JP2008087574A - Wheel state detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detect wheel states by employing a constitution of a wheel state detecting unit mounted in a wheel. <P>SOLUTION: In a tire pneumatic pressure monitoring system, a TPMS valve unit 16 includes a first strain sensor 56 and second strain sensor 58 for detecting the extension/contraction amount in the axial direction of a tire valve 30. An air leakage determination part determines whether or not air leakage occurs in a tire by determining whether or not the detected extension amount of the tire valve 30 is a prescribed value or lower. A display control part displays the occurrence of the air leakage on the display when the air leakage is determined to occur in a tire. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel state detection device, and more particularly to a wheel state detection device including a wheel state detection unit that detects a wheel state.

  In recent years, in order to realize safer vehicle driving, tire pressure monitoring system (TPMS: Tire Pressure Monitoring System) has been developed to transmit information such as tire pressure and temperature wirelessly to the vehicle body to inform the driver. It has been. However, there are various other parameters that represent the state of the wheel. By detecting more types of wheel states, it is possible to notify a vehicle occupant of a warning or to control the vehicle using the detected wheel states.

  For this reason, for example, Patent Document 1 proposes an air pressure monitor unit having a centrifugal force sensor unit that includes a sensor sensing unit and a strain gauge that connects the sensor sensing unit to the unit body. Further, for example, Patent Document 2 proposes an axle force detection device in which a strain sensor is provided in a disc portion and a force acting on the axle is calculated based on the strain of the disc portion and the rotational speed of the axle.

For example, Patent Document 3 proposes a tire pressure detection device that detects the tire air pressure using a giant magnetostrictive material, and Patent Document 4, for example, uses a sensor that detects strain for bolt tightening. Sensor bolts that detect the occurrence of loosening have been proposed.
JP 2003-226121 A JP-A-9-292294 JP-A-11-287725 Japanese Patent Application Laid-Open No. 11-118637

  In order to make it possible to detect more wheel states, for example, if many configurations are added as described in Patent Document 1 described above, the number of parts increases accordingly, which causes an increase in cost.

  This invention is made | formed in view of such a subject, The objective is to detect more wheel states easily by utilizing the structure of the wheel state detection unit attached to a wheel.

  In order to solve the above-described problems, a wheel state detection device according to an aspect of the present invention includes a tire valve and a unit main body fixed to one end of the tire valve, and the tire valve is fixed to a wheel rim. In a wheel state detection device including a wheel state detection unit attached to a wheel, the wheel state detection unit includes a valve deformation sensor that detects an amount of expansion and contraction in the axial direction of the tire valve.

  According to this aspect, by using the axial expansion / contraction amount of the tire valve included in the wheel state detection unit, for example, the looseness of the nut fastened to the tire valve or the force in the tire valve axial direction acting on the wheel state detection unit The wheel state such as can be detected. For this reason, it can suppress adding a new structure in order to detect many wheel states.

  The wheel state detection unit is attached to a wheel by inserting a tire valve into a valve insertion hole connecting the tire chamber and an outside provided in the wheel rim and fastening the wheel valve so that the valve insertion hole is shielded. An air leakage determination means for determining whether or not an air leakage has occurred in the tire by determining whether or not the detected axial extension amount of the tire valve is equal to or less than a predetermined threshold value. When it is determined that an air leak has occurred, an air leak notification means for notifying the passenger of the vehicle to that effect may be further provided.

  According to this aspect, it is possible to detect tire air leakage using the axial expansion and contraction amount of the tire valve included in the wheel state detection unit. For this reason, it becomes possible to alert | report the air leak of a tire to the passenger | crew of a vehicle by simple structure.

  The wheel state detection device according to the present aspect includes an air pressure sensor that detects tire air pressure, tire air pressure determination means that determines whether or not the detected tire air pressure has decreased to a predetermined value or less, and the detected tire air pressure is When it is determined that the air pressure has decreased to a predetermined value or less, it may further include an air pressure decrease informing means for informing the vehicle occupant to that effect. The air pressure decrease notifying means determines that the tire air pressure has decreased due to tire air leakage when it is determined that the tire air pressure has decreased below a predetermined value and it is determined that air leakage has occurred in the tire. May be notified.

  For example, if the tire pressure drops due to the tire itself being damaged, the tire is likely to have to be replaced afterwards. On the other hand, for example, if the tire air pressure drops due to air leaks due to loose tightening of the tire valve, etc., it is not necessary to replace the tire if air is supplied to the tire without forcibly driving the vehicle. is there. According to this aspect, when the tire air pressure decreases, it is possible to notify the vehicle occupant of whether the tire air pressure is due to air leakage or other factors. Appropriate measures can be taken accordingly.

  The valve deformation sensor may also detect a radial bending amount that is a bending amount of the tire valve when the unit main body portion is displaced in the wheel radial direction. In a wheel state detection unit of a type in which a unit main body is fixed to one end of a tire valve, a bending force is applied to the tire valve by the mass of the unit main body when the wheel rotates or an external force is applied to the wheel. According to this aspect, such a wheel state can be detected with a simple configuration by detecting the radial bending amount of the tire valve using the configuration of the wheel state detection unit.

  The valve deformation sensor detects the axial distortion of the outer part of the wheel diameter and the axial distortion of the inner part of the wheel diameter on the inner peripheral surface of the air supply hole of the tire valve, thereby expanding and contracting the tire valve in the axial direction. The radial bending amount, which is the bending amount of the tire valve when the unit main body portion is displaced in the wheel radial direction, may be detected. According to this aspect, it is possible to detect both the amount of expansion and contraction in the axial direction of the tire valve and the amount of bending in the radial direction of the tire valve with a simple configuration of detecting strain at two locations.

