Temperature sensor

Abstract

The temperature sensor (1) is configured for use in a hydrogen tank. The temperature sensor (1) comprises a temperature sensing element (2), a pair of element electrode wires (3), a pair of conductive components (4) and a housing (5). The temperature sensing element (2) detects the temperature in the hydrogen tank. The pair of element electrode wires (3) are electrically connected to the temperature sensing element (2). The pair of conductive components (4) are electrically connected to different element electrode wires (3). The housing (5) is made of resin, i.e., made of a material containing resin. The housing (5) has a pair of through holes (51) through which the pair of conductive components (4) are respectively inserted and held. A gap (c) is formed between at least one of the pair of conductive components (4) and the inner peripheral surface of the through hole (51) of the housing (5).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on Japanese application No. 2019-186124 filed on October 9, 2019, the contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to temperature sensors. Background Art

[0004] The temperature sensor described in Patent Document 1 includes a temperature-sensing element, an element electrode wire made of a precious metal such as platinum and electrically connected to the temperature-sensing element, a conductive member electrically connected to the element electrode wire, and a resin housing that holds these components. By making the housing from resin, the temperature sensor can be made lighter and less expensive.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-133317 Summary of the Invention

[0008] Temperature sensors are also used, for example, within the hydrogen tanks of fuel cell vehicles to detect the temperature within the tanks. Based on the temperature sensor's detection of the hydrogen tank's temperature, the filling rate of the hydrogen tank is controlled. However, the temperature sensor described in Patent Document 1 presents the following issues when used within the hydrogen tanks.

[0009] When hydrogen is filled into a hydrogen tank, the pressure inside the hydrogen tank increases. As the pressure inside the hydrogen tank rises, the amount of hydrogen dissolved in the resin housing of the temperature sensor disposed in the hydrogen tank increases.

[0010] Here, as the hydrogen in the hydrogen tank is used for the driving of the fuel cell vehicle, the hydrogen in the hydrogen tank decreases and the pressure in the hydrogen tank is reduced. As the pressure is reduced, a pressure difference is generated between the inside and outside of the shell, and the hydrogen dissolved in the shell will detach from the shell surface to the outside of the shell. However, when the hydrogen tank is in a high-pressure state, especially when the hydrogen is immersed in a position far from the shell surface (for example, near a pair of conductive parts), it cannot completely detach from the shell when the hydrogen tank is decompressed, but expands inside the shell, which may cause bubbles or cracks starting from the bubbles in the shell. This phenomenon is called bubble destruction.

[0011] Cracks in the housing caused by bubble collapse are also thought to form from the housing surface and connect to both conductive components. This would reduce the electrical insulation between the conductive components. Furthermore, moisture could enter the hydrogen tank as an impurity and enter the cracks, potentially causing an electrical short circuit between the conductive components.

[0012] The present disclosure intends to provide a temperature sensor capable of suppressing bubble destruction in a housing.

[0013] One embodiment of the present disclosure is a temperature sensor disposed in a hydrogen tank, comprising:

[0014] Temperature sensing element, used to detect temperature;

[0015] a pair of element electrode wires electrically connected to the temperature sensing element;

[0016] a pair of conductive members electrically connected to different element electrode lines; and

[0017] The resin housing has a pair of through holes for inserting the pair of conductive members respectively therethrough to hold the pair of conductive members;

[0018] A gap is formed between at least one of the conductive members and the inner peripheral surface of the through hole.

[0019] In the temperature sensor of the above-described method, a gap is formed between the conductive component of at least one side and the inner peripheral surface of the through hole of the shell. Therefore, as the hydrogen tank is decompressed, when the hydrogen tank equipped with the temperature sensor is in a high-pressure state, the hydrogen dissolved in the shell will pass through the shell and detach from the shell surface to the outside of the shell. In addition, the hydrogen will also pass through the shell and detach from the gap. In the shell, hydrogen collides with the polymer chains of the resin while moving between the polymer chains, and in the gap, it can move more quickly because there is no substance that hinders the movement. Therefore, when the hydrogen tank is in a high-pressure state, the hydrogen dissolved in the shell is more likely to detach from the inside of the shell when the pressure in the hydrogen tank is reduced. In this way, bubble damage in the shell can be prevented.

[0020] As described above, according to the above aspect, it is possible to provide a temperature sensor capable of suppressing the occurrence of bubble destruction in the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above-mentioned and other objects, features and advantages of the present disclosure will become more apparent through the following detailed description with reference to the accompanying drawings.

[0022] Figure 1 is a partial main sectional view of the temperature sensor in embodiment 1;

[0023] Figure 2 yes Figure 1 Sectional view along line II-II;

[0024] Figure 3 is a schematic cross-sectional view of a microscopic observation of the surface of the conductive member and the surface of the housing in Embodiment 1;

[0025] Figure 4 This is a cross-sectional view showing the distance between hydrogen immersed in the central portion of the shell and the outside of the shell in Embodiment 1;

[0026] Figure 5 This is a cross-sectional view showing the distance between hydrogen immersed in the central portion of the shell and the outside of the shell in a comparative embodiment;

[0027] Figure 6 This is a cross-sectional view showing the appearance of bubble destruction in the shell in the comparative method;

[0028] Figure 7 is a cross-sectional view of the temperature sensor in Embodiment 2;

[0029] Figure 8 is a cross-sectional view of a temperature sensor in a modified form of embodiment 2;

[0030] Figure 9 is a cross-sectional view of a temperature sensor in another variation of embodiment 2;

