JP2011021972A - Pressure measurement device and vehicle including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely correct a pressure value output from a pressure sensor when measuring the pressure of hydrogen by a pressure sensor having a metal member in which a deep hole is formed. <P>SOLUTION: A pressure measurement device 100 includes a hydrogen storage part 12 storing hydrogen to be supplied to a hydrogen consuming device and a pressure sensor 60 including the metal member 62 having the hole part 72 which has one end opened and the other end having a bottom and to which at least a part of the hydrogen supplied from the hydrogen storage part is introduced, a pressure detection element 78 provided at a position of the outer surface of the metal member 62 facing the bottom surface of the hole part 72, and an output part outputting an electric signal obtained by the pressure detection element 78, as a pressure value indicating the pressure of the hydrogen. The pressure measurement device 100 further includes a correction part 130 correcting the pressure value when the pressure value output from the pressure sensor 60 is equal to or higher than a prescribed value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for measuring the pressure of hydrogen.

  As a pressure sensor for detecting the pressure of a high-pressure gas, for example, there is a pressure sensor disclosed in Patent Document 1. The pressure sensor described in Patent Document 1 has a structure in which a deep hole is formed in a metal member made of a low thermal expansion metal such as 42 alloy. In this pressure sensor, the pressure of the gas is measured by introducing a high-pressure gas to be measured into the above-described hole and detecting the deformation of the bottom of the hole with a strain gauge. The pressure sensor described in Patent Document 1 uses a metal member having such a structure to increase the pressure resistance against high-pressure gas.

  However, when such a pressure sensor is used to measure the pressure of high-pressure hydrogen gas, a phenomenon that hydrogen permeates through the metal member may occur. In particular, if the permeated hydrogen stays between the metal member and the strain gauge, there is a problem that the output of the strain gauge fluctuates due to the pressure of the staying hydrogen, resulting in an error in the output value from the pressure sensor.

JP 2001-296198 A

  Considering such problems, the problem to be solved by the present invention is to accurately determine the pressure value output from the pressure sensor when the pressure of hydrogen is measured by a pressure sensor having a metal member in which a deep hole is formed. There is to correct it.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1] A pressure measuring device for measuring the pressure of hydrogen, which is a hydrogen storage portion for storing hydrogen to be supplied to the hydrogen consuming device, and a hole portion having one end opened and a bottom at the other end. A metal member provided with a hole into which at least a part of hydrogen supplied from the reservoir is introduced, a pressure detection element provided at a position of the outer surface of the metal member facing the bottom surface of the hole, and An output unit that outputs an electrical signal obtained by the pressure detection element as a pressure value indicating the hydrogen pressure; and when the pressure value output from the pressure sensor is equal to or greater than a predetermined value, A pressure measurement device comprising a correction unit that corrects a pressure value.

  With such a pressure measuring device, the pressure value is corrected only when the pressure value of hydrogen detected by the pressure sensor is equal to or greater than a predetermined value. Therefore, if the lower limit value of the pressure value that affects the measurement error of the pressure sensor is set as a predetermined value, correction is not performed even for a low pressure value that does not affect the measurement error of the pressure sensor. The pressure value can be accurately corrected.

[Application Example 2] The pressure measurement device according to Application Example 1, further including a filling detection unit that detects that the hydrogen storage unit is filled with the hydrogen, and the pressure correction unit includes the hydrogen storage unit. The time from when the hydrogen is filled into the part to the time when the pressure value of the hydrogen becomes less than the predetermined value is accumulated every time the filling is performed, and the pressure value of the hydrogen is determined according to the accumulated time. Pressure measuring device to correct.

  If it is a pressure measuring device of such an aspect, a pressure value can be amended according to time when a pressure sensor was used in a pressure value more than a predetermined value. Therefore, even if the pressure value output from the pressure sensor has changed over time, the pressure value can be accurately corrected.

[Application Example 3] The pressure measurement device according to Application Example 1, wherein the pressure measurement device is provided in a vehicle, and further, filling detection for detecting that the hydrogen storage unit is filled with the hydrogen. Distance on which the vehicle can travel before the hydrogen pressure reaches the predetermined value on the basis of the pressure portion, the pressure value of the charged hydrogen, and a predetermined fuel consumption indicating a distance travelable per unit pressure An estimated mileage calculation unit for obtaining an estimated mileage, and the pressure correction unit integrates the time until the mileage after the hydrogen storage unit is filled with the hydrogen reaches the estimated mileage. And a pressure measuring device for correcting the pressure value of the hydrogen according to the accumulated time.

  With such a pressure measuring device, the usage time of the pressure sensor can be integrated according to the travel distance of the vehicle, not the pressure value from the pressure sensor that may contain an error. Therefore, even if the pressure value output from the pressure sensor has changed over time, the pressure value can be accurately corrected.

[Application Example 4] The pressure measuring device according to Application Example 2 or Application Example 3, wherein the filling detection unit is configured to perform the hydrogen storage unit based on a change in the pressure value of the hydrogen output from the pressure sensor. A pressure measuring device for detecting whether or not the hydrogen is filled in the battery. With such a pressure measuring device, it is possible to detect whether hydrogen has been filled based on the pressure fluctuation of the hydrogen supplied from the hydrogen reservoir.

[Application Example 5] The pressure measurement device according to Application Example 2 or Application Example 3, further including a temperature sensor that detects a temperature of hydrogen stored in the hydrogen storage unit, wherein the filling detection unit includes the temperature A pressure measurement device that detects whether or not the hydrogen storage unit is filled with the hydrogen based on a change in temperature detected by a sensor. With this type of pressure measurement device, it is possible to detect whether hydrogen has been filled based on a change in the temperature of hydrogen generated when the hydrogen reservoir is filled with hydrogen.

[Application Example 6] The pressure measurement device according to Application Example 2 or Application Example 3, further including a communication unit that communicates with a hydrogen filling device that fills the hydrogen storage unit with hydrogen, and the filling detection unit includes: A pressure measuring device that detects whether or not the hydrogen reservoir is filled with the hydrogen based on the communication. With such a pressure measurement device, it is possible to detect whether hydrogen has been filled based on communication with a hydrogen filling device that fills the hydrogen reservoir with hydrogen.

