JP7552437B2 - Gas detection equipment - Google Patents

Description

The present invention relates to a gas detection device.

For example, the following Patent Document 1 describes a gas detection device. This gas detection device includes a gas sensor circuit board and a case. The gas sensor circuit board is composed of a printed wiring board and a plurality of electronic components. The plurality of electronic components include, for example, a gas sensor element that detects a predetermined gas (gas concentration) based on a change in electrical resistance value, and a control device (computer device). These electronic components are mounted (soldered) on the printed wiring board. The gas sensor circuit board is housed in a case. The case is provided with a cylindrical portion, and with the gas sensor circuit board housed in the case, the gas sensor element is surrounded by the peripheral wall portion of the cylindrical portion. In other words, the cylindrical portion is an introduction path that leads the atmosphere (gas) of the gas detection device to the gas sensor element.

JP 2008-249684 A

(Problem to be solved by the invention)
In the above-mentioned conventional gas detection device, the outer periphery of the gas sensor circuit board is fixed (locked) by a claw provided on the case. In this state, the tip surface of the cylindrical part of the case is pressed against the surface of the printed wiring board (the periphery of the gas sensor element) and is in close contact with it. As described above, since only the outer periphery of the gas sensor circuit board is supported, the part of the gas sensor circuit board pressed by the cylindrical part is easily deflected. Therefore, according to such a conventional structure, the electrical resistance value of the gas sensor element is affected by the above-mentioned bending of the board, and there is a risk that the gas detection accuracy (accuracy, variation, etc.) will decrease.

The present invention has been made to address the above problems, and its purpose is to provide a gas detection device with improved gas (gas concentration) detection accuracy.

(Means for solving the problem)
In order to achieve the above object, a gas detection device according to the present invention includes a gas sensor circuit board having a printed wiring board and a plurality of electronic components mounted on the printed wiring board, the plurality of electronic components including a gas sensor element for detecting a predetermined gas, and a case for accommodating the gas sensor circuit board. The plurality of electronic components are mounted on one surface of the printed wiring board. The case includes a first member and a second member, the first member having a metal box-shaped portion and a cylindrical portion extending from an outer surface of the box-shaped portion toward the printed wiring board and surrounding the gas sensor element, and the second member abuts against the other surface of the printed wiring board, sandwiches the gas sensor circuit board between the second member and the cylindrical portion, and is fixed to the box-shaped portion to support the gas sensor circuit board.

In a gas detection device according to one aspect of the present invention, the inside of the first member, except for the inside of the cylindrical portion, is filled with a synthetic resin material.

In a gas detection device according to another aspect of the present invention, the cylindrical portion comprises a spacer that is arranged on one side of the printed wiring board and cooperates with the second member to support the gas sensor circuit board .

In a gas detection device according to another aspect of the present invention, the box-shaped portion and the second member are crimped together.

In a gas detection device according to another aspect of the present invention, the second member is a bracket that is fastened to a specified member.

As described above, in the gas detection device of the present invention, the rear surface of the gas sensor circuit board is set flat without any components or component pins, and the plate surface of the plate-shaped second member serving as a support member abuts (is in surface contact with) the rear surface of the gas sensor circuit board 10. Even if the portion of the gas sensor circuit board located around the gas sensor element is pressed by the cylindrical portion, the gas sensor circuit board is unlikely to bend, and the detection accuracy of the gas sensor element is unlikely to be affected. Therefore, according to the present invention, it is possible to improve the gas detection accuracy compared to the case where a conventional support structure for a gas sensor circuit board is adopted.

In another aspect of the gas detection device of the present invention, the cylindrical portion is made of a filter member that allows the gas to be detected to reach the gas sensor element and prevents other gases from reaching the gas sensor element, and one end of the filter member in the central axis direction that is located on the gas sensor circuit board side is open and the other end is closed.

In another aspect of the gas detection device of the present invention, a filter member formed separately from the cylindrical portion, which allows gas to pass through but prevents water droplets from passing through, is arranged to cover the other end surface of the cylindrical portion.

