JP4458273B2 - Tire pressure monitoring system - Google Patents

Description

  The present invention relates to a tire air pressure monitoring system for monitoring the air pressure of a tire of a vehicle or the like.

  The tire pressure monitoring system is a receiver (ECU) installed on a vehicle body that receives air pressure data periodically transmitted by radio (radio waves) from a tire pressure sensor (hereinafter abbreviated as a tire sensor) installed in a tire. ), And if the received air pressure value is lower than the predetermined value, the warning light installed in the instrument panel (hereinafter abbreviated as instrument panel) is turned on to warn the driver. . Each tire sensor has a unique ID number, and the relationship between the ID number of each tire sensor and the position of the attached tire is registered in advance in the receiver so that the received air pressure data can be obtained for any tire. It becomes possible to recognize. In addition, even if the set air pressure differs between the front and rear wheels, and the predetermined air pressure value to be warned differs between the front and rear wheels, the receiver recognizes whether the front wheel or the rear wheel from the ID number, so that the air pressure can be reduced correctly. A warning can be issued.

JP 2004-149093 A

  Depending on the wear state of the tire, the tire may be mounted with its position rotated. When the tire position is rotated, the relationship between the ID number registered in the receiver and the mounting position is not correct, and a warning of low air pressure cannot be issued correctly. Therefore, when the tire position is rotated, it is necessary to re-register the ID number and the mounting position, but this operation is troublesome.

  Some conventional tire pressure monitoring systems are provided with a plurality of receivers (radio wave intensity sensors), and the radio wave intensity from each tire sensor in each radio wave intensity sensor is compared to determine the tire mounting position. However, each tire sensor has a variation in its radio wave output. Further, the radio wave intensity sensor also has a variation in its reception sensitivity. In addition, between the tire sensor and the radio wave intensity sensor due to a shield such as a vehicle body. Since the amount of radio wave attenuation also varies, there is a risk that the tire mounting position cannot be accurately determined. In order to avoid such a situation, it is necessary to determine the installation position of the radio wave intensity sensor with sufficient consideration of these variations, the installation position of the radio wave intensity sensor is limited, and the degree of freedom in design is small. It became a problem of becoming.

  The present invention has been made in view of the above problems, and even if there are variations in radio wave output, reception sensitivity, radio wave attenuation, etc., the relationship between the tire ID number and the mounting position is automatically detected correctly, and the air pressure decreases. It is an object of the present invention to provide a tire pressure monitoring system with a high degree of freedom in installation position.

A tire pressure monitoring system according to a first invention for solving the above-mentioned problem is as follows.
Transmitting means that is provided in each tire of the vehicle and transmits an identification signal that can individually identify each tire, and a state signal that indicates the state of each tire including air pressure;
A first receiving means provided in a vehicle for detecting a radio field intensity of a signal from the transmitting means;
The second receiving means, which is installed away from the first receiving means in the front-rear direction of the vehicle and detects the radio field intensity of the signal from the transmitting means;
The identification signal from the transmitting means received by the first receiving means or the second receiving means while receiving the radio wave intensity detected by the first receiving means and the radio wave intensity detected by the second receiving means. And signal processing means to which the status signal is input,
The signal processing means includes
Of the radio field intensity of each transmission means detected by the first reception means, the radio field intensity from any transmission means, and among the radio field strengths of each transmission means detected by the second reception means, the arbitrary transmission means For each combination with radio field strength from different transmission means, find the sum for each combination and compare the sum of each combination to identify the front and rear positions of each tire corresponding to each transmission means. Then, the condition of each tire is monitored by the condition signal for the identified tire.

A tire pressure monitoring system according to a second invention for solving the above-described problems is as follows.
A transmission means provided on each tire of the vehicle, for transmitting an identification signal capable of individually identifying each tire, and a state signal indicating the state of each tire including air pressure and the rotation direction of the tire;
A first receiving means provided in a vehicle for detecting a radio field intensity of a signal from the transmitting means;
The second receiving means, which is installed away from the first receiving means in the front-rear direction of the vehicle and detects the radio field intensity of the signal from the transmitting means;
The identification signal from the transmitting means received by the first receiving means or the second receiving means while receiving the radio wave intensity detected by the first receiving means and the radio wave intensity detected by the second receiving means. And signal processing means to which the status signal is input,
The signal processing means includes
Based on the information on the rotation direction of the state signal, for the transmission means determined to rotate in the same direction,
The radio wave intensity from any one transmission means detected by the first reception means and the other one transmission means rotating in the same direction as the arbitrary one transmission means detected by the second reception means The sum of the radio field intensity is the sum of the radio field intensity from the other one transmission unit detected by the first reception unit and the radio field intensity from the arbitrary one transmission unit detected by the second reception unit. If it is larger, it is determined that the arbitrary one transmission means is arranged on the first reception means side, and the other one transmission means is arranged on the second reception means side, and each of the transmission means corresponding to each transmission means is determined. The front and rear positions of the tire are specified, and the state of each tire is monitored by the state signal for the specified tire.

