JP2006327324A - Tire condition monitoring device - Google Patents

Abstract

When transmitting tire information when a tire abnormality is detected, a communication error due to radio wave interference can be avoided and transmitted reliably.
A tire abnormality is determined based on a tire air pressure Pt detected by an air pressure sensor 11 provided on a tire 32 (S3), and when the tire abnormality is determined, the tire abnormality is wirelessly transmitted to a vehicle body side transceiver 22. Set the strength of the output radio wave to “strong” (S5) to avoid communication errors due to radio wave interference.
[Selection] Figure 4

Description

  The present invention relates to a tire condition monitoring device that monitors a tire condition based on tire information from a tire condition detection unit provided on the tire.

  2. Description of the Related Art Conventionally, various tire condition monitoring devices have been proposed that detect physical quantities (air pressure, temperature, etc.) indicating tire information from each tire of a vehicle and monitor whether the pressure, temperature, etc. of each tire are normal.

  That is, the tire condition monitoring device includes tire condition detection means for detecting the condition of a tire mounted on an air injection valve of each tire, and tire information such as air pressure and temperature of each tire detected by each tire condition detection means. A transmitter for wireless transmission, a receiver for receiving a signal transmitted from the transmitter, and a microcomputer for monitoring a tire condition based on tire information received by the receiver are provided.

  When the microcomputer detects that there is an abnormality in the tire pressure, temperature, etc., it is displayed on the display device provided on the instrument panel etc. Alert the person.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2003-182328) and Patent Document 2 (Japanese Patent Laid-Open No. 2004-331209), the measurement time intervals of the air pressure and temperature detected by the tire information detection sensor are usually set. Is disclosed at a relatively long measurement time interval, and when an abnormality occurs in the air pressure or temperature in the tire, a technique for measuring at a short interval is disclosed.

According to the technology disclosed in each of the above-mentioned documents, not only can the abnormal state of the tire be reported in detail, but also the normal measurement time interval is set to be relatively long, thereby suppressing battery consumption. Is possible.
JP 2003-182328 A Japanese Patent Laid-Open No. 2004-331090

  However, in the techniques disclosed in the above-mentioned documents, the intensity of the radio wave output transmitted from the transmitter is always constant, so that radio waves in the same frequency band are output from radio wave interference sources such as radio towers. If the vehicle is traveling in that area, a communication error may occur due to radio wave interference.

  To cope with this, it is possible to reduce communication errors due to radio wave interference by setting the radio wave output intensity to be close to the maximum output allowed by the Radio Law and always outputting at this output intensity. It is not preferable because the exhaustion of the heat becomes intense.

  In view of the above circumstances, the present invention can reliably transmit tire information detected by a tire condition detection unit provided on a tire without causing a communication error, and suppress consumption of the battery on the tire side. An object of the present invention is to provide a tire condition monitoring device that can perform such a process.

  In order to achieve the above object, the present invention provides a tire condition detection unit that is provided in a tire and detects the condition of the tire, a tire abnormality determination unit that determines a tire abnormality based on the detected tire condition, and at least the above When the tire abnormality determination means determines that the tire is abnormal, the transmission means for wirelessly transmitting the tire abnormality as tire information, the transmission output setting means for variably setting the intensity of the output radio wave at the time of wireless transmission, and the transmission means In the tire condition monitoring device having a receiving means for receiving the tire information transmitted wirelessly, the transmission output setting means sets the intensity of the output radio wave at a normal time at least when the tire abnormality determining means detects a tire abnormality. It is characterized in that it is set to a value stronger than the intensity.

  According to the present invention, the intensity of the output radio wave when a tire abnormality is detected is set to a value stronger than the normal intensity, so that a communication error at the time of abnormality detection is avoided and tire information is reliably obtained. In addition to being able to transmit, the intensity of the output radio wave at normal time is relatively weakened, so that battery consumption is suppressed and the battery life can be extended.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 5 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of a tire condition monitoring device.

