WO2012160780A1

WO2012160780A1 - Tire pressure detection device

Info

Publication number: WO2012160780A1
Application number: PCT/JP2012/003202
Authority: WO
Inventors: 朋宏久野; 渡部　宣哉
Original assignee: 株式会社デンソー
Priority date: 2011-05-20
Filing date: 2012-05-16
Publication date: 2012-11-29
Also published as: CN103547464B; JP2013006588A; CN103547464A

Abstract

A tire pressure detection device, wherein transmitters (2a-2d) attached to wheels (7a-7d), respectively, monitor tire pressure and transmit abnormality information to a control unit (4) on the vehicle body (8) side when the tire pressure has dropped. The transmitters (2a-2d) each monitor the tire pressure with a sampling period shorter than a regular transmission period. Consequently, compared to when the tire pressure abnormality is determined by receivers on the vehicle body side, the tire pressure can be monitored with a shorter period. Moreover, since the tire pressure is monitored with the shorter sampling period, when the tire pressure has dropped, both rapidly and slowly, the pressure drop can be immediately transmitted to the control unit (4), and transmitted to a driver via a warning display (6). Therefore, even when the tire pressure has slowly dropped, a warning can be given in a shorter time after the occurrence of abnormality.

Description

Tire pressure detector

Cross-reference of related applications

The present disclosure is based on Japanese application number 2011-113345 filed on May 20, 2011 and Japanese application number 2012-101024 filed on April 26, 2012. Is used.

The present disclosure directly attaches a transmitter equipped with a pressure sensor to a wheel to which a tire is attached, transmits a detection result of the pressure sensor from the transmitter, and receives it by a receiver attached to the vehicle body side. The present invention relates to a direct tire pressure detecting device for detecting tire pressure.

Conventionally, a direct type tire pressure detecting device is known. In this type of tire pressure detecting device, a transmitter equipped with a sensing unit such as a pressure sensor is directly attached to a wheel to which a tire is attached. In addition, an antenna and a receiver are provided on the vehicle body side. When the detection result in the sensing unit is transmitted from the transmitter, the detection result is received by the receiver via the antenna, and the tire pressure is detected. Is done.

In addition, as a conventional tire pressure detecting device, when a transmitter transmits a tire pressure detection result at a predetermined transmission cycle to the receiver side at a predetermined transmission cycle, and the transmitter detects a sudden decrease in tire pressure. In some cases, the periodic transmission frequency is increased (for example, Patent Document 1). As described above, by increasing the transmission frequency of the regular transmission, the receiver side can be accurately informed that the tire air pressure has suddenly decreased.

However, when the frequency of periodic transmission is increased when the tire pressure suddenly decreases as in the conventional case, it is possible to cope with the rapid decrease in tire pressure, but it is difficult to cope with the slow decrease. That is, with regard to sudden pressure reduction, the transmission rate of regular transmission can be increased because the tire air pressure decrease gradient is greater than or equal to a predetermined threshold value, but in the case of slow pressure reduction, the tire air pressure decrease gradient is less than the predetermined threshold value. The transmission frequency of regular transmission does not increase. For this reason, it is difficult to immediately detect a decrease in tire air pressure during slow pressure reduction.

Further, in the case of a conventional tire pressure detecting device, although measures such as increasing the transmission frequency of periodic transmission are performed on the transmitter side, the tire pressure is determined based on information transmitted from the transmitter to the receiver. It will be. For this reason, if the transmission cycle of the regular transmission is shortened so that the tire pressure can be measured more finely, the number of transmissions per unit time increases, leading to a reduction in battery life. On the transmitter side, power consumption is particularly large during data transmission, and increasing the number of transmissions per unit time is disadvantageous from the viewpoint of battery life. In particular, if the transmission frequency is increased as in the case of sudden depressurization at all times, the battery life will be further reduced.

Japanese Patent Laid-Open No. 11-334328

In view of the above points, it is an object of the present disclosure to provide a tire air pressure detection device that can provide a warning in a shorter time from occurrence of an abnormality even when the tire air pressure is suddenly reduced and gradually reduced.

According to one aspect of the present disclosure, the transmitter monitors the tire air pressure acquired by the sensing unit, and transmits abnormality information when the tire air pressure decreases, thereby notifying the reception unit and receiving unit. The tire pressure detecting device is configured to output a warning information indicating a tire pressure drop alarm from a tire pressure alarm by a warning indicator, and the transmitter has a predetermined sampling cycle. The tire pressure of the wheel to which the transmitter is attached is acquired every time, and the tire pressure decreases and the alarm condition is determined by the alarm condition determination means for determining whether the acquired tire pressure decreases and the alarm condition is satisfied. If it is determined that the condition is satisfied, the apparatus has an abnormality information transmitting means for transmitting abnormality information to the receiving means.

In this way, the tire pressure is monitored by each transmitter, and when the tire pressure decreases, abnormality information is transmitted to the receiving means on the vehicle body side. Therefore, it is possible to monitor the tire air pressure at a shorter cycle compared to the conventional case. When the tire air pressure decreases, it is immediately notified to the receiving means whether it is suddenly decompressed or slowly decompressed, and is communicated to the driver via the alarm indicator. be able to. Therefore, even when the tire pressure is gradually reduced, it is possible to issue a warning in a shorter time from the occurrence of an abnormality.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawing
FIG. 1 is a diagram illustrating an overall configuration of a tire pressure detection device according to a first embodiment of the present disclosure. FIG. 2A is a block diagram illustrating a schematic configuration of a transmitter attached to each wheel, and FIG. 2B is a block diagram illustrating a schematic configuration of an RF receiver, a control device, and an antenna driver provided in the vehicle body. is there. FIGS. 3A and 3B are flowcharts showing processing performed by the microcomputer of the control device provided in the vehicle body. FIGS. 4A and 4B are flowcharts showing processing performed by the microcomputer of the transmitter provided in each wheel. FIG. 5A is a timing chart showing abnormality determination of tire air pressure as a comparative example, and FIG. 5B is a timing chart showing abnormality determination of the present embodiment. FIG. 6 is a flowchart illustrating details of threshold value checking processing executed by each transmitter of the tire pressure detection device according to the second embodiment of the present disclosure. FIG. 7 is a flowchart illustrating details of threshold value checking processing executed by each transmitter of the tire pressure detection device according to the third embodiment of the present disclosure. FIG. 8 is a flowchart illustrating details of threshold value checking processing executed by each transmitter of the tire pressure detection device according to the fourth embodiment of the present disclosure. FIG. 9 is a flowchart illustrating details of threshold value checking processing executed by each transmitter of the tire pressure detection device according to the fifth embodiment of the present disclosure. FIG. 10 is a timing chart showing the operation when the threshold value is confirmed. FIG. 11 is a timing chart showing an operation at the time of threshold value confirmation of the tire pressure detecting device according to another embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a diagram illustrating an overall configuration of a tire air pressure detection device according to a first embodiment of the present disclosure. The up-down direction of the paper surface in FIG. With reference to this figure, the tire pressure detecting device in the present embodiment will be described.

