JP2012096640A - Sensor unit registering system and sensor unit registering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor unit registering system capable of easily registering a sensor unit of a tire air pressure monitoring system to a vehicle.SOLUTION: Each sensor unit is attached to a location corresponding to each of the cutouts 43 formed at a disc on which each tire is fitted. The sensor unit transmits a radio signal including gravitational acceleration information corresponding to a rotation position of the tire in addition to identification information of its own and tire air pressure information. When a vehicle monitoring system detects one of the cutouts 43 and receives a radio signal including acceleration information corresponding to the position of each of the cutouts 43, the vehicle monitoring system registers identification information included in the radio signal as information associated with a fitting position of a tire corresponding to the detected one of cutouts 43.

Description

  The present invention relates to a system and method for registering a sensor unit of a tire pressure monitoring system.

  Conventionally, as described in Patent Document 1, for example, a tire pressure monitoring system for monitoring the tire pressure of a vehicle is known. The system includes a sensor unit with a wireless communication function provided in each tire of a vehicle. This sensor unit detects the air pressure of the tire and transmits a radio signal including the detected air pressure information and identification information unique to itself. This radio signal is received by a monitoring device provided in the main body of the vehicle. In the apparatus, the identification information of each sensor is registered in advance in a state in which it is associated with the mounting position (left front, left rear, right front, right rear) of each tire. Then, the device determines which of the tires the air pressure information included in the wireless signal is based on the identification information included in the received wireless signal, and determines the air pressure of each tire based on the air pressure information. Monitor for abnormalities. When it is determined that any one of the tires has an abnormal air pressure, the device warns that through a display device in the passenger compartment. The driver can recognize which of the tires is abnormal through the warning.

JP 2004-17909 A

  In the system of Patent Document 1, sensor unit identification information is registered in the monitoring device through a dedicated registration tool. That is, as shown in FIG. 9, after the registration tool 63 is connected to the monitoring device 61 and each sensor unit 62, the identification information is sequentially transmitted from the registration tool 63 to the monitoring device 61 and each sensor unit 62. The Identification information transmitted from the registration tool 63 is sequentially registered in the monitoring device 61 and each sensor unit 62.

  However, in the system of Patent Document 1, when registering the identification information of each sensor unit 62 in the monitoring device 61, it is necessary to connect a dedicated registration tool 63 to the monitoring device 61 and each sensor unit 62, respectively. It was very troublesome.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a sensor unit registration system and a sensor unit registration method capable of easily registering a sensor unit of a tire pressure monitoring system in a vehicle. There is to do.

  <1> According to the first aspect of the present invention, a sensor unit that is provided in each tire and transmits a wireless signal including the air pressure information and identification information unique to itself is used to monitor the air pressure of each tire based on these wireless signals. In each sensor unit registration system for registering in an in-vehicle device, each sensor unit corresponds to a mark provided so as to be visible from the outside with respect to an attachment target of each tire, and gravity acceleration information corresponding to the rotation position of each tire is provided. When the vehicle-mounted device detects any one of the marks and receives a radio signal including gravitational acceleration information corresponding to the one mark position, the radio signal is transmitted. The gist is to register the identification information included in the vehicle in association with the mounting position of the tire corresponding to the detected mark.

  According to this configuration, when exchanging the tire, the user only needs to attach the tire to the attachment target so that the mark provided on the tire attachment target matches the sensor unit. Thereafter, as the vehicle travels, the mounting position of the sensor unit is specified based on the presence / absence of mark detection and the acceleration information included in the wireless signal from the sensor unit. That is, when a radio signal including gravitational acceleration information corresponding to the mark position is received in a state where one mark is detected, the sensor unit that has transmitted the radio signal transmits a tire corresponding to the detected mark. It can be seen that it is provided. This is because the mark and the sensor unit are provided so as to correspond to each other, and thus the gravitational acceleration corresponding to the mark position acts on the sensor unit corresponding to the detected mark. Then, the identification information is registered in the in-vehicle device in association with the specified mounting position of the sensor unit. Thus, the user does not need to perform a special registration operation or the like, and can easily register the sensor unit in the vehicle.

  <2> The invention according to claim 2 is the sensor unit registration system according to claim 1, wherein when the in-vehicle device detects any one of the marks, the acceleration corresponding to the detection position of the mark is detected. The gist of the invention is that when a wireless signal including information is received, the identification information included therein is registered in association with the mounting position of the tire corresponding to the detected mark.

Under such conditions, the mounting position of the sensor unit can also be specified.
<3> The invention according to claim 3 is included in the sensor unit registration system according to claim 1, wherein the in-vehicle device receives a radio signal including acceleration information corresponding to a specific mark position. The gist is to register the identification information to be associated with the mounting position of the tire corresponding to the mark detected to be present at the specific position.

  When a radio signal including acceleration information corresponding to a specific mark position is received, it can be said that any mark is present at the specific position. Therefore, when a wireless signal including acceleration information corresponding to a specific mark position is received, the wireless signal is transmitted from the sensor unit corresponding to the mark detected to be present at the specific mark position. It is specified that there is. The identification information included in the received radio signal is registered in association with the mounting position of the tire corresponding to the mark detected to be present at the specific position. Thus, according to the present invention, identification information registration processing can be performed more quickly.

