JP2006264439A - Device and method for acquiring wheel state - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine with high accuracy whether or not a wheel including a run-flat tire is in a run-flat state. <P>SOLUTION: A wheel state acquiring device 100 is applicable to a vehicle 10 having a wheel 14 including a wheel 16 and a run-flat tire 18 enabling the run-flat travel when the air pressure is dropped, and comprises an acceleration sensor 23 to detect the vibrating state of the wheel 14, and a traveling condition determination unit 31 to determine whether or not the wheel 14 is in a run-flat state based on the detected value of the acceleration sensor 23. The acceleration sensor 23 is integrated with a TPMS valve 20. The TPMS valve 20 is mounted on the wheel 16 so that the vibration is amplified by the resonance with the wheel 14 when the wheel 14 is in a run-flat state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wheel state acquisition device and a wheel state acquisition method applied to a vehicle having a plurality of wheels including a wheel and a run-flat tire that enables run-flat traveling when air pressure decreases.

  In recent years, run-flat tires that enable emergency travel for a certain distance even when the tires are punctured and the tire air pressure is reduced while the vehicle is running are becoming popular. As such a run-flat tire, a tire with a reinforced sidewall, a tire with a core that supports a tire from which air has escaped, and the like are known. However, this type of run-flat tire is only capable of emergency travel, and for run-flat travel, which is a vehicle travel state with reduced air pressure, there is an upper limit for at least the maximum speed and continuous travel distance. Determined. For this reason, in vehicles equipped with run-flat tires, it is important to know whether the wheels are in a run-flat state.

As a technique for detecting a run-flat state, there is known a technique for detecting a vibration component of a run-flat tire and comparing the detected vibration component with a vibration component of a run-flat tire obtained during normal running. (For example, refer to Patent Document 1). Further, as this type of technology, there is also known a run flat tire including a core having an incision portion for generating lateral vibration during run flat traveling (see, for example, Patent Document 2). Furthermore, a measurement signal is obtained from the amount that changes with the angular velocity of the wheel, which is a variable of time, a feature amount of the dispersion of the measurement signal is calculated, and a run flat that issues an alarm when the feature amount satisfies a predetermined ratio A state detection method has also been proposed (see, for example, Patent Document 3). As a method for evaluating the durability of a system including a run-flat tire, for example, one described in Patent Document 4 is known.
JP 2004-161022 A JP-T-2001-524049 JP-T-2002-519239 JP-T-2004-504213

  However, as in the conventional example, even if the vibration of the wheel, that is, the vibration of the run-flat tire or its core is detected, the normal running state and the run-flat state cannot often be distinguished well. Each of the conventional examples has a problem in the detection accuracy of the run-flat state.

  Therefore, an object of the present invention is to provide a wheel state acquisition device and a wheel state acquisition method that can accurately determine whether or not a wheel including a run flat tire is in a run flat state.

  The wheel state acquisition device according to the present invention is applied to a vehicle having a plurality of wheels including a wheel and a run-flat tire that enables run-flat traveling when the air pressure decreases, and is used to acquire the state of each wheel. In the wheel state acquisition device, a vibration detection unit that is provided for each wheel and detects a vibration state of the corresponding wheel, and a determination unit that determines whether or not the wheel is in a run-flat state based on the detection value of each vibration detection unit The vibration detecting means is attached to the wheel so that the vibration is amplified by resonance with the wheel when the wheel is in a run-flat state.

  The wheel state acquisition device includes a determination unit that determines whether or not the wheel is in a run flat state based on a detection value of a vibration detection unit attached to the wheel including the wheel and the run flat tire. And the vibration detection means of this wheel state acquisition device is attached to the wheel so that when the wheel is in a run-flat state, the vibration is amplified by resonance with the wheel. As a result, the detection value of the vibration detection means changes clearly between the normal running state and the run-flat running state, so that the wheels are in the run-flat state by monitoring the detection value of the vibration detection means. It is possible to accurately determine whether or not.

  In this case, it is preferable that the attachment strength of the vibration detection means to the wheel is set so that the vibration of the vibration detection means is amplified by resonance with the wheel when the wheel is in a run-flat state.

  That is, the mounting strength of the vibration detecting unit with respect to the wheel can be easily adjusted by appropriately selecting the rigidity of a grommet or the like interposed in the mounting portion of the vibration detecting unit, for example. If the mounting strength is appropriately selected, the vibration of the vibration detecting means can be easily and reliably amplified by resonance with the wheel when the wheel is in a run-flat state.

