JP2008168674A - Tire air pressure detecting apparatus and tire air pressure detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire air pressure detecting apparatus capable of easily performing the management of air pressure in each of the tires with a simple configuration. <P>SOLUTION: A receiver 28 on a vehicle 10 is arranged on each of different positions differing to each other from each of the wheels 14. TPMS-ECU 30 estimates on what wheel 14 a transmitter 26 arranged on an optional one wheel is arranged in response to a receiving intensity of a signal received by the receiver 28. Then, TPMS-ECU 30 gets pressure information of a tire of the wheel to be estimated on the basis of pressure information got from the reference wheel having the transmitter 26 arranged therein, dynamic state information based on a wheel speed and a dynamic state information of the tire of the wheel to be estimated and outputs pressure information of each of the tires. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tire pressure acquisition device and a tire pressure acquisition method, and more particularly to an improvement in a tire pressure acquisition device and a tire pressure acquisition method that can easily manage the pressure of each tire with a simple configuration.

  When the pressure of the tire mounted on the vehicle is lower than the recommended pressure, the behavior of the vehicle may become unstable, and the braking performance, fuel consumption, and tire life may be reduced. Therefore, various techniques for monitoring the air pressure of each tire have been proposed. By acquiring the individual tire pressure state, it is possible to predict a decrease in tire reliability, a tire replacement time, a tire rotation time, and the like, which can contribute to an improvement in tire reliability.

As a technology to know the tire pressure of each tire, TPMS (Tire Pressure Monitoring System) which arranges the air pressure sensor and the transmitter in each tire and the receiver that receives the information transmitted from the transmitter on the vehicle side. is there. An ID which is identification information is assigned in advance to a transmitter provided in each tire. On the vehicle body side, based on the ID transmitted together with the air pressure information, it is determined whether the received air pressure information is information on the left front wheel, information on the right front wheel, information on the left rear wheel, or information on the right rear wheel. The accuracy of the value drop determination is improved. Moreover, the tire pressure alarm device disclosed in Patent Document 1 includes a pressure sensor air pressure transmitter on at least one of the three wheels. In the tire air pressure alarm device, the air pressure of the wheel provided with the air pressure transmitting unit can be reliably detected. Moreover, the wheel speed of the wheel provided with the air pressure transmission unit is set as the reference wheel speed, and the decrease in the tire air of the other wheels is detected from the change in the wheel speed ratio of the wheel speeds of the other wheels to the reference wheel speed. .
JP-A-7-52621

  However, in the conventional apparatus, an ID is assigned to each transmitter in order to determine from which tire transmitter the pneumatic pressure information received by the vehicle-side receiver is transmitted. The ID indicates a tire mounting position with respect to the vehicle, and the relationship between the ID of each tire and the tire mounting position needs to be correctly associated when the vehicle is shipped from the factory. If this association is not performed accurately, it is not possible to identify a tire whose air pressure has decreased, and the tire pressure cannot be sufficiently managed. Such ID association leads to an increase in man-hours at the time of vehicle shipment. In addition, when the tire is rotated by the dealer or the user after the vehicle is shipped, the ID and the tire mounting position do not coincide with each other, so that the ID registration needs to be performed again. This re-registration work is a heavy work load and has been one of the causes of neglecting the management of tire pressure.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a tire pressure acquisition device and a tire pressure acquisition method capable of easily managing the pressure of each tire with a simple configuration. .

  In order to solve the above-described problem, a tire air pressure acquisition device according to an aspect of the present invention includes an air pressure sensor that acquires pressure information inside a tire using any at least one of a plurality of wheels mounted on a vehicle as a reference wheel. A transmitter that is disposed on the reference wheel and transmits a signal including pressure information acquired by the air pressure sensor to the vehicle side, and a receiver that receives a signal from the transmitter, and is mounted on the vehicle A receiver arranged at a position on the vehicle such that the distance from each wheel is different; and a reference wheel position estimating means for estimating a mounting position of the reference wheel based on a received intensity of a signal received by the receiver; Wheel state information acquisition means for acquiring dynamic state information based on wheel speed for each of the plurality of wheels, and pressure information of the reference wheel and a wheel at the estimated mounting position. Based on the acquired dynamic state information and the dynamic state information acquired on the estimation target wheels other than the reference wheel, pressure estimation means for estimating the pressure information of the estimation target wheel, and an output for outputting a result including the pressure information Means.

