阅读说明：本技术 轮胎气压监视系统、轮胎气压监视方法、轮胎气压监视程序以及车辆 (Tire pressure monitoring system, tire pressure monitoring method, tire pressure monitoring program, and vehicle ) 是由 堀越正太郎 于 2018-05-25 设计创作，主要内容包括：轮胎气压监视系统(30)具备：数据获取部(101)，其从安装于轮胎的传感器(50FL)、传感器(50FR)、传感器(50RL)以及传感器(50RR)获取表示轮胎的轮胎气压和轮胎的轮胎温度的数据；刺破判定部(103)，其基于由轮胎气压与轮胎温度的关系所规定的刺破判定阈值，来判定轮胎是否被刺破；警报处理部(105)，在通过刺破判定部(103)判定为轮胎被刺破的情况下，其产生与由于轮胎气压下降而产生的警报不同的表示轮胎被刺破的警报。(A tire air pressure monitoring system (30) is provided with: a data acquisition unit (101) that acquires data indicating the tire air pressure of the tire and the tire temperature of the tire from a sensor (50FL), a sensor (50FR), a sensor (50RL) and a sensor (50RR) that are mounted to the tire; a puncture determination unit (103) that determines whether or not a tire has punctured, based on a puncture determination threshold value defined by the relationship between the tire air pressure and the tire temperature; and an alarm processing unit (105) which, when the puncture determination unit (103) determines that the tire has been punctured, generates an alarm indicating that the tire has been punctured, said alarm being different from an alarm generated by a drop in tire air pressure.)

1. A tire air pressure monitoring system that monitors air pressure of a tire mounted on a vehicle, the tire air pressure monitoring system comprising:

a data acquisition unit that acquires data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor attached to the tire;

a puncture determination unit that determines whether or not the tire is punctured based on a puncture determination threshold value defined by a relationship between the tire air pressure and the tire temperature; and

and an alarm processing unit that generates an alarm indicating that the tire is punctured, the alarm being different from an alarm generated by a decrease in the tire air pressure, when the puncture determination unit determines that the tire is punctured.

2. A tire air pressure monitoring system that monitors air pressure of a tire mounted on a vehicle, the tire air pressure monitoring system comprising:

a data acquisition unit that acquires data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor attached to the tire; and

a puncture determination unit that determines whether or not the tire is punctured based on a puncture determination threshold value based on a reference volume value calculated using a reference tire air pressure and a reference tire temperature,

wherein the puncture determination portion determines that the tire is punctured when the tire air pressure is lower than the puncture determination threshold value associated with the tire temperature.

3. The tire air pressure monitoring system according to claim 2,

the tire air pressure monitoring system includes an alarm processing unit that generates an alarm indicating that the tire is punctured, the alarm processing unit being different from a decrease in the tire air pressure, when the puncture determination unit determines that the tire is punctured.

4. The tire air pressure monitoring system according to claim 2 or 3,

the puncture determination threshold value is set to be 0.8 or more and 0.95 or less of the reference tire air pressure associated with the reference tire temperature, and the puncture determination threshold value is higher than an air pressure drop threshold value for determining a drop in the tire air pressure.

5. The tire air pressure monitoring system according to any one of claims 2 to 4,

the reference tire temperature is determined using a correction coefficient corresponding to at least one of the measurement accuracy of the sensor and the type of the tire.

6. The tire air pressure monitoring system according to any one of claims 2 to 5,

the reference tire air pressure is determined using a correction coefficient corresponding to at least one of the measurement accuracy of the sensor and the type of the tire.

7. The tire air pressure monitoring system according to any one of claims 2 to 6,

setting the reference tire air pressure as Ps, the reference tire temperature as Ts, the tire air pressure as P, the tire temperature as T, and the correction coefficient of the tire temperature as k_TSetting a correction coefficient of the tire air pressure to k_PIn the case of (1), by [ numerical expression 1]]

[ numerical formula 1]

To calculate said reference volume value Vs.

8. The tire air pressure monitoring system according to any one of claims 2 to 7,

the tire air pressure monitoring system includes:

a volume value setting unit for setting the reference volume value; and

a threshold value setting unit for setting the puncture determination threshold value,

wherein the volume value setting section sets the reference volume value based on a tire air pressure and a tire temperature of the tire without a puncture,

the threshold value setting portion is configured to set the puncture determination threshold value associated with the reference volume value set by the volume value setting portion.

9. The tire air pressure monitoring system according to any one of claims 1 to 8,

the puncture determination unit determines whether or not the tire is deflated based on a change in tire air pressure of the tire after inflation.

10. The tire air pressure monitoring system according to any one of claims 1 to 9,

the puncture determination unit determines whether or not the tire air pressure is lower than the puncture determination threshold value associated with the tire temperature, using at least one of the tire air pressure and the tire temperature after the measurement error of the sensor is corrected.

11. A tire air pressure monitoring method of monitoring air pressure of a tire mounted on a vehicle, the tire air pressure monitoring method comprising the steps of:

a step of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor attached to the tire;

determining whether the tire is punctured or not based on a puncture determination threshold value defined by a relationship between the tire air pressure and the tire temperature; and

and generating an alarm indicating that the tire is punctured, which is different from an alarm generated due to a decrease in the tire air pressure, when it is determined that the tire is punctured.

12. A tire air pressure monitoring method of monitoring air pressure of a tire mounted on a vehicle, the tire air pressure monitoring method comprising the steps of:

a step of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor attached to the tire; and

a step of determining whether or not the tire is punctured based on a puncture determination threshold value based on a reference volume value calculated using a reference tire air pressure and a reference tire temperature,

wherein in the step of making a determination, it is determined that the tire is punctured when the tire air pressure is lower than the puncture determination threshold value associated with the tire temperature.