As shown in FIG. 1, the tire air pressure detecting device is attached to the vehicle 1, and includes a transmitter 2 (2a to 2d), an RF receiver 3, a control device 4, an antenna driver 5, an antenna 51, and an alarm display 6. It is configured with.

As shown in FIG. 1, the transmitters 2a to 2d are attached to the wheels 7a to 7d in the vehicle 1. The transmitters 2a to 2d detect the air pressure of the tires attached to the wheels 7a to 7d every predetermined sampling period, and also transmit data on the tire air pressure indicating the detection result at the predetermined periodic transmission period and abnormality in the frame. And RF transmission. Further, the RF receiver 3 and the control device 4 are attached to the vehicle body 8 side of the vehicle 1 and receive the RF frames transmitted from the transmitters 2a to 2d, and based on the detection signals stored therein. The tire air pressure is detected by performing various processes and calculations. These RF receiver 3 and control device 4 correspond to receiving means. FIG. 2A shows a schematic configuration of the transmitter 2 (2a to 2d) attached to the wheels 7a to 7d, and FIG. 2B shows the RF receiver 3 and the control device 4 provided on the vehicle body 8 side. 2 shows a schematic configuration of the antenna driver 5.

As shown in FIG. 2A, the transmitter 2 (2a to 2d) includes a sensing unit 21, a microcomputer 22, an antenna 23, and a battery 24, and is based on power supply from the battery 24. Each part is driven.

The sensing unit 21 includes a diaphragm type pressure sensor 21a and a temperature sensor 21b, for example, and outputs a detection signal corresponding to the tire pressure and a detection signal corresponding to the temperature.

The microcomputer 22 is a general one having a CPU, ROM, RAM, I / O, and the like, and is a well-known one having a control unit (first control unit), a transmission unit, and the like. A predetermined process is executed in accordance with the stored program. In the memory in the control unit, individual ID information including identification information unique to the transmitter for identifying each of the transmitters 2a to 2d and identification information unique to the vehicle for identifying the host vehicle is stored.

The microcomputer 22 receives alarm threshold information including an alarm threshold and an alarm change threshold through the antenna 23, and stores the alarm threshold information. Further, the microcomputer 22 receives a detection signal relating to the tire air pressure from the sensing unit 21 every predetermined sampling period, and detects the tire air pressure of the wheels 7a to 7d to which the transmitter 2 is attached by processing the signal. . A decrease in tire air pressure is detected based on the tire air pressure detected at each sampling period and alarm threshold information. Specifically, the tire air pressure is compared with an alarm threshold, and when the tire air pressure falls below the alarm threshold, it is determined that the tire air pressure decreases, or the tire air pressure change gradient is compared with the alarm change threshold. If it becomes above, it will determine with the rapid pressure reduction of a tire pressure. When a decrease in tire air pressure or sudden pressure reduction is detected, abnormal information indicating that the tire air pressure is abnormal is stored in the frame together with ID information of each transmitter 2a to 2d, and this is received by RF radio waves. Transmit to the machine 3 side. Further, the microcomputer 22 performs periodic transmission for transmitting data related to the tire pressure detected at each sampling cycle to the RF receiver 3 at a predetermined transmission cycle at normal times when no abnormality in the tire pressure is detected. . The transmission cycle of this regular transmission is set longer than the sampling cycle, and the tire pressure data transmitted is, for example, the tire pressure detected at the sampling cycle closest to the transmission cycle.

The transmitters 2a to 2d configured as described above are attached to, for example, air injection valves in the wheels of the wheels 7a to 7d, and are arranged so that the sensing unit 21 is exposed inside the tire. As a result, the corresponding tire pressure is detected, and as described above, the frame is transmitted at the predetermined transmission timing through the antenna 23 provided in each of the transmitters 2a to 2d, so that the RF receiver 3 side can be transmitted. Data related to tire pressure is transmitted.

Further, as shown in FIG. 2 (b), the RF receiver 3 is configured to include a receiving antenna 31 and a receiving circuit 32. The receiving antenna 31 is for receiving frames sent from the transmitters 2a to 2d. The receiving antenna 31 is fixed to the vehicle body 8 and receives frames transmitted from the transmitters 2a to 2d of the wheels 7a to 7d. The receiving antenna 31 is disposed, for example, on the pillar and ceiling (in the roof) of the vehicle 1. The reception circuit 32 functions as an input unit that receives transmission frames from the transmitters 2 a to 2 d received by the reception antenna 31 and sends the frames to the control device 4.

The control device 4 corresponds to a second control unit, and is constituted by a known microcomputer 41 having a CPU, ROM, RAM, I / O and the like, and performs tire air pressure detection processing according to a program stored in the ROM or the like. Do. Specifically, the control device 4 detects the tire air pressure of the wheels 7a to 7d based on the ID information of the transmitters 2a to 2d stored in the frame and the data related to the tire air pressure. If the received frame includes abnormality information indicating that the tire air pressure is abnormal, the alarm information is transmitted to the alarm indicator 6. The control device 4 and the alarm indicator 6 may be directly connected by wiring or may be connected through a communication line such as an in-vehicle LAN.

