JP2015202817A - Tire air pressure monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire air pressure monitoring system capable of providing proper information to a driver when an air pressure of a tire is lowered.SOLUTION: A tire air pressure sensor unit 3 is provided on every wheel 2 of a vehicle 1 and detects an air pressure of the wheel 2 respectively. A selection part of a tire air pressure monitoring unit 5, when detecting a predetermined fall of the air pressure of the wheel 2, selects the content of necessary information from among a plurality of information patterns in accordance with a change of vehicle characteristics supposed dependent on which wheel 2 causes the lowering of the air pressure. Therein, the tire air pressure monitoring unit 5 informs an indicator 4 of the content of information selected by the selection part.

Description

  The present invention relates to a tire pressure monitoring system.

  Since a decrease in tire air pressure leads to a decrease in vehicle motion characteristics, if the driver is notified of the decrease in air pressure, it can contribute to preventive safety of the vehicle.

  For example, in Patent Document 1, as notification means to the driver when the air pressure decreases, first notification means for notifying the driver which wheel is the wheel whose tire air pressure has decreased, and the traveling state of the vehicle It is disclosed that the first notification means and the second notification means are switched according to the traveling state of the vehicle, including a second notification means that notifies the driver according to whether the vehicle is stopped or traveling.

  Here, for example, when the air pressure of the right front tire of the vehicle decreases, the first notification means turns on the right front tire portion of the display, and issues a message “Migimaeno Tire No Kukukitsuga Takeshi Taishimasu” with the voice synthesizer. . In addition, the second notification means displays a message “Speed” when the vehicle is running, and “Service Station Ariha Gas Station Hekinasai” when the vehicle is running under low air pressure. Each emits.

Japanese Patent Publication No. 1-26885

However, in order to achieve further preventive safety of the vehicle, the notification means disclosed in Patent Document 1 is insufficient.
That is, in the first notification means, the driver can know which wheel has the reduced tire air pressure. However, what kind of points should be paid attention to when compared with the case where the air pressure of all the wheels is normal before the wheel can be refilled with air pressure after receiving the notification. The first notification means has a problem that the driver does not know.

  In addition, the second notification means can know the point that the driver should be aware of during driving (do not overspeed) and the action to be taken (go to a service station or a gas station). However, these precautions and actions to be taken are not always the same when the tire pressure drops. That is, the driver's points of caution and actions to be taken vary depending on which wheel the tire pressure is reduced to, and the second notification means that the driver knows that point. There is a bug that cannot be done.

  Accordingly, an object of the present invention is to enable appropriate notification to the driver when the tire air pressure decreases.

One aspect of the present invention is provided for each wheel of a vehicle, and a detection unit that detects the air pressure of the wheel, and a wheel in which the air pressure decreases when the detection unit detects a predetermined decrease in the air pressure of the wheel. In accordance with a change in vehicle characteristics assumed depending on which one is, a selection unit that selects necessary notification contents from a plurality of notification patterns, and notification is performed with the notification contents selected by the selection unit A tire air pressure monitoring system including an informing unit.
According to the present invention, it is possible to perform necessary notification according to a change in vehicle characteristics assumed depending on which wheel has a reduced air pressure.

In the present invention, the notification unit may perform the notification when the detection unit detects a decrease in the air pressure in at least two of the four wheels provided on the vehicle. Good.
According to the present invention, unnecessary notification can be prevented by performing necessary notification in the case of a decrease in air pressure of two or more wheels, which generally has a large change in vehicle characteristics.

Further, in the above invention, the selection unit may be configured such that an imbalance of air pressure has occurred in the left and right wheels of the vehicle due to a decrease in the air pressure by the detection unit, or an imbalance of air pressure in the front and rear wheels of the vehicle. Different notification contents may be selected from the plurality of notification patterns depending on whether the balance has occurred.
According to the present invention, the vehicle characteristics are different depending on whether the wheel that has detected the drop in air pressure is on the left or right side, or on the front or rear side. It can be carried out.