  In addition, the wheel state acquisition device according to the present invention performs the run based on the detection value of the vibration detection unit and the run flat travel distance of the vehicle when the determination unit determines that at least one of the wheels is in the run flat state. It is preferable to further include a remaining life estimating means for estimating the remaining life of the run-flat tire in the flat state.

  The remaining life of the run-flat tire can be estimated from the load applied to the wheel during the run-flat running and the accumulated running distance after shifting to the run-flat running distance, that is, the run-flat running state. Moreover, in the wheel state acquisition device according to the present invention, it is possible to accurately determine whether or not the wheel is in a run-flat state as described above, so that the run-flat travel distance is accurately grasped and the vehicle is normal. Even after shifting from the running state to the run-flat running state, it is possible to acquire the load input to the wheels from the road surface based on the detection value of the vibration detecting means. Therefore, if such a remaining life estimation means is further provided in the wheel state acquisition device, the remaining life of the run-flat tire in the run-flat state is accurately estimated, and a warning or the like is generated for the driver based on the estimated remaining life. It becomes possible to do.

  Furthermore, it is preferable that the vibration detection means detects acceleration in the longitudinal direction of the wheel.

  In general, when the air pressure of a run-flat tire decreases, the rigidity in the longitudinal direction of the tire, that is, in the tire radial direction, changes significantly, and accordingly, the longitudinal component of the wheel vibration varies from the normal value. Therefore, it is possible to accurately determine whether or not the wheel is in a run-flat state by using vibration detection means capable of detecting acceleration in the longitudinal direction of the wheel and resonating the vibration detection means and the wheel in the vertical direction. Is possible.

  Further, the vibration detecting means may be capable of detecting acceleration in the lateral direction of the wheel.

  Thus, the lateral load applied to the wheel can be obtained by detecting the component in the lateral direction, that is, the width direction of the wheel, among the vibrations of the wheel. Accordingly, for example, if the remaining life of the run-flat tire is estimated in consideration of a lateral load applied to the wheel, it is possible to improve the estimation accuracy of the remaining life.

  Furthermore, the vibration detection means may be capable of detecting acceleration in the lateral direction of the wheel, and the wheel state acquisition device according to the present invention may detect when at least one of the wheels is in the run-flat state by the determination means. The second determination means for determining whether or not the acceleration in the lateral direction of the wheel detected by the vibration detection means exceeds a predetermined value, and the acceleration in the lateral direction of the wheel in the run-flat state by the second determination means. An alarm unit that generates a predetermined alarm when it is determined that the predetermined value is exceeded may be further provided.

  The wheel may be provided with an air pressure adjusting valve for a run-flat tire, and the vibration detecting means is preferably an acceleration sensor integrated with the air pressure adjusting valve.

  By adopting such a configuration, it is possible to easily secure a mass necessary for amplifying the vibration of the vibration detecting means by resonance with the wheel when the wheel is in a run-flat state without increasing the number of parts. Is possible.

  Another wheel state acquisition device according to the present invention is applied to a vehicle having wheels including a wheel and a run-flat tire that enables run-flat traveling when the air pressure decreases, and is used to acquire the state of each wheel. In the wheel state acquisition device, at least one of the wheels is determined by a first determination unit that determines whether or not the wheel is in a run-flat state, a detection unit that detects acceleration in the lateral direction of the wheel, and the first determination unit. Second determination means for determining whether or not the acceleration in the lateral direction of the wheel in the run-flat state detected by the vibration detection means exceeds a predetermined value when it is determined that the run-flat state exists. It is characterized by.

  Run-flat tires allow emergency travel for a certain distance even when tire pressure drops, but are in a run-flat state when the emergency run is continued while tire pressure is reduced. There is also a risk that the run-flat tire will come off the wheel. In such a case, the run-flat tire is separated from the wheel mainly by a force acting in the lateral direction with respect to the wheel. Therefore, if it is determined that at least one of the wheels is in the run-flat state, as in this wheel state acquisition device, if the acceleration in the lateral direction of the wheel in the run-flat state is monitored, it is in the run-flat state. It can be determined whether or not the run-flat tire may be detached from the wheel. As a result, when it is determined that the acceleration in the lateral direction of the wheel in the run-flat state exceeds a predetermined value, for example, a predetermined alarm is generated to prevent the run-flat tire from coming off the wheel. It is possible to suppress the run-flat running state from continuing beyond the limit.