[Application Example 7] In the pressure measurement device according to any one of Application Examples 1 to 6, the correction unit is configured based on the temperature of the hydrogen in addition to the accumulated time. Pressure measuring device that performs correction.

  With such a pressure measuring device, the pressure value is corrected by taking into account not only the time when the pressure sensor is used but also the temperature of hydrogen, so that the pressure value of hydrogen can be corrected more accurately. It becomes possible.

[Application Example 8] The pressure measurement device according to any one of Application Examples 1 to 7, a fuel cell as the hydrogen consuming device, a motor driven by electric power generated by the fuel cell, A vehicle comprising: a remaining amount calculation unit that calculates a remaining amount of hydrogen in the hydrogen storage unit based on a corrected pressure value output from the pressure measurement device.

  With such a vehicle, the pressure of hydrogen supplied to the fuel cell can be accurately corrected, so that the remaining amount of hydrogen in the hydrogen reservoir can be calculated with high accuracy.

  The present invention can be configured as a fuel cell system including a pressure measuring device and a pressure measuring method in addition to the above-described configuration as a pressure measuring device and a vehicle.

It is explanatory drawing which shows schematic structure of the electric vehicle 10 provided with the pressure measuring apparatus 100 as an Example of this invention. 3 is a cross-sectional view showing a schematic configuration of a pressure sensor 60. FIG. 3 is a graph showing output characteristics of a pressure sensor 60. It is a flowchart of the pressure measurement process in 1st Example. It is a flowchart of the pressure measurement process in 1st Example. It is a figure which shows the pressure change of the hydrogen gas output from the hydrogen tank. It is explanatory drawing which shows an example of the correction map. It is a flowchart of the pressure measurement process in 2nd Example. It is a figure which shows the structure of the electric vehicle 10c in 3rd Example. It is a graph which shows the temperature change and pressure change of hydrogen gas when hydrogen gas is filled into the hydrogen tank 12. It is a flowchart of the filling detection process performed in 3rd Example. It is a flowchart of the pressure measurement process performed in 3rd Example. It is a figure which shows the structure of the electric vehicle 10d in 4th Example. It is a flowchart of the filling detection process performed in 4th Example. It is a figure which shows an example of the map for determining the temperature coefficient K2 in 5th Example.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A-1. General configuration of electric vehicle:
A-2. Configuration of pressure sensor:
A-3. Pressure measurement process:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Example 5:

A. First embodiment:
A-1. General configuration of electric vehicle:
FIG. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle 10 including a pressure measuring device 100 as an embodiment of the present invention. In addition to the pressure measuring device 100, the electric vehicle 10 includes a hydrogen tank 12 as a hydrogen storage unit, an air compressor 14, a fuel cell 16 as a hydrogen consuming device, a secondary battery 18, a motor 20, an inverter 22, a control device 50, and the like. It has.

  A filling port 26 is connected to the hydrogen tank 12. The hydrogen tank 12 is filled with about 70 MPa of hydrogen gas from a hydrogen dispenser (not shown) installed in a hydrogen station or the like through the filling port 26. The hydrogen gas output from the hydrogen tank 12 through the shut-off valve 13 is decompressed to about 1.5 MPa by the pressure regulating valve 30 and supplied to the fuel cell 16. A pressure sensor 60 that detects the pressure of the hydrogen gas output from the hydrogen tank 12 is attached in the vicinity of the shutoff valve 13. In the following description, the term “hydrogen gas pressure” refers to the hydrogen gas pressure before being reduced by the pressure regulating valve 30. Although only one hydrogen tank 12 is shown in FIG. 1, the number is not particularly limited.

  The fuel cell 16 generates power by an electrochemical reaction between hydrogen gas supplied from the hydrogen tank 12 and oxygen in the air supplied from the air compressor 14. As the fuel cell 16, various types such as a polymer electrolyte fuel cell and a solid oxide fuel cell can be applied. The electric power generated by the fuel cell 16 is used for driving the motor 20 and for charging the secondary battery 18. The secondary battery 18 is used as a power source for driving the motor 20 together with the fuel cell 16.

  The inverter 22 converts a direct current output from the fuel cell 16 and the secondary battery 18 into a three-phase alternating current, and supplies the same to the motor 20. When the motor 20 is supplied with electric power via the inverter 22, the electric vehicle 10 is caused to travel by rotating a wheel (not shown).

  The control device 50 is configured by a logic circuit including a CPU, a RAM, a ROM, and an EEPROM. An ignition switch 31, an accelerator position sensor 32, a vehicle speed sensor 34, an inverter 22, an instrument panel 36, and a pressure measuring device 100 are connected to the control device 50. The control device 50 is a device that controls the overall operation of the electric vehicle 10. For example, the control device 50 controls the inverter 22 and adjusts the driving force of the motor 20 according to the accelerator depression amount detected by the accelerator position sensor 32. . The signal from the ignition switch 31 is also transmitted to the pressure measuring device 100 through the control device 50.

  The control device 50 includes a remaining amount calculation unit 52 and a travel distance calculation unit 54 as functional blocks realized by the logic circuit described above.

  The remaining amount calculation unit 52 receives the hydrogen pressure value from the pressure measuring device 100 and calculates the remaining amount of hydrogen in the hydrogen tank 12 according to the pressure value. The calculated remaining amount of hydrogen gas is displayed on the instrument panel 36. For example, when the pressure value input from the pressure measuring device 100 is 70 MPa, the remaining amount calculation unit 52 calculates the remaining amount of hydrogen as 100%, and the remaining amount decreases from 100% to 0% as the pressure value decreases from 70 MPa. The remaining amount of hydrogen gas is calculated using a predetermined function or map approaching.

  The travel distance calculation unit 54 calculates the travel distance of the electric vehicle 10 according to the pulse signal received from the vehicle speed sensor 34. The travel distance is displayed on the instrument panel 36 in the same manner as the remaining amount of hydrogen gas. The travel distance calculation unit 54 transmits the calculated travel distance to the pressure measurement device 100 for execution of a pressure measurement process described later. Further, when the ignition switch is turned off, the travel distance calculation unit 54 records the calculated travel distance in the EEPROM provided therein.

