Wheel nut loosening detector

Abstract

To provide a wheel nut loosening detector which can achieve reduction of manufacturing costs, can eliminate expensive modification costs even used for an existing large automobile, can be easily handled and eliminate necessity of visual observation before travel, and can allow a driver or the like to notice a situation in which a wheel nut loosens even during driving a large automobile.SOLUTION: A loosening detector is used for a large automobile 1 and has a sensor unit 100. The sensor unit has: a housing 11; a nut ring 61 which has an annular part 61a rotating in synchronization with a wheel nut 37; and a first control unit 15. The first control unit 15 comprises: detection parts 15c, 15d which output a detection signal when the annular part 61a rotates in synchronization with the wheel nut 37 rotating in a loosening direction; a transmission part 38 capable of transmitting an alarm signal to a receiver 200 by the detection signal; and first control units 15a, 15b for controlling the detection parts 15c, 15d and the transmission part 38.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a device for detecting looseness of wheel nuts used in large automobiles. [Background technology]

[0002] Large vehicles such as medium-sized trucks, large trucks, and tourist buses have multiple pairs of hubs and multiple pairs of wheels fixed to each hub. Six, eight, or ten wheel bolts are fixed to each hub, and the axles of each wheel bolt protrude horizontally toward the outside of the vehicle. A tire is assembled to each wheel to form a wheel. Each wheel is provided with wheel bolt holes in the same number as the wheel bolts, and each axle is inserted into each wheel bolt hole and screwed in by a wheel nut. In this manner, the wheels are fixed to each hub.

[0003] The left and right rear wheels may each have one wheel fixed to the left and right hubs (single wheel), or as shown in Figure 27, an inner wheel 97 and an outer wheel 99 are fixed (double wheel). That is, the left and right front wheels are each fixed to the left and right hubs by one wheel, while the left and right rear wheels are each fixed to the left and right hubs 93 by two wheels 97, 99.

[0004] In the case of a double wheel, the hub mounting portion 97a of the inner wheel 97 has the same number of wheel bolt holes 97b as the wheel bolts 95, and the hub mounting portion 97a protrudes toward the outside of the vehicle body. A tire 92 is attached to the inner wheel 97, and the wheel 97 and the tire 92 constitute the inner wheel W1. The hub mounting portion 99a of the outer wheel 99 also has the same number of wheel bolt holes 99b as the wheel bolts 95, and the hub mounting portion 99a protrudes toward the inside of the vehicle body. A tire 94 is attached to the outer wheel 99, and the wheel 99 and the tire 94 constitute the outer wheel W2. A wheel nut 98 is screwed onto the shaft portion 95a of each wheel bolt 95 inserted through the wheel bolt hole 97b of the hub mounting portion 97a and the wheel bolt hole 99b of the outer wheel 99, respectively, via a washer 96. In this way, the inner wheel W1 and the outer wheel W2 are fixed to one hub 93.

[0005] In recent years, there has been an increase in accidents involving large vehicles in which one of the wheel nuts loosens while the vehicle is moving, causing the wheel to fall off. The left wheel is particularly prone to falling off, and the wheels of double wheels are even more prone to falling off. For this reason, loosening detection devices have been proposed, for example, as described in Patent Documents 1 to 3.

[0006] The wheel nut loosening detection devices in Patent Documents 1 and 2 consist of an annular part that is coaxial with the axis of the shaft part and an indicator extending from the annular part. The annular part is attached to the wheel nut so as to be synchronously rotatable with the wheel nut. A loosening detection device in which two annular parts are connected by an indicator is also known.

[0007] In these wheel nut loosening detection devices, the annular portion is attached to the wheel nut when the wheel nut is properly screwed onto the axle. If the large vehicle travels a certain distance and one of the wheel nuts loosens from the axle, the annular portion rotates in synchronization with that wheel nut. In this case, the direction pointed by the indicator and the shape of the indicator change from the state before the wheel nut loosened, so that the driver of the large vehicle can visually check the indicator before driving and know that the wheel nut is loose before the vehicle comes off. Therefore, the driver can retighten the loosened wheel nut before driving, thereby preventing the wheel from falling off.

[0008] The wheel nut loosening detection device of Patent Document 3 includes a sensor unit having a ring-shaped spacer-like member extending around the entire circumference of the hub, and an information processing device. The spacer-like member is provided with wheel bolt holes having the same number as the wheel bolts of the hub, and each shaft portion is inserted into the wheel bolt holes and screwed with a wheel nut. The spacer-like member is provided with a strain sensor between each wheel bolt hole. The sensor unit is also provided with a battery that supplies power to each strain sensor, and a first communication device. The information processing device has a second communication device that can communicate with the first communication device of the sensor unit, and has a fastening state determination means that determines an abnormality in the fastening state of each wheel nut from the detection data of the strain sensor. The information processing device also has a display unit.