13. A tire air pressure monitoring program that monitors air pressure of a tire mounted on a vehicle, the tire air pressure monitoring program causing a computer to execute:

a process of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor mounted to the tire;

a process of determining whether the tire is punctured or not based on a puncture determination threshold value specified by a relationship between the tire air pressure and the tire temperature; and

and a process of generating an alarm indicating that the tire is punctured, the alarm being different from an alarm generated due to a decrease in the tire air pressure, when it is determined that the tire is punctured.

14. A tire air pressure monitoring program that monitors air pressure of a tire mounted on a vehicle, the tire air pressure monitoring program causing a computer to execute:

a process of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor mounted to the tire; and

a process of determining whether the tire is punctured or not based on a puncture determination threshold value with reference to a reference volume value calculated using a reference tire air pressure and a reference tire temperature,

wherein in the processing of making a determination, it is determined that the tire is punctured when the tire air pressure is lower than the puncture determination threshold value associated with the tire temperature.

15. A vehicle mounted with the tire air pressure monitoring system according to any one of claims 1 to 10.

Technical Field

The present invention relates to a tire air pressure monitoring system, a tire air pressure monitoring method, a tire air pressure monitoring program, and a vehicle that monitor air pressure of tires mounted on the vehicle.

Background

In recent years, a Tire Pressure Monitoring System (TPMS) that monitors the air pressure (internal pressure) of tires mounted on a vehicle has been widely used. When the constantly monitored air pressure is lower than the threshold value, the tire air pressure monitoring system warns of the air pressure drop. Further, a tire air pressure monitoring system has been proposed which warns that a tire is punctured, which is different from a drop in air pressure (for example, patent document 1).

Specifically, the tire air pressure monitoring system disclosed in patent document 1 determines whether or not a tire has punctured based on the air pressure difference between the tires mounted on the vehicle and the amount of decrease from the reference air pressure.

Disclosure of Invention

The main purpose of the tire air pressure monitoring system to warn of a puncture is to notify a driver or the like of a state in which a protrusion such as a nail penetrates a tire and the air pressure gradually decreases due to air leakage (so-called slow air leakage) at an early stage, in contrast to a natural decrease in air pressure (natural leakage of air) due to a change in external temperature or the like.

However, in such a case, since the air pressure is gradually decreased, there is a limit to early warning of the puncture when the puncture is determined based on the air pressure difference and the amount of decrease from the reference air pressure.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a tire air pressure monitoring system, a tire air pressure monitoring method, a tire air pressure monitoring program, and a vehicle, which can detect a puncture due to air leakage filled in a tire at an early stage and accurately, in distinction from a natural drop in air pressure due to a change in outside air temperature or the like.

One embodiment of the present invention is a tire air pressure monitoring system (tire air pressure monitoring system 30),which monitors the air pressure of tires (tire 20FL, tire 20FR, tire 20RL, and tire 20RR) mounted on a vehicle (for example, vehicle 10), the tire air pressure monitoring system (tire air pressure monitoring system 30) includes: a data acquisition unit (data acquisition unit 101) that acquires data indicating a tire air pressure (tire air pressure P) of the tire and a tire temperature (tire temperature T) of the tire from sensors (sensor 50FL, sensor 50FR, sensor 50RL, and sensor 50RR) attached to the tire; a puncture determination unit (puncture determination unit 103) that determines a puncture determination threshold (puncture determination threshold P) based on a relationship between the tire air pressure and the tire temperature_TH) Determining whether the tire is punctured; and an alarm processing unit (alarm processing unit 105) that, when the puncture determination unit determines that the tire is punctured, generates an alarm indicating that the tire is punctured, the alarm processing unit (alarm processing unit 105) being different from an alarm generated by a decrease in the tire air pressure.

One aspect of the present invention is a tire air pressure monitoring system (tire air pressure monitoring system 30) that monitors air pressures of tires (tire 20FL, tire 20FR, tire 20RL, and tire 20RR) mounted on a vehicle (for example, vehicle 10), the tire air pressure monitoring system (tire air pressure monitoring system 30) including: a data acquisition unit (data acquisition unit 101) that acquires data indicating a tire air pressure (tire air pressure P) of the tire and a tire temperature (tire temperature T) of the tire from sensors (sensor 50FL, sensor 50FR, sensor 50RL, and sensor 50RR) attached to the tire; and a puncture determination unit (puncture determination unit 103) that determines a puncture determination threshold value (puncture determination threshold value P) based on a reference volume value (reference volume value Vs) calculated using the reference tire air pressure (reference tire air pressure Ps) and the reference tire temperature (reference tire temperature Ts)_TH) And a puncture determination unit that determines whether the tire is punctured, wherein the puncture determination unit determines that the tire is punctured when the tire air pressure is lower than the puncture determination threshold value associated with the tire temperature.

One aspect of the present invention is a tire air pressure monitoring method for monitoring air pressure of a tire mounted on a vehicle, the tire air pressure monitoring method including the steps of: a step of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor attached to the tire; determining whether the tire is punctured or not based on a puncture determination threshold value defined by a relationship between the tire air pressure and the tire temperature; and generating an alarm indicating that the tire is punctured, which is different from an alarm generated due to a decrease in the tire air pressure, when it is determined that the tire is punctured.

One aspect of the present invention is a tire air pressure monitoring method for monitoring air pressure of a tire mounted on a vehicle, the tire air pressure monitoring method including the steps of: a step of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor attached to the tire; and a step of determining whether or not the tire is punctured, based on a puncture determination threshold value based on a reference volume value calculated using a reference tire air pressure and a reference tire temperature, wherein in the step of determining, it is determined that the tire is punctured when the tire air pressure is lower than the puncture determination threshold value associated with the tire temperature.

One aspect of the present invention is a tire air pressure monitoring program for monitoring air pressure of a tire mounted on a vehicle, the tire air pressure monitoring program causing a computer to execute: a process of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor mounted to the tire; a process of determining whether the tire is punctured or not based on a puncture determination threshold value specified by a relationship between the tire air pressure and the tire temperature; and a process of generating an alarm indicating that the tire is punctured, which is different from an alarm generated due to a decrease in the tire air pressure, when it is determined that the tire is punctured.

