JP7070472B2 - Temperature sensor - Google Patents

Description

The present invention relates to a temperature sensor.

The temperature sensor described in Patent Document 1 is arranged in a hydrogen tank of a fuel cell vehicle and detects the temperature in the hydrogen tank. The filling speed of hydrogen in the hydrogen tank is controlled based on the detection result of the temperature in the hydrogen tank by the temperature sensor.

Here, if the temperature-sensitive element for detecting the temperature in the temperature sensor is exposed to the hydrogen atmosphere in the hydrogen tank, the temperature-sensitive element may be reduced and deteriorated, and the accuracy of temperature detection by the temperature sensor may decrease. be. Further, since an impact and pressure are generated in the hydrogen tank due to the filling of hydrogen, it is necessary to protect the temperature sensitive element from these impacts and pressure.

Therefore, in the temperature sensor described in Patent Document 1, the temperature sensitive element is covered with a glass encapsulant made of glass, so that the temperature sensitive element is separated from the atmosphere in the hydrogen tank. This prevents the temperature-sensitive element from being exposed to the hydrogen atmosphere in the hydrogen tank, and also prevents the above-mentioned impact and pressure from being directly applied to the temperature-sensitive element.

Japanese Unexamined Patent Publication No. 2016-305446

Here, since the resin has high airtightness and pressure resistance and is cheaper than the glass material, it is conceivable to change the glass encapsulant to a resin encapsulant. However, in this case, there is a problem described below.

When the hydrogen tank is filled with hydrogen, the pressure inside the hydrogen tank becomes high. As the pressure in the hydrogen tank rises, the amount of hydrogen dissolved in the resin encapsulation body of the temperature sensor arranged in the hydrogen tank increases. In particular, hydrogen tends to be rapidly increased in bubbles (voids) formed during resin molding.

Then, as the hydrogen in the hydrogen tank is used for running the fuel cell vehicle, the hydrogen in the hydrogen tank is reduced and the inside of the hydrogen tank is depressurized. With this depressurization, hydrogen dissolved in the resin encapsulant vaporizes inside the resin encapsulant, and bubbles and cracks originating from the bubbles may occur in the resin encapsulant. This phenomenon is called blister destruction.

It is considered that the cracks generated in the resin encapsulant due to the blister fracture become open cracks extending to the surface of the resin encapsulant. When an opening crack occurs in the resin encapsulating body, hydrogen may be introduced to the vicinity of the temperature-sensitive element through the opening crack, and the temperature-sensitive element may be reduced and deteriorated. When the temperature-sensitive element is reduced and deteriorated, the temperature detection accuracy by the temperature sensor may decrease.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a temperature sensor in which an opening crack is unlikely to occur in a resin partition portion for separating an atmosphere in a hydrogen tank and a temperature sensitive element.

One aspect of the present invention is a temperature sensor (1) arranged in a hydrogen tank.
A temperature-sensitive element (2) for detecting temperature,
A pair of element electrode wires (3) electrically connected to the temperature-sensitive element, and
A resin partition portion (4) for separating the atmosphere in the hydrogen tank and the temperature sensitive element is provided.
The resin partition portion has a sealing portion (4a) in which the temperature-sensitive element is directly embedded therein.
The sealing portion contains a large number of inorganic fibers (42) in the resin (41).
A large number of the inorganic fibers are located in a temperature sensor in which the longitudinal directions of the respective inorganic fibers are arranged so as to be three-dimensionally random directions.

In the temperature sensor of the above aspect, the large number of inorganic fibers contained in the resin partition are arranged so that the longitudinal direction of each inorganic fiber is three-dimensionally random. Therefore, even if bubbles and cracks originating from the bubbles occur in the resin partition due to the pressure in the hydrogen tank being reduced from the high pressure state, the developed cracks are still in the resin partition. Further progress is suppressed by reaching the inorganic fibers of. Therefore, it is possible to suppress the occurrence of open cracks formed by the growth of cracks up to the surface of the resin partition portion.

As described above, according to the above aspect, it is possible to provide a temperature sensor in which an opening crack is unlikely to occur in the resin partition portion for separating the atmosphere in the hydrogen tank and the temperature sensitive element.
The reference numerals in parentheses described in the scope of claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. It's not a thing.

The front view of the temperature sensor in Embodiment 1. The cross-sectional view of the sealing part observed with the scanning electron microscope in Embodiment 1. FIG. The figure which represented FIG. 2 schematically. The schematic diagram for demonstrating the fiber angle θ in Embodiment 1. FIG. The cross-sectional view which shows the effect in Embodiment 1. FIG. The schematic diagram which shows the appearance that the opening crack occurred in the comparative form. FIG. 2 is a cross-sectional view of a temperature sensitive element, an element electrode wire, a sealing portion, and an outer surrounding portion in the second embodiment. Sectional drawing of the temperature sensitive element, the element electrode wire, the sealing part, and the outer surrounding part in a reference form .

(Embodiment 1)
The embodiment of the temperature sensor will be described with reference to FIGS. 1 to 6.
The temperature sensor 1 of the present embodiment is arranged and used in a hydrogen tank.