[0009] In this wheel nut loosening detection device, the sensor unit is, for example, sandwiched between the hub and the wheel of the vehicle, and is attached by correctly screwing each wheel nut onto each axle. The information processing device is mounted in the cab of a large vehicle. When the large vehicle has traveled a certain distance and any one of the wheel nuts has loosened from the axle, the detection data of each strain sensor of the sensor unit is transmitted by the first communication device to the second communication device of the information processing device. In the information processing device, the fastening state determination means determines whether the fastening state of the wheel nut is abnormal based on each detection data, and a display unit that may be mounted in the cab displays this result. Therefore, the driver, etc. can know whether the wheel nut is loose by checking the determination result even while driving. Therefore, the driver, etc. can prevent the wheel from falling off by tightening the wheel nut before driving. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Utility Model Registration No. 3146831 [Patent Document 2] Patent No. 5706985 [Patent Document 3] Patent No. 6466223 Summary of the Invention [Problem to be solved by the invention]

[0011] However, in the wheel nut loosening detection devices of Patent Documents 1 and 2, the driver cannot see the indicator while the large vehicle is traveling. Therefore, the driver cannot notice the wheel nut loosening while traveling. In addition, in the case of a double wheel rear wheel, the axle protrudes outward, so it is difficult for the driver to even see the indicator located below the axle before traveling.

[0012] On the other hand, in the wheel nut loosening detection device of Patent Document 3, the driver or the like can notice the wheel nut loosening while driving by checking the display unit. However, in this loosening detection device, the sensor unit uses a strain sensor that is affected by temperature, so it is necessary to install a temperature sensor to detect the temperature, which is likely to result in a rise in manufacturing costs.

[0013] In addition, because this loosening detection device utilizes the tightening force of the spacer-like member generated by the wheel bolt and wheel nut, if it is used on an existing large vehicle, the wheel bolts will need to be replaced, which will require expensive modification costs.

[0014] Furthermore, with this loosening detection device, whenever the tightening torque of the wheel nuts is checked during a statutory inspection or the wheel nuts are retightened and the numerical value of the strain sensor changes, the reference value must be reset, making the device cumbersome to use.

[0015] The present invention has been made in consideration of the above-mentioned conventional situation, and has as its object to provide a wheel nut loosening detection device which can reduce manufacturing costs, does not require expensive modification costs when used on existing large vehicles, is easy to handle, does not require visual inspection before driving, and enables the driver or other person in charge to notice if the wheel nuts become loose even while the large vehicle is driving. [Means for solving the problem]

[0016] The wheel nut loosening detection device of the present invention is used in large automobiles and is a wheel nut loosening detection device equipped with a sensor unit, The large vehicle has a hub to which a plurality of wheel bolts are fixed and from which shafts of the wheel bolts protrude; a wheel to which a tire is attached to form a wheel, the wheel having wheel bolt holes formed therethrough in the same number as the wheel bolts, and the shaft portions being inserted into the wheel bolt holes and screwed together with wheel nuts, the wheel being fixed to the hub; the sensor unit includes a housing through which at least two adjacent shaft portions are inserted and which is fixed to the wheel by screwing each of the shaft portions with the wheel nuts; a nut ring that is concealed by the housing and has an annular portion that is coaxial with an axis of each of the shaft portions, and is attached to each of the wheel nuts so that each of the annular portions can rotate synchronously with each of the wheel nuts; The first control device is provided within the housing, includes a battery, and operates using power from the battery, and is characterized by having a detection unit that outputs a detection signal when the annular portion rotates in synchronization with the wheel nut rotating in the loosening direction, a transmission unit that is capable of transmitting a warning signal to a receiver based on the detection signal, and the first control unit that controls the detection unit and the transmission unit.

[0017] In the wheel nut loosening detection device of the present invention, when the wheel nut rotates on the hub in the direction of loosening, the nut ring in the sensor unit also rotates in synchronization with the wheel nut. Therefore, in the first control device, the detection unit outputs a detection signal, and the transmission unit transmits a warning signal to the receiver.

[0018] If the receiver is installed in the cab of a large vehicle, the driver can notice if the wheel nuts come loose even while driving. If the receiver is located at the base of the large vehicle, it is possible to know if the wheel nuts of the large vehicle come loose at the base. There is no need to visually check before driving.

[0019] Furthermore, this wheel nut loosening detection device does not require a temperature sensor, which allows for reduced manufacturing costs.

[0020] Furthermore, this wheel nut loosening detection device does not require replacement of wheel bolts and can be used as is on existing large automobiles, eliminating the need for expensive modification costs.

[0021] Furthermore, in this wheel nut loosening detection device, the detection unit outputs a detection signal simply by rotating the annular portion in sync with the wheel nut rotating in the loosening direction, so there is no need to reset the first control unit even if the tightening torque of the wheel nut is checked or the wheel nut is further tightened, making it easy to use.

[0022] Therefore, the wheel nut loosening detection device of the present invention makes it possible to reduce manufacturing costs, does not require expensive modification costs when used on existing large vehicles, is easy to handle, does not require visual inspection before driving, and enables drivers and others to notice if the wheel nuts have loosened even while the large vehicle is driving.

