness of the humidity sensor. (See summary).

Further, Japanese Patent Application Laid-Open No. 2003-107033 (Patent Document 2) describes a gas sensor having a gas sensor element inserted and arranged in a housing. This gas sensor has a cylindrical outer cover and an inner cover having substantially the same central axis and having different diameters, which are fixed to the tip end side of the housing and have a side cover to be measured. The outer cover and the inner cover have an outer introduction hole and an inner introduction hole for introducing the gas to be measured from the outside of the outer cover to the inside of the inner cover, respectively (see summary).

JP-A-2015-232514 Japanese Unexamined Patent Publication No. 2003-107033

The humidity measuring device of Patent Document 1 can enhance the responsiveness. However, since the flow velocity of the intake air near the humidity sensor is increased, the air flow may affect the detection signal of the humidity sensor as noise. Therefore, in order to improve the accuracy of the humidity measuring device, there is a possibility that the noise generated by the air flow limits the accuracy.

The gas sensor of Patent Document 2 is specifically a sensor that detects an oxygen concentration, and the gas that has passed through the outer introduction hole and the inner introduction hole formed in the outer cover and the inner cover is the gas to be measured in which the gas sensor element is arranged. It is a structure that flows directly into the room. Therefore, when the humidity measuring device is configured with the structure of the gas sensor of Patent Document 2, the gas flowing into the gas chamber to be measured flows with a relatively large flow velocity in the vicinity of the gas sensor element. Therefore, the gas flow may affect the detection signal of the gas sensor element as noise, and the noise generated by the gas flow may limit the accuracy of the gas sensor.

An object of the present invention is to provide a humidity measuring device capable of performing highly accurate measurement with less noise due to air flow.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
In the humidity measuring device of the present invention, the introduction pipe that takes in the intake air into the physical quantity detection unit and the inlet portion of the introduction pipe have a first wall surface portion and a second wall surface portion located inside the first wall surface portion. The first wall surface portion and the second wall surface portion are provided so that the window of the first wall surface portion and the wall of the second wall surface portion overlap in a direction perpendicular to the introduction direction of the introduction pipe. The humidity measuring device is characterized in that the second wall surface portion has a shape in which walls and windows are alternately formed at predetermined intervals.

As a result, for example, even when measuring the humidity of the air flowing in the intake pipe in the intake system of an internal combustion engine, the noise to the humidity signal due to the air flow is reduced, and a high-speed response to the humidity change of the air flowing in the intake pipe can be obtained. , It can be realized regardless of the direction of air flow and the mounting direction of the humidity measuring device.

According to the present invention, it is possible to obtain a humidity measuring device capable of performing highly accurate humidity measurement with less noise due to the flow of air. Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments.

It is the schematic which shows the lower surface of the humidity measuring apparatus of one Example which concerns on this invention. It is the schematic which shows the AA cross section of FIG. 1A. It is the schematic which shows the cross section in the state which attached the humidity measuring apparatus of one Example which concerns on this invention to an intake pipe. It is a bottom view which shows the outline of the modified example which changed the structure of the introduction guide 2 about the humidity measuring apparatus of one Example which concerns on this invention.

Hereinafter, examples of the present invention will be described with reference to the drawings. Hereinafter, an example in which the humidity measuring device 1 according to the present invention is applied to the intake system of the internal combustion engine will be described, but the application target of the humidity measuring device 1 is not limited to the intake system of the internal combustion engine.

Further, the vertical direction in the following description is defined with reference to the vertical direction in FIG. 1B, and does not necessarily match the vertical direction in the state where the humidity measuring device is mounted.

FIG. 1A is a schematic view showing the lower surface of the humidity measuring device of the embodiment according to the present invention. FIG. 1B is a schematic view showing a cross section taken along the line AA of FIG. 1A.

As shown in FIGS. 1A and 1B, the humidity measuring device 1 of this embodiment includes a housing 1A, a humidity detecting element 4, a substrate 10, a measuring chamber 5, an introduction pipe 3, and air introduction portions 8a and 8b. The introduction guide 2 and the connection terminal 9 are provided.

