Air pressure management device and air pressure management method

Abstract

Provided are an air pressure management device and an air pressure management method capable of accurately determining the presence or absence of an abnormality in the air pressure of a tire and the abnormality type. A cloud server 30 serving as an air pressure management device includes an abnormality determining unit 36 that determines the presence or absence of an abnormality in a tire 2 and the type of the abnormality on the basis of the comparison result between a reference air pressure and a temperature-converted air pressure, wherein the abnormality determining unit 36 includes: a first abnormality determining unit 36A which determines that there is an abnormality in the tire 2 if a difference value between the reference air pressure and the temperature-converted air pressure is equal to or greater than a first threshold K1, and determines that the type of the abnormality is a puncture of the tire 2 if the difference value is equal to or greater than a second threshold K2 larger than the first threshold; and a second abnormality determining unit 36B which determines whether the type of the abnormality is a slow leak or natural leakage of the tire 2 if the difference value is equal to or greater than the first threshold K1 and smaller than the second threshold K2.

Description

Air pressure control device and air pressure control method

[0001] The present invention relates to an air pressure control device and an air pressure control method for controlling the air pressure of a tire.

[0002] Properly managing the air pressure of tires mounted on a vehicle ensures the vehicle's driving stability. In recent years, attempts have been made to install TPMS (Tire Pressure Monitoring System) sensors in tires and manage air pressure information obtained from the TPMS sensors via the cloud (see, for example, Patent Document 1). With this type of technology, if the air pressure of a tire drops below a given threshold, the driver or vehicle manager is notified of the air pressure abnormality, allowing tire maintenance work to be performed promptly.

[0003] Japanese Patent Application Laid-Open No. 2021-046160

[0004] Incidentally, this type of air pressure abnormality includes a so-called puncture, which is a sudden drop in air pressure over a short period of time, such as a few minutes to a few tens of minutes, a so-called slow leak, which is a gradual drop in air pressure over a period of a few hours to a few days, and a so-called natural leak, which is a gradual drop in air pressure over a long period of time, such as one month to several months. When an air pressure abnormality occurs, maintenance work can be performed by simply refilling the tire with air if the air pressure is a natural leak, but in the case of a slow leak or a puncture, the valve must be inspected or the tire must be removed from the rim for inspection. As such, the maintenance work required varies depending on the type of air pressure abnormality, and accurate determination of the cause of the air pressure abnormality is required. However, accurately determining the cause of these air pressure abnormalities is difficult, leaving room for improvement.

[0005] The present invention has been made in consideration of the above, and aims to provide an air pressure management device and an air pressure management method that can accurately determine the cause of abnormal tire air pressure and reduce tire maintenance work.

[0006] In order to solve the above-mentioned problems and achieve the object, the air pressure management device of the present invention comprises an information acquisition unit that acquires sensor information including the air pressure and temperature of a tire mounted on a vehicle at a predetermined timing; a reference information setting unit that sets reference information including a reference air pressure and reference temperature of the tire; a temperature-converted air pressure calculation unit that calculates the temperature-converted air pressure of the tire at the reference temperature based on the sensor information and the reference information; and an abnormality determination unit that determines the presence or absence of a tire abnormality and the type of the abnormality based on a comparison result between the reference air pressure and the temperature-converted air pressure.The abnormality determination unit comprises a first abnormality determination unit that determines that there is an abnormality in the tire if the difference value between the reference air pressure and the temperature-converted air pressure is equal to or greater than a first threshold, and that determines the type of abnormality to be a tire puncture if the difference value is equal to or greater than a second threshold that is greater than the first threshold, and a second abnormality determination unit that determines the type of abnormality to be either a slow tire leak or a spontaneous tire leak if the difference value is equal to or greater than the first threshold but less than the second threshold.

[0007] The air pressure management method of the present invention comprises the steps of: acquiring sensor information including the air pressure and temperature of a tire mounted on a vehicle at a predetermined timing; setting reference information including a reference air pressure and reference temperature of the tire; calculating the temperature-converted air pressure of the tire at the reference temperature based on the sensor information and the reference information; and determining the presence or absence of a tire abnormality and the type of the abnormality based on the results of comparing the reference air pressure with the temperature-converted air pressure.In the step of determining the presence or absence of a tire abnormality and the type of the abnormality, if the difference value between the reference air pressure and the temperature-converted air pressure is equal to or greater than a first threshold, it is determined that there is an abnormality in the tire, and if the difference value is equal to or greater than a second threshold that is greater than the first threshold, it is determined that the type of abnormality is a tire puncture.If the difference value is equal to or greater than the first threshold but less than the second threshold, it is determined that the type of abnormality is either a slow tire leak or a natural tire leak.

[0008] According to the present invention, the cause of abnormal tire air pressure can be determined with high accuracy, thereby realizing a reduction in tire maintenance work.

[0009] FIG. 1 is a block diagram showing the overall configuration of an air pressure management system including an air pressure management device according to a first embodiment. FIG. 2 is a block diagram showing the functional configuration of a cloud server of the air pressure management system. FIG. 3 is a graph showing the relationship between the ratio of the inner surface area and inner volume of a tire and the monthly natural leakage rate. FIG. 4 is a flowchart showing the operation procedure of the air pressure management system. FIG. 5 is a flowchart showing the operation procedure of a puncture detection process. FIG. 6 is a flowchart showing the operation procedure of a puncture detection process according to a second embodiment. FIG. 7 is a graph showing the temperature-converted air pressure and temperature of a tire over time. FIG. 8 is a block diagram showing the functional configuration of a cloud server according to a third embodiment.

[0010] Hereinafter, an embodiment of an air pressure management device according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the components in this embodiment include those that are replaceable and easily conceivable by a person skilled in the art, or those that are substantially the same.

[0011] The air pressure management device according to this embodiment centrally manages the air pressure of tires (pneumatic tires) mounted on multiple vehicles. Specifically, the air pressure management device is suitable for centrally managing the air pressure of tires mounted on multiple vehicles owned by a business entity, such as taxis, or multiple shared vehicles owned by a business entity and shared by multiple users, such as in car sharing or rental cars. This embodiment will be described taking as an example a case in which the air pressure management device is used in a car sharing business.

[0012] A car sharing business is a service in which shared vehicles are rented to pre-registered users and shared among the users. In a car sharing business, multiple shared vehicles are parked in parking areas called stations. The number of shared vehicles parked at these stations and the number of stations scattered within a specified area are determined appropriately depending on the scale of the business, etc. When a user uses a shared vehicle, the station serves as the departure and return point for the shared vehicle. In this embodiment, for example, when a shared vehicle is returned to a station, the tire pressure management device determines whether or not there is an abnormality in the tire pressure of the shared vehicle and the type of abnormality. If an abnormality in tire pressure occurs, the tire pressure management device notifies the vehicle manager who manages the relevant shared vehicle or station.

[0013] [First Embodiment] Fig. 1 is a block diagram showing the overall configuration of a tire pressure management system including an air pressure management device according to a first embodiment. Fig. 2 is a block diagram showing the functional configuration of a cloud server of the tire pressure management system. As shown in Fig. 1, the tire pressure management system 100 includes sensors 3 provided on tires 2 of multiple shared vehicles (vehicles) 1, a sensor receiving terminal 10 installed at a station where the multiple shared vehicles 1 are parked, an administrator terminal 20 that manages the station, and a cloud server (air pressure management device) 30.

[0014] The sensor receiving terminal 10, the administrator terminal 20, and the cloud server 30 are communicatively connected via a communication network 50, such as the Internet. The cloud server 30 is also communicatively connected via the communication network 50 to a car sharing management server (not shown) owned by a car sharing business entity. The car sharing management server accepts user reservations for use of multiple shared vehicles and creates usage schedule information for the reserved shared vehicles. This usage schedule information includes vehicle information for the shared vehicle 1, user information, the start time and end time of use, and information about the stations that are the departure and return locations. For convenience, the example in FIG. 1 shows one shared vehicle 1, one sensor receiving terminal 10, and one administrator terminal 20, but in reality, multiple shared vehicles 1, one sensor receiving terminal 10, and one administrator terminal 20 are provided.