  The wheel state detection unit is attached to a wheel by inserting a tire valve into a valve insertion hole connecting the tire chamber and an outside provided in the wheel rim and fastening the wheel valve so that the valve insertion hole is shielded. It may be attached. The wheel state detection device according to this aspect determines whether or not an air leak has occurred in the tire by determining whether or not the detected axial extension of the tire valve is equal to or less than a predetermined threshold. If it is determined that air leakage has occurred, the determination means may further include air leakage notification means for notifying the passenger of the vehicle to that effect. The air leakage determination means changes the threshold value of the amount of expansion and contraction in the axial direction of the tire valve when determining whether or not air leakage has occurred in the tire according to the detected radial bending amount of the tire valve. Also good.

  When a bending force is applied to the tire valve, tire air leakage is more likely to occur due to weak fastening of the tire valve to the wheel rim. According to this aspect, it is possible to increase the determination accuracy of the occurrence of tire air leakage with a simple configuration.

  The wheel state detection apparatus according to this aspect may further include a wheel speed estimation unit that estimates the rotation speed of the wheel using the detected radial bending amount of the tire valve. The tire valve is given a bending force outwardly of the wheel diameter according to the rotational speed of the wheel due to the mass of the unit main body. According to this aspect, the wheel speed can be easily estimated using the configuration of the wheel state detection unit.

  The wheel state detection unit may further include a tire pressure sensor that detects tire pressure. Tire durability that determines whether the tire pressure detected from the past to the present and the wheel rotational speed estimated from the past to the present satisfy a predetermined condition related to the durability of the tire The tire endurance when it is determined that the tire determination means, the tire air pressure detected from the past to the present, and the wheel rotational speed estimated from the past to the present satisfy the predetermined condition. Tire durability notifying means for notifying the vehicle occupant that the performance has decreased.

  The durability of the tire can be accurately estimated by clarifying the tire air pressure and the travel distance of the vehicle. According to this aspect, the travel distance of the vehicle can be easily calculated using the detected wheel speed. For this reason, it becomes possible to easily determine the durability of the tire by using the detected tire pressure and the calculated wheel speed.

  The wheel state detection device according to the present aspect estimates the external force applied to the wheel using the detected radial bending amount of the tire valve, and the estimated external force satisfies a predetermined condition related to tire damage. Tire damage determination means for determining whether or not, and external force notification means for notifying a vehicle occupant that the tire has been damaged when it is determined that the estimated external force satisfies the predetermined condition; May be further provided.

  If a large external force is applied to the wheel, the wheel may be damaged. In addition, when a wheel is damaged due to some cause, a specific vibration may occur in the wheel due to the rotation of the wheel. According to this aspect, it is possible to easily estimate the external force applied to the wheel by using the detected radial bending amount of the tire valve. For example, when a large damage is applied to the tire, the vehicle occupant This can be quickly notified.

  Another embodiment of the present invention is also a wheel state detection device. This device includes a tire valve and a unit body portion fixed to one end of the tire valve, and a wheel state detection device including a wheel state detection unit attached to a wheel by fixing the tire valve to a wheel rim. The wheel state detection unit includes a valve deformation sensor that detects a radial bending amount that is a bending amount of the tire valve when the unit main body portion is displaced in the wheel radial direction.

  According to this aspect, it is possible to easily detect the radial bending amount of the tire valve using the configuration of the type wheel state detection unit in which the unit main body is fixed to one end of the tire valve. The amount of radial bending of the tire valve is detected by the valve deformation sensor detecting the axial distortion of the outer part of the wheel diameter and the axial distortion of the inner part of the wheel diameter of the inner peripheral surface of the air supply hole of the tire valve. It may be done by doing.

  Yet another embodiment of the present invention is also a wheel state detection device. This device has a tire valve and a unit main body fixed to one end of the tire valve, and is a wheel state detection unit that is attached to a wheel by fixing the tire valve to a wheel rim, and detects tire air pressure. Air pressure sensor, a valve deformation sensor for detecting the amount of expansion and contraction of the tire valve in the axial direction, data indicating the detected tire air pressure, and data indicating the amount of expansion and contraction in the axial direction of the tire valve are wirelessly transmitted to the outside. The tire pressure is reduced to a predetermined value or less by using the wheel state detection unit having the transmission means, the reception means for receiving the data transmitted by the transmission means, and the data indicating the received tire pressure. Tire pressure determination means for determining whether or not, and the received data indicating the amount of expansion and contraction of the tire valve in the axial direction An air leak determining means for determining whether or not an air leak has occurred in the tire by determining whether or not the detected axial expansion amount of the tire valve is equal to or less than a predetermined threshold, and tire pressure When it is determined that the air pressure has decreased to a predetermined value or less, the air pressure decrease notification means for informing the vehicle occupant to that effect, and when it is determined that air leakage has occurred in the tire, the vehicle Air leak notification means for notifying the passenger.

  Since the wheel rotates at a high speed, the wheel state detection unit attached to the wheel is generally provided with a transmitting means for transmitting information to the outside by radio, and a receiving means for receiving the information is provided on the vehicle body side. According to this aspect, it is possible to transmit the data indicating the amount of expansion and contraction in the axial direction of the tire valve to the vehicle body side using the transmission means for transmitting data indicating the tire air pressure, and by expanding the types of wheel states to be detected An increase in cost can be suppressed.

  According to the wheel state detection device of the present invention, more wheel states can be easily detected by using the configuration of the wheel state detection unit attached to the wheel.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a vehicle 10 equipped with a tire pressure monitoring system 200 according to the present embodiment. The vehicle 10 is configured with wheels 14 assembled to a vehicle body 12. Each wheel 14 has a tire and a wheel. In the vehicle 10 according to the first embodiment, so-called run-flat tires are employed as the tires provided on the wheels 14, and specifically, side-reinforced run-flats that enable run-flat travel when air pressure decreases. Tires are used. However, general tires other than run-flat tires may be employed.