  Reference numeral 1 in FIG. 1 denotes a vehicle such as an automobile, and wheels 2 are arranged on the front, rear, left, and right sides of the vehicle 1, respectively. As shown in FIG. 3, each wheel 2 includes a tire wheel 31 and a tire 32, and an air valve 33 that injects air into the tire 32 from the outside is attached to the tire wheel 31.

  A tire condition detection unit 3 is incorporated in each wheel 2. As shown in FIG. 2, the tire condition detection unit 3 includes a tire condition detection unit 4, a tire side transmission / reception controller 5, and a tire side transceiver 6 as a transmission unit. 6a is connected.

  In addition, a transmission / reception antenna 22a of a vehicle body side transmitter / receiver 22, which will be described later, is arranged corresponding to the transmission / reception antenna 6a of the tire side transmitter / receiver 6, and both the transmitters / receivers 6, 22 are connected via both transmission / reception antennas 6a, 22a. Thus, information can be transmitted and received wirelessly.

  The tire condition detection means 4 is composed of sensors that detect the condition of the tire. In this embodiment, the pressure sensor 11 that detects the air pressure (tire pressure) P in the tire 32 and the temperature of the tire 32 itself (tire temperature). A temperature sensor 12 for detecting T; a deflection amount sensor 13 for detecting a deflection δ of a sidewall of the tire 32; a wheel speed sensor 14 for detecting a wheel speed S and a rotational acceleration Gr from a centrifugal force acting on the tire 32; The lateral acceleration sensor 15 that detects the lateral acceleration Gy of the tire 32 is used. As shown in FIG. 3, in this embodiment, the air pressure sensor 11, the wheel speed sensor 14, the lateral acceleration sensor 15, the tire side transmission / reception controller 5, and the tire side transceiver 6 are attached to the air valve 33, The temperature sensor 12 and the deflection amount sensor 13 are attached to the tire 32.

  On the other hand, a tire information detection unit 21 is provided on the vehicle body side of the vehicle 1. Connected to the input side of the tire information detection unit 21 are a vehicle body side transmitter / receiver 22 as receiving means having a transmitting / receiving antenna 22a and a known navigation system 23 as area information collecting means. Further, an indicator 24 such as a lamp and a monitor and an alarm device 25 such as a buzzer and a speaker are connected to the output side of the tire information detection unit 21.

  The tire side transmission / reception controller 5 and the vehicle body side tire information detection unit 21 of the tire condition detection unit 3 are mainly configured by a microcomputer including a CPU, a ROM, a RAM, and the like. Further, a battery 7 is provided in the tire condition detection unit 3, and a driving power is supplied from the battery 7 to the tire-side transceiver controller 5, the sensors 11 to 15, and the tire-side transceiver 6. In the memory (RAM) of the tire-side transmission / reception controller 5, an ID code for identifying the tire 32 to which the tire state detection unit 3 is attached is registered in advance.

  Parameters (tire pressure Pt, tire temperature T, deflection amount δ, wheel speed S, rotational acceleration Gr, lateral acceleration Gy) indicating tire states detected by the sensors 11 to 15 are read by the tire-side transmission / reception controller 5. The tire side transmission / reception controller 5 determines the presence or absence of tire abnormality based on the read parameter indicating the tire state. When an abnormality is detected, data indicating the abnormality and data indicating the tire state and an ID code are output to the tire-side transceiver 6 as tire information of the tire 32. If no abnormality is detected, data indicating the tire condition and an ID code are output to the tire-side transceiver 6 as tire information of the tire 32. The tire side transceiver 6 wirelessly transmits the input tire information to the vehicle body side transceiver 22 via the transmission / reception antenna 6a.

  The tire information received by the vehicle body side transmitter / receiver 22 is read by the tire information detection unit 21, and based on the ID code included in the tire information, the transmission data from which tire 32 is identified and read. When the tire information includes data indicating tire abnormality, the fact is displayed on the display unit 24 and the alarm unit 25 is driven to notify the driver of the tire abnormality.

