WO2023026454A1

WO2023026454A1 - Bracket and looseness determination device

Info

Publication number: WO2023026454A1
Application number: PCT/JP2021/031439
Authority: WO
Inventors: 博久山田
Original assignee: 太平洋工業株式会社
Priority date: 2021-08-27
Filing date: 2021-08-27
Publication date: 2023-03-02

Abstract

A wheel (14) is fixed to an axle (11) by the threaded engagement between male and female threads at each of a plurality of fastening points around an axis (m1) of the axle (11). A wheel nut (20) or bolt (80) that generates an axial force to fix the wheel (14) to the axle (11) serves as a fixing member. A bracket (40) that is configured to be provided on the wheel (14) comprises a body (50) having a base (51) that is located on an extension of the axle (11) and an arm (52) that extends radially from the base (51) toward each of the fixing members located at the plurality of fastening points. The bracket (40) is equipped with sensors (61, 66) that detect changes in the behavior of the body (50).

Description

Bracket and looseness detection device

The present disclosure relates to brackets and looseness determination devices.

A vehicle includes a plurality of axles, a plurality of hubs, a plurality of wheels, and a fixing member that generates an axial force for fixing the wheels to the axles. One hub is provided at each end of the axle. The wheel is rotatable integrally with the axle by fastening a fixing member to the hub.

　In order to prevent the wheel from falling off the axle, there is a known technology that detects the fastening state of the fixing member. For example, Patent Literature 1 discloses a sensor unit that detects an abnormality in the fastening state of a wheel nut as a fixing member. The sensor unit includes a ring-shaped spacer member and a strain sensor as a sensor attached to the spacer member. A spacer-like member is interposed, for example, between the wheel and the hub. The spacer-like member is compressed and deformed between the wheel and the hub by screwing together the plurality of hub bolts and the plurality of wheel nuts. When the wheel nut is loosened, the strain sensor detects a change in behavior of the spacer-like member as a change in strain, thereby detecting an abnormality in the fastening state of the wheel nut.

Japanese Patent No. 6545528

However, if one of all the fixing members is loosened or if the fixing member is about to be loosened, the behavior of the spacer-like member is difficult to change. Therefore, if there is no looseness in the plurality of fixing members, there is a possibility that the looseness of the fixing members cannot be detected by the sensor.

According to a first aspect of the present disclosure, a bracket configured to be mounted on a wheel, wherein the wheel is mounted on the axle by threaded engagement of male and female threads at each of a plurality of fastening points about the axis of the axle. A fixing member is a member that is fixed to and has the male thread or the female thread and generates an axial force for fixing the wheel to the axle, and the bracket is a main body and extends on the extension of the axle and an arm portion radially extending from the base portion toward each of the fixing members positioned at the plurality of fastening points and positioned with respect to the fixing member while being in contact with the fixing member. and a sensor configured to detect a change in behavior of the body.

According to this, even if one of all the fixing members is loosened, the behavior of the arm positioned with respect to the fixing member changes. A change in behavior of the arm causes a change in behavior of the main body. Therefore, the sensor can detect loosening of the fixing member by detecting a change in behavior of the main body. Therefore, it is possible to detect the loosening of the fixing members even if the plurality of fixing members are not loosened.

With regard to the above bracket, the sensor is an acceleration sensor, and the acceleration sensor is preferably provided at a position where the distances from all the fixing members are the same.

In the above bracket, the sensor may be a strain sensor provided on at least one of the arms, and the strain sensor may be attached to at least one of the base and the arm. .

The bracket may include a transmitter configured to transmit the detection signal of the sensor.

According to a second aspect of the present disclosure, there is provided a looseness determination device for determining looseness of a fixing member that generates an axial force for fixing a wheel to an axle, wherein the wheel has a plurality of fastening points around the axis of the axle. is fixed to the axle by screwing a male screw and a female screw in each of the brackets, the fixing member has the male screw or the female screw, and the looseness determination device is a bracket configured to be provided on the wheel, , a base positioned on the extension of the axle, and radially extending from the base towards each of the fixing members positioned at the plurality of fastening locations, and positioned with respect to the fixing member while being in contact with the fixing member. a bracket comprising: a main body having an arm that is shaped like an arm; a sensor configured to detect a change in behavior of the main body; and a transmitter; and receiving a signal transmitted from the transmitter. and a determination unit configured to determine looseness of the fixing member based on the detection signal of the sensor.

With regard to the looseness determination device, it is preferable that the sensor is an acceleration sensor, and the acceleration sensor is provided at a position where the distances from all the fixing members are the same.

With regard to the looseness determination device, the determination unit may be provided in the receiver and configured to determine looseness of the fixing member based on the detection signal of the acceleration sensor transmitted from the transmitter.

In the above looseness determination device, the sensor is a strain sensor provided on at least one of the arms, the strain sensor is attached to at least one of the base and the arm, and The determination unit may be provided in the receiver and configured to determine looseness of the fixing member based on a detection signal of the strain sensor transmitted from the transmitter.