  The tire pressure monitoring system 200 functions as a wheel state detection device that detects a wheel state, and includes a TPMS valve unit 16, a receiver 18, a display 20, and an electronic control unit (hereinafter referred to as “ECU”) 100. . A TPMS valve unit 16 is attached to each of the wheels 14. Each TPMS valve unit can be identified by an ID as will be described later. Each of the TPMS valve units 16 wirelessly transmits wheel state information regarding the detected wheel state toward the vehicle body 12 as described later.

  The receiver 18 receives unit data including wheel state information transmitted from the TPMS valve unit 16 by radio. The receiver 18 is connected to the ECU 100, and the wheel state information received by the receiver 18 is output to the ECU 100.

  The display 20 is disposed at a location that can be visually recognized by the driver, such as an instrument panel in the vehicle compartment. The display 20 is connected to the ECU 100 and displays information on the screen according to display data output from the ECU 100.

  2 is a cross-sectional view of the wheel 14 including the TPMS valve unit 16 according to the present embodiment, and FIG. 3 is a view of the TPMS valve unit 16 viewed from the viewpoint P in FIG. For easy understanding, FIG. 2 shows a part of the TPMS valve unit 16 and the wheel 22 in a cross section.

  The wheel 14 has a wheel 22 and a tire 24. A wheel rim 22 a formed in a cylindrical shape is provided on the outer peripheral portion of the wheel 22. A tire 24 is assembled on the outer periphery of the wheel rim 22a. A tire air chamber 26 is formed in a region surrounded by the inside of the tire 24 and the outer periphery of the wheel rim 22a.

  The TPMS valve unit 16 includes a tire valve 30, a unit main body 28, and a grommet 32. The tire valve 30 is formed in a cylindrical shape provided with an air supply hole 30a penetrating in the axial direction, and has a male screw portion on the outside. The unit main body 28 is fixed to one end of the tire valve 30.

  The unit main body 28 includes a battery 40 and a base 38. The base 38 is provided with a processing device to be described later. In addition to this, the unit main body 28 includes an air pressure sensor (not shown), a temperature sensor (not shown), and a transmitter (not shown). The grommet 32 is formed of an elastic material such as rubber and is provided so as to cover the outer periphery of the tire valve 30 on the side to which the unit main body 28 is fixed. The battery 40 supplies power to the processing device of the base 38 and the like. For this reason, the TPMS valve unit 16 can detect the tire air pressure and the tire chamber temperature and transmit the wheel state information without receiving power from the vehicle body 12.

  The wheel rim 22a is provided with a valve insertion hole 22b through which the tire valve 30 is inserted so as to connect the tire air chamber 26 and the outside. The tire valve 30 is inserted into the valve insertion hole 22b from the outer peripheral side of the wheel rim 22a, and the nut 34 is screwed into the male screw portion on the outer periphery of the tire valve 30 through the washer 36 from the inner peripheral side of the wheel rim 22a. Thus, the TPMS valve unit 16 is attached to the wheel rim 22a.

  By attaching the TPMS valve unit 16 to the wheel rim 22a in this manner, the valve insertion hole 22b is shielded by the grommet 32, and air leakage from the tire air chamber 26 to the outside is suppressed. At this time, the tire valve 30 is in a state in which a tensile force is applied by fastening the nut 34.

  If the nut 34 is loosened, the force for shielding the valve insertion hole 22b by the grommet 32 is weakened, and the possibility of air leakage from the valve insertion hole 22b increases. For this reason, the TPMS valve unit 16 according to the present embodiment includes a first strain sensor 56 and a second strain sensor 58 that detect the amount of expansion and contraction of the tire valve 30 in the axial direction.

  The first strain sensor 56 is attached to the outer side of the wheel diameter of the air supply hole 30 a of the tire valve 30, and the second strain sensor 58 is attached to the inner side of the wheel diameter of the air supply hole 30 a of the tire valve 30. By providing the strain sensors in two places as described above, the amount of expansion and contraction in the axial direction of the tire valve 30 can be detected with high accuracy.

  The first strain sensor 56 and the second strain sensor 58 employ a cross gauge that detects strain in two orthogonal directions. In the present embodiment, the first strain sensor 56 and the second strain sensor 58 are attached to the inner wall of the air supply hole 30a so that the axial direction of the tire valve 30 and the two detection directions of the cross gauge form 45 °. . By using the cross gauge in this manner, it is possible to remove distortions other than the axial direction of the tire valve 30 by a later calculation, so that the axial distortion of the tire valve 30 can be accurately detected. It becomes.

  In the TPMS valve unit 16 of the type in which the unit main body 28 is fixed to one end of the tire valve 30 like the TPMS valve unit 16 according to this embodiment, the unit main body 28 is cantilevered by the tire valve 30. Will be supported. For this reason, when the wheel rotates or an external force is applied to the wheel, the unit main body 28 is displaced in the wheel radial direction. At this time, a bending force is applied to the tire valve 30. In this way, by attaching the first strain sensor 56 and the second strain sensor 58 so as to face the wheel diameter outer portion and the wheel diameter inner portion, respectively, not only the amount of expansion and contraction of the tire valve 30 in the axial direction is achieved. The radial bending amount, which is the bending amount of the tire valve 30 when the unit main body 28 is displaced in the wheel radial direction, can be detected. Therefore, it is possible to detect the wheel speed and the external force applied to the wheel by using the detected radial bending amount.

  In order to accurately detect the amount of bending in the radial direction of the tire valve 30, the first strain sensor 56 and the second strain sensor 58 are tires having the highest strain detection sensitivity when the unit main body 28 is displaced in the wheel radial direction. It is attached to the axial position of the valve 30. In this embodiment, as such a position, the first strain sensor 56 and the second strain sensor 58 are arranged at a position that overlaps with the space inside the valve insertion hole 22b and slightly close to the washer 36 side.