A tire pressure monitoring system according to a third aspect of the present invention for solving the above problem is as follows.
Transmission means provided on each of the four tires provided on the front, rear, left and right sides of the vehicle, for transmitting an identification signal capable of individually identifying each tire, and a state signal indicating the state of each tire including air pressure,
A first receiving means provided in a vehicle for detecting a radio field intensity of a signal from the transmitting means;
The second receiving means, which is installed away from the first receiving means in the front-rear direction of the vehicle and detects the radio field intensity of the signal from the transmitting means;
The identification signal from the transmitting means received by the first receiving means or the second receiving means while receiving the radio wave intensity detected by the first receiving means and the radio wave intensity detected by the second receiving means. And signal processing means to which the status signal is input,
The signal processing means includes
Of the radio field intensity of each transmission means detected by the first reception means, among the radio field intensity from any two transmission means and the radio field intensity from each transmission means detected by the second reception means, the arbitrary For the combination with the radio field intensity from the other two transmission means different from the two transmission means, the sum for each combination is obtained and the combination that maximizes the sum is obtained. The two transmitting means having the radio wave intensity at the first receiving means are on the first receiving means side, and the other two transmitting means having the radio wave intensity at the second receiving means are the second receiving means. The front and rear positions of the tires corresponding to the transmission means are identified, and the state of each tire is monitored by the state signal for the identified tire.

A tire pressure monitoring system according to a fourth invention for solving the above-described problem is
In the tire pressure monitoring system according to the third invention,
The transmission means transmits information indicating the rotation direction of each tire as a status signal of each tire,
The signal processing means identifies a left wheel and a right wheel of a tire based on traveling direction information indicating a traveling direction of a vehicle and information indicating a rotation direction of the state signal.

  According to the present invention, even if there are variations in radio wave output, reception sensitivity, radio wave attenuation, etc., the relationship between the tire ID number and the mounting position can be detected automatically and correctly, even when the tire position is rotated. Can properly warn of air pressure drop. Further, the driver's operation associated with the rotation of the tire position becomes unnecessary, and convenience is improved. In addition, since the configuration is not easily affected by variations in radio wave output, reception sensitivity, radio wave attenuation, etc., the system installation position, especially the restriction on the installation position of the radio wave sensor, is reduced and design flexibility is improved. Can do.

The tire pressure monitoring system according to the present invention uses a plurality of radio wave sensors installed at different positions to detect the radio wave intensity from each tire sensor, and the radio wave from any tire sensor detected by one radio wave sensor. For the combination of the intensity and the radio wave intensity from another tire sensor that is different from an arbitrary tire sensor detected by the other radio wave sensor, radio wave output and reception are obtained by comparing the sums for each combination. Even if there are variations in sensitivity, radio wave attenuation, etc., the relationship between the tire ID number and the mounting position is automatically detected correctly, the position of each tire is specified, and the state of each tire is monitored.
Below, some of the embodiments of the tire pressure monitoring system according to the present invention are shown, and a detailed description thereof will be given with reference to FIGS.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a tire pressure monitoring system according to the present invention. FIG. 1 (a) shows an arrangement of a radio wave sensor and a tire sensor, and FIG. FIG. 1C illustrates a configuration example of the control device and the radio wave sensor.

  As shown in FIG. 1 (a), the tire pressure monitoring system according to the present embodiment is installed in the front wheel T1 and the rear wheel T2, and includes an identification signal such as an ID number and an air pressure value that can individually identify each tire. The tire sensors S1 and S2 that periodically transmit signals including these, such as status signals indicating the state of each tire, by radio (radio waves), and the radio wave intensity values from the tire sensors S1 and S2 installed in the vehicle 10 A plurality of (two in FIG. 1) radio wave sensors D1 and D2 that detect and receive signals including air pressure values and ID numbers from the tire sensors S1 and S2, and radio wave intensity values and identification signals from the radio wave sensors D1 and D2. And a control device 1 that receives a state signal and performs predetermined arithmetic processing.

  The present invention can be applied to any configuration as long as it has a plurality of radio wave sensors at different positions in the longitudinal direction of the vehicle. Here, as a representative configuration of the control device and the radio wave sensor, a configuration example as shown in FIGS. 1B and 1C will be shown and described.

  As shown in FIG. 1B, the radio wave sensors D1 and D2 are arranged independently of the control device 1, and the radio wave sensor D1 includes an antenna 3 that receives radio waves from the tire sensors S1 and S2, and The sensor 3 includes a detection unit 5 that detects a radio wave intensity value, an air pressure value, and an ID number at the antenna 3, and the radio wave sensor D 2 includes an antenna 8 that receives radio waves from the tire sensors S 1 and S 2, and The detector 9 detects the air pressure value and the ID number, and transmits the detected radio field intensity value, air pressure value, and ID number to the control device 1. And the control apparatus 1 has the calculating part 6, In the calculating part 6, the air pressure value from tire sensor S1, S2, the ID number, the radio wave intensity value, and the radio wave sensor D2 transmitted from the radio wave sensor D1. Predetermined arithmetic processing is performed using the transmitted air pressure values, ID numbers, and radio wave intensity values from the tire sensors S1 and S2.

  Moreover, in FIG.1 (c) which shows the other structural example of a control apparatus and a radio wave sensor, the tire pressure monitoring system is the structure which has one control apparatus 1 and one radio wave sensor D2. Here, the same components as those shown in FIG. 1B are denoted by the same reference numerals, and redundant description is omitted.