Further, the control device 4 stores alarm threshold information used to determine a decrease in tire air pressure in each of the transmitters 2a to 2d in a memory (storage element) such as a ROM, RAM, or EEPROM provided in the CPU. It is. The control device 4 also performs an operation of reading out the alarm threshold information and transmitting it to the transmitters 2a to 2d through the antenna driver 5. As the alarm threshold value information, the alarm threshold value to be compared with the tire pressure as described above and the alarm change threshold value to be compared with the change gradient of the tire pressure are stored in the memory.

In the present embodiment, the control device 4 detects a decrease in tire air pressure mainly based on abnormality information stored in transmission frames from the transmitters 2a to 2d. However, a decrease in tire air pressure may also be detected by the control device 4 on the basis of data relating to tire air pressure stored in a transmission frame that has been transmitted regularly.

The antenna driver 5 includes an antenna 51 (51a to 51d) and a driver circuit 52. The antennas 51a to 51d are installed in the vicinity of the wheels 7a to 7d, and transmit alarm threshold information to the transmitters 2a to 2d as, for example, LF radio waves. The driver circuit 52 functions as an output unit that transmits LF radio waves indicating alarm threshold information from the antennas 51a to 51d to the transmitters 2a to 2d.

The alarm indicator 6 functions as an alarm unit. As shown in FIG. 1, the alarm indicator 6 is arranged in a place where the driver can visually recognize, for example, an alarm lamp installed in an instrument panel in the vehicle 1, a navigation system And a multi-display in a meter. For example, when a signal indicating that the tire air pressure has decreased is sent from the control device 4, the alarm display device 6 displays a message to that effect to warn the driver that the tire air pressure has decreased.

Next, tire pressure detection processing by the tire pressure detection device configured as described above will be described. FIGS. 3A and 3B are flowcharts showing processing performed by the microcomputer 41 of the control device 4 provided on the vehicle body 8 side. 4 (a) and 4 (b) are flowcharts showing processing performed by the microcomputer 22 of the transmitters 2a to 2d provided in the wheels 7a to 7d. Hereinafter, processing executed by the control device 4 and the transmitters 2a to 2d will be described with reference to these drawings.

First, when an ignition switch (not shown) is turned on, the control device 4 executes alarm threshold information transmission processing shown in FIG. In step 100, the alarm threshold information stored in the memory of the microcomputer 41 is read. The alarm threshold information includes information related to an alarm threshold that is compared with the absolute value of the detected tire air pressure, and an alarm change threshold that is compared with a change per unit time of the tire air pressure. As for the alarm threshold and the alarm change threshold, a value set directly as a numerical value may be used, or a value calculated from a recommended pressure may be used. Here, the alarm threshold value and the alarm change threshold value are exemplified as the alarm threshold information, but only one of them, for example, only the alarm threshold value may be used.

Next, in step 110, the alarm threshold information read out in step 100 is output. That is, a frame in which a threshold setting command is stored together with alarm threshold information is transmitted to the antenna driver 5, and each of the transmitters 2a to 2d transmits the frame from each of the antennas 51a to 51d. Thus, when the frames are received by the transmitters 2a to 2d, the microcomputer 22 of the transmitters 2a to 2d receives alarm threshold value or alarm change threshold data included in the alarm threshold information based on the instruction of the threshold setting command. Is read out and stored, and a signal indicating completion of threshold data setting is output. For this reason, in step 120, a signal indicating completion of the threshold data setting is received, and when it is received, it is confirmed that the transmitter 2a to 2d is normally set, and the alarm threshold information transmission processing is completed. Here, when a signal indicating completion of threshold data setting is not received, the processing of

steps

100 and 110 is repeated again and retries are performed, so that the alarm threshold and the alarm change threshold are surely set in each of the transmitters 2a to 2d. Can be set.

Here, the signal indicating the completion of the threshold data setting is received in step 120, but this processing is performed in order to more reliably set the alarm threshold value and the alarm change threshold value in each of the transmitters 2a to 2d. It can be done as needed. In addition, when the processing of

steps

100 and 110 is repeated by retrying, if there is no valid reply even after a certain number of retries, it is considered that the radio wave is difficult to reach or the transmitters 2a to 2d are defective. It is preferable to provide a timeout. When performing the retry, the retry may be performed only for the transmitters 2a to 2d that have not received the signal indicating the completion of the threshold data setting.

Further, the abnormality information reception process shown in FIG. 3B is performed as a flow different from the alarm threshold information transmission process shown in FIG. This process may be performed after the alarm threshold information transmission process in FIG. 3A is completed, but may be performed independently of the alarm threshold information transmission process.

First, in step 200, it is determined whether or not abnormality information has been received. As will be described later, the abnormality information is the tire pressure when the tire pressure detected by the transmitters 2a to 2d is less than or equal to the alarm threshold, or when the change gradient of the tire pressure is greater than or equal to the alarm change threshold. This information is transmitted when an abnormality occurs. In this step, it is determined whether or not this abnormality information has been received. Here, it waits until it receives abnormality information, and when abnormality information is received, it progresses to step 210 and transmits alarm information to the alarm indicator 6. Thereby, the warning indicator 6 warns the driver of a decrease in tire air pressure by displaying that the tire air pressure has decreased based on the received alarm information.

On the other hand, in each of the transmitters 2a to 2d, the microcomputer 22 performs the alarm threshold value setting process shown in FIG. 4 (a) for each predetermined control period based on the power supply from the battery 24, and for each predetermined sampling period. The tire pressure monitoring process shown in FIG.

In the alarm threshold setting process shown in FIG. 4A, first, in step 300, it is determined whether or not a threshold setting command has been received. As described above, when the frame storing the threshold setting command together with the alarm threshold information is transmitted at step 110 in FIG. 3A on the control device 4 side, the frame is received by each of the receivers 2a to 2d. . When the microcomputer 22 of each of the receivers 2a to 2d receives the frame in which the threshold setting command is stored, it determines that the threshold setting command has been received in this step.