In the gas detection device configured as described above, the cylindrical portion is configured with a filter member that allows the gas to be verified to reach the gas sensor element and prevents other gases from reaching it. Therefore, according to the present invention, the number of parts can be reduced compared to, for example, "a case in which a metallic cylindrical portion is used and a filter member is filled inside," and the parts cost of the product can be reduced.

1 is a perspective view of a gas detection device according to a first embodiment of the present invention, as viewed from the front side. 1B is a perspective view of the gas detection device of FIG. 1A as viewed from the back side. This is a cross-sectional view of FIG. 1A along line II-II. FIG. 1B is an exploded perspective view of the gas detection device of FIG. FIG. 2 is a perspective view of a gas sensor circuit board. FIG. 2 is an exploded perspective view of a filter case and a filter member. FIG. 4 is a cross-sectional view of a gas detection device according to a second embodiment of the present invention. 11 is a perspective view showing a process of attaching a filter to a main body of the case. FIG. FIG. 11 is a perspective view showing a process of attaching the gas sensor circuit board to the case. 11 is a perspective view showing a process of attaching a bracket to a main body of the case. FIG.

First Embodiment
A gas detection device 1 according to a first embodiment of the present invention will be described below (see Figs. 1A and 1B). The gas detection device 1 is disposed, for example, in a battery device of a vehicle (electric vehicle). In this example, when a storage battery constituting the battery device falls into an abnormal state and a specific gas (for example, a component of the electrolyte of the battery, hydrogen, etc.) is released from the storage battery, the gas detection device 1 detects the gas and notifies the detection result to a control device (ECU) of the vehicle.

The specific configuration of the gas detection device 1 will be described below. As shown in Figures 1A and 1B, the gas detection device 1 has a substantially rectangular plate shape. In the following description, the plate thickness direction of the gas detection device 1 will be referred to as the up-down direction. In addition, the extension direction of one of the two sides of the gas detection device 1 perpendicular to the up-down direction will be referred to as the front-back direction, and the extension direction of the other side will be referred to as the left-right direction.

The gas detection device 1 comprises a gas sensor circuit board 10 and a case 20, and the gas sensor circuit board 10 is housed within the case 20 (see Figures 2 and 3).

The gas sensor circuit board 10 is composed of a printed wiring board 11 and multiple electronic components 12 (see Figure 4).

The printed wiring board 11 is a multi-layer board (e.g., a board having two or more layers). The printed wiring board 11 is approximately rectangular. Inside the case 20, the board thickness direction of the printed wiring board 11 coincides with the up-down direction. In addition, one side of the printed wiring board 11 coincides with the front-rear direction, and the other side coincides with the left-right direction. Copper foil patterns such as multiple signal lines and power lines (positive electrode planes) are formed on each layer (surface layer and inner layer) of the printed wiring board 11. However, the back layer of the printed wiring board 11 is a ground plane that serves as the negative electrode (reference potential) of the power supply. Multiple electronic components 12, which will be described next, are mounted (soldered) on the surface layer of the printed wiring board 11, and no components are mounted on the back layer.

The electronic components 12 include a gas sensor element 12a, a control device 12b, a connector 12c, and the like. The configuration of the gas sensor element 12a is the same as that of a known gas sensor element. That is, the gas sensor element 12a includes a heat generating portion, a detection portion, and the like, and is configured so that the electrical resistance value of the detection portion changes depending on the state of the atmosphere (gas). The control device 12b is a microchip with a built-in arithmetic unit, a storage device, a timer, and the like. The control device 12b controls the power supply (current pattern) to the heat generating portion of the gas sensor element 12a, and detects the change in the electrical resistance value (terminal voltage) of the detection portion of the gas sensor element 12a. The connector 12c includes a plurality of contact pins and a housing. Several pins among the plurality of contact pins are electrically connected to the signal line (wiring pattern for communication signals) of the printed wiring board 11, and the remaining pins are electrically connected to the power supply line. Note that most of the housing of the connector 12c protrudes outward (forward) from the outer periphery of the printed wiring board 11. The electronic components 12 are surface-mounted components, and their pins do not protrude from the back side of the printed wiring board 11. However, a part of the housing of the connector 12c (the protruding part for fixing) is pressed into a through hole provided in the printed wiring board 11 and protrudes slightly from the back side of the printed wiring board. In other words, most of the back side of the printed wiring board 11 (excluding the protruding part for fixing the connector 12c) is flat (see Figure 3).