  The control device 1 detects an antenna 3, a radio wave intensity value, an air pressure value, and an ID number at the antenna 3, a detection unit 5 that transmits the detected radio wave intensity value, an air pressure value, and an ID number, and the detection unit 5 and the radio wave And an arithmetic unit 6 that performs predetermined arithmetic processing using the radio wave intensity value, the air pressure value, and the ID number transmitted from the sensor D2. That is, the control device 1 in FIG. 1C is obtained by adding the detection unit 5 having the antenna 3 to the control device 1 in FIG. 1B, and is configured by integrating the control device and one radio wave sensor. It is. As described above, a plurality of (two in FIG. 1C) are included in the system by the portion including the antenna 3 and the detection unit 5 (hereinafter referred to as a radio wave sensor D1 for convenience) and the radio wave sensor D2. ) Radio wave sensor. Here, since the detection unit 5 having the antenna 3 is provided in the control device 1, the configuration of the system can be made compact.

  In the configuration shown in FIGS. 1B and 1C, one radio wave sensor D1 is disposed on the front wheel T1 side (relative to the vehicle front side), and the other radio wave sensor D2 is disposed on the rear wheel T2 side (relative). The radio wave intensity values detected by the radio wave sensors D1, D2 are transmitted to the control device 1 side, and the radio wave intensity values from the tire sensors S1, S2 at the radio wave sensors D1, D2 are calculated. By performing predetermined calculation processing at 6, the front and rear wheels at the position of the mounted tire can be reliably recognized.

  The details will be described with reference to the flowchart shown in FIG. 2. In the radio wave sensor D1 arranged on the front side of the vehicle, the radio wave intensity value of the signal from the tire sensor S1 mounted on the front wheel T1 is set to R1f and the rear wheel T2 is mounted. The radio wave intensity value of the signal from the tire sensor S2 is R2f, and the radio wave intensity value of the signal from the tire sensor S1 attached to the front wheel T1 is R1r and the rear wheel T2 in the radio wave sensor D2 disposed on the rear side of the vehicle. If the radio wave intensity value of the signal from the tire sensor S2 attached to R2r is R2r (see FIG. 1A), the radio wave intensity value R1f of one tire sensor S1 detected by the radio wave sensor D1 and the radio wave sensor D2 are detected. The sum of the radio wave intensity value R2r of the other tire sensor S2 and the radio wave intensity value R2f of the other tire sensor S2 detected by the radio wave sensor D1 and the radio wave sensor D2 If it is greater than the sum of the detected radio wave intensity value R1r of one tire sensor S1, it can be determined that one tire sensor S1 is disposed on the radio wave sensor D1 side and the other tire sensor S2 is disposed on the radio wave sensor D2 side, From this, it can be recognized that the tire sensor S1 is attached to the front wheel and the tire sensor 2 is attached to the rear wheel. When the received air pressure value is lower than a predetermined value, the warning light 7 installed in the instrument panel is turned on to warn the driver of the corresponding tire.

  Here, the details of the predetermined calculation process of the present embodiment performed by the calculation unit 6 of the control device 1, that is, the tire position recognition procedure will be described with reference to the flowchart of FIG.

<Step S1>
The tire position recognition procedure starts when the ignition (IG) is turned on.

<Step S2>
It is determined whether the signal of the ID number registered in the own vehicle has been received. If the signal is the ID number registered in the own vehicle, the process proceeds to step S3. Otherwise, the process returns to step S1. This has the purpose of eliminating signals from tire sensors of other vehicles.

<Step S3>
It is determined whether or not the air pressure value included in the received signal is equal to or lower than the warning threshold value. Proceed to step S5.

<Step S4>
From the storage of the arrangement positions of the tire sensors S1 and S2 with respect to the tire positions (see steps S8 and S9 described later), the instrument panel warning lamp 7 is turned on for the tire at the corresponding position to display the air pressure warning. At this time, if the set air pressure is different between the front wheel T1 and the rear wheel T2, it is recognized from the storage of the arrangement positions of the tire sensors S1, S2 with respect to the tire position whether the warning object is the front wheel T1 or the rear wheel T2. If it is the front wheel T1, it is compared with the set air pressure value of the front wheel T1 that should be warned, and if it is the rear wheel T2, it is compared with the set air pressure value of the rear wheel that should be warned. ing.

<Step S5>
Radio wave intensity values R1f, R1r, R2f, R2r are stored for the received tire ID numbers, and the process proceeds to step S6. Here, R1f is a radio wave intensity value at the front side radio wave sensor D1 from the tire sensor S1, and R1r is a radio wave intensity value at the rear side radio wave sensor D2 from the tire sensor S1. R2f is a radio wave intensity value at the front side radio wave sensor D1 from the tire sensor S2, and R2r is a radio wave intensity value at the rear side radio wave sensor D2 from the tire sensor S2.

<Step S6>
The procedure steps S1 to S5 are repeated until the radio field intensity values from both the tire sensor S1 and the tire sensor S2 are stored.

<Step S7>
The following equation (1) is calculated. If the equation (1) is satisfied, the process proceeds to step S8. If the equation (1) is not satisfied, the process proceeds to step S9.
(R1f + R2r)> (R2f + R1r) (1)

  That is, in step S7, the radio wave intensity from any tire sensor out of the radio wave intensity from the tire sensors S1 and S2 detected by the radio wave sensor D1, and the radio wave intensity of the tire sensors S1 and S2 detected by the radio wave sensor D2 are determined. Among them, for the combination with the radio wave intensity from another tire sensor different from the arbitrary tire sensor described above, the sum for each combination is obtained and the sum of each combination is compared. As shown in steps S8 and S9, the front and rear positions of the tires corresponding to the tire sensors S1 and S2 are specified.

<Step S8>
The tire sensor S1 is determined to be the front wheel T1 side, and the tire sensor S2 is determined to be the rear wheel T2 side, stored, and the process returns to step S1.