  The air pressure sensor and the transmitter are arranged on any at least one wheel as a set. On the other hand, the receiver is arranged at a position where the distance from each wheel mounted on the vehicle is different. For example, when the receiver is arranged near the left rear wheel, the wheel closest to the receiver is the left rear wheel. The next closest wheel is the right rear wheel, the next closest wheel is the left front wheel, and the farthest wheel is the right front wheel. That is, when the transmitter is disposed on the left rear wheel, the signal received by the receiver is relatively strongest. On the other hand, when the transmitter is arranged on the right front wheel, the signal received by the receiver is relatively weakest. Similarly, when the transmitter is disposed on the right rear wheel, the second highest reception strength is obtained, and when the transmitter is disposed on the left front wheel, the third highest reception strength is obtained. For example, when the receiver is arranged near the left rear wheel, if the transmitter receives a range of received intensity received by the receiver when the transmitter is arranged on each wheel, the receiver The position where the transmitter is arranged can be estimated based on the received intensity of the received signal.

  By the way, when the tire air pressure changes, the tire diameter changes. For example, when the air pressure decreases, the tire diameter decreases in proportion to the amount of decrease. In this case, if the vehicle is traveling straight, a tire having a reduced air pressure rotates faster than a tire having no air pressure. That is, the dynamic state information related to the wheel speed changes according to the change in tire air pressure. Therefore, if the pressure information of the reference wheel on which the transmitter is arranged, the movement state information of the wheel at the mounting position estimated as the position of the reference wheel, and the movement state information of the estimation target wheel are known, the pressure information of the estimation target wheel Can be estimated. In this case, even if the wheel is arbitrarily rotated, the reference wheel position information, pressure information, and dynamic state information are acquired each time. The wheel information can be estimated.

  In the above aspect, the output unit may output the position information of the wheel mounted on the vehicle and the pressure information in association with each other. The pressure information can be, for example, information indicating that the air pressure is lower than the reference value. According to this aspect, it is possible to identify and notify the user of the wheel in which the tire air pressure has decreased.

  In the above aspect, the output means may output a tire air pressure value of the wheel estimated from the pressure information. According to this aspect, it is possible to estimate the air pressure value of a tire on which no air pressure sensor is arranged based on the detection value of the air pressure sensor arranged on any one wheel.

  In the above aspect, the output means may output an alarm when a tire air pressure value based on the pressure information is a predetermined value or less. According to this aspect, the tire air pressure abnormality can be promptly presented to the user.

  In order to solve the above-described problem, a tire pressure acquisition method according to an aspect of the present invention provides a signal including tire pressure information from each wheel, using any at least one of a plurality of wheels mounted on a vehicle as a reference wheel. Transmitting to a receiver disposed at a position on the vehicle such that the distances of the reference wheels are different from each other, and estimating a mounting position of the reference wheel on the vehicle based on a reception intensity of a signal received by the receiver; , A step of acquiring dynamic state information based on wheel speed for each of the plurality of wheels, pressure information of the reference wheel and dynamic state information acquired for a wheel at the estimated mounting position, and other than the reference wheel Based on the dynamic state information acquired at the estimation target wheel, estimating the pressure information of the estimation target wheel, and outputting the result including the pressure information; Characterized in that it contains.

  According to this aspect, the position of the reference wheel can be estimated based on the reception intensity of the signal received from the transmitter disposed on the reference wheel that is an arbitrary one of the plurality of wheels. Moreover, pressure information other than the reference wheel can be estimated based on the pressure information and dynamic state information acquired by the reference wheel and the dynamic state information of each wheel.

  According to the tire pressure acquisition device and the tire pressure acquisition method of the present invention, it is possible to easily manage the pressure of each tire with a simple configuration.

  Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

  The tire pressure acquisition device and the tire pressure acquisition method of the present embodiment can manage the tire pressure equivalent to the conventional TPMS using ID for wheel identification. By positioning the receiver on the vehicle at a position where the distance from each wheel is different, it is estimated which position the transmitted signal is transmitted from the transmitter of the wheel. And based on the pressure information acquired from the wheel where the transmitter is arranged, the dynamic state information based on the wheel speed, and the dynamic state information of the estimation target wheel, the pressure information of the tire of the estimation target wheel is obtained. get. That is, the pressure information of the tires of all the wheels is acquired for each wheel based on the pressure information acquired from one wheel.

  FIG. 1 is a conceptual explanatory diagram of a vehicle 10 including a tire air pressure acquisition device according to the present embodiment.

  The vehicle 10 includes a vehicle body 12, a right front wheel 14a provided on the right front (FR) of the vehicle body 12, a left front wheel 14b provided on the left front (FL) of the vehicle body 12, and a right rear (RR) of the vehicle body 12. A right rear wheel 14c and a left rear wheel 14d provided on the left rear (RL) of the vehicle body 12 are provided. Hereinafter, the right front wheel 14a, the left front wheel 14b, the right rear wheel 14c, and the left rear wheel 14d may be collectively referred to as “wheels 14” as necessary. Moreover, it may only call the wheels 14a, 14b, 14c, and 14d. In addition, in this embodiment, a wheel shall mean what combined the tire part and the wheel part.

