Temperature measurement device

Abstract

This temperature measurement device (1) is used in an internal combustion engine which uses hydrogen gas as fuel. The temperature measurement device (1) includes a delivery pipe (2) and a temperature sensor (3). The delivery pipe (2) supplies fuel gas containing hydrogen gas to the fuel injection valve. The fuel injection valve injects and supplies the fuel gas to a combustion chamber of the internal combustion engine. The temperature sensor (3) is attached to the delivery pipe (2) and measures the temperature of the fuel gas. Furthermore, the temperature sensor (3) has a connection part (31) for connecting to the delivery pipe (2). In an annular space (11) formed between the connection part (31) and the delivery pipe (2), an annular elastic member (4) is disposed in a state compressed by the connection part (31) and the delivery pipe (2). The filling rate n of the annular elastic member (4) with respect to the annular space (11) is 95% or less.

Description

Temperature measuring device Cross-reference to related applications

[0001] This application is based on Japanese Application No. 2024-160551 filed on September 18, 2024, the contents of which are incorporated herein by reference.

[0002] This disclosure relates to a temperature measuring device.

[0003] For example, as disclosed in Patent Document 1, a temperature measuring device including a pipeline incorporating a medium and a temperature sensor attached to the pipeline for measuring the temperature of the medium is known. The temperature sensor described in Patent Document 1 has a housing connected to the pipeline. The temperature measuring device described in Patent Document 1 attempts to suppress leakage of the medium by disposing an annular elastic member between the housing and the pipeline.

[0004] Japanese Patent Application Laid-Open No. 10-115536

[0005] The temperature measuring device described in Patent Document 1 does not fully consider the relationship between the annular space formed between the housing and the pipeline and the annular elastic member disposed within this annular space. Therefore, particularly when the temperature sensor is used to measure the temperature of a gas containing hydrogen gas, depending on the relationship between the annular space and the annular elastic member, there is a risk of causing damage to the annular elastic member. That is, when attaching a temperature sensor to a pipeline or the like incorporating a gas containing hydrogen gas, depending on the relationship between the annular space and the annular elastic member, there is a risk of causing damage to the annular elastic member due to the expansion of the annular elastic member by hydrogen gas. Therefore, from the perspective of suppressing damage to the annular elastic member and achieving a longer service life, it can be said that there is room for further improvement.

[0006] This disclosure aims to provide a temperature measuring device capable of achieving a longer service life.

[0007] One aspect of the present disclosure is a temperature measuring device used in an internal combustion engine that uses hydrogen gas as fuel, comprising: a delivery pipe that supplies fuel gas containing hydrogen gas to a fuel injection valve that injects fuel gas containing hydrogen gas into the combustion chamber of the internal combustion engine; and a temperature sensor attached to the delivery pipe and used for measuring the temperature of the fuel gas, wherein the temperature sensor has a connecting portion that connects to the delivery pipe, and an annular elastic member is arranged in an annular space formed between the connecting portion and the delivery pipe in a state compressed by the connecting portion and the delivery pipe, and the filling rate n of the annular elastic member in the annular space is 95% or less, in the temperature measuring device.

[0008] In the above-described temperature measuring device, the filling ratio n of the annular elastic member in the annular space is 95% or less. Therefore, even if the annular elastic member expands due to hydrogen gas, it is possible to suppress the annular elastic member from protruding out of the annular space. As a result, damage to the annular elastic member can be suppressed, and its lifespan can be extended.

[0009] As described above, according to the above embodiment, a temperature measuring device that can achieve a longer lifespan can be provided. The symbols in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of this disclosure.

[0010] The above-mentioned objectives and other objectives, features and advantages of this disclosure will become clearer with reference to the attached drawings and the detailed description below. The drawings are as follows: Figure 1 is a diagram showing an internal combustion engine in Embodiment 1; Figure 2 is a cross-sectional view of the vicinity of the temperature sensor in Embodiment 1, along the mounting direction; Figure 3 is an enlarged cross-sectional view of the vicinity of the annular space in Embodiment 1, along the mounting direction; Figure 4 is a cross-sectional photograph of the annular elastic member after a hydrogen exposure test in Experimental Example 1; Figure 5 is a graph showing the relationship between elapsed time T and the amount of helium gas leakage when an endurance test was conducted at 150°C in Experimental Example 2; Figure 6 is a graph showing the relationship between the packing ratio n and the compressibility E in Experimental Example 3; Figure 7 is a graph showing the relationship between the wire diameter W of the annular elastic member and the compressibility E in Experimental Example 4; and Figure 8 is a graph showing the relationship between the wire diameter W of the annular elastic member and the packing ratio n in Experimental Example 4.

