JP2006123725A - Tire pressure monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately register a tire identification code without erroneous ID registration even if a high radio wave intensity enters a receiver of the own vehicle so that it can be discriminated from a transmitter of the own vehicle or a transmitter of another vehicle. To implement.
A tire pressure monitoring device includes vehicle speed detecting means for detecting a vehicle speed, and the tire identification code registering means transmits a radio wave transmitted from one tire pressure sensor to a tuner with an antenna (1), ( When received at 2), (3), and (4), based on the detected vehicle speed, each received angle exceeds the angle corresponding to the null point among the frames of the received transmission signal. Two certain frames are selected, the received radio wave strength is read from each of the two frames, and the ID is registered based on the two received radio wave strengths.
[Selection] Figure 2

Description

  The present invention belongs to a technical field of a tire pressure monitoring device that determines a mounting position of each tire and individually registers a tire identification code (ID) corresponding to the tire mounting position.

Conventionally, the automatic ID registration logic of a tire pressure monitoring device with a receiving antenna or tuner at each wheel position temporarily stores the reception sensitivity received by each receiver of the vehicle when performing automatic ID registration. Is registered as a candidate for an ID selected by the tuner (see, for example, Patent Document 1).
JP 2003-118333 A

  However, in the conventional tire pressure monitoring device, when the radio wave transmitted from the transmitter of the adjacent vehicle running along with the own vehicle is received by the receiver of the own vehicle, the radio wave transmitted from the transmitter of the adjacent vehicle. When the strength is higher than the strength of the radio wave transmitted from the transmitter of the own vehicle, there is a problem that the tire ID is erroneously registered in the own vehicle.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is from the transmitter of the own vehicle or the transmitter of another vehicle even if a high radio wave intensity enters the receiver of the own vehicle. It is an object of the present invention to provide a tire pressure monitoring device that can determine whether the vehicle is from the above and can perform accurate tire identification code registration without erroneous ID registration.

In order to achieve the above object, in the present invention,
A pressure sensor that is attached to each of a plurality of tires mounted on a vehicle and detects each tire air pressure, and a transmitter that transmits at least the detected tire air pressure together with a tire identification code for each tire by a radio signal. Tire pressure detecting means;
A receiver attached to the vehicle side for receiving a radio signal transmitted from the tire pressure detecting means;
Tire identification code registration means for registering the tire identification code of each tire by storage update to a memory;
In a tire pressure monitoring device equipped with
Vehicle speed detection means for detecting the vehicle speed,
When the tire identification code registering unit receives the radio wave transmitted from the transmitter of one tire air pressure detecting unit by the receiver, the tire identification code registering unit is based on the detected vehicle speed among the frames of the received transmission signal. Select two frames that have a positional relationship that exceeds the angle at which the receiver receives a null point of the receiver, read the received radio wave intensity from each of the two frames, and register the tire identification code based on the two received radio wave intensities It is characterized by that.
Here, the “null point” refers to the angle of the transmitter when the received radio wave intensity is the lowest.

  In the tire pressure monitoring device of the present invention, two frames at a reception angle exceeding the null point are selected from each frame of the transmission signal, and the tire identification code is determined based on the received radio wave intensity of these two frames. In order to register, even if a high radio wave intensity enters the receiver of the vehicle, it is determined whether it is from the transmitter of the vehicle or from the transmitter of another vehicle, and an accurate tire identification code without erroneous ID registration You can register.

  Hereinafter, the best mode for carrying out the tire pressure monitoring apparatus of the present invention will be described based on Example 1 shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall view showing a vehicle to which the tire pressure monitoring device of the first embodiment is applied. As shown in FIG. 1, a left front wheel tire 1, a right front wheel tire 2, a left rear wheel tire 3, and a right Rear wheel tire 4, tire pressure sensors A, B, C, D (tire pressure detection means), tuner with antenna (1), (2), (3), (4) (receiver), tire pressure An alarm controller 5, a display 6, and a low air pressure warning lamp 7 are provided.