  According to the present invention, it is possible to appropriately notify the driver when the tire air pressure decreases.

1 is a diagram showing a system configuration of a vehicle equipped with a tire pressure monitoring system according to an embodiment of the present invention. It is a block diagram which shows the electrical connection of the tire pressure sensor unit of the tire pressure monitoring system which concerns on one Embodiment of this invention. It is a block diagram which shows the electrical connection of the tire pressure monitoring unit of the tire pressure monitoring system which concerns on one Embodiment of this invention. It is a flowchart explaining the process which the tire pressure monitoring unit of the tire pressure monitoring system which concerns on one Embodiment of this invention performs.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a system configuration of a vehicle equipped with a tire pressure monitoring system according to the present embodiment will be described. FIG. 1 is a diagram showing a system configuration of a vehicle equipped with a tire pressure monitoring system according to the present embodiment. In FIG. 1, the front, rear, left and right directions of the vehicle 1 are indicated by arrows.

In FIG. 1, a vehicle 1 is a four-wheel vehicle equipped with four wheels 2 including a right front wheel 2FR, a left front wheel 2FL, a right rear wheel 2RR, and a left rear wheel 2RL. In addition, tire air pressure sensor units 3 (3FR, 3FL, 3RR, 3RL) serving as a detection unit for detecting tire air pressure are mounted on the tires of the respective wheels 2 (2FR, 2FL, 2RR, 2RL).
A tire pressure monitoring system 10 is mounted on the vehicle 1, and the tire pressure monitoring system 10 includes a tire pressure sensor unit 3, an indicator 4, and a tire pressure monitoring unit 5.

  The schematic outer shape of the tire pressure sensor unit 3 is shown in an enlarged perspective view in the upper right of FIG. Since the tire pressure sensor unit 3 is attached to the rim surface of the wheel 2, the lower surface of the tire pressure sensor unit 3 (the lower surface in the enlarged perspective view on the upper right in FIG. 1) is curved so as to be in close contact with the rim surface. Further, the upper surface of the tire pressure sensor unit 3 (the upper surface in the enlarged perspective view on the upper right in FIG. 1) is provided with an air hole 38 directly connected to the tire valve 37 and a sensor hole 39 communicating with a sensor installation space (not shown). The tire pressure sensor unit 3 includes a tire pressure sensor 34 and an acceleration sensor (centrifugal force sensor) 36 (FIG. 2) in the sensor installation space. The tire air pressure sensor unit 3 detects the air pressure and acceleration (centrifugal force) in the tire, and the detected data is transmitted to the tire air pressure monitoring unit 5 via the radio signal transmitting device 32 and the antenna 33 (FIG. 2). Send to.

  The vehicle 1 is equipped with a tire pressure monitoring unit 5, and the tire pressure monitoring unit 5 receives a radio signal transmitted from the tire pressure sensor unit 3 mounted on each wheel 2 via the antenna 51. The tire pressure data and acceleration data are acquired. Then, it is possible to detect a decrease in tire air pressure by comparing the tire air pressure data with a predetermined value.

  The acceleration sensor 36 (FIG. 2) provided in the tire pressure sensor unit 3 detects the acceleration caused by the centrifugal force during traveling, and provides the acceleration data to the tire pressure sensor unit 3 as will be described in detail later. The transmission frequency of the radio signal (tire pressure data) transmitted from the microprocessor 31 to the tire pressure monitoring unit 5 is controlled. That is, the tire pressure sensor unit 3 transmits tire pressure data to the tire pressure monitoring unit 5 at a transmission frequency corresponding to the acceleration (according to the speed of the vehicle 1). Alternatively, the tire pressure sensor unit 3 determines the transmission timing of tire pressure data to be transmitted to the tire pressure monitoring unit 5 when the acceleration becomes equal to or higher than a predetermined value (when the speed of the vehicle 1 reaches a predetermined vehicle speed). Speed up. For example, when the vehicle 1 is at a high speed, the transmission frequency of tire pressure data transmitted from the tire pressure sensor unit 3 is increased. The control based on the acceleration is not an essential configuration for carrying out the present invention, and can be omitted.