The housing 1A is a resin member having a measurement unit accommodating space 13. The measurement unit accommodation space 13 accommodates a substrate 10 on which the humidity detection element 4 is mounted and a sensor cover 6 that covers the humidity detection element 4. A recess 6a is formed in the sensor cover 6, and the combination of the sensor cover 6 and the substrate 10 constitutes a measurement chamber 5 in which the humidity detection element 4 is housed in the recess 6a. That is, the humidity detection element 4 is arranged in the measurement chamber 5 composed of the sensor cover 6 and the substrate 10.

The housing 1A is fixed to the pipe wall 11 of the intake pipe (see FIG. 2), but the side fixed to the intake pipe wall 11 is called the proximal end side or the fixed side, and is from the proximal end side to the inside of the intake pipe 11. The side inserted into the formed air passage (air flow path) is called the tip side. The measurement unit accommodation space 13, the measurement chamber 5, the humidity detection element 4, the substrate 10, and the sensor cover 6 are configured at the end portion (base end portion) on the base end side of the housing 1A and are arranged outside the intake pipe 11. To.

In the housing 1A, the connector portion 9 is integrally formed of the resin forming the main body of the housing 1A. A plurality of connection terminals 9a project from the measurement unit accommodation space 13 in the inner space of the connector unit 9. That is, the connection terminal 9a is provided so as to project outward from the inner space (measurement unit accommodating space) 13 of the housing 1A. The connection terminal 9a is electrically connected to the humidity detection element 4 via the substrate 10 to enable power supply to the humidity detection element 4 and extraction of a detection signal from the humidity detection element 4. Hereinafter, the power supply and the detection signal will be referred to as electrical signals and will be described.

The housing 1A is formed with an introduction pipe (air introduction pipe) 3 extending from the measurement unit accommodating space 13 toward the end portion (tip portion) on the distal end side. A substrate 10 is provided at the end of the introduction pipe 3 on the base end side, and the substrate 10 closes most of the cross section of the air passage formed inside the introduction pipe 3. The substrate 10 is provided with air introduction portions (communication passages or communication holes) 8a and 8b, and the air passage of the introduction pipe 3 communicates with the measurement chamber 5 through the air introduction portions 8a and 8b. That is, the introduction pipe 3 and the air introduction units 8a and 8b form an introduction unit (air introduction unit) for introducing air into the measurement chamber 5.

In this embodiment, the housing 1A is composed of two members, a base end side housing member (first housing member) 1Aa and a tip end side housing member (second housing member) 1Ab. The base end side member 1Aa is provided with a measurement unit accommodating space 13, a measurement chamber 5, a humidity detection element 4, a substrate 10, a sensor cover 6, and a part of the base end side of the introduction pipe 3. The tip side member 1Ab is provided with a part of the tip side of the introduction pipe 3 and an introduction guide (air introduction guide) 2 formed at the tip of the introduction pipe 3.

The introduction guide 2 has a plurality of first introduction guide portions (first wall surface portions) 2a and a plurality of second introduction guide portions (second wall surface portions) that protrude toward the tip side from the inlet opening 3a of the introduction pipe 3 and guide the measurement medium. Part) 2b and. The plurality of second introduction guide portions 2b are arranged on the distal end side with respect to the inlet opening 3a of the introduction pipe 3 and on the radial outer side of the inlet opening 3a. The plurality of first introduction guide portions 2a are arranged on the tip side with respect to the inlet opening 3a of the introduction pipe 3 and on the radial outer side of the plurality of second introduction guide portions 2b. The plurality of first introduction guide portions 2a are arranged radially outside with respect to the plurality of second introduction guide portions 2b, and the plurality of second introduction guide portions 2b are radially inside with respect to the plurality of first introduction guide portions 2a. Is placed in.