[0031] Figure 10 is a partial main sectional view of the sample A1 in Experimental Example 1;

[0032] Figure 11 is a partial main sectional view of the sample A3 in Experimental Example 1;

[0033] Figure 12 is a partial front cross-sectional view of a temperature sensor in yet another embodiment (one);

[0034] Figure 13 is a cross-sectional view perpendicular to the longitudinal direction of the temperature sensor in yet another embodiment (Part 2);

[0035] Figure 14 In the embodiment, (a) is a partial main cross-sectional view of the temperature sensor in another embodiment (third), (b) is a partial main cross-sectional view of the temperature sensor in the embodiment Figure 14 (a) is the BB cross-sectional view, (c) is the Figure 14 (a) CC cross-sectional view. DETAILED DESCRIPTION

[0036] (Implementation Method 1)

[0037] use Figures 1 to 6An embodiment of the temperature sensor will be described.

[0038] The temperature sensor 1 of this embodiment is disposed in a hydrogen tank for use.

[0039] like Figure 1 As shown, the temperature sensor 1 includes a temperature sensing element 2, a pair of element electrode wires 3, a pair of conductive components 4, and a shell 5. The temperature sensing element 2 detects the temperature inside the hydrogen tank. The pair of element electrode wires 3 are electrically connected to the temperature sensing element 2. A pair of conductive components 4 are electrically connected to different element electrode wires 3. The shell 5 is made of resin, that is, made of a material containing resin. The shell 5 has a pair of through holes 51 for respectively inserting a pair of conductive components 4 to hold the pair of conductive components 4. Figure 1 、 Figure 2 As shown, a gap c is formed between each of the pair of conductive members 4 and the inner peripheral surface of the through hole 51 of the housing 5. In the drawings, the gap c is drawn larger for convenience.

[0040] Below, this method is described in detail.

[0041] Hereinafter, the direction in which the central axis of the temperature sensor 1 extends is referred to as the X-direction. Furthermore, one side in the X-direction, where the pair of element electrode wires 3 are connected to the temperature sensing element 2, is referred to as the distal end, and the opposite side is referred to as the proximal end. Furthermore, the direction perpendicular to the X-direction, where the pair of conductive members 4 are arranged side by side, is referred to as the Y-direction.

[0042] The temperature sensor 1 of this embodiment is installed in a hydrogen tank used in, for example, a fuel cell vehicle (FCV). The hydrogen filling rate is controlled based on the temperature sensor 1's detection of the tank's internal temperature. Since hydrogen filling generates shock within the tank, the temperature sensor 1 is designed to be robust enough to withstand this shock.

[0043] In addition, the hydrogen tank becomes under high pressure when it is filled with hydrogen. When the hydrogen tank is in a high-pressure state, the hydrogen in the hydrogen tank dissolves in the shell 5 of the temperature sensor 1. As the hydrogen in the hydrogen tank is used for the driving of the fuel cell vehicle, the hydrogen in the hydrogen tank decreases and the pressure in the hydrogen tank decreases. As the pressure is reduced, the hydrogen dissolved in the shell 5 will pass through the shell 5 and flow out to the outside of the shell 5. At this time, a part of the hydrogen dissolved in the shell 5 cannot escape from the shell 5, but expands inside the shell 5. It is generally believed that bubbles and cracks starting from this bubble may be generated inside the shell 5. The temperature sensor 1 of this method is designed to suppress the occurrence of such cracks.

[0044] The temperature sensing element 2 of the temperature sensor 1 is composed of, for example, a thermistor. However, the present invention is not limited thereto and the temperature sensing element 2 may also be composed of a thermocouple or a temperature measuring resistor made of, for example, platinum. The temperature sensing element 2 is fixed by being clamped by the distal ends of a pair of element electrode wires 3.

[0045] like Figure 1 As shown, a pair of element electrode wires 3 are arranged in parallel along the Y direction. The pair of element electrode wires 3 are formed of, for example, a platinum alloy in a linear shape. The distal ends of the pair of element electrode wires 3 and the temperature sensing element 2 are sealed inside a sealing body 6 .

[0046] like Figure 1 As shown, the sealing body 6 isolates the temperature sensing element 2 from the hydrogen atmosphere in the hydrogen tank. The sealing body 6 is made of, for example, an insulating glass material. However, this is not limiting; the sealing body 6 may also be made of a resin, such as the same resin as the housing 5 described later. The base ends of the pair of element electrode wires 3 are connected to the tip ends of different conductive members 4.

[0047] like Figure 1 As shown in FIG. 1 , a pair of conductive members 4 are arranged substantially parallel to each other. The conductive members 4 are formed straight along the X direction. Figure 2 As shown in FIG. 1 , the conductive component 4 is formed in a quadrilateral shape in a cross section perpendicular to the X direction. In addition, the conductive component 4 is not limited thereto, and can be in various shapes such as a round rod shape with a circular cross section, a polygonal prism shape with a polygonal cross section, etc. The conductive component 4 can be made of a conductive material such as SUS304. Figure 1 、 Figure 2 As shown, the conductive component 4 is held by the housing 5 .

[0048] like Figure 1 As shown, the housing 5 is formed long in the X direction. The housing 5 is made of a resin containing a polyamide resin such as PA66 resin or a polyphenylene sulfide resin (ie, PPS resin). The housing 5 is, for example, a portion mounted on a hydrogen tank.