<Step S9>
The tire sensor S2 is determined to be on the front wheel T1 side, and the tire sensor S1 is determined to be on the rear wheel T2 side, stored, and the process returns to step S1.

  That is, in summary, in this embodiment, as a method for determining the position of the mounted tire, two radio wave sensors D1 and D2 are used, and the sum (R1f + R2r) and (R1r + R2f) of radio wave intensity in each radio wave sensor D1 and D2 are compared. Thus, the front wheel and the rear wheel are determined.

  Here, the effectiveness of the present invention will be described by making a comparison with the conventional example using FIG.

  In the conventional tire pressure monitoring system, only one radio wave sensor is provided in front of or behind the vehicle body. For example, when one radio wave sensor is provided in front of the vehicle, a tire sensor having a high radio wave intensity is recognized as the front wheel side, and a weak tire sensor is recognized as the rear wheel side. In such a system, taking into account manufacturing variations in the radio wave output of tire sensors, even if a tire sensor with weak radio wave output is attached to the front wheel and a tire sensor with strong radio wave output is attached to the rear wheel, the radio wave intensity from the tire sensor on the front wheel However, it is necessary to install the radio wave sensor at a position where the radio wave intensity from the tire sensor on the rear wheel becomes weak, so the installation position of the radio wave sensor becomes a very limited position, and the degree of design freedom is increased. It was a small one.

  On the other hand, in the tire air pressure monitoring system according to the present invention, at least two radio wave sensors having different positions in the front-rear direction of the vehicle are provided, and combinations of radio wave intensity values of the tire sensors in the radio wave sensors are combined. By calculating the sum of the two, the variation in the radio wave output of the tire sensor is canceled out in the calculation formula, so that it is not necessary to consider the variation in the radio wave output of the tire sensor when installing the radio wave sensor. Also, as will be described in detail later, variations in reception sensitivity of radio wave sensors are also canceled out in the above calculation formula. Therefore, when installing an intensity sensor, it is necessary to consider variations in reception sensitivity of radio wave sensors. Disappears. As a result, the restriction on the arrangement position of the radio wave sensor is reduced, and the degree of freedom in design can be improved.

  For example, as shown in FIG. 3A, when the radio wave output of the front wheel tire sensor S1 is 50 dB and the radio wave output of the rear wheel tire sensor S2 is 50 dB, the signal from the tire sensor S1 in the radio wave sensor D1 The radio wave intensity value Rlf is 30 dB, the radio wave intensity value R1r of the signal from the tire sensor S1 at the radio wave sensor D2 is 28 dB, the radio wave intensity value R2f of the signal from the tire sensor S1 at the radio wave sensor D1 is 26 dB, and the radio wave sensor D2 It is assumed that two radio wave sensors D1 and D2 are installed at a position where the radio wave intensity value R2r of the signal from the tire sensor S2 is 31 dB. Then, when the above equation (1) is calculated, (R1f + R2r) = 61 dB> (R2f + R1r) = 54 dB, and when there is no variation in the radio wave outputs of the radio wave sensors D1, D2, it is natural that the tire position is recognized. You can see that it is done correctly.

  Here, when the radio wave outputs of the tire sensors S1 and S2 vary, for example, when the radio wave output of the front tire sensor S1 is 47 dB and the radio wave output of the rear tire sensor S2 is 52 dB due to manufacturing variations. When there is the same radio wave attenuation as in FIG. 3A, the radio wave intensity values are R1f = 27 dB, Rlr = 25 dB, R2f = 28 dB, and R2r = 33 dB. If the tire position is recognized only by the radio wave sensor D1, the radio wave intensity value R2f from the tire sensor S2 becomes larger than the radio wave intensity value R1f from the tire sensor S1, and each tire sensor is simply set. It can be seen that the tire position cannot be recognized correctly only by comparing the magnitude of the radio field intensity of the signal from.

  Therefore, when the present invention is applied to the situation as shown in FIG. 3B and the above equation (1) is calculated, (Rlf + R2r) = 60 dB> (R2f + R1r) = 53 dB, and the tire sensor S1 The difference between the left side and the right side is constant at 7 dB, the same as in the case of FIG. That is, in the present invention, it can be seen that the front and rear positions of the tire are correctly recognized without being affected by variations in the radio wave output of the tire sensors S1 and S2.

  Moreover, in the conventional tire pressure monitoring system, as a method for identifying the front and rear wheels, a tire sensor having a stronger signal received by a certain radio wave sensor is used for a wheel closer to the radio wave sensor. And a method of using two radio sensors, receiving signals from tire sensors with two radio sensors, and determining a radio sensor with a strong signal as a position closer to the tire sensor. ing. Considering that these systems are applied to the situation shown in FIG. 3B, the former determination method is such that the relationship between the radio wave intensity values is R1f <R2f, Rlr <R2r, and so on. The radio wave sensor strongly receives the signal from the tire sensor S2, and cannot correctly determine the front and rear positions of the tire. On the other hand, in the latter determination method, the relationship between the radio field intensity values becomes R1f> R1r, R2f <R2r, and the front and rear positions of the tire can be correctly determined. However, even if the latter determination method is used, if the reception sensitivity of the radio wave sensors D1 and D2 varies, the front and rear positions of the tire may not be correctly determined.