Each of the plurality of second introduction guide portions 2b is arranged so as to be separated in the circumferential direction surrounding the inlet opening 3a, and a second circumferential gap (second window) is provided between two adjacent second introduction guide portions 2b. Part) 2d is formed. Each of the plurality of first introduction guide portions 2a is arranged so as to be spaced apart from each other in the circumferential direction surrounding the inlet opening 3a and the second introduction guide portion 2b, and is located between the two adjacent first introduction guide portions 2a. A circumferential gap (first window portion) 2c is formed. Further, the plurality of first introduction guide portions 2a and the plurality of second introduction guide portions 2b are arranged apart from each other in the radial direction, and are located between the plurality of first introduction guide portions 2a and the plurality of second introduction guide portions 2b. A radial gap 2e is formed in. As described above, the introduction guide 2 has a first introduction guide portion 2a, a second introduction guide portion 2b, a first window portion 2c, a second window portion 2d, and a radial gap 2e. As a result, the introduction guide 2 is configured with a passage (flow path) through which air flows from the outer peripheral side of the introduction guide 2 through the first window portion 2c and the second window portion 2d to the inner peripheral side of the introduction guide 2. ..

In this embodiment, the housing 1A is composed of two members, but it may be composed of one member or may be divided into three or more members. By configuring the housing 1A with two members, the portion composed of the base end side housing member 1Aa is standardized, and a plurality of models in which the configuration of the introduction guide 2 portion is changed are configured with a small number of parts. Can be done. Alternatively, it becomes easy to change the design of the part of the introduction guide 2.

Further, a plurality of first introduction guide portions 2a are formed on the front end side housing member 1Ab by forming a part of the introduction pipe 3 on the side opposite to the tip end side (measurement unit accommodation space 13 side) and the introduction guide 2. And a plurality of second introduction guide portions 2b can be integrally formed as a component.

Next, a mechanism for introducing the air flowing through the intake pipe 11 into the measurement chamber of the humidity measuring device 1 will be described.

FIG. 2 is a schematic view showing a cross section of the humidity measuring device according to the present invention in a state of being attached to an intake pipe.

The first window portion 2c and the second window portion 2d are arranged so as not to be aligned in a straight line in the radial direction. That is, the first introduction guide portion (first wall surface portion) 2a includes a first window portion 2c and a second introduction guide portion (second wall surface portion) 2b formed between two adjacent first introduction guide portions 2a. And are provided so as to overlap in the circumferential direction of the entrance opening 3a. Further, in the second introduction guide portion 2b, the second window portion 2d formed between the two adjacent second introduction guide portions 2b and the first introduction guide portion 2a overlap in the circumferential direction of the inlet opening 3a. It is provided as follows.

As a result, the introduction guide 2 prevents air from flowing straight from the outer peripheral side to the inner peripheral side. In this way, the first introduction guide portion 2a and the second introduction guide portion 2b of the introduction guide 2 form a labyrinth portion 7a in which the air passage is complicatedly bent.

In FIG. 2, Q1 and Q2 indicate the flow of air.

The air that has passed through the labyrinth portion 7a becomes a swirling flow and flows into the introduction pipe 3 from the inlet opening 3a. By swirling, the air flowing into the introduction pipe 3 flows so that the flow toward the substrate 10 side (base end side) and the flow from the substrate 10 side toward the inlet opening 3a side (tip side) coexist. Therefore, the portion of the introduction pipe 3 constitutes the gas exchange portion 7b. In the gas exchange unit 7b, the air is smoothly replaced, and the air in the vicinity of the substrate 10 is smoothly replaced.

In this embodiment, the air that has flowed into the introduction pipe 3 flows out from the inlet opening 3a to the outside of the introduction pipe 3. Therefore, the inlet opening 3a constitutes the outlet (exit opening) of the introduction pipe 3.

The introduction pipe 3 and the measurement chamber 5 are separated by a substrate 10, and the measurement chamber 5 has a diffusion portion 7c. That is, the air flow that flows through the introduction pipe 3 and reaches the substrate 10 is dammed by the substrate 10, and the air on the introduction pipe 3 side that reaches the vicinity of the substrate 10 is introduced into the measurement chamber 5 by diffusion through the air introduction portions 8a and 8b. To.