  <4> The invention according to claim 4 is the sensor unit registration system according to any one of claims 1 to 3, wherein the sensor unit spontaneously transmits the wireless signal. The gist.

  According to the present invention, since each sensor unit spontaneously transmits a radio signal, there is no need to request transmission of a radio signal from each vehicle unit to each sensor unit, for example. For this reason, it becomes possible to reduce the processing burden of the vehicle-mounted device. As the so-called spontaneous sensor unit, for example, the following two types can be adopted. One is to transmit a radio signal in response to the detection of the acceleration accompanying the rotation of the tire. The other is to transmit a radio signal at a predetermined transmission cycle. Regardless of the type, a radio signal is transmitted spontaneously based on a predetermined transmission condition. Note that the type that transmits a radio signal triggered by the detection of acceleration can save power consumption in the sensor unit, unlike the case where the radio signal is always transmitted. This is particularly effective when a battery is employed as the operating power supply for the sensor unit.

  <5> The invention according to claim 5 is the sensor unit registration system according to any one of claims 1 to 3, wherein each sensor unit is normally in a stopped state that does not emit the radio signal. On the other hand, upon receiving an activation command issued from the in-vehicle device, it activates and transmits the radio signal, and when the in-vehicle device detects any one of the marks, each sensor unit The gist is to wirelessly transmit the activation command.

  According to this configuration, when one mark is detected, a wireless signal is reliably transmitted from each sensor unit through transmission of an activation command to each sensor unit. Any one of these wireless signals always includes gravity acceleration information corresponding to the detected mark position. Therefore, the identification information included in the wireless signal together with the gravitational acceleration information is specified as being provided on the tire corresponding to the detected mark. Thus, unlike the case of waiting for the spontaneous transmission of a radio signal from each sensor unit, the registration process of identification information can be quickly performed by forcibly transmitting a radio signal from each sensor unit. The in-vehicle device may be configured to include an initiator (transmitter) that wirelessly transmits a start command, or may be provided separately.

  <6> The invention according to claim 6 is the sensor unit registration system according to any one of claims 1 to 5, wherein the in-vehicle device is a centrifugal acting on each sensor unit as the tire rotates. The gist is to execute the registration process of the identification information when a vehicle speed less than a threshold set with reference to a vehicle speed at which the force is sufficiently smaller than gravity is detected.

  According to this configuration, since the influence of the centrifugal force acting on each sensor unit is suppressed as the tire rotates, it is possible to detect accurate gravity acceleration. As a result, the mounting position of the sensor unit can be specified accurately and easily.

  <7> The invention according to claim 7 is the sensor unit registration system according to any one of claims 1 to 6, wherein the in-vehicle device is an existing rotation sensor that monitors the rotation of each tire. The gist of this is to detect the mark using.

  According to this configuration, the mark is detected using the existing rotation sensor. For this reason, it is possible to reduce the product cost of the system as compared to the case where a dedicated sensor for detecting the mark is provided.

  <8> The invention according to claim 8 is a sensor unit that is provided in each tire and transmits a radio signal including the air pressure information and identification information unique to itself, and monitors the air pressure of each tire based on these radio signals. In the sensor unit registration method for registering in an in-vehicle device, the sensor unit includes gravitational acceleration information corresponding to the rotational position of each tire in the wireless signal and can be transmitted. Each tire is mounted on a mounting target so that the sensor unit corresponds to a mark that can be visually recognized from the outside, and the vehicle-mounted device detects any one of the marks and corresponds to the one mark position. When a wireless signal including gravitational acceleration information is received, the identification information included in the wireless signal indicates the tire mounting position corresponding to the detected mark. As its gist to register in association with.

  According to this registration method, the same operation and effect as in claim 1 can be obtained.

  According to the present invention, the sensor unit of the tire pressure monitoring system can be easily registered in the vehicle.

The block diagram which shows schematic structure of the tire pressure monitoring system in this Embodiment. (A), (b) is a front view which similarly shows the position of the acceleration sensor accompanying rotation of a tire, (c) is a graph which shows the relationship between the rotation position of an acceleration sensor, and an output. The list figure which shows the structure of the table data similarly memorize | stored in the monitoring apparatus by the side of a vehicle. (A) is a perspective view showing the manner of attaching the tire, (b) is a front view showing a state where the disc is detected by the photosensor, and (c) is a front view showing a state where the disc is not detected by the photosensor. . The flowchart which similarly shows the procedure of the registration process of a sensor unit. (A), (b) is a front view of a disk showing a positional relationship between a cutout portion and a photosensor in another embodiment. The perspective view which shows the positional relationship of the mark and mark sensor in other embodiment. The schematic diagram which shows schematic structure of the wheel speed sensor in other embodiment. The block diagram which shows the registration system of the conventional sensor unit.

  Hereinafter, an embodiment in which the present invention is embodied in a vehicle tire pressure monitoring system will be described with reference to FIGS. In this example, a so-called direct type (valve type) in which a sensor unit provided integrally with an air valve of the tire is incorporated in the tire and the tire air pressure information directly detected by the sensor unit is wirelessly transmitted to the vehicle body side. The system is adopted.