[0015] The sensor 3 has at least a tire pressure monitoring system (TPMS) function and is configured with an air pressure sensor 3a that detects the air pressure of the tire 2 and a temperature sensor 3b that detects the temperature of the air inside the tire 2. The sensor 3 may also be configured with an acceleration sensor that detects centrifugal acceleration acting on the tire 2. To achieve additional detection functions such as wear detection, road surface detection, fault detection, and loosening of mounting bolts, the sensor 3 may also be configured with appropriate additional sensors such as piezoelectric sensors, capacitance sensors, magnetic sensors, and MEMS microphone sensors. The sensors 3 are each attached to the inner surface of the tire 2. Therefore, the sensors 3 are less susceptible to the environment outside the tire 2, and can easily detect the air pressure and temperature of the tire 2 with a simple configuration, such as by replacing the tire 2 with a tire 2 equipped with a sensor 3. Each sensor 3 is assigned a sensor ID (identification information), and the correspondence between the sensor ID of the sensor 3 and the wheel position (left front wheel, right front wheel, left rear wheel, or right rear wheel) of the tire 2 equipped with the sensor 3 is registered in the sensor receiving terminal 10. The sensor 3 includes a battery as a power source. For example, while the shared vehicle 1 is parked at a station, the sensor 3 detects tire pressure and temperature data (sensor information) every predetermined time (e.g., every three minutes) and transmits the detected data to the sensor receiving terminal 10 along with a sensor ID (identification information). This configuration makes it possible to detect changes (reductions) in tire pressure in the tires 2 after the shared vehicle 1 is returned to the predetermined station (e.g., during the nighttime). The battery life of the sensor 3 is set to be longer than the typical service life of a tire 2. Data can be transmitted from the sensor 3 to the sensor receiving terminal 10 using short-range wireless communication such as RF (radio frequency) communication. Note that the data detected by each sensor 3 is stored in a predetermined memory unit and may be transmitted to the sensor receiving terminal 10 using the short-range wireless communication described above, for example, while the shared vehicle 1 is parked at the station.

[0016] In addition to the sensor 3 described above, the shared vehicle 1 may also be provided with various sensors for detecting vehicle information (e.g., a GNSS (Global Navigation Satellite System) receiving sensor for receiving GNSS signals, an engine operation detection sensor for detecting engine on / off, and a vehicle speed pulse detection sensor). These sensors can be used, for example, to calculate the vehicle's operating rate (e.g., the percentage of driving time per day). In the present embodiment, the sensor 3 is configured to directly detect the air pressure and temperature of the tire 2. However, the temperature is not limited to the temperature inside the tire. A sensor for detecting the outside air temperature may also be provided in the vehicle. Instead of directly measuring the air pressure, table data showing the relationship between the air pressure and a physical quantity (e.g., wheel rotation speed) correlated with the air pressure may be prepared in advance, and the air pressure may be obtained from the detected physical quantity and the table data. This configuration can be used to simply manage the air pressure of the tire 2, even in a configuration in which the tire 2 does not have a TPMS sensor (sensor 3).

[0017] The sensor receiving terminal 10 is installed at a station where the shared vehicles 1 are parked. As shown in FIG. 1 , the sensor receiving terminal 10 includes a sensor receiving unit 11, a storage unit 12, a communication unit 13, and a control unit 14. The sensor receiving unit 11 receives data transmitted from the sensors 3 of the four tires 2 of each shared vehicle 1. The sensor receiving unit 11 also receives data transmitted from various sensors mounted on the vehicle. The storage unit 12 is configured with storage means such as volatile or non-volatile memory or an HDD. The storage unit 12 stores various programs executed by the control unit 14 and various data. In this embodiment, the storage unit 12 determines the corresponding shared vehicle 1 and wheel position from the sensor ID of the data received by the sensor receiving unit 11 at predetermined time intervals, and stores the air pressure and temperature (including correlated physical quantities and temperatures) of each tire 2 included in the received data as historical information on the air pressure and temperature of the tire at each wheel position of the corresponding shared vehicle 1. The storage unit 12 may store and update the air pressure and temperature of each tire 2 for a predetermined period (for example, the last six months). When the tires 2 are rotated in the shared vehicle 1, the correspondence between the sensor ID registered in the sensor receiving terminal 10 and the wheel position is corrected. The storage unit 12 also stores data related to the vehicle's operating status, etc., received by the sensor receiving unit 11 at predetermined time intervals, as historical information on the operating status of the shared vehicle 1.

[0018] The communication unit 13 is configured to be able to wirelessly communicate with the cloud server 30 via the communication network 50. The communication unit 13 transmits air pressure information of the tires 2 mounted on the shared vehicle 1 along with the vehicle ID of the shared vehicle 1 to the cloud server 30 at predetermined time intervals. Specifically, the communication unit 13 transmits air pressure information including the air pressure and temperature (including correlated physical quantities and temperatures) of the tires 2 of each shared vehicle 1 corresponding to the sensor ID to the cloud server 30. The communication unit 13 also transmits historical information on the operating status of each shared vehicle 1 to the cloud server 30.

[0019] The control unit 14 has a CPU and performs predetermined processing based on the received air pressure information of each tire 2 of each shared vehicle 1, data related to the operating status of the vehicle, or data stored in the memory unit 12.

[0020] The cloud server 30 centrally manages the air pressures of the tires 2 of multiple shared vehicles 1. The cloud server 30 acquires and stores air pressure information and the like of each tire 2 of the shared vehicles 1 transmitted from the sensor receiving terminal 10, and determines whether or not there is an air pressure abnormality in each tire 2 and the type of abnormality. Furthermore, when the cloud server 30 determines that there is an air pressure abnormality in a tire 2, it transmits the point at which the air pressure abnormality occurred and the type of abnormality to the administrator terminal 20 that manages the station of the shared vehicle 1 on which the tire 2 is mounted.

[0021] The cloud server 30 is configured by, for example, a computer installed in the cloud, etc. As shown in Fig. 2 , the cloud server 30 includes a communication unit 31, an information acquisition unit 32, a reference information setting unit 33, a temperature-converted air pressure calculation unit 34, an average value calculation unit 35, an abnormality determination unit 36, a natural leakage air pressure estimation unit 37, a natural leakage threshold setting unit 38, a memory unit 39, and a control unit 40.

[0022] The communication unit 31 is configured to be able to wirelessly communicate with the sensor receiving terminal 10 and the manager terminal 20 via the communication network 50. The communication unit 31 receives each piece of data (sensor information) of the shared vehicle 1 and the tire 2 transmitted from the sensor receiving terminal 10. Furthermore, if an abnormality in the air pressure of a tire 2 occurs, the communication unit 31 transmits information such as the fact that the air pressure abnormality has occurred and the type of air pressure abnormality to the manager terminal 20 that manages the station where the corresponding shared vehicle 1 is parked.

[0023] The information acquisition unit 32 acquires vehicle information of the shared vehicle 1 (e.g., sensor information related to the vehicle's operating status, etc.) and air pressure information (sensor information) of each tire 2 of the shared vehicle 1 at a predetermined timing received from the sensor receiving terminal 10 via the communication unit 31. This predetermined timing can be set as appropriate, but for example, air pressure information of each tire 2 collected by the sensor receiving terminal 10 may be acquired every predetermined time period (e.g., every three hours) in order to accurately determine whether or not there is an air pressure abnormality in each tire 2. This air pressure information includes the vehicle ID of the shared vehicle 1, the sensor ID of each sensor 3, the correspondence between the sensor ID and the wheel position, and the air pressure (or a physical quantity related to the air pressure) and temperature (or an outside air temperature related to the tire temperature) of each tire 2 detected by each sensor 3.