  The wheel state acquisition method according to the present invention is applied to a vehicle having a plurality of wheels including a wheel and a run-flat tire that enables run-flat traveling when the air pressure decreases, and is used to acquire the state of each wheel. In the wheel state acquisition method, the vibration detection means for detecting the vibration of the wheel is attached to the wheel so that the vibration is amplified by resonance with the wheel when the wheel is in the run-flat state, and the vibration detection means is detected. It is characterized by determining whether a wheel is in a run-flat state based on a value.

  Another wheel state acquisition method according to the present invention is applied to a vehicle having a plurality of wheels including a wheel and a run-flat tire that enables a run-flat running when the air pressure is reduced, in order to acquire the state of each wheel. In the wheel state acquisition method used, when it is determined that at least one of the plurality of wheels is in the run-flat state, the lateral acceleration of the wheel in the run-flat state is detected, and It is determined whether or not the acceleration in the direction exceeds a predetermined value.

  According to the present invention, it is possible to accurately determine whether or not a wheel including a run-flat tire is in a run-flat state.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating a main part of a vehicle including a wheel state acquisition device according to the present invention, and FIG. 2 is a partial cross-sectional view illustrating wheels provided in the vehicle of FIG. A vehicle 10 shown in FIG. 1 includes four wheels 14 provided on a vehicle body 12, a steering device (not shown) that steers steering wheels among these four wheels 14, and among these four wheels 14. A driving drive source (not shown) for driving the driving wheels is provided. Each wheel 14 includes a wheel 16 and a run flat tire 18.

  The run flat tire 18 employed in the vehicle 10 of the present embodiment is a so-called side-reinforced run flat tire, and enables run flat running when the air pressure decreases. As shown in FIG. 2, the run-flat tire 18 includes a pair of bead portions 181 in which a bead core 180 is embedded, a pair of sidewall portions 182 that extend outward from the bead portion 181 in the tire radial direction, and both sidewall portions 182. And a tread portion 183 extending therebetween. A carcass 184 made of, for example, a single fiber material is embedded in the pair of bead portions 181, the pair of sidewall portions 182 and the tread portion 183, and the tread portion 183 is positioned outside the carcass 184. A belt layer 185 is embedded. Reinforcing rubber 187 is embedded in each sidewall portion 182 so as to be located inside the inner liner 186.

  Each reinforcing rubber 187 has high rigidity, and when the air pressure in the tire internal space 188 defined by the wheel 16 and the run-flat tire 18 decreases due to puncture or the like, the entire tire 18 is made to the wheel 16. Support, thereby enabling run-flat travel. The run flat tire 18 provided in the vehicle 10 is not limited to the side reinforcement type, and a core that supports the entire tire 18 with respect to the wheel 16 when the air pressure in the tire internal space 188 decreases. It may be of the core type provided. Further, a driving type or a pasting type balance weight 17 is appropriately attached to the wheel 16.

  Furthermore, a TPMS valve 20 that functions as a valve for adjusting the air pressure of the run-flat tire 18 is attached to each wheel 14 described above. Each TPMS valve 20 is attached to a mounting hole 16b provided in the wheel rim 16a of the wheel 16 via a grommet 19 made of elastic rubber, a washer, and a bolt. The grommet 19 has a predetermined rigidity and keeps the tire internal space 188 airtight. Further, the valve cap 20a of the TPMS valve 20 protrudes to the outside of the wheel rim 16a. If the valve cap 20a is removed and a hose of an air supply device is connected to a valve port (not shown), the tire inner space 188 is formed. Air can be supplied.

  As shown in FIG. 2, each TPMS valve 20 has a housing 21 that protrudes into the tire internal space 188. In the housing 21, an air pressure sensor 22 that detects the air pressure in the tire internal space 188, an acceleration sensor (G sensor) 23 that detects the acceleration of the housing 21, that is, the wheel 14, and the air pressure and acceleration detected by the sensors 22 and 23. A wheel-side communication device 24 that wirelessly transmits a signal indicating the detected value of the vehicle and a power source (battery) (not shown) for supplying electric power to these sensors 22, 23 and the wheel-side communication device 24 are accommodated.

  In the present embodiment, for example, a semiconductor pressure sensor is employed as the air pressure sensor 22. As the acceleration sensor 23, a so-called biaxial acceleration sensor is used. The acceleration sensor 23 is an acceleration in the longitudinal direction of the wheel 14, that is, the radial direction of the wheel 14, and the lateral direction of the wheel 14, that is, the width direction of the wheel 14. The acceleration at can be detected. The wheel side communication device 24 can wirelessly transmit the detection values of the sensors 22 and 23 in the housing 21 at intervals of 15 to 60 seconds, for example.