  Thus, the first strain sensor 56 and the second strain sensor 58 are the radial direction that is the amount of expansion and contraction in the axial direction of the tire valve 30 and the amount of bending of the tire valve 30 when the unit main body 28 is displaced in the wheel radial direction. It functions as a valve deformation sensor that detects the amount of bending. By attaching the first strain sensor 56 and the second strain sensor 58 to the inner wall of the air supply hole 30a of the tire valve 30 to the outer portion of the wheel diameter and the inner portion of the wheel diameter, a number of wheels can be utilized using the configuration of the TPMS valve unit 16. The state can be detected.

  FIG. 4 is a functional block diagram of the TPMS valve unit 16. The TPMS valve unit 16 includes a transmitter 50, an air pressure sensor 52, a temperature sensor 54, a first strain sensor 56, a second strain sensor 58, and a processing device 60.

  The air pressure sensor 52 detects the air pressure of the tire chamber 26 as a wheel state (hereinafter referred to as “tire air pressure”). The temperature sensor 54 detects the temperature of the tire chamber 26 as a wheel state. Therefore, the TPMS valve unit 16 functions as a wheel state detection unit that detects a wheel state. The air pressure sensor 52 and the temperature sensor 54 are connected to the processing device 60, and detection results from the air pressure sensor 52 and the temperature sensor 54 are output to the processing device 60.

  As described above, the first strain sensor 56 detects the strain in the axial direction of the tire valve 30 at the outer side of the tire diameter of the tire valve 30, and the second strain sensor 58 is the axis of the tire valve 30 at the inner side of the tire diameter of the tire valve 30. Detect direction distortion. The first strain sensor 56 and the second strain sensor 58 are connected to the processing device 60, and detection results by the first strain sensor 56 and the second strain sensor 58 are output to the processing device 60.

  The processing device 60 is configured by a microprocessor and includes an information processing unit 62, a timer 64, and a storage unit 66. The timer 64 measures time. The storage unit 66 stores a unit ID used as identification information for identifying the TPMS valve unit 16.

  The information processing unit 62 refers to the time measured by the timer 64 and uses the detection results of the air pressure sensor 52 and the temperature sensor 54 at predetermined time intervals such as every 10 seconds, for example, tire air pressure information and tire air chamber temperature information. To get. The information processing unit 62 generates unit data including the acquired tire pressure information and tire chamber temperature information.

  The structure of the unit data 70 is shown in FIG. The information processing unit 62 generates detection timing information 84 using the detection time measured by the timer 64. The information processing unit 62 uses the tire pressure information 76 acquired from the air pressure sensor 52, the tire chamber temperature information 78 acquired from the temperature sensor 54, the first strain information 80 acquired from the first strain sensor 56, and the second strain sensor 58. In addition to the acquired second distortion information 82, the generated detection timing information 84 is combined to generate wheel state information 74. The information processing unit 62 acquires the unit ID 72 from the storage unit 66. The information processing unit 62 generates a series of unit data 70 by combining the unit ID 72 and the wheel state information 74. Accordingly, the unit data 70 is composed of a unit ID 72 and wheel state information 74. The wheel state information 74 includes tire air pressure information 76, tire air chamber temperature information 78, first strain information 80, second strain information 82, and detection timing information 84. Consists of.

  Returning to FIG. 4, the transmitter 50 transmits the unit data 70 generated by the information processing unit 62 of the processing device 60 to the vehicle body 12 at predetermined time intervals. However, in consideration of battery power saving, the transmission time interval of the unit data 70 by the transmitter 50 is set longer than the detection time interval by the air pressure sensor 52 and the temperature sensor 54. The unit data 70 is transmitted to the vehicle body 12 every time. For this reason, until transmission by the transmitter 50 is performed, the storage unit 66 of the processing device 60 stores tire pressure information 76, tire chamber temperature information 78, and detection timing information 84 for several detections. These are included in the wheel state information 74.

  FIG. 6 is a functional block diagram of components mounted on the vehicle body 12 among the components of the tire pressure monitoring system 200. In FIG. 6, the ECU 100 is realized by cooperation of hardware such as a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, and software. The function block to be performed is drawn. Therefore, these functional blocks can be realized in various forms by a combination of hardware and software.

  The ECU 100 includes a tire air pressure determination unit 102, an air leak determination unit 104, a wheel speed estimation unit 106, a tire durability determination unit 108, a tire damage determination unit 110, a display control unit 112, and a storage unit 114.

  The display control unit 112 uses the tire air pressure information 76 and the tire air chamber temperature information 78 to generate display data for displaying the tire air pressure and the tire air chamber temperature on the display 20. Further, when it is determined that the tire air pressure is higher than the predetermined threshold pressure, or when it is determined that the tire chamber temperature is higher than the predetermined threshold temperature, the display control unit 112 displays a warning on the display 20. Generate display data. The display 20 displays information such as a warning message using the display data generated by the display control unit 112.

  The storage unit 114 is configured by nonvolatile storage means such as a ROM. The storage unit 114 stores in advance threshold values and the like used when performing determinations and estimations performed in the ECU 100. The storage unit 114 stores the unit ID 72 of each TPMS valve unit 16 and the mounting position of the TPMS valve unit 16 in association with each other.

  The tire pressure determination unit 102 determines whether the tire pressure of each vehicle body 12 has decreased to a predetermined value or less using the tire pressure information 76 included in the wheel state information 74 of the received unit data 70. . When it is determined that the tire air pressure of any vehicle body 12 has decreased to a predetermined value or less, the display control unit 112 displays that fact on the display 20. Therefore, the display control unit 112 and the display 20 function as an air pressure decrease notification unit that notifies the vehicle occupant that the tire air pressure is decreasing.