[0011] (Embodiment 1) An embodiment relating to a temperature measuring device will be described with reference to Figures 1 to 3. The temperature measuring device 1 of this embodiment is used in an internal combustion engine 10 that uses hydrogen gas as fuel. As shown in Figures 1 and 2, the temperature measuring device 1 comprises a delivery pipe 2 and a temperature sensor 3. The delivery pipe 2 supplies fuel gas containing hydrogen gas to a fuel injection valve 20. The fuel injection valve 20 injects and supplies fuel gas to the combustion chamber 101 of the internal combustion engine 10. The temperature sensor 3 is attached to the delivery pipe 2 and measures the temperature of the fuel gas. The temperature sensor 3 also has a connection part 31 that connects to the delivery pipe 2, as shown in Figure 2.

[0012] As shown in Figures 2 and 3, an annular elastic member 4 is placed in the annular space 11 formed between the connecting portion 31 and the delivery pipe 2, in a compressed state by the connecting portion 31 and the delivery pipe 2. The filling rate n of the annular elastic member 4 in the annular space 11 is 95% or less.

[0013] The temperature measuring device 1 of this embodiment can be used, for example, in an internal combustion engine 10 mounted on a vehicle, as a means of measuring the temperature of the fuel gas supplied to the combustion chamber 101. In this embodiment, the information on the fuel gas temperature measured by the temperature sensor 3 is transmitted to the ECU (electronic control unit). The ECU (not shown) controls the fuel injection valve 20 based on information such as the temperature of the fuel gas in the delivery pipe 2, and controls the amount of fuel gas supplied to the combustion chamber 101. In other words, by monitoring the temperature of the fuel gas in the delivery pipe 2 with the temperature sensor 3, the amount of fuel gas injected into the combustion chamber 101 can be controlled to be the optimal amount. In this specification, the longitudinal direction of the temperature sensor 3 is referred to as the sensor axis direction Z, and the central axis C of the temperature sensor 3 is referred to as the sensor central axis. In this specification, the radial direction of a circle centered on the sensor central axis C on a plane perpendicular to the sensor central axis C is referred to as the sensor radial direction. In addition, the direction in which the temperature sensor 3 is attached to the delivery pipe 2 is referred to as the attachment direction.

[0014] As shown in Figure 1, the internal combustion engine 10 includes a fuel tank 102 for storing high-pressure fuel gas and a fuel supply passage 103 for supplying fuel gas from the fuel tank 102 to the delivery pipe 2. The fuel supply passage 103 connects the fuel tank 102 and the delivery pipe 2 to each other. The internal combustion engine 10 also includes a plurality of combustion chambers 101. Each combustion chamber 101 is surrounded by a cylinder (not shown), a piston (not shown), and a cylinder head (not shown).

[0015] In this embodiment, the delivery pipe 2 is provided with multiple fuel injection valves 20 so as to be able to inject fuel gas into each of the multiple combustion chambers 101. The delivery pipe 2 temporarily stores the fuel gas to be supplied to the fuel injection valves 20.

[0016] In this embodiment, the internal pressure of the delivery pipe 2 can reach a high pressure of approximately 7 MPa. The internal pressure of the delivery pipe 2 can be, for example, 0 to 7 MPa. The hydrogen concentration in the fuel gas inside the delivery pipe 2 can be, for example, approximately 99.97%. In this embodiment, the temperature of the fuel gas inside the delivery pipe 2 is -40 to 120°C.

[0017] The temperature sensor 3 measures the temperature of the fuel gas stored in the inner space 23 of the delivery pipe 2 shown in Figure 2. The temperature sensor 3 is fastened and fixed to the delivery pipe 2. The temperature sensor 3 is attached to the delivery pipe 2 such that its central axis C is aligned with the mounting direction. In other words, in this embodiment, the sensor axis direction Z is also aligned with the mounting direction of the temperature sensor 3 relative to the delivery pipe 2.