  The pressure measuring device 100 is configured by a logic circuit including a CPU, a RAM, a ROM, an EEPROM, and the like. The pressure measuring device 100 has a function of correcting an error in the pressure value of the hydrogen gas output from the pressure sensor 60. In order to realize this function, the pressure measuring device 100 includes a filling detection unit 110, an estimated travel distance calculation unit 120, and a pressure correction unit 130 as functional blocks realized by the above-described logic circuit. The ROM included in the pressure measuring device 100 stores a correction map 140 used for correcting the pressure value output from the pressure sensor 60. Note that, for example, a pressure value of hydrogen detected immediately before the ignition switch 31 is turned off is written in an EEPROM provided in the pressure measuring device 100 (details will be described later).

  The filling detection unit 110 detects whether or not the hydrogen tank 12 is filled with hydrogen gas. In the present embodiment, as described later, it is detected whether or not hydrogen gas is filled based on a change in the pressure of the hydrogen gas detected by the pressure sensor 60.

  The estimated travel distance calculation unit 120 is configured to increase the hydrogen pressure to a predetermined threshold value Pt based on the filled hydrogen pressure value and the predetermined fuel consumption indicating the distance that the electric vehicle 10 can travel per unit pressure. The distance that can be traveled (hereinafter referred to as “estimated travel distance Dm”) is calculated.

  When the hydrogen pressure value received from the pressure sensor 60 is equal to or greater than a predetermined threshold value Pt, the pressure correction unit 130 corrects the pressure value based on the usage time of the pressure sensor 60 and the correction map 140. In the present embodiment, the usage time of the pressure sensor 60 refers to the time that the pressure sensor 60 has been used at a pressure equal to or higher than the threshold value Pt described above. The threshold value Pt is set based on the pressure obtained by experimentally obtaining a pressure at which an output value may contain an error due to the characteristics of the pressure sensor 60.

  The pressure measurement device 100 transmits the hydrogen gas pressure value corrected by the pressure correction unit 130 to the control device 50. Based on the corrected pressure value transmitted in this way, the control device 50 calculates the remaining amount of hydrogen in the hydrogen tank 12 by the remaining amount calculation unit 52. Of course, when the pressure value of the hydrogen gas is not corrected by the pressure correction unit 130, the remaining amount calculation unit 52 calculates the remaining amount of hydrogen based on the uncorrected pressure value.

  The detailed functions and functions of the filling detection unit 110, the estimated travel distance calculation unit 120, the pressure correction unit 130, and the correction map 140 described above will be described in detail in the “pressure measurement process” described later.

A-2. Configuration of pressure sensor:
FIG. 2 is a cross-sectional view showing a schematic configuration of the pressure sensor 60. The pressure sensor 60 includes a metal stem 62 formed of a Fe—Ni alloy such as 42 alloy, or a low thermal expansion metal such as Kovar or SUS. The pressure sensor 60 further includes a housing 64 used for attachment to a pipe through which hydrogen gas flows, a screw member 66 that fixes the metal stem 62 inside the housing 64, and a metal terminal to which the pressure measuring device 100 is electrically connected. 68 or the like.

  The metal stem 62 is a substantially cylindrical member having a hole 72 having a lower end opened and a bottom at the upper end. Hydrogen gas output from the hydrogen tank 12 is introduced into the hole 72 through a hole 74 provided in the lower portion of the housing 64. The inner diameter of the hole 72 is about 2.5 mm, and the bottom is formed in a thin shape of 0.2 to 1.0 mm. Hereinafter, the thin-walled bottom portion is referred to as a diaphragm 76.

  A sensor substrate 80 on which a strain gauge 78 is mounted as a pressure detection element is bonded to the upper surface of the diaphragm 76 with low-melting glass. The electrical signal output from the strain gauge 78 is input to the pressure measuring device 100 through the metal terminal 68.

  As described above, hydrogen gas of a maximum of 70 MPa is introduced into the pressure sensor 60 configured as described above. Then, the diaphragm 76 is deformed by the pressure of the hydrogen gas. When the diaphragm 76 is deformed, the strain gauge 78 mounted on the sensor substrate 80 bonded to the upper surface thereof is also deformed. Then, an electric signal corresponding to the degree of deformation is output from the strain gauge 78 as a pressure value, and the pressure value is transmitted to the pressure measuring device 100.

  FIG. 3 is a graph showing output characteristics of the pressure sensor 60. In this graph, the output error of the pressure sensor 60 when the pressure of 70 MPa hydrogen gas is measured is indicated by “% FS (full scale)”. According to this graph, the output value of the pressure sensor 60 becomes larger than the original output value as the usage time elapses after the supply of hydrogen gas to the pressure sensor 60 is started. I understand. According to FIG. 3, for example, when the pressure sensor 60 is used for 5 years or more, an output error of around + 4.0% FS occurs. This is because when high-pressure hydrogen gas is introduced into the pressure sensor 60, the hydrogen gas permeates through the metal stem 62 and stays in the low-melting-point glass between the diaphragm 76 and the strain gauge 78. This is because the output of the strain gauge 78 shows a pressure value higher than the original pressure value. Therefore, in this embodiment, the output error of the pressure sensor 60 is corrected in the pressure measurement process described below.

A-3. Pressure measurement process:
4 and 5 are flowcharts of the pressure measurement process in the first embodiment. This pressure measurement process is executed by the pressure measurement device 100 when the ignition switch 31 is turned on. Hereinafter, the pressure measurement process will be described with reference to FIG. 6 showing the pressure change of the hydrogen gas output from the hydrogen tank 12.

  When this pressure measurement process is executed, first, the filling detection unit 110 of the pressure measurement device 100 calculates the pressure value detected by the pressure sensor 60 immediately before the ignition switch 31 is turned off last time. Is read from the EEPROM included in. The pressure value read here is the pressure value Pc after correction corrected by executing the pressure measurement process last time. Then, the filling detection unit 110 determines whether the pressure value Pc is less than a predetermined threshold value Pt (step S100). This threshold value Pt is predetermined based on the pressure value of hydrogen that affects the output of the pressure sensor 60, and can be set to 35 MPa, for example, as shown in FIG.