  The tire pressure sensors A, B, C, and D are respectively attached to the load valve positions of the road wheels of the tires 1, 2, 3, and 4 of the front and rear wheels, and detect the tire pressure of each tire individually. The ID (tire identification code) for each tire, detected pressure data (tire pressure information), and the like are transmitted to the tuners (1), (2), (3), (4) with antennas by radio signals.

  The antenna-equipped tuners (1), (2), (3), and (4) receive information transmitted from the tire pressure sensors A, B, C, and D and input them to the tire pressure alarm controller 5.

  The tire pressure alarm controller 5 performs ID registration for each tire, displays tire pressure information of the respective tires 1, 2, 3, and 4 of the front and rear wheels specified by the ID registration on the display 6, and front and rear wheels. When it is determined that at least one of the tire air pressures of the tires 1, 2, 3 and 4 has decreased, a lamp lighting command is output to the air pressure decrease warning lamp 6.

  FIG. 2 is a detailed view showing the tire pressure monitoring device of the first embodiment. The tire pressure sensors A, B, C, and D are a pressure sensor 10a (pressure sensor) that detects tire pressure and open (OFF) in a region where the acting centrifugal force is small, and close (ON) in a region where the centrifugal force is large. The centrifugal force switch 10b, the ASIC 10c that is an application specific integrated circuit, the transmitter 10d, and the transmission antenna 10e (transmitter) are respectively configured. Then, with the opening / closing of the centrifugal switch 10b installed to ensure the battery life as a trigger, the transmission interval is very long (for example, 1 hour) in the extremely low speed traveling region including the stop, and short in the region where the vehicle speed is higher than that. The transmission cycle is changed into two stages such as a transmission interval (for example, 1 minute).

  As shown in FIG. 2, the tuners with antennas (1), (2), (3), and (4) include a receiving antenna 11a that receives transmission data from the tire pressure sensors A, B, C, and D. And a tuner 11b which is a receiving circuit. In addition, each transmission data from the tire pressure sensors A, B, C, and D includes information such as a start bit, function code, ID, pressure data, checksum, and frame numbers from 1 to 8. Is included (see FIG. 8).

  As shown in FIG. 2, the tire pressure alarm controller 5 receives a 5V power supply circuit 5a, data received from the tuners 11b, performs various information processing, and performs ID registration. EEPROM 5c, which is a memory that can electrically erase stored information, and display drive circuit 5d that outputs a display drive command for displaying tire air pressure information of each tire 1, 2, 3, 4 to display 6 based on received data; , A warning lamp output circuit 5e for judging the pressure value of the attached tire in the received data and outputting a tire air pressure warning command to the low air pressure warning lamp 7 when the pressure drops, and temporarily storing the ID registration processing information in the buffer RAM (Random Access Memory) 5f.

Next, the operation will be described.
[Automatic ID registration process]
FIG. 3 is a flowchart showing the flow of the automatic ID registration process for each tire executed by the tire pressure alarm controller 5 of the first embodiment. Each step will be described below (corresponding to tire identification code registration means).

  In step S1, for example, the vehicle speed is read from a wheel speed sensor or the like, and the process proceeds to step S2 (corresponding to vehicle speed detection means).

  In step S2, an automatic ID registration timer is started, and the process proceeds to step S3.

  In step S3, it is determined whether data of any of the four pressure sensors 10a has been received. If YES, the process proceeds to step S4. If NO, the process proceeds to step S1.

  In step S4, it is determined whether or not the vehicle speed read in step S1 is higher than the vehicle speed threshold value of 100 km / h. If YES, the process proceeds to step S5. If NO, the process proceeds to step S17.

  In step S5, the order of tuners with the highest reception level of the RSSI value read twice in one frame of the received data (when shifted from step S4) or the order of tuners with the high reception level of the two selected RSSI values (step It is determined whether or not they are the same). If YES, the process moves to step S6. If NO, the process moves to step S16.

  In step S6, it is determined whether or not the difference between the RSSI values of the tuner having the first reception level (maximum value) and the tuner having the second reception level is 0.3 V or more, for example. If YES, the process proceeds to step S7. If NO, the process proceeds to step S16.