  At this time, the tire air pressure determination unit 102 specifies the unit ID 72 included in the unit data 70 including the first strain information 80 and the second strain information 82 that is the basis for determining that the tire air pressure is decreasing. Next, the tire air pressure determination unit 102 refers to the correspondence relationship between the unit ID 72 stored in the storage unit 114 and the mounting wheels of the TPMS valve unit 16, and identifies the mounting position of the TPMS valve unit 16 that has transmitted the unit data 70. Thus, the wheel 14 determined that the tire air pressure has decreased is specified. The display control unit 112 causes the display 20 to display the wheel 14 that has been determined that the tire air pressure has decreased, together with the fact that air leakage has occurred. As a result, the vehicle occupant can easily know which wheel 14 the tire air pressure is decreasing.

  The air leak determination unit 104 calculates the amount of expansion and contraction in the axial direction of the tire valve 30 using the first strain information 80 and the second strain information 82 included in the wheel state information 74 of the received unit data 70, and calculates It is determined whether or not an air leak has occurred in the tire by determining whether or not the amount of elongation in the axial direction of the tire valve is less than or equal to a predetermined value. The predetermined value of the amount of elongation in the axial direction of the tire valve is a value obtained in advance by experiments as the amount of elongation in the axial direction of the tire valve when air leakage occurs in the tire or when the possibility is high. When it is determined that an air leak has occurred, the display control unit 112 displays that effect on the display 20. Therefore, the display control unit 112 and the display 20 function as an air leak notification unit that notifies a vehicle occupant that an air leak has occurred.

  At this time, the air leak determination unit 104 specifies the unit ID 72 included in the unit data 70 including the first distortion information 80 and the second distortion information 82 that is the basis for determining that the air leak has occurred. Next, the air leak determination unit 104 refers to the correspondence relationship between the unit ID 72 stored in the storage unit 114 and the mounting wheels of the TPMS valve unit 16 and identifies the mounting position of the TPMS valve unit 16 that has transmitted the unit data 70. As a result, the wheel 14 determined to have air leakage is identified. The display control unit 112 causes the display 20 to display the wheel 14 that has been determined that the air leak has occurred, together with the fact that the air leak has occurred. As a result, the vehicle occupant can easily know which wheel 14 is causing air leakage.

  In the present embodiment, the expansion / contraction amount of the tire valve 30 refers to the distortion of the radially outer portion of the air supply hole 30a detected by the first strain sensor 56 and the air supply hole 30a detected by the second strain sensor 58. It means the average value of distortion in the radially inner part. Since the centrifugal force is applied to the TPMS valve unit 16 and other external force may be applied while the vehicle is traveling, the first distortion information 80 included in the wheel state information 74 of the received unit data 70 is also present. Further, the amount of expansion and contraction in the axial direction of the tire valve 30 may be calculated using information detected while the vehicle is stopped among the second distortion information 82. Further, the difference between the distortion of the radially outer portion of the air supply hole 30a detected by the first strain sensor 56 and the distortion of the radially inner portion of the air supply hole 30a detected by the second strain sensor 58 is a predetermined value. In the case where it is smaller than the above, the first and second strain information 80 and the second strain information 82 may be used to calculate the amount of expansion and contraction of the tire valve 30 in the axial direction. However, it goes without saying that the amount of expansion and contraction of the tire valve 30 is not limited to this value.

  When a bending force is applied to the tire valve, the grommet 32 is deformed and the function of shielding the inside and outside of the tire chamber 26 is weakened, so that tire air leakage is more likely to occur. For this reason, the air leak determination unit 104 calculates the radial bending amount of the tire valve 30 using the first strain information 80 and the second strain information 82, and according to the calculated radial bending amount of the tire valve 30. Thus, the threshold value of the amount of elongation in the axial direction of the tire valve 30 when determining whether or not air leakage has occurred is changed. The storage unit 114 stores a map in which the radial bending amount of the tire valve 30 and the threshold value of the elongation amount of the tire valve 30 used when determining air leakage are associated with each other. The air leak determination unit 104 changes the threshold according to the radial bending amount of the tire valve 30 by referring to this map.

  In the present embodiment, the radial bending amount of the tire valve 30 refers to the distortion of the radially outer portion of the air supply hole 30 a detected by the first strain sensor 56 and the air supply hole detected by the second strain sensor 58. It means the difference in distortion of the radially inner part of 30a. However, it goes without saying that the radial bending amount of the tire valve 30 is not limited to this value.

  When the display control unit 112 determines that the tire air pressure has decreased to a predetermined value or less and determines that air leakage has occurred in the tire, the tire air pressure has decreased due to tire air leakage. Is displayed on the display 20. Further, the display control unit 112 determines that the tire air pressure has decreased due to factors other than tire air leakage when it is determined that the tire air pressure has decreased to a predetermined value or less, and it has been determined that no air leakage has occurred in the tire. It is displayed on the display 20 that it has decreased. As a result, the vehicle occupant can take appropriate measures in accordance with the cause of the decrease in tire air pressure.

  The wheel speed estimation unit 106 calculates the radial bending amount of the tire valve 30 from the first strain information 80 and the second strain information 82, and uses the calculated radial bending amount of the tire valve 30 to rotate the wheel 14. Is estimated.

  The storage unit 114 stores wheel speed information indicating the estimated wheel speed in association with the time at which the wheel speed is estimated. Further, the storage unit 114 stores the tire pressure information 76 in association with the detection timing information 84. The tire durability determination unit 108 is configured to determine whether the wheel speed information from the past to the present stored in the storage unit 114 and the tire pressure information 76 received from the past to the present are related to tire durability. It is determined whether or not the above condition is satisfied.

  In the present embodiment, run-flat tires are employed for the wheels 14, and the vehicle 10 can travel a certain distance even when the air pressure of the wheels 14 decreases to some extent. For this reason, the tire durability determination unit 108 calculates the distance traveled by the vehicle 10 up to the present after the tire air pressure drops below a predetermined value using the wheel speed information stored in the storage unit 114. The tire durability determination unit 108 determines whether or not the distance traveled by the vehicle 10 has become equal to or greater than a predetermined distance after the tire air pressure has decreased below a predetermined value.

