JP2014121983A - Tire position determination system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire position determination system capable of ensuring communication establishment performance of a radio wave transmitted from a tire air pressure detector at a time of determining a tire position.SOLUTION: A detector rotational-angle calculation unit 26 of each of tire air pressure detectors 4 (4a to 4d) calculates a rotational angle (detector rotational angle) formed by the tire air pressure detector 4 between a first stop and a second stop on the basis of a gravity component force detected by an acceleration sensor 10. The detector rotational angle is calculated for each of the tire air pressure detectors 4a to 4d. A delay time setting unit 27 of each of the tire air pressure detectors 4a to 4d sets delay time when an auto location signal Sal is transmitted, in response to the detector rotational angle. The tire air pressure detectors 4a to 4d transmit the auto location signals Sal in which the delay time is reflected, at respective timing.

Description

  The present invention relates to a tire position determination system that determines the position of each tire required to monitor the air pressure of each tire.

  Conventionally, a tire pressure detector that detects tire pressure and wirelessly transmits it is attached to each tire, and the tire pressure signal transmitted from the tire pressure detector is received by the vehicle body receiver to monitor the tire pressure. Direct tire pressure monitoring systems are well known. In the case of this type of tire pressure monitoring system, there is a need to know the tire position in order to notify the position of the low-pressure tire, but the tire is replaced or replaced with a new tire. Therefore, it is considered to install an auto-location function that periodically checks the tire position. As an auto-location function, for example, there is a method of determining the position of the tire by attaching an initiator (trigger) to each tire house and selectively transmitting a radio wave to the tire pressure detector by a radio wave transmitted from the initiator. It is well known (see Patent Documents 1 and 2).

JP 2006-062516 A JP 2012-126341 A

  However, the auto-location function using an initiator requires that an initiator be provided in each tire house. Therefore, in the auto location function using the initiator, there are concerns about problems such as an increase in the number of parts and an increase in parts cost.

  Therefore, the present applicant has devised a technique for determining the tire position using the rotational speed information of the axle and the gravity information of the tire pressure detector without using an initiator. In this method, for example, the rotation speed information of the axle and the gravity information of the tire pressure detector are acquired at the time of the first (first) parking and stopping, and the rotation speed information of the axle is similarly obtained at the second (second) parking and stopping. Is compared with the gravity information of the tire pressure detector and the rotation angle obtained from the difference between the first and second axle speed information and the rotation obtained from the difference between the first and second tire pressure detectors. This is a technique for determining a tire position by comparing with a corner.

  However, since the general tire pressure detector transmits the gravity information at the time of stopping by radio wave, for example, if the transmission timing is accidentally synchronized, the gravity information transmitted from these tire pressure detectors will collide. There was a current situation. Therefore, gravity information cannot be acquired from these tire air pressure detectors, and the determination of the tire position may not be completed.

  As described above, the present invention is an improved invention of Japanese Patent Application No. 2011-209509 and Japanese Patent Application No. 2012-202243, which are application cases of the present applicant, and the tire pressure detector is operated only periodically. It is an invention aimed at solving various problems such as 1) inability to complete the auto-location function and 2) shortening the battery life of the tire pressure detector.

  An object of the present invention is to provide a tire position determination system that can ensure communication feasibility of radio waves transmitted from a tire air pressure detector at the time of tire position determination.

  A tire position determination system that solves the above problem transmits a tire air pressure signal from a tire air pressure detector attached to each tire, and receives the tire air pressure signal at a receiver of the vehicle body to monitor the tire air pressure. In the tire position determination system, which is a function of the tire pressure monitoring system and determines the position of the tire from the position of the tire pressure detector, the axle rotation speed detected by the axle rotation speed detection unit at the first stop and the second time The axle rotation angle calculated from the axle rotation speed detected by the axle rotation speed detection unit at the time of stopping, the gravitational force generated in the tire air pressure detector at the time of the first stop, and the tire at the time of the second stop Auto-location that determines the position of the tire based on the detector rotation angle calculated from the gravitational force generated in the air pressure detector It includes a down function unit, the transmission timing for sending radio waves to be used to determine the tire position from the tire pressure detector, equipped with a radio transmission timing setting unit for setting in response to the detector rotation angle.

  According to this configuration, since the transmission timing when transmitting the radio wave used for determining the tire position from the tire pressure detector is set according to the detector rotation angle, the radio wave is shifted from each tire pressure detector. Can be transmitted. Thus, radio waves transmitted from the tire air pressure detector at the time of tire position determination are less likely to collide, so that the establishment of communication can be ensured.

  In the tire position determination system, it is preferable that the radio wave transmission timing setting unit shifts transmission timings of radio waves transmitted from the tire pressure detectors by setting a delay time corresponding to the detector rotation angle. According to this configuration, it is possible to vary the timing of radio wave transmission by a simple method of setting a delay time.

  In the tire position determination system, the tire air pressure detector uses a detection signal of a gravity component detection unit capable of detecting the gravity component force, a traveling state determination unit that determines a traveling state of the vehicle, and the traveling state An operation mode switching unit that switches an operation mode of the tire air pressure detector is preferably provided based on a determination result of the determination unit. According to this configuration, based on the determination result of the traveling state determination unit, the operation mode of the tire air pressure detector can be switched from the normal air pressure determination mode to the auto location determination mode, which is a dedicated tire position determination mode. . Therefore, when the tire position is determined by the auto-location function unit, the tire air pressure detector can be operated in a mode suitable for the tire position determination, so that the tire position determination can be completed in an optimal operation mode. .