That is, the substrate 10 constitutes a damming portion (damping wall) for damming the air flow flowing through the introduction pipe 3. Alternatively, the substrate 10 constitutes a partition portion (partition wall) that separates the introduction pipe 3 and the measurement chamber 5. In order to block the air flow in the substrate 10, the air introduction portions (communication passages) 8a and 8b are formed on a part of the surface facing the inside of the introduction pipe 3.

For diffusion, air is introduced into the measurement chamber 5 by utilizing the phenomenon that the gas spreads in the space due to the difference in the concentration of the gas (the difference in the humidity of the air in this embodiment).

In the humidity measuring device 1 of this embodiment, gas exchange in the vicinity of the humidity detecting element 4 is performed by diffusion from the air introduction units 8a and 8b, and high-precision humidity measurement with less noise to the humidity signal due to the air flow is realized. ing.

In this embodiment, as the humidity detection element 4, a thermal type humidity detection element that detects humidity by measuring a change in heat conduction of the measurement medium based on the amount of heat released from the heating element exposed to the measurement medium is used as an example. As shown in, a capacitive humidity detection element may be used.

As described above, the introduction guide 2 is arranged on the upstream side of the introduction pipe 3 and is configured to positively exchange the air from the inlet opening 3a to the substrate 10 that separates the introduction pipe 3 and the measurement chamber 5. There is. In the introduction guide 2, the first introduction guide portion 2a, the second introduction guide portion 2b, the first window portion 2c, and the second window portion 2d are evenly distributed in the circumferential direction of the inlet opening 3a of the introduction pipe 3. Therefore, the inlet opening 3a of the introduction pipe 3 is opened inside the introduction guide 2 regardless of the direction perpendicular to the air introduction direction.

According to this configuration, the air that hits the introduction guide 2 is introduced into the introduction pipe 3 at the entire circumference (360 °) in the circumferential direction of the inlet opening 3a. Therefore, it is possible to introduce air into the humidity sensor element 4 regardless of the direction of the air flow, and it is possible to secure a high-speed response to a change in the humidity of the medium to be measured.

FIG. 3 is a bottom view showing an outline of a modified example in which the configuration of the introduction guide 2 is changed with respect to the humidity measuring device of one embodiment according to the present invention.

In this modified example, the introduction guide 2 has a blade-shaped portion 2f instead of the first introduction guide portion 2a and the second introduction guide portion 2b. Other configurations are the same as in the above-described embodiment.

A plurality of blade-shaped portions 2f are arranged at intervals in the circumferential direction on the radial outer side of the inlet opening 3a of the introduction pipe 3. A circumferential gap (window portion) 2g is formed between two adjacent blade-shaped portions 2f. The blade shape portion 2f has a curved shape on the plane of FIG. 3 (on the plane perpendicular to the air introduction direction of the introduction pipe 3), and constitutes a curved flow path 2g. The blade-shaped portion 2f, that is, the curved flow path 2g, imparts a turning force to the air flow flowing into the introduction pipe 3.

In particular, in this embodiment, air is introduced into the introduction pipe 3 from the entire circumference of the inlet opening 3a as in the above-described embodiment by evenly distributing the blade-shaped portions 2f over the entire circumference of the inlet opening 3a. be able to.

Also in this modified example, since the air can be introduced into the introduction pipe 3 while swirling, the same effect as that of the above-described embodiment can be obtained.

The first introduction guide portion 2a, the second introduction guide portion 2b, and the blade shape portion 2f are arranged radially outside the inlet opening 3a of the introduction pipe 3 from the tip portion (entrance opening 3a) of the introduction pipe 3. It is composed of a protruding portion formed so as to project to the side (tip side) opposite to the side (base end side) where the measurement chamber 5 is provided.