[0049] like Figure 1 As shown, the housing 5 has a pair of through-holes 51 extending in the X direction. The through-holes 51 are formed to be elongated in the X direction. Different conductive members 4 are disposed in each of the pair of through-holes 51. The conductive members 4 are disposed in the through-holes 51 such that their distal ends and proximal ends protrude from the through-holes 51.

[0050] like Figure 1 、 Figure 2As shown, a gap c is formed between the conductive component 4 and the inner circumferential surface of the through-hole 51. A gap c is formed continuously between each of the pair of conductive components 4 and the inner circumferential surface of the through-hole 51 in which the conductive component 4 is located, extending over a length greater than half the total length of the through-hole 51 in the X direction. Furthermore, a gap c is formed continuously from at least one end of the through-hole 51 between at least one of the conductive components 4 and the inner circumferential surface of the through-hole 51 of the housing 5 in which the conductive component 4 is located. In this embodiment, the pair of gaps c formed between each of the pair of conductive components 4 and the inner circumferential surface of the through-hole 51 are formed continuously from one end of the through-hole 51 to the other end in the X direction. In other words, the gaps c are open on both sides in the X direction.

[0051] like Figure 2 As shown, gap c is formed over the entire circumference of conductive member 4. Gap c has a portion where the dimension w in the direction perpendicular to the surface of conductive member 4 is 100 nm or larger. In other words, a portion or the entire gap c has a dimension w in the direction normal to the surface of conductive member 4 facing the portion that is 100 nm or larger.

[0052] like Figure 3 As schematically shown, the surface roughness Rz of the conductive member 4 located within the through-hole 51 of the housing 5, i.e., the surface of the in-hole conductive portion 41, is 30 μm or less. Specifically, the surface roughness of at least the portion of the conductive member 4 facing the inner circumference of the through-hole 51 of the housing 5 is 30 μm or less.

[0053] like Figure 3 As shown, microscopic concave-convex portions 42 are formed on the surface of the conductive component 4. The surface of a metal component is generally not formed into a completely planar shape, and there are concave-convex portions when observed microscopically. Furthermore, in this embodiment, the housing 5 is formed by insert molding in which the conductive component 4 is arranged in a mold. Therefore, a portion of the housing 5 enters the concave-convex portions 42 of the conductive component 4 and is molded into a shape consistent with the concave-convex portions 42. As a result, the inner peripheral surface of the through hole 51 of the housing 5 engages with the concave-convex portions 42 on the surface of the conductive component 4, so that the conductive component 4 does not fall off from the housing 5.

[0054] Next, an example of a method for manufacturing the housing 5 in this embodiment will be described. The gap c between the inner peripheral surface of the through hole 51 of the housing 5 and the conductive member 4 can be formed by, for example, designing the method for manufacturing the housing 5 .

[0055] The shell 5 is formed by insert molding, which is a process of arranging a pair of conductive components 4 at predetermined intervals in a plurality of molds for molding the shell 5, and injecting the resin constituting the shell 5 into the molds. In this method, in insert molding, first, the temperature of each mold is heated to a temperature higher than normal temperature. Then, the resin constituting the shell 5 is filled into the mold in which the conductive component 4 is arranged and the pressure is maintained, and thereafter, only the mold in contact with the conductive component 4 is actively cooled. In this way, the conductive component 4 can be actively cooled and greatly shrunk before the resin constituting the shell 5 solidifies and shrinks. As a result, a gap c is formed between the conductive component 4 and the shell 5. By designing the insert molding in this way, a gap c can be actively formed between the conductive component 4 and the inner peripheral surface of the through hole 51 of the shell 5.

[0056] Next, an example of a method of confirming the presence or absence of the gap c between the inner peripheral surface of the through-hole 51 of the housing 5 and the conductive member 4 from the finished product of the temperature sensor 1 will be described.

[0057] For example, the presence of the gap c can be detected by a leak test using He (helium), which has an atomic radius second only to that of hydrogen. In the leak test, a molded body consisting of a housing 5 and a conductive component 4 without a gap c is first prepared. He is introduced into the molded body from one side in the X direction between the housing 5 and the conductive component 4. The amount of He leaking from the other side in the X direction between the housing 5 and the conductive component 4 of the molded body is then measured, i.e., the reference leakage amount.

[0058] Next, He is introduced between the housing 5 and the conductive member 4 of the temperature sensor 1, which is the target of the gap c detection, in the same manner as in the molded article, and the leakage rate is detected. If the leakage rate exceeds a reference leakage rate by a predetermined value or more, it can be determined that a gap c has formed between the housing 5 and the conductive member 4.

[0059] Alternatively, as another method, the gap c may be directly observed using a transmission electron microscope (TEM) or a cross section may be directly observed using a scanning electron microscope (SEM).

[0060] Next, the effects of this method will be described.

[0061] In the temperature sensor 1 of this embodiment, a gap c is formed between the conductive component 4 on at least one side and the inner peripheral surface of the through hole 51 of the shell 5. Therefore, as the pressure in the hydrogen tank is reduced, when the hydrogen tank in which the temperature sensor 1 is installed is in a high-pressure state, the hydrogen dissolved in the shell 5 passes through the shell 5 and escapes from the surface of the shell 5 to the outside of the shell 5. In addition, the hydrogen also passes through the shell 5 and escapes into the gap c. In the shell 5, hydrogen moves between the polymer chains while colliding with the polymer chains of the resin, and in the gap c, it can move more quickly because there is no substance that hinders the movement. Therefore, the hydrogen dissolved in the shell 5 when the hydrogen tank is in a high-pressure state is more likely to escape from the inside of the shell 5 when the pressure in the hydrogen tank is reduced. In this way, bubble damage in the shell 5 can be prevented.