  In the tire position determination system, the operation mode switching unit changes the operation mode of the tire air pressure detector from an air pressure determination mode for monitoring the tire air pressure when the vehicle speed of the vehicle being traveled is reduced below a threshold value. It is preferable that the auto location determination mode for determining the position of the tire is set, and the radio wave transmission timing setting unit sets the radio wave transmission timing in the auto location determination mode. According to this configuration, when the vehicle speed is reduced below the threshold value, the operation mode of the tire air pressure detector is switched to the auto location determination mode suitable for determining the tire position. Therefore, it is possible to accurately determine the tire position performed when the vehicle is decelerated.

  In the tire position determination system, the auto location determination mode is set such that a periodic radio wave transmission interval is shorter than that in the air pressure determination mode, and the tire pressure detector is in the auto location determination mode. It is preferable that the gravitational force is transmitted to the vehicle body at the short transmission interval. According to this configuration, the periodic radio wave transmission interval in the auto location determination mode is set to be shorter than that in the air pressure determination mode, so even if the stop time is short, such as when waiting for a signal, It is possible to make radio transmission in time.

  In the tire position determination system, it is preferable that the delay time is set to a value that is relatively prime to each tire pressure detector or a value that the least common multiple does not exceed the stop time. According to this configuration, at the time of tire position determination, it further contributes to the prevention of collision of radio waves transmitted from each tire pressure detector.

  ADVANTAGE OF THE INVENTION According to this invention, the establishment of communication of the electromagnetic wave transmitted from a tire air pressure detector at the time of tire position determination can be ensured.

The block diagram of the tire position determination system of one Embodiment. The conceptual diagram of the gravity component force detected with a tire air pressure detector. (A), (b) is explanatory drawing of an axle shaft rotation angle. (A), (b) is explanatory drawing of a detector rotation angle. The wave form diagram which shows the operation | movement image of the mode switching of a tire pressure detector. A table summarizing the operation details of the air pressure judgment mode. A table that summarizes the operation contents of the auto location determination mode. The flowchart performed at the time of auto location determination. The table | surface which put together an example of the delay time set according to a detector rotation angle. (A)-(c) is explanatory drawing of a motion when gravity component force decreases monotonously. (A)-(c) is explanatory drawing of a motion when gravity component force increases monotonously.

Hereinafter, an embodiment of a tire position determination system will be described with reference to FIGS.
As shown in FIG. 1, the vehicle 1 is provided with a tire pressure monitoring system (TPMS: Tire Pressure Monitoring System) 3 that monitors the tire air pressure and the like of each tire 2 (2a to 2d). In the tire pressure monitoring system 3 of this example, tire pressure detectors 4 (4a to 4d: also referred to as tire valves) are provided for the tires 2a to 2d, and tire pressure signals Stp detected by the tire pressure detectors 4a to 4d are provided. Is wirelessly transmitted to the vehicle body 5 to directly monitor the tire pressures of the tires 2a to 2d in the vehicle body 5.

  The tire pressure detectors 4a to 4d are provided with a controller 6 that controls the operation of the tire pressure detectors 4a to 4d. In the memory 7 of the controller 6, a tire ID (also referred to as a valve ID) is written and stored as a unique ID of each tire 2a to 2d. The tire pressure detectors 4a to 4d are provided with a pressure sensor 8 for detecting tire pressure, a temperature sensor 9 for detecting tire temperature, and an acceleration sensor 10 for detecting acceleration (rotation) generated in the tire 2, These are connected to the controller 6. The controller 6 is connected to a transmission antenna 11 capable of transmitting a radio wave in the UHF (Ultra High Frequency) band. The acceleration sensor 10 is an example of a gravitational component force detection unit.

  The vehicle body 5 is provided with a receiver (hereinafter referred to as a TPMS receiver) 12 that receives the tire pressure signals Stp transmitted from the tire pressure detectors 4a to 4d and monitors the tire pressure. The TPMS receiver 12 is provided with a tire pressure monitoring ECU (Electronic Control Unit) 13 that controls the operation of the TPMS receiver 12 and a receiving antenna 14 that can receive UHF radio waves. In the tire 15 of the tire pressure monitoring ECU 13, tire IDs of the respective tires 2a to 2d are written and stored in association with tire positions (right front, left front, right rear, and left rear). For example, a display unit 16 installed on an in-vehicle instrument panel or the like is connected to the TPMS receiver 12.

  When the tire pressure detector 4 confirms that the tire 2 has entered the rotation state based on the detection signal from the acceleration sensor 10, or at regular or irregular intervals with a predetermined time interval, the tire pressure detector Stp Send to 5. Whether or not the tire 2 has entered the rotating state is determined by checking whether or not the acceleration (gravity) applied to the tire air pressure detector 4 has changed. Further, even when it is determined that the tire 2 does not rotate, the tire air pressure signal Stp is transmitted at an interval equal to or longer than that at the time of rotation.

  As shown in FIG. 1, the tire pressure monitoring system 3 is provided with a tire position determination system 17 that determines at which position the tires 2a to 2d are attached at the front, rear, left and right positions. In the case of this example, the tire pressure monitoring ECU 13 includes axle speed information acquired from the axle speed detection sensor 19 (19a to 19d) attached to each axle 18 (18a to 18d) of the tire 2a to 2d, and the tire. An auto-location function unit 20 that determines the front / rear / left / right mounting positions of the tires 2a to 2d using gravity information detected by the acceleration sensors 10 of the air pressure detectors 4a to 4d is provided. The auto-location function unit 20 periodically executes position determination (auto-location determination) of the tires 2a to 2d in a predetermined cycle. The axle rotation speed detection sensor 19 (19a to 19d) is an example of the axle rotation speed detection unit.