<System overview>
First, an overview of the tire pressure monitoring system will be described. As shown in FIG. 1, the tire pressure monitoring system 11 includes four sensor units 14 provided on four tires 13 of a vehicle 12 and a monitoring device 16 provided on a vehicle body 15 of the vehicle 12. Each sensor unit 14 detects the air pressure of the tire 13 corresponding to itself, and transmits a wireless signal including the detected air pressure information and identification information unique to itself at a predetermined period. The radio signal from each sensor unit 14 is received by the monitoring device 16. The monitoring device 16 determines which of the four tires 13 the air pressure information included in the wireless signal is based on the identification information included in the received wireless signal. The monitoring device 16 individually monitors the air pressure of the four tires 13 based on each air pressure information. When an abnormality is detected in the air pressure of one of the tires, the fact that an abnormality has occurred in a specific tire is displayed through a display device 17 provided in a range that is visible to the driver in the passenger compartment, for example, an instrument panel or the like. Warning.

<Sensor unit>
The sensor unit 14 is integrally provided at the inner end of an air valve (not shown) of the tire 13. As shown in an enlarged view in the upper part of FIG. 1, the sensor unit 14 includes an acceleration sensor 21, an air pressure sensor 22, a transmitter 23, and a control circuit 24.

  The acceleration sensor 21 detects acceleration accompanying the rotation of the tire 13 or gravitational acceleration, and generates acceleration information that is an electrical signal corresponding to the detection result. The acceleration sensor 21 will be described in detail later. The air pressure sensor 22 measures the air pressure inside the tire 13 and generates air pressure information that is an electric signal corresponding to the measurement result. The transmitter 23 modulates the electrical signal generated in the control circuit 24 and wirelessly transmits the modulated electrical signal.

  The control circuit 24 comprehensively controls each part of the sensor unit 14. The storage device 25 of the control circuit 24 stores various control programs and identification information (ID code) unique to itself. The control circuit 24 generates an electrical signal including its own identification information, acceleration information acquired through the acceleration sensor 21, and air pressure information acquired through the air pressure sensor 22, and generates this electrical signal for a predetermined control period (for example, 60 seconds). ) To transmit as a radio signal through the transmitter 23.

  Here, the sensor unit 14 is operated by a battery (not shown). For this reason, in order to maintain the consumption of the battery and the life of the sensor unit 14 for a longer time, the sensor unit 14 is configured as follows. That is, the control circuit 24 stops the operation of the transmitter 23 when a change in acceleration through the acceleration sensor 21 is not detected for a predetermined time, such as when the vehicle is stopped. The control circuit 24 starts the operation of the transmitter 23 when a predetermined acceleration is detected through the acceleration sensor 21. Since the transmission of the radio signal through the transmitter 23 is stopped when the vehicle is stopped, the power of the battery is saved correspondingly.

<Acceleration sensor>
Next, the acceleration sensor 21 will be described in detail. The acceleration sensor 21 of this example employs a so-called single-axis type sensor that detects acceleration along a specific direction. The acceleration sensor 21 is provided such that its detection axis is along the radial direction of the tire 13. That is, the acceleration sensor 21 detects the acceleration along the radial direction of the tire 13. The acceleration sensor 21 detects the acceleration in the centrifugal direction with respect to the rotation center of the tire 13 as a negative (minus) acceleration, and similarly detects the acceleration in the centripetal direction as a positive (plus) acceleration.

  For example, as shown in FIG. 2A, when the acceleration sensor 21 is positioned at the top (12 o'clock position) of the tire 13 with the rotation of the tire 13 stopped, the acceleration sensor 21 has a centripetal direction of the tire 13. Gravity (1G) is applied. At this time, the acceleration sensor 21 detects 1G gravity acceleration as a positive acceleration. Further, as indicated by a two-dot chain line in the figure, when the acceleration sensor 21 is located at the bottom (6 o'clock position) of the tire 13, gravity is applied to the acceleration sensor 21 in the centrifugal direction of the tire 13. At this time, the acceleration sensor 21 detects 1G of gravitational acceleration as a negative acceleration. In other words, when an acceleration of ± 1 G is detected by the acceleration sensor 21, the acceleration sensor 21, and thus the sensor unit 14 provided with the acceleration sensor 21, is always present at the 12 o'clock position (0 °) or the 6 o'clock position (180 °). It can be said that.

  Further, as shown in FIG. 2B, when the acceleration sensor is located at the 3 o'clock position or the 9 o'clock position, gravity is applied to the acceleration sensor 21 in the tangential direction of the tire 13. That is, no acceleration acts on the acceleration sensor 21 in either the centrifugal direction or the centripetal direction of the tire 13. At this time, the acceleration sensor 21 detects 0G. In other words, when 0 G acceleration is detected by the acceleration sensor 21, the acceleration sensor 21, and thus the sensor unit 14 provided with the acceleration sensor 21, is always present at the 3 o'clock position (90 °) or the 9 o'clock position (270 °). I can say that.

  When the acceleration sensor 21 exists at a position other than these, the acceleration corresponding to the rotational position, that is, the gravity acceleration component in the centrifugal direction or the centripetal direction of the tire 13 is detected. This is the same even when the vehicle is decelerated to such an extent that gravity is sufficiently larger than the centrifugal force generated as the tire 13 rotates. In other words, the gravitational acceleration detected by the acceleration sensor 21 changes in a sine wave shape as shown in the graph of FIG. In the graph, the horizontal axis represents the rotational position of the acceleration sensor 21 during one rotation (360 °), and the vertical axis represents the detection value (gravity acceleration) of the acceleration sensor 21. However, the detected value is corrected so as to cancel out the centrifugal force generated by the rotation of the tire 13.