[0023] In the wheel nut loosening detection device of the present invention, the large vehicle includes a medium-sized truck with a total vehicle weight of less than 8 tons, a large truck with a total vehicle weight of 11 tons or more and a maximum load capacity of 6.5 tons or more, and a tourist bus with a passenger capacity of 30 or more. The present invention is particularly effective when used with large vehicles whose wheel bolt standards are the new ISO method, and is even more effective when used with the rear wheels of twin wheels on large vehicles.

[0024] The housing of the sensor unit is inserted through at least two adjacent shaft parts. This eliminates the need for a rotation stopper on the housing. The housing may be inserted through two adjacent shaft parts, three adjacent shaft parts, or four or more adjacent shaft parts. Since six, eight, or ten wheel bolts are fixed to each hub of a large vehicle, the housing may be inserted through six, eight, or ten adjacent shaft parts. When the housing is inserted through two or more shaft parts, the housing is rectangular or arc-shaped in plan view, but when the housing is inserted through the shaft parts of all the wheel bolts fixed to the hub, the housing is annular in plan view. The housing is fixed to the wheel by screwing the shaft parts of the wheel bolts with wheel nuts.

[0025] The nut ring has an annular portion that forms a ring shape coaxial with the axis of the shaft portion of the wheel bolt. The nut ring is attached to the wheel nut so that the annular portion can rotate synchronously with the wheel nut. Therefore, when the wheel nut rotates in the direction that loosens it, the annular portion also rotates synchronously in the same direction. Because the nut ring is concealed in the housing, the nut ring is not affected even if a pebble or the like hits the loosening detection device while the large vehicle is traveling. In addition, because the housing is prevented from rotating by at least two adjacent shaft portions, there is no need to prevent the nut ring itself from rotating.

[0026] The first control unit of the first control device can be an I / O interface, a storage device, a CPU, etc. In particular, if a processor with a built-in I / O interface is used as the first control unit, it is easy to realize a compact sensor unit.

[0027] The battery for the first control device can be a 3 to 12 V alkaline or lithium battery, such as those used in doorbells and other open / close sensors. The battery is preferably a button type. In this case, it is easy to reduce the size of the sensor unit.

[0028] The detection unit of the first control device may be a magnetic sensor that is provided so as to be able to approach or move away from the permanent magnet without contacting it, or a mechanical switch that is provided so as to be able to come into contact with the pressing unit and be able to be pressed or not pressed, or the like.

[0029] The transmitting unit may be a wireless LAN slave device capable of wirelessly transmitting radio waves of a specific frequency. The transmitting unit may also be one that transmits to a receiver via Bluetooth (registered trademark) or Wi-Fi.

[0030] The receiver may be dedicated to the wheel nut loosening detection device, or may be used for other purposes such as a smartphone. When a receiver dedicated to the loosening detection device is used, the transmitter of the sensor unit and the receiver of the receiver may be paired to communicate by radio waves of a specific frequency. Since the sensor unit rotates together with the wheels while traveling, it is preferable that the communication is wireless. When the large vehicle is a long body, trailer, articulated vehicle, etc., and the distance between the transmitter and the receiver is long and communication is difficult, a repeater may be provided between the transmitter and the receiver. When a receiver used for other purposes such as a smartphone is used, the transmitter of the sensor unit and the receiver of the receiver may be configured to wirelessly communicate by paired Bluetooth (Bluetooth (registered trademark)) or Wi-Fi. In this case, a repeater may also be provided between the transmitter and the receiver. When a smartphone is used, an application that configures the receiver and the notification unit is installed in the smartphone.

[0031] The wheel nut loosening detection device preferably includes a receiver. The receiver may include a second control device that is operated by an external power source. The second control device preferably includes a receiving unit that receives a warning signal, a notification unit that notifies the driver of loosening of any one of the wheel nuts by the warning signal, and a second control unit that controls the receiving unit and the notification unit. In this case, by mounting the receiver in the driver's cab of a large vehicle, the driver can be made aware of the loosening of a wheel nut even while driving by the notification from the receiver.

[0032] The second control device is operated by an external power source. The external power source may be a battery of a large vehicle, a battery of a smartphone, or the like. The second control unit of the second control device may be an I / O interface, a storage device, a CPU, or the like. The second control device may be an in-vehicle Wi-Fi router or a mobile Wi-Fi router for connecting the large vehicle to the Internet and making Wi-Fi available in the driver's cab, etc.

[0033] The receiving unit may be a wireless LAN master unit capable of receiving radio waves of a specific frequency. The receiving unit may be a unit that wirelessly receives radio waves from the transmitting unit via Bluetooth (registered trademark) or Wi-Fi.

[0034] The notification unit can be a display device that indicates the loosening of any one of the wheel nuts or the battery life using light or display in response to a warning signal, or a warning device that warns of the loosening of any one of the wheel nuts or the battery life using a warning sound or voice or other sound in response to a warning signal.

[0035] A large vehicle has four or more wheels, and six, eight, or ten wheel bolts are fixed to each hub. Therefore, for example, when the housing of the sensor unit is inserted into two axles, three, four, or five sensor units are provided on one wheel. When a large number of sensor units are provided on one large vehicle in this way, each sensor unit has a transmitter. Therefore, it is preferable that the transmitter and receiver are paired. In this case, the receiver can identify which sensor unit's transmitter has transmitted a warning signal, and the notification unit can identify which wheel is at risk of falling off. Then, the driver can quickly tighten the wheels after stopping the large vehicle.

