Wheel condition determination device

Abstract

To make it easy to prevent interference between a signal transmitted by radio from a nut loosening detection device and a signal transmitted by radio from a tire pressure monitor device.SOLUTION: A state determination device comprises: a first sensor device which transmits by radio a first signal including information concerning a state of nuts fastening a wheel including a tire to a vehicle body; a second sensor device which transmits by radio a second signal including information concerning the inflation pressure of the tire; and a control unit which performs processing based upon the first signal received from the first sensor device and processing based upon the second signal received from the second sensor device. The first sensor device restricts the transmission of the first signal until a certain time passes from the start of rotation of the wheel as compared with after the certain time passes from the start of rotation of the wheel.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a wheel condition determination device. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2005-329907 (Patent Document 1) discloses a sensor device (hereinafter also referred to as a "nut loosening detection device") that wirelessly transmits the results of determining whether or not a nut that attaches a wheel to a vehicle body is loose, based on the detection value of a detector attached to the wheel of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-329907 Summary of the Invention [Problem to be solved by the invention]

[0004] In addition to the nut loosening detection device described above, vehicle wheels may be equipped with a tire pressure monitoring system (TPMS) that monitors the tire pressure of the wheels and transmits the monitoring results wirelessly. In this case, if the frequency band used for wireless transmission by the nut loosening detection device and the tire pressure monitoring device is the same, there is a risk of interference.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to make it easier to prevent interference between signals wirelessly transmitted from a nut loosening detection device and signals wirelessly transmitted from a tire pressure monitoring device during the period from when the wheel starts to rotate (when the vehicle starts to move) until a predetermined time has elapsed. [Means for solving the problem]

[0006] A state determination device according to one aspect of the present disclosure includes a first sensor device that wirelessly transmits a first signal including information regarding the state of a fastening member that fastens a wheel, including a tire, to a vehicle body, a second sensor device that wirelessly transmits a second signal including information regarding the tire air pressure, and a control device that performs processing based on the first signal received from the first sensor device and the second signal received from the second sensor device. The first sensor device limits transmission of the first signal until a predetermined time has elapsed since the wheel began to rotate, compared to after the predetermined time has elapsed since the wheel began to rotate.

[0007] According to the above aspect, transmission of the first signal from the first sensor device is restricted until a predetermined time has elapsed since the wheel starts to rotate. Therefore, even if the frequency band used for wireless communication of the first sensor device and the frequency band used for wireless communication of the second sensor device are the same, interference between the first signal from the first sensor device and the second signal from the second sensor device can be easily prevented during the period from when the wheel starts to rotate (when the vehicle starts to move) until the predetermined time has elapsed. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to easily prevent interference between a first signal from a first sensor device (nut loosening detection device) and a second signal from a second sensor device (tire pressure monitoring device) during the period from when the vehicle wheels start to rotate until a predetermined time has elapsed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram schematically illustrating a vehicle on which a state determination device is mounted; [Figure 2] 3 is a diagram showing an example of the configuration of a first sensor device (nut loosening detection device). FIG. [Figure 3] FIG. 4 is a diagram showing an example of the configuration of a second sensor device (tire pressure monitoring device). [Figure 4] 10 is a flowchart illustrating an example of a processing procedure executed by a signal processing unit of a first sensor device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0011] 1 is a diagram schematically showing a vehicle 200 equipped with a state determination device according to this embodiment. The vehicle 200 includes a communication terminal 201, a start switch 202, a control device 205, and a plurality of wheels 210.

[0012] Each of the plurality of wheels 210 includes a wheel 220 and a tire 230 attached to the wheel 220 .

[0013] The wheel 220 of each wheel 210 is attached to the body (more specifically, the wheel hub) of the vehicle 200 by five nuts 240. Note that the number of nuts 240 on each wheel 210 is not limited to five.