  A front right wheel speed sensor 16a is disposed at a position on the vehicle body 12 side facing the right front wheel 14a. Similarly, a left front wheel speed sensor 16b is positioned at a position facing the left front wheel 14b, a right rear wheel speed sensor 16c is positioned at a position facing the right rear wheel 14c, and a left rear wheel speed sensor is positioned at a position facing the left rear wheel 14d. 16d is arranged to detect the wheel speed of each wheel 14 during traveling. The right front wheel speed sensor 16a, the left front wheel speed sensor 16b, the right rear wheel speed sensor 16c, and the left rear wheel speed sensor 16d may be collectively referred to as “wheel speed sensor 16”. Further, it may be simply referred to as wheel speed sensors 16a, 16b, 16c, and 16d. As the wheel speed sensors 16a to 16d, known sensors can be used, and the number of passing teeth of the serration attached to the wheel is detected by a magnetic pickup type or Hall IC type sensor to detect the wheel speed. Each detected wheel speed is provided to an ABS-ECU 18 that controls an anti-lock brake system (ABS). The ABS monitors the rotational state of the wheels 14a to 14d and prevents the braking force of the brake devices of each wheel 14 individually in order to prevent the wheels 14 from locking when braking suddenly or when the brake is applied on a slippery road surface. Control. The ABS-ECU 18 is not shown in addition to the steering sensor 22 that detects the turning angle of the steering wheel 20, but information acquired by a sensor that detects the behavior of the vehicle 10, such as a lateral G sensor or a yaw rate sensor. Is provided.

  The vehicle 10 of the present embodiment includes a pneumatic sensor 24 that detects tire air pressure (pressure information) on any one of the four wheels 14 that are mounted, and pressure information detected by the air pressure sensor 24 based on the pressure information detected by the vehicle body 12. A transmitter 26 for transmitting to the side is arranged. In the present embodiment, the wheel 14 on which the air pressure sensor 24 and the transmitter 26 are arranged is referred to as a reference wheel, and the other wheels are referred to as estimation target wheels. In the case of FIG. 1, the air pressure sensor 24 and the transmitter 26 are disposed on the left front wheel 14b. For example, the air pressure sensor 24 and the transmitter 26 may be integrated with a valve portion for taking air in and out of the tire inner space of the left front wheel 14b, or may be individually arranged at an arbitrary position of the left front wheel 14b. . The air pressure sensor 24 may always detect the air pressure in the tire or periodically. The transmitter 26 may transmit the pressure information every time pressure information is provided from the air pressure sensor 24, or may store a predetermined number of detection values (for example, 10 times) and collect the detected values at a predetermined timing. You may make it transmit toward. In addition to the pressure information, the transmitter 26 may transmit state information indicating the state of the tire such as tire temperature information and impact value information together with the pressure information as necessary. In addition, although the 315 MHz, 125 KHz, etc. which are used by the conventional TPMS can be used for the use frequency of the transmitter 26, another frequency can also be used suitably.

  A receiver 28 that receives a signal including pressure information transmitted from the transmitter 26 is disposed on the vehicle body 12. The receiver 28 is disposed at a position on the vehicle 10 such that the distances from the right front wheel 14a, the left front wheel 14b, the right rear wheel 14c, and the left rear wheel 14d mounted on the vehicle 10 are different. In the present embodiment, the position of the wheel 14 where the transmitter 26 is disposed is estimated based on the reception intensity of the signal received by the receiver 28. FIG. 2 shows the principle. For example, suppose that the transmitter 26 is arrange | positioned at each wheel 14a-14d, and is transmitting the signal with the same output. In this case, the reception intensity of the signal received by the receiver 28 varies depending on the position where the transmitter 26 is disposed. In the case of the example of FIG. 2, the receiver 28 is disposed in the vicinity of the left rear wheel 14d as in FIG. Therefore, the reception intensity of the signal received from the transmitter 26 arranged on the left rear wheel 14d is relatively strongest. Next, the signal having the relatively strong reception intensity is a signal from the transmitter 26 disposed on the right rear wheel 14c, and the next signal is a signal from the transmitter 26 disposed on the left front wheel 14b. The signal having the weakest reception intensity is a signal from the transmitter 26 disposed on the right front wheel 14a farthest from the receiver 28. Accordingly, by performing measurement in advance, it is possible to obtain an intensity range table of signal reception intensity for each of the wheels 14a to 14d as shown in FIG. In the case of FIG. 3, it is assumed that the reception intensity A <B <C <D. If the reception intensity actually received by the receiver 28 is x, if the reception intensity x of the signal received by the receiver 28 at a certain timing is included in the range of A ≦ x <B, the signal is placed on the right front wheel 14a. It can be determined that a signal has been received from the transmitter 26. Similarly, when the reception strength x of the received signal is included in the range of B ≦ x <C, it can be determined that the signal has been received from the transmitter 26 disposed on the left front wheel 14b, and the reception strength x of the received signal is When included in the range of C ≦ x <D, it can be determined that a signal has been received from the transmitter 26 disposed on the right rear wheel 14c. Further, when the received intensity x of the received signal is D ≦ x, it can be determined that the signal has been received from the transmitter 26 disposed on the left rear wheel 14d. That is, when the transmitter 26 is arranged on any one of the wheels 14a to 14d, the position of the wheel on which the transmitter 26 is arranged can be estimated by referring to the intensity range table of FIG. wear. Since this estimation can be performed every time a signal from the transmitter 26 is received, even if the wheel 14 is rotated and the position of the wheel 14 where the transmitter 26 is disposed changes, It can be estimated whether or not it is attached to the position. For example, when the reception intensity x of a signal received at a certain timing is included in the range of C ≦ x <D, it can be estimated that the wheel 14 is rotated and the reference wheel is changed to the right rear wheel 14c. This change information can also be used as tire or vehicle maintenance information.