<Monitoring device>
Next, the monitoring device 16 will be described in detail. As shown in FIG. 1, the monitoring device 16 includes a receiver 31 and a control device 32. The receiver 31 receives a radio signal from each sensor unit 14. The control device 32 performs overall control of the system. The control device 32 monitors the state of each tire 13 based on the radio signal received through the receiver 31.

  The storage device 33 of the control device 32 stores table data 34 shown in FIG. The table data 34 is information indicating a correspondence relationship between the mounting positions (right front, left front, right rear, and left rear) of the tires 13 and the identification information ID1 to ID4 of the sensor units 14. The table data 34 is registered when the vehicle is shipped or the tire 13 is replaced. The storage device 33 stores various control programs.

  The control device 32 determines which of the tires 13 the air pressure information included in the wireless signal is based on the comparison between the identification information included in the wireless signal received through the receiver 31 and the table data 34. . Moreover, the control apparatus 32 determines the presence or absence of abnormality of the air pressure of each tire 13 based on the said air pressure information. When an abnormality is detected in the air pressure of any one of the tires 13, the control device 32 generates a display control signal to warn to that effect. The display device 17 displays a warning that an abnormality has occurred in a specific tire in accordance with a display control signal generated by the control device 32.

  Further, the control device 32 can detect the rotational position of each tire 13. A configuration for this purpose is provided on the vehicle body 15 side. That is, as shown in FIG. 4A, a disc 42 to which the tire 13 is attached is provided at the tip of each axle 41. Five bolts project from the outer surface of the disk 42. The tire 13 is fixed to the disc 42 by inserting the tire 13 (to be exact, the wheel) through these bolts and tightening with a nut from the outside.

  A single notch 43 is formed on the outer peripheral edge of the disk 42. Further, a photo sensor (photo interrupter) 44 for detecting the cutout 43 is fixed to the vehicle body 15. In this example, the photosensor 44 is provided so as to correspond to the top portion (12 o'clock position) of the tire 13. As shown in FIGS. 4B and 4C, the photosensor 44 is assembled in a single case with the light emitting element 45 and the light receiving element 46 facing each other. The photo sensor 44 is provided such that the light emitting element 45 and the light receiving element 46 sandwich the outer peripheral edge of the disk 42 therebetween. The photo sensor 44 detects the presence or absence of an object depending on whether or not the light from the light emitting element 45 is received by the light receiving element 46.

  As shown in FIG. 4B, when a disk 42 (exactly its outer peripheral edge) exists between the light emitting element 45 and the light receiving element 46, the light from the light emitting element 45 is transmitted to the disk 42. Therefore, the light is not received by the light receiving element 46. In this case, it is detected that the disk 42 exists between the light emitting element 45 and the light receiving element 46, in other words, the notch 43 does not exist. In addition, as shown in FIG. 4C, when the disk 42 does not exist between the light emitting element 45 and the light receiving element 46, in other words, when the notch 43 exists, the light from the light emitting element 45 Passes through the notch 43 and is received by the light receiving element 46. In this case, it is detected that the disk 42 does not exist between the light emitting element 45 and the light receiving element 46, in other words, the presence of the notch 43.

  As described above, since the photosensor 44 is provided at the 12 o'clock position, the notch 43 is present every time it reaches the 12 o'clock position as the tire 13 (more precisely, the disk 42) rotates. Is detected.

  The control device 32 detects the rotation position of the tire 13 through the presence / absence of the detection of the notch 43 through the photosensor 44, that is, the rotation position when the notch 43 is present at the 12 o'clock position, and The rotational position when it exists at the position is detected. The rotational position information of the tire 13 detected through the photosensor 44, more precisely, information related to the presence / absence of detection of the notch 43 is used for a sensor unit registration process to be described later.

<Sensor unit registration process>
Now, when the tire 13 is newly purchased, it is necessary to update the table data 34 shown in FIG. 3 according to the attachment position of the new sensor unit 14. The same applies to the case of tire rotation. In this example, after the tire 13 is replaced, the new sensor unit 14 mounting position is automatically newly registered or updated in the storage device 33 of the control device 32 during normal traveling of the vehicle.

  Next, the registration process of the sensor unit 14 will be described with reference to the flowchart of FIG. This flowchart is executed in accordance with a control program stored in the storage device of the control device 32. When the tire 13 is newly purchased, the four tires 13 are all attached with the positions of the notch 43 and the air valve (sensor unit 14) being matched.

  Now, as shown in the flowchart of FIG. 5, in the state where the vehicle speed is less than the predetermined threshold value, it is determined whether or not a radio signal is received from each sensor unit 14 (step S101). The threshold value is set from the viewpoint of detecting a state where the vehicle is decelerated to such an extent that gravity is sufficiently larger than the centrifugal force generated by the rotation of the tire 13. In this example, the threshold value is set to a value of about 3 to 5 km / h. As described above, the sensor unit 14 starts transmission of a radio signal through the transmitter 23 when a predetermined acceleration is detected through the acceleration sensor 21. This is because the vehicle speed is less than the threshold value. This is also true when the acceleration associated with the rotation of the tire 13 is detected. Each sensor unit 14 transmits a radio signal when acceleration is detected as each tire 13 rotates.