  In this case, the output interval of the tire data transmitted from the tire condition detection unit 3 to the tire information detection unit 21 may vary depending on the driving condition of the vehicle, or may be output almost continuously regardless of the driving condition of the vehicle. Furthermore, the radio wave output at that time is also set to a different value in an environment where radio wave interference is likely to occur and an environment where radio wave interference is unlikely to occur.

  Hereinafter, tire information output processing executed by the tire-side transmission / reception controller 5 will be exemplified using the flowcharts shown in FIGS. 4 and 5.

  FIG. 4 shows a tire air pressure data output processing routine as an example of a processing routine for varying the output interval according to the driving state of the vehicle and varying the radio wave output according to the traveling environment. FIG. 5 shows a tire temperature data output processing routine as an example of a processing routine for making the output interval constant regardless of the driving state of the vehicle and changing the radio wave output according to the traveling environment. The tire air pressure Pt and the tire temperature T are physical quantities that are at least necessary for detecting the tire state, and these must be received accurately at all times without being affected by radio wave interference.

  In the tire pressure data output processing routine shown in FIG. 4, first, in step S1, it is determined whether the vehicle is traveling or stopped. For example, based on a signal from the wheel speed sensor 14, the traveling state of the vehicle 1 is determined as traveling when the centrifugal force generated by the rotation of the wheel 2 is detected, and stopped when the centrifugal force is not detected. Judged as medium. Alternatively, it may be determined whether the vehicle is traveling or stopped based on the state of the ignition switch. That is, a signal from a control unit mounted on the vehicle 1 is read, and when the ignition switch is OFF, it is determined that the vehicle is stopped, and when the ignition switch is ON, it is determined that the vehicle is traveling.

  And when it determines with driving | running | working, it progresses to step S2, and when it determines with stopping, it branches to step S7. First, processing during traveling will be described.

  When the process proceeds to step S2, the output interval of the tire pressure Pt is set to [/ min] once and the timer starts counting. And when 1 minute passes, it progresses to step S3. When it is determined that the vehicle is stopped during the time counting, the timer count is cleared and the process branches to step S7. This output interval is an example, and may be as short as once every 15 seconds or as long as once every 3 minutes.

  In step S3, the absolute value (| Pt−Po |) of the difference between the tire air pressure Pt detected by the air pressure sensor 11 and the preset reference air pressure Po of the tire 32 and the allowable pressure difference α are calculated. The tire abnormality is determined by comparison. If it is determined that | Pt−Po |> α is abnormal, the procedure jumps to step S5, and the intensity of the radio wave output is “strong”, that is, the abnormality of the tire air pressure Pt is reliably transmitted by the radio wave method. Proceeding to step S12 after setting the maximum allowable output, the tire side transceiver transmits the data indicating the abnormal air pressure, the data indicating the tire air pressure Pt, and the tire information having the ID code together with the signal indicating the strength of the radio wave output. 6 to exit from the routine. The allowable differential pressure value α indicates an allowable value ± α with respect to the reference air pressure Po, and is determined and set in advance through experiments.

  In this embodiment, the intensity of radio wave output can be variably set in three levels: “strong”, “medium”, and “weak”. As will be described later, during traveling, the radio wave output when a tire abnormality is detected is set to “strong”, and the radio wave output when normal is set to “medium”. On the other hand, when the vehicle is stopped, the radio wave output when tire abnormality is detected is set to “medium”, and the radio wave output when normal is set to “weak”. The tire information includes data on the deflection amount δ, the wheel speed S, the rotational acceleration Gr, and the lateral acceleration Gy in addition to the data indicating the tire air pressure Pt and the tire temperature T.

  If it is determined in step S3 that the air pressure of | Pt−Po | ≦ α is normal, the process branches to step S4 to check whether there is a radio wave interference source such as a radio tower around the vehicle 1. Whether there is a radio wave interference source is determined by examining the current position of the host vehicle 1 and collecting the surrounding area information based on the position information and area information obtained from the navigation system 23. If there is a radio wave interference source around the host vehicle 1, the process proceeds to step S5, the intensity of the radio wave output is set to “strong” in order to reliably transmit the tire information, and the process proceeds to step S12. Execute the process and exit the routine.