[0024] The reference information setting unit 33 sets reference information including a reference air pressure and a reference temperature of the tire 2. This reference information serves as a basis for determining whether or not there is an air pressure abnormality in the tire 2 and the type of abnormality. The reference information may be, for example, a fixed value or a value that varies depending on a certain parameter. In this embodiment, the reference information setting unit 33 sets an initial value as the reference air pressure by updating it as needed based on an average value of the temperature-converted air pressure over a predetermined period, which will be described later.

[0025] Under the control of the control unit 40, the temperature-converted air pressure calculation unit 34 calculates a temperature-converted air pressure, which is calculated by converting the air pressure at a reference temperature based on the acquired air pressure information (sensor information) and the set reference information. Generally, the air pressure of the tire 2 tends to change depending on the air temperature. Therefore, the air pressure may differ between when the vehicle is in motion and when it is stopped, making it difficult to accurately manage the air pressure fluctuations. For this reason, the temperature-converted air pressure calculation unit 34 converts the air pressure of the tire 2 to the air pressure at the reference temperature (e.g., 20°C) based on, for example, the Boyle-Charles law. This allows for consideration of air pressure fluctuations due to temperature changes in the tire 2. In other words, it is possible to correct for external fluctuation factors (air pressure fluctuations due to temperature changes), thereby enabling more accurate management of air pressure changes.

[0026] The average value calculation unit 35 calculates the average value of the temperature-converted air pressure over a predetermined period of time. Specifically, it calculates the average value of the temperature-converted air pressure over a predetermined period of time in the past (e.g., the last 10 days) for the same tire 2. Although external factors such as changes in the weight of the shared vehicle 1 (number of passengers and luggage) and changes in outside temperature due to seasonal fluctuations can also cause changes in the air pressure of the tire 2, this configuration makes it possible to set an appropriate reference air pressure that suppresses the influence of these external factors by updating the reference air pressure with the average value of the temperature-converted air pressure, thereby making it possible to accurately determine whether or not there is an abnormality in the air pressure of the tire 2.

[0027] The abnormality determination unit 36 ​​determines the presence or absence of an abnormality in the tire 2 and the type of abnormality based on the comparison result between the calculated temperature-converted air pressure and the set reference air pressure. In this case, the abnormality in the tire 2 is primarily an air pressure abnormality. Furthermore, the type of abnormality in the tire 2 primarily refers to a state of air pressure loss, such as a puncture resulting in an air pressure loss of 50 kPa or more per minute, a slow leak resulting in an air pressure loss of approximately 5 to 20 kPa per day, or a natural leak resulting in an air pressure loss of approximately several kPa to 30 kPa per month. Generally, a slow leak causes a faster air pressure loss rate than a natural leak, but a slower air pressure loss rate than a normal puncture. For this reason, it is difficult for a driver to notice the occurrence of a slow leak. In particular, in a shared vehicle 1 for car sharing, since the user (driver) does not drive the shared vehicle 1 on a daily basis, it is difficult for the user (driver) to notice a slow leak even if the air pressure is decreasing. On the other hand, if a slow leak progresses and the air pressure falls below a predetermined reference value, driving safety is compromised. Furthermore, if there is a natural leak, the tire 2 can usually be restored to the appropriate air pressure by refilling it with air, but a slow leak is a type of puncture, and therefore requires, for example, removing the tire from the rim and repairing or replacing it. For this reason, it is desirable to accurately distinguish between natural leaks and slow leaks and to quickly determine whether a slow leak is present. In this embodiment, when an air pressure abnormality occurs in the tire 2, the abnormality determination unit 36 ​​can appropriately determine whether the abnormality is a puncture, a slow leak, or a natural leak.

[0028] The abnormality determination unit 36 ​​includes a first abnormality determination unit 36A that, when an air pressure abnormality occurs in the tire 2, determines that the type of abnormality is a puncture of the tire 2, and a second abnormality determination unit 36B that determines whether the type of abnormality is a slow leak or a spontaneous leak of the tire 2. Specifically, the first abnormality determination unit 36A determines that there is an abnormality in the tire 2 when the difference value between the reference air pressure and the temperature-converted air pressure is equal to or greater than a first threshold value K1. Furthermore, the first abnormality determination unit 36A determines that the type of abnormality is a normal puncture of the tire 2 when the difference value is equal to or greater than a second threshold value K2 that is greater than the first threshold value K1.

[0029] The first threshold value K1 is a threshold value at which at least a natural leak from the tire 2 is estimated, and the second threshold value K2 is a threshold value at which a puncture of the tire 2 is estimated. These threshold values ​​K1 and K2 are numerical values ​​determined according to, for example, the "maximum air pressure" specified by JATMA. In this embodiment, assuming that the maximum air pressure of the tire 2 is 240 kPa, the first threshold value K1 is set to approximately 3% (8 kPa) of the maximum air pressure. The first threshold value K1 is preferably set to 2 to 5% of the maximum air pressure. The second threshold value K2 is set to approximately 20% (50 kPa) of the maximum air pressure. The second threshold value K2 is preferably set to 15 to 25% of the maximum air pressure. In this way, the first abnormality determination unit 36A can appropriately determine a puncture of the tire 2 by determining the type of air pressure abnormality using two threshold values.

[0030] On the other hand, when an air pressure abnormality occurs in the tire 2, the second abnormality determination unit 36B determines whether the type of abnormality is a slow leak or a spontaneous leak. Specifically, when the above-mentioned difference value is equal to or greater than the first threshold value K1 and smaller than the second threshold value K2, the second abnormality determination unit 36B compares this difference value with a set spontaneous leak threshold value K3. Then, when the difference value is equal to or smaller than the spontaneous leak threshold value K3, the second abnormality determination unit 36B determines the type of abnormality to be a spontaneous leak, and when the difference value is greater than the spontaneous leak threshold value K3, the second abnormality determination unit 36B determines the type of abnormality to be a slow leak.

[0031] The natural leakage threshold K3 is a threshold for distinguishing between natural leakage and slow leakage of the tire 2, and is set based on the natural leakage air pressure estimated to occur from the tire 2 in a predetermined unit period (e.g., one month). Specifically, if the natural leakage air pressure that will occur from the tire 2 with an initial air pressure immediately after filling (e.g., maximum air pressure (240 kPa)) in one month is estimated to be, for example, 6% (14 kPa), the natural leakage threshold K3 is set to 6% (14 kPa). The natural leakage threshold K3 is set to a value that is greater than the first threshold K1 and less than the second threshold K2. In this embodiment, the unit period is set to one month, but the natural leakage threshold K3 may be changed as appropriate as long as the condition that the natural leakage threshold K3 is greater than the first threshold K1 and less than the second threshold K2 is satisfied.

[0032] The natural leakage pressure estimation unit 37 estimates the air pressure (natural leakage pressure) that decreases due to natural leakage from the tire 2 over a predetermined unit period (e.g., one month). It is generally known that the gas permeability of the rubber material that constitutes the tire 2 is temperature-dependent. In particular, the gas permeability of the inner liner, which contributes greatly to the natural leakage rate of the tire 2, is known to correlate with the Arrhenius plot. Furthermore, because the tire 2 is made of a viscoelastic material, it generates heat while traveling, causing the temperature inside the tire 2 to rise. For this reason, the amount of natural leakage from the tire 2 is greater in a dynamic (moving) state than in a static (stationary) state, and the static natural leakage rate and the dynamic natural leakage rate can differ by several to ten times. In this embodiment, the natural leakage pressure estimation unit 37 estimates the natural leakage pressure based on the operating rate of the shared vehicle 1.