[0036] As the magnetic sensor, a Hall element, a magnetic reed switch, a coil, or a magnetoresistance element (MR) can be used. As the magnetoresistance element, a semiconductor magnetoresistance element (SMR), an anisotropic magnetoresistance element (AMR), a giant magnetoresistance element (GMR), a tunnel magnetoresistance element (TMR), etc. can be used. These are preferably provided in an IC having a circuit such as an amplifier. In addition, the magnetic sensor is resistant to shocks.

[0037] Each nut ring preferably includes a permanent magnet fixed to an annular portion, and the detection unit is a Hall element that outputs a detection signal in response to a change in the magnetism of each permanent magnet. The Hall element uses the Hall effect, which generates a Hall voltage in response to a magnetic field, and the Hall voltage can be amplified by an amplifier to output a detection signal. By using a Hall IC having a Hall element and an amplifier circuit, the sensor unit can be made smaller.

[0038] It is preferable that the first control unit causes the transmitting unit to transmit a warning signal if the detection value of at least one of the detection signals is lower than a first threshold value. When a Hall element is used as the magnetic sensor, the detection signal is output as a voltage value. When a magnetic resistance element is used as the magnetic sensor, the detection signal is output as a resistance value. By comparing these detection values ​​with the first threshold value, the accuracy of detecting loosening of the wheel nuts is improved.

[0039] It is preferable that the first control unit goes into the low power mode when the detection value is higher than the first threshold, and goes into the normal power mode when the detection value is lower than the first threshold. In this case, the sensor unit requires less large power, and the battery life can be secured.

[0040] The magnetic sensor is preferably a magnetic reed switch that outputs a detection signal by switching between a conductive state and a non-conductive state as a permanent magnet approaches or moves away from the wheel nut. When a magnetic reed switch is used that switches from a non-conductive state to a conductive state as a permanent magnet approaches the wheel nut when the wheel nut is loosened, a detection signal can be output in the conductive state. When a magnetic reed switch is used that switches from a conductive state to a non-conductive state as a permanent magnet moves away from the wheel nut when the wheel nut is loosened, a detection signal can be output in the non-conductive state.

[0041] It is also preferable that each annular portion includes a pressing portion capable of pressing the detection portion, and the detection portion is a mechanical switch that outputs a detection signal by switching between a conductive state and a non-conductive state depending on whether the pressing portion is pressed or not. In this case, when a mechanical switch is adopted in which the pressing portion of the annular portion presses the detection portion when the wheel nut is loosened, switching from a non-conductive state to a conductive state, a detection signal can be output in the conductive state. When a mechanical switch is adopted in which the pressing portion of the annular portion does not press the detection portion when the wheel nut is loosened, switching from a conductive state to a non-conductive state, a detection signal can be output in the non-conductive state.

[0042] The first control unit preferably causes the transmitting unit to transmit a specific signal if the battery voltage is lower than the second threshold. Also, the second control unit preferably causes the notifying unit to notify the battery life if the receiving unit receives the specific signal. In this case, the driver or the like can be made aware of the battery life by the notification from the receiver.

[0043] It is preferable that the first control unit goes into the low power mode when the battery voltage is higher than the second threshold, and goes into the normal power mode when the battery voltage is lower than the second threshold. In this case, the sensor unit also requires less power, and the battery life can be secured.

[0044] It is preferable that the annular portion of each nut ring is rotatable and adjustable around its axis. In this case, when the nut ring is attached to the wheel nut, even if the permanent magnet or the pressing portion of the annular portion is not in a suitable position with respect to the detection portion, it is possible to adjust the permanent magnet or the pressing portion to a suitable position with respect to the detection portion by rotating the annular portion.

[0045] The annular portion may be rotatably adjustable in both directions, that is, in the direction in which the wheel nut is loosened and in the direction in which the wheel nut is retightened. In this case, after the ring is attached to the nut, the permanent magnet or the pressing portion can be rotated from the side closest to the suitable position, so that the rotation angle is small and the adjustment can be completed quickly.

[0046] It is preferable that each nut ring is capable of rotating and adjusting the annular portion around the axis only in the direction in which the wheel nut is loosened. In this case, the operating force required for rotating and adjusting the nut ring can be reduced. If the wheel nut becomes loose in this state, the nut ring reliably rotates together with the wheel nut, and the loosening of the wheel nut can be reliably detected. In order to allow the nut ring to rotate only in the direction in which the wheel nut is loosened, a ratchet mechanism can be provided in the nut ring.

[0047] It is also preferable that each nut ring is capable of adjusting its annular portion around the axis only in the direction in which the wheel nuts are tightened. In this case, the wheel nuts are not loosened when adjusting the rotation of the nut ring. In order to allow the nut ring to rotate only in the direction in which the wheel nuts are tightened, a ratchet mechanism can be provided in the nut ring.