  If it is determined that the vehicle speed is not less than the threshold value, or if it is determined that the vehicle speed is less than the threshold value (NO in step S101), the process is terminated.

  When it is determined that the vehicle speed is less than the threshold and a wireless signal has been received (YES in step S101), the positions of the notches 43 corresponding to the four tires 13 are confirmed. Then, it is determined whether only one of the four photosensors 44 has detected the cutout 43 (step S102).

  If it is determined that two or more photosensors 44 have detected the notch 43 or that no notch 43 has been detected (NO in step S102), the process is terminated.

  When it is determined that only one photosensor 44 has detected the cutout 43 (YES in step S102), whether acceleration information (absolute value) included in the received radio signal indicates 1G of gravitational acceleration It is determined whether or not (step S103).

When it is determined that there is no information indicating 1G in the acceleration information included in the received wireless signal (NO in step S103), the process ends.
When it is determined that there is one indicating 1G in the acceleration information (YES in step S103), the attachment position of the sensor unit 14 corresponding to the identification information included in the wireless signal is specified together with the acceleration information (step S104). ). That is, the identification information of the sensor unit 14 included in the wireless signal together with the acceleration information indicating 1G as the gravitational acceleration is associated with the mounting position of the tire 13 corresponding to the photosensor 44 that detected the notch 43 in the previous step S102. And stored in the storage device 33 of the control device 32.

  The attachment position is specified based on the fact that 1G acceleration information is always obtained from the tire 13 corresponding to the photosensor 44 that has detected the notch 43 in the previous step 102. That is, in this example, when the tire 13 is attached to the vehicle body 15, the position of the notch 43 and the position of the air valve (sensor unit 14) are made to coincide. The photosensor 44 is provided so as to correspond to the 12 o'clock position of the tire 13. For this reason, when the notch 43 is detected by the photosensor 44, the notch 43 is present corresponding to the 12 o'clock position of the tire 13. When the notch 43 is present at the 12 o'clock position, the sensor unit 14 is also positioned corresponding to the 12 o'clock position of the tire 13, so that the acceleration sensor 21 of the sensor unit 14 has a gravitational acceleration of 1 G in the vertical direction. Applied. Therefore, when the notch 43 is detected by a specific photosensor 44 and acceleration information indicating 1G is included in any of the wireless signals received at that time, it corresponds to the identification information included in the wireless signal. It can be said that the sensor unit 14 is provided on the tire 13 corresponding to the photosensor 44 that detects the notch 43. Using this fact, the attachment position of the tire 13 to which the sensor unit 14 is attached is specified.

  When the vehicle travels, the rotational angular velocities of the four tires 13 are slightly different from each other due to the fact that the vehicle is provided with a differential gear (differential gear) that absorbs the inner ring difference. For this reason, after exchanging tires and the like, the registration of the four sensor units 14 is performed as appropriate by repeating a series of steps S101 to S104 during normal travel. There is no need to perform any special registration operation, and registration of all the sensor units 14 is completed, which is convenient.

<Effect of Embodiment>
Therefore, according to the present embodiment, the following effects can be obtained.
(1) When the tire 13 is replaced, the user only needs to attach the tire 13 to the disk 42 to be attached so that the notch 43 and the sensor unit 14 (air valve) coincide with each other. Thereafter, as the vehicle travels, the attachment position of the sensor unit 14 is specified based on the presence or absence of the detection of the notch 43 and the acceleration information included in the wireless signal from the sensor unit 14. That is, when a radio signal including gravitational acceleration information corresponding to the position of the notch 43 is received in a state where one notch 43 is detected, the sensor unit 14 that has transmitted the radio signal is detected. It can be seen that this is provided on the tire 13 corresponding to the notch 43. This is because the notch 43 and the sensor unit 14 are provided so as to correspond to each other, and therefore the gravitational acceleration corresponding to the position of the notch 43 acts on the sensor unit 14 corresponding to the detected notch 43. It is. Then, the identification information is registered in the in-vehicle monitoring device 16 in association with the specified mounting position of the sensor unit 14. Thus, the user does not need to perform a special registration operation or the like, and can easily register the sensor unit 14 in the vehicle.

  (2) The sensor unit 14 employs a so-called spontaneous type that spontaneously transmits a radio signal when acceleration accompanying rotation of the tire 13 is detected. For this reason, unlike the case where a radio signal is always transmitted, power consumption in the sensor unit 14 can be saved. This is particularly effective when a battery is employed as an operating power source for the sensor unit 14.

  (3) The monitoring device 16 is in a state in which a vehicle speed less than a threshold set based on a vehicle speed that is assumed to have a centrifugal force acting on each sensor unit 14 sufficiently smaller than gravity as the tire 13 rotates is detected. The registration process of the sensor unit 14 is executed. That is, since the influence of the centrifugal force acting on each sensor unit 14 with the rotation of the tire 13 is suppressed, accurate gravity acceleration can be detected. As a result, the mounting position of the sensor unit 14 can be accurately and easily specified.

  (4) It is only necessary to form the notch 43 in the disk 42 and dispose the photo sensor 44 in the vicinity thereof. For this reason, the configuration of the tire pressure monitoring system 11 is not greatly complicated. That is, the registration work of the sensor unit 14 can be simplified while simplifying the system configuration.