Here, it waits until the threshold setting command is received. If it is determined that the threshold setting command has been received, the process proceeds to step 310 to read the alarm threshold information stored in the received frame. In step 320, the alarm threshold value information is stored in a memory such as a ROM, RAM, or EEPROM provided in the CPU, a signal indicating completion of threshold data setting is transmitted, and the process ends. At this time, when alarm threshold value information is stored in a storage element such as an EEPROM as storage in a memory or the like, it is preferable to store it in a different memory area every time in consideration of the rewrite life.

Further, in the tire pressure monitoring process shown in FIG. 4B, the tire pressure is monitored based on the alarm threshold information stored in the alarm threshold setting process, and a decrease in the tire pressure is detected. First, in step 400, it is determined whether an alarm condition is satisfied. Specifically, the pressure and temperature are detected by the pressure sensor 21a and the temperature sensor 21b provided in the sensing unit 21 for each predetermined sampling period, and each of the transmitters 2a to 2d is based on the detection result. The tire pressure of the wheels 7a to 7d to which is attached is calculated. When the tire pressure falls below the warning threshold, or when the tire pressure change gradient, for example, the difference between the tire pressures of the current sampling period and the previous sampling period becomes equal to or higher than the warning change threshold, It is said that

Here, the system waits until the alarm condition is satisfied, and when the alarm condition is satisfied, the process proceeds to step 410 to transmit abnormal information indicating that the tire air pressure has decreased by RF radio waves. When this abnormality information is received by the receiver 3, it is transmitted to the control device 4, so that it is determined at step 200 in FIG. Will be displayed.

Thus, the transmitters 2a to 2d themselves detect that the tire air pressure of the wheels 7a to 7d to which they are attached has decreased, and when the tire air pressure has decreased, this is indicated. Is transmitted to the control device 4 on the vehicle body 8 side. For this reason, not only in the case of sudden depressurization but also in the case of slow depressurization, when the tire air pressure decreases, it can be immediately transmitted to the control device 4.

In FIG. 4B, the periodic transmission flow is not shown, but periodic transmission is also performed. The periodic transmission cycle is set to be equal to or more than a plurality of sampling cycles. Information on the tire air pressure calculated every predetermined sampling period is transmitted from each of the transmitters 2a to 2d for each periodical transmission period. At this time, as described above, each transmitter 2a to 2d can detect a decrease in tire air pressure by itself, so that compared with a case where a decrease in tire air pressure is determined by a receiver on the vehicle body as in the past, The period of periodic transmission can be increased. In other words, when determining the decrease in tire pressure with the receiver on the vehicle body as in the past, if the tire pressure is suddenly reduced unless the periodic transmission cycle is shortened and the tire pressure is monitored every short time I can't deal with it. On the other hand, as in this embodiment, it is possible to detect a decrease in tire air pressure on the transmitters 2a to 2d side, and by shortening the sampling cycle, the tire air pressure immediately decreases even when the tire air pressure is suddenly reduced. It is possible to transmit the abnormal information indicating that it has been performed, and it is possible to reduce power consumption because data transmission is basically performed only by sampling. For this reason, even when the tire pressure is slowly reduced, an alarm can be issued in a shorter time from the occurrence of an abnormality, and a reduction in battery life can be suppressed.

FIG. 5 (a) is a timing chart showing an abnormality determination when the tire pressure is slowly reduced as a comparative example, and FIG. 5 (b) is a timing chart showing the abnormality determination of the present embodiment. In the comparative example shown in FIG. 5 (a), the abnormality determination is performed by the vehicle-side control device, and information on the tire pressure can be transmitted to the vehicle-side receiver only for each periodic transmission cycle. Even if a pressure abnormality occurs in the middle of a periodic transmission cycle, the abnormality is not transmitted until the next periodic transmission cycle comes. On the other hand, when the tire pressure is monitored by each transmitter 2a to 2d and is transmitted to the control device 4 when an abnormality occurs as in this embodiment, the sampling cycle can be shortened, and a pressure abnormality occurs. Sometimes it can be immediately communicated to the control device 4.

As described above, in the tire pressure detecting device of the present embodiment, the tire pressure is monitored by each of the transmitters 2a to 2d, and abnormality information is transmitted to the control device 4 on the vehicle body 8 side when the tire pressure decreases. ing. Since each of the transmitters 2a to 2d monitors the tire pressure at a sampling cycle shorter than the regular transmission cycle, the tire pressure can be monitored at a cycle shorter than that of the comparative example. Further, since the tire pressure is monitored at a short sampling period, when the tire pressure decreases, it is possible to promptly notify the controller 4 whether the pressure is reduced or suddenly, and to the driver via the alarm display device 6. Therefore, even when the tire pressure is gradually reduced, it is possible to issue a warning in a shorter time from the occurrence of an abnormality.

Further, since the tire pressure can be monitored by the transmitters 2a to 2d, it is not necessary to monitor the tire pressure finely by the control device 4 on the vehicle body 8 side. For this reason, the period of periodic transmission can be lengthened, power consumption for periodic transmission can be reduced, and a decrease in battery life can also be suppressed.

(Second Embodiment)
A second embodiment of the present disclosure will be described. The tire air pressure detection device according to the present embodiment is configured to be able to make a request for confirmation of alarm threshold information to the transmitters 2a to 2d with respect to the first embodiment, and is otherwise the same as the first embodiment. Therefore, the difference from the first embodiment will be mainly described.

In the first embodiment, it is shown that the alarm threshold value and the alarm change threshold data included in the alarm threshold information are stored by outputting a signal indicating the completion of the threshold data setting, but in the present embodiment, the stored data It is possible to determine whether or not is correct regular data.

