JP6922490B2 - Control and tire monitoring system - Google Patents

Description

The present disclosure relates to control devices and tire monitoring systems.

Conventionally, a tire pressure monitoring system (TPMS) that monitors the air pressure of automobile tires and warns of a decrease in air pressure has been known.

The permissible load (load capacity) of the tire corresponding to the air pressure of the tire is predetermined. The permissible load of a tire must be greater than or equal to the load applied to the tire for safe driving of the vehicle.

Japanese Unexamined Patent Publication No. 2005-88726

By the way, the weight of the sprung member supported by the spring of the suspension (referred to as the sprung weight) is obtained, for example, by the relational expression between the spring constant and the sprung weight. The spring weight varies depending on, for example, the load capacity.

The unsprung weight and the unsprung weight (the weight of the parts arranged below the spring) are added to the tire. The permissible load of a tire varies not only with the tire size but also with its air pressure, and when it is smaller than the load applied to the tire, the driver is notified of the inability to drive. After the notification, the weight on the spring (for example, the load capacity) is reduced, so that even if the vehicle can travel, it is erroneously determined that the vehicle cannot travel. This is because the tire pressure and the spring weight are managed separately.

An object of the present disclosure is to provide a control device and a tire monitoring system capable of accurately determining a tire condition.

The control device of the present disclosure is
An input unit that inputs the tire pressure of the axle detected by the air pressure sensor and the axle load of the axle,
A comparison unit that compares the allowable load of the tire corresponding to the detected tire pressure with the axle load of the axle and outputs the comparison result.
To be equipped.

The control device of the present disclosure is
An input section where the tire temperature detected by the temperature sensor is input, and
A second warning output unit that outputs a signal instructing a warning when the detected temperature exceeds a predetermined allowable temperature, and
To be equipped.

The tire monitoring system of the present disclosure is
An air pressure sensor that detects the tire pressure on the axle, and
A comparison unit that compares the allowable load of the tire corresponding to the detected tire pressure with the axle load of the axle and outputs the comparison result.
To be equipped.

According to the present disclosure, it is possible to accurately determine the condition of the tire.

A block diagram showing an example of the configuration of the tire monitoring system according to the embodiment of the present disclosure. Graph showing the relationship between tire pressure and elapsed time A graph showing the relationship between an index showing tire life and elapsed time Flowchart showing tire pressure monitoring process

Hereinafter, the tire monitoring system 1 according to the embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of the tire monitoring system 1 according to the present embodiment.

As shown in FIG. 1, the tire monitoring system 1 includes an air pressure sensor 12, a temperature sensor 14, a vehicle speed acquisition unit 16, a axle load acquisition unit 18, a calculation unit 20, a storage unit 30, and a notification unit 40. The calculation unit 20 has components of a comparison unit 21, a rate of change calculation unit 22, an estimation unit 23, an index integration unit 24, and a warning output unit 25.

The vehicle in this embodiment is, for example, a four-wheeled vehicle. The front right wheel, front left wheel, rear right wheel, and rear left wheel of the four-wheeled vehicle are suspended from the vehicle body by suspension. In the following description, the tire air pressure and the axle load of the axle refer to the tire air pressure of each wheel and the axle load of the axle.

The vehicle is provided with an engine control unit 10 (ECU) (corresponding to the "control device" of the present invention) that comprehensively controls the operation control of the engine when the auxiliary device is used. In this embodiment, the functions of each component of the calculation unit 20 are realized by the ECU 10 executing the control program.

The air pressure sensor 12 and the temperature sensor 14 are mounted inside the tire or wheel.

The air pressure sensor 12 detects the tire pressure at predetermined time intervals. The detected air pressure is input to the ECU 10. The storage unit 30 stores the air pressure as history information. The allowable load of the tire corresponding to the air pressure of the tire is predetermined. The storage unit 30 stores an allowable load corresponding to the air pressure.

The temperature sensor 14 detects the temperature of the tire at predetermined time intervals. The detected temperature is input to the ECU 10. The storage unit 30 stores the temperature as history information.

