JP2010266314A - Tire-monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a communication failure due to crosstalks, in a tire monitoring system of a vehicle. <P>SOLUTION: When an initiator 11 transmits a request signal to a sensor unit 30 of a tire 2, a comparison signal is transmitted from an initiator 12, corresponding to the tire 3 at a different timing, such as, timing immediately after the request signal is transmitted so as to prevent crosstalks that cause the sensor unit 30 of the tire 3 at a near position to respond to the request signal. Each sensor unit 30 measures the first physical quantity, such as, receiving strength of the request signal correlated with a first distance from the initiator 11 to the sensor unit, and the second physical quantity, such as, receiving strength of the comparison signal correlated with a second distance from the initiator 12 to the sensor unit, compares the first and second physical quantities, and implements an operation corresponding to the request signal, if it is determined that the second distance is larger than the first distance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a system for monitoring tire pressure and the like of a four-wheeled vehicle.

2. Description of the Related Art Recently, there is a tire pressure monitoring system (hereinafter referred to as TPMS) as a system for monitoring the state of tires in vehicles such as four-wheeled vehicles. In addition to pressure, a system for monitoring temperature, strain, rotation speed, acceleration, etc. has been devised.
The TPMS is, for example, a vehicle body side controller (ECU) capable of transmitting a wireless signal via an initiator (a wireless communication terminal on the vehicle body side including at least a transmission antenna) provided for each tire of the vehicle. A sensor unit (TPS) is provided on each tire of the vehicle and capable of measuring the pressure of each tire and transmitting the measurement result as a radio signal. The vehicle body side controller responds from an initiator at a specific location at a predetermined timing. A request signal (request signal) is transmitted as an LF wave (LF = abbreviation for Low Frequency) to the tire sensor unit, and the sensor unit that receives the signal transmits an answer signal including the measurement result. The UHF wave (high frequency) is transmitted to the vehicle body side controller, and the vehicle body side controller receiving it transmits the front For example, the system reads the measurement result and executes control to output an alarm when the pressure is abnormal.

  A two-way communication method for each tire that provides an initiator for each tire, transmits a request signal separately for each tire, and separately receives a measurement result from the sensor unit of each tire as an answer signal to the request signal. If so, the vehicle side controller can determine which position of the tire measurement result.

  By the way, in the two-way communication method for each tire as described above, the request signal transmitted to the sensor unit of the specific tire is also received by the sensor unit of the other tire and the answer signal is also received from the sensor unit of the other tire. When crosstalk is transmitted, tire position identification as described above becomes impossible. In addition, a plurality of answer signals interfere with each other, which may cause a problem that the ECU cannot normally receive the answer signal from the target TPS. For this reason, the communication range of the request signal from the initiator should naturally be limited to only a narrow range near the corresponding specific tire, and the transmission output of the request signal is naturally limited.

However, on the other hand, the tire rotates as the vehicle travels, and the position of the receiving antenna of the sensor unit also rotates as the tire rotates. For this reason, the position and orientation of the receiving antenna of the sensor unit on the tire side always fluctuate, and depending on the rotational position of the tire, it becomes difficult to receive the request signal, and if the transmission output of the request signal is weak, the request signal is received. There is a risk that communication will be disabled.
Therefore, conventionally, as seen in Patent Document 1, it has been proposed to transmit an interfering wave from a corresponding initiator to other adjacent tires that may have crosstalk.

JP 2005-207223 A

  An object of the present invention is to provide a tire monitoring system for a vehicle, in which the above-described problem of communication failure due to crosstalk is solved.

The tire monitoring system according to the present application includes, in a vehicle to which a plurality of tires are mounted, an initiator provided at a position close to each tire, a vehicle body side controller capable of transmitting a radio signal via the initiator, and a wireless communication from the initiator. A sensor unit that receives the signal, measures the state of each tire provided on each tire, and transmits the measurement result to the vehicle body side controller as a radio signal, the vehicle body side controller via each corresponding initiator A tire monitoring system that transmits a request signal to each sensor unit of each tire, and each sensor unit performs an operation according to the request signal,
The vehicle body side controller has a function of transmitting the request signal from one of the initiators corresponding to one of the sensor units and transmitting a comparison signal from another initiator corresponding to the sensor unit of another tire at a different time. Have
Based on the received request signal and the comparison signal, the sensor unit transmits a first physical quantity correlated with a first distance from the initiator to which the request signal is transmitted to the sensor unit, and the comparison signal is transmitted. The second physical quantity correlated with the second distance from the detected initiator to the sensor unit is measured, and it is determined from the first physical quantity and the second physical quantity that the second distance is larger than the first distance. A function that executes an operation according to the request signal in a case, and does not execute an operation according to the request signal when it is not determined that the second distance is greater than the first distance. To do.