[0033] Specifically, for example, if the average stop time of the shared vehicle 1 in one day (24 hours) is T2, the average operating time T1 can be expressed as T1 = 24 - T2. This operating status (average operating time T1 and average stop time T2) can be obtained from sensor information (e.g., GNSS information, engine on / off information, vehicle speed pulse information, etc.) acquired by the information acquisition unit 32. Furthermore, if the static leakage rate of the tire 2 is ALs (% / month), the dynamic leakage rate is ALd (% / month), and the initial air pressure is P0 (kPa), the natural leakage air pressure ALtp leaking in one month (30 days) can be calculated using the following formula (1): where α and β are correction coefficients that can be adjusted as appropriate based on tire structural factors that affect the natural leakage rate, such as the material and gauge of the inner liner, the number of belts, and the number of carcasses. For example, if the inner liner material is changed to a material that is twice as leak-resistant as the conventional material, and the contribution of the inner liner to the static and dynamic leakage rates is assumed to be 40%, α and β can be set to 0.8. Also, different values ​​can be used for α and β, and the correction coefficients can be obtained from the results of actual measurements.

[0034] ALtp=P0×{α×ALs×((T1 / 24)÷30)+β×ALd×((T2 / 24)÷30)} (1)

[0035] In this way, the natural leakage air pressure estimation unit 37 can accurately estimate the natural leakage air pressure because it calculates the natural leakage air pressure for a predetermined unit period by allocating the ratio according to the static and dynamic operating conditions of the shared vehicle 1. Note that the static leakage rate ALs and the dynamic leakage rate ALd described above each have temperature dependency, and therefore may be corrected by temperature.

[0036] In this embodiment, the natural leakage pressure estimation unit 37 is configured to estimate the natural leakage pressure based on the operating rate of the shared vehicle 1, but other methods may be used to estimate the natural leakage pressure. Specifically, the natural leakage pressure estimation unit 37 estimates the natural leakage pressure using a relational expression that indicates the relationship between the ratio A / V of the inner surface area A and the inner volume V of the tire 2 and the natural leakage pressure leaking in a predetermined unit period (one month). Figure 3 is a graph showing the relationship between the ratio of the inner surface area and the inner volume of the tire and the natural leakage rate.

[0037] The graph shown in Figure 3 shows the relationship between the ratio A / V (A / Vo) of a plurality of tires of a representative size (nominal width: 175-225, inch: 14-16) and the monthly natural leakage rate of the tire, measured for each tire. While it is possible to measure and map the static and dynamic natural leakage rates of all tire sizes in advance, this would require a huge amount of testing time. Therefore, in this embodiment, a relationship equation (regression equation) derived from the ratio A / V and natural leakage rate of a reference tire of a representative size is used to derive an estimated natural leakage rate for that tire from the ratio A / V of the relevant tire, thereby achieving both reduced testing efficiency and improved prediction accuracy.

[0038] The inner surface area A is the surface area (mm ２ ) and the internal volume V is the volume of the internal space (mm ３ ) The inner surface area A and the internal volume V are based on the values ​​when the target tire is mounted on a measurement rim. On the other hand, if the mounting rim is predetermined, the values ​​when the tire is mounted on that rim may be used. The inner surface area A and the internal volume V may be calculated from, for example, values ​​on a computer-aided design (CAD) drawing of the tire, or from a computed tomography (CT) image of the tire taken under no-load conditions after inflating the tire to the vehicle's specified air pressure. Furthermore, detailed tire information may include tire structure information such as tire size, mounting position, reference inner surface area, reference internal volume, inner liner gauge, number of carcasses, carcass TUH, and number of belts. For example, the inner liner gauge can be substituted for the minimum inner liner gauge in the center of the tire. However, the accuracy of the inner surface area A and the internal volume V can be improved by measuring five or more points at equal intervals in the periphery and using the average value.

[0039] In this embodiment, the natural leakage air pressure estimation unit 37 can easily and accurately estimate the natural leakage air pressure using a relational expression that shows the relationship between the ratio A / V of the inner surface area A and the inner volume V of the tire 2 and the natural leakage rate of leakage in a predetermined unit period (one month). As shown in Fig. 3, for example, when the ratio A / V of the inner surface area A and the inner volume V is 0.025, the natural leakage rate is 4.25 (% / month), and when the reference initial set air pressure is 240 kPa, the natural leakage rate decreases by approximately 10 kPa after the unit period (one month).

[0040] The natural leakage threshold setting unit 38 sets the natural leakage threshold K3 based on the natural leakage air pressure estimated by the natural leakage air pressure estimation unit 37. The natural leakage threshold setting unit 38 sets the natural leakage threshold K3 based on the natural leakage rate (% / month) estimated to occur in, for example, one month. Specifically, if the initial filling air pressure (maximum air pressure) is 240 kPa and the natural leakage rate is estimated to be 6% (14 kPa), the natural leakage threshold setting unit 38 sets this 6% (14 kPa) as the natural leakage threshold K3.

[0041] The storage unit 39 is configured to include storage means such as a volatile or non-volatile memory or an HDD. The storage unit 39 stores various programs executed by the control unit 40 and various calculated data. The storage unit 39 stores, as history information, the air pressure information acquired by the information acquisition unit 32 at predetermined time intervals for each vehicle ID (shared vehicle 1), including the air pressure and temperature of the tire 2 at the wheel position corresponding to the sensor ID. Furthermore, when air pressure maintenance is performed on the target shared vehicle 1, the storage unit 39 records this maintenance history information.

[0042] The control unit 40 has a CPU and performs predetermined processing based on information received from the sensor receiving terminal 10, the administrator terminal 20, and the car sharing management server via the communication unit 31, or on data stored in the memory unit 39. Furthermore, if the control unit 40 determines that the abnormal air pressure of the target shared vehicle 1 is a flat tire, it outputs a signal to the administrator terminal 20 of the station for this shared vehicle 1 and the car sharing management server that a flat tire has occurred in the tire 2 of the shared vehicle 1. In this case, the car sharing management server checks whether a reservation for use of the shared vehicle 1 has been made on that day, and if so, transfers the reservation to another shared vehicle 1 of the same class and notifies the user of this fact. Meanwhile, the station that has been notified of the flat tire via the administrator terminal 20 performs maintenance (puncture repair) on the tire 2 of the shared vehicle 1.

[0043] Furthermore, if the control unit 40 determines that the air pressure abnormality of the target shared vehicle 1 is a slow leak, it outputs to the administrator terminal 20 of the station for the shared vehicle 1 and the car sharing management server that a slow leak has occurred in the tire 2 of the shared vehicle 1. Generally, a slow leak is not severe enough to immediately halt use of the shared vehicle 1. For this reason, if a reservation for use of the shared vehicle 1 has been made for that day, the car sharing management server notifies the user to request that the shared vehicle 1 be replenished with air. If the user performs an air replenishment, a discount coupon for the usage fee may be sent, for example. For example, if air pressure information from the sensor 3 confirms that air has been replenished, the discount coupon may be automatically sent. Meanwhile, if the station is notified of the occurrence of a slow leak via the administrator terminal 20 and there is no reservation for use of the shared vehicle 1, maintenance of the tire 2 (such as refilling with air, checking for damage to the tire, air valve, wheel, etc., and repairing a puncture) is performed.

[0044] Furthermore, if the control unit 40 determines that the abnormal air pressure of the target shared vehicle 1 is a natural leak, it outputs to the administrator terminal 20 of the station for the shared vehicle 1 and to the car sharing management server that a natural leak has occurred in the tire 2 of the shared vehicle 1. Generally, a natural leak occurs during normal use and does not result in the suspension of use of the shared vehicle 1. For this reason, if a reservation for use of the shared vehicle 1 has been made for that day, the car sharing management server notifies the user to request that the shared vehicle 1 be replenished with air. If the user performs the air replenishment, the car sharing management server may send, for example, a discount coupon for the usage fee. Meanwhile, the station that has been notified of the natural leak via the administrator terminal 20 performs maintenance on the tire 2 (such as refilling with air or checking for damage to the tire, air valve, wheel, etc.) if there is no reservation for use of the shared vehicle 1.

