Tire air pressure monitoring system and tire air pressure monitoring method

Abstract

To provide a tire air pressure monitoring system and a tire air pressure monitoring method which can improve maintainability of a tire through monitoring leakage status of air of the tire.SOLUTION: A tire air pressure monitoring system 100 comprises: an information acquisition part 32; a change state calculation part 33; and a determination part 34. The information acquisition part 32 acquires measuring data through air pressure sensors 11 installed in a plurality of tires 1 attached to a vehicle. The change state calculation part 33 calculates a change state of air pressure of respective tires 1 based on the measuring data acquired by the information acquisition part 32. The determination part 34 determines an occurrence state of air leakage of the tire 1 based on the change state calculated by the change state calculation part 33.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tire pressure monitoring system and a tire pressure monitoring method for managing tires mounted on a vehicle. [Background technology]

[0002] Tires mounted on a vehicle are set to an appropriate air pressure, and if the air pressure drops, the tires are filled with air as part of maintenance so that the appropriate air pressure is restored.

[0003] A conventional tire pressure warning system is described in Patent Document 1. This tire pressure warning system is composed of a TPMS sensor transmitter and a TPMS receiver, which are internal pressure acquisition devices that acquire the internal pressure of each tire 5 of a vehicle, and an information terminal device that determines whether a malfunction, such as a puncture or natural pressure reduction, is occurring based on the change in the internal pressure of each tire received from the TPMS receiver, and displays a warning according to the malfunction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-76748 A Summary of the Invention [Problem to be solved by the invention]

[0005] The tire pressure warning system described in Patent Document 1 compares the air pressure of each tire with a threshold value to determine whether the tire is punctured. The inventors of the present invention considered that by monitoring conditions that occur in tires, such as slow leaks and slow punctures, in which loss of air is relatively likely to progress, it would be possible to support tire maintenance to be performed at an appropriate time, and that there would be room for improving tire maintainability.

[0006] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a tire pressure monitoring system and a tire pressure monitoring method that can monitor the deflation status of tires and improve tire maintainability. [Means for solving the problem]

[0007] A tire pressure monitoring system according to one embodiment of the present invention includes an information acquisition unit that acquires measurement data from air pressure sensors provided on multiple tires mounted on a vehicle, a change state calculation unit that calculates a change state of the air pressure of each tire based on the measurement data acquired by the information acquisition unit, and a judgment unit that judges the occurrence of air loss in a tire based on the change state calculated by the change state calculation unit.

[0008] Another aspect of the present invention is a tire pressure monitoring method, which includes an information acquiring step of acquiring measurement data from air pressure sensors provided on a plurality of tires mounted on a vehicle, a change state calculating step of calculating a change state of the air pressure of each tire based on the measurement data acquired in the information acquiring step, and a determination step of determining whether air loss has occurred in a tire based on the change state calculated in the change state calculating step. Effect of the Invention

[0009] According to the present invention, the deflation status of a tire can be monitored, and tire maintainability can be improved. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an overall configuration of a tire pressure monitoring system according to an embodiment; [Diagram 2] 2 is a block diagram showing a functional configuration of the tire pressure monitoring device; FIG. [Diagram 3] 4 is a flowchart showing a procedure for determining whether air has leaked, performed by a tire pressure management system. [Figure 4]11 is a graph showing an example of a tire pressure that is not determined to be a slow leak. [Diagram 5] 1 is a graph showing an example of a tire pressure that is determined to be a slow leak. [Figure 6] 1 is a graph showing an example of a tire pressure at which a slow puncture is determined; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below based on preferred embodiments with reference to Figures 1 to 6. The same or equivalent components and members shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The dimensions of the members in each drawing are enlarged or reduced as appropriate for ease of understanding. Some of the members that are not important for explaining the embodiments are omitted in each drawing.

[0012] (Embodiment) 1 is a schematic diagram showing the overall configuration of a tire pressure monitoring system 100 according to an embodiment. The tire pressure monitoring system 100 includes a sensor 10, a vehicle measurement device 20, a tire pressure monitoring device 30, and a user terminal device 40. The tire pressure monitoring system 100 collects and manages information such as the air pressure and temperature of tires 1 measured by sensors 10 disposed on multiple tires 1 mounted on a vehicle 7. The vehicle 7 is, for example, a transport truck or the like whose operation is managed by a transport company or the like. The vehicle 7 is equipped with multiple tires 1.