  In addition, since various parts which comprise the vehicle body 12 exist between each wheel 14a-14d and the receiver 28, there is a high possibility that the signal received by the receiver 28 is affected by reflection. Similarly, there is a high possibility that the vehicle is affected by reflections from road structures such as road surfaces, parallel vehicles and guardrails. However, it can be considered that the influence of reflection by the components of the vehicle body 12 does not change. Further, with respect to reflection by the road surface, other vehicles, and road structures, reception by the receiver 28 is performed while the vehicle 10 is traveling, and the reflection state constantly changes. Therefore, using a vehicle having the same configuration as the vehicle 10 equipped with the tire pressure acquisition device, reception is performed a plurality of times while appropriately changing the road surface condition, the relationship with other vehicles, the relationship with the road structure, and the like. If a running test is performed and the average value is used, an intensity range table in consideration of the influence of reflection can be created. And even when the position of the transmitter 26 is actually estimated, the position estimation of the transmitter 26 in consideration of reflection is performed by comparing the average value of the received intensity of the signal acquired a plurality of times with the intensity range table of FIG. Can be implemented.

  Returning to FIG. 1, the receiver 28 provides the received pressure information of the air pressure sensor 24 to the TPMS-ECU 30. The TPMS-ECU 30 is also provided with dynamic state information based on the wheel speeds of the wheels 14a to 14d from the ABS-ECU 18. In the case of the present embodiment, the dynamic state information is information indicated by the wheels when the vehicle 10 is running, for example, a dynamic load radius that can be calculated based on the wheel speed (air pressure and load with the tire mounted on the vehicle). The distance from the wheel center to the ground contact surface when For example, if the air pressure value of the tire (wheel 14) decreases, the radius of the tire (wheel 14) also decreases according to the rate of decrease. Therefore, the dynamic load radius can be used as a value indicating the tire air pressure state. Further, if the vehicle 10 is traveling straight without acceleration / deceleration (no turning) and there is no slip in the tire, the amount of change in the dynamic load radius corresponds to the amount of change in the wheel speed. Therefore, the wheel speed of each wheel 14a-14d can be used as the movement state information of each wheel 14a-14d, and can be used as a value indicating the tire air pressure state.

  The TPMS-ECU 30 holds the intensity range table shown in FIG. 3 or information equivalent thereto, and based on the received intensity of the signal provided from the receiver 28, the wheel 14 on which the transmitter 26 and the air pressure sensor 24 are arranged. Is estimated. And this wheel 14 is recognized as a reference | standard wheel in the case of performing a tire air pressure acquisition process. Further, the TPMS-ECU 30 recognizes the position of the reference wheel and the pressure information (pneumatic pressure) of the reference wheel, the dynamic state information of the reference wheel at the estimated mounting position (for example, dynamic load radius), and the wheels 14 other than the reference wheel (estimated). Pressure information for each estimation target wheel is estimated based on dynamic state information (for example, dynamic load radius) of the target wheel. The TPMS-ECU 30 provides the estimated pressure information to the user (driver) via the display 32, a speaker (not shown), or the like by associating the estimated pressure information with each wheel 14 or converting it to a specific air pressure value. In the case of the configuration of FIG. 1, the TPMS-ECU 30 is a reference wheel position estimation unit that estimates the position of the reference wheel based on the received signal strength, and a pressure estimation that estimates pressure information of the estimation target wheel by comparison with the reference wheel. Means, it functions as an output means for determining the output form of the acquired or estimated value. Of course, the reference wheel position estimating means, the pressure estimating means, and the output means may each be constituted by separate processing units, or a processing unit combining arbitrary functions may be constituted.