As shown in FIG. 1, the temperature sensor 1 includes a temperature-sensitive element 2, a pair of element electrode wires 3, and a resin partition portion 4. The temperature sensitive element 2 detects the temperature inside the hydrogen tank. The pair of element electrode wires 3 are electrically connected to the temperature sensitive element 2. The resin partition portion 4 separates the atmosphere inside the hydrogen tank from the temperature sensitive element 2.

As shown in FIG. 3, the resin partition portion 4 contains a large number of inorganic fibers 42 in the resin 41. The large number of inorganic fibers 42 are arranged so that the longitudinal direction of each inorganic fiber 42 is three-dimensionally random.
Hereinafter, this embodiment will be described in detail.

Hereinafter, the direction in which the central axis of the temperature sensor 1 extends is referred to as the X direction. Further, the side of one side in the X direction to which the temperature sensitive element 2 is connected in the pair of element electrode wires 3 is referred to as the tip end side, and the opposite side is referred to as the base end side.

The temperature sensor 1 of this embodiment is mounted in a hydrogen tank used in, for example, a fuel cell vehicle (so-called FCV; Fuel Cell Vehicle) or the like. The filling speed of hydrogen in the hydrogen tank is controlled based on the detection result of the temperature in the hydrogen tank by the temperature sensor 1. Since the hydrogen tank is filled with hydrogen, an impact and a pressure are generated, and the temperature sensor 1 is designed to have a strength that can withstand this.

In addition, the pressure inside the hydrogen tank becomes high when hydrogen is filled. When the inside of the hydrogen tank is in a high pressure state, the hydrogen gas in the hydrogen tank dissolves in the resin 41 constituting the resin partition portion 4 of the temperature sensor 1. As the hydrogen in the hydrogen tank is used for running the fuel cell vehicle from there, the hydrogen in the hydrogen tank is reduced and the inside of the hydrogen tank is depressurized. Along with this depressurization, the hydrogen dissolved in the resin 41 of the resin partition 4 tries to pass through the inside of the resin 41 to the outside of the resin partition 4, but a part of the hydrogen dissolved in the resin 41 is present. It is conceivable that the resin 41 cannot escape from the resin 41, and bubbles and cracks starting from the bubbles may occur inside the resin partition portion 4. The temperature sensor 1 of the present embodiment is devised so that the crack does not reach the surface of the resin partition portion 4.

The temperature sensing element 2 of the temperature sensor 1 is composed of, for example, a thermistor. Not limited to this, the temperature sensitive element 2 can also be configured by a thermocouple, a resistance temperature measuring resistor made of platinum, or the like. As shown in FIG. 1, the temperature sensitive element 2 is fixed in a state of being sandwiched by the tip portions of the pair of element electrode wires 3.

The pair of element electrode wires 3 are formed of, for example, a platinum alloy in a linear shape. The pair of element electrode wires 3 are arranged side by side so as to be parallel to each other. Then, a sealing portion 4a is formed so as to embed the temperature-sensitive element 2 and the tip portions of the pair of element electrode wires 3 inside.

The sealing portion 4a constitutes the resin partition portion 4 described above. That is, the sealing portion 4a separates the temperature sensitive element 2 from the hydrogen atmosphere in the hydrogen tank.

The sealing portion 4a contains the inorganic fiber 42 in the resin 41. For example, the sealing portion 4a is made of a polyamide resin such as PA66 or a polyphenylene sulfide resin (that is, a PPS resin) containing an inorganic fiber 42 such as a glass fiber.

As shown in FIG. 3, each inorganic fiber 42 contained in the sealing portion 4a has a long columnar shape. The large number of inorganic fibers 42 are arranged so that the longitudinal direction of each inorganic fiber 42 is three-dimensionally random. That is, the longitudinal directions of the inorganic fibers 42 are not aligned in one direction. For example, if the longitudinal directions of the majority of the inorganic fibers 42 are aligned in one direction and the longitudinal directions of the remaining few inorganic fibers 42 are oriented in the direction intersecting the one direction, each inorganic fiber It is not said that the longitudinal direction of 42 is oriented in a three-dimensionally random direction.

Whether or not the longitudinal direction of each inorganic fiber 42 in the sealing portion 4a is a three-dimensionally random direction is determined by, for example, polishing a cross section obtained by cutting the sealing portion 4a and scanning the cross section with a scanning electron microscope (a scanning electron microscope). That is, it can be grasped by observing with SEM; Scanning Electron Microscope). FIG. 2 shows a cross section observed by SEM. Further, FIG. 3 is a schematic view of a cross section of the sealing portion 4a observed by SEM. In FIG. 3, the inorganic fiber 421 appearing in a long square shape is a cross section obtained by cutting the inorganic fiber 421 in parallel in the longitudinal direction of the inorganic fiber 421. In FIG. 3, the circular inorganic fiber 422 shows a cross section obtained by cutting the inorganic fiber 422 in the radial direction of the inorganic fiber 422. In FIG. 3, the cross section of the inorganic fiber 423 appearing in an elliptical shape is a cross section obtained by cutting the inorganic fiber 423 in an oblique direction inclined with respect to the longitudinal direction of the inorganic fiber 423.