[0014] The first sensor device 100 is disposed on one of the five nuts 240 that attach each wheel 210 to the vehicle body. Note that the first sensor device 100 may be disposed on two or more of the five nuts 240 that attach each wheel 210 to the vehicle body.

[0015] The first sensor device 100 is attached (adhered) to, for example, the inner surface of a cap that is attached to the nut 240. The first sensor device 100 is configured to determine whether the nut 240 is loose and to wirelessly transmit the determination result. The first sensor device 100 is an example of a nut loosening detection device.

[0016] Fig. 2 is a diagram showing an example of the configuration of the first sensor device 100 (nut loosening detection device). Fig. 2 shows an example of the configuration when the first sensor device 100 determines whether the nut 240 is loose using an acceleration sensor. Note that the sensor used by the first sensor device 100 to determine whether the nut 240 is loose is not necessarily limited to an acceleration sensor, and may be, for example, a magnetic sensor.

[0017] The first sensor device 100 includes an acceleration sensor 1, a signal processing unit 2, a communication unit 3, and a power supply unit 4. The acceleration sensor 1 detects, for example, accelerations of two mutually orthogonal axes (X-axis and Y-axis) in a plane orthogonal to the rotation axis of the wheel 220.

[0018] The communication unit 3 is configured to be able to wirelessly communicate with a communication terminal 201 (see FIG. 1) of the vehicle 200. The communication unit 3 wirelessly transmits a signal indicating the processing result of the signal processing unit 2 to the communication terminal 201 (see FIG. 1) of the vehicle 200.

[0019] The power supply unit 4 supplies power to each of the acceleration sensor 1, the signal processing unit 2, and the communication unit 3. The power supply unit 4 can be realized by, for example, a button battery.

[0020] The signal processing unit 2 includes a processor such as a CPU (not shown), a memory, and an input / output buffer.

[0021] The signal processing unit 2 periodically wirelessly transmits a signal (hereinafter also referred to as a "first signal") including information regarding the state of the nut 240 from the communication unit 3 to the communication terminal 201 of the vehicle 200. Types of the first signal that the first sensor device 100 can wirelessly transmit include a function signal, a normal signal, and an abnormality signal.

[0022] The function signal is a signal transmitted by the first sensor device 100 for the purpose of notifying the control device 205 of the vehicle 200 that the first sensor device 100 has not fallen off the wheel 210 and is functioning normally. The signal processing unit 2 periodically transmits the function signal wirelessly from the communication unit 3 to the communication terminal 201 of the vehicle 200.

[0023] The normal signal is a signal indicating that it has been detected that the nut 240 is not loose. The abnormal signal is a signal indicating that it has been detected that the nut 240 is loose. The signal processing unit 2 periodically executes a determination process to determine whether the nut 240 is loose or not based on the signals (acceleration in the X-axis direction and acceleration in the Y-axis direction) from the acceleration sensor 1. If the determination process detects that the nut 240 is not loose, the signal processing unit 2 wirelessly transmits a normal signal from the communication unit 3 to the communication terminal 201 of the vehicle 200. On the other hand, if the determination process detects that the nut 240 is loose, the signal processing unit 2 wirelessly transmits an abnormal signal from the communication unit 3 to the communication terminal 201 of the vehicle 200.

[0024] Returning to FIG. 1 , in addition to the first sensor device 100, a second sensor device 150 is disposed on the wheel 220 of each wheel 210. The second sensor device 150 is formed integrally with a valve for drawing air into the tire 230, for example. The second sensor device 150 is configured to monitor the air pressure of the tire 230 of the wheel 210 and wirelessly transmit the monitoring results. The second sensor device 150 is an example of a tire pressure monitoring device.

[0025] 3 is a diagram showing an example of the configuration of the second sensor device 150 (tire pressure monitoring device). The second sensor device 150 includes a pressure sensor 5, a signal processing unit 6, a communication unit 7, and a power supply unit 8. The pressure sensor 5 detects the air pressure of a tire 230.