  In step S7, it is determined whether or not the RSSI value of the tuner with the highest reception level is 2.2V or higher. If YES, the process proceeds to step S8, and if NO, the process proceeds to step S16.

  In step S8, the received data (including ID and RSSI value) is stored in a buffer (temporary storage device), and the process proceeds to step S9.

  In step S9, the process waits until the next data is received. After receiving the data, the process proceeds to step S10.

  In step S10, it is determined whether the automatic ID registration timer is 7 minutes or longer. If YES, the process proceeds to step S11. If NO, the process proceeds to step S1.

  In step S11, the sampling process for automatic ID registration is terminated, and the process proceeds to step S12.

  In step S12, the received pressure data is referred to and it is determined whether or not the tire pressure is normal. If YES, the process proceeds to step S13. If NO, the process proceeds to step S15.

  In step S13, an ID having an average RSSI value is assigned to the tuner, and the ID is registered (corresponding to tire identification code registration means), and the process proceeds to step S14.

  In step S14, monitoring of the pressure value is started with the registered ID, and the process proceeds to return.

  In step S15, the warning lamp 7 is turned on, the driver is warned of a pressure abnormality, and the routine proceeds to return.

  In step S16, data is discarded from the buffer, and the process proceeds to step S1.

  In step S17, it is determined whether or not the vehicle speed matches any of 25km / h, 37.5km / h, 50km / h, and 75km / h shown in FIG. If YES, the process proceeds to step S18, and if NO, the process proceeds to step S20.

  FIG. 4 is a table in which the wheel angle characteristics for each wheel are calculated when the received signal starts with frame number 1 (pattern 1 in FIG. 5). When the vehicle speed is any of the above values, as shown in FIG. 4, one of the frames has the same angle. Therefore, it is necessary not to select frames having the same angle.

  Here, as shown in FIG. 5, since there are eight reception signal start patterns, the frame group having the same angle at a specific vehicle speed also changes according to the frame number to be started. The description will be omitted assuming that the frame is always received from frame number 1. In addition, the vertical direction of FIG. 5 shows the distance between frames.

  In step S18, the frame numbers received during one transmission are compared, the same group is sorted, and the process proceeds to step S19.

  In step S19, the RSSI value of the frame number representing the frame number group in FIG. 4 is read and the RSSI value of the frame number different from that of the frame group is read, and the process proceeds to step S21.

  In step S20, two frames are selected from each frame received during one transmission, RSSI values are read from the two frames, and the process proceeds to step S21. At this time, it is assumed that the two frames to be selected are in a positional relationship in which the mutual reception angle exceeds the angle at which the null point is reached based on the vehicle speed and the distance between the frames.

  In step S21, it is determined whether there are two or more frames per second. If YES, the process proceeds to step S5. If NO, the process proceeds to step S22.

  In step S22, data is discarded from the buffer, and the process proceeds to step S1.

[Received data example]
For example, when a radio wave is transmitted from the transmitter of the tire pressure sensor A set on the left front wheel of the host vehicle while traveling at a vehicle speed of 50 km / h, FIG. 6 shows data for one transmission (8 frames) at 500 ms. FIG. 7 shows an example of one frame data of a transmitter, reception intensity (= radio wave intensity) characteristics and a radio wave intensity reading position (RSSI (1) and RSSI (2)) in a tuner with an antenna. FIG.

  Here, when the transmission data from the transmitter of the tire pressure sensor A is received by the tuner with the antenna, the position of the tuner with the antenna is influenced by the mounting position of the vehicle body, and the radio wave intensity is apparent from the broken line in FIG. There is a characteristic that the level changes. In Fig. 7, the first RSSI (1) measured by the tuner with the antenna and the last RSSI value (2) measured by the tuner with the antenna are about 15 ms moving by transmitting one frame data at a vehicle speed of 50 km / h. Data at a position with a time difference.