  When the pressure value Pc read from the EEPROM is less than the threshold value Pt, the filling detection unit 110 acquires the current hydrogen gas pressure value Pn from the pressure sensor 60. And it is judged whether the acquired present pressure value Pn is more than the threshold value Pt mentioned above (step S102). If the current pressure value Pn is equal to or greater than the threshold value Pt, the filling detection unit 110 determines that the hydrogen gas is filled in the hydrogen tank 12 while the ignition switch 31 is turned off. When the hydrogen gas is filled in the hydrogen tank 12, for example, the pressure of the hydrogen gas rises to 70 MPa as shown at timing t0 and timing t2 in FIG. If it is determined by the filling detection unit 110 that the hydrogen gas is filled, the pressure correction unit 130 of the pressure measuring device 100 continues based on the previous use time Tt of the pressure sensor 60 and the correction map 140. Then, a correction coefficient K for correcting the pressure value Pn is determined (step S104). That is, in this embodiment, the pressure measuring device 100 determines the correction coefficient K every time the hydrogen tank 12 is filled with hydrogen.

  FIG. 7 is an explanatory diagram showing an example of the correction map 140. In this figure, the horizontal axis indicates the usage time Tt of the pressure sensor 60, and the vertical axis indicates the correction coefficient K. As shown in this figure, in this embodiment, the correction coefficient K is set to be lower as the use time Tt of the pressure sensor 60 is longer. In the correction map 140, the correction coefficient K is set according to the usage time Tt of the pressure sensor 60 so as to cancel out the output fluctuation of the pressure sensor 60 shown in FIG. A detailed calculation method of the usage time Tt will be described later.

  When the correction coefficient K is determined as described above, the pressure measurement device 100 transmits a predetermined reset signal to the travel distance calculation unit 54 of the control device 50 and resets the travel distance Dn of the electric vehicle 10 to “0”. (Step S106). When the pressure measurement device 100 resets the travel distance Dn in this manner, the estimated travel distance calculation unit 120 then continues the distance that the electric vehicle 10 can travel before the hydrogen gas pressure value reaches the threshold value Pt (estimated travel distance). Dm) is calculated based on the following formulas (1) and (2) (step S108).

Pc = K · Pn (1)
Dm = (Pc−Pt) · Fc (2)

  In these equations, the pressure measuring apparatus 100 multiplies the current hydrogen gas pressure value Pn acquired from the pressure sensor 60 by the correction coefficient K determined in step S104 to obtain a corrected pressure value Pc. Then, the threshold value Pt described above is subtracted from the corrected pressure value Pc, and the subtracted value is multiplied by a predetermined fuel efficiency Fc (travel distance per unit pressure) of the electric vehicle 10. By performing such a calculation, the pressure measuring apparatus 100 can calculate the estimated travel distance Dm.

  If the pressure value read from the EEPROM in step S100 described above is equal to or greater than the threshold value Pt, the hydrogen gas is not filled when the ignition switch is turned off this time. In this case, the correction coefficient K and the estimated travel distance Dm are already determined by the pressure measurement process performed immediately before the hydrogen gas filling and before the previous time. Therefore, in this case, the pressure measuring device 100 skips the processes of steps S102 to S108 described above.

  The series of processes described above is a process that is executed only once immediately after the ignition switch 31 is turned on. Hereinafter, a process that is constantly executed during the operation of the electric vehicle 10 until the ignition switch 31 is turned off will be described.

  When the correction coefficient K and the estimated travel distance Dm are determined by the above-described processing, the pressure correction unit 130 of the pressure measuring device 100 acquires the current hydrogen gas pressure value Pn from the pressure sensor 60 (step S110). When the pressure value Pn is acquired, the pressure correction unit 130 performs correction by multiplying the acquired pressure value Pn by the correction coefficient K determined in step S104. Then, the corrected pressure value Pc is output to the control device 50 (step S112). By doing so, the remaining amount calculation unit 52 of the control device 50 can accurately calculate the remaining amount of hydrogen in the hydrogen tank 12.

  When the corrected pressure value Pc is output, the pressure correction unit 130 of the pressure measurement device 100 acquires the current travel distance Dn from the travel distance calculation unit 54 of the control device 50 (step S114). Then, it is determined whether the acquired current travel distance Dn is less than or equal to the estimated travel distance Dm calculated in step S108 (step S116). If the travel distance Dn is less than or equal to the estimated travel distance Dm, the pressure correction unit 130 integrates the usage time Tt of the pressure sensor 60 based on the following formula (3) (step S118). On the other hand, if the travel distance Dn exceeds the estimated travel distance Dm, the pressure correction unit 130 interrupts the accumulation of the usage time Tt of the pressure sensor 60 (step S120).

Tt ′ = Tt + Δt (3)
Tt ′ represents a new usage time after integration, and Δt represents a time elapsed from the previous execution of the process of step S118 to the current execution.

  In the present embodiment, as described above, by comparing the travel distance Dn and the estimated travel distance Dm, the pressure sensor 60 from the time when the hydrogen gas is filled to the time when the pressure of the hydrogen gas reaches the threshold value Pt. The usage time Tt can be integrated. The usage time Tt is an integrated value as long as the pressure sensor 60 is exposed to hydrogen gas having a pressure equal to or higher than the threshold value Pt. Therefore, this usage time Tt is also integrated when the electric vehicle 10 is stopped. For example, when hydrogen gas is filled in the hydrogen tank 12 at the timing t0 in FIG. 6, the usage time Tt until the timing t1 when the pressure value reaches the threshold value Pt regardless of whether the electric vehicle 10 is running or stopped. Is accumulated. After that, when the hydrogen gas is filled again, the use time Tt is continuously accumulated after the filling timing t2.

  Subsequently, the pressure measuring device 100 determines whether or not the ignition switch 31 is turned off (step S122). If the ignition switch 31 is turned off, the pressure measuring device 100 records the corrected pressure value Pc, the estimated travel distance Dm, and the usage time Tt in the EEPROM (step S124), and ends the pressure measurement process. To do. At this time, the travel distance Dn is recorded by the control device 50. On the other hand, if the ignition switch 31 is not turned off, the pressure measuring device 100 repeatedly executes the processes of steps S110 to S122 described above.