Specifically, the control device 4 outputs a threshold value confirmation request to the antenna driver 5 when it is desired to determine whether or not the data stored in each of the transmitters 2a to 2d is correct regular data. For example, a threshold value confirmation request is issued when an ignition switch (not shown) is turned on, or when a predetermined period has elapsed since the previous threshold value confirmation request was issued. Based on this, the driver circuit 52 of the antenna driver 5 causes the antennas 51a to 51d to output LF radio waves including a threshold value confirmation request and threshold value confirmation data, and causes each of the transmitters 2a to 2d to receive it. Then, each of the transmitters 2a to 2d receives the LF radio wave including the threshold value confirmation request, and executes the flowchart shown in FIG.

That is, each of the transmitters 2a to 2d executes the threshold value confirmation process shown in FIG. 6 for each predetermined control cycle. Then, in the request trigger reception determination shown in step 500, the process waits until receiving the LF radio wave corresponding to the request trigger. If it is determined in step 500 that the reception is received, the reception intensity of the LF radio wave (request trigger) is determined. , And the processing after step 510 is executed.

In step 510, stored alarm threshold value information reading processing is performed. In this process, data relating to an alarm threshold value stored in a memory (storage element) such as a ROM, a RAM, or an EEPROM provided in the CPU of the microcomputer 22 is read out. The data relating to the alarm threshold means the current alarm threshold information sent from the vehicle body side through the antenna driver 5 and stored therein, but alarm threshold information stored in advance as mirror data (hereinafter simply referred to as mirror data). If there is, the mirror data is also included.

Subsequently, the process proceeds to step 520, and it is determined whether or not the data regarding the alarm threshold value read in step 510 is regular data. For example, the threshold value confirmation data included in the received LF radio wave is collated with the alarm threshold value information read in step 510, and it is determined whether or not they match. Also, the alarm threshold information read in step 510 may be collated with the mirror data to determine whether or not they match.

In step 520, when the alarm threshold information stored in each transmitter 2 is lost, it is determined that the data is not regular data.

If an affirmative determination is made in step 520, the routine proceeds to step 530, where normal transmission data is set (stored) in the same frame as the data related to tire pressure or in another frame. Similarly, if a negative determination is made in step 520, the process proceeds to step 540, and the abnormal time transmission data is set (stored) in the same frame as the data related to the tire pressure or in another frame. For example, normal transmission data or abnormal transmission data is set using one bit or several bits allocated to indicate whether the transmission frame is normal or abnormal.

Then, the process proceeds to step 550, and in order to avoid interference due to the coincidence of the transmission timings of the transmitters 2a to 2d, normal transmission data or abnormal transmission data is provided with a delay according to the reception intensity of the LF radio wave. RF transmission is performed for the frame in which is set. Thereby, the RF receiver 3 receives a frame in which normal transmission data or abnormal transmission data is set, and the alarm threshold information stored in each of the transmitters 2a to 2d is regular data in the control device 4. It is possible to determine whether or not.

Thus, it is possible to determine whether or not the alarm threshold information stored in each transmitter 2 is regular data. If the regular data is not stored, the control device 4 executes a process of storing alarm threshold information again for at least the transmitters 2a to 2d for which the regular data is not stored (FIG. 4 ( a)). As a result, it is possible to reset the alarm threshold information at the time of abnormality, and it is possible to correctly detect a decrease in tire air pressure based on the regular data. In the case of an abnormality, the state can also be transmitted to the driver through the alarm indicator 6 or the like.

In the above, the threshold confirmation data in the LF radio wave is collated with the alarm threshold information read in step 510. Instead of this, or in addition to this, legitimate data is obtained by extracting and collating an error correction code (ECC) or frame check code (FCC) character from the read alarm threshold information and performing a parity check. It may be determined whether or not. If mirror data is included, the current alarm threshold information may be self-repaired using the mirror data. In that case, when the transmission data at the time of abnormality is set, data indicating that self-repair is performed can be set at the same time.

Further, after RF transmission is performed on the frame in which the abnormal transmission data is set in step 550, alarm threshold information for resetting may not be sent to the transmitters 2a to 2d that transmitted the frame. . In that case, the RF transmission of the frame in which the abnormal-time transmission data is set may be repeated until alarm threshold information for resetting is sent.

In addition, when there is a margin in the number of bits of the frame for RF transmission, the currently set alarm threshold information may be set in the frame in addition to normal transmission data or abnormal transmission data. In that case, it is possible to determine whether the currently set alarm threshold information is normal or abnormal on the control device 4 side. For example, ECC and FCC characters are extracted from the alarm threshold information and collated, parity check is performed to determine whether the data is legitimate data, mirror data is provided, collated with mirror data, and collated It can be determined whether or not the data.

(Third embodiment)
A third embodiment of the present disclosure will be described. In this embodiment, the transmitters 2a to 2d are made to check alarm threshold value information, and the others are the same as those in the first embodiment, so only the parts different from the first embodiment will be described. To do.

In this embodiment, alarm threshold information similar to that in the second embodiment is checked at the timing of periodic transmission of data related to tire pressure. Other than this timing, it is the same as in the second embodiment.

Each of the transmitters 2a to 2d executes the flowchart shown in FIG. 7 for each predetermined control cycle, and in the air pressure transmission timing determination shown in step 600, it is determined that it is the timing of periodic transmission of data related to tire air pressure. Then, the processing after step 610 is executed.

Specifically, in steps 610 to 640, processing similar to that in steps 510 to 540 of FIG. 6 described in the second embodiment is executed. However, in step 620, since threshold confirmation data has not been received, for example, the alarm threshold information read in step 610 is compared with mirror data to determine whether or not they match. Also, the frame for setting normal transmission data or abnormal transmission data may be a separate frame from the frame for storing data related to tire air pressure. A frame is preferable. In this way, frame transmissions performed thereafter can be combined into one, and the battery life can be improved along with the reduction in power consumption.

Thereafter, the process proceeds to step 650, and a frame in which normal transmission data or abnormal transmission data is set is RF-transmitted. Thereby, the RF receiver 3 receives a frame in which normal transmission data or abnormal transmission data is set, and the alarm threshold information stored in each of the transmitters 2a to 2d is regular data in the control device 4. It becomes possible to determine whether or not.