  Note that the wheel side communication device 24 transmits the detection values of the sensors 22 and 23 in association with each other. In the present embodiment, all of the detection values of the sensors 22 and 23 included in the TPMS valve 20 are included in the radio signal for each transmission, whereby the detection values of the sensors 22 and 23 are associated with each other. . Further, a temperature sensor that detects the temperature of air in the tire internal space 188 may be further disposed in the housing 21 of the TPMS valve 20.

  On the other hand, as shown in FIG. 1, the vehicle body 12 of the vehicle 10 has an electronic control unit (hereinafter referred to as “ECU”) that performs various controls using information transmitted from the wheel side communication device 24 of the TPMS valve 20. 30 is mounted. The ECU 30 includes 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, an input / output interface, a memory, and the like. As shown in FIG. 1, a vehicle body side communication device 25, a sensor group 26, and an alarm device 27 are connected to the ECU 30.

  The vehicle body side communication device 25 transmits and receives signals to and from the wheel side communication device 24 housed in the housing 21 of the TPMS valve 20 of each wheel 14, and is a signal wirelessly transmitted from the wheel side communication device 24. Is given to the ECU 30. The sensor group 26 includes, for example, a wheel speed sensor (not shown) that is provided for each wheel 14 and detects the speed of the corresponding wheel 14. The warning device 27 issues a warning to the driver under a predetermined condition under the control of the ECU 30, and includes, for example, a warning display device provided on the instrument panel of the vehicle 10.

  The above-described vehicle 10 is equipped with a run-flat tire 18 that allows an emergency run for a certain distance even if the tire air pressure decreases due to puncture or the like. In the vehicle 10, it is important to know whether or not the vehicle 10 is running on a run flat.

  Here, when the air pressure of the run-flat tire 18 decreases due to puncture or the like, and the run-flat tire 18 is supported by the reinforcing rubber 187 of each sidewall portion 182 so that the run-flat tire 18 is supported by the wheel 16, the run-flat tire 18 The rigidity in the vertical direction (radial direction) is increased, and the frequency of vibration in the vertical direction (wheel radial direction) input to the acceleration sensor 23 via the run-flat tire 18 is approximately close to the predetermined value fx. On the other hand, the acceleration sensor 23 housed in the housing 21 of each TPMS valve 20 basically vibrates in synchronization with the wheel 14, but the vibration of the acceleration sensor 23 itself is longitudinally caused by resonance with the wheel 14. If amplified, as shown in FIG. 3, the value of the longitudinal acceleration of the wheel 14 output by the acceleration sensor 23 becomes significantly larger than that during normal running.

  In view of such a point, in each wheel 14 of the vehicle 10, the acceleration sensor 23 serving as a vibration detection means is applied to the wheel 14 so that the vibration is amplified in the vertical direction by resonance with the wheel during run-flat traveling. It is attached to. That is, in the present embodiment, since the acceleration sensor 23 as the vibration detecting means is housed in the housing 21 of the TPMS valve 20, the natural frequency of the housing 21 housing the acceleration sensor 23 is the above-described value fx, that is, When the wheel 14 is in the run-flat state, it is set so as to substantially coincide with the vibration frequency fx in the longitudinal direction (wheel radial direction) input to the acceleration sensor 23 via the tire 18.

  In this case, the attachment strength of the housing 21, that is, the acceleration sensor 23 to the wheel 14, that is, the wheel 16 is mainly defined by the rigidity of the grommet 19. Therefore, in the present embodiment, the vibration frequency fx in the longitudinal direction (wheel radial direction) input to the acceleration sensor 23 via the tire 18 when the wheel 14 is in a run-flat state is obtained experimentally and analytically. Thus, the rigidity and the like of the grommet 19 are determined so that the natural frequency of the housing 21 becomes the above-described value fx according to the weight, size, and the like of the TPMS valve 20.