[0048] The first control device may be housed in a case. The case is preferably held in a sealed state in the housing. In this case, the battery, the magnetic sensor, the transmitter, and the first control unit are sealed, and the battery and other components are unlikely to be damaged even if the sensor unit and the wheel come into contact with water.

[0049] The housing preferably comprises a base plate that is fixed to the wheel by screwing each shaft part with a wheel nut, and a cover plate that fits to the base plate with the case sandwiched between the base plate and the case, and hides each nut ring. In this case, it is easy to provide the case, the battery in the case, the magnetic sensor, the transmitter, and the first controller in the sensor unit.

[0050] It is preferable that the hexagonal portion of each wheel nut is exposed when the sensor unit is attached. In this case, it is possible to retighten the wheel nut with the sensor unit attached. Also, it is possible to check the looseness of the wheel nut by checking the striking sound of the hexagonal portion. Effect of the Invention

[0051] The wheel nut loosening detection device of the present invention can realize low manufacturing costs, does not require expensive modification costs even when used on existing large vehicles, is easy to handle, does not require visual inspection before driving, and allows the driver to notice the wheel nut loosening even while the large vehicle is driving. Therefore, if the driver notices that the wheel nut is loose, he or she can prevent the wheel from falling off by tightening the wheel nut before driving. [Brief description of the drawings]

[0052] [Figure 1] FIG. 1 is a side view of a large truck equipped with a wheel nut loosening detection device according to any one of the first to eighth embodiments. [Diagram 2] FIG. 2 is a side view of a wheel to which a sensor unit of a wheel nut loosening detection device according to any one of the first to eighth embodiments is attached. [Diagram 3] FIG. 3 is a perspective view of a sensor unit in the wheel nut loosening detection device according to the first embodiment. [Figure 4] FIG. 4 is an exploded perspective view of a sensor unit in the wheel nut loosening detection device according to the first embodiment. [Diagram 5] FIG. 5 is a perspective view of a nut ring in the wheel nut loosening detection device according to the first embodiment. [Figure 6] FIG. 6 is a block diagram of a sensor unit board in the wheel nut loosening detection device according to the first embodiment. [Figure 7] FIG. 7 is a perspective view of a dedicated receiver in the wheel nut loosening detection device according to the first embodiment. [Figure 8] FIG. 8 is an exploded perspective view of a dedicated receiver in the wheel nut loosening detection device according to the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view of a wheel etc. to which a sensor unit of the wheel nut loosening detection device according to the first embodiment is attached. [Figure 10] FIG. 10 is a block diagram of a dedicated receiver board in the wheel nut loosening detection device according to the first embodiment. [Figure 11] FIG. 11 is a schematic front view showing the relationship between the wheel bolt, the nut ring, and the first Hall IC in the wheel nut loosening detection device in the first embodiment. [Figure 12] FIG. 12 is a schematic front view showing the relationship between the wheel bolt, the nut ring, and the second Hall IC in the wheel nut loosening detection device according to the first embodiment. [Figure 13] FIG. 13 is a flow chart showing a main routine executed by a processor in the wheel nut loosening detection device according to the first embodiment. [Figure 14] FIG. 14 is a flowchart showing a subroutine executed by a processor in the wheel nut loosening detection device according to the first embodiment. [Figure 15]FIG. 15 is a schematic front view showing the relationship between the wheel bolt, the nut ring, and the magnetic reed switch in the wheel nut loosening detection device in the second embodiment. [Figure 16] FIG. 16 is a schematic front view showing the relationship between the wheel bolt, the nut ring, and the magnetic reed switch in the wheel nut loosening detection device in the second embodiment. [Figure 17] FIG. 17 is an exploded perspective view of an outer member of a nut ring in a wheel nut loosening detection device according to a third embodiment. [Figure 18] FIG. 18 is an exploded perspective view of an inner member of a nut ring in a wheel nut loosening detection device according to the third embodiment. [Figure 19] FIG. 19 is an enlarged sectional view of a nut ring as viewed from outside in a wheel nut loosening detection device according to the third embodiment. [Figure 20] FIG. 20 is a schematic front view showing the relationship between the wheel bolt, the nut ring, and the microswitch in the wheel nut loosening detection device according to the fourth embodiment. [Figure 21] FIG. 21 is a perspective view of a nut ring in a wheel nut loosening detection device according to the fifth embodiment. [Figure 22] FIG. 22 is a schematic front view showing the relationship between the wheel bolt, the nut ring, and the microswitch in the wheel nut loosening detection device according to the fifth embodiment. [Figure 23] FIG. 23 is a perspective view of a nut ring in a wheel nut loosening detection device in the sixth embodiment. [Figure 24] FIG. 24 is a schematic front view showing the relationship between the wheel bolt, the nut ring, and the microswitch in the wheel nut loosening detection device in the sixth embodiment. [Diagram 25] FIG. 25 is a perspective view of a nut ring in the wheel nut loosening detection device according to the seventh embodiment. [Figure 26] FIG. 26 is a perspective view of a nut ring in the wheel nut loosening detection device according to the eighth embodiment. [Figure 27]FIG. 27 is an exploded perspective view of a dual wheel of a large truck. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Hereinafter, embodiments 1 to 8 of the present invention will be described with reference to the drawings.