  FIG. 2 is a block diagram showing electrical connection of the tire pressure sensor unit 3 shown in FIG. The tire pressure sensor unit 3 includes a tire pressure sensor 34, a temperature sensor 35, an acceleration sensor 36, an IC (Integrated Circuit) 30a, and the like as an ASIC (Application Specific Integrated Circuit) 30 of a custom chip. Further, a battery 31 a serving as a power source for the tire pressure sensor unit 3, a radio signal transmission device 32 for transmitting a signal from the tire pressure sensor 34 to the tire pressure monitoring unit 5, and an antenna 33 are also mounted.

  The tire pressure sensor unit 3 includes a microprocessor 31 having an arithmetic processing unit 311 and a memory unit 312. The microprocessor 31 includes sensors such as a tire pressure sensor 34, a temperature sensor 35, and an acceleration sensor 36. In addition, a wireless signal transmission device 32 is connected. The memory unit 312 of the microprocessor 31 usually includes a RAM (Random Access Memory) and a ROM (Read Only Memory) including an EEPROM (Electrically Erasable and Programmable Read Only Memory) such as a flash memory. A sensor ID storage unit 313 is provided in a partial area of the ROM, and sensor IDs for individually identifying the four tire pressure sensor units 3FR, 3FL, 3RR, and 3RL are stored.

  Further, the microprocessor 31 has a built-in timer (not shown). For example, the microprocessor 31 operates every 10 seconds, and the tire pressure and temperature detected by sensors such as the tire pressure sensor 34, the temperature sensor 35, and the acceleration sensor 36 are detected. Acquire data such as acceleration. Then, the microprocessor 31 attaches the sensor ID read from the sensor ID storage unit 313 to the acquired data such as tire pressure, temperature, acceleration, etc., generates data of the tire pressure sensor unit 3, and transmits a radio signal. Data of the tire pressure sensor unit 3 is transmitted to the tire pressure monitoring unit 5 via the device 32 and the antenna 33.

Further, when the acceleration data from the acceleration sensor 36 is not less than a predetermined value (that is, when the vehicle speed is not less than the predetermined speed), the microprocessor 31 includes the tire pressure sensor unit 3 including the tire pressure data. Increase the frequency of data transmission.
Further, the microprocessor 31 increases the data transmission frequency of the tire pressure sensor unit 3 including the tire pressure data in proportion to the magnitude of the acceleration from the acceleration sensor 36 (that is, in proportion to the vehicle speed). It can also be.

  The indicator 4 is provided on an instrument panel or the like of the vehicle 1, and can display various messages with characters, figures, symbols, and the like according to instructions from the tire pressure monitoring unit 5.

  FIG. 3 is a block diagram showing electrical connection of the tire pressure monitoring unit 5 shown in FIG. The tire pressure monitoring unit 5 is a control device including a microprocessor, an ASIC, and the like, and includes a radio signal receiving device 52, a notification pattern storage unit 53, a selection unit 54, and a notification control unit 55. The radio signal receiving device 52 receives data transmitted from the radio signal transmitting device 32 of each tire pressure sensor unit 3 by the antenna 51. The notification pattern storage unit 53 stores a plurality of notification patterns for notifying the driver of messages necessary for the indicator 4. When the tire pressure sensor unit 3 detects a predetermined decrease in tire air pressure, the selection unit 54 stores a notification pattern according to a change in vehicle characteristics assumed depending on which wheel 2 has the decreased air pressure. The necessary notification content is selected from the plurality of notification patterns of the unit 53. The notification control unit 55 controls the indicator 4 so as to notify the driver with the content of the notification selected by the selection unit 54. Further, the notification control unit 55 and the indicator 4 realize a notification unit.