[0013] The tire pressure monitoring device 30 of the tire pressure monitoring system 100 calculates the change state, such as the rate of change in air pressure, from the measurement data of the tire pressure of a plurality of tires 1. The tire pressure monitoring device 30 determines the occurrence of air loss in the tire 1, such as slow leak or slow puncture, based on the calculated change state, such as the rate of change in the tire air pressure.

[0014] When the tire pressure monitoring device 30 determines that air loss has occurred in the tire 1, it generates alert information and notifies the outside. The tire pressure monitoring device 30 notifies the outside by displaying the alert information on a display device that the device itself has. The tire pressure monitoring device 30 also notifies the outside by sending an email or the like containing the alert information to the user.

[0015] The user visually recognizes the alert information displayed on the display device and becomes aware of the alert information. The user also receives e-mails or the like via the user terminal device 40 and becomes aware of the alert information. The user becomes aware of the alert information notified to the outside by the tire pressure monitoring device 30 and plans maintenance for the tires 1 mounted on the vehicle 7. Maintenance for the tires 1 includes, for example, inspecting the tires 1 and replacing the tires 1. The tire pressure monitoring system 100 can improve the maintainability of the tires 1 by providing information on the occurrence of air loss from the tires 1, such as slow leaks and slow punctures.

[0016] 2 is a block diagram showing the functional configuration of the tire pressure monitoring device 30. The sensor 10 includes an air pressure sensor 11 and a temperature sensor 12 disposed in the tire 1. The air pressure sensor 11 measures the tire air pressure. The temperature sensor 12 measures the tire temperature. The air pressure sensor 11 and the temperature sensor 12 are disposed, for example, in an air valve of the tire 1. The temperature sensor 12 may be disposed directly in the tire 1 to accurately measure the temperature of the tire 1.

[0017] The vehicle measurement device 20 accumulates measurement data of tire pressure and tire temperature measured by the sensor 10, and transmits the measurement data to the tire pressure monitoring device 30 via the communication network 8. The vehicle measurement device 20 transmits the stored measurement data to the tire pressure monitoring device 30, for example, every few minutes to every tens of minutes. The time interval at which the vehicle measurement device 20 transmits the measurement data to the tire pressure monitoring device 30 is not limited to every few minutes to every tens of minutes. The measurement data transmitted from the vehicle measurement device 20 to the tire pressure monitoring device 30 also includes information on the mounting position of each measured tire on the axle arrangement.

[0018] The tire pressure monitoring device 30 has a communication unit 31, an information acquisition unit 32, a change state calculation unit 33, a determination unit 34, a notification unit 35, a display unit 36, and a storage unit 37. Each unit in the tire pressure monitoring device 30 can be realized in terms of hardware by electronic processing circuits consisting of electronic elements such as a computer CPU, or mechanical parts, and in terms of software by a computer program, but here, functional blocks realized by the cooperation of these are depicted. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various forms by combining hardware and software.

[0019] The communication unit 31 is connected to the communication network 8 by wireless or wired communication, and communicates with the vehicle measurement device 20. The information acquisition unit 32 acquires the measurement data of the tire pressure and tire temperature transmitted by the vehicle measurement device 20 via the communication unit 31. The measurement data acquired by the information acquisition unit 32 is assumed to be associated with the identification information of the vehicle 7. The information acquisition unit 32 stores the acquired measurement data of the tire pressure and tire temperature in the memory unit 37. The information acquisition unit 32 also outputs the acquired tire pressure information to the change state calculation unit 33.

[0020] The storage unit 37 is a storage device configured by, for example, an SSD (Solid State Drive), a hard disk, a CD-ROM, a DVD, etc. The storage unit 37 stores vehicle management information 37a, sensor measurement data 37b, change state data 37c, and determination result information 37d.

[0021] The vehicle management information 37a is information about a plurality of vehicles 7 managed by, for example, a transportation company, and includes the name of the vehicle 7, the identification information of the vehicle 7 given to each vehicle, axle arrangement information, etc. The axle arrangement information includes information on the mounting position of tires on the axle arrangement.

[0022] The sensor measurement data 37b is measurement data of tire pressure and tire temperature acquired by the information acquisition unit 32 corresponding to each vehicle 7 included in the vehicle management information 37a. The sensor measurement data 37b includes information on the date and time when the tire pressure and tire temperature were measured. The change state data 37c is data on the change state, such as the rate of change of tire pressure, calculated by the change state calculation unit 33. The judgment result information 37d is generated by the judgment unit 34 and stored in the memory unit 37.