  When the reception sensitivity of the radio wave sensors D1 and D2 varies in addition to the fluctuation of the radio wave output of the tire sensors S1 and S2, for example, as shown in FIG. 3C, the radio wave sensor D1 is determined from the reception sensitivity of the radio wave sensor D2. When the reception sensitivity is 3 dB lower, the radio field intensity values are Rlf = 27-3 = 24 dB, Rlr = 25 dB, R2f = 28-3 = 25 dB, and R2r = 33 dB. In this case, the relationship between the radio wave intensity values is Rlf <R1r, R2f <R2r, and both the tire sensors S1 and S2 cannot determine the front and rear positions of the tire correctly because the radio wave intensity at the rear radio wave sensor D2 is large. . As described above, the latter determination method described above cannot correctly determine the front and rear positions of the tire when the reception sensitivity of the radio wave sensor varies.

  Therefore, when the present invention is applied to the situation as shown in FIG. 3C and the above formula (1) is calculated, (R1f + R2r) = 57 dB> (R2f + Rlr) = 50 dB, and the tire sensor S1 The difference between the left side and the right side is constant at 7 dB, which is the same as in FIGS. 3A and 3B, regardless of variations in the radio wave output of S2, and variations in the reception sensitivity of the radio wave sensors D1 and D2. That is, in the present invention, it is understood that the front and rear positions of the tire are correctly recognized without being affected by variations in radio wave output of the tire sensor and variations in reception sensitivity of the radio wave sensor.

  Conventionally, when deciding the installation position of a radio sensor, it is necessary to take into account variations in the radio output of the tire sensor, variations in the reception sensitivity of the radio sensor, variations in radio attenuation between the tire sensor and the radio sensor, and so on. However, according to the present invention, it is necessary to take into account variations in the radio output of the tire sensor, variations in the reception sensitivity of the radio sensor, and the like. Therefore, the degree of freedom in designing the installation location of the radio wave sensor can be increased. Here, in order to simplify the description, two of the four wheels have been taken up and described, but this is the same even when the position of the four wheels is recognized.

  FIG. 4 is a schematic configuration diagram showing another example of the embodiment of the tire pressure monitoring system according to the present invention. In FIG. 4, the same components as those shown in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 4, the tire pressure monitoring system of the present embodiment also includes tire sensors S1 and S2 installed in the front wheels T1 and rear wheels T2, and at least two radio wave sensors D1 and D2 installed in the vehicle 10. It is the structure which has.

In the present embodiment, the tire sensors S1 and S2 have not only a tire sensor that detects tire air pressure but also a tire rotation direction sensor that detects the tire rotation direction. Accordingly, the tire sensors S1 and S2 transmit the rotational direction information together with the air pressure value and the ID number, and the control device 1 determines the left and right wheels from the rotational direction information from the tire sensors S1 and S2 and the traveling direction information of the vehicle 10. Recognize For example, as shown in FIG. 4, when the vehicle 10 is moving forward, the front and tire sensors S1 _L of the left wheel T1 _L, the direction of rotation of the tire sensors S1 _R of the front right wheel T1 _R different (clockwise Therefore, it is possible to recognize whether the front wheel is the front left wheel T1 _L or the front right wheel T1 _R from the rotation direction information from the tire sensors S1 _L and S1 _R. Similarly, the left rear wheel T2 _L tire sensor S2 of _L, also different for the rotating direction of the tire sensor S2 _R of the rear right wheel T2 _R, the rotation direction information from the tire sensor S2 _L, S2 _R, left rear wheel T2 _L Or the rear right wheel T2 _R. That is, it becomes possible to recognize the front and rear wheels of the vehicle 10 by calculating the radio field strengths of the plurality of radio wave sensors D1 and D2, and the vehicle is determined based on the rotation direction information transmitted from the tire sensors S1 _L , S1 _R , S2 _L , S2 _R. Ten left wheels and right wheels can be recognized.

  Also in this embodiment, if the configuration includes a plurality of radio wave sensors at different positions in the front-rear direction of the vehicle, the configurations of the control device and the radio wave sensor are the configurations shown in FIGS. Anything is applicable, including

  That is, one radio wave sensor D1 is disposed on the front wheel T1 side (relative to the vehicle front side), and the other radio wave sensor D2 is disposed on the rear wheel T2 side (relative to the vehicle rear side). The radio wave intensity value detected at D2 is transmitted to the control device 1 and a predetermined calculation process is performed, so that the front and rear wheels can be reliably recognized. Then, the calculation unit 6 recognizes the front and rear, left and right mounted tire positions from the comparison of the radio wave intensity values of the signals from the tire sensors S1 and S2 in the radio wave sensors D1 and D2 and the rotation direction information, and receives the received air pressure. When the value is lower than a predetermined value, the warning light 7 installed in the instrument panel is turned on to perform calculation processing for warning the driver of the corresponding tire.

  Next, the details of the predetermined calculation process of the present embodiment performed by the calculation unit 6 of the control device 1, that is, the tire position recognition procedure will be described with reference to the flowchart of FIG.

<Step S10>
The tire position recognition procedure starts when the ignition (IG) is turned on.

<Step S11>
It is determined whether the signal of the ID number registered in the own vehicle has been received. If the signal is the ID number registered in the own vehicle, the process proceeds to step S12. Otherwise, the process returns to step S10. This has the purpose of eliminating signals from tire sensors of other vehicles.

<Step S12>
It is determined whether or not the air pressure value included in the received signal is equal to or lower than the warning threshold value. If the air pressure value is equal to or lower than the warning threshold value, an air pressure warning is issued (step S13), and the process proceeds to step S14. Proceed to step S14.