[0026] The communication unit 7 is configured to be able to wirelessly communicate with a communication terminal 201 (see FIG. 1) of the vehicle 200. The communication unit 7 periodically wirelessly transmits a signal indicating the processing result of the signal processing unit 6 to the communication terminal 201 (see FIG. 1) of the vehicle 200.

[0027] The power supply unit 8 supplies power to each of the pressure sensor 5, the signal processing unit 6, and the communication unit 7. The power supply unit 8 can be realized by, for example, a button battery.

[0028] The signal processing unit 6 includes a processor such as a CPU (not shown), a memory, and an input / output buffer.

[0029] The signal processing unit 6 wirelessly transmits a signal including information regarding the air pressure of the tire 230 (hereinafter also referred to as the "second signal") from the communication unit 7 to the communication terminal 201 of the vehicle 200. The signal processing unit 6 monitors whether the air pressure of the tire 230 has dropped below a reference value (whether the tire 230 is punctured) based on the signal from the pressure sensor 5, and wirelessly transmits the monitoring result as the second signal.

[0030] The first sensor device 100 and the second sensor device 150 described above operate independently (stand-alone).

[0031] Returning to FIG. 1, the communication terminal 201 is configured to be able to wirelessly communicate with the first sensor device 100 and the second sensor device 150 of each wheel 210.

[0032] Start switch 202 is a button that is pressed by the user when the user wants to start the control system of vehicle 200 and run vehicle 200. When the user presses start switch 202 while the control system of vehicle 200 is stopped, the control system of vehicle 200 including control device 205 is started, and vehicle 200 becomes ready to run.

[0033] The control device 205 includes a processor such as a CPU (Central Processing Unit) (not shown), a memory, and an input / output buffer.

[0034] The control device 205 determines whether there is a sign of the wheel 210 falling off based on the first signal received from the first sensor device 100 (nut loosening detection device) of each wheel 210. If it is determined that there is a sign of the wheel 210 falling off, it executes a process of notifying the user of this (for example, a process of displaying on a display (not shown) that there is a sign of the wheel 210 falling off).

[0035] Furthermore, the control device 205 monitors whether or not the tire 230 has a reduced pressure (puncture) based on a second signal received from the second sensor device 150 (tire pressure monitoring device) of the wheel 210. If it is determined that the tire 230 has a reduced pressure (puncture), the control device 205 executes a process of notifying the user of this (for example, a process of displaying on a display (not shown) that the tire 230 has a reduced pressure (puncture)).

[0036] <Preventing interference between the first and second signals> In the vehicle 200 having the above-described configuration, if the frequency band used for wireless communication of the first sensor device 100 (nut loosening detection device) and the frequency band used for wireless communication of the second sensor device 150 (tire pressure monitoring device) are the same, there is a risk of interference. If interference occurs, there is a concern that the control device 205 of the vehicle 200 may not be able to accurately receive the first signal from the first sensor device 100 and the second signal from the second sensor device 150.

[0037] In particular, in tire pressure monitoring systems (TPMS), regulations may require that tire pressure monitoring systems notify the user of tire deflation within a certain period of time (e.g., several minutes) after the vehicle 200's control system is started or the vehicle starts to travel. Some tire pressure monitoring systems also have an auto-location function that automatically determines the location of the tire on which the tire pressure monitoring device is installed after the vehicle's control system is started or the vehicle starts to travel. When the auto-location function is included, the system must determine the tire location on which the tire pressure monitoring device is installed using the auto-location function within a certain period of time after the vehicle's control system is started or the vehicle starts to travel, and then notify the user of tire deflation. Nevertheless, if a nut loosening detection device also transmits radio waves in the same frequency band as the radio waves of the tire pressure monitoring device while the tire pressure monitoring device is transmitting radio waves, interference between the two radio waves may occur, potentially preventing the installation location of the tire pressure monitoring device from being determined and the user from being notified of tire deflation within a certain period of time after the vehicle starts to travel.