As described above, the alarm threshold information may be confirmed by each of the transmitters 2a to 2d at the timing of periodic transmission of data related to tire pressure. Thereby, the effect similar to 2nd Embodiment can be acquired. And by sending the determination result of whether or not the alarm threshold information is regular data together with the periodic transmission, it is not necessary to perform RF transmission only for sending the determination result, so that the power consumption can be reduced and the electrical life can be improved. Can be planned.

(Fourth embodiment)
A fourth embodiment of the present disclosure will be described. In this embodiment, the transmitters 2a to 2d are configured to check alarm threshold value information. The other aspects are the same as those in the first embodiment, and therefore only the parts different from the first embodiment will be described. To do.

In this embodiment, alarm threshold information similar to that in the third embodiment is checked every predetermined control period regardless of the timing of periodic transmission of data related to tire pressure. Other than this timing, the second embodiment is almost the same as the second embodiment, and only the parts different from the third embodiment will be described.

The transmitters 2a to 2d execute the flowchart shown in FIG. 8 for each predetermined control cycle, and execute the processes of steps 700 to 730 for each predetermined control cycle. In steps 700 and 710, processing similar to that in steps 610 and 620 of FIG. 6 described in the third embodiment is executed. When a negative determination is made at step 710, the process proceeds to step 720 and the same process as at step 640 is executed. When an affirmative determination is made, the process is terminated as it is. If the current alarm threshold information is regular data, you may send a frame with the normal transmission data set, but if it is normal, you do not need to respond to anything. Also good. In this way, battery life can be improved by reducing power consumption.

In step 720, the transmission data at the time of abnormality is set (stored) in the same frame as the data related to the tire pressure or in another frame. Then, the process proceeds to step 730, where the frame in which the abnormal time transmission data is set is RF-transmitted and a threshold data retransmission request is transmitted. For the threshold data retransmission request at this time, if the command is stored in the frame in which the abnormal transmission data is set, both the abnormal transmission data and the threshold data retransmission request data are transmitted in one frame transmission. Can be done.

As described above, the same effect as that of the third embodiment can be obtained even if the transmitters 2a to 2d are checked for the alarm threshold information every predetermined control period. In the present embodiment, the frame in which the abnormal transmission data is set is RF-transmitted and a threshold data retransmission request is transmitted. However, as in the second and third embodiments, it is recognized that the regular data is not stored based on the abnormal transmission data, and at least the regular data is not stored in the transmitters 2a to 2d from the control device 4. A process for storing the alarm threshold information again may be executed on the object. Of course, for the second and third embodiments, as in the present embodiment, a threshold data retransmission request may be issued when no regular data is stored from the transmitters 2a to 2d.

(Fifth embodiment)
A fifth embodiment of the present disclosure will be described. In the present embodiment, the determination as to whether or not the alarm threshold information is regular data is not performed by the transmitters 2a to 2d, but the current alarm threshold information stored from the transmitters 2a to 2d is used as the control device 4 side. So that the control device 4 can make a determination.

In the present embodiment, the control device 4 is caused to execute a threshold value confirmation request process when it is time to confirm the alarm threshold value information for determining whether or not the alarm threshold value information is regular data. For example, the threshold value confirmation request process is executed at a predetermined cycle or at a timing such as after a predetermined time has elapsed since the alarm threshold value information was transmitted to each of the transmitters 2a to 2d. Specifically, in order to cause each transmitter 2a to 2d to check alarm threshold information at that timing, LF radio waves indicating read commands are output from the antennas 51a to 51d through the driver circuit 52 of the antenna driver 5. To do.

Each of the transmitters 2a to 2d executes the flowchart shown in FIG. 9 for each predetermined control cycle. When it is determined in the read command reception determination shown in step 800 that the read command is received, step 810 is performed. The subsequent processing is executed.

In step 810, each of the transmitters 2a to 2d performs a stored alarm threshold value information reading process, similarly to step 510 of FIG. 6 described in the second embodiment. Further, the alarm threshold information is encoded (for example, data length reduction or redundancy is added) as necessary, or ECC or FCC character or parity check data is extracted from the read alarm threshold information. Of course, the raw value of the alarm threshold information may be used as it is without encoding. That is, any data regarding alarm threshold information may be used regardless of the alarm threshold information of the raw value and the alarm threshold information that has been encoded.

Then, the process proceeds to step 820, and a transmission frame is created by arranging the generated data obtained by performing the raw value or encoding of the alarm threshold information on the RF transmission data together with the ID information unique to the transmitter.

Thereafter, the process proceeds to step 830 to perform data transmission at the RF transmission timing. For example, in order to avoid interference due to coincidence of transmission timings of the transmitters 2a to 2d, a frame in which RF transmission data is set is RF-transmitted with a delay corresponding to the reception intensity of the LF radio wave.

For example, as shown in FIG. 1, when the number of antennas 51 corresponding to each of the wheels 7a to 7d is provided, the operation shown in the timing chart of FIG. 10 is performed. That is, when an LF radio wave indicating a threshold value confirmation request is output in turn from each antenna 51a to 51d, an alarm is given each time from the transmitter 2a to 2d attached to the wheels 7a to 7d corresponding to each antenna 51a to 51d. Threshold information is returned. At this time, a threshold value confirmation request is issued in order from each antenna 51a to 51d, and when the threshold value confirmation request LF radio wave is received, alarm threshold value information is returned from each transmitter 2a to 2d. The alarm threshold information is returned at a different timing from 2d. Therefore, interference due to the coincidence of transmission timings of the transmitters 2a to 2d does not occur.

It should be noted that when the alarm threshold information is replied, it is only necessary to transmit the LF radio wave from the next antenna 51, but there may be no effective reply. In that case, it is possible to retry by transmitting the LF radio wave again. Even in such a case, if a valid reply is not received after a certain number of retries, it is considered that the radio wave is difficult to reach or the transmitters 2a to 2d are defective. Therefore, it is preferable to provide a timeout.