  This makes it possible to easily and reliably amplify vibration in the longitudinal direction of the acceleration sensor 23 by causing the wheel 14 and the housing 21 to resonate in the longitudinal direction during run-flat traveling, and the wheel 14 detected by the acceleration sensor 23. The vertical acceleration can be clearly changed between a normal running state and a run-flat running state. Therefore, by monitoring the longitudinal acceleration of the wheel 14 detected by the acceleration sensor 23, it is possible to accurately determine whether or not the vehicle is running on a run flat. Further, as in this embodiment, by integrating the acceleration sensor 23 as the vibration detecting means with the TPMS valve 20 functioning as the air pressure adjusting valve for the run-flat tire 18, without increasing the number of parts, It becomes possible to easily secure a mass necessary for amplifying the vibration of the acceleration sensor 23 by resonance with the wheel 14 during the run-flat traveling.

  The above-described ECU 30 is configured as shown in FIG. 4 so that it can detect well whether any of the wheels 14 is in the run-flat state based on the detection value of the acceleration sensor 23 in the housing 21 of the TPMS valve 20. have. FIG. 4 is a control block diagram illustrating a configuration related to detection of a run-flat running state in the vehicle 10. As shown in the figure, the ECU 30 is constructed with a traveling state determination unit 31, a traveling distance calculation unit 32, a lateral G determination unit 33, and a remaining life estimation determination unit 34. A wheel state acquisition device 100 according to the present invention is constituted by the acceleration sensor 23 and the like. In FIG. 3, only one TPMS valve 20 is shown for simplicity.

  The traveling state determination unit 31 is stored in the detected value of the acceleration in the longitudinal direction of the wheel 14 among the detected values of the acceleration sensor 23 received from each TPMS valve 20 via the vehicle body side communication device 25, and in a memory (not shown) or the like. It is determined whether any of the wheels 14 is in a run-flat state based on the threshold value. And the driving | running | working state determination part 31 gives a command signal to the alarm device 27 in order to generate an alarm according to the determination result. Further, when the traveling state determination unit 31 determines that any of the wheels 14 is in the run-flat state, the traveling distance calculation unit 32 uses, for example, the detection value of the wheel speed sensor of each wheel 14 included in the sensor group 26. Based on this, the run-flat travel distance of the vehicle 10, that is, the cumulative travel distance after any of the wheels 14 is in the run-flat state and the vehicle 10 is shifted from the normal travel state to the run-flat travel state is calculated.

  The lateral G determination unit 33 stores the detected value of the lateral acceleration in the width direction of the wheel 14 among the detected values of the acceleration sensor 23 received from each TPMS valve 20 via the vehicle body side communication device 25, and a memory (not shown). It is determined whether or not the run-flat tire 18 may be detached from the wheel rim 16a in the wheel 14 in the run-flat state based on the threshold value. The lateral G determination unit 33 also gives a command signal to the alarm device 27 to generate an alarm according to the determination result.

  Further, the vehicle 10 of the present embodiment includes a vehicle stability control device (VSC) that controls a brake unit and a travel drive source (not shown) so as to ensure the stability in the turning direction of the vehicle 10. The lateral G determination unit 33 is connected to an electronic control unit (hereinafter referred to as “VSCUCU”) 40 of the vehicle stability control device. Then, the lateral G determination unit 33 gives a command signal to the VSC ECU 40 so as to control the brake unit and the travel drive source so that the travel stability of the vehicle 10 is ensured according to the determination result.

  The remaining life estimation determination unit 34 receives the acceleration sensor 23 received from each TPMS valve 20 via the vehicle body side communication device 25 when the traveling state determination unit 31 determines that any of the wheels 14 is in the run-flat state. And the remaining life of the run-flat tire 18 in the run-flat state is estimated according to a predetermined calculation algorithm stored in a memory (not shown). The remaining life estimation determination unit 34 gives a command signal to the alarm device 27 to generate an alarm according to the determination result, and controls the brake unit and the travel drive source so that the travel stability of the vehicle 10 is ensured. In order to do so, a command signal is given to the VSC ECU 40.

  The travel state determination unit 31, travel distance calculation unit 32, lateral G determination unit 33, and remaining life estimation determination unit 34 described above are functional blocks constructed by causing the CPU to execute a program. Needless to say, at least a part of the functional blocks can be constructed by hardware.

  Next, a procedure for detecting the wheels 14 in the run-flat state in the vehicle 10 will be described with reference to FIG.

  The routine shown in FIG. 5 is repeatedly executed at predetermined intervals by the ECU 30 while the vehicle 10 is traveling. At the execution timing of this routine, the ECU 30 acquires the detection value of the acceleration sensor 23 of the TPMS valve 20 for each wheel 14 via the vehicle body side communication device 25 or the like (S10). In this case, the traveling state determination unit 31 of the ECU 30 receives the detection value of the vertical acceleration of the wheel 14 among the detection values of each acceleration sensor 23, and the vertical direction of the wheel 14 detected by the acceleration sensor 23 for each wheel 14. It is determined whether or not the deviation between the direction acceleration and the maximum value of the vertical acceleration of the wheel 14 during normal running obtained in advance exceeds a predetermined threshold (S12).