[0062] Here, for example Figure 5 As shown in FIG. 1 , consider a temperature sensor 9 that does not have a gap as in the present embodiment. In this temperature sensor 9, when hydrogen H exists near the center of the shell 5, when the hydrogen tank is depressurized, the hydrogen moves in the shell 5 over a relatively long distance, which is approximately the radius r of the shell 5, and is eventually released to the outside of the shell 5. In addition, when hydrogen H moves inside the shell 5, the polymer chains of the resin become an obstacle, so the time it takes to move is relatively long. Therefore, when the hydrogen tank is depressurized, the hydrogen in the shell 5 cannot be completely released from the shell 5, but expands inside the shell 5, and as a result, Figure 6 As shown, there is a concern that bubbles may be generated in the housing 5 and cause damage.

[0063] Next, if Figure 4 As shown, consider the case where a gap c is formed between the inner circumference of the through-hole 51 of the housing 5 and the conductive member 4, as in this embodiment. In this case, if hydrogen H is present near the center of the housing 5, when the hydrogen tank is depressurized, the hydrogen H is released to the outside of the housing 5 (here, the gap c) by moving over the short distance d to the gap c. Furthermore, when the hydrogen H moves within the gap c, there are no obstacles to hinder the movement of the hydrogen H, and the time required for movement is short. Therefore, when the hydrogen tank is depressurized, the hydrogen H in the housing 5 is easily released from the housing 5, which can suppress the occurrence of bubble destruction.

[0064] Here, generally speaking, when insert molding is performed on the resin housing 5 that holds the conductive component 4, in order to ensure the airtightness of the conductive component 4 and the housing 5, the insert molding is performed in a manner that eliminates the gap between them. For example, the gap between the metal component and the resin material is eliminated by performing a coupling treatment on the surface of the metal component, or as disclosed in Japanese Patent Publication No. 2018-126960, the gap between the metal component and the resin component is eliminated by forming embossing or other concave-convex shapes on the surface of the metal component. On the other hand, this method is the opposite. As mentioned above, in order to prevent bubble destruction of the housing 5 and the resulting reduction in electrical reliability, a gap c is deliberately formed between the housing 5 and the conductive component 4.

[0065] Furthermore, a gap c is formed continuously between at least one of the conductive members 4 and the inner circumferential surface of the through-hole 51 of the housing 5 in which the conductive member 4 is disposed, extending over a length greater than half the total length of the through-hole 51 in the longitudinal direction of the through-hole 51. By forming the gap c continuously longer than the specified length, hydrogen dissolved in the housing 5 is easily released into the gap c, i.e., to the exterior of the housing 5, when the hydrogen tank is depressurized. Consequently, the occurrence of bubble collapse can be further suppressed.

[0066] Furthermore, a gap c is defined between at least one of the conductive members 4 and the inner circumferential surface of the through-hole 51 of the housing 5 in which the conductive member 4 is disposed, extending continuously from at least one end of the through-hole 51. Therefore, when the hydrogen tank is depressurized, hydrogen released from the housing 5 into the gap c is released from the edge of the gap c to the outside of the temperature sensor 1. This prevents a pressure difference from occurring between the gap c between the inner circumferential surface of the through-hole 51 of the housing 5 and the conductive member 4, and the space within the hydrogen tank.

[0067] The gap c has a portion with a size of 100 nm or more in a direction perpendicular to the surface of the conductive member 4. The diameter of a hydrogen molecule is approximately 0.3 nm, and by forming a gap c sufficiently large relative to this diameter, hydrogen can easily move in the gap c.

[0068] The surface roughness Rz of the portion of the conductive member 4 disposed in the housing 5 is 30 μm or less. This prevents the surface of the conductive member 4 and the housing 5 from coming into close contact with each other, and prevents a gap c from being formed therebetween.

[0069] Furthermore, the housing 5 contains polyamide resin or polyphenylene sulfide resin. These materials are less likely to dissolve the hydrogen in the hydrogen tank even when the pressure inside the hydrogen tank reaches a high level. This reduces the amount of hydrogen that initially enters the housing 5, thereby preventing the occurrence of bubble damage.

[0070] As described above, according to this aspect, it is possible to provide a temperature sensor capable of suppressing the occurrence of bubble destruction in the housing.

[0071] (Implementation Method 2)

[0072] like Figure 7 As shown, this embodiment is an embodiment in which the shape of the conductive member 4 is changed compared to the first embodiment.

[0073] In this embodiment, the central portion 411 of the in-hole conductive portion 41 of each conductive member 4 is formed so that the width in the Y direction is narrower than that of the adjacent in-hole conductive portion 41 in the X direction. Figure 7 As shown, the shape of the surface 410 of the conductive part 41 in the hole on the cross section parallel to the X direction (hereinafter sometimes referred to as simply the parallel cross section) has a curved shape. In this embodiment, the shape of the surface 410 of the conductive part 41 in the hole on the parallel cross section parallel to both the X direction and the Y direction has a curved shape. That is, the shape of the surface 410 of the conductive part 41 in the hole of each conductive component 4 on the parallel cross section is not a straight line, but has a curved shape such as a bend or a curve. The curved shape here does not include microscopic bumps such as scratches formed on the surface of the conductive component 4, but indicates curvature when observed macroscopically. In addition, there are countless cross sections parallel to the X direction, and it is sufficient as long as the surface 410 of the conductive part 41 in the hole is formed in a curved shape on at least one of the cross sections.