[0018] The temperature sensor 3 has a main body 30 that measures the temperature of the fuel gas in the inner space 23. In this embodiment, the connecting portion 31 is fixed to the outer surface of the main body 30 by brazing. A temperature sensing portion 33 for detecting the temperature of the fuel gas is provided at one end of the main body 30 in the sensor axis direction Z, and a metal cover 32 is provided to cover the temperature sensing portion 33 from the outside. The portion of the main body 30 on the temperature sensing portion 33 side in the sensor axis direction Z protrudes from the connecting portion 31 into the inner space 23, and the temperature sensing portion 33 and the metal cover 32 are arranged in the inner space 23 of the delivery pipe 2. In this embodiment, the temperature sensing portion 33 is made of a thermistor element. The metal cover 32 can be made of a metal material such as stainless steel. In this specification, in the sensor axis direction Z, the side of the temperature sensing portion 33 relative to the connecting portion 31 is called the tip side Z1, and the opposite side is called the base end side Z2.

[0019] The connecting portion 31 has a fastening portion 311 and a compression portion 313. The fastening portion 311 is formed along the sensor axis direction Z and is fastened and fixed to the delivery pipe 2. The compression portion 313 is formed on the base end side Z2 of the fastening portion 311 and is located outside the delivery pipe 2. The compression portion 313 compresses the annular elastic member 4 in the mounting direction.

[0020] A threaded portion 312 is formed on a part of the outer circumferential surface of the fastening portion 311. The threaded portion 312 is fastened and fixed to the female threaded hole 22 of the delivery pipe 2 by screwing it in. In this embodiment, the nominal diameter of the threaded portion 312 is M10. The female threaded hole 22 is formed so as to connect the inner space 23 with the outside.

[0021] As shown in Figures 2 and 3, the fastening portion 311 has a cylindrical portion 314. The outer circumferential surface 316 of the cylindrical portion 314 does not have a threaded portion 312. The outer circumferential surface 316 of the cylindrical portion 314 is formed along the sensor axis direction Z. The cylindrical portion 314 is formed on the base end side Z2 of the threaded portion 312 and is formed between the threaded portion 312 and the compression portion 313 in the sensor axis direction Z.

[0022] The compression portion 313 is provided on the base end side Z2 of the fastening portion 311 and is formed to protrude outward in the sensor radial direction. In this embodiment, the tip surface 315 of the compression portion 313 is formed to be perpendicular to the sensor axis direction Z. Also in this embodiment, the compression portion 313 has a hexagonal shape when viewed from the mounting direction (not shown). When fixing the temperature sensor 3 to the delivery pipe 2, a hex wrench (not shown) is engaged with the compression portion 313 so as to cover the outer circumference of the compression portion 313, and the threaded portion 312 is fastened and fixed to the female threaded hole 22 by turning the hex wrench.

[0023] Furthermore, the delivery pipe 2 has an inclined surface 21, as shown in Figures 2 and 3. The inclined surface 21 faces the annular space 11 and is inclined with respect to the mounting direction of the temperature sensor 3 to the delivery pipe 2. The annular elastic member 4 is compressed in the mounting direction by the inclined surface 21 and the connecting portion 31. In addition, the inclined surface 21 is formed in an annular shape and is formed so that its diameter decreases as it approaches the tip side Z1. In other words, the inclined surface 21 is formed so that it approaches the sensor central axis C as it approaches the tip side Z1.

[0024] In this embodiment, the annular space 11 is surrounded by the tip surface 315 of the compression portion 313, the outer circumferential surface 316 of the cylindrical portion 314, and the inclined surface 21, as shown in Figure 3. The annular elastic member 4 is in pressure contact with the tip surface 315, the outer circumferential surface 316, and the inclined surface 21 around its entire circumference. In this embodiment, as shown in Figure 3, the temperature measuring device 1 is formed such that, in a cross-section including the sensor central axis C, the tip surface 315 facing the annular space 11 and the outer circumferential surface 316 facing the annular space 11 are orthogonal to each other. Considering the tolerances of the delivery pipe 2 and the connecting portion 31, as shown in Figure 2, the outer diameter D of the annular space 11 can be, for example, 13.9 to 14.0 mm, and the inner diameter d of the annular space 11 can be, for example, 8.95 to 9.00 mm.