Here, the “request signal” does not necessarily include data requesting the operation of the sensor unit (for example, a response from the sensor unit), and is a signal that causes the sensor unit to perform an operation in response to this signal. I just need it. For example, a mode in which a wake-up signal (activation signal) that activates a sensor unit that is in a power saving mode and in a so-called standby state (sleep mode) to a normal operation mode may also serve as the request signal. .
Alternatively, the power may be transmitted to the sensor unit by “request signal” or “comparison signal”.
The “operation according to the request signal” includes, for example, an operation of returning an answer signal including the tire information, an operation of intermittently transmitting an answer signal including the information of the tire, and an operation of pausing the sensor unit. possible.
The “comparison signal” is, for example, a signal that can be received by the same receiving circuit as the request signal. For example, if the request signal is an LF wave, the comparison signal is an LF wave. The “comparison signal” may include a command for requesting the sensor unit to perform some operation of the sensor unit (that is, a signal having a function similar to that of the request signal), but may not be. The “comparison signal” may include only a meaningless dummy code, for example.
The “vehicle” includes a vehicle (for example, a small airplane) equivalent to a general vehicle in addition to a general vehicle such as a four-wheeled vehicle. For example, the present invention can be applied to small airplanes because there are tires for wearing. A two-wheeled vehicle may also be used.

In the tire monitoring system of the present application, when the request signal is transmitted from a corresponding initiator to a sensor unit (target sensor unit) of any tire that is a target of tire condition detection, a close position where crosstalk may occur Even if the request signal is received by the sensor unit (other sensor unit) of the other tire in the other sensor unit, the operation according to the request signal (for example, reply of the answer signal) is not executed, Only the target sensor unit performs an operation corresponding to the request signal (for example, returns an answer signal). For this reason, the problem of communication failure due to crosstalk is avoided.
This is because the target sensor unit has a position range in which the distance from the initiator to which the comparison signal is transmitted (second distance) is larger than the distance from the initiator to which the request signal is transmitted (first distance). is there. On the other hand, in the other sensor units, the distance (second distance) from the initiator to which the comparison signal is transmitted is smaller than the distance from the initiator to which the request signal is transmitted (first distance). Is in range. For this reason, the function of the sensor unit described above (based on the received request signal and the comparison signal, when it is determined that the second distance is greater than the first distance, the operation according to the request signal is performed, When it is not determined that the second distance is greater than the first distance, only the target sensor unit performs the operation according to the request signal by the function that does not execute the operation according to the request signal). This is because the unit does not execute an operation according to the request signal.
Therefore, the transmission / reception of the request signal and the answer signal is established without causing a crosstalk failure, and thus only the sensor unit of a specific tire located at one desired position performs an operation corresponding to the request signal (for example, an answer). A signal can be returned). As a result, tire information at each position (such as tire pressure or tire-specific ID information) can be grasped while identifying the tire position. A practically useful effect is obtained in that the state of which tire is mounted at a position (rotation state of the tire position) can be automatically grasped by the vehicle body side controller.

  In the tire monitoring system of the present application, transmission / reception of a request signal and an answer signal can be established without causing a failure due to crosstalk, and the above-described problem of communication failure due to crosstalk can be solved.

It is a figure which shows the structure of the vehicle body side controller (ECU) and initiator which comprise a tire monitoring system. It is a figure which shows the structure of the sensor unit (TPS) which comprises a tire monitoring system. It is a figure explaining arrangement | positioning of the initiator etc. of a tire monitoring system, (a) is the figure which looked at the tire, the tire house, etc. from the running direction, (b) is a top view of a vehicle. (A) shows the data structure of a request signal, (b) is a figure which shows the data structure of the signal for a comparison. 4 is a flowchart showing the operation of the vehicle body side controller, where (a) shows a case where a request signal is transmitted from the right wheel initiator and (b) shows a case where a request signal is transmitted from the left wheel initiator. It is a flowchart which shows operation | movement of a sensor unit, (a) shows operation | movement of the sensor unit for right wheels, (b) shows operation | movement of the sensor unit for left wheels. It is a timing chart which shows operation | movement of the whole system. It is a timing chart which shows operation (other examples) of the whole system. It is a timing chart which shows operation (other examples) of the whole system.

Embodiment 1 of the present invention will be described below with reference to the drawings.
The vehicle 1 of this example is a four-wheeled vehicle shown in FIG. 3B in this case, and the tire monitoring system of this example has initiators 11 to 15 (in FIG. 1, initiator 13 as shown in FIG. 1). To 15), a vehicle body side controller (ECU) 20, and a sensor unit (TPS) 30.