In recent years, automobile engine rooms are becoming more restricted in mounting layout due to an increase in mounting parts due to miniaturization and higher functionality. Therefore, it is desired that the humidity measuring device has few restrictions on the mounting direction and can be mounted in any direction. In this embodiment, since the inflow direction of air with respect to the introduction pipe 3 for introducing air into the measurement chamber 5 is not limited, the mounting direction of the humidity measuring device 1 is not limited. That is, the mounting direction of the humidity measuring device does not depend on the direction of the air flow. Therefore, the humidity measuring device of this embodiment has few restrictions on the mounting direction and is suitable for being arranged in the engine room of an automobile.

The present invention is not limited to the above-mentioned examples, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the configurations. Further, it is possible to add / delete / replace a part of the configuration of the embodiment with another configuration.

1 ... Humidity measuring device, 1A ... Housing, 1Aa ... Base end side housing member (first housing member), 1Ab ... Tip side housing member (second housing member), 2 ... Introduction guide, 2a ... First introduction guide unit ( 1st wall part), 2b ... 2nd introduction guide part (2nd wall part), 2c ... 1st window part (first circumferential direction gap), 2d ... 2nd window part (2nd circumferential direction gap), 2e ... Radial gap, 2f ... wing shape, 3 ... introduction tube, 3a ... inlet opening, 4 ... humidity detection element, 5 ... measurement room, 6 ... sensor cover, 6a ... recess, 7a ... labyrinth part, 7b ... gas exchange Part, 7c ... Diffusion part, 8a ... Air introduction part, 8b ... Air introduction part, 9a ... Connection terminal, 10 ... Board, 11 ... Intake pipe wall, 12 ... Intake pipe, 13 ... Measurement part accommodation space, Q1 ... Air flow , Q2 ... Air flow.

Claims (7)

Humidity detection element and
A measurement room in which the humidity detection element is arranged and
An introduction pipe that introduces air toward the measurement room,
A partition portion that partitions the introduction pipe and the measurement chamber and is partially provided with a communication passage that communicates the introduction pipe and the measurement chamber.
Humidity measuring device equipped with. In the humidity measuring device according to claim 1,
An air introduction guide arranged on the radial outside of the inlet opening of the introduction pipe is provided.
The introduction guide is a humidity measuring device having a plurality of projecting portions dispersedly arranged all around the entrance opening so as to project from the entrance opening to the side opposite to the side where the measurement chamber is provided. .. In the humidity measuring device according to claim 2.
The introduction guide is arranged as the projecting portion at a position radially inwardly separated from a plurality of first wall surface portions dispersedly arranged around the entire circumference of the entrance opening. A plurality of second wall surface portions dispersedly arranged all around the entrance opening are provided.
The first wall surface portion is provided so that the first window portion and the second wall surface portion formed between two adjacent first wall surface portions overlap in the circumferential direction of the entrance opening.
The second wall surface portion is a humidity measurement provided so that the second window portion formed between two adjacent second wall surface portions and the first wall surface portion overlap in the circumferential direction of the entrance opening. apparatus. In the humidity measuring device according to claim 3,
The introduction pipe is a humidity measuring device having a predetermined length and forming a gas exchange region. In the humidity measuring device according to claim 4,
The measurement room constitutes a diffusion region and
The gas exchange region is a humidity measuring device configured between the diffusion region and the introduction guide. In the humidity measuring device according to claim 5.
A housing having a measurement unit accommodating space and the introduction pipe is provided.
A substrate on which the humidity detection element is mounted and a sensor cover that constitutes the measurement chamber together with the substrate are accommodated in the measurement unit accommodation space.
A humidity measuring device that constitutes the partition portion with the substrate. In the humidity measuring device according to claim 6,
The housing has a first housing member in which the measurement unit accommodation space and a part of the introduction pipe on the side of the measurement unit accommodation space are formed, and the side of the introduction pipe opposite to the side of the measurement unit accommodation space. A humidity measuring device including a second housing member in which a part of the above and the introduction guide is formed.

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