  As described above, the radius of the tire changes according to the enclosed air pressure. And when the vehicle 10 equipped with wheels whose air pressure is reduced and the radius (dynamic load radius) is reduced travels straight without acceleration / deceleration, slip, etc., the tires whose air pressure has decreased do not have the air pressure decreased. It will rotate faster than the tire. In other words, when there is a wheel having a wheel speed larger than that of the other wheels when the vehicle 10 is traveling straight without slipping or the like, the radius of the wheel is smaller than the radius of the other wheel, that is, It can be determined that the air pressure is low. On the other hand, to change the tire dynamic load radius by 1 mm, it can be confirmed by experiment how much the air pressure in the tire should be changed. For example, in order to change the dynamic load radius of a 205 / 65R / 15 tire (standard diameter 647.5 mm) by 1 mm, it is possible to obtain a result that the air pressure needs to be reduced by 20 kPa.

  As described above, the reference wheel (the left front wheel 14b in the case of FIG. 1) has a known wheel mounting position by estimation based on the received intensity. Further, the actual air pressure value of the reference wheel (the left front wheel 14b) is known from the detection result (pressure information) of the air pressure sensor 24 transmitted by the transmitter 26. Further, the dynamic state information (dynamic load radius R0 or wheel speed V0) of the reference wheel at the estimated mounting position and the dynamic state information (dynamic load radius R or wheel speed V) of the estimation target wheel are obtained from the wheel speed sensors 16a to 16d. The measured value is known based on the detection result. Therefore, the pressure information of the estimation target wheel can be estimated by comparing the dynamic load radius R0 and pressure information of the reference wheel (the actual pressure value P0 actually measured by the air pressure sensor 24) with the dynamic state information of the estimation target wheel. it can. FIG. 4 is a diagram showing the relationship between the change amount of the dynamic load radius and the change amount of the air pressure value, and the horizontal axis indicates the difference (R0−R) between the dynamic load radius R0 of the reference wheel and the dynamic load radius R of the estimation target wheel. The vertical axis represents the difference (P0−P) between the air pressure value P0 of the reference wheel and the air pressure value P of the estimation target wheel. As described above, for example, when the value of R0-R is 1 mm, the value of P0-P can be derived as 20 kPa, for example. The relation information in FIG. 4 can be created by conducting an experiment in advance as described above.

  For example, the tire specifications of the reference wheel and the estimation target wheel are 205 / 65R / 15 tires (standard diameter 647.5 mm), and the dynamic load radius of the reference wheel (left front wheel 14b in FIG. 1) is 647.5 / 2. Assume that the tire pressure is 210 kPa. On the other hand, it is assumed that the dynamic load radius of the estimation target wheel (for example, the right front wheel 14a) is 645.5 / 2 (R0−R = 1 mm). In this case, referring to FIG. 4, the pressure is 20 kPa (= P0−P). That is, the air pressure of the estimation target wheel can be estimated to be 190 kPa (210-20).

  As described above, if the vehicle 10 travels straight (without turning) without acceleration / deceleration and there is no slip in the tire, the amount of change in the dynamic load radius and the amount of change in the wheel speed correspond. The vertical axis represents the difference between the air pressure value P0 of the reference wheel and the air pressure value P of the estimation target wheel (P0-P), and the horizontal axis represents the difference between the wheel speed V0 of the reference wheel and the wheel speed V of the estimation target wheel (V0-V). The relationship information may be used. However, when the air pressure value of the estimation target wheel is decreased with respect to the reference wheel, the estimation target wheel is larger in wheel speed than the reference wheel. Therefore, when the horizontal axis is the wheel speed difference, the graph is proportional to the lower right passing through the origin. In this case, even when no ABS is mounted, the pressure information of the estimation target wheel can be estimated directly from the pressure information of the reference wheel and the wheel speed of each wheel 14, and the same result as in the case of using the dynamic load radius is obtained. It is possible to simplify the system configuration.

  Thus, according to the tire pressure acquisition device of the present embodiment, the air pressure sensor 24 and the transmitter 26 arranged on any one wheel (reference wheel), and the vehicle 10 in which the distance from each wheel 14 is different. The position of the reference wheel can be estimated by the receiver 28 arranged at the upper position. Since this estimation is performed using the received intensity of the signal received by the receiver 28, it is possible even when the rotation of the wheel is performed, and the position of the reference wheel can always be accurately estimated. Further, the mounting positions of the wheels 14 other than the reference wheels can be determined on the basis of the air pressure value of the reference wheels whose mounting positions are estimated and the dynamic state information (dynamic load radius and wheel speed) of the wheels 14 including the reference wheels. 14 pressure information can be estimated. The pressure information estimated at each wheel 14 can be converted into a specific air pressure value based on the air pressure value of the reference wheel.