One aspect of the present invention is a tire air pressure monitoring program for monitoring air pressure of a tire mounted on a vehicle, the tire air pressure monitoring program causing a computer to execute: a process of acquiring data indicating a tire air pressure of the tire and a tire temperature of the tire from a sensor mounted to the tire; and a process of determining whether or not the tire is punctured based on a puncture determination threshold value based on a reference volume value calculated using a reference tire air pressure and a reference tire temperature, in the process of determining, when the tire air pressure is lower than the puncture determination threshold value associated with the tire temperature, it is determined that the tire is punctured.

An aspect of the present invention is a vehicle equipped with the tire air pressure monitoring system.

Drawings

Fig. 1 is a schematic plan view of a vehicle 10 including a tire air pressure monitoring system 30.

Fig. 2 is a functional block diagram of the tire pressure monitoring system 30.

Fig. 3 is a diagram showing a flow of an initial setting operation of the tire air pressure monitoring system 30.

Fig. 4 is a diagram showing a flow of detection operation for detecting a puncture and a decrease in tire air pressure by the tire air pressure monitoring system 30.

Fig. 5A is a view showing an example of the relationship between the set tire temperature Tr and the estimated tire air pressure Pr (Pt ℃) (when the reference tire temperature Ts is set to 15 ℃ and the reference tire air pressure Ps is set to 230 kPa).

Fig. 5B is a diagram showing an example of the relationship between the set tire temperature Tr and the reference volume value Vs (when the reference tire air pressure Ps is 230 kPa).

Fig. 6 is a graph showing the relationship between the tire temperature T measured by the sensor and the tire air pressure P, the set tire temperature Tr, and the estimated tire air pressure Pr.

Fig. 7A is a diagram showing (one of) a state display example of the tire displayed by the TPMS main unit 100.

Fig. 7B is a diagram showing a state display example (second thereof) of the tire displayed by the TPMS main unit 100.

Fig. 7C is a diagram showing a state display example (third thereof) of the tire displayed by the TPMS main unit 100.

Fig. 7D is a diagram showing a state display example (fourth thereof) of the tire displayed by the TPMS main unit 100.

Fig. 8A is a graph showing an example of a measurement error (pressure difference) of the sensor.

Fig. 8B is a diagram showing an example of a measurement error (temperature difference) of the sensor.

Fig. 9 is a schematic plan view and a schematic network configuration diagram of a vehicle 10A according to another embodiment.

Fig. 10 is a schematic plan view of a vehicle 10B according to another embodiment.

Detailed Description

Hereinafter, embodiments will be described based on the drawings. The same or similar reference numerals are attached to the same functions and structures, and the description thereof is appropriately omitted.

(1) General structure of vehicle including tire pressure monitoring system

Fig. 1 is a schematic plan view of a vehicle 10 including a tire air pressure monitoring system 30. As shown in fig. 1, the vehicle 10 is a four-wheel automobile. The type of the vehicle 10 is not particularly limited, and may be a car, a truck, a bus, or a construction vehicle. As described later, the rear wheel may be a dual tire.

Tires 20FL, 20FR, 20RL, and 20RR are mounted at the respective wheel positions of vehicle 10. The tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR are tires assembled to a rim (may also be referred to as a tire-rim assembly).

The tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR are mounted at positions of the front left wheel, the front right wheel, the rear left wheel, and the rear right wheel, respectively.

The tire air pressure monitoring system 30 monitors the air pressure of tires mounted on the vehicle 10. The tire air pressure monitoring system 30 is referred to as a TMPS or the like. The tire air pressure monitoring system 30 is constituted by sensors mounted on the respective tires and the TPMS main unit 100.

The TPMS main unit 100 may be incorporated as a part of an Electronic Control Unit (ECU) mounted on the vehicle 10.

A sensor 50FL for measuring the air pressure (internal pressure) and temperature of the tire 20FL is mounted on the tire 20 FL. Similarly, the sensor 50FR, the sensor 50RL, and the sensor 50RR are mounted on the tire 20FR, the tire 20RL, and the tire 20 RR. Specifically, the sensor is attached to a rim on which a tire is mounted, a valve, an inner surface of the tire, or the like.

The TPMS main unit 100 is provided in the vehicle 10 for receiving wireless signals (electric waves) transmitted from the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50 RR.

(2) Functional block structure of tire pressure monitoring system

Next, the functional block configuration of the tire air pressure monitoring system 30 will be described. Fig. 2 is a functional block diagram of the tire pressure monitoring system 30. As shown in fig. 2, the tire air pressure monitoring system 30 is constituted by sensors (sensor 50FL, sensor 50FR, sensor 50RL, and sensor 50RR) mounted at respective wheel positions, and a TPMS main unit 100.

(2.1) sensor 50FL (sensor 50FR, sensor 50RL and sensor 50RR)

The sensor 50FL (the same applies to the sensor 50FR, the sensor 50RL, and the sensor 50RR) includes a temperature sensor 51, a pressure sensor 53, a sensor ID setting unit 55, and a transmitter 57. Next, the sensor 50FL will be described as an example.

The temperature sensor 51 is used to measure the temperature (tire temperature) in the air chamber of the tire 20FL assembled to the rim. As the temperature sensor 51, for example, a semiconductor type temperature sensor can be used.

The pressure sensor 53 is used to measure the pressure in the air chamber of the tire 20FL (internal pressure: hereinafter referred to as tire air pressure). For example, a capacitance type pressure sensor can be used as the pressure sensor 53.

The measurement accuracy of the temperature sensor 51 and the pressure sensor 53 varies depending on the temperature in the air chamber of the tire 20 FL. In addition, the sensor 50FL may also include a sensor that measures acceleration.