Further, for example, it is possible to three-dimensionally observe the inorganic fiber 42 of the sealing portion 4a by X-ray CT scan. In the X-ray CT scan, the cross-sectional layer obtained by cutting the sealing portion 4a in the direction orthogonal to the specific direction is imaged by X-ray CT at several hundred points in the specific direction. Then, by stacking the cross-sectional layers at several hundred places in the specific direction, it is possible to observe the inorganic fiber 42 of the three-dimensional sealing portion 4a. Here, since the resin is generally composed of relatively light elements such as carbon, hydrogen, oxygen, and nitrogen, the X-ray absorption rate is low. Therefore, in an image obtained by X-ray CT scan of only the resin member, the contrast is often not clearly formed in the resin member. On the other hand, when a glass-containing resin containing glass fibers is photographed by X-ray CT, the glass fibers are composed of silicon, so that between the relatively light elements constituting the resin member and the glass fibers composed of silicon. It has a clear contrast. Therefore, it is possible to observe the inorganic fiber 42 of the sealing portion 4a by X-ray CT scan.

As shown in FIG. 4, in an arbitrary cross section of the sealing portion 4a, when a virtual straight line L extending in an arbitrary direction is drawn, an angle of 90 ° or less formed between each inorganic fiber 42 and the virtual straight line L is formed by the fiber. Let the angle θ be. At this time, in an arbitrary cross section, the average of the fiber angles θ of each of the large number of inorganic fibers 42 is 10 ° (= 10 (π / 180) rad) or more. That is, in any arbitrary cross section, the average of the fiber angles θ, which are angles of 90 ° or less between the virtual straight line L in all directions and each inorganic fiber 42, is 10 ° or more. When the average of the fiber angles θ described above is 10 ° or more, the upper limit of the average of the fiber angles θ is geometrically 80 °. Note that FIG. 4 is a schematic view of a cross section of the sealing portion 4a observed by SEM, showing only the inorganic fibers 42 (see reference numeral 421 in FIG. 3) appearing in a long square shape in FIG. Is.

For the average of the above-mentioned fiber angles θ, at least 20 inorganic fibers 42 are randomly selected from the long square-shaped inorganic fibers 42 appearing in an arbitrary cross section as shown in FIG. 4, and the at least 20 fiber angles are selected. It can be the average of θ. Randomly selecting at least 20 inorganic fibers 42 appearing in an arbitrary cross section means that the longitudinal directions are all parallel to the virtual straight line L even though the inorganic fibers 42 having various large and small fiber angles θ are present in the arbitrary cross section. Alternatively, the case where the substantially parallel inorganic fibers 42 are intentionally selected is excluded. That is, when inorganic fibers 42 having various large and small fiber angles θ appear in an arbitrary cross section, the average of the fiber angles θ is that both the inorganic fibers 42 having a relatively large fiber angle θ and the inorganic fibers 42 having a relatively small fiber angle θ At least 20 inorganic fibers 42 contained therein can be arbitrarily selected and obtained by averaging these fiber angles θ.

When a bubble is contained in the sealing portion 4a, the half-line is configured to always pass through the inorganic fiber 42 when an arbitrary half-line starting from the bubble is drawn in an arbitrary cross section passing through the bubble. Is preferable. As a result, even if a crack should occur in the sealing portion 4a, it is easy to prevent the crack from extending to the surface of the sealing portion 4a.

The content of the inorganic fiber 42 in the sealing portion 4a is 10 wt% or more and 40 wt% or less. Further, in the sealing portion 4a, the average length of a large number of inorganic fibers 42 is 30 μm or more and 250 μm or less. The length of the inorganic fiber 42 is measured, for example, in the cross section of the inorganic fiber 42 appearing in the cross section of the polished sealing portion 4a, the length of the inorganic fiber 42 appearing in a long square shape instead of a circular or elliptical shape. It can be done by measuring. A manufacturing method for making the longitudinal direction of each inorganic fiber 42 three-dimensionally random in the sealing portion 4a will be described later.

Although not shown, a conductive member is connected to each element electrode wire 3 protruding from the sealing portion 4a toward the proximal end side. The temperature sensing element 2 is electrically connected to an external device of the temperature sensor 1 via a conductive member. Although not shown, the temperature-sensitive element 2 and the pair of element electrode wires 3 are held in the housing and surrounded by a cover fixed to the housing. A through hole is formed in the wall portion constituting the cover, and when the temperature sensor 1 is used, hydrogen gas to be measured by the temperature of the temperature sensor 1 passes around the sealing portion 4a in the cover through the through hole. Will be introduced to.

Next, a method for manufacturing the sealing portion 4a will be described.
The sealing portion 4a can be formed by dipping, injection molding, or the like. At this time, it is necessary to devise a manufacturing method so that the longitudinal direction of each inorganic fiber 42 in the sealing portion 4a is a three-dimensionally random direction.