  Here, when the air pressure of the run-flat tire 18 decreases due to puncture or the like, generally, the rigidity in the longitudinal direction of the tire, that is, the radial direction of the tire significantly changes, and accordingly, the longitudinal component of the vibration of the wheel 14 is normal. Fluctuates from the value of. In the present embodiment, when any of the wheels 14 is in a run-flat state, the vibration in the longitudinal direction of the acceleration sensor 23 itself of the wheel 14 is amplified by resonance with the wheel 14 as described above. The value of the vertical acceleration of the wheel 14 output by the sensor 23 is significantly larger than that during normal running.

  Therefore, by comparing the longitudinal acceleration of the wheel 14 output by the acceleration sensor 23 with the maximum value of the longitudinal acceleration of the wheel 14 during normal running, which is obtained experimentally and analytically in advance, the wheel 14 It is possible to easily determine whether or not the vehicle is in a flat state. When the deviation does not exceed the threshold value in all the wheels 14, the traveling state determination unit 31 determines that the run-flat tires 18 of all the wheels 14 are normal (No in S12). In this case, the processing after S12 is not executed, and the processing after S10 is executed again.

  On the other hand, when the deviation exceeds the threshold value in any of the wheels 14, the traveling state determination unit 31 determines that any of the wheels 14 is in a run-flat state (Yes in S12). Then, the traveling state determination unit 31 specifies the wheel 14 in the run-flat state and gives a command signal to the alarm device 27 to notify the driver that the vehicle 10 is in the run-flat traveling state (S14). ). In the vehicle 10 of the present embodiment, for example, a blinking display indicating the wheels 14 in a run-flat state is performed in a predetermined display area provided on the instrument panel. In S14, the travel state determination unit 31 gives a command signal to the travel distance calculation unit 32 to start calculation of the run-flat travel distance, and a signal indicating the wheel 14 specified as being in the run-flat state. Is given to the lateral G determination unit 33.

  The lateral G determination unit 33 that has received the signal from the traveling state determination unit 31 acquires the detection value of the lateral acceleration of the wheel 14 among the detection values of the acceleration sensor 23 of the wheel 14 that are identified as being in the run-flat state. Then, for the wheel 14, it is determined whether or not the lateral and vertical acceleration of the wheel 14 detected by the acceleration sensor 23 exceeds a predetermined threshold value (S16). Here, the run-flat tire 18 enables emergency traveling for a certain distance even when the tire air pressure decreases. However, if the emergency traveling is continued in a state where the tire air pressure is reduced, the run flat tire 18 in the run flat state may be detached from the wheel 16. In such a case, the run flat tire 18 is separated from the wheel 16 mainly by a force acting in the lateral direction with respect to the wheel 14.

  Therefore, when it is determined that any of the wheels 14 is in the run-flat state, the run-flat tire 18 in the run-flat state is detached from the wheel 16 if the lateral acceleration of the wheel 14 in the run-flat state is monitored. It can be determined whether or not there is a risk of doing so. That is, when the lateral acceleration of the wheel 14 in the run-flat state exceeds a threshold value determined experimentally and analytically in advance, the run-flat tire 18 in the run-flat state may be detached from the wheel 16.

  For this reason, if the lateral G determination unit 33 determines that the lateral acceleration detected by the acceleration sensor 23 for the wheel 14 in the run-flat state exceeds a predetermined threshold value (Yes in S16), the lateral G determination unit 33 informs the driver. On the other hand, a command signal is given to the alarm device 27 to notify that the run-flat tire 18 in the run-flat state may be detached from the wheel 16, and a brake unit or the like is used to ensure the running stability of the vehicle 10. A command signal is given to the VSC ECU 40 to control the traveling drive source (S18).

  As described above, when it is determined that the acceleration in the lateral direction of the wheel 14 in the run-flat state is higher than the threshold value, a predetermined alarm is generated, so that the run-flat tire 18 in the run-flat state has the wheel 16. It is possible to prevent the run-flat running state from exceeding the limit and to prevent the vehicle from leaving the vehicle. Further, in the vehicle 10 of the present embodiment, when it is determined that the acceleration in the lateral direction of the wheel 14 in the run-flat state is higher than the threshold value, an alarm is generated and the vehicle stability control device performs the vehicle 10. The brake unit and the travel drive source are controlled so that the travel stability is ensured. Therefore, even if the run-flat running state is continued thereafter, it is possible to ensure the steering stability of the vehicle 10.