[0074] Furthermore, in this embodiment, the housing 5 is also formed by insert molding similar to that of Embodiment 1. Accordingly, the housing 5 is formed along the surface 410 of the in-hole conductive portion 41 of the conductive member 4. As a result, the shape of the inner peripheral surface 510 of the through-hole 51 in a parallel cross-section has a shape that curves along the surface 410 of the in-hole conductive portion 41.

[0075] The rest is the same as in the first embodiment.

[0076] In addition, among the reference numerals used in the present embodiment, the same reference numerals as those used in the existing embodiment indicate the same components as those in the existing embodiment unless otherwise specified.

[0077] In this embodiment, the surface 410 of the in-hole conductive portion 41 has a curved shape in a parallel cross-section. Furthermore, the inner circumferential surface 510 of the through-hole 51 of the housing 5 has a curved shape in a parallel cross-section along the surface 410 of the in-hole conductive portion 41. Therefore, the in-hole conductive portion 41 of the conductive component 4 engages with the housing 5, easily preventing the conductive component 4 from falling out of the housing 5.

[0078] The other effects are the same as those of the first embodiment.

[0079] In addition, in this method, it is also possible to use, for example, Figure 8The shape is as shown in the example. Figure 8 The structure shown is: in a parallel cross-section, among the surfaces 410 of the conductive part 41 in each hole, only the surface 410 on the side farther away from the other conductive part 41 in the hole in the Y direction has a curved shape, and the inner peripheral surface 511 of the through hole 51 of the shell 5 has a shape curved along the surface 410 of the conductive part 41 in the hole.

[0080] In addition, in this method, it is also possible to use, for example, Figure 9 The structure is as shown in the example. Figure 9 The illustrated structure is an example of a structure in which the conductive portion 41 is formed into a crank shape, thereby curving the surface 410 of the conductive portion 41 in a parallel cross-section. In this embodiment, the central portion 411 of each conductive portion 41 is formed into a crank shape, facing the opposite side of the other conductive portion 41 in the Y direction. Furthermore, the inner peripheral surface 511 of the through-hole 51 of the housing 5 has a curved shape that follows the surface 410 of the conductive portion 41.

[0081] In addition, although not shown in the figure, for example, the conductive portion 41 in the hole may have a portion protruding or recessed in directions perpendicular to both the X direction and the Y direction, and the inner peripheral surface 511 of the through hole 51 of the shell 5 may have a shape curved along the surface 410 of the conductive portion 41 in the hole.

[0082] (Implementation 3)

[0083] This embodiment has the same basic structure as that of the first embodiment, but the material of the housing 5 is changed.

[0084] In this embodiment, the housing 5 is formed by a resin containing a large amount of inorganic fibers. The inorganic fiber content in the housing 5 is 10% to 40% by weight. In this embodiment, the housing 5 can be made of, for example, a polyamide resin such as PA66 resin containing 33% by weight of glass fiber as the inorganic fiber. Furthermore, the average length of the large amount of inorganic fibers in the housing 5 is 30 μm to 250 μm.

[0085] The rest is the same as in the first embodiment.

[0086] Next, the effects of this method will be described.

[0087] In this embodiment, the content of inorganic fibers in the shell 5 is greater than 10 wt% and less than 40 wt%. In this way, by making the content of inorganic fibers in the shell 5 as high as 10 wt% or more, even if bubbles and cracks are generated in the shell 5 due to bubble destruction, the cracks are likely to reach the inorganic fibers, and it is easy to suppress the cracks from developing to the surface of the shell 5 and becoming open cracks. In addition, the effect of setting the content of inorganic fibers in the shell 5 to greater than 10 wt% can be supported by the experimental examples described later. In addition, the content of inorganic fibers in the shell 5 is less than 40 wt%. As a result, the productivity of the shell 5 can be easily improved. On the other hand, it was confirmed that manufacturing is more difficult when the content of inorganic fibers in the shell 5 exceeds 40 wt%.

[0088] In addition, the average length of the inorganic fibers in the shell 5 is greater than 30 μm and less than 250 μm. In this way, by making the average length of the inorganic fibers in the shell 5 longer than 30 μm, even if bubbles and cracks are generated in the shell 5 due to bubble destruction, the cracks will easily reach the inorganic fibers, and the cracks will be difficult to develop larger. In addition, the effect of setting the average length of the inorganic fibers in the shell 5 to more than 30 μm can be supported by the experimental examples described later. In addition, the average length of the inorganic fibers in the shell 5 is less than 250 μm. Thus, it is easy to improve the productivity of the shell 5. On the other hand, it was confirmed that manufacturing is more difficult when the average length of the inorganic fibers in the shell 5 exceeds 250 μm.

[0089] The other effects are the same as those of the first embodiment.

[0090] (Experimental Example 1)

[0091] This example evaluates the likelihood of bubble collapse in a temperature sensor by varying the ratio of the length of the gap between the inner circumferential surface of the through hole of the housing and the conductive member in the X direction relative to the total length of the through hole of the housing in the X direction.

[0092] In this example, if Figure 10 、 Figure 11 As an example, four samples A1 to A4 were prepared. In each sample A1 to A4, a pair of linear metal pieces 40, representing the conductive member 4, were placed through a cylindrical body 50, representing a housing 5. In this example, the longitudinal direction of the metal pieces 40 is referred to as the X-direction, and the direction perpendicular to the X-direction and the direction in which the pair of metal pieces 40 are arranged is referred to as the Y-direction. Furthermore, in this example, the portion of the metal piece 40 located inside the cylindrical body 50 is referred to as the in-hole conductive portion 41.