  FIG. 5 is a flowchart for explaining the processing procedure of the tire pressure acquisition device described above. The processing flow of the tire pressure acquisition device may be automatically executed at an arbitrary timing when the vehicle 10 is in a traveling state, for example. Alternatively, it may be executed at a timing desired by the driver by pressing the air pressure check switch.

  When the processing flow is executed, the ABS-ECU 18 acquires the wheel speed of each wheel 14 via the right front wheel speed sensor 16a, the left front wheel speed sensor 16b, the right rear wheel speed sensor 16c, and the left rear wheel speed sensor 16d. (S100). Further, the ABS-ECU 18 determines whether or not the vehicle 10 is traveling straight ahead based on information from the steering sensor 22, for example (Y or N in S102), and provides the determination result to the TPMS-ECU 30. . Whether or not the vehicle is traveling straight ahead can be determined based on the detected value when a lateral G sensor or a yaw rate sensor is mounted in addition to the information from the steering sensor 22, for example. Further, when the wheel speed difference between the right front wheel speed sensor 16a and the left front wheel speed sensor 16b is greater than or equal to a predetermined value (a difference that is much larger than the wheel speed difference due to the difference in tire air pressure), it is determined that the vehicle 10 is turning. it can. Therefore, it may be determined that the vehicle is turning based on the values of the right front wheel speed sensor 16a and the left front wheel speed sensor 16b.

  When the TPMS-ECU 30 determines from the information from the ABS-ECU 18 that the vehicle 10 is not traveling straight, that is, is turning (N in S102), the wheel speed changes, so the wheel movement state information becomes unstable. Therefore, since the estimation accuracy decreases, the processing flow of the tire air pressure acquisition device is terminated. And it waits until the next tire air pressure acquisition timing. Further, when the TPMS-ECU 30 determines that the vehicle 10 is currently traveling straight (Y in S102), the TPMS-ECU 30 determines whether or not each wheel 14 is slipped from information on each wheel speed obtained from the ABS-ECU 18. (Y or N in S104). For example, when a certain wheel is slipping, only a slipping wheel can obtain a significantly higher wheel speed than the other wheels. When it can be determined that the wheel is slipping (Y in S104), since the wheel speed changes, the wheel movement state information becomes unstable and the estimation accuracy decreases. The processing flow of is terminated. And it waits until the next tire air pressure acquisition timing. Since the engine torque decreases when the wheel 14 is slipping, the presence or absence of slip may be determined based on the engine torque value provided from the engine ECU or the like.

  When it is determined that all wheels are not slipping (N in S104), the TPMS-ECU 30 determines whether the vehicle 10 is currently accelerating or decelerating (Y or N in S106). Whether or not acceleration / deceleration is being performed can be determined based on a change in engine torque, a change in vehicle speed sensor, or the like. When the TPMS-ECU 30 determines that the vehicle 10 is accelerating or decelerating (Y in S106), the wheel speed changes, so the wheel movement state information becomes unstable and the estimation accuracy decreases. This processing flow is terminated, and the system waits for the next tire pressure acquisition timing.

  If the TPMS-ECU 30 determines that the vehicle 10 is not accelerating or decelerating, that is, is traveling at a constant speed (N in S106), has it received a signal from the transmitter 26 within a predetermined time via the receiver 28? It is determined whether or not (Y or N in S108). For example, if the receiver 28 cannot receive a signal from the transmitter 26 within 10 seconds after the conditions of S100 to S106 are met (N in S108), the TPMS-ECU 30 determines that a system abnormality has occurred in the tire pressure acquisition device. Then, the system abnormality signal is provided to the display 32 (S110). In response to the system abnormality signal, the display 32 turns on an LED indicating an error of the tire pressure acquisition device or displays an error message, for example. Thereafter, the TPMS-ECU 30 ends the processing flow of the tire pressure acquisition device. The system abnormality signal may be a signal indicating abnormality of the entire tire pressure acquisition device, or may be a signal indicating individual abnormality such as the air pressure sensor 24, the transmitter 26, and the receiver 28.

  When it is determined that the receiver 28 has normally received the signal from the transmitter 26 (Y in S108), the TPMS-ECU 30 stores the information in the memory (S110). The TPMS-ECU 30 determines whether or not the receiver 28 has normally received a signal from the transmitter 26 a predetermined number of times after the conditions of S100 to S106 have been met (Y or N in S112). For example, the transmitter 26 can transmit information detected by the air pressure sensor 24 to the transmitter 26 at intervals of one second. The TPMS-ECU 30 repeats the reception and storage operation until the information related to the tire pressure is acquired a predetermined number of times, for example, 20 times continuously and stored in the memory in S112 (N in S112).