[0023] The change state calculation unit 33 calculates a change state such as a change rate of the tire air pressure based on the measurement data acquired by the information acquisition unit 32 within a predetermined period. The change state calculation unit 33 calculates the change rate of the tire air pressure for the change state of the air pressure of all the tires 1 mounted on the vehicle 7. The change state calculation unit 33 outputs the calculated change state such as the change rate of the tire air pressure to the storage unit 37 and stores it in the storage unit 37 as change state data 37c. The change state data 37c includes the change rate of the tire air pressure, identification information of the corresponding vehicle 7, information on the mounting position of the tire 1 on the axle arrangement, date and time information, etc. The change state calculation unit 33 calculates the change rate of the tire air pressure as an absolute value, for example. Hereinafter, a case where the change state of the tire air pressure is calculated by the change state calculation unit 33 will be described as an example.

[0024] The change state calculation unit 33 determines a regression line for the measurement data of the tire pressure measured within the predetermined period, for example, from one week to one month, and calculates the slope of the regression line as the rate of change in the tire pressure. The predetermined period for the change state calculation unit 33 to acquire the measurement data for determining the regression line is not limited to the above example, and may be from several days to one week, or may be a period longer than one month. The change state calculation unit 33 may calculate the rate of change in the tire pressure using a known statistical method, without being limited to calculating the rate of change based on the regression line.

[0025] Also, the change state calculation unit 33 may calculate the average value of the tire pressure measurement data for one day, for example, and obtain a regression line for the average value calculated within a predetermined period by the least squares method. The change state calculation unit 33 is not limited to calculating the average value for one day, but may also calculate a median value as a representative value for one day by a known statistical method, and obtain a regression line for the representative value calculated within a predetermined period by the least squares method.

[0026] Furthermore, when the predetermined period is, for example, one month, the change state calculation unit 33 may create a population of tire pressures for each predetermined period and calculate the rate of change, or may create a population of measurement data for each day and calculate the rate of change. Furthermore, the change state calculation unit 33 may obtain a regression line by excluding local points showing maximum and minimum tire pressures in the distribution of measurement data within a predetermined period, for example.

[0027] Furthermore, the change state calculation unit 33 may set a plurality of predetermined periods and calculate the rate of change in tire pressure for each of the set predetermined periods. Considering that tire pressure fluctuates due to changes in the running state of the vehicle 7 and tire temperature, it is preferable to suppress the influence of fluctuations and grasp the overall trend of temporal change in tire pressure. The change state calculation unit 33 is useful for grasping short-term and long-term trends in the rate of change in tire pressure by setting a plurality of predetermined periods, for example, 5 days and 10 days.

[0028] The determination unit 34 reads out the rate of change in tire pressure calculated by the change state calculation unit 33 from the storage unit 37, and determines the occurrence of air loss in the tire 1 based on the rate of change in the tire pressure. Air loss in the tire 1 may occur gradually over a long period of time (e.g., several months) due to natural pressure reduction, or may occur suddenly in a short period of time (e.g., several minutes) due to a puncture, or may occur due to a condition known as a slow leak or slow puncture.

[0029] In terms of operational management of the vehicle 7, even if the tire body and wheels, etc. are properly manufactured within design tolerances and mounted on the vehicle 7, regular maintenance is performed to prevent air loss in the tire 1 due to natural pressure reduction that occurs over a period of approximately several months. Also, if the tire 1 is punctured and the air is suddenly lost in a short period of time (for example, within a few minutes), the driver will notice and immediately take measures such as changing the tire.

[0030] In contrast, the slow leak condition of tire 1 occurs when air leaks out faster than normal natural decompression, and is caused by misalignment when the tire body and wheel are assembled, as well as deterioration and installation problems of the rubber gasket and valve gasket in the valve.Slow leak conditions of tire 1 are also caused by mechanical damage (occurrence of cracks) and aging of the wheel, corrosion and rust of the wheel, distortion and deformation of the wheel, the presence of minute through holes due to manufacturing defects in the wheel, etc.

[0031] A slow puncture of a tire 1 is one in which air loss progresses faster than the slow leak described above, and occurs when a sharp foreign object such as a nail is stuck in the tire 1 and air gradually escapes. In a slow puncture, the tire 1 is kept airtight enough that air does not escape immediately when a foreign object is stuck in it, but due to the influence of vibrations caused by vehicle travel and temperature changes, a phenomenon occurs in which air gradually leaks from the point where the foreign object is stuck. Also, in a slow puncture, air escapes in a short period of time as the gap between the foreign object and the tire body widens or the foreign object is expelled.