  The tire pressure sensor unit 3 attaches a unique sensor ID stored in the sensor ID storage unit 313 to tire pressure data transmitted by itself. On the other hand, the tire pressure monitoring unit 5 stores in advance, for example, what sensor ID of the tire pressure sensor unit 3 is attached to the right front wheel 2FR. For this reason, the tire pressure monitoring unit 5 that has received the data relating to the tire pressure can identify which wheel 2 the tire pressure sensor unit 3 on which the received tire pressure data is attached.

  Next, processing executed by the tire pressure monitoring unit 5 will be described in detail. FIG. 4 is a flowchart for explaining processing executed by the tire pressure monitoring unit 5. First, when data is received from each tire pressure sensor unit 3 via the wireless signal receiving device 52 (Yes in S1), the selection unit 54 has tires in which the air pressure is equal to or less than a reference threshold value in the four wheels. It is determined whether or not exists (S2). When there is a tire whose air pressure is equal to or lower than a reference threshold (Yes in S2), the selection unit 54 determines whether the number of tires whose air pressure is equal to or lower than the threshold is two or more of four. (S3). When the number of the tires is two or more (Yes in S3), the selection unit 54 responds to an assumed change in vehicle characteristics depending on which tire the tire whose air pressure is equal to or less than a threshold value. The content of the notification is selected from a plurality of notification patterns stored in the notification pattern storage unit 53 (S4). Then, the notification control unit 55 displays the notification content on the indicator 4 with the selected notification content (S5).

On the other hand, if there are no tires whose air pressure is equal to or less than the threshold value or the number of tires is one (No in S2, No in S3), the notification (S5) is not performed.
In addition, although the example which performs alerting | reporting of the message to a driver | operator by the display on the indicator 4 is shown here, you may make it alert | report to a driver | operator by making a voice announcement, You may make it use a display and the announcement by an audio | voice together.

Next, the contents of the processes of S4 and S5 will be described using a specific example. First, the tire air pressures of the wheels 2FR, 2FL, 2RR, 2RL detected as described above are set as ΔP _FR , ΔP _FL , ΔP _RR , ΔP _RL , respectively.

First, when it is the front wheels 2FR and 2FL (or the rear wheels 2RR and 2RL) that the air pressure is equal to or lower than the threshold value, the rear wheels 2RR and 2RL (or the front wheels 2FR and 2FL) If there is a decrease in tire air pressure that exceeds a predetermined value, that is, “(ΔP _RR + ΔP _RL ) / 2− (ΔP _FR + ΔP _FL ) / 2> P _k (P _k is a predetermined reference value)”, Or, consider the case where “(ΔP _FR + ΔP _FL ) / 2− (ΔP _RR + ΔP _RL ) / 2> P _k ”. The change in the vehicle characteristics assumed in this case may cause a reduction in braking force (it cannot stop at the braking distance expected by the driver). Therefore, in this case, in S4, the content of the notification that alerts the decrease in braking force as the assumed change in vehicle characteristics is selected from the plurality of notification patterns stored in the notification pattern storage unit 53. select. That is, the contents of the notification such as “attention to the vehicle” and “allow a margin in the inter-vehicle distance”. In S5, this content is notified by display on the indicator 4 or the like.

As another example, when it is the right wheel 2FR, 2RR (or the left wheel 2FL, 2RL) that the air pressure is equal to or lower than the threshold value, the left wheel 2FL, 2RL (or the right wheel 2FR, 2), when the tire air pressure drops below a predetermined value, that is, “(ΔP _FR + ΔP _RR ) / 2− (ΔP _FL + ΔP _RL ) / 2> P _k ” or “(ΔP _FL Consider the case of + ΔP _RL ) / 2− (ΔP _FR + ΔP _RR ) / 2> P _k ″. The change in the vehicle characteristics assumed in this case may cause a decrease in turning force (cornering performance). Therefore, in this case, in S4, the content of the notification that alerts the decrease in the turning force as the assumed change in vehicle characteristics is selected from the plurality of notification patterns stored in the notification pattern storage unit 53. select. That is, the contents of the notification such as “careful about the curve” and “early decelerate”. In S5, this content is notified by display on the indicator 4 or the like.