  If there is no radio wave interference source in the vicinity of the host vehicle 1, the process proceeds to step S6, and the intensity of the radio wave output is set to “medium”, which is the normal output value. That is, since the vehicle is running, a communication error is taken into consideration, and a value that is weaker than the maximum output allowed by the Radio Law and stronger than the minimum required strength is set.

  Then, it progresses to step S12, the process mentioned above is performed, and a routine is exited.

  If it is determined in step S1 that the vehicle is stopped and the process branches to step S7, the output interval of the tire air pressure Pt is set to [/ hour] once and the timer starts counting. When one hour has passed, the process proceeds to step S8. When it is determined that the vehicle is running during the time measurement, the timer count is cleared and the process returns to step S2. This output interval is an example, and may be as short as once every several tens of minutes or as long as once every 1.5 hours.

  In step S8, the absolute value (| Pt−Po |) of the difference between the tire air pressure Pt detected by the air pressure sensor 11 and the preset reference air pressure Po of the tire 32 and the allowable pressure difference α are obtained. The tire abnormality is determined by comparison in the same manner as in step S3.

  When it is determined that | Pt−Po |> α, the air pressure abnormality is permitted by the Radio Law to jump to Step S10 and set the radio wave output intensity to “strong”, that is, to reliably transmit the air pressure abnormality data. The maximum output is set near the maximum output, the process proceeds to step S12, the above-described processing is executed, and the routine is exited.

  If it is determined in step S8 that the tire pressure is normal with | Pt−Po | ≦ α, the process branches to step S9 to determine whether there is a radio wave interference source such as a radio tower around the vehicle 1. 23. If there is a radio wave interference source, the process proceeds to step S10, the radio wave output intensity is set to “strong” in order to reliably transmit tire information, and the process proceeds to step S12. The above-described processing is executed to exit the routine.

  If there is no radio wave interference source around the host vehicle 1, the process proceeds to step S <b> 11, and the radio wave output intensity is set to “weak”, which is a normal output value. That is, the consumption of the battery 7 is suppressed by setting the required minimum strength while the vehicle is stopped.

  Then, it progresses to step S12, the process mentioned above is performed, and a routine is exited.

  As a result, the tire information is transmitted from the tire-side transceiver 6 to the vehicle-body-side transmitter / receiver 22 every time [/ min] during traveling and every time [/ hour] during stopping. Transmitted with radio wave output.

  On the other hand, tire information received by the vehicle body side transceiver 22 is output to the tire information detection unit 21. Based on the input tire information, the tire information detection unit 21 identifies the tire 32 provided with the transmitting tire side transceiver 6 from the ID code, grasps the tire pressure Pt from the tire pressure data, and The tire temperature T is grasped from the temperature data.

  The tire pressure Pt and the tire temperature T are displayed on the display 24. In this case, if data indicating an abnormality in air pressure are simultaneously input, the fact is displayed on the display 24 and the alarm device 25 is driven to notify the driver of the tire abnormality.

  The tire condition parameters (tire pressure Pt, tire temperature T, deflection amount δ, wheel speed S, rotational acceleration Gr, lateral acceleration Gy) input to the tire information detection unit 21 are not shown in CAN communication or the like. To a control unit (not shown) that controls the entire vehicle 1.

  Thus, in this embodiment, the output interval of the tire information is set to be relatively short when the vehicle 1 is running and relatively long when the vehicle 1 is stopped, so that it is attached to each wheel 2 during running. The state of the tire 32 can be grasped one by one, and the tire state can be detected more accurately. In addition, when the vehicle is stopped, the output interval is long, so that the battery 7 is less consumed and a longer life can be realized.

  Furthermore, since the intensity of the radio wave output is set to a large value when a tire abnormality is detected, a communication error is unlikely to occur and reliable transmission is possible. Similarly, when there is a radio wave interference source such as a radio tower in the vicinity of the vehicle 1, the radio wave output intensity is set to a large value, so that it is difficult to be affected by radio wave interference and communication errors can be avoided. Can do.