Vehicle speed information is input to the ECU 10 from the vehicle speed sensor. The vehicle speed acquisition unit 16 acquires vehicle speed information. The vehicle speed acquisition unit 16 may acquire vehicle speed information used by another vehicle control device (not shown).

The axle load of the axle is input to the ECU 10. The axle load acquisition unit 18 acquires the axle load of the axle. The axial weight is, for example, the total weight of the weight of the sprung member supported by the spring of the suspension (unsprung weight) and the weight of the part provided below the spring (called the unsprung weight, which is constant). Is. The axle load varies depending on the spring weight (for example, load capacity). The on-spring weight is obtained, for example, by the relational expression between the spring constant and the on-spring weight.

The comparison unit 21 compares the allowable load of the tire with the axle load. The comparison unit 21 outputs a comparison result between the allowable load and the axle load. The notification unit 40 has a display device and an alarm buzzer. The ECU 10 causes the notification unit 40 to display the comparison result. Specifically, the ECU 10 causes the notification unit 40 to display a warning when the allowable load is smaller than the axle load. In this case, the ECU 10 may generate a warning sound in the notification unit 40.

The rate of change calculation unit 22 calculates the rate of change indicating the amount of change in the tire pressure per unit time.

FIG. 2 shows the history information of the air pressure plotted on the coordinates. The rate of change calculation unit 22 obtains an approximate straight line of the linear function from the history information of the air pressure by a known method (for example, the least squares method). The rate of change calculation unit 22 calculates the slope of the approximate straight line as the rate of change in air pressure.

The storage unit 30 stores a predetermined lower limit value. Here, the lower limit value is a numerical value meaning that the reliability of the tire is lowered due to deformation or heat generation of the tire, and there is a high possibility that a defect will occur in some cases.

The estimation unit 23 estimates the time until the tire pressure reaches the lower limit value. Specifically, the estimation unit 23 obtains the intersection of the approximate straight line and the lower limit value, and calculates the time difference between the obtained intersection and the current time. The ECU 10 causes the notification unit 40 to display the time difference.

The remaining life of a tire varies depending on the load on the tire.
The tire life LT (load) is expressed by the following formula (1).
LT = W × S (1)
Here, W indicates the axle load and S indicates the vehicle speed.

The index integrating unit 24 reads the axle load W and the vehicle speed S at predetermined time intervals. The index integrating unit 24 calculates an index indicating the tire life LT by the equation (1) based on the axle load W and the vehicle speed S.

The index integration unit 24 integrates the index with the elapsed time. In FIG. 3, the index represented on the coordinates and the integrated value I of the index are represented by the area of the hatched area.

The warning output unit 25 outputs a signal instructing a warning when the integrated value of the index exceeds a predetermined threshold value. Here, the predetermined threshold value is a numerical value meaning that the driving is an operation that increases the load on the tire. If such operation is continued, there is a high possibility that a problem such as a burst will occur. The ECU 10 causes the notification unit 40 to display a warning (for example, the danger of burst).

Next, the tire pressure monitoring process will be described with reference to FIG. FIG. 4 is a flowchart showing the tire pressure monitoring process. This process is started, for example, when the vehicle is shipped.

First, in step S100, the comparison unit 21 acquires the tire pressure detected by the air pressure sensor 12.

In step S110, the comparison unit 21 reads the axle load from the axle load acquisition unit 18.

In step S120, the comparison unit 21 reads the allowable load of the tire corresponding to the tire pressure from the storage unit 30.

In step S130, the comparison unit 21 compares the axle load with the allowable load and outputs the comparison result.

When the allowable load is smaller than the axle load (step S130: YES), the ECU 10 causes the notification unit 40 to display a warning (step S140). After that, the process ends.

When the allowable load is equal to or greater than the axle load (step S130: NO), the ECU 10 ends the process.

<Effect of this embodiment>
As described above, the tire monitoring system 1 according to the present embodiment compares and compares the air pressure sensor 12 that detects the tire pressure of the axle with the allowable load of the tire corresponding to the air pressure and the axle load of the axle. It is provided with a comparison unit 21 that outputs a result. As a result, the user can accurately determine whether or not to drive based on the comparison result.