  FIG. 8 is a diagram showing, as a radar chart, the radio wave intensity level (reception intensity level) received by the tuners with antennas (1) and (4) when the tire is rotated once. In FIG. 8, the first RSSI value (1) measured by the tuners with antennas (1) and (4) and the last RSSI value (2) measured by the tuners with antennas (1) and (4) are: The data is at a position where there is an angle difference (about 35 °) that fluctuates when one frame data is transmitted at a vehicle speed of 50 km / h.

[Automatic ID registration]
(When vehicle speed exceeds 100km / h)
For example, when traveling at a high speed exceeding 100 km / h, the process proceeds from step S1 to step S2 in the flowchart of FIG. 3, and the automatic ID registration timer starts. Then, the flow proceeds from step S3 → step S4 → step S5 → step S6 → step S7 → step S8 → step S9 → step S10. In other words, when the signal output level (RSSI value) is read twice from one frame of the transmission signal, the difference between the first (maximum value) and second value is greater than the threshold (0.3V) ID only.

  Therefore, in Example 1, the maximum RSSI value is greater than or equal to the threshold at a time interval within one frame, and the difference between the maximum RSSI value (first value) and the second value is greater than or equal to the threshold. If both conditions are satisfied, the transmission data from the tire pressure sensor set for the tire of the own vehicle is trusted and set as an ID registration candidate. That is, a high-accuracy ID registration candidate is obtained by using the maximum value of the reception level received by a tuner that is close to the transmitter that transmits data and has high sensitivity.

  Incidentally, for example, when a radio wave is transmitted from the transmitter of the tire pressure sensor set on the right front wheel of the adjacent vehicle, the tuner (1), (4) with the antenna of the own vehicle is connected to the tire pressure sensor of the adjacent vehicle. When the above data is received, as shown by the broken line characteristic in FIG. 8, the tuners (1) and (4) with the antenna of the own vehicle instantaneously receive the data having a large radio wave intensity level. However, conditions A and B satisfying that the maximum value of the first RSSI value (1) is greater than or equal to the threshold value and the difference between the first and second values of the first RSSI value (1) is greater than or equal to the threshold value. Even if, the conditions C and D that the maximum value of the last RSSI value (2) is equal to or greater than the threshold and the difference between the first and second values of the last RSSI value (2) is equal to or greater than the threshold. Since the ID registration candidate data is discarded (step S16), erroneous ID registration is prevented even if a strong radio wave is transmitted from the adjacent vehicle.

(When the vehicle speed is 100 km / h or less)
When the speed is 100 km / h or less, the process proceeds from step S4 to step S17 in the flowchart of FIG. 3, where the vehicle speed does not match any of 25km / h, 37.5km / h, 50km / h, or 75km / h. In step S17, the process proceeds from step S20 to step S21, and RSSI values of two frames are selected.

  On the other hand, when the vehicle speed is any one of 25 km / h, 37.5 km / h, 50 km / h, and 75 km / h, the process proceeds from step S17 to step S18 → step S19 → step S21. An RSSI value of a frame number that is a representative of the frame number group is read, and an RSSI value of a frame number different from that of the frame group is read.

  In step S21, if there are two or more frames per second, the process proceeds to step S5, the output level (RSSI value) of the two frames is read, and the difference between the two RSSI values is a threshold value (0.3V). Only when there is a difference as described above, it is stored in the buffer as a candidate for ID registration. Therefore, the transmitter corresponding to the tuner is identified based on the output level of the transmission signal of the transmitter, and ID registration is performed. Therefore, it can be reliably determined that the transmitter corresponds to the tuner of the own vehicle, and erroneous ID registration occurs. Can be prevented.

  On the other hand, if there are no more than two frames per second in step S21, the process proceeds to step S22 and the received data is discarded. That is, received data in a very low speed region that does not exist for two frames or more in one second is difficult to be transmitted by the transmitter due to the strength of the received radio wave. Therefore, discarding the data can prevent erroneous ID registration.

[Prior art issues]
Japanese Patent Application Laid-Open No. 2003-118333 describes a technique in which the maximum value of reception sensitivity is selected as a candidate for an ID selected by the tuner, but when the radio wave intensity received from a vehicle adjacent to the own vehicle is high. There are cases where the ID registration is mistaken.