1 is a schematic configuration diagram of a vehicle; FIG. 2 is an exploded perspective view of a hub included in the vehicle in FIG. 1, a wheel included in the vehicle in FIG. 1, a wheel nut included in the vehicle in FIG. 1, and a bracket included in the vehicle in FIG. 1. FIG. It is sectional drawing when cut|disconnecting 1st Embodiment of a bracket. 2 is a schematic configuration diagram of a transmitter and a receiver provided in the vehicle of FIG. 1; FIG. 2 is a graph showing amplitudes of acceleration values used in wheel nut looseness determination executed by a receiver provided in the vehicle of FIG. 1; The perspective view which shows 2nd Embodiment of a bracket. It is sectional drawing when cutting 2nd Embodiment of a bracket. FIG. 2 is a graph showing changes in values of a strain sensor used in wheel nut looseness determination performed by a receiver provided in the vehicle of FIG. 1 ; FIG. FIG. 11 is a schematic diagram showing a modified example of the arms of the bracket; FIG. 5 is a cross-sectional view showing a modification of the means for fixing the main body of the bracket to the wheel;

[First embodiment]
A looseness determination device and a bracket according to a first embodiment will be described. For convenience of explanation, the structure of the vehicle will be described before the structure of the looseness determination device and the structure of the bracket.

<Vehicle configuration>
As shown in FIG. 1 , the vehicle 10 includes multiple axles 11 , multiple hubs 12 , multiple wheels 14 , multiple wheel nuts 20 , and a looseness determination device 30 . Vehicle 10 may be of any type, such as a truck, bus, passenger car, commercial vehicle, or the like.

As shown in FIG. 2, one hub 12 is provided at each end of the axle 11 . The hub 12 can rotate integrally with the axle 11 . Hub 12 has a plurality of hub bolts 13 . In this embodiment, six hub bolts 13 are employed for one hub 12 . All the hub bolts 13 are arranged at a plurality of locations around the axis m1 of the axle 11 at intervals. Around the axis m1 of the axle 11 is the direction of rotation of the axle 11 . All the hub bolts 13 are arranged around the axis m1 of the axle 11 at regular intervals. All the hub bolts 13 pass through the wheel 14 at a plurality of points around the axis m1 of the axle 11. - 特許庁It should be noted that the number of hub bolts 13 may be appropriately changed as long as two or more hub bolts 13 are provided for one hub 12 .

As shown in FIG. 3, the wheel nut 20 is a hexagonal cap nut. The wheel nut 20 is located on the opposite side of the wheel 14 from the axle 11 in the axial direction of the axle 11 . The wheel nut 20 has a fastening portion 21 to which the hub bolt 13 is fastened. The fastening portion 21 has an inner peripheral surface 22 defining a screw hole 23 . The hub bolt 13 is inserted into the threaded hole 23 . The threaded hole 23 has a female thread into which the male thread of the hub bolt 13 is screwed. The wheel nut 20 is an example of a fixing member that generates an axial force for fixing the wheel 14 to the axle 11 . The wheel nut 20 is a member that strengthens or weakens the axial force for fixing the wheel 14 to the axle 11 by relatively moving in the axial direction of the axle 11 . The wheel nut 20 has a first surface 24 and a second surface 25 located on the side opposite to the first surface 24 in the axial direction of the fastening portion 21 .

As shown in FIG. 2, wheel nuts 20 are fastened to the hub bolts 13 passing through the wheel 14 at a plurality of locations around the axis m1 of the axle 11 . The wheel 14 is fixed to the axle 11 by screwing the male thread of the hub bolt 13 and the female thread of the wheel nut 20 at each of a plurality of fastening points around the axis m1 of the axle 11 . Wheel 14 is fixed to axle 11 via hub 12 . Although the case where one wheel 14 is provided on each end of each axle 11 has been described, the present invention is not limited to this. For example, a plurality of wheels 14 may be provided on each of both ends of at least one axle 11 among the plurality of axles 11 . That is, each end of the axle 11 may be provided with one wheel for a single tire or two wheels for a double tire.

<Structure of looseness determination device and structure of bracket>
As shown in FIG. 1 , the slackness determination device 30 includes a bracket 40 and a receiver 70 . Bracket 40 is configured to be mounted on wheel 14 . In this embodiment, brackets 40 are provided on all four wheels 14 of vehicle 10 . Receiver 70 is mounted inside vehicle 10 . The bracket 40 has a body portion 50 and a weight 60 .

<About the main unit>
As shown in FIG. 2, the body portion 50 is a plate-like member. The body portion 50 is located on the opposite side of the wheel 14 from the axle 11 in the axial direction of the axle 11 . The body portion 50 has a disk-shaped base portion 51 and a plurality of arm portions 52 extending from the base portion 51 . The base 51 is located on the extension of the axle 11 . The base portion 51 includes a first surface 51a and a second surface 51b located on the side opposite to the first surface 51a in the thickness direction of the base portion 51 .

Each of all the arms 52 has a plate shape. All arms 52 extend radially from base 51 . In this embodiment, six arm portions 52 are employed for one base portion 51 . All the arms 52 are arranged around the axis m1 of the axle 11 at regular intervals. Note that the number of arms 52 may be changed as appropriate as long as it is the same as the number of hub bolts 13 .

Next, the configuration of the arm portion 52 will be described with reference to FIG. For convenience of explanation, only two arms 52 are shown in FIG. 3, and illustration of the remaining arms 52 is omitted from FIG.