  Furthermore, since the normal radio wave output while the vehicle is stopped is set to a small value, the power consumption of the tire-side transceiver 6 is reduced, and the consumption of the battery 7 can be further reduced.

  Next, tire information output processing including tire temperature data will be described in accordance with the tire temperature data output processing routine shown in FIG. In the tire pressure data output processing routine shown in FIG. 4 described above, the tire information output interval is set to a different time between running and stopped. In this embodiment, tire information is always output at a constant output interval (calculation cycle). Is output.

  In this routine, first, in step S21, the outside air temperature Tg and the tire air pressure Pt are read. As the outside air temperature Tg, for example, a value detected by an outside air temperature sensor (not shown) provided in the vehicle 1 is read.

  Next, the wheel speed S detected by the wheel speed sensor 14 is read in step S22, and the reference tire temperature Tx during traveling is set based on the outside air temperature Tg, the tire air pressure Pt, and the wheel speed S in step S23. The reference tire temperature Tx indicates a center value when the temperature of the tire 32 during running is in a normal range, and is set from a map search or the like based on the parameters Tg, Pt, and S.

  In step S24, the tire temperature T detected by the temperature sensor 12 is read. In step S25, the absolute value (| T−Tx |) of the difference between the tire temperature T and the reference tire temperature Tx and the allowable temperature difference β And when it is determined that | T−Tx |> β is a tire temperature abnormality, the process jumps to step S27 to set the radio wave output intensity to “strong”, that is, to reliably transmit the tire temperature abnormality. The value is set near the maximum output allowed by the method, and the process proceeds to step S29. In step S29, tire information including tire temperature abnormality data, tire temperature T data, and ID code is output to the tire-side transceiver 6 and the routine is exited. The allowable temperature difference β indicates an allowable value ± β with respect to the reference tire temperature Tx, and is set in advance by experiments.

  If it is determined in step S25 that the tire temperature is normal with | T−Tx | ≦ β, the process branches to step S26 to determine whether there is a radio wave interference source such as a radio tower around the vehicle 1. 23. If there is a radio wave interference source, the process proceeds to step S27, and the strength of the radio wave output is set to “strong” in order to avoid a communication error. Then, it progresses to step S29, the process mentioned above is performed, and a routine is exited.

  On the other hand, if there is no radio wave interference source around the host vehicle 1, the process proceeds to step S28, and the radio wave output intensity is set to "weak" which is an output value at the normal time. That is, since there are few obstacles that cause a communication error while the vehicle is stopped, the consumption of the battery 7 is suppressed by setting the required minimum strength.

  Then, it progresses to step S29, the process mentioned above is performed, and a routine is exited.

  Thus, even if tire information is output continuously every calculation cycle regardless of the running state of the vehicle 1, the strength of the radio wave output is in an area where the vehicle 1 is likely to generate radio wave interference. In this case, when a tire temperature abnormality is detected, a large value is set, so that the occurrence of a communication error is prevented and the tire information can be transmitted reliably.

  6 to 8 show a second embodiment of the present invention. 6 and 7 show a tire information output processing routine. Since the components of the tire condition monitoring device are the same as those in FIGS. 1 and 2, the same reference numerals as those in FIGS.

  In the first embodiment described above, tire information that is output at different output intervals during traveling and when the vehicle is stopped and tire information that is output at every calculation cycle regardless of the traveling state of the vehicle 1 are processed by different programs. In this embodiment, both the tire information is processed by one program.

  This routine is executed every predetermined calculation cycle. First, in step S31, it is determined whether the vehicle is running or stopped. The determination of the running state of the vehicle 1 is performed in the same process as step S1 shown in FIG.

  And when it determines with driving | running | working, it progresses to step S32, and when it determines with stopping, it branches to step S43. First, processing during traveling will be described.

  In step S32, the absolute value (| Pt−Po |) of the difference between the tire air pressure Pt detected by the air pressure sensor 11 and the preset reference air pressure Po of the tire 32 and the allowable pressure difference α are obtained. The tire abnormality is determined by comparison.