<Other embodiments>
The embodiment described above may be modified as follows.
In the flowchart of FIG. 5, the processing order of step S102 and step S103 may be reversed. That is, when acceleration information indicating 1G is received on the vehicle side, any one of the cutout portions 43 corresponding to the four tires 13 must be present at a position corresponding to the 12 o'clock position of the tire 13. is there. In other words, any one of the four photosensors 44 always detects the notch 43. The mounting position of each photosensor 44, that is, to which tire 13 each photosensor 44 corresponds is known. For this reason, it is specified that the sensor unit 14 having the identification information included in the wireless signal together with the 1G acceleration information is provided on the tire 13 corresponding to the photosensor 44 detecting the notch 43. .

  In this example, the length (formation range) of the notch 43 in the rotation direction of the disk 42 may be set as appropriate. For example, as shown in FIG. 6A, the formation range L of the notch 43 may be set small enough to allow the photosensor 44 to exchange light. In this case, the cutout portion 43 is detected by the photosensor 44 only when it comes to the 12 o'clock position accurately. At this time, a gravitational acceleration closer to 1 G is applied to the acceleration sensor 21 of the sensor unit 14. That is, the acceleration information included in the radio signal transmitted from the sensor unit 14 indicates an acceleration that is more approximate to 1G. For this reason, it becomes easy to judge that it shows 1G of gravitational acceleration in judgment of previous step S103 of FIG.

  Conversely, as shown in FIG. 6B, the formation range L of the notch 43 may be set larger than the main body of the photosensor 44. For example, when the number of bolts of the disk 42 is 5, the formation range L of the notch 43 may be expanded to about 72 ° which is the arrangement interval. In this way, the chance of detecting the notch 43 can be increased. In this case, it is preferable to give a width to the determination criterion in step S <b> 103 in the flowchart of FIG. 5 according to the formation range of the notch 43. For example, when the formation range of the notch 43 is 72 ° and the 12 o'clock position is 0 °, the notch 43 is detected while rotating by 36 ° counterclockwise and 36 ° clockwise. . When the tire 13 rotates by 36 ° in the clockwise direction and in the counterclockwise direction, the gravitational acceleration detected by the acceleration sensor 21 has the same value smaller than 1G, for example, by α (α <1G). A width is given to the determination criterion in step S103 by the amount of α.

  In this example, the single photosensor 44 is provided at the 12 o'clock position, but the photosensor 44 may also be provided at the 6 o'clock position. Opportunities for the acceleration sensor 21 of the sensor unit 14 to detect 1G gravitational acceleration are when the acceleration sensor 21 is located at the top (12 o'clock position) of the tire 13 and when it is also located at the bottom (6 o'clock position). Exists twice. When the acceleration sensor 21 is present at the 12 o'clock position and when it is present at the 6 o'clock position, the direction of acceleration is opposite, but the case where the acceleration sensor 21 is present at the 6 o'clock position is also the flowchart of FIG. By making it the detection target in step S102, it becomes possible to double the detection opportunity of the notch 43. Therefore, registration of each sensor unit 14 is performed more quickly.

  In this example, the notch 43 is formed in the disk 42 and the notch 43 is detected by the photosensor 44, but the following configuration may be adopted instead. That is, the mark 47 is provided on a part of the outer peripheral edge of the disk 42 so as to be visible from the outside. Further, a photoelectric sensor 48 or the like is provided as a mark sensor for detecting the mark 47. The photoelectric sensor 48 is provided so as to be able to detect the mark 47 present at the 12 o'clock position, as in this example. And when attaching the tire 13, the said mark 47 and the air valve (sensor unit 14) are made to correspond.

  In this example, the notch 43 and the photo sensor 44 are provided as dedicated products for the registration process of the sensor unit 14, but existing equipment mounted on the vehicle may be used. For example, a wheel speed sensor used in various vehicle stability control systems (such as an antilock brake system) may be used. This wheel speed sensor monitors the rotation of the tire, and generates a pulse signal corresponding to the rotation of the tire. In this case, a mark as shown in FIG. This mark is set only at one location of the disk 42 as in the cutout portion 43 of this example. Then, the tire 13 is attached so that the mark and the air valve (sensor unit 14) coincide. By storing in advance the rotation angle of the tire 13 when the mark is present at a specific rotation position in the storage device 33 of the control device 32, the tire 13 is utilized using the tire rotation pulse generated by the wheel speed sensor. It is possible to determine whether or not the mark is present at, for example, the 12 o'clock position (0 °) by detecting the rotation angle of the mark and thus the rotation angle of the mark by an absolute value. As the wheel speed sensor, there are optical and electromagnetic sensors, and any of them may be used.

  It is also possible to detect the position of the mark as follows using the above-described existing wheel speed sensor. That is, as shown in FIG. 8, the wheel speed sensor includes a gear pulser 51 that rotates integrally with the axle 41, and a magnetic sensor 52 that rotates relative to the peripheral surface thereof. The gear pulser 51 is formed in a gear shape from a ferromagnetic material such as iron. A large number of teeth 53 are formed at a predetermined pitch on the outer peripheral surface of the gear pulser 51. Of these teeth 53, only one of the teeth 53a is formed of a ferromagnetic material having a higher magnetic permeability than other portions, such as permalloy. Then, a mark as shown in FIG. 7 is provided on the disk 42 so as to be visible from the outside so as to coincide with the specific tooth 53a. The magnetic sensor 52 includes a permanent magnet 54 that generates a magnetic field, a coil 55 that generates an electromotive force in response to a change in the magnetic field formed by the permanent magnet 54, and a magnetic flux collecting core (core) that is inserted into the coil 55. 56. The coil 55 is disposed between the gear pulser 51 and the permanent magnet 54 with the iron core 56 inserted.