Here, the initiators 11 to 15 are located in the vicinity of the tires 2 to 6 (including the spare tire 6 for replacement) shown in FIG. 3B (the tire house of each tire or the trunk lower portion in which the spare tire 6 is accommodated). Etc.) and is a communication terminal for transmitting a request signal and a comparison signal (both LF waves, for example, 125 kHz) to the sensor units 30 of the tires 2 to 6 under the control of the vehicle body side controller 20, An amplifier circuit 41 and an LC resonance circuit 42 for transmitting LF waves are provided (shown in FIG. 1). Note that the LF wave is advantageous when the communication range is narrowly limited to, for example, about 1 m, for example, a communication method that uses a near-field electromagnetic field up to several kilometers ahead and a magnetic field generated near the antenna as a transmission medium, for example, A communication system (electromagnetic induction system) used in contact IC cards is possible. The LC resonance circuit 42 functions as an antenna for the communication method.
In addition, the initiators 11 to 15 are usually resin-molded and have a vertical and horizontal thickness of about 2 to 5 cm, respectively.

Here, the request signal and the comparison signal are digital wireless signals that are transmitted by, for example, ASK modulating a carrier wave with a baseband signal (a pulse train corresponding to digital data). FIG. 4A is a diagram illustrating a data configuration example in one frame of the request signal. FIG. 4B is a diagram illustrating a data configuration example in one frame of the comparison signal. In this case, the request signal is made up of each data of the start pulse, TPS ID and command 1. The comparison signal is composed of TPS ID and command 2 data. Here, each data of the start pulse, the TPS ID, and the command 1 is, for example, ASK data in which predetermined “1” and “0” are combined.
Of these, the start pulse constitutes a signal (start signal) for starting the sensor unit 30 from the sleep mode.
The TPS ID is data unique to each sensor unit 30 (that is, unique to each tire) for identifying the tire and the sensor unit 30 corresponding to each initiator 11 to 15. The ID of the TPS is recorded in a memory 38, which will be described later, of the sensor unit 30, and the ID data of the sensor unit 30 corresponding to each of the initiators 11-15 is stored in a memory 26, which will be described later, of the vehicle body side controller 20. It is recorded. When the tire position is changed by tire rotation or the like, it is necessary to change the TPS ID data for each of the initiators 11 to 15 stored in the memory 26 of the vehicle body side controller 20. When the vehicle body side controller 20 reads the ID data included in the answer signal, the vehicle body side controller 20 can automatically learn and update the data.

The request signal and the comparison signal do not necessarily include the TPS ID, and there may be an aspect in which the TPS ID is not included in the request signal or the comparison signal. The order in which the TPS IDs are transmitted may be after commands 1 and 2.
Command 1 is a code representing a request to the sensor unit 30 (TPS). For example, an operation for returning an answer signal including tire information may be requested, an operation for intermittently transmitting the answer signal may be requested, or an instruction for pausing the operation of the sensor unit 30 (in sleep mode). Instruction to be transferred). In this example, it is assumed that the command 1 requests an operation of returning an answer signal including tire information.
The command 2 may be the same code as the command 1 or may be a dummy code (= no special meaning) that simply compares the received strengths. In this example, the command 2 has the same content as the command 1 Code.

The vehicle body side controller 20 is a TPMS main controller provided in a predetermined control box in the vehicle body, and includes a control circuit 21 comprising a microcomputer (hereinafter referred to as a microcomputer), a UHF wave receiving circuit 22 and a receiving antenna 23, Constant voltage power is supplied to the interface circuit 24 for outputting data as a request signal or a comparison signal to the initiators 11 to 15, the interface circuit 25 for outputting a signal to the in-vehicle LAN, the memory 26, and the control circuit 21. A constant voltage circuit 27 is included.
The vehicle body side controller 20 periodically executes a tire monitoring operation (details will be described later) of each tire periodically, for example, and when there is a tire whose pressure is not within the proper range, for example, the vehicle interior LAN is connected via the interface circuit 25. A signal indicating that (a signal indicating the tire position and pressure abnormality) is output to the display device (not shown) which has received the signal from the in-vehicle LAN, and turns on a warning lamp to the driver. An alarm (sound / light / character display alarm) indicating the tire position and pressure abnormality is output.
Note that the control circuit 21 of the vehicle body side controller 20 is activated only when the tire monitoring operation is necessary (for example, when the engine is operating, for example), so that the power consumption is minimized. Yes.