When a frame in which alarm threshold information subjected to raw values or encoding is stored in this way is transmitted, it is received by the RF receiver 3. Then, by being sent to the control device 4, it is possible to determine whether or not the alarm threshold information stored in each of the transmitters 2a to 2d is regular data. In this way, it is possible to transmit alarm threshold information from each transmitter 2 and determine whether or not the alarm threshold information is regular data on the control device 4 side.

(Other embodiments)
(1) In the above embodiment, four antennas 51a to 51d are provided corresponding to the wheels 7a to 7d, and alarms are individually given to the transmitters 2a to 2d attached to the wheels 7a to 7d from the antennas 51a to 51d. A frame storing threshold information is transmitted. However, this is merely an example. For example, there are two antennas corresponding to the

transmitters

2a and 2b of both front wheels 7a and 7b and the antennas corresponding to the

transmitters

2c and 2d of both

rear wheels

7c and 7d. It is also possible to provide a single antenna that can transmit frames to all the transmitters 2a to 2d of all the wheels 7a to 7d.

When two antennas are used, for example, one antenna is arranged near the front of the vehicle while being arranged at different distances from the front wheels 7a and 7b, and the other antenna 51 is arranged near the vehicle rear and from both the

rear wheels

7c and 7d. It is set to be arranged at different distances. In this case, one antenna 51 outputs LF radio waves to the

transmitters

2a and 2b of both front wheels 7a and 7b, and the other antenna 51 outputs to the

transmitters

2c and 2d of both

rear wheels

7c and 7d. What is necessary is just to output LF radio waves.

Even in such a form, the same operation as in each of the above embodiments can be performed. For example, when a threshold value confirmation request is made as in the fifth embodiment, an operation like the timing chart shown in FIG. 11 is performed.

That is, when the LF radio wave indicating a threshold confirmation request is output to the

transmitters

2a and 2b of both front wheels 7a and 7b, the distance from the antenna 51 to both front wheels 7a and 7b is different. The reception intensity of the LF radio wave becomes a different value. For this reason, the alarm threshold information can be returned from the

transmitters

2a and 2b at different timings in order by performing RF transmission with a delay corresponding to the reception intensity. Similarly, when the LF radio wave indicating the threshold value confirmation request is output to the

transmitters

2c and 2d of the

rear wheels

7c and 7d, the distance from the antenna 51 to the

rear wheels

7c and 7d is different. The reception strengths of the LF radio waves at 2c and 2d are different values. For this reason, alarm threshold information can be returned at different timings in order from the

transmitters

2c and 2d by performing RF transmission with a delay corresponding to the reception intensity. Therefore, interference due to the coincidence of transmission timings of the transmitters 2a to 2d does not occur.

Even when two antennas 51 are used, it is only necessary to transmit the LF radio wave from the next antenna 51 when the alarm threshold information is replied, but there may be no effective reply. In that case, it is possible to retry by transmitting the LF radio wave again. Even in such a case, if a valid reply is not received after a certain number of retries, it is considered that the radio wave is difficult to reach or the transmitters 2a to 2d are defective. Therefore, it is preferable to provide a timeout.

(2) Further, the alarm threshold information such as the alarm threshold value and the alarm change threshold value of each wheel 7a to 7d may be the same for both front wheels 7a, 7b and both

rear wheels

7c, 7d, or different. Also good.

When the alarm threshold information of the wheels 7a to 7d is the same, and there are four antennas 51, the alarm threshold information can be transmitted to the wheels 7a to 7d simultaneously or at different timings. When there are two antennas 51, the alarm threshold information may be transmitted to the front wheels 7a, 7b and the

rear wheels

7c, 7d in order, or the alarm threshold information may be transmitted simultaneously. Also in this case, when the alarm threshold information is normally stored in each of the transmitters 2a to 2d, a signal indicating the completion of threshold data setting is returned, but if there is no response, a fixed number of retries are performed. preferable. When performing the retry, the retry may be performed only for the transmitters 2a to 2d that have not received the signal indicating the completion of the threshold data setting.

The same applies to the case where the front wheels 7a and 7b are different from the

rear wheels

7c and 7d. That is, when there are four antennas 51, the alarm threshold information can be transmitted to the wheels 7a to 7d simultaneously or at different timings. When there are two antennas 51, the alarm threshold information may be transmitted to the front wheels 7a, 7b and the

rear wheels

7c, 7d in order, or the alarm threshold information may be transmitted simultaneously. However, in these cases, the alarm threshold information for the front wheels is transmitted from the antenna 51 corresponding to both front wheels 7a and 7b, and the alarm threshold information for the rear wheels is transmitted from the antenna 51 corresponding to both

rear wheels

7c and 7d. At this time, the wheel position detection has been completed in the case of the tire pressure detecting device having the wheel position detecting function for identifying which of the wheels 7a to 7d each transmitter 2a to 2d is attached to. If so, the ID information of the target transmitter may be added to the alarm threshold information. In this way, even if both the LF radio waves transmitted from the two antennas 51 are received by the transmitters 2a to 2d, the target LF radio wave can be specified. On the contrary, if the wheel position detection is not completed, an operation for executing the wheel position detection and completing it is performed before the alarm threshold information is transmitted to the transmitters 2a to 2d. The alarm threshold information may be transmitted to the transmitters 2a to 2d after waiting for the result.

When there are four or two antennas 51 for transmitting alarm threshold information, as described above, the

transmitters

2a and 2b for both front wheels 7a and 7b and the

transmitters

2c and 2d for both

rear wheels

7c and 7d are used. Different alarm threshold information may be transmitted. However, when there is one antenna 51, this is performed as follows.