  In addition, the process of step S110-S124 mentioned above is a process performed when it is judged in step S102 that the present pressure value Pn is more than threshold value Pt. On the other hand, if it is determined in step S102 that the current hydrogen gas pressure value Pn is less than the threshold value Pt, hydrogen gas is not filled, or hydrogen gas is filled, The pressure stays below the threshold value Pt, and the pressure value output from the pressure sensor 60 does not include an error or is negligible even if included. Therefore, in this case, the processing shown in FIG. 5 is always executed during operation of the electric vehicle 10 without determining the correction coefficient K. That is, the pressure value Pn of hydrogen gas is acquired from the pressure sensor 60 (step S140), and the acquired pressure value Pn is output to the control device 50 as it is (step S142). Then, the processes of step S140 and step S142 are always executed until the ignition switch 31 is turned off (step S144).

  The pressure measuring apparatus 100 according to the present embodiment described above is configured to detect the hydrogen gas pressure value Pn detected by the pressure sensor 60 only when the hydrogen gas pressure value Pn output from the hydrogen tank 12 is equal to or greater than a predetermined threshold value Pt. Correct. Therefore, because of the characteristics of the pressure sensor 60, the pressure is not corrected to a pressure at which the output does not include an error, so that the hydrogen gas pressure can be corrected accurately.

  Moreover, even if the pressure measuring device 100 of the present embodiment includes an error in the pressure value Pn output from the pressure sensor 60 due to the filling of high-pressure hydrogen gas, the error is included in the usage time Tt of the pressure sensor 60. Correction can be made with a correction coefficient K determined accordingly. Therefore, even if the error included in the pressure value output from the pressure sensor 60 changes over time, it is possible to accurately correct the error.

  Further, the pressure measuring device 100 according to the present embodiment obtains a distance (estimated travel distance Dm) that can be traveled until the hydrogen gas after filling reaches the threshold value Pt based on the fuel consumption of the electric vehicle 10. Then, by comparing the estimated travel distance Dm and the current travel distance Dn, it is determined whether the hydrogen gas pressure has decreased to the threshold value Pt. Therefore, it is possible to determine whether the pressure of the hydrogen gas has decreased to the threshold value Pt without using an output value from the pressure sensor 60 that may contain an error.

B. Second embodiment:
Next, a second embodiment of the present invention will be described. In the first embodiment described above, when the usage time Tt is integrated, it is determined whether the hydrogen gas pressure has decreased to the threshold value Pt by comparing the estimated travel distance Dm calculated in advance with the current travel distance Dn. did. On the other hand, in the second embodiment, the pressure value Pn detected by the pressure sensor 60 is used as it is to determine whether the pressure of the hydrogen gas has decreased to the threshold value Pt. In addition, the pressure measuring apparatus 100 of 2nd Example can abbreviate | omit the estimated traveling distance calculation part 120 (refer FIG. 1) from the structure.

  FIG. 8 is a flowchart of the pressure measurement process in the second embodiment. The pressure measurement process of the second embodiment is executed by the pressure measurement device 100 when the ignition switch 31 is turned on, as in the first embodiment. When this pressure measurement process is executed, first, the filling detection unit 110 of the pressure measurement device 100 calculates the pressure value detected by the pressure sensor 60 immediately before the ignition switch 31 is turned off last time. Is read from the EEPROM included in. Then, the filling detection unit 110 determines whether the pressure value Pc is less than a predetermined threshold value Pt (step S200).

  When the pressure value Pc read from the EEPROM is less than the threshold value Pt, the filling detection unit 110 acquires the current hydrogen gas pressure value Pn from the pressure sensor 60. Then, it is determined whether or not the acquired current pressure value Pn is greater than or equal to the threshold value Pt described above (step S202). If the current pressure value Pn is equal to or greater than the threshold value Pt, the filling detection unit 110 determines that the hydrogen gas is filled in the hydrogen tank 12 while the ignition switch 31 is turned off. When it is determined by the filling detection unit 110 that hydrogen gas is filled, the pressure correction unit 130 of the pressure measuring device 100 calculates the pressure value Pn based on the previous use time Tt of the pressure sensor 60 and the correction map 140. A correction coefficient K for correction is determined (step S204).

  When the pressure value read from the EEPROM in step S200 described above is equal to or greater than the threshold value Pt, the correction coefficient K has already been determined by the previous pressure measurement process performed immediately after the hydrogen gas filling. It will be. Therefore, in this case, the pressure measuring device 100 skips the processes of steps S202 to S204 described above.

  When the correction coefficient K is determined by the above-described processing, the pressure correction unit 130 of the pressure measurement device 100 acquires the current hydrogen gas pressure value Pn from the pressure sensor 60 (step S210). When the pressure value Pn is acquired, the pressure correction unit 130 performs correction by multiplying the acquired pressure value Pn by the correction coefficient K determined in step S204. Then, the corrected pressure value Pc is output to the control device 50 (step S212).

  When the corrected pressure value Pc is output, the pressure correction unit 130 of the pressure measuring device 100 determines whether or not the current pressure value Pn acquired in step S210 is greater than or equal to the threshold value Pt (step S216). If the pressure value Pn is greater than or equal to the threshold value Pt, the pressure correction unit 130 integrates the usage time Tt (step S218). On the other hand, if the pressure value Pn is less than the threshold value Pt, the pressure correction unit 130 interrupts the integration of the usage time Tt (step S220).

  Subsequently, the pressure measuring device 100 determines whether or not the ignition switch 31 is turned off (step S222). If the ignition switch 31 is turned off, the pressure measuring device 100 records the corrected pressure value Pc and the usage time Tt in the EEPROM (step S224), and ends the pressure measuring process. On the other hand, if the ignition switch 31 is not turned off, the pressure measuring device 100 repeatedly executes the processes of steps S210 to S222 described above.

  If it is determined in step S102 that the current hydrogen gas pressure value Pn is less than the threshold value Pt, the hydrogen gas is not filled at all, or even if hydrogen gas is filled, the pressure Remains below the threshold value Pt, and the pressure value output from the pressure sensor 60 does not include an error or is negligible even if included. Therefore, in this case, as in the first embodiment, the process shown in FIG. 5 is always executed during operation of the electric vehicle 10 without determining the correction coefficient K.