The sensor ID setting unit 55 sets a sensor ID for identifying the sensor 50 FL. Specifically, the sensor ID setting unit 55 stores the identification information of the sensor 50FL, and supplies the stored identification information to the transmitter 57. The identification information may be about 2 bits of information, and when more information (such as a tire type) is included, more bits may be used. The identification information is multiplexed with the radio signal transmitted from the transmitter 57.

The transmitter 57 transmits a wireless signal (radio wave) obtained by multiplexing data representing the measured temperature output from the temperature sensor 51 and data representing the measured pressure (tire air pressure) output from the pressure sensor 53 to the TPMS main unit 100.

(2.2) TPMS Main Unit 100

The TPMS main unit 100 includes a receiver 90, a data acquisition unit 101, a puncture determination unit 103, an alarm processing unit 105, a volume value setting unit 107, a threshold value setting unit 109, and a display unit 111.

The receiver 90 is used to receive the wireless signal transmitted from the transmitter 57. The intensity (transmission power) and the frequency band of use of the radio signal may vary depending on the region of use of the tire air pressure monitoring system 30 and the type of the vehicle 10. In addition, the receiver 90 may be provided separately from the TPMS main unit 100 as a separate component.

The data acquisition portion 101 acquires data indicating the tire air pressure and the tire temperature from the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50 RR. Specifically, the data acquisition unit 101 acquires data indicating the tire air pressure and the tire temperature output from the receiver 90 for each sensor.

The puncture determination unit 103 is used to determine whether or not the tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR are punctured. Specifically, the puncture determination unit 103 determines the puncture determination threshold P based on the puncture determination_THAnd it is determined whether or not the tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR are punctured.

Here, a fluctuation factor of the tire air pressure will be described. The fluctuation factors of the pressure in the tires (tire 20FL, tire 20FR, tire 20RL, and tire 20RR) are (i) a change in the atmospheric temperature, (ii) a temperature change due to heat generation of the running tire and the like, (iii) natural leakage of air, and (iv) leakage due to (external factors) a puncture, an air valve failure, a rim crack or the like caused by a nail penetration or the like.

That is, a drop in tire air pressure (tire internal pressure) (blow-by) is caused by one of natural leakage and external factors. In the present embodiment, attention is paid to a change in the internal volume of the tire in order to determine a puncture (particularly, a slow puncture).

According to boyle-charles law, the tire internal volume can be expressed as follows.

Tire internal volume (V) × coefficient (k) × tire temperature (T)/tire internal pressure (P)

Here, when the tire internal volume of a predetermined reference is set as the reference volume value Vs, the tire internal volume V is largely changed by the occurrence of a puncture in the tire. In the present embodiment, the occurrence of a puncture is determined early by using such a change in the tire internal volume V.

The puncture determination unit 103 determines a puncture determination threshold value P based on the relationship between the tire air pressure P and the tire temperature T measured by the sensors 50FL, 50FR, 50RL and 50RR_THTo determine whether the tire is punctured.

Specifically, the puncture determination unit 103 determines the puncture determination threshold P based on the reference volume value Vs calculated using the reference tire air pressure Ps and the reference tire temperature Ts_THTo determine whether the tire is punctured.

The reference tire air pressure Ps is a predetermined reference tire air pressure, and generally corresponds to a standard set air pressure of the vehicle 10. The reference tire temperature Ts is a predetermined reference tire temperature, and generally corresponds to an atmospheric temperature at the time of tire air pressure adjustment (before running).

Further, the correction coefficient k corresponding to at least one of the measurement accuracy of the sensor and the type (including the size) of the tire may be used_PThe reference tire air pressure Ps and the tire air pressure P are corrected. That is, the correction coefficient k is used_PThe reference tire air pressure Ps and the tire air pressure P are determined.

Likewise, the measurement accuracy of the sensor and the type of tire may also be used (Including size) of the correction coefficient k_TThe reference tire temperature Ts and the tire temperature T are corrected. That is, the correction coefficient k is used_TThe reference tire temperature Ts and the tire temperature T are determined.

Thus, the range of fluctuation of the reference volume value Vs is defined, and a drop in tire air pressure P due to the influence of a temperature change and a puncture due to puncture can be determined with higher accuracy.

The reference tire air pressure is set to Ps, the reference tire temperature is set to Ts, the tire air pressure is set to P, the tire temperature is set to T, and the correction coefficient of the tire temperature T is set to k_TK is a correction coefficient of the tire air pressure P_PBy the Boyle's-Charles law

[ numerical formula 1]

To calculate the reference volume value Vs.

The tire air pressure P and the tire temperature T are actual tire air pressures and tire temperatures measured by the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50 RR.

In addition, the estimated tire air pressure Pr, which is the tire air pressure at the set tire temperature Tr, estimated using the reference volume value Vs can be expressed in the following manner.

[ numerical formula 2]

The set tire temperature Tr is a tire temperature (for example, -10 ℃ to 40 ℃) desirable for the tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR in a normal use environment, and corresponds to the estimated tire air pressure Pr.

Specifically, the estimated tire air pressure Pr at the tire temperature is calculated for the input temperature change condition (equation 2), that is, the input set tire temperature Tr. For example, when the reference tire temperature Ts is set to 15 ℃In the case, if the set tire temperature Tr is 5 ℃, the estimated tire air pressure Pr (P) is calculated as follows_5℃)。

[ numerical formula 3]

Here, the reference volume value Vs (1.252826) is a value calculated by (equation 1) when the reference tire temperature Ts is 15 ℃ and the reference tire air pressure Ps is 230kPa (however, the correction coefficient k is not applied)_TAnd a correction coefficient k_P). In the present embodiment, the estimated tire air pressure Pr (P) is based on the plurality of set tire temperatures Tr as shown in fig. 5A_t℃) To determine an equation for determining a puncture.