[0032] If a tire 1 with a slow leak is mounted on a vehicle 7, the tire 1 will have to be frequently refilled with air in addition to regular maintenance, which will reduce transportation efficiency and increase maintenance costs in terms of operational management of the vehicle 7. Furthermore, if the vehicle 7 is operated with a tire 1 with a slow puncture mounted, there is a risk that the tire 1 will suddenly lose air.

[0033] The determination unit 34 compares the rate of change in tire pressure with a predetermined threshold, and determines that a slow leak or slow puncture has occurred if the rate of change is greater than the threshold. The determination unit 34 sets a first threshold and a second threshold greater than the first threshold as the predetermined threshold, and determines that a slow leak has occurred if the rate of change in tire pressure is greater than the first threshold and less than the second threshold. The determination unit 34 determines that a slow puncture has occurred if the rate of change is greater than the second threshold.

[0034] The determination unit 34 may make a judgment by comparing the rate of change in tire pressure with a predetermined threshold value for all tires 1 mounted on the vehicle 7. The determination unit 34 may also make a judgment by comparing the rate of change in tire pressure with a predetermined threshold value for the tire 1 having the largest rate of change in tire pressure among all tires 1 mounted on the vehicle 7.

[0035] The determination unit 34 outputs the determination result regarding the occurrence status of slow leak and slow puncture to the storage unit 37, and stores it as determination result information 37d in the storage unit 37. The determination result information 37d includes information indicating the occurrence status of slow leak and slow puncture, identification information of the corresponding vehicle 7, information on the mounting position of the determined tire 1 on the axle arrangement, date and time information, etc.

[0036] The notification unit 35 reads out the determination result information 37d from the storage unit 37, and generates alert information including information indicating the occurrence status of slow leaks and slow punctures, identification information of the corresponding vehicle 7, information on the mounting position of the determined tire 1 on the axle arrangement, date and time information, etc. The notification unit 35 notifies the generated alert information to the outside.

[0037] The notification unit 35 may output the alert information to a display unit 36 ​​included in the tire pressure monitoring device 30, display the alert information on the display unit 36, and notify the user. The display unit 36 ​​includes a display device such as a liquid crystal display, and displays the alert information input from the notification unit 35 on the display device.

[0038] The display unit 36 ​​may read out the measurement data of the tire pressure of the vehicle 7 corresponding to the alert information from the sensor measurement data 37b in the storage unit 37, and display it on the display device. The display unit 36 ​​displays the change in the tire pressure over a predetermined period (several months), for example, on the display device, thereby making the user aware of the change in the tire pressure.

[0039] The notification unit 35 may generate an e-mail including the generated alert information and send it to an e-mail address owned by the user. The user can receive the e-mail sent by the notification unit 35 and learn the alert information by using an application for sending and receiving e-mails in the tire pressure monitoring device 30 and the user terminal device 40. The user terminal device 40 is an information processing device such as a smartphone or a personal computer.

[0040] Next, the operation of the tire pressure monitoring system 100 will be described. FIG. 3 is a flowchart showing the procedure of the air loss determination process by the tire pressure monitoring system 100. An example of performing the determination process corresponding to a vehicle previously selected by the user will be described below, but the same process can be performed sequentially for multiple vehicles under operational management. The information acquisition unit 32 of the tire pressure monitoring device 30 acquires measurement data of tire pressure and tire temperature from the vehicle measurement device 20 (S1). The information acquisition unit 32 outputs the acquired measurement data of tire pressure and tire temperature to the memory unit 37 for storage.

[0041] The change state calculation unit 33 reads out the sensor measurement data 37b corresponding to the selected vehicle from the storage unit 37, and calculates the tire pressure change rate for all tires 1 mounted on the selected vehicle (S2). The change state calculation unit 33 stores the tire pressure change rate calculated in step S2 in the storage unit 37 as change state data 37c.

[0042] The determination unit 34 selects a tire 1 mounted on the vehicle and determines whether the rate of change in tire pressure is greater than a first threshold value (S3). If the determination is negative in step S3 (S3: NO), the determination unit 34 determines whether processing has been completed for all tires of the vehicle (S4). If the determination is negative in step S4 (S4: NO), the determination unit 34 selects the next tire (S5), returns to step S3, and repeats the processing.