[0045] The manager terminal 20 is a terminal device installed at a station where a shared vehicle 1 is parked. As shown in FIG. 1 , the manager terminal 20 includes a communication unit 21, a memory unit 22, a display unit 23, an input unit 24, a notification unit 25, and a control unit 26. The communication unit 21 is configured to be able to wirelessly communicate with the cloud server 30 via a communication network 50. The communication unit 21 receives information from the cloud server 30 regarding the presence or absence of an air pressure abnormality in the target shared vehicle 1 and the type of air pressure abnormality. Furthermore, when a station worker inputs a request to refill the tires 2 of the shared vehicle 1 with air or repair a puncture, the communication unit 21 transmits maintenance completion information to the cloud server 30 along with the vehicle ID of the shared vehicle 1. Here, upon receiving the maintenance completion information, the cloud server 30 transmits a maintenance completion report to the car sharing management server. This makes it possible to sequentially accept new usage reservations for shared vehicles 1 for which maintenance has been completed.

[0046] The storage unit 22 is configured to include storage means such as a volatile or non-volatile memory, a HDD, etc. The storage unit 22 stores various programs executed by the control unit 26 and various data.

[0047] The display unit 23 is located approximately in the center of the terminal and is a display screen that displays various information and provides it to the station worker. The display unit 23 can display various information about the target shared vehicle 1 based on the worker's operation.

[0048] The input unit 24 is, for example, a touch panel formed overlaid on the display unit 23, and inputs various information to the manager terminal 20. The notification unit 25 notifies the manager terminal 20 when it receives information about an abnormal air pressure in the target shared vehicle 1 from the cloud server 30. The notification unit 25 may, for example, display on the display unit 23 the location information of the shared vehicle 1 and tire 2 in which the abnormal air pressure has occurred, and may additionally be configured to turn on an indicator light or emit an alarm. The control unit 26 has a CPU, and performs predetermined processing based on information received from the cloud server 30 via the communication unit 21 or data stored in the memory unit 22.

[0049] Next, the operation of the cloud server 30 according to this embodiment will be described. Fig. 4 is a flowchart showing the operation procedure of the tire pressure management system. Fig. 5 is a flowchart showing the operation procedure of the tire pressure management device in Fig. 4 for determining a flat tire.

[0050] 4, when the shared vehicle 1 is returned to the station (step ST1), the control unit 26 of the manager terminal 20 determines whether a predetermined time has passed since the return (step ST2). This predetermined time corresponds to the period until the tires 2 of the shared vehicle 1 are cooled, and the control unit 26 determines whether, for example, 15 minutes have passed since the return. In this determination, if the predetermined time has not passed (step ST2; No), there may be a large fluctuation (decrease) in the temperature of the tire 2, which will result in a fluctuation (decrease) in the air pressure as well. Therefore, by waiting until the predetermined time has passed, a more accurate determination can be made.

[0051] On the other hand, if the predetermined time has elapsed (step ST2; Yes), the control unit 40 of the cloud server 30 executes a puncture determination process (step ST3). The control unit 40 of the cloud server 30 then determines whether or not a normal puncture has been determined for the tire 2 of the shared vehicle 1 (step ST4). If a normal puncture has been determined (step ST4; Yes), the control unit 40 of the cloud server 30 proceeds to step ST7. If a normal puncture has not been determined (step ST4; No), the control unit 40 of the cloud server 30 proceeds to step ST5. If a slow leak has been determined (step ST5; Yes), the control unit 40 of the cloud server 30 proceeds to step ST7. If a slow leak has not been determined (step ST5; No), the control unit 40 of the cloud server 30 proceeds to step ST6. In this determination, if a spontaneous leakage is determined (step ST6; Yes), the process proceeds to step ST7, and if a spontaneous leakage is not determined (step ST6; No), the process ends.

[0052] If the determination is a normal puncture, slow leak, or natural leak, the control unit 40 of the cloud server 30 notifies the administrator terminal 20 managing the station where the target shared vehicle 1 is parked of the type of air pressure abnormality via the communication unit 31 (step ST7). Specifically, if the control unit 40 determines that the type of air pressure abnormality of the target shared vehicle 1 is a puncture (normal puncture), it notifies the administrator terminal 20 of the station where the shared vehicle 1 is parked and the car sharing management server that a tire 2 of the shared vehicle 1 has been punctured. In this case, the car sharing management server checks whether there is a reservation for use of the shared vehicle 1 on that day, and if there is a reservation, it transfers the reservation to another shared vehicle 1 of the same class and notifies the user of this fact. Furthermore, when the administrator terminal 20 is notified of the puncture, the station repairs the puncture of the tire 2 of the shared vehicle 1.

[0053] Furthermore, if the control unit 40 determines that the type of air pressure abnormality in the target shared vehicle 1 is a slow leak, it notifies the administrator terminal 20 of the station for this shared vehicle 1 and the car sharing management server that a slow leak has occurred in the tire 2 of the shared vehicle 1. In this case, if a reservation for use of the shared vehicle 1 has been made for that day, the car sharing management server preferably notifies the user to request that the shared vehicle 1 be replenished with air. If the user performs the air replenishment, the car sharing management server then sends, for example, a discount coupon for the usage fee. Meanwhile, at the station side that has been notified of the slow leak via the administrator terminal 20, if there is no reservation for use of the shared vehicle 1, the station side checks for damage to the air valve or wheel of the tire 2 or repairs the puncture.

[0054] Furthermore, if the control unit 40 determines that the type of air pressure abnormality in the target shared vehicle 1 is a natural leak, it notifies the administrator terminal 20 of the station for this shared vehicle 1 and the car sharing management server that a natural leak has occurred in the tire 2 of the shared vehicle 1. In this case, if a reservation for use of the shared vehicle 1 has been made for that day, the car sharing management server preferably notifies the user to request that the shared vehicle 1 be replenished with air. If the user performs the air replenishment, the car sharing management server then sends, for example, a discount coupon for the usage fee. Meanwhile, the station that has been notified of the natural leak via the administrator terminal 20 performs maintenance on the tire 2 (replenishes air or checks for damage to the tire 2's air valve, wheel, etc.) if there is no reservation for use of the shared vehicle 1.

[0055] Next, we will explain the puncture determination process of the cloud server 30. As shown in Figure 5, the cloud server 30 uses the information acquisition unit 32 to acquire air pressure information (sensor information (Pi, Ti)) of each tire 2 of the shared vehicle 1 received from the sensor receiving terminal 10 at a predetermined timing (step ST11). This air pressure information includes the vehicle ID of the shared vehicle 1, the sensor ID of each sensor 3, the correspondence between the sensor ID and the wheel position, and the air pressure and temperature of each tire 2 detected by each sensor 3.

[0056] Next, the cloud server 30 sets, via the reference information setting unit 33, reference information (Po, To) including the reference air pressure and reference temperature of the tire 2 (step ST12). In this embodiment, the reference information setting unit 33 sets, as the reference temperature, the average value of the temperature-converted air pressure of the same tire 2 over a predetermined period of time in the past (e.g., the most recent 10 days).

[0057] Next, the cloud server 30 calculates the temperature-converted air pressure (Pi') converted into the air pressure at the reference temperature based on the air pressure information (sensor information (Pi, Ti)) and the set reference information (Po, To) using the temperature-converted air pressure calculation unit 34 (step ST13). The temperature-converted air pressure calculation unit 34 converts the air pressure (Pi) of the tire 2 into the air pressure at the reference temperature (To) based on, for example, the Boyle-Charles law.

[0058] Next, the cloud server 30 sets the natural leakage threshold K3 based on the natural leakage air pressure using the natural leakage threshold setting unit 38 (step ST14). In this case, the natural leakage air pressure may be estimated based on the operating rate of the shared vehicle 1 or may be estimated based on a predetermined relational expression.