  As the axle rotation speed detection sensors 19a to 19d, for example, ABS (Antilock Brake System) sensors are used. For example, the axle rotation speed detection sensors 19a to 19d sequentially detect a plurality of teeth (for example, 48) attached to the axles 18a to 18d by the sensing unit on the vehicle body 5 side, thereby generating a rectangular wave pulse signal Spl. Output to the TPMS receiver 12. The axle rotation speed detection sensors 19a to 19d output, for example, “96 pulses” as detecting both rising and falling of the pulse per one rotation of the tire.

As shown in FIG. 2, the acceleration sensor 10 detects a gravity component Gr in the axle direction (tire radial direction) with respect to the gravity G as the gravity applied to the tire air pressure detector 4. If the gravitational force Gr is known, the rotation angle made by the acceleration sensor 10 with respect to the reference line Lk passing through the center of the tire 2 (axle 18) can be known. The rotation angle is obtained by the equation cos ⁻¹ (Gr / G).

  As shown in FIG. 1, the controller 6 of the tire pressure detectors 4 a to 4 d is provided with a traveling state determination unit 21 that determines the traveling state of the vehicle 1 based on the gravitational component force Gr input from the acceleration sensor 10. Yes. The traveling state determination unit 21 is based on the amount of change in the gravity component Gr. The traveling state of the vehicle 1 (for example, whether or not traveling, traveling speed, traveling above a certain speed, traveling below a certain speed, just before stopping, stopping, etc.) Determine.

  The controller 6 has either an operation mode of the tire pressure detectors 4a to 4d, an air pressure determination mode for determining an abnormal air pressure of the tires 2a to 2d, or an auto location determination mode for determining an attachment position of each tire 2a to 2d. An operation mode switching unit 22 is set. When the vehicle 1 is decelerated and the vehicle speed V is equal to or lower than the threshold value Vmin (the vehicle speed V becomes low) in the air pressure determination mode, the operation mode switching unit 22 keeps the operation modes of the tire air pressure detectors 4a to 4d constant. Set the time and auto location judgment mode. The operation mode switching unit 22 sets the operation mode of the tire air pressure detectors 4a to 4d to the tire air pressure determination mode after a predetermined time when it is assumed that the tire position determination has been completed in the auto location determination mode.

  The tire pressure detectors 4a to 4d wirelessly transmit the tire pressure signal Stp described above when the tire pressure detectors 4a to 4d are in the air pressure determination mode. The tire pressure signal Stp includes at least the tire pressure, temperature, and tire ID. The tire pressure detectors 4a to 4d transmit an auto location signal Sal necessary for specifying the positions of the tires 2a to 2d when the tire pressure detectors 4a to 4d are in the auto location determination mode. The auto location signal Sal includes, for example, gravity component data, tire ID, and the like. The auto location signal Sal is an example of radio waves used for tire position determination.

  The autolocation function unit 20 includes an axle rotation speed acquisition unit 23 that acquires the number of pulses of the pulse signal Spl output from the axle rotation speed detection sensors 19a to 19d, that is, the axle rotation speed N of each of the axles 18a to 18d. In the autolocation signal Sal received from the tire pressure detectors 4a to 4d, a gravity component acquisition unit 24 that acquires the gravity component Gr included in the autolocation signal Sal is provided.

  The auto-location function unit 20 includes the tires 2a to 2 based on the axle rotational speed N acquired from the axle rotational speed detection sensors 19a to 19d and the gravitational force component Gr acquired from the tire pressure detectors 4a to 4d. A tire position specifying unit 25 that specifies the mounting position of 2d is provided. The tire position specifying unit 25 determines the rotation angle in accordance with the axle rotation speed N based on the axle rotation speed N1 at the first parking and the axle rotation speed N2 at the second parking. (Axle rotation angle) θa is calculated, and the rotation angle (detector) based on the gravity component Gr2 based on the gravity component Gr1 at the first parking and the gravity component Gr2 at the second parking (Rotation angle) θb is calculated. The tire position specifying unit 25 specifies the mounting positions of the tires 2a to 2d by comparing the axle rotation angle θa and the detector rotation angle θb.

  FIG. 3 illustrates an example of the axle rotation angle θa. The axle rotation angle θa corresponds to the rotation angle taken by the axle 18 when the vehicle stops for the second time, based on the rotation position taken by the axle 18 when the vehicle stops for the first time. By the way, since the vehicle 1 travels on a curve, for example, the tires 2a to 2d are configured to rotate independently. For this reason, since the axles 18a to 18d have different rotational speeds, the output pulses of the axle rotational speed detection sensors 19a to 19d also take individual pulse numbers corresponding to the tire positions. Therefore, if the axle rotation angle θa obtained for each of the axles 18a to 18d is confirmed, it can be understood how much each of the four axles 18a to 18d on the front, rear, left and right has rotated from the first stop to the second stop.

FIG. 4 illustrates an example of the detector rotation angle θb. For example, the tire position specifying unit 25 rotates the tire air pressure detector 4 with respect to the reference line Lk at the first stop by substituting the gravity component force Gr1 at the first stop into the equation cos ⁻¹ (Gr1 / G). The position θ1 is calculated. Similarly, the tire position specifying unit 25 substitutes the gravitational component force Gr2 at the time of the second stop into the expression cos ⁻¹ (Gr2 / G) to thereby detect the tire pressure with respect to the reference line Lk at the time of the second stop. 4 is calculated. The tire position specifying unit 25 calculates the detector rotation angle θb by taking the sum of the rotation positions θ1 and θ2.

