JP4207723B2 - Wheel state detection device - Google Patents

Description

  The present invention relates to a technique for detecting a state of a wheel, and more particularly to a wheel state detection device that detects a state of a wheel based on an output value of a sensor provided on the wheel.

  In order for the vehicle to travel safely, it is indispensable to keep the state of wheels including tires and wheels normal. When a strong impact from the road surface is applied to the tire or wheel during traveling, the tire is likely to swell, the wheel is deformed, and the fatigue strength is reduced. When a sudden abnormal deformation occurs, the user immediately notices the abnormality. However, when such a sudden abnormal deformation does not occur, the user hardly notices the abnormality. Therefore, it is necessary to accurately detect impacts on the tires and wheels, notify the driver of the abnormality, and prompt inspection.

Non-Patent Document 1 provides a sensor that measures the amount of rim deformation on the wheel rim of a tire, and determines that an excessive input to the tire and wheel has occurred and warns when the amount of rim deformation exceeds a threshold value. Is disclosed.
Katagiri Masaki, “Input Detection Control Device for Tire Assemblies”, Toyota Technical Disclosure, May 30, 2003, issue number 14787, p. 211-212

  The technique disclosed in Non-Patent Document 1 is a method of indirectly detecting the impact on the tire and the wheel by measuring the deformation amount of the wheel rim, and does not directly observe the action of the force due to the impact. It is easily affected by disturbances and it is difficult to accurately grasp the impact force. In order to increase the reliability of the tire, it is necessary to detect the impact force applied to the tire and the wheel more accurately and prompt the driver to check. In order for the dealer to perform an appropriate inspection, it is desirable to be able to accurately grasp the situation when an impact is applied to the tire or wheel.

  The present invention has been made in view of these points, and an object thereof is to provide a wheel state detection technique capable of accurately grasping an input of an impact to a wheel.

  An aspect of the present invention relates to a wheel state detection device that detects a wheel state based on an output value of a sensor provided on a wheel. The device includes an acceleration sensor provided on a wheel, and an output value of the acceleration sensor is predetermined. And a determination unit that detects an impact from the road surface to the wheel by determining whether or not the threshold is exceeded. A wheel-side communication device that transmits the output of the acceleration sensor and a vehicle body-side communication device that communicates with the wheel-side communication device may be further provided. The determination unit may also be provided on the wheel side, and a warning signal may be transmitted from the wheel side communication device to the vehicle body side communication device when the output value of the acceleration sensor exceeds a predetermined threshold value. Both the wheel side communication device and the vehicle body side communication device may be capable of bidirectional communication, or the wheel side communication device may have a transmission only function and the vehicle body side communication device may have a reception only function.

  According to this configuration, it is possible to directly detect the action of force on the wheel by the acceleration sensor provided on the wheel, and it is difficult to be affected by the disturbance, accurately detecting the impact force on the wheel, and warning the user. can do. In order to efficiently measure the magnitude of the impact force from the road surface to the wheel, the acceleration sensor may detect at least one of a circumferential acceleration and a radial acceleration of the wheel. The determination unit may determine the presence or absence of an impact based on both the circumferential acceleration and the radial acceleration.

  The determination unit may determine the impact strength to the wheel by comparing the output value of the acceleration sensor with a plurality of different threshold values. Moreover, you may further provide the warning part which issues a warning in steps according to the impact strength which a determination part determines. The warning unit can generate an alarm at an appropriate level by changing the degree of alarm and the alarm means according to the impact strength, thereby avoiding the user from being excessively alarmed and unnecessarily troublesome.

  Further, the warning unit may issue a warning indicating the degree of decrease in fatigue strength with reference to a table in which the impact force on the wheel is associated with the degree of decrease in the fatigue strength of the wheel. For example, the warning unit shall determine the life of the wheel from the magnitude of the impact acceleration based on the table showing the relationship between the output value of the acceleration sensor and the life of the wheel, and indicate the appropriate replacement time of the wheel at the time of alarm. Can do.

  When an impact is detected by the determination unit, a recording unit may be further provided that records the output value of the acceleration sensor as history information together with the detection time. The user can appropriately determine the necessity of wheel inspection and the vehicle inspection timing based on the recorded history information about the impact, and refer to the history information at the time of vehicle inspection. Can be easily grasped.