As shown in FIG. 3 , the arm portion 52 has a plate-like first portion 521 and a plate-like second portion 522 . The first portion 521 has a first surface 521a and a second surface 521b positioned opposite to the first surface 521a in the thickness direction of the first portion 521 . The first surface 521a of the first portion 521 and the first surface 51a of the base portion 51 are continuous. The second surface 521b of the first portion 521 and the second surface 51b of the base portion 51 are continuous. The first portion 521 is inclined with respect to the base portion 51 . A first surface 521 a of the first portion 521 is inclined with respect to the first surface 51 a of the base portion 51 . A second surface 521 b of the first portion 521 is inclined with respect to the second surface 51 b of the base portion 51 . The inclination angles of all the first portions 521 with respect to the base portion 51 are the same.

The second portion 522 extends from a portion of the first portion 521 located on the opposite side of the base portion 51 . The second portion 522 has a first surface 522b and a second surface 522c positioned opposite to the first surface 522b in the thickness direction of the second portion 522 . The first surface 522b of the second portion 522 and the first surface 521a of the first portion 521 are continuous. The second surface 522c of the second portion 522 and the second surface 521b of the first portion 521 are continuous. The first surface 522b of the second portion 522 and the first surface 51a of the base portion 51 are parallel. The second portion 522 has an insertion hole 522a. The insertion hole 522a is a hole through which the hub bolt 13 passing through the wheel 14 is inserted. The second portion 522 has the second surface 522c in contact with the wheel 14 while the hub bolt 13 is inserted through the insertion hole 522a.

A wheel nut 20 is fastened to the hub bolt 13 that has passed through the insertion hole 522a of the second portion 522. When the wheel nut 20 is brought closer toward the wheel 14 , the second surface 25 of the wheel nut 20 contacts the first surface 522 b of the second portion 522 . As the wheel nut 20 is brought closer to the wheel 14 , the wheel nut 20 presses the second portion 522 against the wheel 14 . The force with which the wheel nut 20 presses the second portion 522 toward the wheel 14 serves as an axial force for fixing the wheel 14 to the axle 11 . All the arm portions 52 radially extend from the base portion 51 toward each of the wheel nuts 20 located at a plurality of fastening points. All arms 52 are fastened together to wheel 14 by wheel nuts 20 . The arm portion 52 does not move relative to the wheel nut 20 when the arm portion 52 is sandwiched between the wheel nut 20 and the wheel 14 . Therefore, all the arm portions 52 are positioned with respect to the wheel nut 20 while contacting the wheel nut 20 . In addition, the main-body part 50 is metal.

<Structure of weight>
As shown in FIG. 3, weight 60 has acceleration sensor 61 and transmitter 62 . The weight 60 is a member in which the acceleration sensor 61 and the transmitter 62 are integrated with resin or the like. The acceleration sensor 61 and transmitter 62 are electrically connected. Various configurations are conceivable as means for integrating the acceleration sensor 61 and the transmitter 62 in the weight 60 . For this reason, FIG. 3 does not show the detailed configuration of the weight 60, but shows the general configuration with a chain double-dashed line.

The weight 60 is provided on the opposite side of the base 51 to the wheel 14 in the axial direction of the axle 11 . Weight 60 is provided on axis m1 of axle 11 . An acceleration sensor 61 is also provided on the axis m1 of the axle 11 . The acceleration sensor 61 is provided at a position where the distances D1 from the six wheel nuts 20 that fix one wheel 14 to the axle 11 are the same. The distance D1 is the distance between the axis m2 of the wheel nut 20 and the axis m1 of the axle 11 .

<Configuration of transmitter and configuration of receiver>
As shown in FIG. 4 , the transmitter 62 has a transmitter control device 63 , a transmission circuit 64 and a transmission antenna 65 .

The transmitter control device 63 has a processor 63a and a storage section 63b. Examples of the processor 63a include an MPU (Micro Processing Unit), a CPU (Central Processing Unit), and a DSP (Digital Signal Processor).

The storage unit 63b includes RAM (Random Access Memory) and ROM (Read Only Memory). The storage unit 63b stores program codes or instructions configured to cause the processor 63a to perform processing.

The transmitter control device 63 may be composed of hardware circuits such as ASIC and FPGA. The processing circuitry, transmitter controller 63, may include one or more processors operating according to a computer program, one or more hardware circuits such as ASICs or FPGAs, or a combination thereof. ROM and RAM or computer-readable media include any available media that can be accessed by a general purpose or special purpose computer.

The transmitter control device 63 inputs the detection signal detected by the acceleration sensor 61 to the transmission circuit 64 . The transmission circuit 64 transmits a radio signal modulated according to the detection signal of the acceleration sensor 61 input from the transmitter control device 63 from the transmission antenna 65 . That is, the transmitter 62 is configured to transmit the detection signal of the acceleration sensor 61 . The transmitter 62 transmits the detection signal of the acceleration sensor 61 to the receiver 70 . A radio signal is a signal in a predetermined frequency band. Examples of frequency bands include the LF band, MF band, HF band, VHF band, UHF band, and 2.4 GHz band. The transmitter control device 63 is configured to cause the transmission circuit 64 to transmit radio signals at predetermined transmission intervals. The predetermined transmission interval may be a predetermined constant interval, or may be an interval that randomly fluctuates between a predetermined upper limit and lower limit.

The receiver 70 is configured to receive the signal transmitted from the transmitter 62 . The receiver 70 has a receiver control device 71 , a receiving antenna 72 and a receiving circuit 73 .