  When it is determined that the distance traveled by the vehicle 10 has become equal to or greater than the predetermined distance, the display control unit 112 indicates that the durability of the tire 24 has decreased and it is difficult for the vehicle 10 to travel further or the vehicle 10 travels. The remaining distance determined to be possible is displayed on the display 20. Therefore, the display control unit 112 and the display 20 also function as tire durability notification means for notifying the vehicle occupant that the durability of the tire 24 has decreased.

  The tire damage determination unit 110 first calculates the radial bending amount of the tire valve 30 from the first strain information 80 and the second strain information 82, and is given to the wheel using the calculated radial bending amount of the tire valve. Estimate external force. Next, the tire damage determination unit 110 determines whether or not the estimated external force satisfies a predetermined condition related to the damage of the tire 24.

  Specifically, tire damage determination unit 110 determines whether or not the estimated external force exceeds a predetermined value. When a very large external force is applied to the tire 24 at a time, such as when the wheel 14 rides on a large convex portion at a high speed, the tire 24 may be damaged. For this reason, if the estimated external force exceeds a predetermined value, there is a possibility that the tire 24 has been damaged. Therefore, the display control unit 112 may or may not indicate that the tire 24 has been damaged. A message to that effect is displayed on the display 20, and the vehicle occupant is notified.

  In addition, when a part of the tire 24 is already damaged, vibrations peculiar to the wheels 14 may occur while the vehicle 10 is traveling. Therefore, the tire damage determination unit 110 determines whether or not the tire 24 is damaged by determining whether or not the estimated external force corresponds to such a specific vibration. When it is determined that the tire is damaged, the display control unit 112 causes the display control unit 112 to display on the display 20 that the tire 24 has been damaged, and notifies the vehicle occupant of the fact. .

  At this time, the tire damage determination unit 110 specifies the unit ID 72 included in the unit data 70 including the first distortion information 80 and the second distortion information 82 that are the basis for determining that the tire is damaged. Next, the tire damage determination unit 110 refers to the correspondence relationship between the unit ID 72 stored in the storage unit 114 and the mounting wheels of the TPMS valve unit 16, and specifies the mounting position of the TPMS valve unit 16 that has transmitted the unit data 70. Thus, the wheel 14 determined that the tire is damaged is identified. The display control unit 112 causes the display 20 to display the wheel 14 that has been determined that the tire is damaged along with the fact that the tire is damaged. Thereby, the vehicle occupant can easily know which wheel 14 tire is damaged.

  In this way, the display control unit 112 also functions as a tire damage notification unit that notifies the vehicle occupant that the tire 24 has been damaged. As a result, the vehicle occupant can quickly take appropriate measures when the tire 24 is damaged.

  The present invention is not limited to the above-described embodiment, and an appropriate combination of the elements of the embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can be included in the scope of the present invention. Here are some examples.

  In a certain modification, a third strain sensor and a fourth strain sensor are respectively attached to both ends of the inner wall of the tire valve 30 in the circumferential direction of the wheel. For example, in FIG. 3, the third strain sensor is attached to the upper inner wall of the air supply hole 30a, and the fourth strain sensor is attached to the lower inner wall of the air supply hole 30a. As the third strain sensor and the fourth strain sensor, a general strain gauge that detects strain in one direction is employed. The third strain sensor and the fourth strain sensor are attached to the inner wall of the air supply hole 30a so as to face each other at the same position in the wheel radial direction, that is, face the wheel circumferential direction. Detect direction distortion.

  The third strain sensor and the fourth strain sensor are connected to the processing device 60, and each detection result is output to the processing device 60. The processing device 60 includes the third strain information acquired from the third strain sensor and the fourth strain information acquired from the fourth strain sensor in the wheel state information 74 of the unit data 70. The air leak determination unit 104 uses the third strain information and the fourth strain information to calculate a circumferential bend amount that is a bend amount of the tire valve 30 when the unit main body portion 28 is displaced in the wheel circumferential direction, In accordance with the calculated amount of bending of the tire valve 30 in the circumferential direction, the threshold value of the amount of elongation in the axial direction of the tire valve 30 when determining whether or not air leakage has occurred is changed. As a result, it is possible to realize a highly accurate air leak determination in consideration of the circumferential bending amount of the tire valve 30.

  In another modification, the first strain sensor 56 and the second strain sensor 58 are not cross-gauges, but employ general strain gauges that detect strain in one direction. The first strain sensor 56 and the second strain sensor 58 are arranged on the inner wall of the air supply hole 30a so as to detect the strain in the axial direction of the tire valve 30, respectively. As a result, an increase in cost due to the provision of the first strain sensor 56 and the second strain sensor 58 can be suppressed.

  In another modification, a warning light or the like is used instead of the display 20. In this case, an air pressure warning light for informing that the air pressure has decreased, an air leakage warning light for informing that air leakage has occurred in the tire, and a tire durability warning light for informing that the durability of the tire 24 has decreased. Tire damage warning lights for notifying that the tire has been damaged are provided on the instrument panels in the vehicle compartment.

  The display control unit 112 turns on the air pressure warning light when it is determined that the tire air pressure has dropped below a predetermined value. Further, the display control unit 112 turns on an air leak warning light when it is determined that an air leak has occurred in the tire 24. Moreover, the display control part 112 lights a tire durability warning lamp, when it determines with the durability of a tire having fallen. The display control unit 112 turns on a tire damage warning light when it is determined that the tire 24 has been damaged. Even when the warning light is used as described above, various warnings can be notified to the vehicle occupant.