[0043] If it is determined in step S3 that the rate of change in the tire pressure is greater than the first threshold (S3: YES), the determination unit 34 determines whether or not the rate of change in the tire pressure is greater than a second threshold (S6). If it is determined in step S6 that the rate of change is not greater than the second threshold (S6: NO), the determination unit 34 determines that the air loss occurring in the tire 1 is a slow leak (S7). After step S7, the determination unit 34 proceeds to step S4 and continues the process.

[0044] If it is determined in step S6 that the rate of change in tire pressure is greater than the second threshold value (S6: YES), the determination unit 34 determines that the air loss occurring in the tire 1 is a slow puncture (S8). After step S8, the determination unit 34 proceeds to step S4 to continue the process.

[0045] If it is determined in step S4 that the processing has been completed for all tires of the vehicle, the determination unit 34 outputs the determination results of steps S7 and S8 to the storage unit 37 for storage therein (S9), and ends the processing.

[0046] Fig. 4 is a graph showing an example of a tire pressure that is not determined to be a slow leak, and Fig. 5 is a graph showing an example of a tire pressure that is determined to be a slow leak. In Figs. 4 and 5, the horizontal axis represents time, and the vertical axis represents tire pressure. In the example shown in Figs. 4 and 5, for example, ten tires 1 are mounted on one truck vehicle, and the trend of tire pressure change over time in one of the ten tires 1 is roughly as shown in Fig. 5. The trend of tire pressure change over time in the other nine tires 1 out of the ten tires 1 is similar to that in Fig. 4.

[0047] Line segment A1 in Figure 4 represents a regression line with the specified period being one month from September 1st to September 30th, and the rate of change in tire pressure during this period is approximately 30 kPa / month. Converting the rate of change in tire pressure to a weekly rate is approximately 7 kPa / week. The tire pressure graph shown in Figure 4 shows that the rate of change in tire pressure is smaller than that in Figure 5, indicating a tendency for tire pressure to decrease naturally.

[0048] For example, the median tire pressure setting for the vehicle 7 is 950 kPa, the recommended lower limit is 850 kPa, and the threshold for warning that the tire pressure has dropped significantly and is approaching a dangerous range in terms of operational management is 800 kPa. For nine tires 1 with tire pressure changes over time equivalent to those shown in Fig. 4, operational management of the vehicle 7 can be performed by refilling air through regular maintenance, for example, every four to six months. In the example shown in Fig. 4, maintenance was performed to refill air into each tire 1 that was fitted to the vehicle in December.

[0049] Line segment A2 in Fig. 5 represents a regression line with the predetermined period being one month from September 1st to September 30th, and the rate of change in tire pressure during this period is approximately 50 kPa / month. Converting the rate of change in tire pressure to a weekly rate is approximately 12 kPa / week. The tire pressure graph shown in Fig. 5 shows a case where the rate of change in tire pressure is gentler than in the case of Fig. 4, and tire 1 is experiencing a slow leak.

[0050] The determination unit 34 of the tire pressure monitoring device 30 can determine that the air loss occurring in the tire 1 is a slow leak state by setting the first threshold value to 10 kPa / week.

[0051] According to the above-mentioned example of tire pressure setting, the tire pressure of one tire 1 shown in Fig. 5 becomes lower than the recommended lower limit of 850 kPa in September, and starts to fall below the threshold of 800 kPa at which a warning is issued in October. In terms of vehicle operation management, maintenance must be performed on the vehicle 7 in accordance with the tire 1 in a slow leak state, which increases the number of maintenance operations and reduces the operational efficiency of the vehicle. By determining that a slow leak is occurring, the determination unit 34 of the tire pressure monitoring device 30 can carry out maintenance such as replacement, inspection, and repair of the tire 1, thereby improving the operational efficiency of the vehicle.

[0052] FIG. 6 is a graph showing an example of tire pressures that are determined to be slow punctures. In FIG. 6, the horizontal axis represents time, and the vertical axis represents tire pressure. In the example shown in FIG. 6, for example, ten tires 1 are mounted on one truck vehicle, and the trend of tire pressure change over time in one of the ten tires 1 is roughly as shown in FIG. 6. The trend of tire pressure change over time in the other nine tires 1 out of the ten tires 1 is the same as that shown in the graph shown in FIG. 4, for example.