  For example, when the information about the tire pressure is continuously acquired 20 times (Y in S112), the TPMS-ECU 30 estimates the position of the wheel 14 (reference wheel) on which the air pressure sensor 24 and the transmitter 26 are arranged (S114). As described with reference to FIGS. 2 and 3, the reference wheel mounting position is estimated based on the reception intensity of the signal acquired by the receiver 28. As described above, the receiver 28 is arranged at different distances from the wheels 14 mounted on the vehicle 10, so that the air pressure sensor 24 and the transmitter 26 are actually attached to any one wheel 14. When arranged, the received signal strength is included in any of the strength ranges shown in FIG. In the case of the present embodiment, for example, when the signal intensity x received by the receiver 28 is included in the intensity range B ≦ x <C, it is estimated that the transmitter 26 is disposed on the left front wheel 14b. As described above, the radio wave transmitted from the wheel 14 of the traveling vehicle 10 may be reflected on the components of the vehicle body 12, the road surface, the parallel running vehicle, the roadside structure, and the like. For this reason, in the present embodiment, the reception intensity of signals received a predetermined number of times (for example, 20 times) is averaged, and the average value is used as the reception intensity when the position is estimated. An intensity range table (data) prepared in advance is also formed in consideration of various reflection effects. As described above, it is possible to perform transmitter position estimation in which the influence of reflection and the like is reduced by using the average value of the reception intensity.

  When the position estimation of the reference wheel (in the present embodiment, the left front wheel 14b) is completed, the TPMS-ECU 30 acquires the air pressure value actually acquired from the reference wheel (S116). When the TPMS-ECU 30 obtains the air pressure value of the reference wheel, the ABS-ECU 18 obtains the dynamic load radius of each wheel 14 calculated based on the wheel speed obtained in S100, and uses the relationship information shown in FIG. Based on the dynamic load radius and air pressure value of the wheel and the dynamic load radius of the estimation target wheel, the air pressure value of the estimation target wheel is estimated (S118). In the present embodiment, the left front wheel 14b is a reference wheel, and the other wheels, the right front wheel 14a, the right rear wheel 14c, and the left rear wheel 14d are estimation target wheels.

  After acquiring the actually measured air pressure value of the reference wheel and the estimated air pressure value of each estimation target wheel, the TPMS-ECU 30 determines whether the air pressure value of each wheel 14 is within a preset tire air pressure setting range (S120). . The setting range of the tire air pressure can be set in advance, for example, 210 ± 10 kPa in consideration of the performance of the vehicle and the tire. If there is a wheel 14 showing an air pressure value that is out of this range, it is determined that the tire air pressure is abnormal (Y in S122). Then, the TPMS-ECU 30 performs an abnormality display output using the display 32 (S124). Abnormality indication can be “There are tires with low air pressure. Please check and maintain as soon as possible.” Further, as described above, since the position of the reference wheel and the position of the estimation target wheel are also known, it is possible to output a message specifying the wheel whose air pressure value has decreased. For example, “The air pressure value of the right front wheel has dropped. Please check and perform maintenance immediately”. Further, the air pressure value may be specifically added to the message. Such a message may be output only visually, such as displaying a text message or lighting a warning lamp, or may be output as an audio message such as a voice message or warning sound via a speaker. In the case of an abnormal display, it is desirable to strongly alert the driver by outputting a visual message and an audio message together.

  When the abnormality display output is executed, the TPMS-ECU 30 stores the abnormality history in the memory, holds the abnormal state after the ignition key of the vehicle 10 is removed, and operates the ignition key again. It is desirable to perform an abnormal output before the vehicle 10 travels. Further, when displaying the tire pressure value of the tire whose air pressure value has decreased, the TPMS-ECU 30 continuously monitors the tire air pressure value after the abnormality display output in S124, and provides the driver with the change of the air pressure value. It may be.

  On the other hand, when it is determined in S122 that there is no abnormality in the air pressure value of each wheel 14 (N in S122), the TPMS-ECU 30 performs a normal display output indicating that the tire air pressure value is normal via the display 32 or the like (S126). ). In the case of normal display output, for example, it is desirable to use a display form that does not interfere with the driving of the driver only by turning on an LED indicating normal air pressure. Note that the TPMS-ECU 30 may store history data when the air pressure value is normal and use the history data as vehicle or tire maintenance data.