That is, each transmitter 2a to 2d is made to measure the reception intensity, and when the antenna 51 transmits the alarm threshold information of both front wheels 7a and 7b and the alarm threshold information of both

rear wheels

7c and 7d, different signal strengths are transmitted. Try to transmit by radio wave. In each of the transmitters 2a to 2d, a minimum reception intensity that permits reception of alarm threshold information is set. The antenna 51 is disposed so as to be close to either the front wheels 7a, 7b or the

rear wheels

7c, 7d. In this way, the transmitter 2 closer to the antenna 51 out of the front wheels 7a and 7b and the

rear wheels

7c and 7d receives the different alarm threshold information, and the side with the stronger reception intensity has its own alarm threshold. It can be determined that it is information. Further, in the transmitter 2 far from the antenna 51 out of both the front wheels 7a and 7b and the both

rear wheels

7c and 7d, the alarm threshold information included in the radio wave exceeding the minimum reception intensity is determined as the own alarm threshold information. can do.

(3) In the above embodiment, LF radio waves are used for transmission of alarm threshold information, and RF radio waves are used for transmission of abnormal information indicating a decrease in tire air pressure. It can be arbitrarily selected.

(4) In the above embodiment, the case where only one RF receiver 3 is provided has been described. However, a plurality of transmitters 2a to 2d may be provided. Also in this case, the number corresponding to all the transmitters 2a to 2d of all the wheels 7a to 7d may be provided, or the number corresponding to the

transmitters

2a and 2b of both front wheels 7a and 7b and the rear wheels 7c, Two of the transmitters corresponding to the

transmitters

2c and 2d of 7d may be used. Further, only a plurality of antennas 31 in the RF receiver 3 may be provided.

(5) In the above embodiment, the condition for reducing the tire air pressure is shown as the alarm condition. However, the alarm condition can be set not only for the tire air pressure decrease but also for the tire air pressure increase and the temperature increase. For example, an alarm may be issued when the tire air pressure increases above a specified value, or when the temperature inside the tire is above a specified value.

Also, the alarm conditions can be set to different conditions independently for each of the wheels 7a to 7d. Of course, it is possible to set different conditions for the front and rear wheels. In that case, in order to avoid radio waves transmitted to the transmitters 2a to 2d from interfering with each other, each transmitter 2a to 2d is attached with alarm ID information unique to each transmitter 2a to 2d. It may be possible to determine whether or not has received its own alarm threshold information.

(6) Note that the steps shown in each figure correspond to means for executing various processes. Specifically, the part that executes the process shown in step 400 corresponds to an alarm condition determining unit, and the part that executes the process shown in step 210 corresponds to an abnormality information transmitting unit.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

Each of the plurality of wheels (7a to 7d) equipped with tires is attached to each of the wheels (7a to 7d), and has a sensing unit (21) for acquiring tire air pressure at the attached wheels (7a to 7d). A transmitter (2) for transmitting abnormal information indicating that the tire pressure is reduced;
Receiving means (3, 4) provided on the vehicle body (8) side and outputting alarm information instructing an alarm of a decrease in tire air pressure when receiving the abnormality information;
In a tire pressure detecting device comprising: an alarm indicator (6) that gives a warning of a decrease in tire air pressure based on the alarm information from the receiving means (3, 4),
The transmitter (2) acquires the tire air pressure of the wheels (7a to 7d) to which the transmitter (2) is attached at every predetermined sampling period, and the acquired tire air pressure decreases to satisfy the alarm condition. If it is determined by the alarm condition determination means (400) that determines whether or not the tire pressure is reduced and the alarm condition is satisfied by the alarm condition determination means (400), the reception means (3, 4) And a tire pressure detecting device characterized by having an abnormality information transmitting means (410) for transmitting the abnormality information.
The transmitter (2) transmits information on the tire air pressure acquired by the sensing unit (21) for each periodic transmission cycle, and the periodic transmission cycle is set to be equal to or more than a plurality of sampling cycles. The tire air pressure detecting device according to claim 1.
The receiving means (3, 4) stores alarm threshold information used as the alarm condition,
An antenna driver (5) that receives the alarm threshold information from the receiving means (3, 4) and transmits the information to the transmitter (2) attached to each of the plurality of wheels (7a to 7d) through an antenna (51). With
The transmitter (2) receives the alarm threshold information transmitted from the antenna (51), reads out and stores the alarm threshold information, and uses the alarm threshold information as the alarm condition. The tire pressure detecting device according to 1.
The transmitter (2)
Reading means (510, 610, 700) for reading the stored alarm threshold value information;
Determining means (520, 620, 710) for determining whether or not the alarm threshold information read by the reading means (510, 610, 700) is regular data;
Transmission means (530 to 550, 630 to 650, 720 to 730) for setting data indicating the determination result by the determination means (520, 620, 710) and transmitting the data to the reception means (3, 4) The tire pressure detecting device according to claim 3, wherein
The receiving means (3, 4) outputs a request trigger when causing the transmitter (2) to determine whether the alarm threshold information is regular data,
The transmitter (2) has request trigger receiving means (500) for determining that the request trigger has been received, and when the request trigger receiving means (500) determines that the request trigger has been received. After reading the alarm threshold information by the reading means (510), it is determined whether or not the alarm threshold information read by the determination means (520) is regular data. The tire pressure detecting device according to claim 4, wherein
The transmitter (2) performs periodic transmission for transmitting a tire air pressure detection result at every predetermined periodic transmission, and the reading means (610) reads the alarm threshold information at the periodic transmission timing. 5. The tire pressure detecting device according to claim 4, wherein after determining the tire pressure, it is determined whether or not the alarm threshold information read by the determining means (620) is regular data.
The transmitter (2) reads the alarm threshold information by the reading means (700) at every predetermined control period, and then reads the alarm threshold value read by the determination means (710). The tire pressure detecting device according to claim 4, wherein it is determined whether or not the information is regular data.
The transmitter (2)
Reading means (810) for reading the stored alarm threshold information;
Transmission means (830) for setting data relating to the alarm threshold information read by the reading means (810) and transmitting the data to the receiving means (3, 4);
The said receiving means (3, 4) receives the data regarding the said alarm threshold value information which the said transmitter (2) transmitted, and determines whether the said alarm threshold information is regular data. Item 4. The tire pressure detection device according to Item 3.