[0053] Line segment A3 in Fig. 6 represents a regression line with the predetermined period being one week from March 6 to March 13, and the rate of change in tire pressure during this period is approximately 30 kPa / week. The rate of change in tire pressure shown in Fig. 6 is greater than the rate of change in tire pressure of approximately 7 kPa / week for line segment A1 shown in Fig. 4 and the rate of change in tire pressure of approximately 12 kPa / week for line segment A2 shown in Fig. 5. In fact, tire 1, from which the tire pressure graph shown in Fig. 6 was obtained, saw a sudden decrease in tire pressure after March 21, resulting in a puncture.

[0054] By setting the second threshold to, for example, 25 kPa / week, the determination unit 34 of the tire pressure monitoring device 30 can determine that the air loss occurring in the tire 1 is a slow puncture. By determining that a slow leak is occurring, the determination unit 34 of the tire pressure monitoring device 30 can carry out maintenance such as replacement, inspection, and repair of the tire 1, thereby improving the operational efficiency of the vehicle.

[0055] In the tire pressure monitoring system 100, the information acquisition unit 32 acquires measurement data from air pressure sensors 11 provided on multiple tires 1 mounted on the vehicle 7, and the change state calculation unit 33 calculates the rate of change in the air pressure of each tire based on the measurement data. The determination unit 34 of the tire pressure monitoring system 100 determines the occurrence of air loss in the tires based on the rate of change calculated by the change state calculation unit 33. In this way, the tire pressure monitoring system 100 can monitor the state of air loss in the tires 1, and improve the maintainability of the tires 1.

[0056] Furthermore, the determination unit 34 of the tire pressure monitoring system 100 may determine the occurrence of air loss for the tire 1 with the largest rate of change calculated by the change state calculation unit 33. Considering that the multiple tires 1 mounted on the vehicle 7 have roughly the same quality, it is considered that each tire 1 will show roughly the same change in tire pressure due to the influence of the running state of the vehicle 7, tire temperature, etc. Therefore, a tire 1 with a significantly larger rate of change in tire pressure compared to other tires mounted on the vehicle 7 is assumed to be in a slow leak or slow puncture state. The tire pressure monitoring system 100 can assist in efficient maintenance of a tire 1 with a significant change in tire pressure among the multiple tires 1 mounted on the vehicle 7.

[0057] Furthermore, the determination unit 34 of the tire pressure monitoring system 100 compares the rate of change calculated by the change state calculation unit 33 with a predetermined threshold value to determine the occurrence of air loss in the tire 1. This enables the tire pressure monitoring system 100 to determine a threshold value based on previously acquired tire pressure measurement data and the occurrence of air loss in the tire 1, and to make a determination on the calculated rate of change in the tire pressure.

[0058] The tire pressure monitoring system 100 also includes at least one of a slow leak and a slow puncture as the occurrence state of air loss in the tire 1. This allows the tire pressure monitoring system 100 to determine the air loss state by targeting a slow leak and a slow puncture.

[0059] However, when the tire pressure monitoring system 100 judges that the tire 1 has a slow puncture, the tire 1 may be inspected to find that no part is judged to be punctured, and the tire 1 may have a significant defect in assembly accuracy and the slow leak may be significantly large. When the tire pressure monitoring system 100 judges that the tire 1 has a slow leak, the tire pressure monitoring system 100 may inspect the tire 1 to find that the cause cannot be identified. The tire pressure monitoring system 100 may judge that the tire 1 has a high possibility of being a slow leak or slow puncture, or that the tire 1 may be suspected of being a slow leak or slow puncture. In the present embodiment, an example has been described in which a slow puncture or slow leak is judged based on the rate of change in tire pressure. However, a slow puncture or slow leak may be judged when the change in tire pressure is in a predetermined pattern, or a slow puncture or slow leak may be judged based on a comparison between the rate of change in tire pressure over a long period of time and the rate of change in tire pressure over a short period of time for each tire of a vehicle.

[0060] The tire pressure monitoring system 100 determines the occurrence of air leakage corresponding to a slow leak or slow puncture by determining a predetermined period or threshold value based on the rate of change in tire pressure in past cases of slow leak, slow puncture, etc., thereby improving the maintainability of the tire 1.

[0061] Furthermore, the notification unit 35 of the tire pressure monitoring system 100 notifies the outside of the result determined by the determination unit 34. In this way, the tire pressure monitoring system 100 can inform the user or the like of the occurrence of deflation of the tire 1 mounted on the vehicle 7. In the case of a slow puncture, this notification may be to contact a service shop that can change the tire or the nearest emergency response organization (for example, within a 5 km radius) to the vehicle to request rescue.