  As a solution to this, the output level of the signal is read twice or more from one frame of the transmission signal, the maximum value and the second largest value are compared, and only when the difference is equal to or greater than a predetermined value, the ID of the registered wheel By doing so, it is possible to reliably identify the transmitter corresponding to the corresponding tuner of the own vehicle, thereby preventing erroneous ID registration.

  However, in this conventional technology, when the vehicle speed is high, for example, when traveling at over 100 km / h, the difference in rotation angle for receiving two signals is 30 ° or more, so the null point at which the reception level is the lowest However, when the vehicle speed is low, the difference in rotation angle for receiving the two signals is 10 ° or less, and both signals are within the null point (10 ° However, there is a problem that ID registration cannot be performed.

[Frame selection action according to vehicle speed]
On the other hand, in the first embodiment, data indicating the frame number is added to each frame from 1 to 8 of one transmission data, and the radio wave intensity is compared so as to avoid a null point according to the vehicle speed. Select two frames.

  FIG. 9 shows an example of the data arrangement of one frame, and FIG. 10 shows the received intensity reading position of each frame. In the first embodiment, data representing frame numbers from 1 to 8 (for example, 000 to 111 in a 3-bit binary number) is added between the pressure data and the checksum. When the vehicle speed is 100 km / h or less, two frames having a positional relationship in which the mutual reception angle exceeds the angle corresponding to the null point (less than 10 °) are selected from the frame numbers, and the two frames ID registration candidates are based on the received radio wave intensity.

  As a result, even in a low vehicle speed range (for example, 30 km / h or less in Japanese Patent Laid-Open No. 2003-118333), a transmitter ID corresponding to the corresponding tuner of the own vehicle can be reliably determined by avoiding a null point. The vehicle speed range where puncture warning is possible can be expanded, and safety can be improved. Further, since the pressure value can be displayed on the display 6 even in a low vehicle speed range, the merchantability is also improved.

[Frame selection action when frame reception angles overlap]
When the above method is used, when a plurality of frames have the same angle at the characteristic vehicle speed, if the frames having the same angle are selected, the received radio wave intensity cannot be compared.

  As a countermeasure, in Example 1, as shown in FIG. 11, for example, when the vehicle speed at which the frame numbers 3, 5, and 8 have the same angle is 25 km / h, do not select two of them at the same time. To. For example, when frame number 3 is selected, frames other than frame numbers 5 and 8 are selected.

  By the way, at 50 km / h, frame numbers 3, 4, and 5 have the same angle, and 1, 2, 6, and 8 have the same angle (FIG. 12). When vehicle speed is 75 km / h, frame number 2 , 3, 5, 6, 7 and 8 have the same angle (FIG. 13). When the vehicle speed is 37.5 km / h, frame numbers 5 and 7 are the same, and frame numbers 2, 3, 6, and 8 are the same. The numbers are the same (FIG. 14). Therefore, by not selecting the same angles at these vehicle speeds, it is possible to prevent the comparison of the received radio wave strengths from being disabled by selecting frames of the same angle at the specific vehicle speed.

Next, the effect will be described.
In the tire pressure monitoring apparatus of the first embodiment, the following effects can be obtained.

  (1) A pressure sensor 10a that is attached to each of a plurality of tires 1, 2, 3, and 4 mounted on a vehicle and detects each tire air pressure, and at least the detected tire air pressure is converted into a radio signal together with the ID of each tire. Tire pressure sensors A, B, C, and D having a transmitter 10d and a transmitting antenna 10e for transmitting, and a radio signal attached to the vehicle side and transmitted from the tire pressure sensors A, B, C, and D Tuners with antennas (1), (2), (3), (4), and tire identification code registration means for registering the IDs of the tires 1, 2, 3, 4 by storing and updating the EEPROM 5c. The tire pressure monitoring device includes a vehicle speed detecting means for detecting the vehicle speed, and the tire identification code registering means transmits a radio wave transmitted from one tire pressure sensor and transmitted from 10d to the antenna. When receiving with the tuner (1), (2), (3), (4), each received angle corresponds to the null point based on the detected vehicle speed in each frame of the received transmission signal Select two frames that are in a positional relationship that exceeds the angle to be read, read the received radio field strength from each of the two frames, and register the ID based on the two received radio field strengths. Even if an error occurs, it is possible to determine whether it is from the transmitter of the own vehicle or from the transmitter of another vehicle, and accurate tire identification code registration without erroneous ID registration can be performed.