The receiver control device 71 has a processor 71a and a storage section 71b. Examples of the processor 71a include MPU, CPU, and DSP. The storage unit 71b includes ROM and RAM. The storage unit 71b stores program codes or instructions configured to cause the processor 71a to execute processing. The receiver control device 71 may be configured by a hardware circuit such as ASIC or FPGA. The processing circuitry, receiver controller 71, may include one or more processors operating according to a computer program, one or more hardware circuits such as ASICs or FPGAs, or a combination thereof. ROM and RAM or computer-readable media include any available media that can be accessed by a general purpose or special purpose computer.

The receiving antenna 72 receives the radio signal transmitted from the transmitter 62 . The receiving circuit 73 demodulates the radio signal received via the receiving antenna 72 and obtains the detection signal of the acceleration sensor 61 . The receiving circuit 73 outputs the demodulated detection signal of the acceleration sensor 61 to the receiver control device 71 . Thereby, the receiver control device 71 acquires the detection signal of the acceleration sensor 61 . That is, the receiver 70 receives the detection signal of the acceleration sensor 61 transmitted from the transmitter 62 . The receiver control device 71 calculates the value of the acceleration G caused by the vibration of the main body 50 from the detection signal of the acceleration sensor 61 .

<Regarding loose wheel nuts>
Loosening of the wheel nut 20 will be described with reference to FIG. Loosening the wheel nut 20 means separating the wheel nut 20 from the wheel 14 so that the arm portion 52 is not sandwiched between the wheel nut 20 and the wheel 14 . Further, the loosening of the wheel nut 20 means that the positioning of the arm portion 52 with respect to the wheel nut 20 is released and the axial force generated by the wheel nut 20 is eliminated. The loosening of the wheel nut 20 means that the second surface 25 of the wheel nut 20 is separated from the first surface 522 b of the second portion 522 .

For example, assume that one of the six wheel nuts 20 that fix one wheel 14 to the axle 11 is loosened, as indicated by the two-dot chain line in FIG. When one of the six wheel nuts 20 is loosened, the arm 52 positioned against that wheel nut 20 tends to move between the wheel 14 and that wheel nut 20 . In the main body portion 50, the arm portions 52 positioned with respect to the five wheel nuts 20 that are not loosened are fixed ends, and the arm portions 52 positioned with respect to the loose wheel nuts 20 are free ends. becomes. Even if the arm portion 52 is positioned by the wheel nut 20, the arm portion 52 vibrates. and the wheel 14 easily vibrate.

Comparing before and after one wheel nut 20 is loosened, the vibration of the arm 52 positioned with respect to the wheel nut 20 is greater after the wheel nut 20 is loosened. Since the vibration of the arm portion 52 is transmitted to the base portion 51, the vibration of the body portion 50 becomes greater after the wheel nut 20 is loosened. Therefore, the vibration of the body portion 50 changes due to the change in the vibration of the arm portion 52 positioned on the wheel nut 20 . When the vibration of the body portion 50 changes, the acceleration G of the body portion 50 changes.

The acceleration sensor 61 detects a detection signal according to changes in vibration of the main body 50 . The acceleration sensor 61 is an example of a sensor configured to detect changes in behavior of the main body 50 . The acceleration sensor 61 detects looseness of the wheel nut 20 by detecting a change in behavior of the body portion 50 as a change in vibration of the body portion 50 . Note that even when one of the six wheel nuts 20 is loosened and a plurality of wheel nuts 20 are loosened, the acceleration sensor 61 detects a change in the behavior of the body portion 50 to detect changes in the behavior of the wheel nuts 20 . Detect looseness.

<Wheel nut looseness determination>
As shown in FIG. 5, receiver 70 monitors the amplitude of the value of acceleration G versus time. The receiver 70 determines looseness of the wheel nut 20 using the value of the acceleration G based on the detection signal of the acceleration sensor 61 transmitted from the transmitter 62 . The receiver control device 71 monitors whether or not the magnitude of the value of the acceleration G is greater than or equal to the threshold value g1 stored in the storage section 71b. The receiver control device 71 determines that none of the six wheel nuts 20 are loosened when the magnitude of the value of the acceleration G is less than the threshold value g1. The receiver control device 71 determines that at least one of the six wheel nuts 20 is loose when the value of the acceleration G is greater than or equal to the threshold value g1. The receiver control device 71 is an example of a determination unit that is provided in the receiver 70 and determines looseness of the wheel nut 20 based on the detection signal of the acceleration sensor 61 transmitted from the transmitter 62 . The threshold g1 is set so as not to exceed the amplitude of the value of the acceleration G when the vehicle 10 is running with the six wheel nuts 20 not loosened.

<Action of this embodiment>
The operation of this embodiment will be described.

Even if one of the six wheel nuts 20 is loosened, the vibration of the arm 52 positioned with respect to the wheel nut 20 changes. The change in vibration of the arm portion 52 changes the vibration of the body portion 50 . The acceleration sensor 61 detects looseness of the wheel nut 20 by detecting a change in behavior of the body portion 50 as a change in vibration of the body portion 50 .

<Effects of this embodiment>
Effects of the present embodiment will be described.

(1-1) A change in vibration of the arm portion 52 positioned with respect to the loosened wheel nut 20 results in a change in vibration of the body portion 50. Therefore, the acceleration sensor 61 detects a change in behavior of the body portion 50. It can be detected as a change in vibration of the body portion 50 . Therefore, it is possible to detect that the wheel nuts 20 are loose even if the plurality of wheel nuts 20 are not loose.