Next, the sensor unit 30 is provided in each tire (for example, the position of a valve). The sensor unit 30 includes a control circuit 31 (for example, a microcomputer), a pressure sensor 32 that measures the pressure of each tire, and information such as pressure data measured by the sensor is transmitted as a radio signal (UHF wave). A circuit 33 and a transmission antenna 34, and an interface circuit 35 and an LC resonance circuit 36 for receiving the request signal and the comparison signal, an RSSI circuit 37, a memory 38, and a built-in battery 39 are provided.
Here, the control circuit 31 of the sensor unit 30 is normally in a sleep mode, which is a power saving mode, and appropriately switches from the sleep mode to a normal mode (a startup state other than the sleep mode). It has become. In this example, the sensor unit 30 is activated and switched from the sleep mode to the normal mode by the activation pulse included in the request signal transmitted by the initiators 11 to 15.
The RSSI circuit 37 is a circuit that measures the intensity of the signal (LF wave) received by the LC resonance circuit 36. The control circuit 31 reads the output of the RSSI circuit 37 and receives a request signal or comparison signal. The reception strength of the signal can be grasped.
The sensor unit 30 is usually resin-molded and has a thickness of about 1 to 3 cm.

Next, the arrangement of the initiators 11 to 15 and the sensor unit 30 will be described.
As shown in FIG. 3A, the sensor unit 30 is fixed to the wheel of each tire and rotates as the tire rotates.
On the other hand, the initiators 11 to 14 corresponding to the tires 2 to 5 excluding the spare tire 6 are fixedly attached to the tire house 7 of the vehicle by screws or the like as shown in FIG. Yes. That is, the initiators 11 to 14 are disposed in the vicinity of the upper part of each tire.

Next, a characteristic configuration of this system and its operation and effect will be described.
In this system, when the vehicle body side controller 20 transmits a request signal from a corresponding initiator (for example, the initiator 11 for the right front wheel) to the sensor unit 30 of any tire, there is a possibility that crosstalk may occur. A comparison signal of the same type as the request signal is transmitted at a different time (in this example, immediately after the request signal is transmitted) from another initiator corresponding to the tire sensor unit 30 (for example, the initiator 12 for the front left wheel). It has a function. Based on the received request signal and the comparison signal, the sensor unit 30 correlates with the first distance from the initiator to which the request signal is transmitted to the sensor unit (in this example, the received intensity of the request signal). And a second physical quantity (in this example, the reception intensity of the comparison signal) correlated with the second distance from the initiator to which the comparison signal is transmitted to the sensor unit, and the first physical quantity and the second physical quantity are measured. If it is determined by comparison that the second distance is greater than the first distance (in this example, the reception strength of the request signal is greater than the reception strength of the comparison signal), an operation corresponding to the request signal is performed. If the second distance is not determined to be greater than the first distance, a function that does not execute the operation according to the request signal is provided.

  With this configuration, the present system has the following operational effects. That is, when a request signal is transmitted from the corresponding initiator to the sensor unit 30 (for example, the sensor unit 30 of the right front wheel 2) of any tire that is the target of tire condition detection, the position is at a position where there is a risk of crosstalk. Even if the request signal is received by a sensor unit of a certain other tire (for example, the sensor unit 30 of the left front wheel 3), the operation corresponding to the request signal (for example, reply of an answer signal) is executed in the other sensor unit. Instead, only the target sensor unit performs an operation corresponding to the request signal (for example, returns an answer signal). For this reason, the problem of communication failure due to crosstalk is avoided.

This is because the target sensor unit has a position range in which the distance from the initiator to which the comparison signal is transmitted (second distance) is larger than the distance from the initiator to which the request signal is transmitted (first distance). is there. On the other hand, in the other sensor units, the distance (second distance) from the initiator to which the comparison signal is transmitted is smaller than the distance from the initiator to which the request signal is transmitted (first distance). Is in range. For this reason, the function corresponding to the request signal is executed when it is determined that the second distance is larger than the first distance based on the function of the sensor unit 30 described above (the received request signal and the comparison signal). When it is not determined that the second distance is greater than the first distance, only the target sensor unit performs the operation according to the request signal by the function that does not execute the operation according to the request signal. This is because the sensor unit does not execute an operation according to the request signal.
Therefore, the transmission / reception of the request signal and the answer signal is established without causing trouble due to crosstalk, and thus, only the sensor unit 30 of a specific tire located at one desired location can be made to respond to the request signal. As a result, tire information at each position (such as tire pressure or tire-specific ID information) can be grasped while identifying the tire position. A practically useful effect is obtained that the vehicle body-side controller 20 can also automatically grasp the situation (the tire position rotation state) of which tire is mounted at the position.