One end of a wire harness (not shown) is connected to the connector 12c, and the other end of the wire harness is connected to the vehicle's control device (ECU). Power is supplied to the gas detection device 1 via this wire harness, and gas detection results (i.e., information about the battery state) are transmitted and received between the control device 12b of the gas detection device 1 and the control device (ECU) of the vehicle body.

A circular urethane seal ring R (spacer (see Figure 3)) is attached to the printed wiring board 11 so as to surround the gas sensor element 12a mounted on the surface of the gas sensor circuit board 10.

The case 20 comprises a main body 21, a filter case 22, and a bracket 23 (see FIG. 3). The main body 21 is made of metal (e.g., stainless steel). The main body 21 is a shallow box-shaped portion. The main body 21 is open downwards. That is, the main body 21 comprises an upper wall portion 211 and a peripheral wall portion 212. The upper wall portion 211 is a rectangular plate-shaped portion. The front-rear and left-right dimensions of the upper wall portion 211 are slightly larger than the front-rear and left-right dimensions of the printed wiring board 11.

The upper wall portion 211 is formed with a cylindrical support portion _SP211 that supports a filter case 22, which will be described later. The support portion _SP211 is disposed at a position slightly shifted rearward from the center of the upper wall portion 211. The support portion _SP211 extends downward from the upper wall portion 211, and its upper and lower ends are open upward and downward, respectively. In the gas detection device 1, the lower end of the support portion _SP211 faces the gas sensor element 12a of the gas sensor circuit board 10 (see FIG. 2).

The peripheral wall portion 212 is composed of four side wall portions W1 to W4 each extending downward from the outer periphery of the upper wall portion 211. The side wall portion W1 and the side wall portion W3 are spaced apart in the front-rear direction and are arranged facing each other. The side wall portion W3 and the side wall portion W4 are spaced apart in the left-right direction and are arranged facing each other. Small pieces W3a, W3a protruding downward are formed on the lower end surface of the side wall portion W3 (the end surface opposite the upper wall portion 211). The small pieces W3a, W3a are spaced apart in the front-rear direction. The side wall portion W4 is also formed with small pieces W4a, W4a, like the side wall portion W3.

The filter case 22 has a cylindrical shape that extends in the vertical direction. The outer diameter of the filter case 22 is approximately the same as the inner diameter of the support part SP _211. A flange part 22F is provided at the lower end of the filter case 22 (see FIG. 5). The filter case 22 is filled with various filter members that allow only the gas to be detected to pass and block other gases as much as possible (see FIG. 5).

The filter case 22 is inserted into the support part _SP211 (see FIG. 2). The upper surface of the flange part 22F abuts against the lower end surface of the support part _SP211 (see FIG. 2). The lower surface of the flange part 22F and the seal ring R are arranged coaxially, and the seal ring R is slightly deformed and in close contact with the lower surface of the flange part 22F. The part consisting of the support part _SP211 , the filter case 22, and the seal ring R corresponds to the cylindrical part of the present invention. In other words, the gas sensor element 12a is surrounded by the cylindrical part.

The bracket 23 is a generally rectangular plate-like member extending in the left-right direction (see FIG. 3). The plate thickness direction of the bracket 23 coincides with the up-down direction. The front-rear dimension of the bracket 23 is smaller than the front-rear dimension of the main body 21. The left-right dimension of the bracket 23 is larger than the left-right dimension of the main body 21. That is, in the gas detection device 1, both ends of the bracket 23 in the longitudinal direction (hereinafter referred to as flange portions 23F, 23F) protrude to the left and right from the main body 21.