[0093] The four samples A1 to A4 varied the ratio L2 / L1 (hereinafter referred to as the gap formation ratio) of the length L2 of the gap c in the X direction between the metal member 40 and the cylindrical body 50 relative to the length L1 of the conductive portion 41 in the X direction. The gap formation ratio for sample A1 was 40%, for sample A2 it was 50%, for sample A3 it was 80%, and for sample A4 it was 100%. The length of the gap c in the X direction ("Gap Length" in Table 1) and the length of the conductive portion 41 in the X direction ("Conductive Portion Length in Table 1") for each of samples A1 to A4 are shown in Table 1 below. Figure 10 An example of sample A1 is shown in FIG. Figure 11 An example of sample A3 is shown in . In samples A1 to A3, the gap c is open on one side in the X direction, and in sample A4, the gap c is open on both sides in the X direction.

[0094] In this example, Sample A4 can be produced using the same insert molding method as in Embodiment 1. For Samples A1 to A3, molds appropriately divided along the X-direction are used, and each mold temperature is first raised above room temperature. Then, the mold containing the metal component 40 is filled with the resin forming the cylindrical body 50 and pressure maintained. Afterwards, only the mold on one side in the X-direction, in contact with the metal component 40, is actively cooled. This allows the gap c to be formed at the desired location.

[0095] The dimensions of the cylindrical body 50 of each of Samples A1-A4 are: a length in the X direction (equal to L1 in this example) of 20 mm and a diameter φ of 6 mm. Similar to the housing 5 in Embodiment 3, the cylindrical body 50 of each of Samples A1-A4 is formed by adding a large amount of inorganic fibers to the resin. Each of Samples A1-A4 is made by adding 30 wt% of glass fibers to PA66. Furthermore, the average length of the glass fibers in each of Samples A1-A4 is 200 μm.

[0096] The metal member 40 of each sample A1 to A4 was made of SUS304. Furthermore, the thickness (i.e., the dimension perpendicular to both the X and Y directions) of the metal member 40 of each sample A1 to A4 was set to 0.6 mm, the width L3 in the Y direction was set to 1.5 mm, and the length L4 in the X direction was set to 30 mm. Furthermore, the surface roughness Rz of the metal member 40 was 16 μm.

[0097] In this example, each sample A1-A4 was exposed to 85 MPa hydrogen for one day and one night. The hydrogen atmosphere was then depressurized from 85 MPa to atmospheric pressure at a rate of 1 MPa / min. This process was repeated until the cylinder 50 of each sample A1-A4 had been inspected for cracks. The temperature of each sample A1-A4 before depressurization was 85°C, and the temperature drop with depressurization occurred naturally. The presence of cracks in each sample A1-A4 was confirmed using an X-ray CT scanner.

[0098] Furthermore, the ease of occurrence of bubble destruction in each sample A1 to A4 after the test was evaluated. The evaluations were A, B, and C, which will be described later. That is, if no cracks due to bubble destruction are observed on the cylinder 50 even after the hydrogen tank is repeatedly depressurized to a number that is equivalent to the case where the hydrogen tank has been used for 20 years, the evaluation is A. If no cracks due to bubble destruction are observed on the cylinder 50 even after the hydrogen tank is repeatedly depressurized to a number that is equivalent to the case where the hydrogen tank has been used for 15 years, but cracks due to bubble destruction are observed on the cylinder 50 when the hydrogen tank is repeatedly depressurized to a number that is equivalent to the case where the hydrogen tank has been used for 20 years, the evaluation is B. If cracks due to bubble destruction are observed on the cylinder 50 when the hydrogen tank is repeatedly depressurized to a number that is equivalent to the case where the hydrogen tank has been used for 15 years, the evaluation is C. The results are shown in Table 1, which will be described later.

[0099] [Table 1]

[0100]

[0101] Table 1 shows that Sample A1, with a gap formation rate of 40%, received an evaluation of C. On the other hand, Samples A2 to A4, with gap formation rates of 50% or higher, received evaluations of A or B, indicating that bubble damage is less likely to occur. This indicates that setting the gap formation rate to 50% or higher reduces the likelihood of bubble damage. Furthermore, Sample A4, with a gap formation rate of 100%, received an evaluation of A. Therefore, it can be seen that in the temperature sensor 1 placed in the hydrogen tank, forming the gap c so that both sides of the through-hole 51 of the housing 5 are open in the X direction further prevents bubble damage.

[0102] (Experimental Example 2)

[0103] This example is an example of evaluating the difficulty of occurrence of bubble destruction when the surface roughness Rz of the conductive member in the temperature sensor is variously changed.

[0104] In this example, four samples B1 to B4 were prepared. Similar to Experimental Example 1, each sample B1 to B4 had a pair of linear metal pieces 40, assumed to be conductive components, placed through a cylindrical body 50, assumed to be a housing. As in Experimental Example 1, in this example, the longitudinal direction of the metal pieces 40 is referred to as the X-direction, the direction perpendicular to the X-direction and the direction in which the pair of metal pieces 40 are arranged is referred to as the Y-direction, and the portion of the metal piece 40 placed inside the cylindrical body 50 is referred to as the in-hole conductive portion 41.

[0105] The four samples B1 to B4 had different surface roughness Rz of the conductive portion 41 within the hole of the metal member 40. The surface roughness Rz of the conductive portion 41 within the hole of the sample B1 was 10 μm, the surface roughness Rz of the conductive portion 41 within the hole of the sample B2 was 16 μm, the surface roughness Rz of the conductive portion 41 within the hole of the sample B3 was 30 μm, and the surface roughness Rz of the conductive portion 41 within the hole of the sample B4 was 40 μm.