FIG. 5A shows a set tire temperature Tr and an estimated tire pressure Pr (P)_t℃) An example of the relationship (when the reference tire temperature Ts is set to 15 ℃ and the reference tire air pressure Ps is set to 230 kPa).

It is needless to say that a predetermined coefficient (α, β, and the like described later) may be applied to Tr and Pr., and when correcting a measurement error of a sensor as described later, the equation may not necessarily be a linear equation, but may be an n-th order equation.

That is, the puncture determination unit 103 may use the tire air pressure (tire air pressure P or estimated tire air pressure Pr (specifically Pr) corrected by the measurement error of the sensor^x) And tire temperature (tire temperature T or set tire temperature Tr) corrected for errors in measurement by the sensor, to determine whether or not the tire has punctured. Specifically, the puncture determination unit 103 may determine whether or not the tire air pressure corrected for the measurement error is lower than the puncture determination threshold P associated with the tire temperature_TH。

As described above, the measured tire air pressure P and the tire temperature T change with the time of travel, change in the atmospheric temperature, or the like. Therefore, the sensor is usedThe tire air pressures P measured by the sensors 50FL, 50FR, 50RL and 50RR are lower than the puncture determination threshold value P associated with the tire temperature T at the time of the measurement_THIn the case of (3), the puncture determination unit 103 determines that the tire is punctured.

Specifically, the puncture determination unit 103 determines whether or not the tire is punctured based on (expression 3).

[ numerical formula 4]

P≤P_TH

P_TH＝α×Pr^x+(β+k_p) … (formula 3)

Herein, Pr is^xIs the estimated tire air pressure Pr corresponding to the set tire temperature Tr, which means that the relationship of Tr and Pr is sometimes not a one-order equation but may be an n-order equation α is a temperature coefficient of the equation, β is a pressure coefficient of the equation α and β mean coefficients for correcting the set reference tire air pressure Ps, the reference tire temperature Ts, and a measurement error (instrumental error) of each sensor.

The puncture determination unit 103 can determine whether or not the tire air leakage has occurred based on changes in the tire air pressure P of the inflated tire 20FL, the inflated tire 20FR, the inflated tire 20RL, and the inflated tire 20 RR.

This is because, for example, when a puncture of a tire is repaired using a tire emergency puncture repair kit in which a tire is filled with a puncture repair liquid or when the puncture cannot be repaired, the tire internal volume V continues to gradually decrease, and the measured tire air pressure P changes and appears. In this case, although the amount of decrease in the tire air pressure P is small as described later, the puncture determination unit 103 can determine the presence or absence of puncture based on a change in the tire internal volume V.

When the puncture determination unit 103 determines that any one or more of the tires 20FL, 20FR, 20RL, and 20RR are punctured, the alarm processing unit 105 generates an alarm indicating that the tire is punctured, which is different from the alarm indicating that the tire air pressure P is decreased.

In particular, when the puncture determination unit 103 determines that any one or more of the tires 20FL, 20FR, 20RL, and 20RR are punctured, the alarm processing unit 105 generates an alarm indicating that the tire is punctured, which is different from an alarm generated by a drop in the tire air pressure P (an alarm based on the air pressure drop threshold). Specifically, the alarm processing unit 105 can generate an alarm indicating that the tire is punctured earlier than an alarm based on the air pressure drop threshold.

When the tire temperature T reaches the tire temperature alarm threshold, the alarm processing unit 105 generates an alarm indicating a temperature increase.

Specifically, the alarm processing unit 105 can generate an alarm (or no alarm) as shown in fig. 7A to 7D.

Fig. 7A to 7D show a state display example of the tire displayed by the TPMS main unit 100. As shown in fig. 7A to 7D, the alarm processing unit 105 can cause the display unit 111 to display any one of "normal display" (in the case where the tire air pressure is not reduced and the tire is not punctured), "air pressure reduction", and "puncture (air leakage)". In addition, the alarm processing unit 105 can cause the display unit 111 to display "notice high temperature".

Further, when "air pressure drop", "puncture (air leakage)" and "attention to high temperature" are displayed on the display unit 111, an alarm sound may be simultaneously output. The operation flow up to this display will be described later.

The volume value setting unit 107 sets a reference volume value Vs. Specifically, the volume value setting unit 107 sets the reference volume value Vs based on the tire air pressure P and the tire temperature T of a normal tire without a puncture.

That is, the volume value setting unit 107 calculates the reference volume value Vs from the tire air pressure P at the tire temperature T based on the tire air pressure P and the tire temperature T measured by the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50 RR. The reference volume value Vs can be calculated using the above (equation 1). In this case, the measured tire air pressure P and tire temperature T are applied to the reference tire air pressure Ps and reference tire temperature Ts of (equation 1).

Here, fig. 5B shows an example of the relationship between the set tire temperature Tr and the reference volume value Vs (when the reference tire air pressure Ps is 230 kPa). As shown in fig. 5B, the reference volume value Vs increases when the set tire temperature Tr rises, and decreases when the set tire temperature Tr falls.

Fig. 6 shows the relationship between the tire temperature T measured by the sensor and the tire air pressure P, the set tire temperature Tr, and the estimated tire air pressure Pr.

In fig. 6, the lateral direction (column direction) shows the measured tire temperature T (equivalent to the atmospheric temperature) or the set tire temperature Tr, and the vertical direction (row direction) shows the tire temperature Ti at the time of filling when air is filled so that the tire air pressure becomes the standard set air pressure (230 KPa). In addition, fig. 6 includes the set tire temperature Tr and the estimated tire air pressure Pr (P) shown in fig. 5A_t℃) An example of the relationship (when the reference tire temperature Ts is set to 15 ℃ and the reference tire air pressure Ps is set to 230 kPa).