[0059] Next, the cloud server 30 determines, via the first abnormality determination unit 36A, whether the difference between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is equal to or greater than a first threshold value K1 (step ST15). The first threshold value K1 is a threshold value for determining whether or not there is an air pressure abnormality, and is a threshold value at which at least natural leakage from the tire 2 is estimated. In this embodiment, assuming that the maximum air pressure of the tire 2 specified by JATMA is 240 kPa, the first threshold value K1 is set to approximately 3% (8 kPa) of the maximum air pressure. If, in this determination, the difference between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is equal to or greater than the first threshold value K1 (step ST15; Yes), the cloud server 30 proceeds to step ST16.

[0060] Furthermore, if the difference value between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is not greater than the first threshold value K1 (step ST15; No), the first abnormality judgment unit 36A judges that there is no air pressure abnormality in the tire 2 of the shared vehicle 1 (step ST21) and terminates the processing.

[0061] Next, the cloud server 30 determines, via the first abnormality determination unit 36A, whether the difference between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is equal to or greater than a second threshold value K2 (step ST16). The second threshold value K2 serves as a criterion for determining whether the type of air pressure abnormality is a puncture or a slow leak of the tire 2, and is the threshold value at which a puncture of the tire 2 is estimated. The second threshold value K2 is greater than the first threshold value K1. In this embodiment, assuming that the maximum air pressure of the tire 2 specified by JATMA is 240 kPa, the second threshold value K2 is set to approximately 20% (50 kPa) of the maximum air pressure. If, in this determination, the difference between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is not equal to or greater than the second threshold value K2 (step ST16; No), the cloud server 30 proceeds to step ST17.

[0062] On the other hand, if this determination shows that the difference between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is equal to or greater than the second threshold value K2 (step ST16; Yes), the cloud server 30 proceeds to step ST20. In this case, the first abnormality determination unit 36A determines that the type of abnormality in the tire 2 of the shared vehicle 1 is a puncture (step ST20), and ends the processing. In this way, in this embodiment, the first abnormality determination unit 36A can appropriately determine whether there is an air pressure abnormality and whether the type of abnormality is a puncture of the tire 2, using the two-stage threshold values ​​K1 and K2.

[0063] Next, the cloud server 30, using the second abnormality determination unit 36B, determines whether the difference between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is equal to or less than the natural leakage threshold K3 (step ST17). This natural leakage threshold K3 was set in step ST14 described above and serves as a criterion for determining whether the type of air pressure abnormality is a slow leak or a natural leak of the tire 2. In this embodiment, if the initial inflation pressure of the tire 2 is the maximum air pressure (240 kPa) specified by JATMA and the natural leakage air pressure that will naturally leak over a predetermined unit period (one month) is estimated to be 6% (14 kPa), this 6% (14 kPa) is set as the natural leakage threshold K3. This natural leakage threshold K3 is set to a value greater than the first threshold K and less than the second threshold K2.

[0064] In this determination, if the difference value between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is equal to or less than the natural leakage threshold value K3 (step ST17; Yes), the cloud server 30 proceeds to step ST18. In this case, the second abnormality determination unit 36B determines that the abnormality type of the tire 2 of the shared vehicle 1 is natural leakage (step ST18) and ends the process. On the other hand, if the difference value between the reference air pressure (Po) and the temperature-converted air pressure (Pi') is not equal to or less than the natural leakage threshold value K3 (step ST17; No), the cloud server 30 proceeds to step ST19. In this case, the second abnormality determination unit 36B determines that the abnormality type of the tire 2 of the shared vehicle 1 is slow leakage (step ST19) and ends the process. As described above, in the present embodiment, the second abnormality determination unit 36B can appropriately determine whether the type of air pressure abnormality is slow leakage or natural leakage of the tire 2 using the natural leakage threshold value K3. Therefore, based on the determination result, maintenance work (air replenishment or puncture repair) for the tire 2 can be appropriately determined, thereby reducing the amount of work required.

[0065] Second Embodiment Next, a second embodiment will be described. FIG. 6 is a flowchart illustrating the operational procedure of the puncture detection process according to the second embodiment. FIG. 7 is a graph illustrating the time course of the temperature-converted air pressure and temperature of a tire. In the first embodiment described above, the second abnormality determination unit 36B is configured to determine whether the type of air pressure abnormality is a slow leak or a natural leak of the tire 2 using a set natural leak threshold K3. In contrast, in the second embodiment, the second abnormality determination unit 36B is configured to determine the trends of change in the temperature-converted air pressure and temperature at two consecutive points in time based on paired data of the temperature-converted air pressure and the temperature, and to determine whether the type of air pressure abnormality is a slow leak or a natural leak of the tire 2 based on the difference in these trends. The configuration of the cloud server 30 (air pressure management device) is substantially the same as in the first embodiment, and the puncture detection process shown in FIG. 6 is the same as in the first embodiment, except that step ST117 differs from step ST17 in the first embodiment. Therefore, a description of the same configuration and operation will be omitted.

[0066] As shown in FIG. 6 , if the difference between the reference air pressure (Po) and the temperature-converted air pressure (Pi′) is not equal to or greater than the second threshold value K2 (step ST116; No), the cloud server 30 proceeds to step ST117. Next, the cloud server 30, using the second abnormality determination unit 36B, determines whether the change trends of the temperature-converted air pressure and the temperature at two consecutive points in time are the same (step ST117). Generally, the tire 2 is filled with air at a predetermined pressure (temperature-converted air pressure) in an enclosed space, and this air pressure changes in a similar manner to the temperature, for example, according to the Boyle-Charles law. Specifically, if the temperature inside the tire 2 increases, the temperature-converted air pressure also increases, and if the temperature inside the tire 2 decreases, the temperature-converted air pressure also decreases. On the other hand, if the change trends of the temperature-converted air pressure and the temperature differ, i.e., if the temperature inside the tire 2 increases while the temperature-converted air pressure decreases or remains constant, it is considered that an abnormality has occurred in the tire 2.

[0067] As shown in FIG. 7, the temperature difference ΔT between any two consecutive points in time is used as the temperature inside the tire 2. ａis positive (plus), and the temperature converted air pressure difference ΔP ａ In this case, the temperature-converted air pressure and temperature change trends are the same. Similarly, the temperature difference ΔT between any two consecutive points in time ｂ and temperature converted air pressure difference ΔP ｂ are both negative, and the temperature-converted air pressure and temperature change trends are the same.

[0068] On the other hand, the temperature difference ΔT between any two consecutive points in time ｃ is positive (plus), while the temperature converted air pressure difference ΔP ｃ is negative, and the sign of the change is different. In this case, the temperature converted air pressure and the temperature change trends are different (not the same), so an air pressure abnormality is determined.

[0069] In the present embodiment, if the second abnormality determination unit 36B determines in this determination that the trend of change in the temperature-converted air pressure and the trend of change in temperature are the same (step ST117; Yes), the cloud server 30 proceeds to step ST118. In this case, the second abnormality determination unit 36B determines that the abnormality type of the tire 2 of the shared vehicle 1 is a spontaneous leak (step ST118) and ends the process. On the other hand, if the trend of change in the temperature-converted air pressure and the trend of change in temperature are different (step ST117; No), the cloud server 30 proceeds to step ST119. In this case, the second abnormality determination unit 36B determines that the abnormality type of the tire 2 of the shared vehicle 1 is a slow leak (step ST119) and ends the process.

[0070] As described above, in this embodiment, the second abnormality determination unit 36B determines the change trends of the temperature-converted air pressure and the temperature at two consecutive points in time based on the paired data of the temperature-converted air pressure and the temperature, and can appropriately determine whether the type of air pressure abnormality is a slow leak or a natural leak from the tire 2 based on the difference in these trends. Therefore, the maintenance work (air replenishment or puncture repair) for the tire 2 can be appropriately determined based on this determination result, thereby reducing the amount of work required. Note that the second abnormality determination unit 36B only needs to determine the change trends of the temperature-converted air pressure and the temperature at at least two consecutive points in time. In addition to the above configuration, for example, the second abnormality determination unit 36B may be configured to calculate approximate equations for the temperature-converted air pressure and the temperature using multiple paired data of the temperature-converted air pressure and the temperature, and appropriately determine whether the type of air pressure abnormality is a slow leak or a natural leak from the tire 2 based on the difference in the signs (positive or negative) of the slopes of these approximate equations.