  Now, when the gear pulser 51 rotates with rotation of the axle 41, the teeth 53 of the gear pulser 51 repeat separation and approach with respect to the coil 55. That is, the peak portion (convex) and the valley portion (concave) of the gear pulser 51 correspond to the coil 55 alternately. As a result, the number of lines of magnetic force passing through the iron core 56 of the coil 55 disposed between the permanent magnet 54 and the gear pulser 51 is repeatedly increased and decreased. This is because the magnetic lines of force from the permanent magnet 54 are easy to pass when the peak portion of the gear pulser 51 approaches the iron core 56, and the magnetic lines of force from the permanent magnet 54 are difficult to pass when the valley portion approaches the iron core 56. As a result, AC power is generated in the coil 55. Since the frequency of this AC power is proportional to the rotational speed of the axle 41, the rotational speed of the axle 41 can be obtained by measuring the frequency. Also, the rotation angle can be obtained.

  Further, here, one specific tooth 53a among the multiple teeth 53 of the gear pulser 51 is formed of a magnetic material having a higher magnetic permeability than the other parts. For this reason, when the coil 55 corresponds to the specific tooth 53a, a higher output (electromotive force) is obtained than when the coil 55 corresponds to the other tooth 53. Therefore, it is possible to identify one location during one rotation of the gear pulser 51. For example, when the magnetic sensor 52 is provided at the 12 o'clock position of the gear pulser 51, it is possible to determine whether or not a mark provided on the disk 42 corresponding to the specific tooth 53a exists at the 12 o'clock position. In this way, by using an existing wheel speed sensor used in an antilock brake system or the like, it is possible to reduce the product cost of the system as compared with the case where a sensor dedicated to a tire pressure monitoring system is provided. is there.

  In order to function as a wheel speed sensor for an anti-lock brake system or the like, an electrical signal having a frequency corresponding to the unevenness of the gear pulser 51 may be obtained. That is, since the signal amplitude does not matter in the antilock brake system, an electric signal with a high amplitude corresponding to a specific tooth 53 a is processed in the same manner as an electric signal with a low amplitude corresponding to another tooth 53. Forming only the specific teeth 53a with a ferromagnetic material having a high magnetic permeability does not affect the antilock brake system or the like.

  Some wheel speed sensors include a signal processing circuit that converts the output of the coil 55 into a pulse signal. Even in this case, the wheel speed sensor can be used in the same manner. When the gear pulser 51 rotates, a pulse signal corresponding to the unevenness passing through the magnetic sensor 52 is generated. The rotational speed and rotational angle of the axle 41 can be calculated from the number of pulses per unit time. Further, when a specific tooth 53a comes close to the magnetic sensor 52, only one pulse signal having a high wave height is generated. Based on this signal, it is possible to specify one place in one rotation of the gear pulser 51.

  Furthermore, contrary to the above, only one specific tooth 53a out of the many teeth 53 of the gear pulsar 51 may be formed of a magnetic material having a lower magnetic permeability than the other parts. In this case, when the coil 55 corresponds to the specific tooth 53a, a lower output (electromotive force) is obtained than when the coil 55 corresponds to the other tooth 53. Therefore, it is possible to identify one location during one rotation of the gear pulser 51.

  In this example, the sensor unit 14 employs a so-called spontaneous type that spontaneously transmits a radio signal including air pressure information, etc., triggered by detection of acceleration. Good. In this case, a single initiator (transmitter) 49 is provided in the vehicle as indicated by a two-dot chain line on the left side of the monitoring device 16 in FIG. Each sensor unit 14 is normally maintained in a stopped state that does not emit a radio signal, and is activated in response to an activation command issued from the initiator 49 to transmit a radio signal. The initiator 49 wirelessly transmits a start command or a stop command to each of the four sensor units 14. When the sensor unit 14 receives the activation command, the sensor unit 14 starts transmitting a radio signal including the air pressure information of the tire 13 and the like. When the sensor unit 14 receives the stop command, the sensor unit 14 stops the transmission of the radio signal. When the vehicle control device 32 detects through the four photosensors 44 that any one of the four cutouts 43 has reached the 12 o'clock position, the vehicle control device 32 issues an activation command to the four sensor units 14 through the initiator 49. Is transmitted wirelessly. Since one notch 43 is present at the 12:00 position, the wireless signal from the sensor unit 14 provided on the tire 13 corresponding to the notch 43 includes acceleration information indicating 1G. It should be. That is, the control device 32 can reliably acquire a radio signal including acceleration information indicating 1G. Further, unlike the case of waiting for the spontaneous transmission of radio signals from each sensor unit 14, the control device 32 quickly attaches each sensor unit 14 by forcibly transmitting a radio signal from each sensor unit 14. The position can be specified. As a result, the registration process of the sensor unit 14 can be performed quickly. This is similarly applicable to the case where the mark sensor in the above-described modification is used. Each sensor unit 14 may transmit a radio signal at the same time through reception of an activation command. However, the sensor unit 14 may transmit the radio signal with a time difference based on the reception of the activation command. It is possible to suppress the occurrence of interference. The initiator 49 and the monitoring device 16 constitute an in-vehicle device of the present invention.