(1-2) The acceleration sensor 61 is provided at a position where the distances D1 from all wheel nuts 20 are the same. Therefore, fluctuations in the value of the acceleration G due to the rotation of the wheel 14 are suppressed. Therefore, the acceleration sensor 61 can accurately detect looseness of the wheel nut 20 as a change in vibration of the body portion 50 .

(1-3) When the wheel nut 20 becomes loose, the arm 52 positioned with respect to the wheel nut 20 becomes a free end. When the arm portion 52 as the free end vibrates between the wheel nut 20 and the wheel 14 , the vibration transmitted to the base portion 51 is amplified by the weight 60 . Therefore, even if one of the plurality of wheel nuts 20 is loosened, the vibration of the main body portion 50 becomes noticeable due to the weight 60 . Therefore, even if one of the plurality of wheel nuts 20 is loosened, the looseness of the wheel nut 20 can be easily detected by the acceleration sensor 61 .

[Second embodiment]
A looseness determination device and a bracket according to a second embodiment will be described. The main differences between this embodiment and the first embodiment are the structure of the bracket and the method of determining looseness of the wheel nut by the receiver control device. This point will be described below, and detailed description of the same configuration as that of the first embodiment will be omitted.

<Bracket structure>
FIG. 6 shows bracket 40 prior to securing body portion 50 to wheel 14 . Each of all the arm portions 52 is a single plate member with no bent portion. All arms 52 have insertion holes 522a. The arm portion 52 has a first surface 52a and a second surface 52b positioned opposite to the first surface 52a in the thickness direction of the arm portion 52 . The first surface 52a of the arm portion 52 and the first surface 51a of the base portion 51 are flush with each other. The second surface 52b of the arm portion 52 and the second surface 51b of the base portion 51 are flush with each other.

The bracket 40 has six strain sensors 66 in place of the acceleration sensor 61. Each of the six strain sensors 66 is attached to the base portion 51 and the arm portion 52 so as to straddle the boundary B between each arm portion 52 and the base portion 51 .

FIG. 7 shows the bracket 40 after fixing the body portion 50 to the wheel 14 . Six strain sensors 66 are electrically connected to transmitter 62 . Detection signals from the six strain sensors 66 are input to the transmitter 62 . The transmitter controller 63 inputs detection signals detected by the six strain sensors 66 to the transmission circuit 64 . The transmission circuit 64 transmits, from the transmission antenna 65, a radio signal modulated according to the detection signals of the six strain sensors 66 input from the transmitter control device 63. FIG. That is, the transmitter 62 transmits the detection signal of the strain sensor 66 to the receiver 70 . The detection signals of the six strain sensors 66 may be input to the transmitter 62 after being amplified by an amplifier.

All the arms 52 are bent toward the wheel 14 with respect to the base 51. All the arm portions 52 and base portions 51 are elastically deformed so as to be inclined relative to each other with the boundary B as a reference. All the arms 52 are elastically deformed to have a tip 52c that contacts the wheel 14. As shown in FIG. In the body portion 50 , a deformed portion P is defined as a portion that is elastically deformed at the boundary B. FIG. Each of the six strain sensors 66 is provided so as to straddle the deformation point P. As shown in FIG.

The hub bolts 13 are inserted through the insertion holes 522a of all the arm portions 52. A wheel nut 20 is fastened to the hub bolt 13 passing through the insertion hole 522a. As a result, all the arm portions 52 are fastened together with the wheel 14 by the wheel nuts 20 . The strain ε at the deformed portion P is larger at the boundary B than before the body portion 50 is elastically deformed. In a state in which all the arm portions 52 are fastened together with the wheel 14 , a restoring force is constantly acting on all the arm portions 52 to eliminate the strain ε of the deformed portion P.

<Regarding loose wheel nuts and loose wheel nuts>
Loosening of the wheel nut 20 will be described.

For example, assume that one of the six wheel nuts 20 that fix one wheel 14 to the axle 11 is loosened, as indicated by the two-dot chain line in FIG. When one of the six wheel nuts 20 is loosened, the arm portion 52 positioned with respect to the wheel nut 20 moves following the wheel nut 20 due to the restoring force. If one of the six wheel nuts 20 is loosened, the stress acting on the deformed portion P between the arm portion 52 positioned with respect to the wheel nut 20 and the base portion 51 is reduced.

Comparing before and after loosening of one wheel nut 20 shows that the strain ε of the deformed portion P between the arm portion 52 and the base portion 51 positioned with respect to the wheel nut 20 is the same as when the wheel nut 20 is loosened. After that, it becomes smaller. The strain sensor 66 provided on the arm portion 52 and the base portion 51 that has moved following the loosened wheel nut 20 detects a detection signal corresponding to the change in the strain ε of the deformed portion P. Note that the strain sensor 66 detects a change in the strain ε of the body portion 50 not only when one of the six wheel nuts 20 is loosened, but also when a plurality of wheel nuts 20 are loosened.

Next, assume that at least one of the six wheel nuts 20 is about to loosen. The fact that the wheel nut 20 is loosening means that the second surface 25 of the wheel nut 20 is separated from the wheel 14 while the arm portion 52 is sandwiched between the wheel nut 20 and the wheel 14 . Further, when the wheel nut 20 is loosened, it means that the axial force for fixing the wheel 14 to the axle 11 is generated, but the axial force is weakened compared to the case where the wheel nut 20 is not loosened. is.