  According to the wheel state detection device of the present invention, it is possible to detect an excessive impact on the wheel, issue an alarm, and prompt an inspection.

  FIG. 1 shows an overall configuration of a vehicle 10 including a wheel state detection device according to an embodiment. The vehicle 10 includes four tires 20 a to 20 d and a vehicle body 12. The tires 20a to 20d include acceleration sensors 30a to 30d that detect accelerations of the tires 20a to 20d, transmitters 40a to 40d that transmit the detected acceleration information to the vehicle body 12, and transmission antennas 50a to 50d, respectively. And are provided. The vehicle body 12 includes a receiver 62 that receives acceleration information from each of the tires 20a to 20d, a receiving antenna 60, and an electronic control device that controls the vehicle 10 (hereinafter referred to as "ECU"). 64 and a warning buzzer 70 and a warning lamp 72 are provided. The ECU 64 has a function of detecting an impact on the tires 20a to 20d based on the acceleration information received from the receiver 62 and warning the user to prompt the inspection of the tires 20a to 20d. Hereinafter, when the configuration is described without distinguishing each wheel, the symbols a to d that distinguish each wheel are omitted.

  2A to 2C are cross-sectional views of the tire 20, and in these drawings, the mounting location of the acceleration sensor 30 is shown. The tire 20 and the wheel 22 form one wheel. In the example of FIG. 2A, the acceleration sensor 30 is provided in the valve 24 of the wheel 22. In the example of FIG. 2B, the acceleration sensor 30 is provided on the outer peripheral side of the rim 26 of the wheel 22. In the example of FIG. 2C, the acceleration sensor 30 is provided on the inner surface side of the tire tread 28. For example, the acceleration sensor 30 is a biaxial sensor that can detect acceleration components in the circumferential direction and the radial direction of the tire 20. The acceleration sensor 30 may be installed together with various sensors such as an air pressure sensor and a temperature sensor. The transmitter 40 is provided in the valve 24 of the wheel 22, is connected to the acceleration sensor 30, receives the detected values of acceleration in the circumferential direction and the radial direction of the tire 20 from the acceleration sensor 30, and transmits them to the receiver 62 of the vehicle body 12. To do.

  FIG. 3 is a diagram for explaining the circumferential and radial accelerations of the tire 20 detected at the time of impact. When the tire 20 rides on the object 200 while traveling on the road surface 202, the apparent radius of the tire 20 shrinks while the speed of the tire 20 remains constant, so the acceleration in the circumferential direction 32 of the tire 20 increases momentarily. Further, the acceleration due to the impact is also detected in the radial direction 34 of the tire 20. Even when the tire 20 gets on and off the object 200 on the road surface 202, an instantaneous impact acceleration similarly occurs. By detecting the occurrence of impact acceleration in at least one of the circumferential direction 32 and the radial direction 34 by the acceleration sensor 30, the ECU 64 can detect the impact force applied to the tire 20 by getting on or the like.

  FIG. 4 shows a configuration related to impact detection and warning of the ECU 64. The impact determination unit 102 receives the acceleration detection value G of each tire 20 via the receiver 62, checks whether the acceleration detection value G exceeds a predetermined impact acceleration reference value α, and determines the reference value α. When exceeding, it determines with the tire 20 having applied the excessive impact. The acceleration detection value G includes components in the circumferential direction and the radial direction of the tire 20, and the impact determination unit 102 determines each component for either or both of the circumferential direction and the radial direction of the acceleration detection value G. The occurrence of excessive impact is determined using a different reference value α for each.

  When the impact determination unit 102 determines that an excessive impact has occurred on the tire 20, the history information storage unit 104 detects the acceleration detection value G, the identification information of the tire 20 on which the impact has occurred, and the date and time of occurrence of the impact. Is recorded as history information. When the user requests a repair from a dealer or the like, the dealer accurately grasps the situation of the impact applied to the tire 20 based on the history information recorded in the history information storage unit 104, and malfunctions of the tire 20 and the wheel 22 occur. It is possible to take appropriate measures such as checking the situation and replacing the tire 20 and the wheel 22.