As shown in fig. 6, when the tire temperature T (or the set tire temperature Tr) changes from the tire temperature Ti at the time of filling, the tire air pressure P (or the estimated tire air pressure Pr) based on the reference volume value Vs changes as shown in the respective cells of fig. 6. In an actual environment, the value of the tire air pressure indicated by the unit is used as the puncture determination threshold value P_THThe estimated tire pressure Pr of the reference.

For example, in the case where the tire temperature T falls to 5 ℃, as described above, the estimated tire air pressure Pr as a reference becomes 222.018 kPa. In contrast, for example, in the case where the tire temperature T falls to 30 ℃, the estimated tire air pressure Pr as a reference becomes 241.9279kPa (═ 273.15+ 30)/1.252826).

That is, if the measured tire temperature T is decreased from the set tire temperature Tr, the tire air pressure P is decreased, and if the measured tire temperature T is increased from the set tire temperature Tr, the tire air pressure P is increased.

The volume value setting unit 107 sets the reference volume value Vs based on the tables shown in fig. 5B and 6, and determines the relationship between the set reference volume value Vs and the tire temperature T (set tire temperature Tr).

Note that the volume value setting unit 107 may directly store the table shown in fig. 5B or 6, or may perform calculations using the above-described (expression 1) and (expression 2) at a time. As described above, the change in the tire temperature T and the change in the tire air pressure P may be obtained by an equation (a linear equation or the like).

The threshold setting unit 109 sets the puncture determination threshold P_TH. Specifically, the threshold value setting unit 109 sets the puncture determination threshold value P associated with the reference volume value Vs set by the volume value setting unit 107_TH。

More specifically, the threshold setting unit 109 sets the puncture determination threshold P based on the above-described (expression 4)_TH. Preferably, the puncture determination threshold value P_THIs set to be 0.8 or more and 0.95 or less of the estimated tire air pressure Pr (reference tire air pressure) associated with the set tire temperature Tr (reference tire temperature). In addition, it is preferable that the puncture determination threshold value P is_THIs higher than an air pressure drop threshold (for example, 0.8 below the standard set air pressure) for determining a drop in the tire air pressure P.

Thus, puncture can be determined earlier than a drop in tire air pressure P due to natural leakage.

The threshold setting unit 109 can also set an alarm threshold for the tire temperature T (tire temperature alarm threshold). The threshold setting unit 109 notifies the alarm processing unit 105 of the set tire temperature alarm threshold.

The display unit 111 executes the display shown in fig. 7A to 7D based on an instruction from the alarm processing unit 105. Specifically, the display unit 111 includes a display such as a liquid crystal panel, and displays the images shown in fig. 7A to 7D on the display. The display unit 111 may be a separate display or may be a display mounted on the vehicle 10 in common.

(3) Operation of a tire pressure monitoring system

Next, the operation of the tire air pressure monitoring system 30 will be described. Specifically, the initial setting operation of the tire air pressure monitoring system 30 and the puncture and tire air pressure drop detection operation will be described.

(3.1) initial setting operation

Fig. 3 shows a flow of the initial setting operation of the tire air pressure monitoring system 30. As shown in fig. 3, first, the operator (user) of the tire air pressure monitoring system 30 checks whether or not the tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR have an air leakage (S10). If an air leak is found, the operator stops the registration process and takes measures against the air leak (S20). Since the accurate reference volume value Vs may not be calculated when the air leakage occurs.

Next, the operator performs registration of the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50RR attached to each wheel position (FL, FR, RL, RR) (S30). Specifically, the sensor ID of each sensor is registered in the tire air pressure monitoring system 30 in association with the wheel position. Thereby, the tire air pressure monitoring system 30(TPMS main unit 100) can determine which wheel position the signal (data) output from each sensor is.

Further, the operator sets an air pressure drop threshold (S40). The air pressure drop threshold is generally set based on a standard set air pressure (for example, 230kPa) of the vehicle 10 (for example, 0.8 below the standard set air pressure).

Further, the operator sets the reference volume value Vs (S50). Specifically, the standard set air pressure of the vehicle 10 is taken as the estimated tire air pressure Pr, and the tire air pressure monitoring system 30 calculates the reference volume value Vs based on the estimated tire air pressure Pr and the tire temperature T measured by the tire air pressure monitoring system 30.

Further, if it is confirmed that there is no failure such as air leakage, the reference volume value Vs may also be calculated using the measured tire air pressure P and the tire temperature T.

Further, the tire air pressure monitoring system 30 sets the puncture determination formula (puncture determination threshold value P) according to the above (equation 3) based on the estimated tire air pressure Pr corresponding to the set reference volume value Vs_TH) (S60). For example, the estimated tire air pressure Pr is set to 230kPa, and the puncture determination threshold value P is set_THThe estimated tire air pressure Pr is set to 0.8 or more and 0.95 or less.

By completing the initial setting operation of the tire air pressure monitoring system 30, it is possible to detect a puncture and a drop in tire air pressure.

(3.2) detection actions of puncture and tire pressure drop

Fig. 4 shows a flow of the detection operation of detecting a puncture and a decrease in tire air pressure by the tire air pressure monitoring system 30. As shown in fig. 4, the tire air pressure monitoring system 30 acquires data indicating the tire air pressure P and the tire temperature T from the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50RR which are attached to each wheel (S105).

The tire air pressure monitoring system 30 determines whether the tire temperature T has reached a tire temperature alarm threshold value (S110). When the tire temperature T reaches the tire temperature alarm threshold, the tire air pressure monitoring system 30 determines that the temperature of the tire is increased, and displays an alarm of "notice of high temperature" (S170). For example, the tire air pressure monitoring system 30 displays an image as shown in fig. 7D on the display section 111.

The tire air pressure monitoring system 30 determines whether the tire air pressure P satisfies the puncture determination threshold P_TH(S120)。

When the tire air pressure P satisfies the puncture determination threshold P_THIn the case of (3), the tire air pressure monitoring system 30 determines that a failure has occurred, and displays a "puncture/failure" alarm (S160). For example, the tire air pressure monitoring system 30 displays an image as shown in fig. 7C on the display section 111.