First, a method of forming the sealing portion 4a by dipping will be described.
The resin material constituting the resin 41 of the sealing portion 4a is heated to a liquid state. Then, the inorganic fiber 42 is put in the liquid resin material, and the inorganic fiber 42 is well dispersed in the resin material to form a dip liquid. Here, by well dispersing the inorganic fibers 42 in the resin 41, the longitudinal direction of each inorganic fiber 42 in the resin 41 becomes a three-dimensionally random direction.

Then, the portion of the temperature sensor 1's temperature-sensitive element 2 and the pair of element electrode wires 3 covered by the sealing portion 4a is dipped into the dip liquid, and the dip liquid is adhered to the surface of the portion. At this time, if no special measures are taken, the dip liquid adhering to the temperature sensitive element 2 and the element electrode wire 3 after the dip tends to drip due to gravity, and when the dip liquid drips, the direction of the inorganic fiber 42 is oriented in the direction of gravity. It's easy to do.

Therefore, in the present embodiment, the amount of the solvent in the dip liquid is appropriately adjusted so that the viscosity of the dip liquid becomes relatively high. As a result, the dip liquid covering the temperature sensitive element 2 and the element electrode wire 3 can be prevented from dripping after dipping, and the inorganic fibers 42 in the dip liquid covering the surfaces of the temperature sensitive element 2 and the element electrode wire 3 can be formed. It becomes easier to maintain a highly dispersed state.

Further, in the present embodiment, the speed at which the temperature sensitive element 2 and the pair of element electrode wires 3 are pulled up from the dip liquid at the time of dipping is relatively high. As a result, the time for pulling up the temperature-sensitive element 2 and the pair of element electrode wires 3 from the dip liquid can be shortened, and the dip liquid covering the temperature-sensitive element 2 and the element electrode wires 3 is less likely to drip after dipping. This also makes it easier to maintain a highly dispersed state of the inorganic fibers 42 in the dip liquid covering the surfaces of the temperature sensitive element 2 and the element electrode wire 3.

Then, after the temperature-sensitive element 2 and the pair of element electrode wires 3 are pulled up from the dip liquid, the dip liquid adhering to the temperature-sensitive element 2 and the pair of element electrode wires 3 is dried. As a result, the dip liquid is solidified and the sealing portion 4a is formed. From the above, it is possible to obtain the sealing portion 4a arranged so that the longitudinal direction of each inorganic fiber 42 is three-dimensionally random.

Next, a method of forming the sealing portion 4a by injection molding will be described.
A portion of the temperature-sensitive element 2 and the pair of element electrode wires 3 covered by the sealing portion 4a is arranged in the mold constituting the sealing portion 4a. Then, a mixed material obtained by heating and melting the resin material constituting the resin 41 of the sealing portion 4a and the inorganic fiber 42 is produced, and this is injected into the mold. After that, the mixed material injected into the mold is cooled to solidify it to form the sealing portion 4a.

At this time, if no special measures are taken, the orientation of the inorganic fibers 42 in the mixed material is likely to be oriented in the injection direction of the mixed material in injection molding, and the longitudinal direction of each inorganic fiber 42 is randomly formed three-dimensionally. Can't be done.

Therefore, in the present embodiment, after the mixed material is injected into the mold, the time until the mixed material is completely solidified is secured longer than usual. This can be achieved, for example, by slowing the cooling of the mixture more than usual. This makes it possible to prolong the state in which the mixed material is liquid (that is, the state in which it has fluidity) in the mold. Therefore, even if the direction of the inorganic fibers 42 contained in the mixed material is oriented in the injection direction immediately after the mixed material is injected into the mold, each inorganic fiber 42 flows in the mixed material with the passage of time thereafter. However, the longitudinal direction of each inorganic fiber 42 is three-dimensionally random. By solidifying the mixed material in this state, it is possible to obtain a sealing portion 4a arranged so that the longitudinal direction of each inorganic fiber 42 is three-dimensionally random.

By the method exemplified above, it is possible to manufacture the sealing portion 4a in which the longitudinal direction of each inorganic fiber 42 is three-dimensionally random.

Next, the action and effect of this embodiment will be described.
In the temperature sensor 1 of the present embodiment, the large number of inorganic fibers 42 contained in the sealing portion 4a as the resin partition portion 4 are arranged so that the longitudinal direction of each inorganic fiber 42 is three-dimensionally random. There is. Therefore, as shown in FIG. 5, it is assumed that the pressure in the hydrogen tank is reduced from the high pressure state, so that a bubble 61 and a crack 62 originating from the bubble 61 are generated in the sealing portion 4a. However, the expanded crack 62 is suppressed from further expansion by reaching the inorganic fiber 42 in the sealing portion 4a. Therefore, it is possible to prevent the generation of open cracks caused by the growth of cracks up to the surface of the sealing portion 4a. Note that FIG. 5 is a schematic cross-sectional view of the sealing portion 4a, and the outer frame portion 43 shown in FIG. 5 means the surface of the sealing portion 4a.