[0025] Furthermore, the annular elastic member 4 seals the space between the connection portion 31 and the delivery pipe 2. The annular elastic member 4 is compressed in the sensor axis direction Z by the inclined surface 21 and the tip surface 315. In this embodiment, the annular elastic member 4, in its free state, has a circular cross-section perpendicular to its extension direction. The entire annular elastic member 4 is arranged within the annular space 11.

[0026] The annular elastic member 4 has rubber elasticity. The annular elastic member 4 can be made of, for example, ethylene propylene diene rubber or fluororubber. In this embodiment, the annular elastic member 4 is made of ethylene propylene diene rubber.

[0027] In this embodiment, the compressibility E of the annular elastic member 4 is 10% or more. Preferably, the compressibility E is 15% or more. Also, in this embodiment, the compressibility E is 30% or less. Preferably, the compressibility E is 24% or less.

[0028] The compressibility E is the ratio of the compression allowance σ (see Figure 3) of the annular elastic member 4 when the temperature sensor 3 is attached to the delivery pipe 2 to the wire diameter W (see Figure 3) of the annular elastic member 4 in its free state, and can be calculated using the following formula (1). The compression allowance σ is the distance the annular elastic member 4 is compressed when the temperature sensor 3 is attached to the delivery pipe 2. The wire diameter W of the annular elastic member 4 can be, for example, 1.85 mm ± 0.07 mm, taking tolerances into consideration. The compression allowance σ of the annular elastic member 4 can be, for example, 0.38 to 0.58 mm. In Figure 3, the annular elastic member 4 in its free state is shown by a dashed line. The wire diameter W is also the thickness of the annular elastic member 4, and the thickness of the annular elastic member 4 is also the diameter of the cross-section perpendicular to the extension direction of the annular elastic member 4. Compressibility E [%] = σ / W × 100 ... (1)

[0029] In this embodiment, the filling rate n is 78% or more. Preferably, the filling rate n is 82% or more. Also, preferably, the filling rate n is 90% or less.

[0030] The filling ratio n represents the ratio of the volume of the annular elastic member 4 placed within the annular space 11 to the volume of the annular space 11. In this embodiment, as shown in Figure 3, the annular space 11 is formed in the shape of an isosceles triangle in the cross-section including the sensor central axis C. In this embodiment, the width G of the annular space 11 in the sensor radial direction and the length L of the annular space 11 in the sensor axial direction Z are the same length. As described above, in the free state, the annular elastic member 4 has a circular cross-section perpendicular to its extension direction. Therefore, in this embodiment, the filling ratio n can be calculated using the following formula (2). Note that the width G is also the value of "(outer diameter D - inner diameter d) / 2". The width G can be, for example, 2.450 to 2.525 mm.

[0031]

[0032] Next, the effects of this embodiment will be explained. In the temperature measuring device 1 described above, the filling rate n is 95% or less. Therefore, even if the annular elastic member 4 expands due to hydrogen gas, it is possible to suppress the annular elastic member 4 from protruding out of the annular space 11. As a result, damage to the annular elastic member 4 can be suppressed, and its lifespan can be extended. Furthermore, it is preferable that the filling rate n is 90% or less. In this case, it is possible to further suppress the annular elastic member 4 from protruding out of the annular space 11.

[0033] Let's consider a temperature measuring device where the filling rate n is too high. In this case, if the annular elastic member expands due to hydrogen gas, the annular elastic member may not be able to fit within the annular space and may protrude outwards. This can cause so-called "protrusion failure," potentially damaging the annular elastic member. Therefore, the temperature measuring device 1 in this embodiment has a filling rate n of 95% or less. This prevents the annular elastic member 4 from protruding outwards from the annular space 11, even if it expands due to exposure to a high-temperature, high-pressure fuel gas environment. As a result, damage to the annular elastic member 4 is prevented, and its lifespan can be extended.