  When the impact determination unit 102 determines that an excessive impact has occurred, the warning unit 106 turns on the warning lamp 72 or sounds a warning sound to the buzzer 70 to apply an excessive impact to the tire 20. Let the driver know. The warning unit 106 may display a warning on a display unit of a navigation system (not shown). Note that the ECU 64 can also appropriately control other configurations of the vehicle 10 such as reducing the vehicle speed as a safety measure when an excessive impact is detected by the impact determination unit 102.

  The impact determination unit 102 evaluates the magnitude of the detected acceleration value G stepwise based on a plurality of different values of impact acceleration reference values, and distinguishes between the occurrence of a relatively mild impact and the occurrence of a severe impact. Alternatively, in the case of a slight impact, the history information storage unit 104 may only record the history information of the occurrence of the impact, and the warning unit 106 may not issue a warning.

  Further, the warning unit 106 refers to the life determination table 108, estimates the life years of the wheel 22 from the deformation amount of the rim 26 of the wheel 22 caused by excessive impact on the tire 20, and determines the replacement time of the wheel 22 to the driver. Can let you know. Generally, when the rim 26 of the wheel 22 is deformed by an impact, the fatigue strength of the wheel 22 is lowered and the life tends to be shortened. The life determination table 108 stores a table in which the deformation amount of the rim 26 is associated with the life years of the wheel 22.

  FIG. 5 is a flowchart showing a procedure of impact detection and warning by the ECU 64. The ECU 64 checks the speed v of the vehicle 10 and determines whether or not the vehicle 10 is traveling (S10). When the vehicle 10 is traveling (Y in S10), the process proceeds to a procedure for detecting the acceleration of the tire 20 after step S12. When the vehicle 10 is stopped (N in S10), the procedure for detecting the acceleration of the tire 20 is performed. Without returning to step S10.

  The impact determination unit 102 determines whether or not the detected value G of the acceleration of the tire 20 by the acceleration sensor 30 exceeds the reference value α (S12). FIG. 6 shows an example of a time change of the acceleration detection value G. FIG. At time t1, an impact is applied to the tire 20, and a steep change exceeding the reference value α appears in the acceleration detection value G. Even when the vehicle 10 is accelerated, the detected value G of the acceleration of the tire 20 increases, but in that case, the steep change as shown in FIG. That is, there is a significant difference between the change in the acceleration detection value G due to normal acceleration traveling of the vehicle 10 and the change in the acceleration detection value G due to an impact such as riding on the vehicle 10, and these can be distinguished. Note that the reference value α is not set as an absolute value of acceleration, but is set as a relative change amount from a steady acceleration value, and the impact determination unit 102 determines that the change amount of the detected acceleration value G is a reference change amount. It may be determined whether or not the value α is exceeded.

  If the acceleration detection value G does not exceed the reference value α in the determination by the impact determination unit 102 (N in S12), the process returns to step S10, and if the acceleration detection value G exceeds the reference value α (Y in S12), The history information storage unit 104 records the acceleration detection value G and the detection time together with the identification information of the tire 20 (S14).

  Next, the warning unit 106 warns the driver that an impact has been applied to the tire 20 (S16). The warning by the warning unit 106 is performed by the buzzer 70, the warning lamp 72, or the like, but when the driver performs a reset operation such as opening a door or pressing a predetermined button provided in a navigation system or the like (Y in S18). ), The warning unit 106 cancels the warning. When the driver does not perform the reset operation (N in S18), the warning unit 106 continuously issues an alarm such as lighting of the warning lamp 72. Even when the driver performs a reset operation such as opening the door, when the engine of the vehicle 10 is started, the warning unit 106 turns on the warning lamp 72 again, and the impact stored in the history information storage unit 104 during the inspection by the dealer. The alarm continues to be issued until the occurrence history information is cleared.