<Step S13>
From the storage of the arrangement positions of the tire sensors S1, S2 with respect to the tire position (see steps S18, S19 described later), the warning light 7 on the instrument panel is lit on the tire at the corresponding position to display the air pressure warning. At this time, if the set air pressure is different between the front wheel T1 and the rear wheel T2, it is recognized from the storage of the arrangement positions of the tire sensors S1, S2 with respect to the tire position whether the warning object is the front wheel T1 or the rear wheel T2. If it is the front wheel T1, it is compared with the set air pressure value of the front wheel T1 that should be warned, and if it is the rear wheel T2, it is compared with the set air pressure value of the rear wheel that should be warned. ing.

<Step S14>
The left and right wheel information is confirmed based on the rotation direction information included in the status signal. If the left wheel, the process proceeds to step S15, and the processes from steps S15 to S19 are performed. If it is the right wheel, the process proceeds to step S20. This is for the tire sensor determined to rotate in the same direction, that is, for the left wheel side, the following steps S15 to S19 are performed, and for the right wheel side, the following step S20 is performed. is there. Note that in step S20, processing exactly the same as that in steps S15 to S19 is performed, and thus detailed description thereof is omitted in FIG.

<Step S15>
Radio wave intensity values R1f, R1r, R2f, and R2r are stored for the received tire ID numbers, and the process proceeds to step S16. Here, R1f is a radio wave intensity value at the radio sensor D1 on the front side of the signal from the tire sensor S1, and R1r is a radio wave intensity value at the radio sensor D2 on the rear side of the signal from the tire sensor S1. . R2f is a radio wave intensity value at the front radio sensor D1 of the signal from the tire sensor S2, and R2r is a radio wave intensity value at the radio wave sensor D2 at the rear side of the signal from the tire sensor S2.

<Step S16>
The procedure steps S10 to S15 are repeated until the radio field intensity values from both the tire sensor S1 and the tire sensor S2 are stored.

<Step S17>
The equation (1) shown in the first embodiment is calculated, and if the equation (1) is satisfied, the process proceeds to step S18. If the equation (1) is not satisfied, the process proceeds to step S19.

  That is, in step S17, for the tire sensor determined to rotate in the same direction, the radio wave intensity from any one tire sensor detected by the radio wave sensor D1 and the rotation in the same direction detected by the radio wave sensor D2 For each combination with the radio field intensity from one tire sensor, the sum for each combination is obtained and the sum of each combination is compared. As a result of this comparison, as shown in steps S18 and S19 described later, the tire The front-rear position of each tire corresponding to the sensors S1, S2 is specified.

<Step S18>
The tire sensor S1 is determined to be the front wheel T1 side, and the tire sensor S2 is determined to be the rear wheel T2 side, stored, and the process returns to step S10.

<Step S19>
The tire sensor S2 is determined to be the front wheel T1 side, and the tire sensor S1 is determined to be the rear wheel T2 side, stored, and the process returns to step S10.

  That is, in summary, in this embodiment, as a method for determining the mounted tire position, the left and right wheels are determined using the rotation direction information from the tire sensors S1 and S2, and the two radio wave sensors D1 and D2 are used. The front and rear wheels are also determined by comparing the sum (R1f + R2r) and (R1r + R2f) of the radio wave intensity at each of the radio wave sensors D1 and D2.

  6 and 7 are diagrams showing another example of the embodiment of the tire pressure monitoring system according to the present invention, FIG. 6 is a flowchart for explaining the procedure of the arithmetic processing of this example, and FIG. It is a figure which shows the combination pattern of the tire position assumed in the arithmetic processing of a present Example.

  In this embodiment, in the configuration shown in the first embodiment, the calculation process performed by the calculation unit 6 of the control device 1 is performed by a method that is an extension of the first embodiment, thereby determining the front and rear wheels. Specifically, the first embodiment focuses on only the two front and rear wheels, calculates the radio field intensity of only the two front and rear wheels, and determines the front and rear wheels. All radio field intensities are calculated to determine front and rear wheels. In the present embodiment, the same components as those shown in the first embodiment will be described using the same reference numerals. However, for tires and tire sensors, unique identification signals (ID numbers: 1 to 4) are used. ), Specifically, tire sensor having ID = 1 is S1, tire is T1, tire sensor having ID = 2 is S2, tire is T2, tire sensor having ID = 3 S3, the tire is T3, the tire sensor having ID = 4 is S4, and the tire is T4.

  The details of the predetermined calculation processing of the present embodiment performed by the calculation unit 6 of the control device 1, that is, the tire position recognition procedure will be described with reference to the flowchart of FIG.

<Step S21>
The tire position recognition procedure starts when the ignition (IG) is turned on.

<Step S22>
It is determined whether the signal of the ID number registered in the own vehicle has been received. If the signal is the ID number registered in the own vehicle, the process proceeds to step S23, and if not, the process returns to step S21. This has the purpose of eliminating signals from tire sensors of other vehicles.

<Step S3>
It is determined whether or not the air pressure value included in the received signal is equal to or lower than the warning threshold value. If the air pressure value is equal to or lower than the warning threshold value, an air pressure warning is issued (step S24), and the process proceeds to step S25. Proceed to step S25.

<Step S24>
From the storage of the arrangement positions of the tire sensors S1 to S4 with respect to the tire position (see step S28 described later), the warning light 7 on the instrument panel is turned on for the tire at the corresponding position to display the air pressure warning. At this time, if the set air pressure is different between the front wheel and the rear wheel, it is recognized from the memory of the arrangement positions of the tire sensors S1 to S4 with respect to the tire position whether the warning target is the front wheel or the rear wheel. If it is the front wheel, it is compared with the set air pressure value of the front wheel that should be warned, and if it is the rear wheel, it is compared with the set air pressure value of the rear wheel that should be warned.