  If it is determined that | Pt−Po |> α is abnormal, the procedure jumps to step S39, where the intensity of the radio wave output is “strong”, that is, permitted by the radio wave law in order to reliably transmit the abnormal air pressure. The vicinity of the maximum output is set, the process proceeds to step S40, the output interval is set to “t1”, and the process proceeds to step S52. t1 is a short output interval time, and is set to about 10 to 20 seconds in this embodiment. Therefore, when an abnormality in air pressure is detected, data of the tire air pressure Pt that changes every moment can be transmitted from the tire-side transceiver 6 to the vehicle-body-side transceiver 22 one by one.

  If it is determined in step S32 that the air pressure of | Pt−Po | ≦ α is normal, the process branches to step S33, and in steps S33 to S37, it is checked whether or not the tire temperature T is abnormal. Steps S33 to S37 correspond to steps S21 to S25 of the tire temperature data output processing routine shown in FIG.

  That is, the outside air temperature Tg is read in step S33, and the wheel speed S is read in step S34. In step S21 described above, the tire air pressure Pt is read. In this routine, the tire air pressure Pt is already read in step S32. Therefore, in step S33, only the outside air temperature Tg may be read.

  In step S35, the reference tire temperature Tx is set based on the outside air temperature Tg, the tire air pressure Pt, and the wheel speed S, and the tire temperature T is read in step S36.

  In step S37, the absolute value (| T−Tx |) of the difference between the tire temperature T and the reference tire temperature Tx is compared with the allowable temperature difference β, and the tire temperature abnormality of | T−Tx |> β is determined. When it is determined, the process jumps to step S39 described above. When it is determined that | T−Tx | ≦ β is normal, the process proceeds to step S38.

  In step S38, whether or not there is a radio wave interference source such as a radio tower in the vicinity of the vehicle 1 is checked based on information obtained from the navigation system 23 as in step S26 of FIG. If there is, the process proceeds to step S39, the radio wave output is set to “strong” to avoid a communication error, and the process proceeds to step S40.

  If it is determined in step S38 that there is no radio wave interference source in the vicinity of the host vehicle 1, the process proceeds to step S41, and the intensity of the radio wave output is set to “medium” which is the normal output value. The communication error is avoided and the process proceeds to step S42.

  In step S42, the output interval is set to “t2”, and the process proceeds to step S52. t2 is an output interval time slightly longer than the output interval t1, and is set to about 30 to 60 seconds in this embodiment. Even if the tire pressure Pt and the tire temperature T are normal, it is not necessary to transmit the vehicle 1 at an interval as short as the output interval t1 because the vehicle 1 is running. Need to be sent to. By setting the normal output interval t2 longer than the abnormal output interval t1, consumption of the battery 7 can be suppressed.

  When the process proceeds from step S40 or step S42 to step S52, the deflection amount δ of the sidewall of the tire 32 detected by the deflection amount sensor 13 and the lateral acceleration Gy acting on the tire 32 detected by the lateral acceleration sensor 15 are read. Proceed to S53.

  In step S53, data indicating the amount of deflection δ and data indicating the lateral acceleration Gy, and data indicating abnormality in tire air pressure when an abnormality in tire air pressure Pt is detected in step S32, or abnormality in tire temperature T in step S37 are detected. In this case, tire temperature abnormality data and tire information including an ID code are output to the tire-side transceiver 6 and the routine is exited.

  Then, tire information is transmitted from the tire-side transmitter / receiver 6 to the vehicle-body-side transmitter / receiver 22 at a set output interval t1 or t2 with a radio wave output having an instructed intensity.

  On the other hand, tire information received by the vehicle body side transceiver 22 is output to the tire information detection unit 21. Based on the input tire information, the tire information detection unit 21 identifies the tire 32 provided with the transmitting tire side transceiver 6 from the ID code, grasps the tire pressure Pt from the tire pressure data, and bends. The amount of deflection δ of the tire 32 is grasped from the amount data, and the lateral acceleration Gy applied to the tire 32 is grasped from the lateral acceleration data.