  On the other hand, when the lateral G determination unit 33 determines that the lateral acceleration of the wheel 14 in the run-flat state is equal to or less than a predetermined threshold (No in S16), the remaining life estimation determination unit 34 The remaining life of the run-flat tire 18 of the wheel 14 specified as being in the state is estimated and calculated (S20). When estimating the remaining life, the remaining life estimation determination unit 34 acquires the vertical acceleration and the lateral acceleration detected by the acceleration sensor 23 for the wheel 14 in the run-flat state, and from the travel distance calculation unit 32, the vehicle 10 run-flat travel distances, that is, the cumulative travel distance after any of the wheels 14 is in the run-flat state and the vehicle 10 is shifted from the normal travel state to the run-flat travel state.

  Then, the remaining life estimation determination unit 34 estimates and calculates the remaining life of the run-flat tire 18 in the run-flat state according to a calculation algorithm prepared in advance. In the vehicle 10 of the present embodiment, the run-flat tire 18 in the run-flat state with the longitudinal load and the lateral load applied to the wheel 14 in the run-flat state during travel and the flat travel distance as variables. A function for prescribing the remaining lifetime is determined in advance, and an arithmetic algorithm using the function is stored in a memory (not shown). The remaining life estimation determination unit 34 is applied to the wheel 14 in the run-flat state during traveling from the longitudinal acceleration and the lateral acceleration detected by the acceleration sensor 23 for the wheel 14 in the run-flat state. And the load in the lateral direction are calculated, and the remaining life of the run-flat tire 18 in the run-flat state is calculated using these loads, the run-flat travel distance, and the above function.

  As described above, in the vehicle 10 according to the present embodiment, it is possible to accurately determine whether or not the wheel 14 is in the run-flat state, so that the run-flat travel distance is accurately grasped and the vehicle 10 is normal. Even after shifting from the running state to the run-flat running state, it is possible to acquire the load input to the wheel 14 from the road surface based on the detection value of the acceleration sensor 23 provided on the wheel 14. Therefore, in S20, the remaining life estimation determination unit 34 accurately estimates and calculates the remaining life of the run-flat tire in the run-flat state. Further, if the remaining life of the run-flat tire 18 is estimated in consideration of the lateral load applied to the wheel 14 among the loads applied to the wheel 14 as in the present embodiment, the estimation accuracy of the remaining life is improved. It becomes possible to make it.

  When calculating the remaining life of the run-flat tire 18 of the wheel 14 in the run-flat state, the remaining life estimation determining unit 34 compares the calculated remaining life with a threshold value stored in a memory (not shown) or the like (S22). . The threshold value used in S22 is, for example, a value obtained by multiplying the life of the run flat tire 18 guaranteed by a tire manufacturer or the like by a predetermined coefficient (for example, 90%). When the remaining life estimation determination unit 34 determines that the calculated remaining life is below the threshold (Yes in S22), the run flat tire 18 in the run flat state with respect to the driver is approaching the use limit. A command signal is given to the alarm device 27 to notify the fact that it is present, and a command signal is given to the VSC ECU 40 to control the brake unit and the travel drive source so that the travel stability of the vehicle 10 is ensured (S18).

  Thus, by giving a warning to the driver when the run-flat tire 18 in the run-flat state is approaching the use limit, it is possible to prevent the run-flat running state from continuing beyond the limit. It becomes. Further, in the vehicle 10, even when the run flat tire 18 in the run flat state is approaching the use limit, the control of the brake unit and the travel drive source by the vehicle stability control device is started. Therefore, even if the run-flat running state is continued thereafter, it is possible to ensure the steering stability of the vehicle 10. If it is determined that the remaining life calculated by the remaining life estimation determination unit 34 is not less than the threshold value (No in S22), the processing after S10 is executed again.