When at least one of the six wheel nuts 20 is about to loosen, the stress acting on the deformed portion P between the arm portion 52 positioned with respect to the wheel nut 20 and the base portion 51 is reduced.

Comparing before and after the wheel nut 20 is about to loosen, the strain ε of the deformed portion P between the arm portion 52 positioned with respect to the wheel nut 20 and the base portion 51 is higher when the wheel nut 20 is about to loosen. become smaller. The strain sensor 66 provided on the arm portion 52 positioned with respect to the loose wheel nut 20 and the base portion 51 detects a detection signal according to the change in the strain ε of the deformed portion P.

Therefore, the elastic deformation of the body portion 50 changes due to the change in behavior of the arm portion 52 positioned on the wheel nut 20 . When the elastic deformation of the body portion 50 changes, the strain ε of the body portion 50 changes. The strain sensor 66 is an example of a sensor configured to detect changes in behavior of the body portion 50 . The strain sensor 66 detects the loosening of the wheel nut 20 or the loosening of the wheel nut 20 by detecting a change in the behavior of the body portion 50 as a change in the strain ε of the body portion 50 .

<Determination of wheel nut looseness and looseness of wheel nut>
After receiving the radio signal transmitted from the transmitter 62 , the receiver 70 demodulates the radio signal to obtain detection signals of the six strain sensors 66 . That is, the receiver 70 receives the detection signal of the strain sensor 66 transmitted from the transmitter 62 . The receiver 70 calculates the strain ε caused by the elastic deformation of the main body 50 from the demodulated detection signals of the six strain sensors 66 .

As shown in FIG. 8, the receiver 70 monitors changes in strain ε over time. The receiver 70 uses the value of the strain ε based on the strain sensor 66 transmitted from the transmitter 62 to determine whether the wheel nut 20 is loose or the wheel nut 20 is about to be loosened. The receiver control device 71 compares the strain ε value of each of the six strain sensors 66 with the first threshold value ε1 stored in the storage unit 71b. The receiver control device 71 determines that none of the six wheel nuts 20 are loosened when the value of the strain ε is the first threshold value ε1. When the value of the strain ε is smaller than the first threshold value ε1, the receiver control device 71 determines that at least one of the six wheel nuts 20 is loosened or at least one of the six wheel nuts 20 is about to be loosened. determined to be The first threshold value ε1 is the value of the strain ε acting on the deformed portion P when the six wheel nuts 20 are not loosened.

When the value of strain ε is smaller than the first threshold ε1, the receiver control device 71 determines whether or not the value of strain ε exceeds the second threshold ε2. The second threshold ε2 is smaller than the first threshold ε1. The receiver control device 71 determines that at least one of the six wheel nuts 20 is about to loosen when the value of the strain ε exceeds the second threshold value ε2. The receiver control device 71 determines that at least one of the six wheel nuts 20 is loosened when the value of the strain ε is equal to or less than the second threshold value ε2. The second threshold value ε2 is the value of the strain ε when the axial force generated by the loose wheel nut 20 disappears. The receiver control device 71 is an example of a determination unit that is provided in the receiver 70 and determines looseness of the wheel nut 20 based on the detection signal of the strain sensor 66 transmitted from the transmitter 62 .

<Action of this embodiment>
The operation of this embodiment will be described.

Even if one of the six wheel nuts 20 is loosened, the behavior of the arm 52 positioned with respect to the wheel nut 20 changes. The strain ε of the body portion 50 changes due to the change in behavior of the arm portion 52 . Moreover, even when the wheel nut 20 is about to loosen, the strain ε of the body portion 50 changes. Therefore, the strain sensor 66 detects looseness of the wheel nut 20 by detecting a change in behavior of the body portion 50 as a change in the strain ε of the body portion 50 . Further, the strain sensor 66 detects a looseness of the wheel nut 20 by detecting a change in the behavior of the body portion 50 as a change in the strain ε of the body portion 50 .

(2-1) When the wheel nut 20 is loosened or is about to be loosened, the strain ε of the body portion 50 changes. Therefore, the strain sensor 66 can detect changes in the behavior of the body portion 50 and changes in the strain ε of the body portion 50 . Therefore, even if the plurality of wheel nuts 20 are not loosened, it is possible to detect that the wheel nuts 20 are loosened or that the wheel nuts 20 are about to be loosened.

(2-2) Looseness of the wheel nut 20 is detected using the strain ε value based on the detection signal of the strain sensor 66 . Therefore, a change in stress acting on the deformed portion P of the body portion 50 can be detected through a change in the strain ε. Therefore, not only the looseness of the wheel nut 20 but also the looseness of the wheel nut 20 can be detected.

[Change example]
Each of the above embodiments can be implemented with the following modifications. Each of the above-described embodiments and modifications below can be implemented in combination with each other within a technically consistent range.

·Although the arm portion 52 is positioned with respect to the wheel nut 20 by being tightened together with the wheel 14 by the wheel nut 20, it may be changed, for example, as shown in FIG.

As shown in FIG. 9, the arm portion 52 has a through hole 53 with a size capable of accommodating the wheel nut 20 instead of the through hole 522a. An inner peripheral surface defining the through hole 53 is formed by a plurality of projections 54 . All protrusions 54 are provided on the entire circumference of the through hole 53 . All protrusions 54 are tapered toward the center of through hole 53 . The tips of all projections 54 are located on the same virtual circle. That is, the distances from the tips of all the protrusions 54 to the center of the through hole 53 are the same.