  (2) The tuners with antennas (1), (2), (3), (4) transmit each frame of the transmission signal with data representing a different frame number, and the tire identification code registration means Since two frames are selected based on the received frame number, two frames that avoid a null point can be easily determined from the frame number based on the distance between the frames and the vehicle speed that are apparent in advance.

  (3) The tire identification code registration means obtains a frame number having the same reception angle based on the vehicle speed and the frame interval, the frame to which the frame number having the same reception angle is assigned, and other reception angles. Therefore, selection between frames having the same reception angle can be avoided, and erroneous ID determination can be prevented.

  (4) Since the tire identification code registration means is used as an ID registration candidate only when the relationship between the received radio wave strengths of the two selected frames is similar to each other, the buffer capacity for temporarily storing the ID registration candidate Even if high electric field strength enters the tuner (1), (2), (3), (4) with the antenna of the own vehicle, the transmitter from the own vehicle or the transmitter of another vehicle Therefore, accurate tire identification code registration without erroneous ID registration can be performed.

  (5) When the detected vehicle speed is higher than a preset vehicle speed threshold (100 km / h), the tire identification code registering means calculates the received radio wave intensity at least twice from one frame of the transmission signal at different times. Only when the relationship between these two received radio wave intensities is similar to each other, the tuner is equipped with the antenna of the own vehicle while reducing the buffer capacity for temporarily storing the ID registration candidates, since the ID registration candidates are used. Even if high radio field strength enters (1), (2), (3), (4), it is determined whether it is from the transmitter of the own vehicle or from the transmitter of another vehicle, and there is no erroneous registration Accurate ID registration can be performed.

(Other examples)
As described above, the tire pressure monitoring device of the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and is described in each claim of the claims. Design changes and additions are allowed without departing from the scope of the present invention.

  For example, in the embodiment, for example, in the first embodiment, an example is shown in which it is determined that the data is reliable as an ID registration candidate by satisfying the conditions A and B and the conditions C and D. Instead of the condition, it may be confirmed whether the permutation of the level received first by the tuner with the antenna matches the permutation of the level received last by the frame.

  In the embodiment, in step S13, an example is shown in which the ID whose reception level average value is the maximum value is newly registered as an ID registration, but the ID whose reception level integrated value is the maximum value is ID. You may make it newly register as what should be registered.

  In the embodiment, the receiver (tuner) is set in the vicinity of each of the plurality of tires by the number of tires, but the number of receivers may be one or two. In this case, it is possible to recognize which tire the signal is from by storing the characteristics of the received radio wave intensity according to the rotation of the tire for each tire.

  In the embodiment, when the vehicle speed exceeds 100 km / h, the example of reading the received radio wave intensity twice in one frame of the transmission signal is shown. However, even if the vehicle speed exceeds 100 km / h, the transmission signal The received radio wave intensity may be read from two of the frames. In this case, when the vehicle speed is 150 km / h, the reception angles of all the frames are at the same position (see FIG. 13). Therefore, when the vehicle speed is 150 km / h, the data is discarded.

  In the embodiment, the null point is the point at which the reception level is the lowest, but this is not a limitation, and the reception level is relatively lowered, and it cannot be determined whether the transmission is from the transmitter of the own vehicle or from another vehicle. It can also be applied to situations where a situation occurs. Further, a plurality of null points may be present during one round of the tire.

  In the embodiment, the tire pressure monitoring device in a vehicle equipped with four tires such as a passenger car is shown, but the tire pressure monitoring device in a small vehicle equipped with three tires or a large vehicle equipped with five or more tires may be used. Can be applied.