  In another modification, a speaker (not shown) is provided in the vehicle 10. The ECU 100 has a voice control unit. The sound control unit determines that the tire air pressure has decreased to a predetermined value or less, determines that air leakage has occurred in the tire 24, determines that the durability of the tire has decreased, or the tire When it is determined that damage has been given to 24, a message to that effect is output from the speaker. In this way, various warnings can be notified to the vehicle occupant also by voice.

  In another modification, the ECU 100 includes an air leakage risk determination unit. The air leakage risk determination unit calculates the amount of expansion and contraction in the axial direction of the tire valve 30 using the first strain information 80 and the second strain information 82 included in the wheel state information 74 of the received unit data 70, By determining whether or not the calculated axial extension of the tire valve is equal to or less than a predetermined value, the risk of air leakage in the tire is determined. In this case, the risk of occurrence of air leakage in the tire means the fastening strength of the tire valve in a state before the air leakage occurs in the tire.

  Preferably, tire air leakage is predictable before it occurs. On the other hand, if the tire valve fastening is weak, even if there is no tire air leakage at that time, the tire valve fastening may become weaker thereafter, causing the tire air leakage. Becomes higher. For this reason, by detecting the fastening strength of the tire valve, that is, the amount of elongation in the axial direction, it is considered that the risk of air leakage occurring in the tire can be predicted in advance before the tire air leakage occurs.

  The risk of air leakage in the tire is divided into a plurality of ranks, for example, large or small. The predetermined value of the amount of elongation of the tire valve in the axial direction for determining the risk of occurrence of air leakage has passed a certain period of time while maintaining the fastening strength of the tire valve at the amount of elongation, or This is a value obtained in advance by experiments as a value that increases the possibility of air leakage in the tire when the vehicle travels a certain distance.

  For example, the air leakage risk determination unit has determined that there is a high possibility of air leakage because the tire valve axial extension amount is less than or equal to a predetermined value and the tire valve fastening is weak. In this case, the display control unit 112 displays that effect on the display 20. Therefore, the display control unit 112 and the display 20 function as an air leakage risk notification unit that notifies the vehicle occupant of the risk of air leakage. Thus, by notifying the vehicle occupant in advance of the risk of air leakage occurring in the tire based on the amount of expansion of the tire valve, it is possible to easily suppress tire air leakage.

  In another modification, the ECU 100 includes a valve fixing determination unit that determines the degree of fixing of the tire valve 30 to the wheel rim 22a. The valve fixing determination unit calculates the amount of expansion and contraction in the axial direction of the tire valve 30 using the first strain information 80 and the second strain information 82 included in the wheel state information 74 of the received unit data 70, and is calculated. The degree of fixation of the tire valve 30 to the wheel rim 22a is determined by determining whether or not the amount of elongation in the axial direction of the tire valve is equal to or less than a predetermined value. The degree of fixing of the tire valve 30 to the wheel rim 22a in this case means whether the tire valve 30 is fastened to the wheel rim 22a with a predetermined fastening strength.

  For example, when the valve fixing determination unit determines that the tire valve axial extension amount is equal to or less than a predetermined value and the tire valve is not sufficiently fastened, the display control unit 112 displays the fact on the display 20. . Accordingly, the display control unit 112 and the display 20 function as a valve fixing notification unit that notifies a vehicle occupant that the tire valve is not sufficiently fastened. In this way, by notifying the vehicle occupant in advance of the tire valve engagement status based on the amount of tire valve elongation, the tire valve engagement is gradually lowered due to insufficient engagement of the tire valve, and the tire air Leakage can be easily suppressed.

1 is an overall configuration diagram of a vehicle equipped with a tire pressure monitoring system according to an embodiment. It is sectional drawing of the wheel containing the TPMS valve unit which concerns on this embodiment. FIG. 3 is a view of a TPMS valve unit viewed from a viewpoint P in FIG. 2. It is a functional block diagram of a TPMS valve unit. It is a figure which shows the structure of unit data. It is a functional block diagram of the component mounted in a vehicle body among the components of a tire pressure monitoring system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Vehicle, 12 Car body, 14 Wheel, 16 TPMS valve unit, 20 Display, 22 Wheel, 22a Wheel rim, 22b Valve insertion hole, 24 Tire, 26 Tire air chamber, 28 Unit main-body part, 30 Tire valve, 30a Air supply hole , 52 Air pressure sensor, 54 Temperature sensor, 56 First strain sensor, 58 Second strain sensor, 100 ECU, 102 Tire air pressure determination unit, 104 Air leak determination unit, 106 Wheel speed estimation unit, 108 Tire durability determination unit, 110 Tire damage determination unit, 112 display control unit, 114 storage unit, 200 tire pressure monitoring system.

Claims (16)