[0038] Therefore, the first sensor device 100 (nut loosening detection device) according to this embodiment restricts communication of the first signal for a certain period of time (e.g., several minutes) after the vehicle 200 starts traveling, in order to prioritize wireless communication with the second sensor device 150 (tire pressure monitoring device). Specifically, the first sensor device 100 limits the content of the first signal to the minimum. For example, among the types of first signals, the above-mentioned functional signal and normal signal are not transmitted because they are of low urgency. On the other hand, an abnormal signal indicating a loose nut 240 is transmitted in bursts even within a certain period of time after the vehicle starts traveling because it is of high urgency. In other words, the first sensor device 100 limits the type of first signal that can be transmitted within a certain period of time after the vehicle starts traveling to only the abnormal signal.

[0039] 4 is a flowchart showing an example of a processing procedure executed by the signal processing unit 2 of the first sensor device 100. This flowchart is repeatedly executed every time a predetermined condition is met.

[0040] The signal processing unit 2 determines whether the time during which the tire 230 has been stopped is longer than a threshold time (step S10). This determination is a process for estimating whether the vehicle 200 is temporarily stopped while the control system of the vehicle 200 is operating, such as waiting at a traffic light, or whether the user has already gotten off the vehicle and the control system of the vehicle 200 is stopped. Therefore, the threshold time is set to a relatively long time (for example, about several hours).

[0041] The first sensor device 100 cannot grasp the state of the control system of the vehicle 200 unless it acquires information from the control device 205 of the vehicle 200. Therefore, the signal processing unit 2 of the first sensor device 100 grasps the state of the tire 230 based on the output of the acceleration sensor 1, and estimates the state of the control system of the vehicle 200 based on the result. Specifically, in view of the fact that the output of the acceleration sensor 1 does not change while the tire 230 is stopped, the signal processing unit 2 estimates that the control system of the vehicle 200 is stopped when the time during which the output of the acceleration sensor 1 does not change (= the time during which the tire 230 continues to be stopped) is longer than a threshold time.

[0042] If the time that tire 230 continues to be stopped is shorter than the threshold time (NO in step S10), signal processing unit 2 does not impose a wireless communication restriction on the first signal (step S50). Specifically, signal processing unit 2 allows the transmission of an abnormal signal, which is of high urgency, while not wirelessly transmitting a functional signal or a normal signal, which is of low urgency. As a result, when vehicle 200 is temporarily stopped, such as waiting at a traffic light, wireless communication restriction on the first signal can be avoided even if vehicle 200 starts moving after that.

[0043] If the time that tire 230 has been stopped is longer than the threshold time (YES in step S10), it is estimated that the control system of vehicle 200 is stopped, and therefore signal processing unit 2 determines whether tire 230 has started to rotate (step S20). This determination is a process for determining whether the user has activated the control system of vehicle 200 and started running vehicle 200. For example, when the output of acceleration sensor 1 changes, signal processing unit 2 determines that tire 230 has started to rotate, that is, that vehicle 200 has started to run.

[0044] If tire 230 remains stationary (NO in step S20), it is estimated that the control system of vehicle 200 is still stationary, and therefore signal processing unit 2 does not impose any wireless communication restriction on the first signal (step S50). Specifically, signal processing unit 2 allows wireless transmission not only of abnormal signals with high urgency, but also of functional signals and normal signals with low urgency.

[0045] If tire 230 starts to rotate (YES in step S20), it is estimated that the user has activated the control system of vehicle 200 and started running vehicle 200, and therefore signal processing unit 2 restricts wireless communication of the first signal (step S30). Specifically, signal processing unit 2 allows the transmission of an abnormal signal, which is of high urgency, but does not wirelessly transmit functional signals and normal signals, which are of low urgency.