  In this example, the sensor unit 14 employs a sensor that spontaneously transmits a radio signal triggered by the detection of acceleration. However, the sensor unit 14 does not react to acceleration and spontaneously transmits a radio signal at a predetermined time interval. Other spontaneous types may be adopted.

  The photo sensor 44 of this example detects the notch 43 that exists at the 12 o'clock position, but may detect the notch 43 at an arbitrary position. Since the position where the notch 43 is detected is determined by the position where the photosensor 44 is provided, it is possible to calculate in advance the gravitational acceleration applied to the acceleration sensor 21 when the notch 43 is detected by the photosensor 44. is there. And the control apparatus 32 specifies that the sensor unit 14 which transmitted the radio signal containing the calculated acceleration information is provided on the tire 13 corresponding to the photosensor 44 that has detected the notch 43. Can do. The same applies to the case where the mark sensor in the above-described modification is used.

<Other technical ideas>
Next, the technical idea that can be grasped from the above embodiment will be added below.
(A) In the sensor unit registration system according to any one of claims 1 to 6, the sensor unit registration system includes a mark sensor that detects the mark, and the mark sensor is provided at a twelve o'clock position corresponding to the top of the tire. Sensor unit registration system.

  According to this configuration, each mark is detected by the mark sensor at the 12 o'clock position. Since the mark and the sensor unit are provided corresponding to each other, the gravitational acceleration acting on the sensor unit at this time is 1G or an approximation thereof. For this reason, it is possible to specify that the sensor unit that has transmitted the wireless signal including the 1G gravity acceleration information is provided on the tire corresponding to the mark detected by the mark sensor.

  (B) In the sensor unit registration system according to claim 7 or (a), the rotation sensor includes a gear pulser that rotates integrally with an axle, and a magnetic sensor that converts unevenness formed on a peripheral surface of the gear pulser into an electric signal. A sensor unit registration system comprising: An existing rotation sensor having such a configuration can also be employed.

  DESCRIPTION OF SYMBOLS 11 ... Tire pressure monitoring system (sensor unit registration system), 13 ... Tire, 14 ... Sensor unit, 16 ... Monitoring apparatus (vehicle equipment), 43 ... Notch part (mark).

Claims (8)

In a sensor unit registration system for registering a sensor unit that is provided in each tire and transmits a wireless signal including air pressure information and identification information unique to itself in an in-vehicle device that monitors the air pressure of each tire based on these wireless signals,
Each sensor unit corresponds to a mark provided so as to be visible from the outside with respect to an attachment target of each tire, and includes gravitational acceleration information according to the rotation position of each tire in the wireless signal, and can be transmitted.
When the vehicle-mounted device detects any one of the marks and receives a radio signal including gravitational acceleration information corresponding to the one mark position, the in-vehicle device detects the identification information included in the radio signal. Sensor unit registration system that registers in association with the mounting position of the tire corresponding to. In the sensor unit registration system according to claim 1,
When the vehicle-mounted device detects any one of the marks and receives a wireless signal including acceleration information corresponding to the detected position of the mark, the in-vehicle device corresponds to the detected mark with the identification information included therein. Sensor unit registration system that registers in association with the mounting position of the tire to be used. In the sensor unit registration system according to claim 1,
When the vehicle-mounted device receives a radio signal including acceleration information corresponding to a specific mark position, the identification information included in the vehicle-mounted device is attached to a tire corresponding to the mark detected to be present at the specific position; Sensor unit registration system that registers and associates. In the sensor unit registration system according to any one of claims 1 to 3,
The sensor unit is a sensor unit registration system that spontaneously transmits the wireless signal. In the sensor unit registration system according to any one of claims 1 to 3,
Each sensor unit is normally maintained in a stopped state that does not emit the radio signal, while receiving the activation command issued from the in-vehicle device to start and transmit the radio signal,
The on-vehicle device is a sensor unit registration system that wirelessly transmits the activation command to each sensor unit when detecting any one of the marks. In the sensor unit registration system according to any one of claims 1 to 5,
When the vehicle speed below a threshold set on the basis of the vehicle speed at which the centrifugal force acting on each sensor unit is sufficiently smaller than gravity is detected as the tire rotates, the vehicle-mounted device registers the identification information. A sensor unit registration system that executes. In the sensor unit registration system according to any one of claims 1 to 6,
The in-vehicle device is a sensor unit registration system that detects the mark using an existing rotation sensor that monitors the rotation of each tire. In a sensor unit registration method for registering a sensor unit that is provided in each tire and transmits a wireless signal including the air pressure information and identification information unique to itself in an in-vehicle device that monitors the air pressure of each tire based on these wireless signals,
The sensor unit includes gravitational acceleration information corresponding to the rotational position of each tire in the wireless signal and can be transmitted.
Each tire is mounted on the mounting target so that the sensor unit corresponds to a mark that can be visually recognized from the outside with respect to the mounting target of each tire.
When the vehicle-mounted device detects any one of the marks and receives a radio signal including gravitational acceleration information corresponding to the one mark position, the in-vehicle device detects the identification information included in the radio signal. Sensor unit registration method for registering in association with the mounting position of the tire corresponding to.

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