[0062] (Modification) In the above-described embodiment, the determination unit 34 of the tire pressure monitoring system 100 determines whether air has leaked from the tire 1 by comparing the rate of change in tire pressure with a predetermined threshold value. The determination unit 34 may calculate the average value of the rates of change in tire pressure of the tire 1 with the maximum rate of change among the tires 1 mounted on the vehicle 7 and the other tires 1, and determine whether the ratio of the maximum rate of change to the average value is greater than a predetermined threshold value.

[0063] The judgment unit 34 may also calculate an average value M1 of the change rates of the tire air pressure of multiple tires 1 (e.g., two tires) selected from the tires 1 mounted on the vehicle 7 with the largest change rates, and an average value M2 of the change rates of the other tires 1, and judge whether the ratio of the average value M1 to the average value M2 is greater than a predetermined threshold value.

[0064] Regarding a slow leak, using the above example, it is assumed that the maximum rate of change in the tire 1 with a slow leak is about 12 kPa / week, and the average rate of change in the other tires 1 on the vehicle 7 is about 7 kPa / week. The determination unit 34 of the tire pressure monitoring system 100 can determine whether there is a slow leak by comparing the ratio of the maximum rate of change to the average rate of change with a threshold value (e.g., 1.5).

[0065] Also, regarding a slow puncture, using the above example, it is assumed that the maximum rate of change in the tire 1 with the slow puncture is about 30 kPa / week, and the average rate of change in the other tires 1 on the vehicle 7 is about 7 kPa / week. The determination unit 34 of the tire pressure monitoring system 100 can determine whether or not there is a slow puncture by comparing the ratio of the maximum rate of change to the average rate of change with a threshold value (e.g., 4).

[0066] The determination unit 34 of the tire pressure monitoring device 30 may determine the occurrence of air loss by comparing the decreasing trend of the air pressure in one tire 1 with the decreasing trend of the air pressure in the other tires 1 of the vehicle 7. One tire of the multiple tires 1 mounted on the vehicle 7 is designated as the "first tire 1" and the other tires are designated as the "second tires 1", and a first air pressure sensor 11 is attached to the first tire 1 and a second air pressure sensor 11 is attached to the second tire 1. Here, there are multiple second tires 1, and the second air pressure sensor 11 is provided for each second tire 1, and consists of multiple air pressure sensors 11.

[0067] The information acquisition unit 32 acquires measurement data of the first air pressure sensor 11 and the second air pressure sensor 11. The change state calculation unit 33 calculates the tendency of change in the tire air pressure measured by the first air pressure sensor 11 and the second air pressure sensor 11. The determination unit 34 determines the occurrence of air loss of the tire 1 (slow leak and slow puncture) based on the tendency of change in the tire air pressure calculated by the change state calculation unit 33. The first tire 1 is one of the multiple tires 1 mounted on the vehicle 7 that are selected in sequence, and the air pressure sensor 11 attached to the selected first tire is set as the first air pressure sensor 11. The second tire 1 is multiple tires 1 other than the selected first tire 1, and the air pressure sensors 11 attached to these tires 1 are set as the second air pressure sensor 11. The determination unit 34 sequentially determines the occurrence of air loss of the tire 1 based on the tendency of change in the tire air pressure in the first tire 1 and the multiple second tires 1 that are selected in sequence.

[0068] The change state calculation unit 33 calculates, for example, the rate of change in tire pressure for the selected first tire 1 and the multiple second tires 1. The determination unit 34 determines that air loss such as slow leak or slow puncture has occurred when the rate of change in tire pressure for the first tire 1 is greater than a predetermined threshold value and the rate of change in tire pressure for the second tire 1 is smaller than the threshold value. The tire pressure monitoring system 100 can assist in efficient maintenance of tires 1 that have a significant tendency for tire pressure changes among the multiple tires 1 mounted on the vehicle 7.

[0069] The change state calculation unit 33 and the judgment unit 34 may read out the sensor measurement data 37b obtained for multiple tires 1 mounted on the vehicle 7 from the memory unit 37, sequentially select one tire 1 to set it as first air pressure data for the first tire 1, and set the air pressure data for the other multiple second tires 1 as second air pressure data, calculate the trend of change in tire air pressure, and judge the occurrence status of air loss in the tire 1 based on the trend of change in tire air pressure.