It is a schematic block diagram which shows the principal part of the vehicle provided with the wheel state acquisition apparatus by this invention. It is a fragmentary sectional view which shows the wheel with which the vehicle of FIG. 1 was equipped. It is a graph for demonstrating the output characteristic of the acceleration sensor contained in the wheel state acquisition apparatus by this invention. It is a control block diagram which shows the wheel state acquisition apparatus by this invention. 2 is a flowchart for explaining a procedure for detecting wheels in a run-flat state in the vehicle of FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Vehicle, 12 Car body, 14 Wheel, 16 Wheel, 16a Wheel rim, 16b Mounting hole, 17 Balance weight, 18 Run flat tire, 19 Grommet, 20 TPMS valve, 20a Valve cap, 21 Housing, 22 Air pressure sensor, 23 Acceleration sensor 24 wheel side communicator, 25 vehicle body side communicator, 26 sensor group, 27 alarm device, 30 ECU, 31 travel state determination unit, 32 travel distance calculation unit, 33 lateral G determination unit, 34 remaining life estimation determination unit, 40 VSCUCU, 100 wheel state acquisition device, 180 bead core, 181 bead part, 182 sidewall part, 183 tread part, 184 carcass, 185 belt layer, 186 inner liner, 187 reinforcing rubber, 188 tire internal space.

Claims (10)

In a wheel state acquisition device that is applied to a vehicle having a plurality of wheels including a wheel and a run-flat tire that enables run-flat traveling when air pressure decreases, and used to acquire the state of each wheel,
Vibration detecting means provided for each wheel to detect the vibration state of the corresponding wheel;
Determination means for determining whether or not the wheel is in a run-flat state based on a detection value of each vibration detection means,
The wheel state acquisition device, wherein the vibration detection means is attached to the wheel so that the vibration is amplified by resonance with the wheel when the wheel is in a run-flat state.   The mounting strength of each of the vibration detection means with respect to the wheel is set so that vibration of the vibration detection means is amplified by resonance with the wheel when the wheel is in a run-flat state. The wheel state acquisition device according to claim 1.   A run-flat tire in a run-flat state based on a detection value of the vibration detection means and a run-flat travel distance of the vehicle when it is determined by the determination means that at least one of the wheels is in a run-flat state The wheel state acquisition device according to claim 1, further comprising a remaining life estimation unit that estimates the remaining life of the vehicle.   The wheel state acquisition device according to any one of claims 1 to 3, wherein the vibration detection unit detects acceleration in a longitudinal direction of the wheel.   The wheel state acquisition device according to claim 4, wherein the vibration detection unit can further detect acceleration in a lateral direction of the wheel. The vibration detection means can detect acceleration in the lateral direction of the wheel,
Whether or not the acceleration in the lateral direction of the wheel in the run-flat state detected by the vibration detection means exceeds a predetermined value when at least one of the wheels is determined to be in the run-flat state by the determination means A second determination means for determining;
And a warning means for generating a predetermined warning when it is determined by the second determination means that the acceleration in the lateral direction of the wheel in the run-flat state is higher than the predetermined value. The wheel state acquisition device according to any one of claims 1 to 4.   2. The wheel is provided with an air pressure adjusting valve for the run-flat tire, and the vibration detecting means is an acceleration sensor integrated with the air pressure adjusting valve. To 6. The wheel state acquisition device according to any one of items 1 to 6. In a wheel state acquisition device applied to a vehicle having a wheel and a wheel including a run flat tire that enables run flat running when the air pressure decreases, and used to acquire the state of each wheel,
First determination means for determining whether or not the wheel is in a run-flat state;
Detecting means for detecting acceleration in a lateral direction of the wheel;
When the first determination means determines that at least one of the wheels is in a run-flat state, the lateral acceleration of the wheel in the run-flat state detected by the vibration detection means exceeds a predetermined value. And a second determination means for determining whether or not there is a wheel state acquisition device. In a wheel state acquisition method that is applied to a vehicle having a plurality of wheels including a wheel and a run-flat tire that enables run-flat traveling when the air pressure decreases, and used to acquire the state of each wheel,
The vibration detection means for detecting the vibration of the wheel is attached to the wheel so that the vibration is amplified by resonance with the wheel when the wheel is in a run-flat state, and the detection value of the vibration detection means And determining whether the wheel is in a run-flat state based on the above. In a wheel state acquisition method that is applied to a vehicle having a plurality of wheels including a wheel and a run-flat tire that enables run-flat traveling when the air pressure decreases, and used to acquire the state of each wheel,
When it is determined that at least one of the plurality of wheels is in a run-flat state, acceleration in the lateral direction of the wheel in the run-flat state is detected, and the acceleration in the lateral direction has a predetermined value. It is determined whether it exceeds, The wheel state acquisition method characterized by the above-mentioned.

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