When the tire air pressure P does not satisfy the puncture determination threshold value P_THIn the case of (1), the tire air pressure monitoring system 30 determines whether the tire air pressure P reaches an air pressure drop threshold value (S130). When the tire air pressure P does not reach the air pressure drop threshold value, the tire air pressure monitoring system 30 determines that it is normal and displays "OK" (S140). For example, the tire air pressure monitoring system 30 displays an image as shown in fig. 7A on the display section 111.

When the tire air pressure P reaches the air pressure drop threshold value, specifically, the tire air pressure monitoring system 30 determines whether the tire air pressure P is lower than the puncture determination threshold value P at the measured tire temperature T_THThat is, the tire air pressure P is determined whether or not the measured tire air pressure P reaches the puncture determination threshold value P based on the estimated tire air pressure Pr shown in fig. 6_TH(e.g. estimating tire pressure Pr)Any one of values of 0.8 or more and 0.95 or less).

When the tire air pressure P does not satisfy the puncture determination threshold value P_THIn the case of (3), the tire air pressure monitoring system 30 determines that inflation is necessary and displays an "inflation" alarm (S150). For example, the tire air pressure monitoring system 30 displays an image as shown in fig. 7B on the display section 111.

(3.3) correction of sensor measurement errors

Next, the correction of the measurement error of the sensor will be described. The sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50RR each have an inherent measurement error (instrument error). For improving the determination accuracy of puncture, it is preferable to correct errors in the temperature and pressure (internal pressure) measured by the sensor.

Fig. 8A and 8B show examples of measurement errors of the sensor. Specifically, fig. 8A shows an example of an error in the pressure value measured by the sensor (pressure sensor 53). Fig. 8B shows an example of an error of the temperature value measured by the sensor (temperature sensor 51).

As shown in fig. 8A and 8B, the sensor measurement values (pressure and temperature) include errors that have a tendency with respect to the ideal straight line (true value). That is, the reproducibility of such an error is confirmed for each sensor. Therefore, in the present embodiment, the tire air pressure monitoring system 30 (puncture determination unit 103) can correct the error for each of the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50RR using an equation of degree n approximating the value that the sensor measurement value is desirable to obtain, or using a table that correlates the sensor measurement value with the true value.

(4) Effect of action

According to the above embodiment, the following operational effects can be obtained. Specifically, the tire air pressure monitoring system 30 is based on the puncture determination threshold value P defined by the relationship between the tire air pressure P and the tire temperature T_THAnd determines whether the tire is punctured or not, the tire air pressure P and the tire temperature T being measured by the sensor 50FL, the sensor 50FR, the sensor 50RL and the sensor 50 RR. In addition, when it is determined that the tire is punctured, the puncture is more likely to be caused by the tireThe alarm generated by the drop in the air pressure P generates an alarm indicating that the tire is punctured earlier.

Further, in the present embodiment, the tire air pressure monitoring system 30 is based on the puncture determination threshold value P based on the reference volume value Vs calculated using the reference tire air pressure Ps and the reference tire temperature Ts_THTo determine whether the tire is punctured. More specifically, when the tire air pressure P measured by the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50RR satisfies the puncture determination threshold value P associated with the tire temperature T at the time of the measurement_THIn the case of (2), specifically, below the puncture determination threshold value P_THIn the case of (2), the tire air pressure monitoring system 30 determines that the tire is punctured.

That is, the puncture determination threshold value P based on the reference volume value Vs is not based on a simple decrease in the tire air pressure P but on the puncture determination threshold value P based on the reference volume value Vs_THTo determine whether or not the puncture is made, it is possible to accurately detect the puncture due to the leakage of the air filled in the tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR at an earlier stage, in contrast to the natural drop in the tire air pressure P (natural leakage of air) due to a change in the atmospheric temperature, or the like.

Such early and accurate puncture detection is based on the characteristic that the tire internal volume V is greatly changed by the occurrence of air leakage in the tire when the tire internal volume of a predetermined reference is set as the reference volume value Vs. That is, by correlating the amount of change in the tire internal volume V due to the puncture with the amount of change (decrease) in the tire air pressure P at the measured tire temperature T, it is possible to determine whether or not the puncture has occurred even if the amount of decrease in the tire air pressure P is slight.

On the other hand, the drop in the tire air pressure P due to natural leakage proceeds more slowly than puncturing, and therefore can be distinguished from the drop in the tire air pressure P due to air leakage.

In the present embodiment, when it is determined that the tire 20FL, the tire 20FR, the tire 20RL, and the tire 20RR (hereinafter, appropriately referred to as tires) are punctured, the tire air pressure monitoring system 30 can issue an alarm indicating that the tire is punctured, which is different from a drop in tire air pressure (air pressure drop threshold).

This can prompt the driver of the vehicle 10 or the like to repair the puncture early. In particular, in the case of a slow leak in which a projection such as a nail penetrates a tire and the air pressure gradually drops due to the leak, the driver tends to determine that the same as the natural leak is caused and to neglect the inspection of the tire, but the above-described means helps to avoid such a situation. Therefore, the tire can be prevented from being seriously damaged due to the failure to manage the slow air leakage.

In the present embodiment, the puncture determination threshold value P_THThe puncture determination threshold value P can be set to 0.8 or more and 0.95 or less of the estimated tire air pressure Pr (reference tire air pressure) associated with the set tire temperature Tr (reference tire temperature)_THIs higher than an air pressure drop threshold (for example, 0.8 below the standard set air pressure) for determining a drop in the tire air pressure P. Therefore, it is possible to detect the puncture of the tire earlier, separately from the decrease in the tire air pressure (air pressure decrease threshold).