On the other hand, as shown in FIG. 6, unlike the present embodiment, a case where the longitudinal direction of each inorganic fiber 42 contained in the sealing portion 4a is oriented in one direction is considered. Note that FIG. 6 is a schematic cross-sectional view of the sealing portion 4a, and the outer frame portion 43 shown in FIG. 6 means the surface of the sealing portion 4a. In this case, when a bubble 61 and a crack 621 originating from the bubble 61 are generated in the sealing portion 4a due to the pressure in the hydrogen tank being reduced from the high pressure state, the crack 621 that has propagated is generated. Is easy to progress to pass between the inorganic fibers 42. Therefore, in this case, the crack 621 may extend to the surface of the sealing portion 4a and become an open crack 621. When the opening crack 621 occurs, hydrogen is introduced from the opening crack 621 to the vicinity of the temperature sensitive element 2, the temperature sensitive element 2 is reduced and deteriorated, and the temperature detection accuracy of the temperature sensor 1 may be lowered.

Therefore, as in the present embodiment, in a large number of inorganic fibers 42, by setting the longitudinal direction of each inorganic fiber 42 to a three-dimensionally random direction, cracks due to blister fracture occur in the sealing portion 4a. Even if it occurs, the growth of cracks is suppressed by the inorganic fiber 42, and it is possible to prevent the cracks from advancing to the surface of the sealing portion 4a.

The resin 41 constituting the sealing portion 4a is a polyamide-based resin or a polyphenylene sulfide resin. These materials are materials in which hydrogen in the hydrogen tank is difficult to dissolve even when the pressure in the hydrogen tank is in a high pressure state. Therefore, it is easy to reduce the amount of hydrogen dissolved in the resin 41 of the sealing portion 4a when the pressure in the hydrogen tank is reduced from the high pressure state. As a result, it is possible to suppress the generation of bubbles and cracks originating from the bubbles inside the resin 41 due to the vaporization of hydrogen in the sealing portion 4a due to the decompression in the hydrogen tank. As a result, the occurrence of open cracks can be suppressed.

The content of the inorganic fiber 42 in the sealing portion 4a is 10 wt% or more and 40 wt% or less. By increasing the content of the inorganic fiber 42 in the sealing portion 4a to 10 wt% or more in this way, even if bubbles and cracks due to blister destruction occur in the sealing portion 4a, the cracks are the inorganic fibers. It is easy to reach 42, and it is easy to prevent the crack from proceeding to the surface of the sealing portion 4a and becoming an open crack. The effect of setting the content of the inorganic fiber 42 in the sealing portion 4a to 10 wt% or more is supported by an experimental example described later. The content of the inorganic fiber 42 in the sealing portion 4a is 40 wt% or less. This makes it easy to improve the productivity of the sealing portion 4a. On the other hand, it has been confirmed that it is difficult to manufacture the inorganic fiber 42 having a content of more than 40 wt% in the sealing portion 4a.

The average length of the inorganic fiber 42 in the sealing portion 4a is 30 μm or more and 250 μm or less. By increasing the average length of the inorganic fiber 42 of the sealing portion 4a to 30 μm or more in this way, even if bubbles and cracks due to blister fracture occur in the sealing portion 4a, the crack is an inorganic fiber. It is easy to reach 42, and it is easy to prevent the crack from proceeding to the surface of the sealing portion 4a and becoming an open crack. The effect of setting the average length of the inorganic fiber 42 of the sealing portion 4a to 30 μm or more is supported by an experimental example described later. The average length of the inorganic fiber 42 of the sealing portion 4a is 250 μm or less. This makes it easy to improve the productivity of the sealing portion 4a. On the other hand, in the sealing portion 4a, it has been confirmed that it is difficult to manufacture the inorganic fiber 42 having an average length of more than 250 μm.

Further, when the angle formed between each inorganic fiber 42 and the virtual straight line L extending in an arbitrary direction is defined as the fiber angle θ in the arbitrary cross section of the sealing portion 4a, the fiber angle θ of each of the inorganic fibers 42 is defined as the fiber angle θ. The average is 10 ° or more. That is, the three-dimensional randomness of each inorganic fiber 42 in the sealing portion 4a in the longitudinal direction is high. As a result, even if bubbles and cracks due to blister fracture occur in the sealing portion 4a, the cracks easily reach the inorganic fiber 42, and the cracks proceed to the surface of the sealing portion 4a and open cracks. It is easy to suppress that.

As described above, according to the present embodiment, it is possible to provide a temperature sensor in which opening cracks are unlikely to occur in the sealing portion constituting the resin partition portion for separating the atmosphere in the hydrogen tank and the temperature sensitive element.

(Experimental Example 1)
In this example, it is quantitatively confirmed that the growth of cracks that may be formed in the resin due to the blister fracture can be suppressed by setting the longitudinal direction of each inorganic fiber in the resin to a three-dimensionally random direction. This is an experimental example.