[0034] In this embodiment, the compressibility E of the annular elastic member 4 is 10% or more. Therefore, even when a temperature sensor 3 is installed in the delivery pipe 2 filled with high-pressure fuel gas, sufficient airtightness can be ensured by the annular elastic member 4. In other words, even if the annular elastic member 4 expands and contracts due to the influence of hydrogen gas, temperature, etc., the annular elastic member 4 can sufficiently ensure airtightness between the connection part 31 and the delivery pipe 2. Furthermore, it is preferable that the compressibility E is 15% or more. In this case, the airtightness of the annular elastic member 4 can be further improved.

[0035] In this embodiment, the compressibility ratio E is 30% or less. Therefore, damage to the annular elastic member 4 due to compression can be sufficiently suppressed. Specifically, in the temperature measuring device 1, the temperature sensor 3 is attached to the delivery pipe 2 with the annular elastic member 4 compressed in the mounting direction, thereby ensuring sealing against the high-pressure fuel gas inside the delivery pipe 2. However, if the compressibility ratio E is too high, there is a risk of damage such as so-called compression cracking in the annular elastic member 4. Therefore, in this embodiment, the compressibility ratio E is set to 30% or less. This makes it possible to ensure airtightness by the annular elastic member 4 while suppressing damage to the annular elastic member 4. In addition, by setting the compressibility ratio E to 30% or less, it is also possible to suppress the filling rate n from becoming too high, so that the annular elastic member 4 does not protrude out of the annular space 11. Furthermore, it is preferable that the compressibility ratio E is 24% or less. In this case, it is possible to ensure airtightness by the annular elastic member 4 while further suppressing damage to the annular elastic member 4.

[0036] In this embodiment, the filling rate n is 78% or higher. Therefore, damage due to movement of the annular elastic member 4 can be sufficiently suppressed. In other words, if the filling rate n is too low, the annular elastic member 4 may move within the annular space 11 due to expansion and contraction of the annular elastic member 4 caused by the pressure of hydrogen gas or fuel gas, etc. And, along with the movement of the annular elastic member 4, there is a risk of damage to the annular elastic member 4. Therefore, in this embodiment, the filling rate n is set to 78% or higher. As a result, movement of the annular elastic member 4 within the annular space 11 can be sufficiently suppressed, and damage to the annular elastic member 4 can be sufficiently suppressed. In addition, by setting the filling rate n to 78% or higher, it is possible to prevent the compressibility E from becoming too low, so that sufficient airtightness by the annular elastic member 4 can be ensured. Furthermore, it is preferable that the filling rate n is 82% or higher. In this case, movement of the annular elastic member 4 within the annular space 11 can be further suppressed.

[0037] The annular elastic member 4 is made of ethylene propylene diene rubber. Therefore, swelling due to hydrogen gas and deterioration of the annular elastic member 4 due to high temperatures are more easily suppressed. As a result, damage to the annular elastic member 4 and a decrease in sealing performance can be further suppressed. In addition, the annular elastic member 4 tends to have excellent chemical resistance, etc. Therefore, its lifespan can be further extended.

[0038] The annular elastic member 4 is compressed in the mounting direction by the inclined surface 21 and the connecting portion 31. Therefore, the annular elastic member 4 can more effectively seal the space between the temperature sensor 3 and the delivery pipe 2, and the annular elastic member 4 is less likely to be damaged when the temperature sensor 3 is attached to the delivery pipe 2. In other words, when the temperature sensor 3 is attached to the delivery pipe 2, the annular elastic member 4 is compressed by the inclined surface 21, which does not have corners, etc., and the connecting portion 31, making the annular elastic member 4 less likely to be damaged. As a result, the airtightness provided by the annular elastic member 4 can be further improved, and its lifespan can be extended.

[0039] Furthermore, the inclined surface 21 can be formed, for example, by cutting or performing other operations on the base end of the female screw hole 22. Therefore, the annular space 11 can be easily provided, improving manufacturability.

[0040] In this embodiment, the temperature sensor 3 is fixed to the delivery pipe 2 by the fastening portion 311, and is also fastened and fixed to the delivery pipe 2 by engaging a hex wrench with the compression portion 313 and turning it. Therefore, the temperature sensor 3 can be fixed to the delivery pipe 2 without using separate components such as flanges. As a result, miniaturization and simplification can be achieved.

[0041] As described above, this embodiment provides a temperature measuring device 1 that can achieve a longer lifespan.