  On the side of the tire pressure detectors 4a to 4d, the controller 6 has a rotation position θ1 of the tire pressure detectors 4a to 4d at the first stop and a rotation position θ2 of the tire pressure detectors 4a to 4d at the second stop. A detector rotation angle calculation unit 26 for calculating an angle formed, that is, a detector rotation angle θb is provided. The detector rotation angle calculation unit 26 calculates the detector rotation angle θb by the same method as the tire position specifying unit 25 described above, and obtains the respective detector rotation angles θb of the tire pressure detectors 4a to 4d. The detector rotation angle calculation unit 26 is an example of radio wave transmission timing.

  The controller 6 is provided with a delay time setting unit 27 for setting a delay time when the auto location signal Sal is transmitted. The delay time setting unit 27 sets a delay time corresponding to the detector rotation angle θb based on the detector rotation angle θb calculated by the detector rotation angle calculation unit 26. The delay time is set so that the radio wave transmission intervals of the tire pressure detectors 4a to 4d are relatively prime or approximately prime. The tire pressure detectors 4 a to 4 d wirelessly transmit the auto location signal Sal at a timing reflecting the delay time set by the delay time setting unit 27. The delay time setting unit 27 is an example of a radio wave transmission timing setting unit.

Next, operation | movement of the tire position determination system 17 of this example is demonstrated using FIGS.
[Air pressure judgment mode operation]
FIG. 5 is an image diagram of the operation of the tire pressure detector 4. In FIG. 5, the transmission timing of radio waves and the sampling timing of gravity are shown in the graph, but the timing is schematically shown because the drawing is schematic. Since it is necessary to detect an abnormal air pressure of the tires 2a to 2d during normal running and stopping, the operation mode switching unit 22 sets the operation mode of the tire air pressure detectors 4a to 4d to the air pressure determination mode. For example, when the stopped vehicle 1 starts to travel, the tires 2a to 2d that have been stopped until then start rotating, so that the gravity component Gr changes. At this time, the traveling state determination unit 21 determines that the vehicle speed V is “low speed (traveling less than a constant speed)” when the change amount of the gravity component Gr is less than the threshold, and the change of the gravity component Gr. When the amount is equal to or greater than the threshold value, it is determined that the vehicle speed V is “running (running above a certain speed)” of Vmin or higher.

  FIG. 6 shows specific operation contents of the tire pressure detectors 4a to 4d in the air pressure determination mode. In the air pressure determination mode, the periodic radio wave transmission (transmission of the tire air pressure signal Stp) during traveling is set to 1 time / minute, and the periodic radio wave transmission (transmission of the tire air pressure signal Stp) during non-running is performed once. / 5 minutes are set. Here, “non-running” includes parking and stopping and low speed. In addition, the air pressure measurement is performed every periodic radio wave transmission, the temperature measurement is performed every periodic radio wave transmission, and the gravity measurement is performed once every 10 seconds.

  As shown in FIG. 5, in the air pressure determination mode, the operation mode switching unit 22 sets the periodic radio wave transmission at the time of non-traveling to transmission at intervals of 5 minutes, and the periodic radio wave transmission at the time of travel is transmitted at intervals of 1 minute. Set to. For this reason, both compliance with laws and regulations for completing the notification of air pressure abnormality and ensuring the battery life of the tire pressure detectors 4a to 4d are compatible. In the air pressure determination mode, since it is necessary to periodically know whether the vehicle 1 is running or not running, the gravity measurement for judging running / non-running is performed at a short interval (every 10 seconds). To do. At the time of regular transmission, information necessary for monitoring the tire air pressure, such as the air pressure and temperature of the tires 2a to 2d, is transmitted, so that measurement corresponding to the transmission is also performed.

  When the tire pressure signal Stp transmitted from the tire pressure detectors 4a to 4d is received by the receiving antenna 14, the TPMS receiver 12 collates the tire ID in the tire pressure signal Stp. Check the pressure data in the air pressure signal Stp. At this time, if the pressure value is equal to or lower than the low pressure threshold, the TPMS receiver 12 displays the low pressure tire on the display unit 16 in association with the tire position. The TPMS receiver 12 performs the tire pressure determination for each tire pressure signal Stp received to monitor the tire pressures of the tires 2a to 2d.

[Operation of auto location judgment mode]
As shown in FIG. 5, after the vehicle 1 enters the traveling state, for example, when the vehicle 1 stops by a signal or the like, the vehicle speed V gradually decreases. At this time, since the rotational speeds of the tires 2a to 2d are gradually reduced, the amount of change in the gravitational component force Gr is reduced. When the operation mode switching unit 22 confirms that the amount of change in the gravitational force Gr is less than the threshold value, that is, the vehicle speed V is less than the threshold value Vmin during the air pressure determination mode, the operation mode switching unit 22 determines that the vehicle 1 “shifts to stop”. When the operation mode switching unit 22 determines that the vehicle 1 is to be stopped, the operation mode of the tire pressure detectors 4a to 4d is switched to the auto location determination mode. The state that the vehicle 1 takes after the stoppage transition is “non-stop” just before the stop and “stop” where the vehicle speed V is “0”.

  FIG. 7 shows the specific operation contents of the tire pressure detectors 4a to 4d in the auto-location determination mode. In the auto location determination mode, periodic radio wave transmission (transmission of the auto location signal Sal) when the vehicle is stopped is set to once / 5 seconds. It should be noted that the operation mode returns to the air pressure determination mode after transmitting the auto location signal Sal ten times. Gravity measurement is set once / 20 ms.

  In the auto location determination mode, a timeout (time limit) is set. This is because, in the auto-location determination mode, gravity measurement and radio wave transmission are frequent, so battery consumption in the tire pressure detectors 4a to 4d is intense. From the viewpoint of ensuring the battery life of the tire pressure detectors 4a to 4d, This is because it is preferable to forcibly return the operation mode of the tire air pressure detectors 4a to 4d to the air pressure determination mode after a certain time when the autolocation determination is expected to end. In this example, the time limit is set to 3 minutes.