<Step S25>
For the received tire ID numbers 1 to 4, the radio wave intensity values R1f, R1r, R2f, R2r, R3f, R3r, R4f, R4r are stored, and the process proceeds to step S26.
Here, R1f is a radio field intensity value at the front side radio wave sensor D1 of the signal from the tire sensor S1, and R1r is a radio field intensity value at the rear side radio wave sensor D2 of the signal from the tire sensor S1. , R2f is a radio wave intensity value at the front side radio wave sensor D1 of the signal from the tire sensor S2, and R2r is a radio wave intensity value at the radio wave sensor D2 at the rear side of the signal from the tire sensor S2, and R3f Is the radio field intensity value at the radio sensor D1 on the front side of the signal from the tire sensor S3, R3r is the radio field intensity value at the radio sensor D2 on the rear side of the signal from the tire sensor S3, and R4f is The signal from the tire sensor S4 is a radio wave intensity value at the front side radio wave sensor D1, and R4r is a radio wave intensity value at the radio wave sensor D2 at the rear side of the signal from the tire sensor S4.

<Step S26>
The procedure steps S21 to S25 are repeated until the radio field intensity values from all of the tire sensor S1, the tire sensor S2, the tire sensor S3, and the tire sensor S4 are stored.

<Step S27>
The following formulas (2) to (7) are calculated from the stored radio wave intensity values, the maximum combination is obtained from the calculation results of formulas (2) to (7), and the process proceeds to step S28.
[R1f + R2f + R3r + R4r] (2)
[R1f + R3f + R2r + R4r] (3)
[R1f + R4f + R2r + R3r] (4)
[R2f + R3f + R1r + R4r] (5)
[R2f + R4f + R1r + R3r] (6)
[R3f + R4f + R1r + R2r] (7)

  That is, in step S27, out of the radio wave intensities of the tire sensors S1 to S4 detected by the radio wave sensor D1, the radio wave intensities of arbitrary two tire sensors and the radio wave intensities from the tire sensors S1 to S4 detected by the radio wave sensor D2. Among these, for the combination with the radio field intensity from the other two tire sensors different from the arbitrary two tire sensors described above, the sum for each combination is obtained and the combination that maximizes the sum is obtained. Among the combinations, the two tire sensors having the radio wave intensity at the radio wave sensor D1 are arranged on the radio wave sensor D1 side, and the other two tire sensors having the radio wave intensity at the radio wave sensor D2 are arranged on the radio wave sensor D2 side. Thus, as shown in step S28 described later, the front and rear of each tire corresponding to the tire sensors S1 to S4 It has identified the location.

  Here, with reference to FIG. 7, a combination pattern of tire positions (tire sensor positions) assumed in the arithmetic processing of this embodiment will be described.

  For example, when the above formula (2) is the maximum value, as shown in FIG. 7A, the tire position (tire sensor position) is T1 (S1), T2 (S2) on the front wheel side, and T3 (T3 ( S3) and T4 (S4) are combined. In the combination pattern shown in FIG. 7, the positions of the left wheel and the right wheel are unquestioned and may be reversed, including the following FIGS. 7 (b) to (f).

  Similarly, when the above expression (3) is the maximum value, as shown in FIG. 7B, the tire position (tire sensor position) is T1 (S1), T3 (S3) on the front wheel side, and T2 on the rear wheel side. When the combination pattern of (S2) and T4 (S4) is obtained and the above expression (4) is the maximum value, the tire position (tire sensor position) is T1 (S1) on the front wheel side as shown in FIG. , T4 (S4), the rear wheel side is a combination pattern of T3 (S3), T2 (S2), and the above formula (5) is the maximum value, the tire position (tire sensor position) is shown in FIG. As shown, when the front wheel side is a combination pattern of T2 (S2), T3 (S3), the rear wheel side is T1 (S1), T4 (S4), and the above formula (6) is the maximum value, the tire position (tire sensor) Position), as shown in FIG. Is a combination pattern of T2 (S2), T4 (S4), the rear wheel side is T1 (S1), T3 (S3), and the above formula (7) is the maximum value, the tire position (tire sensor position) is As shown in FIG. 7 (f), the front wheel side is a combination pattern of T3 (S3) and T4 (S4), and the rear wheel side is a combination pattern of T1 (S1) and T2 (S2).

<Step S28>
From the maximum combination [R _n1 f + R _n2 f + R _n3 r + R _n4 r] obtained in step S27, the n1 and n2 tire sensors are determined as the front wheel side, and the n3 and n4 tire sensors are determined as the rear wheel side and stored. Then, the process returns to step S1.

That, in summary, in the present embodiment, as the determination method of mounting a tire position, using two radio wave sensor D1, D2, the sum of the maximum field intensity at each wave sensors _{D1, D2 [R n1 f +} R n2 f + R n3 r + R n4 r] is determined to determine the front and rear wheels.

  Also in this embodiment, as shown in FIG. 4, if the tire sensors S1, S2, S3, and S4 have a tire rotation direction sensor, the left wheel right of the vehicle 10 is determined based on the transmitted rotation direction information. Circles can also be recognized.