The wheel nut 20 is accommodated in the through hole 53 so as to overlap the arm portion 52. Each of the six corners 20 a of the wheel nut 20 is sandwiched by two of the multiple projections 54 . Two protrusions 54 out of the plurality of protrusions 54 are pressed against each of the six corners 20a. Of the plurality of protrusions 54 , the protrusions 54 that are not in contact with the corner portion 20 a are not in contact with the wheel nut 20 .

Thereby, the wheel nut 20 is positioned inside the through hole 53 . Accordingly, the arm portion 52 is positioned with respect to the wheel nut 20 while contacting the wheel nut 20 with the plurality of projections 54 .

· Although the wheel nut 20 is used as the fixing member, it may be changed as shown in FIG. 10, for example. Note that FIG. 10 is based on the first embodiment.

As shown in FIG. 10, a bolt 80 is adopted in place of the wheel nut 20. The bolt 80 penetrates the wheel 14 and the hub 12 while being inserted through the insertion hole 522 a of the arm portion 52 . The hub 12 is provided with a plurality of screw holes 12a through which the bolts 80 are inserted. All threaded holes 12a have female threads into which male threads of bolts 80 are screwed. All the screw holes 12a are preferably spaced apart from each other around the axis m1 of the axle 11 . Even with such a change, the wheel 14 is fixed to the axle 11 by screwing the bolts 80 into the screw holes 12a at a plurality of locations around the axis m1 of the axle 11 . The bolt 80 is an example of a fixing member that has a male thread and generates an axial force for fixing the wheel 14 to the axle 11 . Note that the second embodiment may be similarly modified. Further, the arm portion 52 may be positioned with respect to the bolt 80 while contacting the head portion of the bolt 80 by means of a plurality of projections 54 as in the modified example described above.

· In the first embodiment, the acceleration sensor 61 is provided on the axis m1 of the axle 11, but the present invention is not limited to this. For example, the acceleration sensor 61 may be provided on each arm 52 .

When changing in this way, looseness of each wheel nut 20 may be determined by whether or not the amplitude of the acceleration G based on the detection signal of each acceleration sensor 61 is greater than or equal to the threshold value g1.

Looseness of the wheel nut 20 may also be determined by comparing values of the acceleration G based on detection signals of the acceleration sensors 61 . Specifically, it may be determined that the wheel nut 20 positioning the arm portion 52 having a relatively large value of the acceleration G is loosened. Therefore, the receiver control device 71 only needs to be able to determine looseness of the wheel nut 20 or the bolt 80 based on the detection signal of the acceleration sensor 61 transmitted from the transmitter 62 .

· In the first embodiment, the looseness of the wheel nut 20 is determined by the receiver control device 71, but the present invention is not limited to this. For example, looseness of the wheel nut 20 may be determined by the transmitter control device 63 . In this case, the determination result by the transmitter controller 63 may be changed to be transmitted to the receiver 70 . When changing in this way, the transmitter 62 is changed to include the acceleration sensor 61 . The transmitter control device 63 calculates the value of the acceleration G of the main body 50 from the detection signal of the acceleration sensor 61 and uses the value of the acceleration G to determine looseness of the wheel nut 20 . That is, the transmitter control device 63 may be a determination unit that determines looseness of the wheel nut 20 based on the detection signal of the acceleration sensor 61 .

The transmitter control device 63 inputs the determination result data to the transmission circuit 64 . The transmission circuit 64 transmits a radio signal modulated according to the data from the transmission antenna 65 to the receiver 70 . In other words, the transmitter 62 may be changed to conform to the specifications of a TPMS (Tire Pressure Monitoring System) transmitter. Note that even if the fixing member is changed from the wheel nut 20 to the bolt 80 , the looseness of the bolt 80 may be determined by the transmitter control device 63 .

· In the second embodiment, looseness of the wheel nut 20 may be determined by comparing the strain ε values based on the detection signals of the strain sensors 66 . Specifically, when there is a deformed portion P where the value of the strain ε is relatively small, it is determined that the wheel nut 20 positioning the arm portion 52 including the deformed portion P is loosened. You can change it to Therefore, the receiver control device 71 only needs to be able to determine looseness of the wheel nut 20 or the bolt 80 based on the detection signal of the strain sensor 66 transmitted from the transmitter 62 .

· In the second embodiment, the looseness of the wheel nut 20 is determined by the receiver control device 71, but the present invention is not limited to this. For example, looseness of the wheel nut 20 may be determined by the transmitter control device 63 . That is, the transmitter control device 63 may be a determination unit that determines looseness of the wheel nut 20 based on the detection signal of the strain sensor 66 . In this case, the determination result by the transmitter control device 63 may be changed to be transmitted to the receiver 70 . Note that even if the fixing member is changed from the wheel nut 20 to the bolt 80 , the looseness of the bolt 80 may be determined by the transmitter control device 63 .

· Although the strain sensor 66 is provided on the arm portion 52 and the base portion 51 so as to straddle the boundary B, it is not limited to this. For example, the strain sensor 66 may be provided at a location where the arm portion 52 is elastically deformed to bring the tip portion 52c into contact with the wheel 14 . That is, the strain sensor 66 may be provided only on the arm portion 52 . Therefore, the strain sensor 66 should be attached to at least the arm portion 52 of the base portion 51 and the arm portion 52 .