  As shown in FIG. 5, the operation mode switching unit 22 transmits the autolocation signal Sal by a periodic transmission operation by interruption when the vehicle is not stopped in the autolocation determination mode. For this reason, the autolocation signal Sal is transmitted at a necessary timing when the autolocation determination mode is not stopped. The operation mode switching unit 22 sets periodic radio wave transmission to transmission at intervals of 5 seconds when the vehicle is stopped in the auto location determination mode. In this way, the interval between radio wave transmissions is as short as 5 seconds, because a stop such as waiting for a signal is short in time, so that radio wave transmission is made in time while waiting for a signal. In the auto-location determination mode, a large amount of gravity information is required just before and when the vehicle is stopped, so that the gravity information is acquired at a sufficiently short time interval (20 ms) with respect to the rotation of the tire 2. At the time of regular transmission, the gravitational component force Gr necessary for the auto-location determination of the tires 2a to 2d is necessary, so measurement according to transmission is also performed.

[Operation of tire position judgment by auto location judgment mode]
Next, a specific operation of the tire position determination in the auto location determination mode will be described using the flowchart shown in FIG.

  In step 101, the tire air pressure monitoring ECU 13 determines whether or not the vehicle speed V is less than a threshold value Vmin based on vehicle speed data acquired from, for example, a meter ECU (not shown). That is, it is determined whether or not the vehicle 1 enters the “first stop”. If the vehicle 1 enters the first stop, the process proceeds to step 102. If the vehicle 1 does not enter the first stop, the process waits at step 101.

  On the other hand, in the tire air pressure detectors 4a to 4d, the operation mode switching unit 22 changes the operation mode of the tire air pressure detectors 4a to 4d from the previous air pressure determination mode when the vehicle speed V is less than the threshold value Vmin during deceleration. Switch to auto location determination mode. At this time, gravity measurement is switched to a state in which it is executed once every 20 ms. The traveling state determination unit 21 determines whether the vehicle 1 is “just before stopping” or “stopped” based on the gravitational force Gr acquired at a measurement interval of 20 ms. The traveling state determination unit 21 determines “just before stopping” when a difference occurs before and after the measured gravity component Gr, and determines “stop” when there is no difference before and after the measured gravity component Gr.

  If the vehicle 1 is about to stop, the operation mode switching unit 22 sets periodic radio wave transmission to a transmission operation by interrupt processing. Moreover, if the vehicle 1 is stopped, the operation mode switching unit 22 sets periodic radio wave transmission to transmission at intervals of 5 seconds. For this reason, the tire pressure detectors 4a to 4d transmit the auto location signal Sal at the execution timing of the radio wave transmission interruption if the vehicle 1 is about to stop, and as short as 5 seconds if the vehicle 1 is stopped. An auto location signal Sal is transmitted at a transmission interval. The auto location signal Sal is a signal including, for example, tire ID, gravity force data measured at the time of interruption radio wave transmission, and the like.

  When the vehicle 1 stops (first stop), the detector rotation angle calculation unit 26 rotates the tire pressure detectors 4a to 4d at the first stop based on the gravity component Gr1 at this time. The position θ1 is calculated. The detector rotation angle calculation unit 26 temporarily stores the calculated rotation position θ1 in the memory 7.

  In step 102, the tire pressure monitoring ECU 13 receives the autolocation signal Sal transmitted from the tire pressure detectors 4a to 4d of the own vehicle by the receiving antenna 14 at the first stop. That is, the gravitational component force acquisition unit 24 reads the gravity component data of the autolocation signal Sal transmitted from the tire air pressure detectors 4a to 4d at the first stop, so that each tire air pressure detector 4a at the first stop is obtained. Collect ~ 4d gravity component Gr1.

  In step 103, the gravitational component force acquisition unit 24 determines whether or not the gravitational component force Gr1 at the first stop has been acquired from all the tire air pressure detectors 4a to 4d within a predetermined time. At this time, if the gravitational component force Gr1 at the time of the first stop can be acquired from all the tire pressure detectors 4a to 4d within a certain time, the routine proceeds to step 104. By the way, there is a possibility that the tire pressure detectors 4a to 4d are located at the null point during the stop depending on the tire rotation position at that time. For this reason, waiting for radio wave reception for a certain period of time, if radio waves for four wheels cannot be received even after waiting for a certain period of time, the process returns to step 101 to acquire radio waves at another stop timing.

  In step 104, the axle rotational speed acquisition unit 23 clears the counters 28 of the axle rotational speed detection sensors 19a to 19d of the axles 18a to 18d. That is, the axle rotation speed acquisition unit 23 starts counting each pulse output from the axle rotation speed detection sensors 19a to 19d when the vehicle 1 starts running after the first stop.

  In step 105, the gravitational component force acquisition unit 24 uses the gravitational component force data of the tire pressure detectors 4a to 4d acquired in step 102 as the gravity component force Gr1 of the tire pressure detectors 4a to 4d at the first stop. Is temporarily stored in the memory 15.

  On the other hand, in the tire pressure detectors 4a to 4d, the operation mode switching unit 22 transmits the autolocation signal Sal a predetermined number of times (for example, 10 times) in the autolocation determination mode or when the autolocation determination mode times out. The operation mode of the tire pressure detectors 4a to 4d is returned to the air pressure determination mode. As a result, the tire pressure detectors 4a to 4d return to the state of performing the air pressure measurement, the temperature measurement, and the gravity measurement at the timing set in the air pressure determination mode, and the tire pressure at the periodic radio wave transmission timing set in the air pressure determination mode. A signal Stp is wirelessly transmitted to the vehicle body 5. The TPMS receiver 12 grasps the tire pressure of each of the tires 2a to 2d from the received tire pressure signal Stp, and if the air pressure is equal to or lower than the low pressure threshold, notifies the low pressure tire on the display unit 16.