In this example, two samples A1 and sample A2 were prepared. Sample A1 is a test piece containing a large number of unidirectionally oriented inorganic fibers in the resin. Sample A2 is a test piece containing inorganic fibers in which the longitudinal direction is three-dimensionally random.

Samples A1 and A2 are test pieces obtained by containing 30 wt% of glass fiber as an inorganic fiber in PA66 resin in a disk shape having a diameter of 20 mm and a thickness of 2 mm. The average length of the glass fibers contained in each of the sample A1 and the sample A2 was set to 200 μm.

Each sample was molded by injection molding. Then, in the adjustment of the inorganic fibers of each sample in the longitudinal direction, as described in the first embodiment, after injecting the mixed material constituting each sample into the mold, the time until the mixed material solidifies is adjusted. I went by doing.

Next, the test conditions of this example will be described. In this example, each sample is exposed to 85 MPa hydrogen for a whole day and night, and then the pressure is reduced from 85 MPa to atmospheric pressure at a decompression rate of 1 MPa / min, and then cracks in each sample are described. The travel distance was measured. The crack growth distance was measured using an X-ray CT scan. In this example, in both sample A1 and sample A2, cracks are generated in the sample starting from bubbles, and the crack growth distance is a linear distance from the void side end of the crack to the end opposite to the void. And said.
The results are shown in Table 1.

As can be seen from Table 1, the crack growth distance of sample A1 was 1.1 mm, and the crack growth distance of sample A2 was 2.2 mm. That is, in the PA66 resin, the longitudinal direction of each glass fiber is arranged so as to be three-dimensionally random in the PA66 resin, as compared with the sample A1 in which the longitudinal direction of each glass fiber is oriented in one direction. It can be seen that the prepared sample A2 can reduce the crack growth distance caused by the blister fracture.

As a result, in the temperature sensor arranged in the hydrogen tank shown in the first embodiment, the longitudinal direction of each inorganic fiber of the resin partition portion is three-dimensionally random, so that the crack caused by the blister fracture is caused. It can be seen that the progress of the resin can be suppressed and the occurrence of opening cracks in the resin partition can be suppressed.

(Experimental Example 2)
In this example, the resin contains inorganic fibers whose longitudinal directions are three-dimensionally random, and a plurality of test pieces in which the content of the inorganic fibers is variously changed, and the resin contains the inorganic fibers. This is an experimental example in which the crack growth distance was measured for a test piece that did not.

In this example, a sample B1 made of PA66 resin and not containing inorganic fibers and samples B2 to B5 in which glass fibers are contained as inorganic fibers in the PA66 resin and the glass fiber contents are different from each other are prepared. bottom. As shown in Table 2 below, the glass fiber contents of Samples B2 to B5 are 10 wt% for Sample B2, 20 wt% for Sample B3, 30 wt% for Sample B4, and 40 wt% for Sample B5. It was difficult in manufacturing to contain more than 40 wt% of glass fiber in the PA66 resin.

Each sample of Sample B1 to Sample B5 has a disk shape having a diameter of 20 mm and a thickness of 2 mm, as in Experimental Example 1. Further, in Samples B2 to B5, the average length of the glass fibers contained therein was set to 200 μm, as in Experimental Example 1.

Each sample was molded by injection molding. In each of the samples B2 to B5, as described in the first embodiment, by adjusting the time until the mixed material solidifies after injecting the mixed material constituting each sample into the mold. , The longitudinal direction of the inorganic fiber of each sample was set to a three-dimensionally random direction.

The test conditions and the means for measuring the crack growth distance in this example are the same as those in Experimental Example 1.
The results are shown in Table 2.

From Table 2, it can be seen that for sample B1 containing no glass fiber, the crack growth distance is relatively long at 1.3 mm, and cracks are likely to grow. On the other hand, it can be seen that the samples B2 to B5 containing 10 wt% or more and 40 wt% or less of glass fibers and having the longitudinal direction of each inorganic fiber randomly randomized can significantly suppress the crack growth distance. .. In particular, it can be seen that the crack growth distance can be further shortened by containing 20 wt% or more of glass fiber in the resin.

As a result, in the temperature sensor arranged in the hydrogen tank shown in the first embodiment, the longitudinal direction of each inorganic fiber in the resin partition is set to a three-dimensionally random direction, and the content of the inorganic fiber in the resin partition is set. It can be seen that by setting the content to 10 wt% or more and 40 wt% or less, the growth of cracks due to the fracture of the blister can be suppressed, and the occurrence of open cracks in the resin partition portion can be suppressed. Further, it can be seen that the growth of cracks can be further suppressed by setting the content of the inorganic fiber to 20 wt% or more in the resin partition portion.

(Experimental Example 3)
In this example, in a test piece containing inorganic fibers whose longitudinal directions are three-dimensionally random in the resin, crack growth occurs in a plurality of test pieces in which the average length of the inorganic fibers is variously changed. This is an experimental example of measuring the distance.