[0042] (Experimental Example 1) In this example, while the basic structure was the same as that of the temperature measurement device of Embodiment 1, a hydrogen gas exposure test was conducted in a high-temperature environment of 150°C using a plurality of temperature measurement devices with different filling ratios n. Specifically, a temperature measurement device with a temperature sensor attached to a delivery pipe was placed in a furnace at 150°C while being exposed to hydrogen gas, taken out of the furnace after 480 hours, and the presence or absence of extrusion damage to the annular elastic member was confirmed. Also, the hydrogen gas exposure test in this example was conducted with the annular elastic member exposed to hydrogen gas. Further, in this example, as shown in FIG. 4, two samples (Samples A and B) with a filling ratio n of 90%, two samples (Samples C and D) with a filling ratio n of 95%, and two samples (Samples E and F) with a filling ratio n of 97% were used for the test. In this example, the material of the annular elastic member was ethylene propylene diene rubber. Note that the photographs of Samples A to F in FIG. 4 are photographs of cross-sections perpendicular to the extending direction of the annular elastic member, respectively.

[0043] As shown in FIG. 4, in Samples A to D with a filling ratio n of 90% or 95%, no damage due to extrusion from the annular space was confirmed in the annular elastic member. On the other hand, in Samples E and F with a filling ratio n of 97%, as shown by the arrow P in FIG. 4, damage due to extrusion from the annular space was confirmed. From this result, it is considered that by setting the filling ratio n to 95% or less, even when the annular elastic member is in a state of being exposed to a high-temperature environment and hydrogen gas, the extrusion failure of the annular elastic member can be sufficiently suppressed. Therefore, it can be said that the temperature measurement device of Embodiment 1 with a filling ratio n of 95% or less can sufficiently suppress the annular elastic member from protruding from the annular space even if the annular elastic member expands due to hydrogen gas. Therefore, it can be said that the temperature measurement device of Embodiment 1 can sufficiently suppress damage to the annular elastic member.

[0044] (Experimental Example 2) In this example, as shown in the graph in Figure 5, while the basic structure was the same as that of the temperature measuring device in Embodiment 1, a durability test was conducted in a high-temperature environment of 150°C using multiple temperature measuring devices with different compressibility ratios E. Specifically, a temperature measuring device with a temperature sensor attached to a delivery pipe was placed in a 150°C furnace, removed from the furnace after a predetermined time, and its airtightness was evaluated. In order to evaluate the airtightness, the temperature measuring device was immediately placed in a cold storage unit after being removed from the high-temperature furnace and left in a low-temperature environment of -28°C for 2 hours. After that, the airtightness between the connection and the delivery pipe was immediately evaluated. Specifically, helium gas was filled into the inner space of the delivery pipe until the internal pressure reached 10 MPa, and then the amount of helium gas leakage was measured to evaluate the airtightness.

[0045] In this example, the 150°C durability test was conducted using four samples each with compressibility E of 8%, 10%, 20%, and 30%, as shown in Figure 5. In this example, a helium gas leak rate of 0.08 ml / min or less was defined as the criterion for sufficient airtightness, and the compressibility E that satisfies this criterion was determined.

[0046] In the graph of FIG. 5, the horizontal axis represents the elapsed time T from the start of the test, and the vertical axis represents the leakage amount of helium gas. As shown in the graph of FIG. 5, the samples with a compression ratio E of 10 to 30% resulted in meeting the above criteria for all elapsed times T during which the leakage amount was measured. On the other hand, although the sample with a compression ratio E of 8% met the above criteria up to an elapsed time T of 240 hours, when the elapsed time T was 480 hours or more, all the samples did not meet the above criteria. From these results, it is considered that the temperature measuring device can sufficiently provide durability with respect to airtightness by setting the compression ratio E to 10% or more. That is, it can be said that the temperature measuring device of Embodiment 1 with a compression ratio E of 10% or more can sufficiently ensure the airtightness between the connection part and the delivery pipe by the annular elastic member even if the annular elastic member expands and contracts due to the influence of hydrogen gas or the like. Also, by setting the compression ratio E to 15% or more, it is considered that the airtightness by the annular elastic member can be more sufficiently ensured. Further, from the graph of FIG. 5, by setting the compression ratio E to 20% or more, the airtightness can be further improved, and furthermore, by setting the compression ratio E to 30% or more, it is considered that the airtightness can be further improved.