[0106] The materials and dimensions of the cylindrical body 50 and the metal member 40 of the other samples B1 to B4 are the same as those of Experimental Example 1. The cylindrical body 50 of each sample is manufactured by insert molding in the same manner as in the first embodiment.

[0107] In this example, similar to Experimental Example 1, each sample B1-B4 was exposed to 85 MPa hydrogen for one day and one night. The hydrogen atmosphere was then depressurized from 85 MPa to atmospheric pressure at a rate of 1 MPa / min. This process was repeated until the hydrogen tank had been used for 15 years, and the presence of cracks in the cylindrical body 50 of each sample B1-B4 was confirmed. The temperature of each sample B1-B4 before depressurization was 85°C, and the temperature drop with depressurization occurred naturally. The presence of cracks in each sample B1-B4 was confirmed using an X-ray CT scanner.

[0108] The ease of bubble collapse in each of the samples B1 to B4 after the test was evaluated. These were evaluated as B and C, described below. If no cracks due to bubble collapse were observed in the cylindrical body 50 even after the hydrogen tank was repeatedly depressurized to a number equivalent to a 15-year hydrogen tank life, the evaluation was B. If cracks due to bubble collapse were observed in the cylindrical body 50 after the hydrogen tank was repeatedly depressurized to a number equivalent to a 15-year hydrogen tank life, the evaluation was C. The results are shown in Table 2, described below.

[0109] [Table 2]

[0110]

[0111] As can be seen from Table 2, samples B1 to B3 whose surface roughness Rz of the conductive part 41 in the hole is less than 30 μm are evaluated as B, which means that bubble damage is difficult to occur. In other words, by setting the surface roughness Rz of the conductive part 41 in the hole to less than 30 μm, bubble damage is difficult to occur. From this, it can be seen that in the temperature sensor arranged in the hydrogen tank, by setting the surface roughness Rz of the conductive part in the hole of the conductive component arranged in the through hole of the shell to less than 30 μm, it is easy to suppress the occurrence of bubble damage. On the other hand, it can be seen that sample B4 whose surface roughness Rz of the conductive part 41 in the hole exceeds 30 μm is evaluated as C. This is believed to be because if the surface roughness Rz of the conductive part 41 in the hole is greater than 30 μm, the cylinder 50 enters the surface unevenness of the conductive part 41 in the hole, the close contact between the cylinder 50 and the metal part 40 is improved, and it is difficult to form a gap c between the cylinder 50 and the metal part 40. On the other hand, as mentioned above, by setting the surface roughness Rz of the conductive portion in the hole of the conductive component arranged in the through hole of the shell in the temperature sensor arranged in the hydrogen tank to less than 30 μm, it is easy to form a gap between the conductive portion in the hole of the conductive component and the inner peripheral surface of the through hole of the shell, resulting in the easy suppression of the occurrence of bubble destruction.

[0112] (Experimental Example 3)

[0113] This example is an example of evaluating the difficulty of occurrence of bubble destruction when the content rate of inorganic fibers in the casing of the temperature sensor is variously changed.

[0114] In this example, five samples C1 to C5 were prepared. Similar to Experimental Examples 1 and 2, each sample C1 to C5 had a pair of linear metal pieces 40, assumed to be conductive components, placed through a cylindrical body 50, assumed to be a housing. As in Experimental Examples 1 and 2, in this example, the longitudinal direction of the metal pieces 40 is referred to as the X-direction, the direction perpendicular to the X-direction and the direction in which the pair of metal pieces 40 are arranged is referred to as the Y-direction, and the portion of the metal piece 40 placed inside the cylindrical body 50 is referred to as the in-hole conductive portion 41.

[0115] In this example, cylinder 50 of sample C1 is made of a material made of PA66 resin and containing no inorganic fibers. Cylindrical body 50 of sample C2 is made of a material containing 10 wt% of glass fibers as inorganic fibers in PA66 resin. Cylindrical body 50 of sample C3 is made of a material containing 20 wt% of glass fibers as inorganic fibers in PA66 resin. Cylindrical body 50 of sample C4 is made of a material containing 30 wt% of glass fibers as inorganic fibers in PA66 resin. Cylindrical body 50 of sample C5 is made of a material containing 40 wt% of glass fibers as inorganic fibers in PA66 resin. However, manufacturing a PA66 resin containing more than 40 wt% of glass fibers is difficult.

[0116] In each of the samples C1 to C5, the average length of the glass fibers in the cylinder 50 was 200 μm, similar to Experimental Examples 1 and 2. The other dimensions of the cylinder 50 and the material and dimensions of the metal member 40 of each of the samples C1 to C5 were the same as those of Experimental Example 1.

[0117] The test conditions and the evaluation method for the ease of occurrence of bubble collapse in this example were the same as those in Experimental Example 2. The results are shown in Table 3.

[0118] [Table 3]

[0119]

[0120] As shown in Table 3, Sample C1, which contained no glass fiber in the cylinder 50, received an evaluation of C, indicating that bubble failure easily occurred. On the other hand, Samples C2 to C5, which contained glass fiber in a range of 10 wt% to 40 wt% in the cylinder 50, all received an evaluation of B, indicating that bubble failure was less likely to occur.