  According to the tire air pressure monitoring system 10 of the present embodiment described above, a driver can be notified of a necessary message according to a change in vehicle characteristics that is assumed depending on which tire has a decreased air pressure. Yes (S4, S5). Therefore, according to the tire pressure monitoring system 10, when the tire pressure drops, an appropriate message can be notified to the driver.

In this case, if only one tire has a reduced air pressure (No in S3), the tire air pressure monitoring system 10 does not notify the driver of a necessary message.
That is, the change in vehicle characteristics is often small as long as only one of the four tires has a reduced air pressure. Therefore, the tire pressure monitoring system 10 can prevent unnecessary notification when there is only one tire whose air pressure has decreased. Of course, the notification may be made as described above even when there is only one tire whose air pressure has decreased.

  Furthermore, the change in vehicle characteristics varies depending on whether an air pressure imbalance occurs in the tires of the left and right wheels 2 of the vehicle 1 or an air pressure imbalance occurs in the tires of the wheels 2 on the front and rear sides of the vehicle 1. Therefore, as described above, in the tire pressure monitoring system 10, an air pressure imbalance has occurred in the tires of the left and right wheels 2 of the vehicle 1, or an air pressure imbalance has occurred in the tires of the wheels 2 before and after the vehicle 1. Depending on whether or not, different messages suitable for each case can be notified.

In the above-described embodiment, a tire pressure monitoring system (TPMS: Tire Pressure Monitoring System) in which the tire pressure sensor unit 3 autonomously determines the transmission timing of tire pressure data has been described as an example. The present invention can also be applied to a type of TPMS in which the tire pressure sensor unit 3 transmits tire pressure based on a signal (for example, a signal generated by an initiator).
In the above-described embodiment, an example of a direct TPMS using the tire pressure sensor 34 that directly measures the air pressure of the air chamber has been described. From the wheel speed of each wheel 2 obtained by the wheel speed sensor, The present invention can also be applied to an indirect TPMS that calculates the dynamic load radius, resonance frequency, and the like of the wheel 2 and estimates the air pressure from these values.
That is, there is no particular limitation on the TPMS format to which the present invention is applied.

Note that the present invention can also be applied to a case where the wheel (tire) 2 with reduced air pressure cannot identify any of the four wheels.
Further, for example, based on the difference between the previous air pressure and the current air pressure, a response to the case where the air pressure is rapidly decreasing is stored in the notification pattern storage unit 53, and the selection unit 54 An appropriate message may be selected from the notification pattern storage unit 53 using the air pressure decrease speed as a key.

1 vehicle 3 tire pressure sensor unit (detection unit)
10 Tire Pressure Monitoring System 54 Selection Unit 55 Notification Control Unit (Notification Unit)

Claims (3)

A detection unit that is provided for each wheel of the vehicle and detects the air pressure of the wheel;
When the detection unit detects a predetermined decrease in the air pressure of the wheel, a necessary notification is made from among a plurality of notification patterns according to a change in vehicle characteristics assumed depending on which wheel has the decreased air pressure. A selection section for selecting the contents of
A tire pressure monitoring system, comprising: a notification unit that performs notification based on the notification content selected by the selection unit.   The said alerting | reporting part performs the said alerting | reporting, when the said detection part detects the fall of the said air pressure by the at least 2 wheel of the said 4 wheels provided in the said vehicle. Tire pressure monitoring system.   The selection unit is configured to determine whether an air pressure imbalance has occurred in the left and right wheels of the vehicle or an air pressure imbalance has occurred in the front and rear wheels of the vehicle due to the decrease in the air pressure. The tire pressure monitoring system according to claim 1, wherein different notification contents are selected from the plurality of notification patterns.

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