In the gas detection device 1, a portion of the bracket 23 excluding the flange portions 23F, 23F (a portion between the flange portions 23F, 23F; hereinafter, this portion will be referred to as the support portion 23S) abuts (makes surface contact with) the rear surface of the gas sensor circuit board 10 to support the gas sensor circuit board 10. Slit-shaped through holes TH _23S , TH _23S extending in the front-rear direction are formed at the left and right ends of the support portion 23S, respectively (see FIG. 3). The through holes TH _23S , TH _23S correspond to the small piece portions W3a, W3a and the small piece portions W4a, W4a of the main body portion 21, respectively, and the small piece portions W3a, W3a and the small piece portions W4a, W4a are inserted into the through holes TH _23S , TH _23S and bent (crimped). In this manner, the main body portion 21 and the bracket 23 are fastened together.

A step is formed between the support portion 23S and the flange portions 23F, 23F near the boundary between the support portion 23S and the flange portions 23F, 23F. That is, the flange portions 23F, 23F are located slightly below the support portion 23S. A circular through hole TH _23F is formed in the flange portion 23F. A fastening member (not shown) is inserted into this through hole TH _23F , and its tip is fastened to the battery device of the electric vehicle. In this manner, the bracket 23 (gas detection device 1) is fixed to the battery device of the vehicle.

The case 20 is filled with a synthetic resin material (e.g., rim material, thermosetting resin material, etc.) (see FIG. 2). This fixes the gas sensor circuit board 10 to the case 20.

The gas detection device 1 described above is assembled as follows. As described below, in each process, the components are turned upside down. In other words, the up-down direction of the components is set opposite to that shown in FIG. 3.

First, the main body 21 of the case 20 is turned upside down (with the opening facing upward). Then, the filter case 22 is inserted into the support portion SP ₂₁₁ of the main body 21. Next, the gas sensor circuit board 10 is inserted into the main body 21. At this time, the gas sensor circuit board 10 is positioned so that the connector 12c protrudes outward from the main body 21 through the cutout portion CP and the central axis of the seal ring R coincides with that of the flange portion 22F. The seal ring R is slightly deformed by the weight of the gas sensor circuit board 10.

Next, the bracket 23 is brought close to the main body 21 and the gas sensor circuit board 10, and the small pieces W3a, W3a and the small pieces W4a, W4a are inserted into the through holes _TH22S , _TH22S . Then, the small pieces W3a, W3a and the small pieces W4a, W4a are bent (crimped). Finally, the synthetic resin material A is injected into the main body 21 and left until the synthetic resin material A hardens. A groove is provided on the outer periphery of the connector 12c, and the peripheral edge of the notch CP is inserted into this groove and adheres closely. This prevents the synthetic resin material A from leaking from the notch CP. In the above manner, the gas detection device L is assembled. When a thermosetting resin material is used as the synthetic resin material A for fixing the gas sensor circuit board 10, the gas sensor circuit board 10 and the case 20 are heated to harden the thermosetting resin material.

As described above, in the gas detection device 1, the flange portion 22F of the filter case 22 abuts against the seal ring R arranged around the gas sensor element 12a, and the seal ring R is slightly deformed. That is, the gas sensor circuit board 10 is pressed downward (toward the bracket 23) by the filter case 22 through the seal ring R. This prevents gas that has passed through the filter and reached the gas sensor element 12a from entering the main body 21. Here, the back surface of the gas sensor circuit board 10 is set to be flat without any components or component pins, and the plate surface of the plate-shaped bracket 23 as a support member abuts (surface contacts) against the back surface of the gas sensor circuit board 10. Therefore, even if the gas sensor circuit board 10 is pressed downward to the extent that the seal ring R is slightly deformed, the gas sensor circuit board 10 is unlikely to bend and is unlikely to affect the detection accuracy of the gas sensor element 12a. Therefore, according to this embodiment, the gas detection accuracy can be improved compared to the case where a conventional support structure for a gas sensor circuit board is adopted.

In addition, because the gas sensor circuit board 10 is housed in a metal case 20, the electronic components that make up the gas sensor circuit board 10 are less susceptible to external noise (electromagnetic noise generated by the battery device), and malfunction of these electronic components can be suppressed. In addition, the electronic components 12 are mounted on only one side of the printed wiring board 11. Therefore, the mounting cost is lower than when the electronic components 12 are mounted on both sides of the printed wiring board 11.