The details and operation of the characteristic configuration of this system will be specifically described below.
Now, for example, a request signal is transmitted from the right front wheel initiator 11 (hereinafter referred to as the right wheel initiator) to the sensor unit 30 (hereinafter referred to as the right wheel sensor) of the right front wheel (tire 2). The reception sensitivity of the sensor units 30 that are mass-produced varies. Further, the position of the sensor unit 30 varies as the tire rotates. Considering these points, it is necessary to set the request signal so that the request signal is transmitted at such an intensity that communication can be performed regardless of the position of the right wheel sensor when the tire 2 rotates. As a result, the start signal may reach the sensor unit 30 (hereinafter referred to as the left wheel sensor) of the left front wheel (tire 3) in a close position, so an answer signal is also transmitted from an undesired left wheel sensor. There is a risk that crosstalk will occur. In order to prevent this, the vehicle body side controller 20 is configured to transmit a comparison signal from the left front wheel initiator 12 (hereinafter referred to as the left wheel initiator) immediately after the transmission of the request signal is completed. The comparison signal is also transmitted at such an intensity that the left wheel sensor can surely receive it. For this reason, when the sensor unit 30 with good reception sensitivity is attached as the right wheel sensor, the right wheel sensor also receives the comparison signal.

Hereinafter, a case where a request signal is transmitted from the right wheel initiator and a comparison signal is transmitted from the left wheel initiator will be described. Depending on the difference in the reception sensitivity of each sensor unit 30, four events (1) to (4) are considered as follows.
(1) When the right wheel sensor and the left wheel sensor receive the request signal and the comparison signal In this case, the right wheel sensor is activated by the activation pulse in the request signal, and receives the subsequent command 1 and command 2. Then, the right wheel sensor obtains the value of the reception intensity of command 1 received from the RSSI circuit 37. Further, the reception intensity value of command 2 is obtained in the same manner. The reception intensity (first physical quantity) of command 1 is compared with the reception intensity (second physical quantity) of command 2, and when the reception intensity of command 1 is large, the second distance is greater than the first distance. Since it is determined, for example, an answer signal is transmitted as a UHF radio signal in response to the command 1. When the reception intensity of the command 2 is large, it is not determined that the second distance is larger than the first distance, and therefore the operation corresponding to the command 1 is not executed (for example, no answer signal is transmitted). The right wheel sensor in a position range that is much closer to the right wheel initiator than the left wheel initiator naturally has a higher reception intensity of the command 1, and therefore, for example, an answer signal is returned in response to the command 1. On the other hand, the left wheel sensor is also activated by the activation pulse, and receives subsequent command 1 and command 2. Then, as with the right wheel sensor, the received intensity of command 1 is compared with the received intensity of command 2. However, the left wheel sensor naturally has a higher received intensity of command 2, so the operation corresponding to command 1 is not executed. (For example, answer signal is not returned).

  FIG. 7 is a timing chart showing the operation in the case (1). In FIG. 7, LFI-1 indicates a right wheel initiator, LFI-2 indicates a left wheel initiator, TPS-1 indicates a right wheel sensor, TPS-2 indicates a left wheel sensor, W1 indicates a start pulse, C1 indicates command 1, C2 indicates command 2, R1 indicates an answer signal returned from the right wheel sensor in response to command 1, and R2 indicates an answer signal returned from the left wheel sensor in response to command 2. ing. In FIG. 7, a request signal is transmitted from the right wheel initiator to the right wheel sensor (when a comparison signal is transmitted from the left wheel initiator) is shown on the left side. In addition, a request signal is transmitted from the left wheel initiator to the left wheel sensor. The case of transmission (when a comparison signal is transmitted from the right wheel initiator) is shown on the right side. In either case, only the target sensor returns an answer signal in response to the request signal depending on the magnitude relationship between the reception intensity of the request signal and the comparison signal.

(2) When the right wheel sensor receives the request signal and the comparison signal, and the left wheel sensor receives only the comparison signal. In this case, the right wheel sensor is the same as the above (1). Returns an answer signal. If the left wheel sensor is in the sleep mode, the activation pulse included in the request signal cannot be received and the activation is not performed, so that the operation according to the command 1 (for example, reply of an answer signal) cannot be executed. If the left wheel sensor has already been activated, a comparison signal can be received (for example, when intermittent transmission is performed). However, also in this case, the reception intensity of the command 1 of the request signal is compared with the reception intensity of the command 2 of the comparison signal, and the reception intensity value of the command 1 does not exist or is zero. Since it is determined to be larger, the left wheel sensor does not execute an operation corresponding to the command 1 (for example, reply of an answer signal).