  The tire pressure Pt is displayed on the display 24. In this case, if data indicating an abnormality in air pressure or data indicating an abnormality in tire temperature is input at the same time, a message to that effect is displayed on the display unit 24 and the alarm unit 25 is driven to cause the driver to Announce abnormality.

  The tire condition parameters (tire pressure Pt, tire temperature T, deflection amount δ, wheel speed S, rotational acceleration Gr, lateral acceleration Gy) input to the tire information detection unit 21 are not shown in CAN communication or the like. To a control unit (not shown) that controls the entire vehicle 1.

  Next, processing during stoppage will be described. When it is determined that the vehicle is stopped in step S31 and the process branches to step S43, the absolute value (| Pt−) of the difference between the tire air pressure Pt and the preset reference air pressure Po of the tire 32 is the same as in step S32 described above. Po |) and the allowable pressure difference α are compared to determine tire abnormality.

  If it is determined that | Pt−Po |> α is an air pressure abnormality, the process jumps to step S49 to increase the radio wave output intensity to “medium”, that is, to make the radio wave output “strong” because the vehicle is stationary. However, since an abnormality in air pressure is detected, a communication error is taken into consideration, and the medium power is set to a medium strength that is weaker than the maximum output allowed by the Radio Law and stronger than the minimum required strength, and goes to step S51. move on.

  If it is determined in step S43 that | Pt−Po | ≦ α is normal, the process branches to step S44, and the outside air temperature Tg is read. In step S45, the reference tire temperature Ty when the vehicle is stopped is changed to the outside air temperature Tg. The tire temperature Pt is set based on the tire pressure Pt, and the tire temperature T is read in step S46. The reference tire temperature Ty indicates a center value when the temperature of the tire 32 at the time of stopping is in a normal range, and is set from a map search or the like based on the parameters Tg and Pt.

  In step S47, the absolute value (| T−Ty |) of the difference between the tire temperature T and the reference tire temperature Ty is compared with the allowable temperature difference β, and the tire temperature abnormality of | T−Ty |> β is determined. When it is determined, the process jumps to step S49 described above. If it is determined that | T−Ty | ≦ β is normal, the process proceeds to step S48.

  In step S48, whether or not there is a radio wave interference source such as a radio tower in the vicinity of the vehicle 1 is examined based on information obtained from the navigation system 23 as in step S26 of FIG. If there is, the process proceeds to step S49, the radio wave output is set to “medium” to avoid a communication error, and the process proceeds to step S51.

  If it is determined in step S48 that there is no radio wave interference source around the host vehicle 1, the process proceeds to step S50 where the radio wave output intensity is set to “weak”, which is a normal output value, and step S51. Proceed to By setting the intensity of the radio wave output while the vehicle is stopped to “weak” when normal, it is possible to suppress the consumption of the battery 7.

  Then, when the process proceeds from step S49 or S50 to step S51, the output interval is set to “t3”, and the process proceeds to the above-described step S52. t3 is an output interval time longer than the output interval t2, and is set to about 30 minutes to 1 hour in this embodiment. For example, even when an abnormality occurs in the tire pressure Pt or the tire temperature T while the vehicle is stopped, there is almost no need to respond urgently. Therefore, even if the tire information output interval t3 is set to a relatively long interval time, inconvenience occurs. There is nothing. Further, by setting the output interval t3 when the vehicle is stopped to a relatively long interval time, the consumption of the battery 7 can be further suppressed.

  The output intervals t1, t2, and t3 described above can be arbitrarily set as long as they have a relationship of t1 <t2 <t3. Also, the intensity (strong, medium, weak) of the radio wave output can be arbitrarily set as long as it is within the range allowed by the Radio Law.