[0054] Example 1 The wheel nut loosening detection device in the first embodiment is provided on a large truck 1 shown in Fig. 1. The large truck 1 has a front wheel Wf, a first rear wheel Wr1, and a second rear wheel Wr2 on the left and right sides. The loosening detection device comprises a total of 24 sensor units 100 and a single dedicated receiver 200 provided in the driver's cab. That is, as shown in Fig. 2, there are four sensor units 100 on the right front wheel Wf of the vehicle, four on the left front wheel Wf, four on the right first rear wheel Wr1, four on the left first rear wheel Wr1, four on the right second rear wheel Wr2, and four on the left second rear wheel Wr2.

[0055] The large truck 1 has a hub 3a for the front wheels, a hub 3b for the first rear wheel, and a hub 3c for the second rear wheel, on the left and right sides respectively. Eight wheel bolts 5 conforming to the new ISO standard are fixed to each of the hubs 3a-3c. The shaft portion 5a of each wheel bolt 5 protrudes horizontally toward the outside of the vehicle. Each wheel bolt 5 is originally provided on the large truck 1, similar to the wheel bolt 95 shown in FIG. 27.

[0056] As shown in FIG. 2, a wheel 7a is fixed to both hubs 3a, wheels 7b and 7c are fixed to both hubs 3b, and wheels 7d and 7e are fixed to both hubs 3c. That is, the first rear wheel Wr1 and the second rear wheel Wr2 are double wheels. FIG. 9 shows an example of a double wheel, and the hub mounting portion 7f of each of the wheels 7b to 7e is provided with wheel bolt holes 9, the same number as the wheel bolts 5. The same applies to each wheel 7a of the single wheel. Each of the wheels 7a to 7e is designed so that the shaft portion 5a of the wheel bolt 5 is inserted into the wheel bolt hole 9. The wheels 7a to 7e, like the wheels 97 and 99 in FIG. 27, were originally provided on the large truck 1 together with the tires 92 and 94.

[0057] Each sensor unit 100 is fixed to the hub mounting portion 7f of the wheels 7a to 7e. The washer 36 and the wheel nut 37 are originally provided on the large truck 1, similar to the washer 96 and the wheel nut 98 in FIG.

[0058] 3 and 4, each sensor unit 100 includes a unit housing 11, a case 13, a sensor unit substrate 15, and two nut rings 61. Note that wheels 7a to 7e are not shown in FIGS. 3 and 4.

[0059] As shown in Fig. 4, the unit housing 11 is made of a base plate 21 and a cover plate 23. The base plate 21 is a metal plate material such as stainless steel with a thickness of about 1 mm, and is formed in an arc-shaped eyeglass shape with both ends. A first insertion hole 21a is formed in one end of the base plate 21, through which the shaft portion 5a of the wheel bolt 5 is inserted. In addition, a second insertion hole 21b is formed in the other end of the base plate 21, through which the shaft portion 5a of the adjacent wheel bolt 5 is inserted.

[0060] At both edges of the central portion of the base plate 21, a plate material is bent at a right angle by press forming to form held walls 21c and 21d extending parallel to each other. Locking holes 21e and 21f are formed through the held walls 21c and 21d by press forming, respectively. In addition, a notched locking portion 21g is formed at the central portion of the base plate 21 by press forming.

[0061] Case 13 is composed of a resin dish-shaped case body 25 and a resin case cap 27. Case body 25 is adapted to be locked to locking portion 21g of base plate 21. Case cap 27 is formed with window 27a that allows light to pass through. Sensor unit substrate 15 is housed between case body 25 and case cap 27. Case body 25 and case cap 27 are sealed with a sealing material with sensor unit substrate 15 including battery 35 housed therein.

[0062] The sensor unit 100 has two nut rings 61. As shown in FIG. 5, each nut ring 61 has an annular portion 61a made of resin. The annular portion 61a is annular and coaxial with the axis X of the shaft portion 5a. A number of inclined plates 61b are provided integrally with the annular portion 61a on the inner circumference of the annular portion 61a. Each inclined plate 61b is inclined to one side in the circumferential direction of the annular portion 61a. The inclination direction of each inclined plate 61b has an inclination angle θ extending leftward with respect to a normal line n extending from the axis X when the nut ring 61 is viewed from the outside.

[0063] Moreover, a bulge 61c is provided integrally with the annular portion 61a on the inner periphery of the annular portion 61a. A permanent magnet 33 is insert-molded in the bulge 61c. Moreover, a marking M is formed on the side surface of the annular portion 61a where the bulge 61c is located.

[0064] In this nut ring 61, each inclined plate 61b constitutes a ratchet mechanism. That is, the nut ring 61 can be manually rotated only in the direction U, which is the same as the inclination angle θ, relative to the wheel nuts 37. On the other hand, if the wheel nuts 37 are retightened, the nut ring 61 also rotates synchronously in the direction R opposite to the direction U. On the other hand, if the wheel nuts 37 are loosened, the nut ring 61 also rotates synchronously in the direction U.