(3) When the right wheel sensor receives only the request signal and the left wheel sensor receives the request signal and the comparison signal In this case, the right wheel sensor is activated by the activation pulse and receives the command 1. However, since the command 2 has not been received, when the reception strength of the command 1 is compared with the reception strength of the command 2, it is determined that the reception strength of the command 1 is large. Send back. On the other hand, the left wheel sensor is also activated by the activation pulse, and receives subsequent command 1 and command 2. However, the received intensity of command 1 is compared with the received intensity of command 2, and the received intensity of command 2 is larger. Therefore, the operation of the left wheel sensor according to command 1 (for example, reply of an answer signal) Do not execute.

(4) When the right wheel sensor receives only the request signal and the left wheel sensor receives only the comparison signal In this case, the right wheel sensor is activated by the activation pulse and receives the command 1. However, since the command 2 has not been received, when the reception strength of the command 1 is compared with the reception strength of the command 2, it is determined that the reception strength of the command 1 is large. Send back. If the left wheel sensor is in the sleep state, the activation pulse included in the request signal cannot be received and the activation is not performed, so that the operation according to the command 1 (for example, reply of an answer signal) cannot be executed. If the left wheel sensor has already been activated, a comparison signal can be received. However, in this case, the reception strength of command 1 is compared with the reception strength of command 2, and it is determined that the reception strength of command 2 is greater because the value of the reception strength of command 1 does not exist or is zero. Again, the operation according to the command 1 (for example, reply of an answer signal) is not executed.

As described above, in any of the above-described events (1) to (4), only the target sensor (in this case, the right wheel sensor) executes an operation according to the request signal.
In the above (1) to (4), the command 1 and the command 2 may be the same code or different codes. For example, the meaning of the code of command 2 is set as a transmission stop command. In this way, the left wheel sensor does not transmit the answer signal even by the command 2 itself, and does not perform the transmission even by comparing the received intensities, so that the answer signal transmission can be more reliably prohibited.
In the above description, the request signal is transmitted from the right wheel initiator to the right wheel sensor (when the right wheel sensor is a target), but the request signal is transmitted from the left wheel initiator to the left wheel sensor (left wheel sensor). 7), the left and right relationship is simply reversed as shown on the right side of FIG. That is, when a request signal is transmitted from the left wheel initiator to the left wheel sensor, a comparison signal is transmitted from the right wheel sensor, and only the left wheel sensor responds to the request signal by comparing the received intensity of these signals. Does not respond to the request signal.

Next, a specific example of the operation procedure of the tire monitoring operation executed by the control circuit 21 of the vehicle body side controller 20 will be described with reference to the flowchart of FIG.
After being activated, the control circuit 21 of the vehicle body side controller 20 performs a tire monitoring operation on each tire, for example, periodically.
In this tire monitoring operation, first, it is determined whether or not it is a predetermined detection timing. This detection timing means the timing which should be confirmed by reading information such as the pressure of the tire to be detected. For example, when the information is sequentially checked, such as the left front tire 3, then the right front tire 2, then the left rear tire 5, then the right rear tire 4, and the spare tire 6, the order of the tires to be detected comes around. It is the timing.
And if it is a detection timing, the operation | movement which reads and confirms the pressure of a tire, etc. will be performed about the applicable tire, and if it is not a detection timing, operation | movement will be stopped until it becomes a detection timing. Hereinafter, the subsequent operation will be described with reference to FIG. 5A by taking as an example a case where the corresponding tire is the right front tire 2 and the detection timing thereof.

First, in step S1, a request signal including a command for requesting a response of an answer signal is transmitted from the right wheel initiator 11 corresponding to the right front tire 2 to be detected. Next, in step S2, a comparison signal is transmitted from the left wheel initiator 12.
Next, in step S3, it is determined whether a proper answer signal has been properly received during a predetermined reception waiting time. Specifically, for example, it is determined whether or not an answer signal including a code that coincides with a pre-stored ID code unique to the vehicle body is received via the reception antenna 23. If such a normal answer signal is received during a predetermined reception waiting time, the process proceeds to step S4, and when the above reception waiting time has passed without properly receiving the normal answer signal, for example, Returning to step S1 or outputting an alarm, the operation is terminated. In this example, it is assumed that the answer signal transmitted by the sensor unit 30 includes the ID code specific to the vehicle body in addition to the ID data specific to TPS (that is, ID data specific to the tire) described above.