[0121] This shows that, in a temperature sensor disposed in a hydrogen tank, by setting the content of inorganic fibers in the casing to 10 wt % or more and 40 wt % or less, the occurrence of cracks due to bubble collapse can be suppressed.

[0122] (Experimental Example 4)

[0123] This example is an example of evaluating the difficulty of occurrence of bubble destruction when the average length of the inorganic fibers in the casing of the temperature sensor is variously changed.

[0124] In this example, five samples D1 to D4 were prepared. Similar to Experimental Examples 1 to 3, each sample D1 to D4 had a pair of linear metal pieces 40, assumed to be conductive components, placed through a cylindrical body 50, assumed to be a housing. As in Experimental Examples 1 to 3, in this example, the longitudinal direction of the metal pieces 40 is referred to as the X-direction, the direction perpendicular to the X-direction and the direction in which the pair of metal pieces 40 are arranged is referred to as the Y-direction, and the portion of the metal piece 40 placed inside the cylindrical body 50 is referred to as the in-hole conductive portion 41.

[0125] In this example, samples D1 to D4 were prepared, each containing 30 wt% of glass fiber as an inorganic fiber in PA66 resin, with varying average glass fiber lengths. The average glass fiber length in cylinder 50 of sample D1 was 10 μm, the average glass fiber length in cylinder 50 of sample D2 was 30 μm, the average glass fiber length in cylinder 50 of sample D3 was 100 μm, and the average glass fiber length in cylinder 50 of sample D4 was 250 μm. However, increasing the average glass fiber length in cylinder 50 to more than 250 μm is difficult from a manufacturing perspective.

[0126] In each of the samples D1 to D4, the cylinder 50 contains 30 wt% of glass fiber in PA66 resin. The other dimensions of the cylinder 50 and the material and dimensions of the metal member 40 of each of the samples D1 to D4 are the same as those of Experimental Example 1.

[0127] The test conditions and the evaluation method for the ease of occurrence of bubble collapse in this example were the same as those in Experimental Example 2. The results are shown in Table 4.

[0128] [Table 4]

[0129]

[0130] As can be seen from Table 4, samples D2 to D4 having an average glass fiber length of 30 μm or more and 250 μm or less were evaluated as B, indicating that bubble destruction was less likely to occur.

[0131] This shows that, in the temperature sensor disposed in the hydrogen tank, by setting the average length of the inorganic fibers in the casing to 30 μm or more and 250 μm or less, the development of cracks due to bubble collapse can be suppressed.

[0132] The present disclosure is not limited to the above-described embodiments, but can be applied to various embodiments without departing from the spirit and scope of the present disclosure.

[0133] For example, Figure 12 As shown, the gap c may also be closed at both ends in the X direction.

[0134] In addition, in each of the above embodiments, an example in which the gap c is formed over the entire circumference of the conductive member 4 is shown, but if Figure 13 As shown, the gap c may also be formed only in a portion of the circumferential direction. In this case, as Figure 14 As shown, the gap c may also be formed so that the circumferential position varies according to the position in the X direction and is continuously formed from one end to the other end of the through hole 51 of the housing 5 in the X direction. Figure 14 In (a), the gap is omitted.

[0135] While the present disclosure has been described with reference to exemplary embodiments, it should be understood that the present disclosure is not limited to these embodiments and configurations. Various modifications and equivalents are encompassed by the present disclosure. Furthermore, various combinations and configurations, including combinations and configurations that include only one element, more elements, or fewer elements, also fall within the scope and spirit of the present disclosure.

Claims

1. A temperature sensor, disposed in a hydrogen tank, characterized in that: have: Temperature sensing element, used to detect temperature; a pair of element electrode wires electrically connected to the temperature sensing element; a pair of conductive members electrically connected to different electrode lines of the element; as well as The resin housing has a pair of through holes for inserting the pair of conductive members respectively therethrough to hold the pair of conductive members; A gap is formed between at least one of the conductive members and the inner peripheral surface of the through hole. The surface of the conductive portion in the through hole of the conductive component arranged in the through hole of the shell has a curved shape in a cross-section parallel to the length direction of the conductive component, and the shape of the inner circumferential surface of the through hole of the shell in the cross-section has a curved shape along the surface of the conductive portion in the hole.

2. The temperature sensor according to claim 1, characterized in that The gap is continuously formed over a length not less than half of the entire length of the through hole in the longitudinal direction of the through hole between at least one of the conductive members and the inner peripheral surface of the through hole of the housing in which the conductive member is disposed.

3. The temperature sensor according to claim 1 or 2, characterized in that: The gap is formed continuously from at least one end of the through-hole between at least one of the conductive members and the inner peripheral surface of the through-hole of the housing in which the conductive member is arranged.

4. The temperature sensor according to claim 1 or 2, characterized in that: The gap has a portion having a size of 100 nm or more in a direction perpendicular to the surface of the conductive member.

5. The temperature sensor according to claim 1 or 2, characterized in that: The surface roughness Rz of a portion of the conductive member disposed in the through-hole is 30 μm or less.

6. The temperature sensor according to claim 1 or 2, characterized in that: The shell contains polyamide resin or polyphenylene sulfide resin.

7. The temperature sensor according to claim 1 or 2, characterized in that: The shell is formed by containing a large amount of inorganic fibers in a resin, and the content of the inorganic fibers in the shell is 10 wt % or more and 40 wt % or less.

8. The temperature sensor according to claim 1 or 2, characterized in that: The shell includes a resin containing a large amount of inorganic fibers, and the average length of the inorganic fibers in the shell is 30 μm or more and 250 μm or less.

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