In this example, the PA66 resin contains glass fibers as inorganic fibers, and samples C1 to C4 having different average lengths of the glass fibers are prepared. As shown in Table 2 below, the average length of the glass fibers of Samples C1 to C4 is 10 μm for Sample C1, 30 μm for Sample C2, 100 μm for Sample C3, and 250 μm for Sample C4. It was difficult to prepare a test piece having an average length of glass fiber exceeding 250 μm. In this example as well, each sample has a three-dimensionally random direction in the longitudinal direction of the inorganic fiber of each sample by injection molding devised as described in the first embodiment. However, when an attempt was made to produce a glass fiber having an average length of more than 250 μm, it was difficult to make the average length of the glass fiber 250 μm or more because the glass fiber was broken during injection molding.

Similar to Experimental Example 1, each sample of Sample C1 to Sample C4 was prepared by containing 30 wt% of glass fiber as an inorganic fiber in PA66 resin and formed into a disk shape having a diameter of 20 mm and a thickness of 2 mm.

The test conditions and the means for measuring the crack growth distance in this example are the same as those in Experimental Example 1.
The results are shown in Table 3.

From Table 3, Samples C2 to C4, in which the average length of the glass fibers is 30 μm or more and 250 μm or less and the longitudinal direction of each inorganic fiber is three-dimensionally random, the crack growth distance is significantly suppressed. You can see that you can do it.

As a result, in the temperature sensor arranged in the hydrogen tank shown in the first embodiment, the longitudinal direction of each inorganic fiber in the resin partition is three-dimensionally random, and the average length of the inorganic fiber in the resin partition is set to a random direction. It can be seen that by setting the value to 30 μm or more and 250 μm or less, the growth of cracks caused by the fracture of the blister can be suppressed, and the occurrence of open cracks in the resin partition portion can be suppressed.

(Experimental Example 4)
This example is an experimental example in which the relationship between the average value of the fiber angles of the inorganic fibers contained in the resin and the crack growth distance is investigated.

In this example, seven samples D1 to D7 were prepared. Each sample is a test piece obtained by containing 30 wt% of glass fiber as an inorganic fiber in PA66 resin and forming it into a disk shape by injection molding.

The seven samples differ from each other in the average value of the fiber angles of the glass fibers. That is, the average value of the fiber angles of each sample is 0 ° for sample D1, 5 ° for sample D2, 10 ° for sample D3, 20 ° for sample D4, 30 ° for sample D5, 40 ° for sample D6, and sample D7. Is 50 °. That is, in the sample D1, the glass fiber is oriented in the injection direction at the time of injection molding.

Here, in this example, at the time of injection molding of each sample, a line parallel to the injection direction is set as a virtual straight line in a cross section parallel to the injection direction when the material constituting each sample is injected into the molding mold. The average of the fiber angles was calculated. The average of the fiber angles was the average of the fiber angles of 20 randomly selected inorganic fibers appearing in the cross section. The method for selecting the inorganic fiber here is the same as the method described in the first embodiment.

As for the adjustment of the average value of the fiber angles of each sample, as described in the first embodiment, after injecting the mixed material constituting each sample into the mold, the time until the mixed material solidifies is appropriately adjusted. I went by that.

Each sample has a disk shape with a diameter of 20 mm and a thickness of 2 mm, as in Experimental Example 1. Further, in each sample, the average length of the glass fiber contained in each sample was set to 200 μm as in Experimental Example 1.

The test conditions and the means for measuring the crack growth distance in this example are the same as those in Experimental Example 1.
The results are shown in Table 4. In Table 4, the average value of the fiber angles of each sample is described as the average fiber angle.

As can be seen from Table 4, the samples D2 to D7 having an average fiber angle of more than 0 ° are compared with the sample D1 having an average fiber angle of 0 ° (that is, the sample D1 in which the glass fiber is oriented in the injection direction). The crack growth distance is shortened. Therefore, it can be seen that the crack growth distance can be shortened by setting the average fiber angle to a value exceeding 0 °. Further, it can be seen that the crack growth distance can be further shortened by setting the average fiber angle to 10 ° or more. Further, it can be seen that the crack growth distance can be significantly shortened by setting the average fiber angle to 10 ° or more and 40 ° or less.

As a result, in the temperature sensor arranged in the hydrogen tank shown in the first embodiment, the average fiber angle of each inorganic fiber in the resin partition is set to 10 ° or more, so that crack growth due to blister fracture occurs. It can be seen that it is possible to suppress the occurrence of opening cracks in the resin partition portion. Furthermore, by setting the average fiber angle of each inorganic fiber in the resin partition to 10 ° or more and 40 ° or less, the growth of cracks due to blister fracture can be further suppressed, and opening cracks occur in the resin partition. It turns out that this can be suppressed.

(Embodiment 2)
As shown in FIG. 7, the present embodiment has the same basic structure as that of the first embodiment, but further includes an outer surrounding portion 4b that covers the sealing portion 4a of the first embodiment.