In the present embodiment, the correction coefficient k of the tire temperature (specifically, the reference tire temperature Ts, the set tire temperature Tr) is used_TAnd a correction coefficient k of the tire air pressure (specifically, the reference tire air pressure Ps, the estimated tire air pressure Pr)_P. Specifically, the reference volume value Vs and the like can be calculated using the above-described (expression 1) to (expression 3).

Thus, a highly accurate reference volume value Vs or the like that can be used for determining puncture can be set in accordance with the measurement accuracy of the sensor and the type of tire.

In the present embodiment, the tire air pressure monitoring system 30 sets the reference volume value Vs based on the tire air pressure P and the tire temperature T of the tire that is not deflated, and sets the puncture determination threshold value P associated with the set reference volume value Vs_TH. Therefore, even in the case where the reference volume value Vs is calculated using the measured tire air pressure P and the tire temperature T, the accurate reference volume value Vs can be calculated.

In the present embodiment, the tire air pressure monitoring system 30 can beWhether or not the tire is flat can be determined based on a change in the tire air pressure P of the inflated tire after puncture repair or the like. That is, according to the flow of the puncture and tire air pressure drop detection operation shown in fig. 4, if the tire air pressure P of the inflated tire is higher than the puncture determination threshold value P_THThen it can be determined that the puncture has been repaired.

In particular, when a tire emergency puncture repair kit in which a tire is filled with a puncture repair liquid is used, it is possible to quickly determine whether or not a puncture hole is clogged with the puncture repair liquid. Therefore, it is not necessary to connect a compressor, an air pressure gauge, or the like to confirm the tire air pressure after filling the puncture repair liquid.

In the present embodiment, the tire air pressure monitoring system 30 can use the tire air pressure (tire air pressure P or estimated tire air pressure Pr (specifically Pr) after correcting the measurement errors of the sensor 50FL, the sensor 50FR, the sensor 50RL, and the sensor 50RR (or specifically, Pr)^x) And tire temperature (tire temperature T or set tire temperature Tr) after correcting a measurement error (instrument error) of the sensor, and determines that the tire is punctured.

Thus, even when the sensor has a fixed tolerance (instrument error), the puncture determination accuracy can be further improved.

(5) Other embodiments

While the present invention has been described with reference to the embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the descriptions, and various modifications and improvements can be made.

For example, in the above-described embodiment, although the TPMS main unit 100 is mounted on the vehicle 10, the functions implemented by the TPMS main unit 100 may be provided from the outside of the vehicle 10.

Fig. 8 is a schematic plan view and a schematic network configuration diagram of a vehicle 10A according to another embodiment. As shown in fig. 8, the vehicle 10A is provided with a communication device 150 instead of the TPMS main unit 100. The vehicle 10A belongs to a so-called interconnected car (connected car) that can be connected to the server computer 300 via a communication network. The communication device 150 may be configured as a part of a so-called telematics unit.

The communication device 150 is capable of performing wireless communication with the wireless base station 200. The communication device 150 is, for example, a wireless communication terminal connectable to a mobile communication network (LTE or the like).

The server computer 300 (database site) is provided on the communication network, and implements all or a part of the functions (the data acquisition unit 101, the puncture determination unit 103, the alarm processing unit 105, the volume value setting unit 107, and the threshold value setting unit 109) implemented by the TPMS main unit 100.

The program (software) for realizing the function may be stored in a downloadable state on a communication network, or may be provided in a form of being stored in a storage medium.

In the above-described embodiment, the vehicle 10 having four wheels is described as an example, but the present invention can be applied to various types of vehicles.

Fig. 9 is a schematic plan view of a vehicle 10B according to another embodiment. As shown in fig. 9, the structure of the rear wheel axle of the vehicle 10B is different when compared with the vehicle 10. Specifically, the rear wheel axle of the vehicle 10B is a so-called double tire, and a large vehicle such as a truck or a mine vehicle is mainly assumed as the vehicle 10B.

The vehicle 10B includes a tire 20RL used as a rear wheel_O(left outer rear wheel), tire 20RL_I(left inner rear wheel), tire 20RR_O(right outer rear wheel) and tire 20RR_I(right inner rear wheel). In addition, the tire 20RL_OTire 20RL_I20RR of tire_OAnd tire 20RR_IAre respectively provided with a sensor 50RL_OAnd a sensor 50RL_IAnd a sensor 50RR_OAnd a sensor 50RR_I。

The TPMS main unit 100 receives wireless signals from respective sensors of two front wheels and four rear wheels. The number of axles and wheels of the vehicle is not limited to the vehicle 10 and the vehicle 10B, and may be, for example, a tractor (tractor) having more axles and wheels.

As described above, although the embodiments of the present invention have been described, it should not be understood that the description and drawings constituting a part of the present disclosure serve to limit the present invention. Various alternatives, embodiments, and techniques will be apparent to those skilled in the art in light of this disclosure.

Industrial applicability

According to the tire air pressure monitoring system, the tire air pressure monitoring method, the tire air pressure monitoring program, and the vehicle, it is possible to detect a puncture due to air leakage filled in a tire more early and accurately, in a manner different from a natural decrease in air pressure due to a change in atmospheric temperature or the like, and therefore, the system, the method, the program, and the vehicle are useful.

Description of the reference numerals

10. 10A, 10B: a vehicle; 20FL, 20FR, 20RL, 20RR, 20RL_I、20RL_O、20RR_I、20RR_O: a tire; 30: a tire pressure monitoring system; 50FL, 50FR, 50RL, 50RR, 50RL_I、50RL_O、50RR_I、50RR_O: a sensor; 51: a temperature sensor; 53: a pressure sensor; 55: a sensor ID setting unit; 57: a transmitter; 90: a receiver; 100: a TPMS main unit; 101: a data acquisition unit; 103: a puncture determination unit; 105: an alarm processing unit; 107: a volume value setting unit; 109: a threshold setting unit; 111: a display unit; 150: a communication device; 200: a wireless base station; 300: a server computer.