In a wheel state detection device including a tire state and a unit body portion fixed to one end of the tire valve, and including a wheel state detection unit attached to the wheel by fixing the tire valve to the wheel rim,
The wheel state detection unit includes a valve deformation sensor for detecting an axial expansion / contraction amount of the tire valve. The wheel state detection unit is configured such that a tire valve is inserted into a valve insertion hole that connects a tire chamber and an outside provided in a wheel rim, and is fastened to the wheel rim so that the valve insertion hole is shielded. It can be attached to
An air leak determination means for determining whether or not an air leak has occurred in the tire by determining whether or not the detected axial extension of the tire valve is equal to or less than a predetermined threshold;
When it is determined that an air leak has occurred, an air leak notification means for notifying the passenger of the vehicle to that effect,
The wheel state detection device according to claim 1, further comprising: An air pressure sensor for detecting tire pressure;
Tire pressure determination means for determining whether or not the detected tire pressure has dropped below a predetermined value;
When it is determined that the detected tire air pressure has decreased to a predetermined value or less, the air pressure lowering informing means for informing the passenger of the vehicle to that effect is further provided,
The air pressure decrease notifying means determines that the tire air pressure has decreased to a predetermined value or less, and if it is determined that air leakage has occurred in the tire, the tire air pressure has decreased due to tire air leakage. The wheel state detection device according to claim 2, which notifies the effect.   The wheel state according to any one of claims 1 to 3, wherein the valve deformation sensor also detects a radial bending amount that is a bending amount of a tire valve when the unit main body portion is displaced in the wheel radial direction. Detection device.   The valve deformation sensor detects the axial distortion of the outer portion of the wheel diameter and the axial distortion of the inner portion of the wheel diameter on the inner peripheral surface of the air supply hole of the tire valve, thereby expanding and contracting the tire valve in the axial direction. The wheel state detection device according to claim 4, wherein the amount and a radial bending amount of the tire valve are detected. The wheel state detection unit is configured such that a tire valve is inserted into a valve insertion hole that connects a tire chamber and an outside provided in a wheel rim, and is fastened to the wheel rim so that the valve insertion hole is shielded. It can be attached to
An air leak determination means for determining whether or not an air leak has occurred in the tire by determining whether or not the detected axial extension of the tire valve is equal to or less than a predetermined threshold;
When it is determined that an air leak has occurred, air leak notification means for notifying the vehicle occupant to that effect, further comprising:
The air leakage determination means changes a threshold value of an expansion / contraction amount in the axial direction of the tire valve when determining whether or not air leakage has occurred in the tire according to the detected radial bending amount of the tire valve. The wheel state detection device according to any one of claims 4 and 5.   The wheel state detection device according to any one of claims 4 to 6, further comprising a wheel speed estimation unit that estimates a rotation speed of the wheel by using the detected radial bending amount of the tire valve. The wheel state detection unit further includes a tire pressure sensor for detecting tire pressure,
Tire durability that determines whether the tire pressure detected from the past to the present and the wheel rotational speed estimated from the past to the present satisfy a predetermined condition related to the durability of the tire Sex determination means;
When it is determined that the tire pressure detected from the past to the present and the rotational speed of the wheel estimated from the past to the present satisfy the predetermined condition, the tire durability is reduced. Tire durability notification means for informing the vehicle occupant of the vehicle,
The wheel state detection device according to claim 7, further comprising: Tire damage determination means for estimating the external force applied to the wheel using the detected radial bending amount of the tire valve and determining whether the estimated external force satisfies a predetermined condition related to tire damage When,
An external force notification means for notifying a vehicle occupant that the tire has been damaged when it is determined that the estimated external force satisfies the predetermined condition;
The wheel state detection device according to claim 4, further comprising: In a wheel state detection device including a tire state and a unit body portion fixed to one end of the tire valve, and including a wheel state detection unit attached to the wheel by fixing the tire valve to the wheel rim,
The wheel state detection unit includes a valve deformation sensor that detects a radial bending amount that is a bending amount of a tire valve when the unit main body portion is displaced in the wheel radial direction.   The valve deformation sensor detects a radial bending amount of the tire valve by detecting an axial distortion of the outer portion of the wheel diameter and an axial distortion of the inner portion of the wheel diameter of the inner peripheral surface of the air supply hole of the tire valve. The wheel state detection device according to claim 10, wherein   The wheel state detection device according to claim 10, further comprising a wheel speed estimation unit that estimates a rotation speed of the wheel by using the detected radial bending amount of the tire valve. The wheel state detection unit further includes a tire pressure sensor for detecting tire pressure,
Tire durability that determines whether the tire pressure detected from the past to the present and the wheel rotational speed estimated from the past to the present satisfy a predetermined condition related to the durability of the tire Sex determination means;
When it is determined that the tire pressure detected from the past to the present and the rotational speed of the wheel estimated from the past to the present satisfy the predetermined condition, the tire durability is reduced. Tire durability notification means for informing the vehicle occupant of the vehicle,
The wheel state detection device according to claim 12, further comprising: Tire damage determination means for estimating the external force applied to the wheel by using the detected radial bending amount of the tire valve, and determining whether the estimated external force satisfies a predetermined condition related to tire damage When,
An external force notification means for notifying a vehicle occupant that the tire has been damaged when it is determined that the estimated external force satisfies the predetermined condition;
The wheel state detection device according to claim 10, further comprising: The wheel state detection unit is configured such that a tire valve is inserted into a valve insertion hole that connects a tire chamber and an outside provided in a wheel rim, and is fastened to the wheel rim so that the valve insertion hole is shielded. It can be attached to
An air leakage risk determination means for determining a risk of air leakage in the tire by determining whether or not the detected axial extension of the tire valve is equal to or less than a predetermined threshold;
When it is determined that an air leak has occurred, an air leak risk notification means for notifying the passenger of the vehicle to that effect,
The wheel state detection device according to claim 1, further comprising: A wheel state detection unit having a tire body and a unit main body fixed to one end of the tire valve, and being attached to a wheel by fixing the tire valve to a wheel rim,
An air pressure sensor for detecting tire pressure;
A valve deformation sensor that detects the amount of expansion and contraction of the tire valve in the axial direction;
A wheel state detection unit comprising: data indicating the detected tire pressure; and transmitting means for wirelessly transmitting data indicating the detected amount of expansion and contraction of the tire valve in the axial direction;
Receiving means for receiving data transmitted by the transmitting means;
Using the data indicating the received tire pressure, tire pressure determination means for determining whether the tire pressure has dropped below a predetermined value;
Using the received data indicating the amount of expansion and contraction of the tire valve in the axial direction, it is determined whether or not the detected amount of axial expansion of the tire valve is equal to or less than a predetermined threshold value. Air leakage determination means for determining whether or not,
When it is determined that the tire air pressure has decreased to a predetermined value or less, the air pressure decrease informing means for informing the vehicle occupant to that effect,
When it is determined that an air leak has occurred in the tire, an air leak notification means for notifying the passenger of the vehicle to that effect,
A wheel state detection device comprising:

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