[0047] (Experimental Example 3) In this example, as shown in FIG. 6, while the basic structure was the same as that of Embodiment 1, the relationship between the filling ratio n and the compression ratio E was determined using a plurality of temperature measuring devices with different filling ratios n and compression ratios E. In the graph of FIG. 6, the circles plot the experimental results of each temperature measuring device. Also, an approximate straight line for these plots is shown in the graph of FIG. 6.

[0048] From the plot of the graph in Figure 6, it can be seen that when the filling rate n is 95%, the compressibility E is 30%, and when the compressibility E is 10%, the filling rate n is 78%. Furthermore, from the approximation line of the graph in Figure 6, it can be seen that when the compressibility E is 15%, the filling rate n is 82%, and when the filling rate n is 90%, the compressibility E is 24%. From these results and the results of experimental examples 1 and 2, it can be said that by setting the compressibility E to 10-30% or the filling rate n to 78-95%, it is possible to sufficiently ensure airtightness by the annular elastic member while sufficiently suppressing damage to the annular elastic member. It is also presumed that by setting the compressibility E to 15-24% or the filling rate n to 82-90%, it is possible to further improve airtightness by the annular elastic member while further suppressing damage to the annular elastic member. Therefore, the temperature measuring device of Embodiment 1, in which the filling rate n is 95% or less and the compressibility E is 10% or more, can be said to be able to sufficiently ensure airtightness by the annular elastic member while sufficiently suppressing damage to the annular elastic member.

[0049] (Experimental Example 4) In this example, as shown in the graphs in Figures 7 and 8, the basic structure was the same as that of the temperature measuring device in Embodiment 1, and the relationship between the wire diameter W and the compressibility E, and the relationship between the wire diameter W and the packing ratio n were analyzed while changing the wire diameter W of the annular elastic member. In this example, analyses were performed for both the case where the width G of the annular space was relatively small at 2.45 mm and the case where the width G was relatively large at 2.525 mm. Furthermore, the wire diameter W was analyzed in the range of 1.78 to 1.92 mm.

[0050] As shown in the graph in Figure 7, when the width G is 2.45 mm and the wire diameter W of the annular elastic member is 1.92 mm, the compressibility E is 30%. Furthermore, in both the cases where the width G is 2.45 mm and 2.525 mm, when the wire diameter W is between 1.78 and 1.92 mm, the compressibility E falls within the range of 10 to 30%. From these results and the results of experimental examples 1 to 3, it is presumed that when the width G is between 2.450 and 2.525 mm, setting the wire diameter W to 1.78 to 1.92 mm can suppress damage to the annular elastic member while ensuring sufficient airtightness.

[0051] Furthermore, as shown in the graph in Figure 8, when the width G is 2.45 mm and the wire diameter W is 1.92 mm, the filling rate n is 95%. Also, when the width G is 2.525 mm and the wire diameter W is 1.78 mm, the filling rate n is 78%. From these results and the results of experimental examples 1 to 3, it is inferred that when the width G is 2.450 to 2.525 mm, setting the wire diameter W to 1.78 to 1.92 mm will sufficiently suppress damage to the annular elastic member while ensuring sufficient airtightness by the annular elastic member.

[0052] In the above embodiment 1, the annular elastic member 4 has a circular cross-section perpendicular to its extension direction in its free state. However, the annular elastic member may also have an elliptical or polygonal cross-section perpendicular to its extension direction in its free state.

[0053] In the above embodiment 1, the inclined surface 21 is formed in a straight line in a cross-section including the sensor central axis C. However, the inclined surface can also be, for example, a concave surface recessed toward the tip side or a convex surface protruding toward the base end side in a cross-section including the sensor central axis.

[0054] In the above embodiment 1, the annular space 11 is formed to be triangular in cross-section including the sensor central axis C. However, the annular space can also be a space that is rectangular or the like in cross-section including the sensor central axis.

[0055] Furthermore, the fuel injector can, for example, directly inject fuel gas into the combustion chamber. Alternatively, the fuel injector can, for example, inject fuel gas into the intake port, thereby supplying fuel gas to the combustion chamber via the intake port.