Further, according to the tire monitoring system 1 according to the present embodiment, the change rate calculation unit 22 that calculates the change rate indicating the amount of change in the air pressure with respect to the elapsed time based on the history information of the air pressure, and the air pressure based on the change rate. Is provided with an estimation unit 23 that estimates the time until the tire reaches a predetermined lower limit value. As a result, the user can make an accurate decision for safe driving of the vehicle based on the predicted information that the reliability of the tire will decrease after several hours from the present time and that a failure is likely to occur in some cases. It can be carried out.

Further, according to the tire monitoring system 1 according to the present embodiment, the index integrating unit 24 that calculates an index indicating the tire life based on the axle load and the vehicle speed and integrates the calculated index, and the integrated value of the index are It is provided with a warning output unit 25 that outputs a signal instructing a warning when a predetermined threshold value is exceeded. The warning allows the user to make an accurate decision to switch to, for example, driving that does not increase the load on the tires for safe driving of the vehicle.

In the above embodiment, the warning output unit 25 outputs a signal instructing a warning when the integrated value of the index exceeds a predetermined threshold value. Not limited to this, a temperature sensor 14 for detecting the temperature of the tire may be provided, and the warning output unit 25 may output a signal instructing a warning when the temperature of the tire exceeds a predetermined allowable temperature. .. As a result, the user can accurately make a judgment for safe driving of the vehicle based on the information that the temperature of the tire has risen beyond the permissible temperature.

Further, the warning output unit 25 may output a signal instructing a warning when the integrated value of the index exceeds a predetermined threshold value and when the tire temperature exceeds a predetermined allowable temperature. good. As a result, the accuracy of information that means that there is a high possibility that a problem such as a burst will occur can be improved.

Further, in the above embodiment, the warning output unit 25 outputs a signal instructing a warning when the integrated value of the index exceeds a predetermined threshold value. Not limited to this, the warning output unit 25 may output a signal instructing a warning when the time change of the index exceeds a predetermined allowable value. As a result, the user can quickly make a decision for safe driving of the vehicle.

Further, a transmitter is provided on the tire side, a receiver is provided on the ECU 10 side, and the detection signal detected by the air pressure sensor 12 on the tire side is transmitted from the transmitter to the receiver on the ECU 10 side by wireless communication method. It may be configured.

The tire monitoring system of the present disclosure is useful as a driving support device that is required to support the vehicle so that it can run safely through various information related to the condition of the tire.

1 Tire monitoring system 10 ECU
12 Pneumatic sensor 14 Temperature sensor 16 Vehicle speed acquisition unit 18 Axis load acquisition unit 20 Calculation unit 21 Comparison unit 22 Change rate calculation unit 23 Estimate unit 24 Index integration unit 25 Warning output unit 30 Storage unit 40 Notification unit

Claims (5)

An input unit that inputs the tire pressure of the axle detected by the air pressure sensor and the axle load of the axle,
A comparison unit that compares the allowable load of the tire corresponding to the detected tire pressure with the axle load of the axle and outputs the comparison result.
A control device. Based on the detected history information of the air pressure, a change rate calculation unit that calculates a change rate indicating the amount of change of the air pressure per unit time, and a change rate calculation unit.
An estimation unit that estimates the time until the air pressure reaches a predetermined lower limit value based on the rate of change.
The control device according to claim 1. The vehicle speed is input to the input unit,
An index integrating unit that calculates an index indicating the life of the tire based on the axle load and the vehicle speed and integrates the calculated index.
A first warning output unit that outputs a signal instructing a warning when the integrated value obtained by integrating the indexes exceeds a predetermined threshold value.
The control device according to claim 1 or 2. The tire temperature detected by the temperature sensor is input to the input unit.
The first warning output unit outputs a signal instructing a warning when the integrated value exceeds a predetermined threshold value and the detected temperature exceeds a predetermined allowable temperature. Item 3. The control device according to item 3. An air pressure sensor that detects the tire pressure on the axle, and
A comparison unit that compares the allowable load of the tire corresponding to the detected tire pressure with the axle load of the axle and outputs the comparison result.
A tire monitoring system equipped with.

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