[0046] Next, the signal processing unit 2 determines whether a certain time (for example, several minutes) has passed since the tire 230 began to rotate (step S40). If the certain time has not passed since the tire 230 began to rotate (NO in step S40), the signal processing unit 2 returns the process to step S30 and continues to restrict wireless communication of the first signal. This restricts wireless communication of the first signal during the period from when the user activates the control system of the vehicle 200 and starts driving the vehicle 200 until the certain time has passed, making it easier to prevent interference between the first signal and the second signal. As a result, wireless communication of the second sensor device 150 (tire pressure monitoring device) can be given priority.

[0047] On the other hand, if a certain time has passed since the tire 230 started to rotate (YES in step S40), it is estimated that wireless communication of the second sensor device 150 has already been performed within the certain period after the vehicle 200 started to travel, and therefore the signal processing unit 2 removes the wireless communication restriction on the first signal (step S50). That is, the signal processing unit 2 allows wireless transmission not only of abnormal signals with high urgency, but also of functional signals and normal signals with low urgency.

[0048] As described above, the first sensor device 100 (nut loosening detection device) according to this embodiment restricts communication of the first signal for a certain period of time after the vehicle 200 starts traveling. Specifically, the first sensor device 100 allows transmission of abnormal signals, which are of high urgency, among the types of first signals, while not wirelessly transmitting functional signals and normal signals, which are of low urgency. As a result, even if the frequency band used for wireless communication of the first sensor device 100 (nut loosening detection device) and the frequency band used for wireless communication of the second sensor device 150 (tire pressure monitoring device) are the same, interference between the first signal from the first sensor device 100 and the second signal from the second sensor device 150 can be easily prevented for a certain period of time after the vehicle 200 starts traveling.

[0049] In the above-described embodiment, as an example of restricting communication of the first signal within a certain period of time after the vehicle starts traveling, an example has been described in which the type of transmission of the first signal is restricted, i.e., only transmission of a high-urgency abnormal signal is permitted, and wireless transmission of a low-urgency functional signal and a normal signal is not permitted. However, the method of restricting communication of the first signal is not limited to this. For example, as a method of restricting communication of the first signal, instead of or in addition to restricting the type of transmission of the first signal, the frequency of transmission of the first signal may be restricted. For example, for a certain period of time after the vehicle starts traveling, the frequency of transmission of a low-urgency functional signal and a normal signal may be significantly reduced compared to after a certain period of time has elapsed after the vehicle starts traveling. This also makes it easier to prevent interference between the first signal from the first sensor device 100 and the second signal from the second sensor device 150 within a certain period of time after the vehicle starts traveling.

[0050] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0051] The exemplary embodiment and its modifications described above are specific examples of the following aspects.

[0052] (Item 1) A wheel condition determination device according to the present disclosure includes a first sensor device that wirelessly transmits a first signal including information regarding the condition of a fastening member that fastens a wheel, including a tire, to a vehicle body, a second sensor device that wirelessly transmits a second signal including information regarding tire air pressure, and a control device that performs processing based on the first signal received from the first sensor device and the second signal received from the second sensor device. The first sensor device limits transmission of the first signal until a predetermined time has elapsed since the wheel began to rotate, compared to after the predetermined time has elapsed since the wheel began to rotate.

[0053] According to the above aspect, transmission of the first signal from the first sensor device is restricted until a predetermined time has elapsed since the wheel starts to rotate. Therefore, even if the frequency band used for wireless communication of the first sensor device and the frequency band used for wireless communication of the second sensor device are the same, interference between the first signal from the first sensor device and the second signal from the second sensor device can be easily prevented during the period from when the wheel starts to rotate (when the vehicle starts to move) until the predetermined time has elapsed.

[0054] (Item 2) In the state determination device described in item 1, the types of first signals that the first sensor device can wirelessly transmit include a function signal indicating that the first sensor device is functioning normally, a normal signal indicating that a fastening member is not loose, and an abnormality signal indicating that a fastening member is loose. The first sensor device allows transmission of the abnormality signal while restricting transmission of the function signal and the normal signal until a predetermined time has elapsed since the wheel started to rotate, and allows transmission of the function signal, the normal signal, and the abnormality signal after the predetermined time has elapsed since the wheel started to rotate.