[0071] [Third Embodiment] Next, a third embodiment will be described. Fig. 8 is a block diagram showing the functional configuration of a cloud server according to the third embodiment. This third embodiment differs from the first and second embodiments in that the abnormality determination unit 136 of the cloud server 130 (air pressure management device) includes a third abnormality determination unit 36C. The other configurations are substantially the same as those of the above-described embodiments, and therefore will not be described again.

[0072] The storage unit 39 of the cloud server 130 stores a data group indicating the correspondence between the temperature-converted air pressure of the tire 2, temperature, information about the operation of the shared vehicle 1, and information about the tire, as well as a learning model generated using the data group. The data group includes a large number of sets of data each representing a tire 2 temperature and a temperature-converted air pressure converted by the temperature, as well as information about the vehicle operation corresponding to the set of data (e.g., GNSS information, engine on / off information, vehicle speed pulse information, etc.) and information about the tire (e.g., tire size, mounting position, reference natural leakage rate, internal surface area, internal volume, etc.). The learning model is generated by performing machine learning using the data group as feature quantities. Furthermore, instead of the temperature-converted air pressure of the tire 2, a physical quantity correlated with the air pressure (e.g., wheel rotation speed) may be used. Furthermore, instead of the tire temperature, the outside air temperature may be used. With this configuration, for example, even in a configuration where a TPMS sensor (sensor 3) is not provided in the tire 2, the tire pressure of the tire 2 can be indirectly estimated, so that, for example, users of vehicles equipped with an indirect TPMS, mobility service providers, taxi operators, etc. can easily manage tire pressure without adding a new TPMS sensor, while suppressing implementation costs. In this way, by customizing the tire pressure management device and tire pressure management method, tire pressure abnormalities can be appropriately determined while meeting the diverse needs of users.

[0073] The third abnormality determination unit 36C of the abnormality determination unit 136 determines the type of air pressure abnormality using the above-mentioned data group. Specifically, after generating a learning model in advance using a method such as a decision tree or random forest, the temperature-converted air pressure of the tire 2, temperature, information about the operation of the shared vehicle 1, and information about the tire acquired at a predetermined timing are sequentially input. This determines whether an air pressure abnormality exists and easily determines whether the type of air pressure abnormality is a natural leak, a slow leak, or a puncture. In addition, the learning model can be updated using additional data groups acquired after a certain period of time has passed. Periodic updates can improve the accuracy of determination.

[0074] In this embodiment, the determination of an abnormal air pressure by the third abnormality determination unit 36C is performed independently of the determination of an abnormal air pressure by the first abnormality determination unit 36A and the second abnormality determination unit 36B, and the respective determinations are combined to make a final determination. For example, the determinations by the first abnormality determination unit 36A and the second abnormality determination unit 36B may be used as a primary determination, and the determination of an abnormal air pressure by the third abnormality determination unit 36C may be used as a secondary determination, and if the two determinations differ, the result of the primary determination may take precedence. Alternatively, the determination of an abnormal air pressure by the third abnormality determination unit 36C may be used as a primary determination, and the determinations by the first abnormality determination unit 36A and the second abnormality determination unit 36B may be used as secondary determinations.

[0075] As described above, the cloud server 30 according to this embodiment includes an information acquisition unit 32 that acquires sensor information including the air pressure and temperature of the tire 2 mounted on the shared vehicle 1 at a predetermined timing; a reference information setting unit 33 that sets reference information including the reference air pressure and reference temperature of the tire 2; a temperature-converted air pressure calculation unit 34 that calculates the temperature-converted air pressure of the tire 2 at the reference temperature based on the sensor information and the reference information; and an abnormality determination unit 36 ​​that determines the presence or absence of an abnormality in the tire 2 and the type of the abnormality based on a comparison result between the reference air pressure and the temperature-converted air pressure. The abnormality determination unit 36 ​​includes a first abnormality determination unit 36A that determines that there is an abnormality in the tire 2 when the difference value between the reference air pressure and the temperature-converted air pressure is equal to or greater than a first threshold value K1, and that determines the type of abnormality to be a puncture of the tire 2 when the difference value is equal to or greater than a second threshold value K2 that is greater than the first threshold value; and a second abnormality determination unit 36B that determines whether the type of abnormality is a slow leak or a spontaneous leak of the tire 2 when the difference value is equal to or greater than the first threshold value K1 and less than the second threshold value K2. According to this configuration, the presence or absence of an abnormality in the air pressure of the tire 2 and the type of abnormality can be determined with high accuracy using the two-stage threshold values ​​K1 and K2.

[0076] Furthermore, the cloud server 30 according to this embodiment includes a natural leakage air pressure estimation unit 37 that estimates the natural leakage air pressure of the tire 2 over a predetermined unit period, and a natural leakage threshold setting unit 38 that sets a natural leakage threshold K3 that corresponds to the natural leakage air pressure, and the second abnormality determination unit 36B compares the difference value with the natural leakage threshold K3 when the difference value is equal to or greater than the first threshold K1 and smaller than the second threshold K2, and determines the type of abnormality as natural leakage when the difference value is equal to or smaller than the natural leakage threshold K3, and determines the type of abnormality as slow leakage when the difference value is greater than the natural leakage threshold K3. With this configuration, the use of the natural leakage threshold K3 makes it possible to appropriately determine whether the abnormality is natural leakage or slow leakage.

[0077] Furthermore, in the cloud server 30 according to this embodiment, the natural leakage air pressure estimation unit 37 estimates the natural leakage air pressure based on the operating rate of the shared vehicle 1, and therefore, can estimate this natural leakage air pressure with high accuracy.

[0078] Furthermore, in the cloud server 30 according to this embodiment, the natural leakage air pressure estimation unit 37 estimates the natural leakage air pressure using a relational equation showing the relationship between the ratio A / V of the inner surface area A and the inner volume V of the tire 2 and the natural leakage rate, and therefore the natural leakage air pressure can be estimated easily and accurately.

[0079] Furthermore, in the cloud server 30 according to this embodiment, the second abnormality determination unit 36B determines the change trends of the temperature-converted air pressure and the temperature at two consecutive points in time based on the paired data of the temperature-converted air pressure and the temperature, and determines the type of abnormality as a natural leak if the change trends of the temperature-converted air pressure and the temperature are the same, and determines the type of abnormality as a slow leak if the change trends of the temperature-converted air pressure and the temperature are different. This configuration makes it possible to appropriately determine whether the type of air pressure abnormality is a slow leak or a natural leak from the tire 2.

[0080] Furthermore, the cloud server 130 according to this embodiment is equipped with a memory unit 39 that stores a data group indicating the correspondence between the air pressure of the tire 2 or a physical quantity correlated with the air pressure, the temperature of the tire 2 or the outside air temperature, information related to the operation of the vehicle, and information related to the tire 2, and a third abnormality determination unit 36C that classifies the type of abnormality in the tire 2 into a puncture, a slow leak, and a natural leak by using the data group as learning data, so that it is possible to easily determine whether the type of air pressure abnormality is a natural leak, a slow leak, or a puncture.

[0081] The cloud server 30 according to this embodiment includes an average value calculation unit 35 that calculates an average value of the temperature-converted air pressure over a predetermined period, and the reference information setting unit 33 sets the average value of the temperature-converted air pressure as the reference air pressure. With this configuration, the reference air pressure is periodically updated with the average value of the temperature-converted air pressure, so that an appropriate reference air pressure can be used, and the presence or absence of an air pressure abnormality in the tire 2 can be accurately determined.