  In step 106, the tire air pressure monitoring ECU 13 determines whether or not the vehicle speed V has become less than the threshold value Vmin after the vehicle 1 has traveled a certain distance based on the vehicle speed data acquired from the meter ECU or the like. That is, it is determined whether or not the vehicle 1 has entered the “second stop”. If the vehicle 1 enters the second stop, the process proceeds to step 107. If the vehicle 1 does not enter the second stop, the process waits at step 106.

  As in the first stop, the operation mode switching unit 22 changes the operation mode of the tire air pressure detectors 4a to 4d from the previous air pressure determination mode to auto-location when the vehicle speed V is less than the threshold value Vmin during deceleration. Switch to judgment mode. Therefore, the tire pressure detectors 4a to 4d operate at radio wave transmission intervals and measurement intervals that conform to the autolocation determination mode, and wirelessly transmit the autolocation signal Sal to the vehicle body 5.

  When the vehicle 1 stops (second stop), the detector rotation angle calculation unit 26 rotates the tire pressure detectors 4a to 4d at the second stop based on the gravity component Gr2 at this time. The position θ2 is calculated. The detector rotation angle calculation unit 26 adds the rotation position θ1 stored in the memory 7 and the calculated rotation position θ2 to detect each tire air pressure at the first stop and at the second stop. The angle formed by the devices 4a to 4d, that is, the detector rotation angle θb is calculated in each of the tire pressure detectors 4a to 4d. The delay time setting unit 27 sets a delay time corresponding to each θb based on each detector rotation angle θb calculated by the detector rotation angle calculation unit 26.

  FIG. 9 shows an example of setting the delay time. For example, when the detector rotation angle θb of the right front tire pressure detector 4a is 10 degrees, the radio wave transmission delay time of the right front tire pressure detector 4a is set to 10 ms. When the detector rotation angle θb of the right rear tire pressure detector 4c is 25 degrees, the radio wave transmission delay time of the right rear tire pressure detector 4c is set to 25 ms. When the detector rotation angle θb of the left front tire pressure detector 4b is 125 degrees, the radio wave transmission delay time of the left front tire pressure detector 4b is set to 125 degrees. When the detector rotation angle θb of the left rear tire pressure detector 4d is 90 degrees, the radio wave transmission delay time of the left rear tire pressure detector 4d is set to 90 degrees.

  Each tire pressure detector 4a to 4d transmits the auto location signal Sal after delaying the transmission timing by the delay time set by the delay time setting unit 27. For example, when the basic period of transmission of the auto location signal Sal is 5 seconds as in this example, the right front tire pressure detector 4a transmits radio waves at a transmission interval of 5.01 s, and the right rear tire pressure detector 4c is 5.025 s. The left front tire pressure detector 4b transmits a radio wave at a transmission interval of 5.125 s, and the left rear tire pressure detector 4d transmits a radio wave at a transmission interval of 5.09 s.

  In step 107 shown in FIG. 8, the tire pressure monitoring ECU 13 receives the autolocation signal Sal transmitted from the tire pressure detectors 4 a to 4 d of the own vehicle by the receiving antenna 14 at the second stop. That is, the gravitational component force acquisition unit 24 reads the gravity component data of the autolocation signal Sal transmitted from the tire air pressure detectors 4a to 4d at the second stop, so that each tire air pressure detector 4a at the second stop is obtained. Collect ~ 4d gravity force Gr2.

  In step 108, the gravitational component force acquisition unit 24 determines whether or not the gravitational component force Gr2 at the second stop has been acquired from all the tire air pressure detectors 4a to 4d within a predetermined time. At this time, if the gravitational component force Gr2 at the time of the second stop can be acquired from the all tire pressure detectors 4a to 4d within a certain time, the process proceeds to step 109, and the second time from all the tire pressure detectors 4a to 4d within a certain time If the gravitational force Gr2 at the time of stopping cannot be acquired, the process is forcibly terminated. Here, the reason for waiting for radio wave reception for a certain period of time is the same reason as in Step 103. If all gravitational force components Gr2 cannot be obtained within a certain period of time, the process is forcibly terminated and processed at another opportunity. Is executed again.

  In step 109, the tire position specifying unit 25 divides the pulses (measured pulse numbers) measured by the counters 28 of the axle rotation speed detection sensors 19a to 19d by the total number of pulses input per tire rotation. The remainder of the value is obtained, and the axle rotation angle θa of each axle rotation speed detection sensor 19a to 19d is calculated.

  In step 110, the tire position specifying unit 25 determines the tire pressure detectors 4a to 4 based on the gravitational component forces Gr1 and Gr2 acquired from the tire pressure detectors 4a to 4d at the first stop and the second stop, respectively. 4d detector rotation angle θb is calculated.

  FIGS. 10A to 10C are views showing the movement when the tire 2 rotates clockwise in the drawing, and FIGS. 11A to 11C show the tire 2 rotating counterclockwise in the drawing. It is the figure which showed the movement when doing. When calculating the detector rotation angle θb, the gravity component force Gr is the same in the state of FIG. 10C and the state of FIG. 11C which are symmetrical with respect to the reference line Lk passing through the center of the tire 2. Therefore, when the rotational position of the tire pressure detector 4 is specified, it is necessary to distinguish these gravitational force components Gr.