Second Embodiment
Next, a gas detection device 1A according to a second embodiment of the present invention will be described. Gas detection device 1A employs a case 20A instead of case 20 of gas detection device 1 of the first embodiment. That is, gas detection device 1A includes a gas sensor circuit board 10 and a case 20A. Since the configuration of gas sensor circuit board 10 is the same as that of the first embodiment, a description thereof will be omitted, and the configuration of case 20A will be described below.

In place of the main body 21 and filter case 22 of the case 20, the case 20A employs a main body 21A and a filter 22A. That is, the case 20A comprises a main body 21A, a filter 22A, and a bracket 23. The configuration of the bracket 23 is the same as in the first embodiment, so a description thereof will be omitted, and the configuration of the main body 21A and the filter 22A will be described below.

The main body 21A is made of metal (e.g., stainless steel). The main body 21A is a shallow box-shaped portion. The main body 21A is open downwards. That is, the main body 21A has an upper wall portion 211A and a peripheral wall portion 212A. The upper wall portion 211A is a rectangular plate-shaped portion. The front-rear and left-right dimensions of the upper wall portion 211A are slightly larger than the front-rear and left-right dimensions of the printed wiring board 11.

The upper wall portion 211A is formed with a support portion SP _211A that supports a filter 22A (described later). The support portion SP _211A is a portion that is formed by pressing (drawing) a portion of the upper wall portion 211A upward to slightly protrude upward from the upper surface of the upper wall portion 211A. In a plan view of the main body portion 21A, the support portion SP _211A has a circular shape. A through hole TH _211A is formed in the center of the support portion SP _211A .

In the gas detection device 1, the support portion SP _211A is located above the gas sensor element 12a of the gas sensor circuit board 10 (see FIG. 6).

The peripheral wall portion 212A is composed of four side walls W1 to W4 similar to the main body portion 21 of the first embodiment (see FIG. 7A).

Filter 22A includes waterproof filter 22A1 and gas filter 22A2.

The waterproof filter 22A1 has a disk shape. The outer diameter of the waterproof filter 22A1 is slightly smaller than the inner diameter of the support part SP _211A . The waterproof filter 22A1 is made of, for example, expanded PTFE (polytetrafluoroethylene) material. The waterproof filter 22A1 allows gas and moisture to enter the main body part 21A, and prevents water droplets and water from entering.

The gas filter 22A2 has a cylindrical shape extending in the vertical direction. The lower end (one end) of the gas filter 22A2 is open, and the upper end (the other end) is closed (see FIG. 6). The outer diameter of the gas filter 22A2 is equal to or slightly larger than the _{inner diameter of the support part SP 211A .} The gas filter 22A2 is formed, for example, by impregnating a cylindrical base material made of nonwoven fabric with silica gel (see, for example, Japanese Patent Application No. 2002-205659). The gas filter 22A2 allows the gas to be detected to reach the gas sensor element 12a, and inhibits the reach of other gases.

The gas detection device 1A described above is assembled as follows. In each step, the components are turned over, as described below.

First, the main body 21A of the case 20 is set upside down (with the opening facing upward). Then, the waterproof filter 22A1 is inserted into the support part SP _211A of the main body 21A (see FIG. 7A). Next, the other end (the closed end) of the gas filter 22A2 is lightly press-fitted into the support part SP _211A . That is, the waterproof filter 22A1 covers the other end face of the gas filter 22A2.

Next, as in the first embodiment, the gas sensor circuit board 10 is inserted into the main body 21A (see FIG. 7B). In the first embodiment, the seal ring R surrounding the gas sensor element 12a is attached to the printed wiring board 11 in advance, but in the second embodiment, the seal ring R is not necessary. In this state, the end face (the end face of the open end) of the gas filter 22A2 abuts against the surface of the printed wiring board 11, and the gas sensor element 12a is housed within that end. One end of the gas filter 22A2 is slightly deformed due to the weight of the gas sensor circuit board 10.

Next, as in the first embodiment, the bracket 23 is attached to the main body 21A (see FIG. 7C). Finally, the synthetic resin material A is injected into the main body 21A and left until the synthetic resin material A hardens.