  In the second embodiment described above, the pressure value Pn detected by the pressure sensor 60 is used as it is to determine whether the hydrogen gas pressure has decreased to the threshold value Pt. Therefore, since the calculation of the estimated travel distance Dm can be omitted, the processing content can be simplified. As shown in FIG. 3, the secular change of the pressure value output from the pressure sensor 60 appears over a long period of year. On the other hand, the hydrogen gas filled in the hydrogen tank 12 decreases to the threshold value Pt for a period of one to two months at the longest. Therefore, even if it is determined whether the pressure of the hydrogen gas has reached the threshold value Pt using the pressure value Pn detected by the pressure sensor 60 as it is as in this embodiment, it is practically necessary to integrate the use time Tt. , No problem.

C. Third embodiment:
Next, a third embodiment of the present invention will be described. In the first and second embodiments described above, immediately after the ignition switch 31 is turned on, a change in the pressure of the hydrogen gas is detected to determine whether or not the hydrogen tank 12 is filled with the hydrogen gas. . On the other hand, in the third embodiment, it is determined whether the hydrogen gas is filled based on the temperature change of the hydrogen gas filled in the hydrogen tank 12.

  FIG. 9 is a diagram showing a configuration of an electric vehicle 10c in the third embodiment. As shown in FIG. 9, a temperature sensor 61 is built in the hydrogen tank 12 of this embodiment, and this temperature sensor 61 is connected to the pressure measuring device 100c. Other configurations are the same as those in the first embodiment except that the pressure measuring device 100c does not include the estimated travel distance calculation unit 120.

  FIG. 10 is a graph showing changes in temperature and pressure of hydrogen gas when the hydrogen tank 12 is filled with hydrogen gas. Generally, the time required to fill the hydrogen tank 12 with hydrogen gas is about 10 minutes. Hydrogen gas is supplied to the hydrogen tank 12 after being adiabatically compressed from an external hydrogen dispenser during this 10 minutes. For this reason, the temperature of the hydrogen in the hydrogen tank 12 rapidly rises due to this adiabatic compression, and the temperature rises to about 80 to 85 degrees within a few minutes from the start of filling. When the filling of hydrogen gas is completed, this temperature gradually decreases and becomes equal to the ambient outside air temperature. Therefore, in this embodiment, it is determined whether the hydrogen tank 12 is filled with hydrogen by detecting the temperature change of the hydrogen gas.

  FIG. 11 is a flowchart of the filling detection process executed in the third embodiment. This filling detection process is repeatedly executed by the pressure measuring device 100c while the ignition switch 31 is turned off. That is, in the present embodiment, even when the ignition switch 31 is turned off, the power is supplied from the secondary battery 18 to the pressure measuring device 100c.

  When this filling detection process is executed, the filling detection unit 110 of the pressure measuring device 100c detects the temperature T of the hydrogen gas in the hydrogen tank 12 by the temperature sensor 61 (step S300). And it is judged whether the detected temperature T is 70 degreeC or more (step S302). If the detected temperature T is 70 ° C. or higher, the filling detection unit 110 determines that the hydrogen tank 12 is filled with hydrogen, and a flag indicating that hydrogen gas has been filled (hereinafter referred to as “filling flag”). ) Is turned on, and the state of the flag is recorded in the EEPROM (step 304). On the other hand, if the detected temperature T is less than 70 ° C., the process of step S304 is skipped. Subsequently, the filling detection unit 110 determines whether or not the ignition switch 31 is turned on (step S306). If the ignition switch 31 is turned on, the filling detection unit 110 ends the filling detection process. On the other hand, if the ignition switch 31 remains off, the filling detection unit 110 repeatedly executes the processes of steps S300 to S306 described above. According to the filling detection process described above, the pressure measuring device 100c can monitor whether the hydrogen gas is filled in the hydrogen tank 12 while the ignition switch 31 is turned off.

  FIG. 12 is a flowchart of the pressure measurement process executed in the third embodiment. This pressure detection process is a process executed by the pressure measurement device 100 when the ignition switch 31 is turned on. That is, in this embodiment, when the filling detection process shown in FIG. 11 is completed, the pressure measurement process is continuously executed. The pressure measurement process of the third embodiment is different from the pressure measurement process (FIG. 4) of the first embodiment only in steps S100, S102, and S124. Therefore, in FIG. 12, the same processing numbers as those shown in FIG. 4 are given the same step numbers as those in FIG.

  When this pressure measurement process is executed, the pressure measurement device 100c first acquires the hydrogen gas pressure value Pn from the pressure sensor 60, and determines whether the pressure value Pn is equal to or greater than the threshold value Pt (step S100b). ). If the pressure value Pn is less than the threshold value Pt, there is no need to correct the pressure value Pn, so the processing shown in FIG. 5 is executed. On the other hand, if the pressure value Pn is greater than or equal to the threshold value Pt, the pressure measuring device 100c determines whether the state of the filling flag recorded in the EEPROM is on (step S102b). If the filling flag is on, the hydrogen gas is filled in the hydrogen tank 12 while the ignition switch 31 is off. Therefore, the pressure measuring device 100c performs processing such as determination of the correction coefficient K in steps S104 to S108. On the other hand, if the filling flag is off, the correction coefficient K and the like have already been determined by the pressure measurement process before the previous time, so the processes of steps S104 to S108 are skipped. Hereinafter, in the present embodiment, processing similar to steps S110 to S122 of the pressure measurement processing of the first embodiment is executed. Finally, when the ignition switch 31 is turned off (step S122), in the present embodiment, the pressure measuring device 100 records the corrected pressure value Pc, the estimated travel distance Dm, and the usage time Tt in the EEPROM. The filling flag is turned off, and the state of the flag is written in the EEPROM (step S124b).

  According to the pressure measuring device 100c of the third embodiment described above, it is possible to determine whether the hydrogen tank 12 is filled with hydrogen based on the temperature change of the hydrogen gas in the hydrogen tank 12. In the pressure measurement process of the present embodiment, the processes other than steps S100b, S102b, and S124b shown in FIG. 12 are performed in the same manner as the pressure measurement process of the first embodiment. The same process as the example process (specifically, steps S204 to S222) may be executed. That is, the method of determining the filling of the hydrogen gas based on the temperature change of the hydrogen gas can be similarly applied to both the first embodiment and the second embodiment.