  A case will be described in which the impact determination unit 102 determines the strength of the impact based on a plurality of reference values of impact acceleration, and the warning unit 106 issues a warning step by step. FIG. 7 shows another example of the time change of the acceleration detection value G. As a reference value for impact acceleration, two values are provided: a first reference value α indicating a caution level and a second reference value β indicating an alarm level. Here, the second reference value β is set to a value larger than the first reference value α. At time t2, the detection value G has a steep change exceeding the first reference value α, but does not exceed the second reference value β. In this case, the impact determination unit 102 determines that the impact is mild. At time t3, the detection value G has a steep change exceeding the second reference value β. In this case, the impact determination unit 102 determines that the impact is severe.

  When the impact determination unit 102 determines that the impact is mild, the warning unit 106 only turns on the warning lamp 72 to alert the driver, and when it is determined that the impact is severe, the warning unit 72 changes the color of the warning lamp 72. Alarms are issued step by step according to the intensity of impact, such as changing or sounding the buzzer 70. The warning unit 106 does not issue an alarm every time the impact determination unit 102 detects a slight impact, but refers to the history information in the history information storage unit 104 to record a mild impact more than a predetermined number of times. An alarm may be issued for the first time. When a slight impact is accumulated, the fatigue strength of the tire 20 or the wheel 22 may be reduced. In this case, the warning unit 106 can issue an alarm to the driver to prompt an inspection.

  The present invention has been described based on the embodiments. The above embodiments are exemplifications, and it is understood by those skilled in the art that various modifications thereof are also included in the scope of the present invention. Examples of such modifications are given.

  In the above description, the tire side communicator has a transmission only function and the vehicle body side communicator only has a reception function. The tire-side communication device may transmit the output value of the acceleration sensor in response to a request issued from the communication device. Further, the communication device may be a transponder whose power is supplied by radio waves from the vehicle body side, or may be a communication device with a built-in battery. In the above description, only one communication device on the vehicle body side exists as the receiver 62. However, a total of four communication devices may be provided on the vehicle body side, one at a location near each tire.

  The acceleration sensor for detecting the impact acceleration may be one that detects acceleration in only one of the circumferential direction and the radial direction of the wheel, or may be one that detects acceleration in both directions. Further, a biaxial acceleration sensor may be provided to detect the acceleration in the circumferential direction and the radial direction, and separate acceleration sensors may be provided to detect the acceleration in each direction. Moreover, an acceleration sensor may be provided in either a tire or a wheel, and a separate acceleration sensor may be provided in both a tire and a wheel.

It is a figure showing the whole vehicle composition provided with the wheel state detecting device concerning an embodiment. It is a figure which shows the mounting location of the acceleration sensor of FIG. It is a figure explaining the acceleration of the circumferential direction of a tire detected at the time of an impact, and a radial direction. It is a figure which shows the structure regarding the impact detection and warning of ECU of FIG. It is a flowchart which shows the procedure of the impact detection and warning by ECU of FIG. It is a figure which shows the example of the time change of the detected value of the acceleration by the acceleration sensor of FIG. It is a figure which shows another example of the time change of the detected value of the acceleration by the acceleration sensor of FIG.

Explanation of symbols

20 tires, 30 acceleration sensors, 40 transmitters, 62 receivers, 64 ECUs, 70 buzzers, 72 warning lamps, 102 impact judgment units, 104 history information storage units, 106 warning units, 108 life judgment tables.

Claims (6)

In the wheel state detection device for detecting the wheel state based on the output value of the sensor provided on the wheel,
An acceleration sensor provided on the wheel;
A wheel state detection device comprising: a determination unit configured to detect an impact from the road surface to the wheel by determining whether an output value of the acceleration sensor exceeds a predetermined threshold value.   The wheel state detection device according to claim 1, wherein the acceleration sensor detects an acceleration in a circumferential direction of the wheel.   The wheel state detection device according to claim 1, wherein the acceleration sensor detects acceleration in a radial direction of the wheel.   4. The wheel state detection device according to claim 1, wherein the determination unit determines an impact strength to the wheel by comparing an output value of the acceleration sensor with a plurality of different threshold values. 5. .   The wheel state detection device according to claim 4, further comprising a warning unit that issues a warning in stages according to the impact strength determined by the determination unit. The wheel state detection device according to any one of claims 1 to 3, further comprising a recording unit that records an output value of the acceleration sensor as history information when an impact is detected by the determination unit.

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