[0055] According to the above aspect, during a predetermined time period after the wheels start rotating, of the three types of first signals (function signal, normal signal, and abnormal signal), transmission of the less urgent function signal and normal signal is restricted, but transmission of the more urgent abnormal signal is permitted. Therefore, during a predetermined time period after the wheels start rotating (after the vehicle starts moving), it is possible to notify the control device that a fastening member has loosened while easily preventing interference between the first signal and the second signal.

[0056] (Item 3) In the state determination device described in Items 1 or 2, the first sensor device includes an acceleration sensor that detects acceleration applied to the fastening member, a control unit, and a wireless transmission unit. The control unit determines whether the wheel has started to rotate based on the output of the acceleration sensor, and limits transmission of the first signal until a predetermined time has elapsed since it was determined that the wheel has started to rotate.

[0057] According to the above aspect, the first sensor device can detect that the wheels have started to rotate (that the vehicle has started to move) based on the output of the acceleration sensor and restrict the transmission of the first signal, without obtaining information from another device.

[0058] (4) In the state determination device described in paragraph 3, the control unit determines whether the tire has been stopped for a predetermined period of time based on the output of the acceleration sensor, and after it is determined that the tire has been stopped for the predetermined period of time, it determines whether the wheel has started to rotate, and restricts the transmission of the first signal until a predetermined time has elapsed from the time it is determined that the wheel has started to rotate.

[0059] According to the above aspect, in a situation where the wheels of the vehicle start to rotate after the vehicle has temporarily stopped, such as waiting at a traffic light, transmission of the first signal can be prevented from being restricted. [Explanation of symbols]

[0060] 1 acceleration sensor, 2, 6 signal processing unit, 3, 7 communication unit, 4, 8 power supply unit, 5 pressure sensor, 100 first sensor device, 150 second sensor device, 200 vehicle, 201 communication terminal, 202 start switch, 205 control device, 210 wheel, 220 wheel, 230 tire, 240 nut.

Claims

1. a first sensor device that wirelessly transmits a first signal including information regarding the state of a fastening member that fastens a wheel including a tire to a vehicle body; a second sensor device configured to wirelessly transmit a second signal including information regarding the tire pressure; a control device that performs processing based on the first signal received from the first sensor device and processing based on the second signal received from the second sensor device, A wheel state determination device, wherein the first sensor device limits transmission of the first signal until a predetermined time has elapsed since the wheel started to rotate, compared to after the predetermined time has elapsed since the wheel started to rotate.

2. types of the first signal that the first sensor device can wirelessly transmit include a function signal indicating that the first sensor device is functioning normally, a normal signal indicating that the fastening member is not loosened, and an abnormal signal indicating that the fastening member is loosened; The first sensor device restricting transmission of the function signal and the normal signal while allowing transmission of the abnormal signal until a predetermined time has elapsed since the wheel started to rotate; 2. The wheel condition determination device according to claim 1, wherein transmission of the function signal, the normal signal, and the abnormal signal is permitted after the predetermined time has elapsed since the wheel started to rotate.

3. The first sensor device an acceleration sensor that detects acceleration applied to the fastening member; A control unit; a wireless transmitter; The control unit determining whether the wheel has started to rotate based on the output of the acceleration sensor; 3. The wheel condition determination device according to claim 1, wherein transmission of the first signal is restricted until the predetermined time has elapsed from the time when it is determined that the wheel has started to rotate.

4. The control unit determining whether the tire has been stopped for a predetermined period of time based on the output of the acceleration sensor; After it is determined that the stop period of the tire has continued for a predetermined period, it is determined whether the wheel has started to rotate; 4. The wheel condition determination device according to claim 3, wherein transmission of the first signal is restricted until the predetermined time has elapsed from the time when it is determined that the wheel has started to rotate.

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