  In the present embodiment, the case where the temperature of the hydrogen in the hydrogen tank 12 rises to about 80 to 85 degrees when hydrogen gas is filled has been described. This rise temperature depends on the type of the hydrogen tank 12 and the hydrogen gas. It depends on the cooling capacity of the precooler installed on the hydrogen station side to suppress the temperature rise. Therefore, the temperature (70 ° C. in this embodiment) to be compared in step S302 of the filling detection process shown in FIG. 11 is appropriately set to other values depending on the type of the hydrogen tank 12 and the cooling capacity of the precooler. Is possible.

  Further, in this embodiment, when the temperature of the hydrogen gas in the hydrogen tank 12 rises to a predetermined temperature, it is determined that the hydrogen is filled, but such determination can be realized by other methods. For example, when the temperature of the hydrogen gas that has risen per unit time (for example, 1 second to 1 minute) is equal to or higher than a predetermined value (for example, a temperature between 5 and 20 degrees), it is determined that the hydrogen gas is filled. It is also possible to do.

D. Fourth embodiment:
In the third embodiment described above, it was determined whether the hydrogen gas was filled in the hydrogen tank 12 based on the temperature change of the hydrogen gas. On the other hand, in the fourth embodiment, it is determined whether or not hydrogen gas is filled in the hydrogen tank 12 by directly communicating with the hydrogen dispenser 90 installed in the hydrogen station or the like.

  FIG. 13 is a diagram illustrating a configuration of an electric vehicle 10d according to the fourth embodiment. In this embodiment, an infrared transmitter 27 is built in the filling port 26 to which the hydrogen dispenser 90 is connected. The pressure measuring device 100d can directly communicate with the infrared receiver 91 provided on the hydrogen dispenser 90 side via the infrared transmitter 27. In this embodiment, the hydrogen tank 12 has a built-in temperature sensor 61 as in the third embodiment.

  FIG. 14 is a flowchart of the filling detection process executed in the fourth embodiment. This filling detection process is executed by the pressure measuring device 100c while the ignition switch 31 is turned off. That is, in the present embodiment, even when the ignition switch 31 is turned off, the power is supplied from the secondary battery 18 to the pressure measuring device 100c.

  When this filling detection process is executed, the filling detection unit 110 of the pressure measuring device 100d determines whether the ignition switch 31 is off (step S400). When the ignition switch 31 is turned on, the pressure measuring device 100d ends the filling detection process. On the other hand, when the ignition switch 31 is off, the filling detection unit 110 attempts to communicate with the infrared receiver 91 on the hydrogen dispenser 90 side using the infrared transmitter 27 provided in the filling port 26. Then, it is determined whether the hydrogen dispenser 90 is connected to the filling port 26 (step S402). If the hydrogen dispenser 90 is not connected, the pressure measuring device 100d returns the process to step S400.

  When the hydrogen dispenser 90 is connected to the filling port 26, the pressure measuring device 100d performs a hydrogen filling process (step S404). This hydrogen filling process is a process in which the pressure measurement device 100d and the hydrogen dispenser 90 fill hydrogen gas while communicating with each other based on the standard of “SAE J2799”. Specifically, the pressure measuring device 100d sequentially transmits information indicating the temperature and pressure of the hydrogen gas flowing into the hydrogen tank 12 to the hydrogen dispenser 90. Upon receiving this information, the hydrogen dispenser 90 adjusts the supply speed (pressure) of the hydrogen gas so that the temperature of the hydrogen gas does not rise to 85 ° C. or higher, and supplies the hydrogen gas to the hydrogen tank 12. As described above, the pressure measuring device 100d and the hydrogen dispenser 90 can perform the filling of the hydrogen gas quickly while suppressing the temperature rise of the hydrogen gas by communicating with each other.

  The filling detection unit 110 determines whether the filling of hydrogen gas is completed by the hydrogen filling process executed in step S404 (step S406). When the filling of hydrogen gas is completed, the filling detection unit 110 turns on the filling flag (step S408), writes the state of the flag in the EEPROM, and ends the filling detection process. If the filling of hydrogen gas is not completed, the filling detecting unit 110 returns the process to step S404 and continues the hydrogen filling process.

  In the present embodiment, when the filling detection process described above is completed, a process similar to the pressure measurement process described in the third embodiment is executed. That is, it is determined whether or not to determine the correction coefficient K or the like based on the state of the filling flag recorded in the EEPROM. According to the pressure measuring device 100d of the present embodiment described above, it is determined whether or not the hydrogen gas is filled in the hydrogen tank 12 by directly communicating with the hydrogen dispenser 90. It becomes possible to judge whether it has been filled.

E. Example 5:
In each of the above-described embodiments, the correction coefficient K for correcting the pressure value is determined according to the usage time Tt of the pressure sensor 60. On the other hand, in this embodiment, the correction coefficient K is determined in consideration of not only the use time Tt of the pressure sensor 60 but also the temperature T of the hydrogen gas.

  Specifically, for example, prior to integrating the usage time Tt in step S118 of the pressure measurement process (FIG. 4) of the first embodiment, the pressure measurement device 100 first uses the temperature sensor 61 to perform hydrogenation. Measure the temperature of the gas. And the temperature coefficient K2 according to the temperature of this hydrogen gas is determined based on a predetermined map, and the usage time Tt is obtained based on the following equation (4) instead of the above equation (3). In this equation, Δt is multiplied by a temperature coefficient K2.

  Tt ′ = Tt + K2 · Δt (4)

  FIG. 15 is a diagram illustrating an example of a map for determining the temperature coefficient K2. As shown in this figure, the temperature coefficient K2 is set to show a larger value as the temperature of the hydrogen gas is higher.

  As described above, when the use time Tt is calculated using the temperature coefficient K2 in step S118, the use time Tt indicates a longer time than the original use time as the temperature of the hydrogen gas increases. It will be. Conversely, if the temperature of the hydrogen gas is low, the time is shorter than the original use time. Therefore, in step S104 of the pressure measurement process of FIG. 4, the correction coefficient K is determined according to the temperature of the hydrogen gas and the usage time of the pressure sensor 60.