[0065] The sensor unit board 15 shown in Fig. 4 corresponds to the first control device. As shown in Fig. 6, the sensor unit board 15 has a processor 15a with a built-in I / O interface, a memory device 15b, and first and second Hall ICs 15c and 15d. The memory device 15b and the first and second Hall ICs 15c and 15d are connected to the processor 15a. In addition, in the sensor unit board 15, a battery 35, a transmitter 38, and an LED 39 are connected to the processor 15a. The battery 35 is button-shaped. The LED 39 is provided at a position that aligns with the window 27a of the case 13.

[0066] The first and second Hall ICs 15c and 15d have Hall elements 41 and 43 as magnetic sensors, and an amplifier circuit (not shown) that amplifies the Hall voltage generated by the Hall elements 41 and 43 due to the magnetic field. The first and second Hall ICs 15c and 15d are arranged on both ends of the sensor unit board 15, i.e., on both ends of the case 13. The memory device 15b stores a program and a sub-code number, which will be described later. The processor 15a and the memory device 15b constitute a first control unit.

[0067] As shown in FIG. 4, the cover plate 23 is a metal plate material such as stainless steel having a thickness of about 0.5 mm, and both ends are formed in an arc-shaped eyeglass shape. A first insertion hole 23a is formed at one end of the cover plate 23, through which the hexagonal portion 37a of the wheel nut 37 is inserted and which is smaller than the nut ring 61. A second insertion hole 23b is formed at the other end of the cover plate 23, through which the hexagonal portion 37a of the wheel nut 37 is inserted and which is smaller than the nut ring 61. The first insertion hole 23b is coaxial with the first insertion hole 21a of the base plate 21, and the second insertion hole 23a is coaxial with the second insertion hole 21b of the base plate 21. Ribs 23j and 23k are formed around the first and second insertion holes 23a and 23b in the cover plate 23 to protrude outward in order to increase the strength of those parts.

[0068] At both edges of the center portion of the cover plate 23, a metal plate is bent at a right angle by press forming to form holding walls 23c, 23d extending parallel to each other. The holding walls 23c, 23d are configured to sandwich the held walls 21c, 21d of the base plate 21 from the outside by elastic deformation. Locking projections 23e, 23f are respectively provided through the holding walls 23c, 23d by press forming. The locking projections 23e, 23f are inserted into the locking holes 21e, 21f of the base plate 21 by elastic deformation of the holding walls 23c, 23d, and can be engaged with the locking holes 21e, 21f by elastic return of the holding walls 23c, 23d.

[0069] Windows 23g, 23h, and 23i are also formed by press molding in the center of the cover plate 23. The window 23g is aligned with the window 27a of the case 13. The windows 23h and 23i are designed so that the marking M of the nut ring 61 can be confirmed.

[0070] In this manner, the sensor units 100 are attached to the front wheel Wf, the first rear wheel Wr1, and the second rear wheel Wr2. In this state, the sensor units 100 expose the hexagonal portions 37a of the wheel nuts 37, as shown in Figs.

[0071] As shown in FIGS. 7 and 8, the dedicated receiver 200 includes a receiver housing 42, a receiver board 44, a mounting base 45, a double-sided tape 47, and a USB cable 49.

[0072] The mounting base 45 is attached to the wall surface inside the driver's cab with double-sided tape 47. An arm 45a is provided to protrude from the mounting base 45. A spherically recessed receiving surface 45b is formed at the tip of the arm 45a.

[0073] The receiver housing 42 is composed of a resin dish-shaped receiver body 51 and a resin receiver cap 53. A spherical joint 51a that can engage with a receiving surface 45b of the arm 45a is provided on the back surface of the receiver body 51. By sliding the spherical joint 51a within the receiving surface 45b, the driver or assistant in the cab can change the position of the receiver housing 42 to make it easier for them to see.

[0074] The receiver cap 53 has a plurality of windows 53a and an opening 53b formed therethrough. A cover 53c is fixed inside each window 53a. A button 53d is provided in the opening 53b so as to be movable in and out of the receiver cap 53. The receiver board 44 is housed between the receiver body 51 and the receiver cap 53. The receiver body 51 and the receiver cap 53 are fastened together with screws 55 with the receiver board 44 housed therein.

[0075] The receiver board 44 shown in Fig. 8 corresponds to the second control device. As shown in Fig. 10, the receiver board 44 has a processor 44a with an I / O interface built in, a storage device 44b, a receiving unit 44c, a display device 44d, and a reset button 44e. The storage device 44b, the receiving unit 44c, the display device 44d, and the reset button 44e are connected to the processor 44a. The display device 44d is composed of a green LED 46a, a yellow LED 46b, and a red LED 46c. The display device 44d can be seen by the driver, etc. through the windows 53a of the receiver housing 42 through each cover 53c. The display device 44d corresponds to the notification unit. The reset button 44e can be pressed by the driver, etc. via the button 53d.

[0076] A USB cable 49 is connected to the receiver board 44, and power is supplied to the receiver board 44 from a battery of a large vehicle as an external power source. A program to be described later and a parent code number are stored in the memory device 44b. The parent code number is paired with the child code number of each sensor unit 100. The processor 44a and the memory device 44b constitute a second control unit.