· In the second embodiment, before fixing the body portion 50 to the wheel 14 , all the arm portions 52 may be bent so that the tip portion 52 c that contacts the wheel 14 is provided in advance. Similarly, all arms 52 and bases 51 may be pre-bent so as to be inclined with respect to boundary B before fixing body 50 to wheel 14 . When the main body portion 50 is deformed in advance, the degree of deformation of the main body portion 50 is such that when the main body portion 50 is fixed to the wheel 14, the arm portion 52 is elastically deformed so as to bring the deformation portion P and the tip portion 52c into contact with the wheel 14. It is to the extent that the restoring force acts on the part where it is moved.

· In the second embodiment, the shape of the arm portion 52 when elastically deformed may be changed as appropriate. For example, when fixing the body portion 50 to the wheel 14, the arm portion 52 may be elastically deformed in a bow shape. The strain sensor 66 is preferably attached to a portion of the arm portion 52 that is elastically deformed in a bow shape. As in the modification described above, the arm portion 52 may be previously deformed into a bow shape before the main body portion 50 is fixed to the wheel 14 . When the arm portion 52 is deformed in advance, the degree of deformation of the arm portion 50 is such that when the main body portion 50 is fixed to the wheel 14, a restoring force acts on the portion elastically deformed in a bow shape.

· The strain sensor 66 does not have to be provided on all the arms 52 , as long as it is provided on at least one of the plurality of arms 52 .

· The looseness determination device 30 may include a determination device as a determination unit that determines whether the wheel nut 20 or the bolt 80 is loose or almost loose, apart from the transmitter 62 and the receiver 70 . The determination device determines looseness of the wheel nut 20 or the bolt 80 based on a detection signal from a sensor configured to detect a change in behavior of the body portion 50 .

The bracket 40 may include the main body 50 and a sensor configured to detect changes in behavior of the main body 50, such as the acceleration sensor 61 or the strain sensor 66, and may not include the transmitter 62. . When modified in this way, the vehicle is also not equipped with a receiver 70 . Therefore, the bracket 40 may have a determination device for determining looseness of the wheel nut 20 or the bolt 80 . Note that the bracket 40 may omit the determination device described above, and may include at least the main body 50 and a sensor such as the acceleration sensor 61 or the strain sensor 66 .

· The wheel nut 20 is not limited to a cap nut, and may be a nut having a threaded hole penetrating in its axial direction.

DESCRIPTION OF SYMBOLS 11... Axle, 14... Wheel, 20... Wheel nut, 30... Looseness determination apparatus, 40... Bracket, 50... Body part, 51... Base part, 52... Arm part, 61... Acceleration sensor, 62... Transmitter, 66... Strain Sensor, 70 -- Receiver, 80 -- Volt, D1 -- Distance, m1 -- Axle axis, G -- Acceleration, ε -- Strain.

Claims

A bracket configured to be mounted on a wheel, comprising:
The wheel is fixed to the axle by screwing male and female threads at each of a plurality of fastening points around the axis of the axle,
A fixing member is a member having the male thread or the female thread and generating an axial force for fixing the wheel to the axle,
The bracket is
in the main body,
a base positioned in extension of the axle;
an arm extending radially from the base toward each of the fixing members positioned at the plurality of fastening points and positioned with respect to the fixing member while being in contact with the fixing member;
a sensor configured to detect changes in behavior of the body.
The sensor is an acceleration sensor,
2. The bracket according to claim 1, wherein said acceleration sensor is provided at a position where the distances from all said fixing members are the same.
The sensor is a strain sensor provided on at least one of the arms,
2. The bracket according to claim 1, wherein said strain sensor is attached to at least said arm of said base and said arm.
The bracket according to any one of claims 1 to 3, comprising a transmitter configured to transmit a detection signal of the sensor.
A looseness determination device that determines looseness of a fixing member that generates an axial force for fixing a wheel to an axle,
The wheel is fixed to the axle by screwing male and female threads at each of a plurality of fastening points around the axis of the axle,
the fixing member has the male thread or the female thread,
The looseness determination device is
A bracket configured to be mounted on the wheel, comprising:
a base positioned on the extension of the axle; and a base extending radially from the base towards each of the fixing members positioned at the plurality of fastening locations, and positioned with respect to the fixing member while being in contact with the fixing member. a main body having an arm, and
a sensor configured to detect a change in behavior of the body;
a bracket comprising a transmitter; and
a receiver configured to receive a signal transmitted from the transmitter;
and a determination unit configured to determine looseness of the fixing member based on a detection signal of the sensor.
The sensor is an acceleration sensor,
6. The looseness determination device according to claim 5, wherein said acceleration sensor is provided at a position where the distances from all said fixing members are the same.
7. The looseness determining device according to claim 6, wherein said determining unit is provided in said receiver and configured to determine looseness of said fixing member based on a detection signal of said acceleration sensor transmitted from said transmitter. .
The sensor is a strain sensor provided on at least one of the arms,
The strain sensor is attached to at least the arm of the base and the arm,
6. The looseness determining device according to claim 5, wherein said determining unit is provided in said receiver and configured to determine looseness of said fixing member based on a detection signal of said strain sensor transmitted from said transmitter. .