  In this case, the state shown in FIG. 10 (c) and the state shown in FIG. 11 (c) are distinguished by checking whether the change in the gravity component Gr when the tire 2 is about to stop is increased or decreased. It is possible. Therefore, in the case of this example, when the vehicle is about to stop, the gravitational force measurement is performed at an early interval (every 20 ms), thereby acquiring a large number of gravitational force components Gr necessary for determination of increase or decrease. When the tire rotation moves from FIG. 10B to FIG. 10C, the gravitational force Gr monotonously decreases. On the other hand, when the tire rotation moves from FIG. 11B to FIG. 11C, the gravitational force Gr monotonously increases. Therefore, the tire position specifying unit 25 distinguishes the gravity force Gr at the left-right symmetrical position by confirming the change in the gravity force Gr when the tire 2 is about to stop.

  In step 111 shown in FIG. 8, the tire position specifying unit 25 uses the axle rotation angle θa obtained in step 109 and the detector rotation angle θb obtained in step 110 to specify the mounting positions of the tires 2a to 2d. To do. For example, the tire position specifying unit 25 specifies the mounting position of the tires 2a to 2d, that is, the relationship between the tire ID and the tire position, by checking which axle rotation angle θa the detector rotation angle θb matches. At this time, if the axle rotation angle θa and the detector rotation angle θb have a one-to-one correspondence, the mounting positions of all four wheels are specified.

  In step 112, the tire position specifying unit 25 determines whether or not the positions of all the tires 2a to 2d have been specified within a certain time. At this time, if the mounting positions of all the tires 2a to 2d can be specified within a certain time, the process proceeds to step 113. If the mounting positions of all the tires 2a to 2d cannot be specified within a certain time, the process is forcibly terminated.

  In step 113, the tire position specifying unit 25 registers the tire position specifying result in the memory 15 of the tire pressure monitoring ECU 13. That is, the tire position specifying unit 25 stores in the memory 15 which tire ID is the tire 2a to 2d of the front, rear, left and right four wheels. Thus, the auto location of the tires 2a to 2d is completed. This auto location function is repeatedly executed, for example, in a predetermined cycle.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) The tire pressure detectors 4a to 4d each calculate the detector rotation angle θb based on the gravitational component force Gr detected by the acceleration sensor 10, and set a delay time corresponding to each detector rotation angle θb. . Each tire pressure detector 4a to 4d transmits an autolocation signal Sal after reflecting its own delay time at the time of autolocation determination. Therefore, since the autolocation signal Sal transmitted from the tire pressure detectors 4a to 4d is less likely to collide at the time of the autolocation determination, the establishment of communication can be ensured.

  (2) Collision avoidance of the auto location signal Sal is realized by setting a delay time to the timing of radio wave transmission when the auto location signal Sal is received from each tire pressure detector 4a-4d. Therefore, the radio wave transmission timings of the tire pressure detectors 4a to 4d can be made different by a simple method of setting the delay time.

  (3) The tire pressure detectors 4a to 4d can be switched to an auto location determination mode for determining a tire position in addition to an air pressure determination mode for monitoring the tire pressure. Therefore, since the tire pressure detectors 4a to 4d can be operated in a mode suitable for the tire position determination at the time of auto-location determination, the tire position determination can be completed by an optimal operation mode.

  (4) When the vehicle speed V decelerates below the threshold value Vmin, the operation mode of the tire air pressure detectors 4a to 4d is switched to an auto location determination mode suitable for performing tire position determination. Therefore, the tire position determination performed when the vehicle is decelerated can be accurately performed.

  (5) The radio wave transmission interval in the auto location determination mode is set shorter than in the air pressure determination mode. For this reason, even if the stop time is short, such as waiting for a signal, the transmission of the auto location signal Sal can be made in time during the stop. Therefore, the auto location determination can be completed quickly in a short time.

Note that the embodiment is not limited to the configuration described so far, and may be modified as follows.
The radio wave transmitted by the tire pressure detector 4 in the auto-location determination mode is not limited to the dedicated auto-location signal Sal, and may be, for example, a signal in which gravity information is placed on a normal tire pressure signal Stp.

-When the vehicle stops, the number of frames may be temporarily increased to transmit the auto location signal Sal.
The tire pressure detector 4 may immediately transmit the auto location signal Sal when it is determined that the vehicle is stopped.

  The acceleration sensor 10 is not limited to a sensor that detects the gravitational force component Gr in the axle direction, and may be a sensor that can detect only the gravitational force force in a direction orthogonal to the axle direction, or the axle direction and its orthogonal direction, for example. A two-axis type sensor capable of detecting both gravitational force components may be used.

  The detector rotation angle θb is not limited to a value calculated by taking the sum of θ1 and θ2. For example, the tire position may be determined by extracting all the possible angles of the detector rotation angle θb in the range of 0 ° to 360 ° and checking which one matches the axle rotation angle θa.

The gravity component detection unit is not limited to the acceleration sensor 10 and may be any sensor that can detect the gravity component applied to the tire air pressure detector 4.
The axle rotation speed detection unit is not limited to the ABS sensor, and can be changed to another sensor as long as it can detect the rotation speed (rotation amount) of the axle 18.

-Tire pressure measurement and temperature measurement are not limited to each periodic radio wave transmission, and may be performed multiple times as necessary.
The determination of whether the tire pressure detector 4 is located on the left or right side with respect to the reference line Lk may be performed on the tire pressure detector 4 side.

  The travel / non-run determination threshold in the air pressure determination mode and the stop / non-stop determination threshold in the auto location determination mode are not limited to using the same threshold Vmin, and may be different values.

The radio wave periodically transmitted from the tire pressure detector 4 may have a different frame content or may be the same in each mode.
-In auto location determination mode, it is possible to return to air pressure determination mode by interrupt processing.