  As described above, according to the present embodiment, it is possible to obtain the air pressure values of all the wheels and perform the tire air pressure drop alarm processing for each wheel only by providing the air pressure sensor 24 and the transmitter 26 on one wheel. Further, as described above, since the estimation of the reference wheel can be performed by receiving the signal transmitted from the transmitter 26 by the receiver 28, for example, even when the wheel 14 is rotated, the reference wheel is estimated. Can be estimated. Further, if at least one wheel including the air pressure sensor 24 and the transmitter 26 is included, even if a new wheel 14 is mounted, the tire pressure value can be estimated in the same manner as in the present embodiment, and the same effect can be obtained. Can be obtained.

  In the present embodiment, as an example of the tire pressure acquisition device having the simplest configuration and the greatest economic effect, the case where the wheel on which the air pressure sensor 24 and the transmitter 26 are arranged is a single wheel has been described, but the air pressure sensor 24 and the transmitter There may be a plurality of reference wheels on which 26 is arranged. In this case, when estimating the pressure information of the estimation target wheel, the air pressure value of the estimation target wheel can be estimated using any one reference wheel as a comparison target.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each figure is for explaining an example, and any configuration that can achieve the same function can be changed as appropriate, and the same effect can be obtained. It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, etc. are also effective as an aspect of the present invention.

1 is a conceptual explanatory diagram of a vehicle including a tire air pressure acquisition device according to an embodiment of the present invention. It is explanatory drawing explaining the difference of the receiving intensity | strength of the signal which a receiver receives at that time, and the arrangement | positioning relationship between a transmitter and a receiver in the tire pressure acquisition apparatus which concerns on this embodiment of this invention. It is explanatory drawing explaining the relationship between the intensity | strength range of the signal which the receiver of the tire pressure acquisition apparatus which concerns on this embodiment of this invention receives, and the position of a wheel. It is explanatory drawing explaining the relationship between the difference of the dynamic load radius of the reference | standard wheel and the estimation object wheel, and the difference of a tire air pressure value in the tire air pressure acquisition apparatus which concerns on this embodiment of this invention. It is a flowchart explaining the process sequence of the tire pressure acquisition apparatus which concerns on this embodiment of this invention.

Explanation of symbols

  10 vehicle, 12 vehicle body, 14 wheels, 14a right front wheel, 14b left front wheel, 14c right rear wheel, 14d left rear wheel, 16 wheel speed sensor, 16a right front wheel speed sensor, 16b left front wheel speed sensor, 16c right rear wheel speed sensor 16d Left rear wheel speed sensor, 18 ABS-ECU, 20 Steering, 22 Steering sensor, 24 Air pressure sensor, 26 Transmitter, 28 Receiver, 30 TPMS-ECU, 32 Display.

Claims (5)

An air pressure sensor that acquires pressure information inside the tire using at least one of a plurality of wheels mounted on the vehicle as a reference wheel; and
A transmitter that is disposed on the reference wheel and transmits a signal including pressure information acquired by the air pressure sensor to the vehicle;
A receiver for receiving a signal from the transmitter, the receiver being disposed at a position on the vehicle such that the distance from each wheel mounted on the vehicle is different;
Reference wheel position estimating means for estimating the mounting position of the reference wheel based on the received intensity of the signal received by the receiver;
Wheel state information acquisition means for acquiring dynamic state information based on wheel speed for each of the plurality of wheels;
Based on the pressure information of the reference wheel and the dynamic state information acquired for the wheel at the estimated mounting position, and the dynamic state information acquired by the estimation target wheel other than the reference wheel, the pressure information of the estimation target wheel is obtained. Pressure estimating means for estimating;
Output means for outputting a result including the pressure information;
A tire pressure acquisition device comprising:   The tire pressure acquisition device according to claim 1, wherein the output means outputs the position information of the wheel mounted in the vehicle and the pressure information in association with each other.   The tire pressure acquisition device according to claim 1 or 2, wherein the output means outputs a tire air pressure value of a wheel estimated from the pressure information.   4. The tire pressure acquisition device according to claim 1, wherein the output unit outputs a warning when a tire pressure value based on the pressure information is equal to or less than a predetermined value. 5. . A signal including tire pressure information is transmitted to a receiver arranged at a position on the vehicle such that the distance from each wheel is different using any at least one of a plurality of wheels mounted on the vehicle as a reference wheel. And steps to
Estimating the mounting position of the reference wheel on the vehicle based on the received intensity of the signal received by the receiver;
Obtaining dynamic state information based on wheel speed for each of the plurality of wheels;
Based on the pressure information of the reference wheel and the dynamic state information acquired for the wheel at the estimated mounting position, and the dynamic state information acquired by the estimation target wheel other than the reference wheel, the pressure information of the estimation target wheel is obtained. Estimating, and
Outputting a result including the pressure information;
A method for obtaining tire air pressure, comprising:

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