[0082] In the cloud server 30 according to this embodiment, the information acquisition unit 32, the temperature converted air pressure calculation unit 34, and the abnormality determination unit 36 ​​execute their operations after the shared vehicle 1 is parked in a specified parking space and a predetermined time has passed since the shared vehicle 1 has stopped operating. With this configuration, the tire 2 has cooled to a certain extent, allowing the abnormality determination unit 36 ​​to accurately perform the puncture determination process.

[0083] In the cloud server 30 according to this embodiment, the vehicle is a shared vehicle that is shared by unspecified users, and therefore, for example, it is possible to appropriately determine whether or not there is an abnormality in the air pressure of the tire 2 of the shared vehicle 1 used for car sharing, and the type of abnormality.

[0084] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. In the above-described embodiments, the cloud server 30 manages the air pressure of the tires 2 mounted on the shared vehicles 1 used in a car sharing business. However, for example, the cloud server 30 may manage the air pressure of the tires 2 mounted on the vehicles of pre-registered users.

[0085] REFERENCE SIGNS LIST 1 Shared vehicle (vehicle) 2 Tire 3 Sensor 3a Air pressure sensor 3b Temperature sensor 10 Sensor receiving terminal 20 Administrator terminal 30, 130 Cloud server (air pressure management device) 31 Communication unit 32 Information acquisition unit 33 Reference information setting unit 34 Temperature converted air pressure calculation unit 35 Average value calculation unit 36, 136 Abnormality determination unit 36A First abnormality determination unit 36B Second abnormality determination unit 36C Third abnormality determination unit 37 Natural leakage air pressure estimation unit 38 Natural leakage threshold setting unit 39 Memory unit 40 Control unit 50 Communication network 100 Tire pressure management system A Tire inner surface area V Tire inner volume

Claims

1. An air pressure management device comprising: an information acquisition unit that acquires sensor information including the air pressure and temperature of a tire mounted on a vehicle at a predetermined timing; a reference information setting unit that sets reference information including a reference air pressure and a reference temperature of the tire; a temperature converted air pressure calculation unit that calculates the temperature converted air pressure of the tire at the reference temperature based on the sensor information and the reference information; and an abnormality determination unit that determines the presence or absence of an abnormality in the tire and the type of the abnormality based on a comparison result between the reference air pressure and the temperature converted air pressure, wherein the abnormality determination unit comprises a first abnormality determination unit that determines that there is an abnormality in the tire when a difference value between the reference air pressure and the temperature converted air pressure is equal to or greater than a first threshold, and that determines the type of the abnormality to be a puncture of the tire when the difference value is equal to or greater than the first threshold and less than the second threshold, and a second abnormality determination unit that determines whether the type of the abnormality is a slow leak or a natural leak of the tire when the difference value is equal to or greater than the first threshold and less than the second threshold.

2. An air pressure management device as described in claim 1, comprising a natural leakage air pressure estimation unit that estimates the natural leakage air pressure of the tire in a specified unit period, and a natural leakage threshold setting unit that sets a natural leakage threshold corresponding to the natural leakage air pressure, wherein the second abnormality determination unit compares the difference value with the natural leakage threshold when the difference value is greater than or equal to the first threshold and less than the second threshold, and determines the type of the abnormality to be the natural leakage when the difference value is less than or equal to the natural leakage threshold, and determines the type of the abnormality to be the slow leak when the difference value is greater than the natural leakage threshold.

3. An air pressure management device as described in claim 2, wherein the natural leakage air pressure estimation unit estimates the natural leakage air pressure based on an operating rate of the vehicle.

4. An air pressure management device as described in claim 2, wherein the natural leakage air pressure estimation unit estimates the natural leakage air pressure using a relational equation that shows the relationship between the ratio of the inner surface area and inner volume of the tire and the natural leakage air pressure.

5. The air pressure management device described in claim 1, wherein the second abnormality determination unit determines the trend of change in the temperature-converted air pressure and the temperature at least for two consecutive points in time based on a pair of data of the temperature-converted air pressure and the temperature, and determines the type of the abnormality to be the natural leak if the trend of change in the temperature-converted air pressure and the trend of change in the temperature are identical, and determines the type of the abnormality to be the slow leak if the trend of change in the temperature-converted air pressure and the trend of change in the temperature are different.

6. An air pressure management device as described in claim 1, comprising: a memory unit that stores a group of data indicating the correspondence between the tire air pressure or a physical quantity correlated with the air pressure, the tire temperature or the outside air temperature, information regarding the operation of the vehicle, and information regarding the tire; and a third abnormality determination unit that uses the group of data as learning data to classify the type of abnormality of the tire into the puncture, the slow leak, and the natural leak.

7. An air pressure management device as described in claim 1, further comprising an average value calculation unit that calculates an average value of the temperature converted air pressure over a predetermined period of time, and the reference information setting unit sets the average value of the temperature converted air pressure as the reference information.

8. An air pressure management device as described in claim 1, wherein the information acquisition unit, the temperature converted air pressure calculation unit and the abnormality determination unit perform their operations after the vehicle is parked in a specified parking space and a predetermined time has elapsed since the operation of the vehicle has ceased.

9. The air pressure management device according to claim 8, wherein the vehicle is a shared vehicle that is shared by unspecified users.

10. An air pressure management device comprising: an information acquisition unit which acquires sensor information including the air pressure and temperature of a tire mounted on a vehicle at a predetermined timing; a reference information setting unit which sets reference information including a reference air pressure and reference temperature of the tire; a temperature converted air pressure calculation unit which calculates the temperature converted air pressure of the tire at the reference temperature based on the sensor information and the reference information; and an abnormality determination unit which determines the presence or absence of an abnormality in the tire and the type of the abnormality based on a comparison result between the reference air pressure and the temperature converted air pressure, wherein the abnormality determination unit determines the trend of change in the temperature converted air pressure and the temperature at least for two temporally consecutive points based on paired data of the temperature converted air pressure and the temperature, and determines the type of the abnormality to be a natural leak if the trend of change in the temperature converted air pressure and the trend of change in the temperature are identical, and determines the type of the abnormality to be a slow leak if the trend of change in the temperature converted air pressure and the trend of change in the temperature are different.

11. An air pressure management method comprising the steps of: acquiring sensor information including the air pressure and temperature of a tire mounted on a vehicle at a predetermined timing; setting reference information including a reference air pressure and reference temperature of the tire; calculating a temperature converted air pressure of the tire at the reference temperature based on the sensor information and the reference information; and determining the presence or absence of an abnormality in the tire and the type of the abnormality based on a comparison result between the reference air pressure and the temperature converted air pressure, wherein in the step of determining the presence or absence of an abnormality in the tire and the type of the abnormality, if a difference value between the reference air pressure and the temperature converted air pressure is equal to or greater than a first threshold value, it is determined that there is an abnormality in the tire, and if the difference value is equal to or greater than a second threshold value that is greater than the first threshold value, it is determined that the type of the abnormality is a puncture of the tire, and if the difference value is equal to or greater than the first threshold value and less than the second threshold value, it is determined that the type of the abnormality is a slow leak or a natural leak of the tire.

12. An air pressure management method comprising the steps of: acquiring sensor information including the air pressure and temperature of a tire mounted on a vehicle at a predetermined timing; setting reference information including a reference air pressure and reference temperature of the tire; calculating a temperature converted air pressure of the tire at the reference temperature based on the sensor information and the reference information; and determining the presence or absence of an abnormality in the tire and the type of the abnormality based on a comparison result between the reference air pressure and the temperature converted air pressure, wherein in the step of determining the presence or absence of an abnormality in the tire and the type of the abnormality, the temperature converted air pressure and the temperature are respectively determined based on paired data of the temperature converted air pressure and the temperature, and if the trend of change in the temperature converted air pressure and the trend of change in the temperature are identical, the type of the abnormality is determined to be a natural leak, and if the trend of change in the temperature converted air pressure and the trend of change in the temperature are different, the type of the abnormality is determined to be a slow leak.

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