The collection of the gravitational force Gr is not limited to being performed when the vehicle is stopped, and may be performed, for example, when parking.
The tire pressure detector 4 may shift to an auto location determination mode when the vehicle is stopped.

Auto-location determination may include spare tires.
The automatic location determination is not limited to being performed when the vehicle is stopped, and may be performed when the vehicle 1 is started, for example. In this case, since it is not necessary to consider the reverse rotation of the tire 2 that is assumed to occur when the vehicle is stopped, the effect of ensuring the accuracy of specifying the tire position is high.

The auto location determination is not limited to being performed when the vehicle is stopped or parked, and may be performed at a low speed that can be regarded as a stop, for example.
The tire pressure detector 4 is not limited to being able to switch between two modes, an air pressure determination mode and an auto location determination mode. For example, an operation corresponding to the air pressure determination mode may be taken at all times, and the gravitational force data may be put on the transmitted tire air pressure signal Stp every time.

  The method for not synchronizing the transmission timing of the auto location signal Sal is not limited to the method for setting the delay time. For example, it is possible to change to various modes such as increasing the radio wave transmission interval in order of increasing detector rotation angle θb.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) In the tire position determination system, the auto-location function unit measures the number of pulses of the pulse signal input from the axle rotation speed detection unit between the time of the first stop and the time of the second stop. The axle rotation angle is calculated based on the remainder obtained by dividing the number of measurement pulses by the total number of pulses input per tire rotation.

  (B) In the tire position determination system, the auto-location function unit is based on the gravitational component force acquired at the time of the first stop, at the time of the first stop with respect to a vertical reference line passing through the center of the tire. A first rotation position taken by the tire pressure detector is obtained, and similarly, a second rotation position taken by the tire pressure detector at the time of the second stop is obtained, and based on the first rotation position and the second rotation position. Calculating the detector rotation angle;

  (C) A function of a tire pressure monitoring system that transmits a tire pressure signal from a tire pressure detector attached to each tire and receives the tire pressure signal at a receiver of the vehicle body to monitor the tire pressure. In the tire position determination system for determining the position of the tire from the position of the tire air pressure detector, the axle rotation speed detected by the axle rotation speed detection unit at the first start and the axle rotation speed detection unit at the second start The axle rotation angle calculated from the determined axle rotation speed, the gravitational force generated in the tire air pressure detector at the first start, and the gravitational force generated in the tire air pressure detector at the second start The auto-location function unit that determines the tire position based on the detector rotation angle calculated from the The radio transmission timing of the necessary that it is the detector tire position determination system having a radio transmission timing setting unit for setting in accordance with the rotation angle.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 (2a-2d) ... Tire, 3 ... Tire pressure monitoring system, 4 (4a-4d) ... Tire pressure detector, 5 ... Vehicle body, 10 ... Acceleration sensor as gravity force detection part, 12 ... Receiver (TPMS receiver), 17 ... Tire position determination system, 19 (19a to 19d) ... Axle rotation speed detection sensor as an axle rotation speed detection unit, 20 ... Auto location function unit, 21 ... Running state determination unit, 22 ... operation mode switching part, 26 ... detector rotation angle calculation part constituting radio wave transmission timing setting part, 27 ... delay time setting part constituting radio wave transmission timing setting part, Stp ... tire pressure signal, N (N1, N2) ... axle rotation speed, Gr (Gr1, Gr2) ... gravity force, θa ... axle rotation angle, θb ... detector rotation angle, V ... vehicle speed, Vmin ... threshold.

Claims (6)

This is a function of a tire pressure monitoring system that transmits a tire pressure signal from a tire pressure detector attached to each tire, receives the tire pressure signal at a receiver of a vehicle body, and monitors the tire pressure. In the tire position determination system for determining the position of the tire from the position of the air pressure detector,
The axle rotation angle calculated from the axle rotation speed detected by the axle rotation speed detection unit at the time of the first stop and the axle rotation speed detected by the axle rotation speed detection unit at the time of the second stop, and the above-mentioned at the time of the first stop Auto that determines the position of the tire based on the rotation angle of the detector calculated from the gravity force generated in the tire pressure detector and the gravity force generated in the tire pressure detector during the second stop With a location function
Tire position determination, comprising: a radio wave transmission timing setting unit that sets a transmission timing for transmitting a radio wave used for tire position determination from the tire pressure detector according to the detector rotation angle system. The radio wave transmission timing setting unit shifts the transmission timing of radio waves transmitted from each tire pressure detector by setting a delay time according to the detector rotation angle. Tire position determination system. The tire pressure detector is
A traveling state determination unit that determines a traveling state of the vehicle using a detection signal of the gravity component detection unit capable of detecting the gravity component force;
The tire position determination system according to claim 1, further comprising an operation mode switching unit that switches an operation mode of the tire pressure detector based on a determination result of the traveling state determination unit. The operation mode switching unit determines the position of the tire from an operation mode of the tire air pressure detector and an air pressure determination mode for monitoring the air pressure of the tire when the vehicle speed of the running vehicle decelerates below a threshold value. Set to auto location judgment mode,
The tire position determination system according to claim 3, wherein the radio wave transmission timing setting unit sets the transmission timing of the radio wave in the auto location determination mode. In the auto location determination mode, the interval between periodic radio wave transmissions is set to be shorter than in the air pressure determination mode,
5. The tire position determination system according to claim 4, wherein the tire pressure detector transmits the gravitational force to the vehicle body at a short transmission interval in the auto-location determination mode. 6. The delay time is set to a value that is relatively prime in each tire pressure detector, or a value in which the least common multiple does not exceed the stop time. 6. Tire position determination system.