The outer surrounding portion 4b is formed so as to embed the sealing portion 4a inside. The outer surrounding portion 4b constitutes the resin partition portion 4. The outer surrounding portion 4b contains an inorganic fiber in the resin as in the sealing portion 4a of the first embodiment. As in the case of the sealing portion 4a of the first embodiment, the inorganic fibers of the outer surrounding portion 4b are arranged so that the longitudinal direction of each inorganic fiber is three-dimensionally random. The composition of the outer surrounding portion 4b is the same as that of the sealing portion 4a of the first embodiment.

In the present embodiment, the sealing portion 4a may be made of the same material as that of the first embodiment, or may be made of, for example, a resin containing no inorganic fiber.

Others are the same as those in the first embodiment.
In addition, among the codes used in the second and subsequent embodiments, the same codes as those used in the above-mentioned embodiments represent the same components and the like as those in the above-mentioned embodiments, unless otherwise specified.

In the present embodiment, in addition to the sealing portion 4a, an outer surrounding portion 4b is provided. The outer surrounding portion 4b contains a large number of inorganic fibers in the resin, and the inorganic fibers of the outer surrounding portion 4b are arranged so that the longitudinal direction of each inorganic fiber is three-dimensionally random. There is. Therefore, even if bubbles caused by blister fracture and cracks originating from the bubbles occur in the outer surrounding portion 4b, the propagated cracks reach the inorganic fibers in the outer surrounding portion 4b. This restrains further progress. Therefore, it is possible to prevent the outer surrounding portion 4b from generating an opening crack in which a crack extends to the surface of the outer surrounding portion 4b. Therefore, it is easy to prevent hydrogen in the hydrogen tank from reaching the inside of the outer surrounding portion 4b. Further, a sealing portion 4a is arranged inside the outer surrounding portion 4b, and a temperature sensitive element 2 is arranged further inside the sealing portion 4a. Therefore, it is easier to prevent hydrogen in the hydrogen tank from being introduced in the vicinity of the temperature sensitive element 2.
In addition, it has the same effect as that of the first embodiment.

( Reference form )
As shown in FIG. 8, this embodiment has the same basic structure as that of the second embodiment , but the configuration of the sealing portion 4a is changed.

In this embodiment , the sealing portion 4a is made of an insulating glass material. Specifically, the sealing portion 4a can be formed of, for example, borosilicate glass to which boron oxide is added. Even if the glass material is placed in a high-pressure hydrogen atmosphere such as in a hydrogen tank, hydrogen does not easily permeate. Therefore, by using the sealing portion 4a as a glass material, it is easy to prevent the blister from being broken in the sealing portion 4a.
Others are the same as in the second embodiment.

In this embodiment , by forming the sealing portion 4a with a glass material, it is easy to prevent hydrogen from penetrating into the sealing portion 4a. Further, as shown in the second embodiment, by covering the sealing portion 4a with the outer surrounding portion 4b where the opening crack is unlikely to occur, it is possible to further prevent hydrogen from being introduced in the vicinity of the temperature sensitive element 2. , Has the same effect as that of the second embodiment.

The present invention is not limited to each of the above embodiments, and can be applied to various embodiments without departing from the gist thereof. For example, the resin partition portion that separates the atmosphere in the hydrogen tank and the temperature-sensitive element, such as the cover and the housing shown in the first embodiment, is made of a resin and a large number of inorganic fibers, and the lengths of the respective lengths of the large number of inorganic fibers are formed. The direction may be a three-dimensionally random direction. When a plurality of members constitute a resin partition portion, at least one member constituting the resin partition portion is composed of a resin and a large number of inorganic fibers, and the longitudinal direction of each of the large number of inorganic fibers is three-dimensional. The direction may be random.

1 Temperature sensor 2 Temperature sensitive element 3 Element electrode wire 4 Resin partition 41 Resin 42 Inorganic fiber

Claims (5)

A temperature sensor (1) placed in a hydrogen tank.
A temperature-sensitive element (2) for detecting temperature,
A pair of element electrode wires (3) electrically connected to the temperature-sensitive element, and
A resin partition portion (4) for separating the atmosphere in the hydrogen tank and the temperature sensitive element is provided.
The resin partition portion has a sealing portion (4a) in which the temperature-sensitive element is directly embedded therein.
The sealing portion contains a large number of inorganic fibers (42) in the resin (41).
A large number of the inorganic fibers are arranged so that the longitudinal direction of each of the inorganic fibers is a three-dimensionally random direction. The temperature sensor according to claim 1, wherein the resin constituting the resin partition portion is a polyamide-based resin or a polyphenylene sulfide resin. The temperature sensor according to claim 1 or 2, wherein the content of the inorganic fiber in the resin partition portion is 10 wt% or more and 40 wt% or less. The temperature sensor according to any one of claims 1 to 3, wherein the average length of the inorganic fibers in the resin partition portion is 30 μm or more and 250 μm or less. When the angle of 90 ° or less formed between each inorganic fiber and the virtual straight line (L) extending in an arbitrary direction in the arbitrary cross section of the resin partition portion is defined as the fiber angle (θ), the inorganic fiber The temperature sensor according to any one of claims 1 to 4, wherein the average of each of the fiber angles is 10 ° or more.

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