1 is an overall view showing a vehicle to which a tire pressure monitoring device according to a first embodiment is applied. 1 is a detailed view showing a tire pressure monitoring device of Example 1. FIG. 6 is a flowchart showing a flow of automatic ID registration processing for each tire executed by the tire air pressure alarm controller 5 according to the first embodiment. It is a table | surface which shows the wheel angle characteristic for every wheel. It is a figure which shows the start pattern of a received signal. The example of data of 1 transmission (8 frames) in 500 ms from a transmitter in Example 1 is shown. In Example 1, it is a figure which shows the 1st frame data example of a transmitter, the receiving intensity (= radio wave intensity) characteristic in a tuner with an antenna, and the reading position (RSSI (1) and RSSI (2)) of a radio wave intensity. It is the figure which showed the radio wave intensity level (reception intensity level) which tuner (1), (4) with an antenna received when rotating the tire 1 time as a radar chart. It is an example of a data arrangement of 1 frame. It is a figure which shows the receiving intensity reading position of each flame | frame. It is a figure which shows the frame number which becomes the same angle at the vehicle speed of 25 km / h. It is a figure which shows the frame number which becomes the same angle at the vehicle speed of 50 km / h. It is a figure which shows the frame number which becomes the same angle at the vehicle speed of 75 km / h. It is a figure which shows the frame number which becomes the same angle at the vehicle speed of 37.5km / h.

Explanation of symbols

1 Left front wheel tire 2 Right front wheel tire 3 Left rear wheel tire 4 Right rear wheel tire A, B, C, D Tire pressure sensor (tire pressure detection means)
(1), (2), (3), (4) Tuner with antenna (receiver)
5 Tire pressure alarm controller 5c EEPROM
5f RAM
6 Display 7 Low air pressure warning lamp 10a Pressure sensor 10b Centrifugal switch 10c ASIC
10d Transmitter (transmitter)
10e Transmitting antenna (transmitter)
11a receiving antenna 11b tuner

Claims (5)

A pressure sensor that is attached to each of a plurality of tires mounted on a vehicle and detects each tire air pressure, and a transmitter that transmits at least the detected tire air pressure together with a tire identification code for each tire by a radio signal. Tire pressure detecting means;
A receiver attached to the vehicle side for receiving a radio signal transmitted from the tire pressure detecting means;
Tire identification code registration means for registering the tire identification code of each tire by storage update to a memory;
In a tire pressure monitoring device equipped with
Vehicle speed detection means for detecting the vehicle speed,
When the tire identification code registering unit receives the radio wave transmitted from the transmitter of one tire air pressure detecting unit by the receiver, the tire identification code registering unit is based on the detected vehicle speed among the frames of the received transmission signal. Select two frames that have a positional relationship that exceeds the angle at which the receiver receives a null point of the receiver, read the received radio wave intensity from each of the two frames, and register the tire identification code based on the two received radio wave intensities A tire pressure monitoring device characterized by that. In the tire pressure monitoring device according to claim 1,
The transmitter adds data representing a different frame number to each frame of the transmission signal and transmits the frame,
The tire pressure monitoring device is characterized in that the tire identification code registration means selects two frames based on the received frame number. In the tire pressure monitoring device according to claim 2,
The tire identification code registration means obtains a frame number having the same reception angle based on the vehicle speed and the frame interval, a frame to which the frame number having the same reception angle is assigned, and a frame having another reception angle A tire pressure monitoring device, wherein a frame with a number is selected. In the tire pressure monitoring device according to any one of claims 1 to 3,
The tire pressure monitoring device is characterized in that the tire pressure identification code registration means is a tire pressure identification code registration candidate only when the relationship between the received radio wave intensities of the two selected frames is similar to each other. The tire pressure monitoring device according to any one of claims 1 to 4,
When the detected vehicle speed is higher than a preset vehicle speed threshold, the tire identification code registering unit reads the received radio wave intensity at least twice at different times from one frame of the transmission signal, and the two received radio waves A tire pressure monitoring apparatus characterized in that it is a candidate for registration of a tire identification code only when the relationship in strength is similar to each other.

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