[0070] In the above-described embodiment and modified examples, examples of each threshold value including the first threshold value and the second threshold value have been given, but the threshold values ​​are not limited to these and the numerical values ​​may be determined based on past cases or detailed design analysis of the tire 1.

[0071] The transportation business operator is not limited to a business that operates and manages trucks for transportation, but also includes, for example, a taxi business operator, etc. Furthermore, the vehicle 7 is not limited to a truck vehicle or a taxi vehicle, but also includes a rental vehicle provided by a rental business operator, a shared vehicle provided by a vehicle sharing business operator, a private car purchased by an ordinary household, etc.

[0072] The above description is based on the embodiments of the present invention. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

[0073] When the technical ideas embodied in the above-described embodiments and modified examples are generalized, it can be said that the technical ideas described in the following items are included.

[0074] The first item is a tire pressure monitoring system that includes an information acquisition unit that acquires measurement data from air pressure sensors installed in multiple tires mounted on a vehicle, a change state calculation unit that calculates the change state of the air pressure of each tire based on the measurement data acquired by the information acquisition unit, and a judgment unit that judges the occurrence of air loss in a tire based on the change state calculated by the change state calculation unit.

[0075] A second item is the tire pressure monitoring system according to the first item, in which the determination unit determines the occurrence state for a tire having the largest change state calculated by the change state calculation unit.

[0076] A third item is a tire pressure monitoring system described in any one of the first to second items, in which the judgment unit compares the change state calculated by the change state calculation unit with a predetermined threshold value to judge the occurrence status.

[0077] A fourth item is a tire pressure monitoring system according to any one of the first to third items, wherein the occurrence condition includes at least one of a slow leak and a slow puncture.

[0078] A fifth item is the tire pressure monitoring system according to any one of the first to fourth items, further comprising a notification unit that notifies an outside of a result determined by the determination unit.

[0079] The sixth item is a tire pressure monitoring method including an information acquisition step of acquiring measurement data from air pressure sensors provided on multiple tires mounted on a vehicle, a change state calculation step of calculating a change state of the air pressure of each tire based on the measurement data acquired by the information acquisition step, and a determination step of determining whether air loss has occurred in a tire based on the change state calculated by the change state calculation step.

[0080] The seventh item is a tire pressure monitoring system comprising: a first air pressure sensor provided on a first tire among a plurality of tires mounted on a vehicle; a second air pressure sensor provided on a second tire other than the first tire; an information acquisition unit that acquires measurement data from the first air pressure sensor and the second air pressure sensor; a change state calculation unit that calculates the air pressure trend of each tire based on the measurement data acquired by the information acquisition unit; and a determination unit that determines the occurrence of air loss in a tire based on the tire air pressure trend (change trend) measured by the first air pressure sensor and the second air pressure sensor. [Explanation of symbols]

[0081] 1 tire, 7 vehicle, 11 air pressure sensor, 32 information acquisition unit, 33 change state calculation unit, 34 determination unit, 35 notification unit, 100 Tire Pressure Monitoring System.

Claims

1. an information acquisition unit that acquires measurement data from air pressure sensors provided in a plurality of tires mounted on a vehicle; a change state calculation unit that calculates a change state of the air pressure of each tire based on the measurement data acquired by the information acquisition unit; a determination unit that determines whether air has leaked from a tire based on the state of change calculated by the state of change calculation unit; A tire pressure monitoring system comprising:

2. 2. The tire pressure monitoring system according to claim 1, wherein the determination unit determines the occurrence state for a tire whose state of change calculated by the state-of-change calculation unit is the largest.

3. 2. The tire pressure monitoring system according to claim 1, wherein the determination unit compares the change state calculated by the change state calculation unit with a predetermined threshold value to determine the occurrence state.

4. The tire pressure monitoring system according to claim 1 , wherein the occurrence condition includes at least one of a slow leak and a slow puncture.

5. The tire pressure monitoring system according to claim 1 , further comprising a notification unit that notifies an external device of the result of the determination made by the determination unit.

6. An information acquisition step of acquiring measurement data by air pressure sensors provided on a plurality of tires mounted on a vehicle; a change state calculation step of calculating a change state of the air pressure of each tire based on the measurement data acquired in the information acquisition step; a determination step of determining whether or not air has leaked from a tire based on the state of change calculated in the state of change calculation step; A tire pressure monitoring method comprising:

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