  In step S4, the received answer signal is read, processing such as code collation and pressure value confirmation is executed for the right wheel, and the operation is terminated. The process performed here is as follows, for example. That is, the pressure measurement data included in the received answer signal is read to determine whether the measurement data is normal (for example, whether the pressure is in an appropriate range). If not normal, an abnormality notification process is performed for the right front tire 2. Note that the pressure determination here may also be executed as to whether or not the pressure is too high. Further, even when the pressure is in an appropriate range, it may be determined that the pressure is a drop (a state where tire pressure replenishment is preferable). In the abnormality notification process, an alarm (sound, light, or character display) indicating that the tire 2 to be detected has a pressure abnormality (or that the pressure is low as described above, or the pressure value itself). Execute control to output alarm. In step S4, the tire unique ID included in the received answer signal is read, and the tire unique ID is recognized as the right front tire 2. The process of recognizing as the right front tire 2 means that if the tire-specific ID previously stored as the right front tire 2 is different from the tire-specific ID included in the received answer signal, the tire-specific ID included in the received answer signal Is newly stored as the right front tire 2.

  FIG. 5B is a flowchart showing the operation when the target tire is the left front tire 3 and the detection timing thereof, but is the same as FIG. 5A except that the left and right are reversed. Therefore, the same steps are denoted by the same reference numerals and description thereof is omitted.

Next, a specific example of the operation procedure executed by the control circuit 31 of the sensor unit 30 will be described with reference to the flowchart of FIG. 6A shows the operation of the right wheel sensor, and FIG. 6B shows the operation of the left wheel sensor, the contents are the same, and the other sensor units 30 are also the same.
When each sensor unit 30 receives a signal (pre-demodulation) having a specified frequency or higher at a specified frequency corresponding to the start pulse, the sensor unit 30 shifts to a normal mode and executes a request signal receiving process including the start pulse (step S21). If the prescribed start pulse is not received in step S21, the sleep mode is maintained and a signal input again is waited.

When the request signal is received in step S21, the process proceeds to step S22, and the operation of receiving the comparison signal is executed. For example, by determining the data length of the request signal and the data length of the comparison signal, or the transmission time, the sensor unit 30 can determine how much of the received signal is the request signal and where is the comparison signal. It can be determined, or may be determined according to the meaning of the code.
After step S22, the process proceeds to step S23. In step S23, the reception strength of command 1 of the request signal received in step S21 is compared with the reception strength of command 2 of the comparison signal received in step S22, and whether or not the reception strength of command 1 is greater. To determine. If the determination result in step S23 is affirmative, the process proceeds to step S24 to execute an operation according to the request signal (in this case, reply of an answer signal), and then return to the sleep mode and wait for a signal input again. If the determination result in step S23 is negative, the operation corresponding to the request signal (in this case, reply of the answer signal) is not executed, and the process returns to the sleep mode and waits for signal input again. Note that, as the answer signal transmission operation in step S24, for example, an operation of transmitting an answer signal including the data of each ID described above and the latest information (tire pressure data, etc.) of the mounted tire a predetermined number of times is executed.

  According to the system of the present example described above, a request signal and an answer signal are transmitted and received between the sensor unit 30 of each tire and the vehicle body side controller 20 at a predetermined detection timing, and the vehicle body side controller 20 receives the answer signal. If the pressure measurement data contained in the received answer signal is abnormal, an alarm indicating that the tire to be detected is abnormal is output, and the basic function as a two-way communication type TPMS for each tire is output. Realized.

  Moreover, as described above, when a request signal is transmitted to any one of the sensor units 30, in order to prevent crosstalk in which the sensor units 30 of other tires in close positions respond to the request signal. In addition, a comparison signal is transmitted from the initiator corresponding to the other tire. Based on the received request signal and the comparison signal, each sensor unit 30 receives a first physical quantity (in this example, reception of the request signal) correlated with the first distance from the initiator to which the request signal is transmitted to the sensor unit. Intensity) and a second physical quantity (reception intensity of the comparison signal in this example) correlated with the second distance from the initiator to which the comparison signal is transmitted to the sensor unit, and the first physical quantity and the second physical quantity are measured. When it is determined from the physical quantity that the second distance is greater than the first distance, an operation according to the request signal is performed, and when it is not determined that the second distance is greater than the first distance, the request signal Does not perform the operation according to For this reason, there is a possibility that crosstalk may occur when a request signal is transmitted from the corresponding initiator to the sensor unit 30 (for example, the sensor unit 30 of the right front wheel) of any tire that is a target of tire condition detection. Even if the request signal is received by the tire sensor unit (for example, the sensor unit 30 for the left front wheel), the operation corresponding to the request signal (for example, reply of the answer signal) is not executed in the other sensor units. Only the target sensor unit performs an operation corresponding to the request signal (for example, returns an answer signal). Therefore, the problem of communication failure due to the crosstalk described above can be solved.