As described above, in the first embodiment, the filter member is housed in the cylindrical metal filter case 22, but in the second embodiment, the gas filter 22A2 itself is formed in a cylindrical shape, and the gas filter 22A2 constitutes a passage (duct) for guiding the gas to be detected to the gas sensor element 12a. Therefore, according to this embodiment, the filter case 22 in the first embodiment is not necessary. Furthermore, since the gas filter 22A2 is made of a material based on an elastic nonwoven fabric, one end face of the gas filter 22A2 abuts against the printed wiring board 11, and the end is slightly elastically deformed. As a result, one end face of the gas filter 22A2 is in close contact with the printed wiring board 11. Therefore, the seal ring R in the first embodiment is not necessary. Therefore, according to this embodiment, the number of parts can be reduced compared to the first embodiment, and the parts cost of the product can be reduced.

Furthermore, the implementation of the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the purpose of the present invention.

For example, the bracket 23 may be formed to be equal to or larger than the area of the printed wiring board. This can more effectively suppress deformation of the printed wiring board and make it less susceptible to the effects of electromagnetic noise.

In addition, instead of the bracket 23, a simple flat plate that does not have the function of fixing to other support members may be used.

In the first and second embodiments, the gas sensor circuit board 10 is fixed using a thermosetting resin material. Alternatively, a cushioning material having elasticity may be sandwiched between the gas sensor circuit board 10 and the upper wall portion 211 (211A) of the main body portion 21 (21A), and the gas sensor circuit board 10 may be fixed by pressing the gas sensor circuit board 10 toward the bracket 23 using the elasticity of the cushioning material. In this case, it is preferable to coat the electronic components mounted on the gas sensor circuit board 10 (especially those having multiple terminals with relatively narrow spacing between them) with a synthetic resin material to prevent short-circuiting between the terminals due to the generation of whiskers.

Also, for example, in the first embodiment, the portion consisting of the upper wall portion 211, the support portion SP ₂₁₁ , the filter case 22, and the seal ring R may be integrally formed.

1, 1A...gas detector, 10...gas sensor circuit board, 11...printed wiring board, 12...electronic component, 12a...gas sensor element, 12b...controller, 12c...connector, 20, 20A...case, 21, 21A...main body (first member), 22...filter case (first member), 22F...flange, 23...bracket (second member), 23F...flange, 23S...support, 22A...filter (first member), R...seal ring

Claims (7)

a gas sensor circuit board having a printed wiring board and a plurality of electronic components mounted on the printed wiring board, the plurality of electronic components including a gas sensor element for detecting a predetermined gas;
a case for accommodating the gas sensor circuit board;
A gas detection device comprising:
The plurality of electronic components are mounted on one surface of the printed wiring board,
the case includes a first member and a second member,
The first member is
a metal box-shaped portion covering one surface of the printed wiring board and opening to the other surface;
a cylindrical portion extending from an outer surface of the box-shaped portion toward the printed wiring board and surrounding the gas sensor element;
having
The second member is
abutting against the other surface of the printed wiring board, sandwiching the gas sensor circuit board between the cylindrical portion and the first member, and being fixed to the first member to support the gas sensor circuit board;
Gas detection equipment. 2. The gas detection device according to claim 1,
A gas detection device, wherein an inside of the first member, excluding an inside of the cylindrical portion, is filled with a synthetic resin material. 2. The gas detection device according to claim 1,
The gas detection device comprises a spacer, the cylindrical portion being arranged on one surface side of the printed wiring board, the spacer cooperating with the second member to support the gas sensor circuit board . The gas detection device according to any one of claims 1 to 3,
The gas detection device, wherein the box-shaped portion and the second member are connected by crimping. The gas detection device according to any one of claims 1 to 4,
The gas detection device, wherein the second member is a bracket that is fastened to a predetermined member. 6. The gas detection device according to claim 1,
the tubular portion is composed of a filter member that allows the gas to be detected to reach the gas sensor element and suppresses the reach of other gases, and one end of the tubular portion in the central axial direction, which is located on the gas sensor circuit board side, is open and the other end is closed. 7. The gas detection device according to claim 6,
A gas detection device comprising a filter member formed separately from the cylindrical portion, the filter member allowing gas to pass through and suppressing the passage of water droplets, and arranged to cover the other end surface of the cylindrical portion.

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