  In this way, in this embodiment, as shown in FIG. 8, the timing for outputting tire information is divided into running and stopped, and when the tire 32 is normal during running, the radio wave output is changed to radio wave interference. Is set to “medium” in consideration of the communication error due to the above, and the output interval is set to “t2” which is relatively long, so that the consumption of the battery 7 is suppressed. In addition, when a tire abnormality is detected, the radio wave output is set to “strong” and the output interval is set to a short “t1” to generate a communication error due to radio wave interference with tire information that changes every moment. It is possible to transmit one by one without making it.

  On the other hand, while the vehicle is stopped, when the tire 32 is normal, the radio wave output is set to “weak” and the output interval is set to “t3”, so that the consumption of the battery 7 is further suppressed. In addition, when a tire abnormality is detected, the radio wave output is set to “medium” without changing the output interval t3, so that transmission of tire information while the vehicle is stopped does not cause a communication error. Not only can it be transmitted reliably, but the consumption of the battery 7 can be further suppressed.

  In this embodiment, the tire air pressure Pt that has the most influence on the running performance of the vehicle 1 is preferentially checked, and when an abnormality is detected in the tire air pressure Pt, the tire temperature T is checked without checking whether the tire temperature T is normal. Since the abnormality data is output, when an abnormality occurs in the tire air pressure Pt, the driver can be notified of the abnormality instantly via the display 24 and the alarm device 25.

Whole structure figure of tire condition monitoring device by the 1st form Same configuration diagram of tire condition detection unit Schematic showing the mounting state of the tire condition detection unit A flowchart showing a tire pressure data output processing routine The flowchart showing the tire temperature data output processing routine Flowchart showing a tire information output processing routine according to the second embodiment (part 1) Flowchart showing the tire information output processing routine (No. 2) Timing chart showing tire information output timing and radio wave output intensity during traveling and stopping

Explanation of symbols

1 ... vehicle,
2 ... wheels,
3 ... tire condition detection unit,
4 ... Tire condition detection means,
5. Tire side transmission / reception controller,
6 ... Tire side transceiver
7 ... Battery,
11 ... Air pressure sensor,
12 ... temperature sensor,
13: Deflection sensor,
14: Wheel speed sensor,
15 ... Lateral acceleration sensor,
21 ... Tire information detection unit,
22 ... body side transceiver
24. Display,
25 ... alarm,
32 ... tyre,
α: Differential pressure tolerance,
β: Allowable temperature difference,
δ: Deflection amount,
Gr: Rotational acceleration,
Gy ... Lateral acceleration,
Po: Reference air pressure,
Pt ... tire pressure,
S ... wheel speed,
T ... Tire temperature
Tg: outside temperature,
Tx, Ty ... reference tire temperature,
t1, t2, t3 ... output interval,

Claims (5)

Tire condition detection means provided on the tire for detecting the condition of the tire;
Tire abnormality determination means for determining tire abnormality based on the detected tire condition;
When at least the tire abnormality determining means determines that the tire is abnormal, a transmitting means for wirelessly transmitting the tire abnormality as tire information;
Transmission output setting means for variably setting the intensity of the output radio wave at the time of wireless transmission;
In a tire condition monitoring device having receiving means for receiving the tire information wirelessly transmitted from the transmitting means,
The transmission output setting means sets the intensity of the output radio wave to a value stronger than the normal intensity at least when the tire abnormality determination means detects a tire abnormality. The tire condition monitoring apparatus according to claim 1, wherein the transmission means wirelessly transmits the tire condition detected by the tire condition detection means as the tire information. The transmission output setting means, when there is a radio wave interference source around the host vehicle, sets the intensity of the output radio wave to a normal intensity even when the tire abnormality determination means determines that the tire condition is normal. 3. The tire condition monitoring apparatus according to claim 1, wherein the tire condition monitoring apparatus is set to a stronger value. 4. The tire condition monitoring apparatus according to claim 3, wherein the radio wave interference source is examined based on position information of the own vehicle and area information obtained from area information collecting means. The transmission output setting means sets the output interval of the radio transmission shorter than the normal output interval when the intensity of the output radio wave is set to a value stronger than the normal intensity. Item 5. The tire condition monitoring device according to any one of Items 1 to 4.

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