[0056] Furthermore, the annular space can be, for example, a space completely enclosed by the connection part and the delivery pipe. Alternatively, the annular space can be, for example, a space that communicates with the outside space. In this case, for example, the volume of the space enclosed by the extended surface of the inclined surface forming the annular space and the extended surface of the connection part forming the annular space can be considered the volume of the annular space.

[0057] This disclosure is not limited to the embodiments described above, and can be applied to various embodiments without departing from its essence.

[0058] This disclosure is described in accordance with embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also encompasses various variations and variations within the equivalence range. In addition, various combinations and forms, as well as other combinations and forms that include one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

[0059] <Other> The features of this disclosure are as follows: [Item 1] A temperature measuring device (1) used in an internal combustion engine (10) that uses hydrogen gas as fuel, comprising: a delivery pipe (2) that supplies fuel gas to a fuel injection valve (20) that injects fuel gas containing hydrogen gas into a combustion chamber (101) of the internal combustion engine; and a temperature sensor (3) attached to the delivery pipe and used for measuring the temperature of the fuel gas, wherein the temperature sensor has a connection portion (31) that connects to the delivery pipe, and an annular elastic member (4) is arranged in an annular space (11) formed between the connection portion and the delivery pipe in a compressed state by the connection portion and the delivery pipe, and the filling rate n of the annular elastic member in the annular space is 95% or less, a temperature measuring device. [Item 2] The temperature measuring device according to Item 1, wherein the compressibility E of the annular elastic member is 10% or more. [Item 3] The temperature measuring device according to item 1 or 2, wherein the compressibility E of the annular elastic member is 30% or less. [Item 4] The temperature measuring device according to any one of items 1 to 3, wherein the filling rate n is 78% or more. [Item 5] The temperature measuring device according to any one of items 1 to 4, wherein the annular elastic member is made of ethylene propylene diene rubber. [Item 6] The temperature measuring device according to any one of items 1 to 5, wherein the delivery pipe faces the annular space and has an inclined surface (21) that is inclined with respect to the mounting direction of the temperature sensor to the delivery pipe, and the annular elastic member is compressed in the mounting direction by the inclined surface and the connection part. [Item 7] The temperature measuring device according to any one of items 1 to 6, wherein the filling rate n is 90% or less. [Item 8] The temperature measuring device according to item 2, wherein the compressibility E is 15% or more. [Item 9] The temperature measuring device according to item 3, wherein the compressibility E is 24% or less. [Item 10] The temperature measuring device according to item 4, wherein the filling rate n is 82% or more.

Claims

1. A temperature measuring device (1) used in an internal combustion engine (10) that uses hydrogen gas as fuel, comprising: a delivery pipe (2) that supplies fuel gas to a fuel injection valve (20) that injects fuel gas containing hydrogen gas into a combustion chamber (101) of the internal combustion engine; and a temperature sensor (3) attached to the delivery pipe and used to measure the temperature of the fuel gas, wherein the temperature sensor has a connecting portion (31) that connects to the delivery pipe, and an annular elastic member (4) is arranged in an annular space (11) formed between the connecting portion and the delivery pipe in a compressed state by the connecting portion and the delivery pipe, and the filling rate n of the annular elastic member in the annular space is 95% or less.

2. The temperature measuring device according to claim 1, wherein the compressibility E of the annular elastic member is 10% or more.

3. The temperature measuring device according to claim 1 or 2, wherein the compressibility E of the annular elastic member is 30% or less.

4. The temperature measuring device according to claim 1 or 2, wherein the filling rate n is 78% or more.

5. The temperature measuring device according to claim 1 or 2, wherein the annular elastic member is made of ethylene propylene diene rubber.

6. The temperature measuring device according to claim 1 or 2, wherein the delivery pipe faces the annular space and has an inclined surface (21) that is inclined with respect to the mounting direction of the temperature sensor to the delivery pipe, and the annular elastic member is compressed in the mounting direction by the inclined surface and the connecting portion.

7. The temperature measuring device according to claim 1 or 2, wherein the filling rate n is 90% or less.

8. The temperature measuring device according to claim 2, wherein the compressibility E is 15% or more.

9. The temperature measuring device according to claim 3, wherein the compressibility E is 24% or less.

10. The temperature measuring device according to claim 4, wherein the filling rate n is 82% or more.

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