  According to the fifth embodiment described above, the pressure value output from the pressure sensor 60 is corrected according to not only the usage time of the pressure sensor 60 but also the usage time of the pressure sensor 60 and the temperature of the hydrogen gas. It becomes possible to do. Due to the characteristics of the pressure sensor 60, it has been found that the higher the temperature of the introduced hydrogen gas, the faster the output value changes with time. Therefore, according to the present embodiment, the output value of the pressure sensor 60 can be corrected more accurately.

  In the present embodiment, the method of reflecting the temperature of the hydrogen gas in the output value of the pressure sensor 60 has been described by taking the pressure measurement process of the first embodiment as an example. However, reflecting the temperature of the hydrogen gas in the output value of the pressure sensor 60 is not limited to the first embodiment but can be applied to all other embodiments.

  Further, in this embodiment, the temperature of hydrogen gas is reflected in the correction of the output value of the pressure sensor by adjusting the use time Tt by the temperature coefficient K2. However, in addition to this, for example, the correction coefficient K may be obtained by a map or a function in which the correction coefficient K is determined according to two factors of the use time Tt and the temperature of the hydrogen gas.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various configurations can be adopted without departing from the spirit of the present invention.

  For example, in each of the above-described embodiments, the correction coefficient K is determined only once for each hydrogen gas filling. On the other hand, for example, every time the ignition switch 31 is turned on, the correction coefficient K may be determined. Further, the correction coefficient K may be determined in real time in accordance with the use time Tt that is sequentially accumulated while the electric vehicle 10 is traveling.

  In each of the above-described embodiments, the present invention is applied to the case where the pressure value of hydrogen gas supplied to the in-vehicle fuel cell 16 is corrected. However, the present invention is not limited to the in-vehicle fuel cell 16, but is also applicable to a case where the pressure value of hydrogen gas supplied to a stationary fuel cell or other hydrogen consuming device is corrected. .

DESCRIPTION OF SYMBOLS 10, 10c, 10d ... Electric vehicle 12 ... Hydrogen tank 13 ... Shut-off valve 14 ... Air compressor 16 ... Fuel cell 18 ... Secondary battery 20 ... Motor 22 ... Inverter 26 ... Filling port 27 ... Infrared transmitter (vehicle side)
DESCRIPTION OF SYMBOLS 30 ... Pressure adjustment valve 31 ... Ignition switch 32 ... Accelerator position sensor 34 ... Vehicle speed sensor 36 ... Instrument panel 50 ... Control apparatus 52 ... Remaining amount calculation part 54 ... Travel distance calculation part 60 ... Pressure sensor 61 ... Temperature sensor 62 ... Metal Stem 64 ... Housing 66 ... Screw member 68 ... Metal terminal 72 ... Hole 76 ... Diaphragm 78 ... Strain gauge 80 ... Sensor substrate 90 ... Hydrogen dispenser 91 ... Infrared receiver (hydrogen dispenser side)
DESCRIPTION OF SYMBOLS 100,100c, 100d ... Pressure measuring device 110 ... Filling detection part 120 ... Estimated travel distance calculation part 130 ... Pressure correction part 140 ... Correction map

Claims (8)

A pressure measuring device for measuring the pressure of hydrogen,
A hydrogen reservoir for storing hydrogen to be supplied to the hydrogen consuming device;
A metal member provided with a hole having one end opened and a bottom at the other end into which at least a part of hydrogen supplied from the hydrogen reservoir is introduced, and the hole on the outer surface of the metal member A pressure sensor comprising: a pressure detection element provided at a position facing the bottom surface of the unit; and an output unit that outputs an electrical signal obtained by the pressure detection element as a pressure value indicating the hydrogen pressure;
A pressure measurement device comprising: a correction unit that corrects the pressure value when the pressure value output from the pressure sensor is equal to or greater than a predetermined value. The pressure measuring device according to claim 1,
Furthermore, a filling detection unit that detects that the hydrogen storage unit is filled with the hydrogen,
The correction unit integrates the time from the time when it is detected that the hydrogen storage unit is filled with the hydrogen to the time when the pressure value of the hydrogen decreases to the predetermined value. A pressure measuring device that corrects the pressure value accordingly. The pressure measuring device according to claim 1,
The pressure measuring device is provided in a vehicle,
Further, a filling detection unit that detects that the hydrogen storage unit is filled with the hydrogen,
Based on the pressure value of the hydrogen when it is detected that the hydrogen reservoir is filled with the hydrogen and the predetermined fuel consumption indicating the distance that the vehicle can travel per unit pressure, the pressure of the hydrogen An estimated mileage calculating unit for obtaining an estimated mileage that is a distance that the vehicle can travel before the value reaches the predetermined value;
The correction unit integrates the time until the travel distance of the vehicle reaches the estimated travel distance from the time when it is detected that the hydrogen storage unit is filled with the hydrogen, and the accumulated time is A pressure measuring device that corrects the pressure value accordingly. The pressure measuring device according to claim 2 or 3, wherein
The filling detection unit is a pressure measurement device that detects whether or not the hydrogen storage unit is filled with the hydrogen based on a change in the pressure value output from the pressure sensor. The pressure measuring device according to claim 2 or 3, wherein
Furthermore, a temperature sensor for detecting the temperature of hydrogen stored in the hydrogen storage unit is provided,
The pressure detector is configured to detect whether or not the hydrogen storage unit is filled with the hydrogen based on a change in temperature detected by the temperature sensor. The pressure measuring device according to claim 2 or 3, wherein
And a communication unit that communicates with a hydrogen filling device that fills the hydrogen storage unit with hydrogen.
The filling detection unit is a pressure measurement device that detects whether or not the hydrogen storage unit is filled with the hydrogen based on the communication. The pressure measuring device according to any one of claims 1 to 6,
The pressure measurement device, wherein the correction unit performs the correction based on the temperature of the hydrogen in addition to the accumulated time. A pressure measuring device according to any one of claims 1 to 7,
A fuel cell as the hydrogen consuming device;
A motor driven by the power generated by the fuel cell;
A vehicle comprising: a remaining amount calculation unit that calculates a remaining amount of hydrogen in the hydrogen storage unit based on a corrected pressure value output from the pressure measurement device.

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