In addition, this invention is not restricted to the Example mentioned above, There can be various deformation | transformation and application.
For example, in the above-described embodiment, the aspect in which the comparison signal is transmitted after the request signal is transmitted is illustrated, but the present invention is not limited to this. For example, there may be a mode in which the comparison signal is transmitted first and then the request signal is transmitted. Further, the first physical quantity and the second physical quantity of the present invention are not limited to the reception intensity of the request signal or the comparison signal. The first physical quantity and the second physical quantity of the present invention may be, for example, the strength of the carrier wave of the request signal or the comparison signal.

Further, when comparing the reception strength of the data included in the request signal and the data included in the comparison signal, the reception strengths of data other than the command 1 and the command 2 may be compared. For example, as shown in FIG. 9, when the TPS ID is included in the request signal and the comparison signal, the reception strength of the ID included in the request signal is compared with the ID included in the comparison signal, and the ID of the request signal is received. An answer signal may be returned when the strength is high. In FIG. 9, I1 and I2 indicate the data of the ID.
Further, when the request signal includes the TPS ID, the sensor unit (TPS) that has received the request signal collates the ID included in the signal with the ID stored in the memory by the TPS itself. An answer signal may be transmitted only when it does.
Further, a code (dummy code) only for measuring the reception strength is added to the request signal, and the dummy signal is included in the comparison signal so that each TPS has a dummy code of the request signal and a dummy code of the comparison signal. The reception strength may be compared. Alternatively, as shown in FIG. 8, only the dummy code is included in the comparison signal, and each TPS may compare the reception intensity of the command 1 of the request signal and the dummy code of the comparison signal. In FIG. 8, D1 and D2 indicate the dummy codes.

  In addition, when the comparison signal includes a command, the sensor unit compares the first physical quantity (for example, the reception intensity of the request signal) and the second physical quantity (for example, the reception intensity of the comparison signal) to the second distance rather than the first distance. Is not determined to be greater (for example, when the reception intensity of the comparison signal is greater than the reception intensity of the request signal), the sensor unit does not respond to the command of the request signal, but the comparison signal It is good also as an aspect which responds to this command.

  When registering the TPS ID in the vehicle body side controller (ECU), the request signal may include the command 1 for requesting the TPS to return the ID of the TPS itself. In this case, when the TPS receives the command 1 and returns an answer signal (including the ID of the TPS) based on the result of the predetermined reception strength determination, the ECU receives the answer signal and enters the included ID. It memorize | stores for every tire position in memory in ECU. If such an operation is started from a specific tire and IDs are sequentially stored corresponding to the tire positions, it is automatically learned which tire has a built-in TPS at which position. it can. For example, by determining the ID included in the answer signal intermittently transmitted from the TPS, it is possible to indicate on the display device which position of the tire is abnormal.

The “tire information” of the present invention is not limited to tire pressure, and may be tire temperature, strain, rotational speed, acceleration, and the like.
In the above embodiment, an example of preventing communication failure due to crosstalk between tires arranged on the left and right of the front part of the vehicle body has been described. Any tire can be applied. For example, a communication failure due to crosstalk between tires arranged on the left and right of the rear part of the vehicle body can be prevented with the same configuration, or tires arranged on the left and right of the rear part of the vehicle body (for example, the tire 4 in FIG. 3B). Alternatively, communication failure due to crosstalk between the spare tire (for example, the spare tire 6 in FIG. 3B) can be prevented with the same configuration.

DESCRIPTION OF SYMBOLS 1 Vehicle 2-6 Tire 11-15 Initiator 20 Car body side controller (ECU)
30 Sensor unit (TPS)

Claims (1)

In a vehicle equipped with a plurality of tires, an initiator provided at a position close to each tire, a vehicle body side controller capable of transmitting a radio signal via the initiator, and a radio signal received from the initiator. And a sensor unit that measures the state of each tire and transmits the measurement result to the vehicle body side controller as a radio signal, the vehicle body side controller to each tire sensor unit via each corresponding initiator. A tire monitoring system that transmits a request signal and each sensor unit performs an operation according to the request signal,
The vehicle body side controller has a function of transmitting the request signal from one of the initiators corresponding to one of the sensor units and transmitting a comparison signal from another initiator corresponding to the sensor unit of another tire at a different time. Have
Based on the received request signal and the comparison signal, the sensor unit transmits a first physical quantity correlated with a first distance from the initiator to which the request signal is transmitted to the sensor unit, and the comparison signal is transmitted. The second physical quantity correlated with the second distance from the detected initiator to the sensor unit is measured, and it is determined from the first physical quantity and the second physical quantity that the second distance is larger than the first distance. A function that executes an operation according to the request signal in a case, and does not execute an operation according to the request signal when it is not determined that the second distance is greater than the first distance. Tire monitoring system.

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