  The present invention is applied to a tire pressure monitoring system that monitors the tire pressure of a vehicle, and monitors an object by wireless transmission / reception, such as output intensity and reception sensitivity of a plurality of transceivers used. As long as there is a possibility that correct measurement and control cannot be performed due to variations in the above, it can be applied to any device.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows the embodiment example of the tire pressure monitoring system which concerns on this invention, (a) shows arrangement | positioning of a radio wave sensor and a tire sensor, (b), (c) is a control apparatus, The structural example of a radio wave sensor is shown. 3 is a flowchart illustrating a tire position recognition procedure according to the first embodiment. It is a figure explaining the effectiveness of the present invention by comparison with a conventional example. It is a schematic block diagram which shows another example of embodiment of the tire pressure monitoring system which concerns on this invention, and is a figure which shows the advancing direction of a vehicle, and the rotation direction of a tire sensor. 6 is a flowchart illustrating a tire position recognition procedure according to a second embodiment. 6 is a flowchart illustrating a tire position recognition procedure according to a third embodiment. It is a figure which shows the combination pattern of the tire position assumed in the arithmetic processing of Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus 3, 8 Antenna 5, 9 Detection part 6 Calculation part (signal processing means)
7 Warning light 10 Vehicle D1 Radio wave sensor (first receiving means)
D1 radio wave sensor (second receiving means)
S1, S2, S3, S4 Tire sensors (transmission means)
T1, T2, T3, T4 tires

Claims (4)

Transmitting means that is provided in each tire of the vehicle and transmits an identification signal that can individually identify each tire, and a state signal that indicates the state of each tire including air pressure;
A first receiving means provided in a vehicle for detecting a radio field intensity of a signal from the transmitting means;
The second receiving means, which is installed away from the first receiving means in the front-rear direction of the vehicle and detects the radio field intensity of the signal from the transmitting means;
The identification signal from the transmitting means received by the first receiving means or the second receiving means while receiving the radio wave intensity detected by the first receiving means and the radio wave intensity detected by the second receiving means. And signal processing means to which the status signal is input,
The signal processing means includes
Of the radio field intensity of each transmission means detected by the first reception means, the radio field intensity from any transmission means, and among the radio field strengths of each transmission means detected by the second reception means, the arbitrary transmission means For each combination with radio field strength from different transmission means, find the sum for each combination and compare the sum of each combination to identify the front and rear positions of each tire corresponding to each transmission means. A tire pressure monitoring system for monitoring the state of each tire based on the state signal for the identified tire. A transmission means provided on each tire of the vehicle, for transmitting an identification signal capable of individually identifying each tire, and a state signal indicating the state of each tire including air pressure and the rotation direction of the tire;
A first receiving means provided in a vehicle for detecting a radio field intensity of a signal from the transmitting means;
The second receiving means, which is installed away from the first receiving means in the front-rear direction of the vehicle and detects the radio field intensity of the signal from the transmitting means;
The identification signal from the transmitting means received by the first receiving means or the second receiving means while receiving the radio wave intensity detected by the first receiving means and the radio wave intensity detected by the second receiving means. And signal processing means to which the status signal is input,
The signal processing means includes
Based on the information on the rotation direction of the state signal, for the transmission means determined to rotate in the same direction,
The radio wave intensity from any one transmission means detected by the first reception means and the other one transmission means rotating in the same direction as the arbitrary one transmission means detected by the second reception means The sum of the radio field intensity is the sum of the radio field intensity from the other one transmission unit detected by the first reception unit and the radio field intensity from the arbitrary one transmission unit detected by the second reception unit. If it is larger, it is determined that the arbitrary one transmission means is arranged on the first reception means side, and the other one transmission means is arranged on the second reception means side, and each of the transmission means corresponding to each transmission means is determined. A tire air pressure monitoring system characterized by identifying front and rear positions of a tire and monitoring a state of each tire based on the state signal for the identified tire. Transmission means provided on each of the four tires provided on the front, rear, left and right sides of the vehicle, for transmitting an identification signal capable of individually identifying each tire, and a state signal indicating the state of each tire including air pressure,
A first receiving means provided in a vehicle for detecting a radio field intensity of a signal from the transmitting means;
The second receiving means, which is installed away from the first receiving means in the front-rear direction of the vehicle and detects the radio field intensity of the signal from the transmitting means;
The identification signal from the transmitting means received by the first receiving means or the second receiving means while receiving the radio wave intensity detected by the first receiving means and the radio wave intensity detected by the second receiving means. And signal processing means to which the status signal is input,
The signal processing means includes
Of the radio field intensity of each transmission means detected by the first reception means, among the radio field intensity from any two transmission means and the radio field intensity from each transmission means detected by the second reception means, the arbitrary For the combination with the radio field intensity from the other two transmission means different from the two transmission means, the sum for each combination is obtained and the combination that maximizes the sum is obtained. The two transmitting means having the radio wave intensity at the first receiving means are on the first receiving means side, and the other two transmitting means having the radio wave intensity at the second receiving means are the second receiving means. The tire pressure is characterized in that it is determined that the tire is disposed on the side, the front-rear position of each tire corresponding to each transmission means is specified, and the state of each tire is monitored by the state signal for the specified tire Surveillance system Beam. The tire pressure monitoring system according to claim 3,
The transmission means transmits information indicating the rotation direction of each tire as a status signal of each tire,
The tire pressure monitoring system, wherein the signal processing means identifies a left wheel and a right wheel of a tire based on traveling direction information indicating a traveling direction of a vehicle and information indicating a rotation direction of the state signal.

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