[0077] When fixing each sensor unit 100 to the hub mounting portion 7f of the wheels 7a to 7e, first, as shown in FIG. 9, the shaft portion 5a of each wheel bolt 5 protruding from the hubs 3a to 3c is inserted into the wheel bolt hole 9 of the wheels 7a to 7e, and the hub mounting portion 7f of the wheels 7a to 7e is provided on the wheel mounting portion 3d of the hubs 3a to 3c. Next, adjacent shaft portions 5a are inserted into the first and second insertion holes 21a and 21b of the base plate 21 of the unit housing 11 in the sensor unit 100, and wheel nuts 37 are screwed to both shaft portions 5a via washers 36. The case 13 containing the sensor unit board 15 is fixed to the base plate 21. Both wheel nuts 37 are tightened with a set torque.

[0078] Thereafter, nut rings 61 are provided on the outer peripheral surfaces of the hexagonal portions 37a of adjacent wheel nuts 37. Then, both shaft portions 5a are inserted into the first and second insertion holes 23a, 23b of the cover plate 23, the held walls 21c, 21d of the base plate 21 are sandwiched between the holding walls 23c, 23d, and the locking projections 23e, 23f are engaged with the locking holes 21e, 21f. In this manner, each sensor unit 100 is fixed to the hub mounting portion 7f of the wheels 7a to 7e without using screws.

[0079] In the sensor unit board 15 of each sensor unit 100, the processor 15a executes the program shown in Fig. 13 by a switch (not shown). First, in step S1, initialization is performed. At this time, the green LED 46a of the receiver board 44 in the dedicated receiver 200 emits light.

[0080] In this state, as shown in Fig. 11, the permanent magnet 33 of one nut ring 61 is separated from the Hall element 41 of the first Hall IC 15c on the sensor unit board 15, as shown in Fig. 12, the permanent magnet 33 of the other nut ring 61 is separated from the Hall element 43 of the second Hall IC 15d on the sensor unit board 15, or if both are separated from the Hall elements 41, 43, the LED 39 emits red light. Also, the red LED 46c of the receiver board 44 in the dedicated receiver 200 emits light. Note that the inclined plates 61b of the nut ring 61 are not shown in Figs. 11 and 12.

[0081] 11, when the permanent magnet 33 is in position A, for example, the nut ring 61 is manually rotated only in direction U relative to the wheel nut 37 to bring the permanent magnet 33 of the bulging portion 61c closer to the Hall element 41. It can be confirmed that the bulging portion 61c is in the vicinity of the Hall element 41 by the presence of the marking M in the window 23h. At this time, the nut ring 61 rotates only in direction U relative to the wheel nut 37, and does not rotate in direction R opposite to direction U.

[0082] 12, when the permanent magnet 33 is in position B, the nut ring 61 is manually rotated only in direction U relative to the wheel nut 37 to bring the permanent magnet 33 at the bulge 61c closer to the Hall element 43. The presence of the marking M in the window 23i also enables confirmation that the bulge 61c is in the vicinity of the Hall element 43. In this case, the nut ring 61 rotates only in direction U relative to the wheel nut 37, and does not rotate in direction R opposite to direction U. This reduces the operating force required to rotate and adjust the nut ring 61.

[0083] When the permanent magnets 33 of all the sensor units 100 approach the Hall elements 41 , 43 , the child code numbers of the sensor units 100 are wirelessly transmitted from the transmitting section 38 to the receiving section 44 c of the dedicated receiver 200 .

[0084] Meanwhile, the driver or assistant in the cab connects the USB cable 49 of the dedicated receiver 200 to the USB port of the vehicle and presses the reset button 44e using the button 53d. This causes the processor 44a to receive each sub-code number with the receiver 44c and perform pairing. This allows the dedicated receiver 200 to identify which sensor unit 100's transmitter 38 has transmitted the warning signal. If the distance between each transmitter 38 and the receiver 44c is long, a repeater is provided in the vehicle body. This completes the initialization.

[0085] Thereafter, the processor 15a goes into the low power mode in step S2 shown in Fig. 13. As a result, the LED 39 goes out and the transmission unit 38 goes into a standby state.

[0086] While the driver is driving the large truck, the cover plate 23 protects both nut rings 61 and the sensor unit board 15 in the case 13 from stones and the like. Then, in all sensor units 100, the processor 15a waits for the input of at least one detection signal in step S3 with the Hall ICs 15c, 15d not in contact with the permanent magnet 33. In step S4, the processor 15a determines whether the voltage of the detection signal is equal to or lower than the first threshold. If the voltage of the detection signal is not equal to or lower than the first threshold (NO), the process returns to step S3 and waits for the input of at least one detection signal.

[0087] 11 and 12, when one or more wheel nuts 37 rotate in the loosening direction U on any of the hubs 3a to 3c, the nut ring 61 in the sensor unit 100 fastened by that or those wheel nuts 37 also rotates in synchronization with the wheel nuts 37. At this time, since the unit housing 11 is prevented from rotating by the two adjacent shaft portions 5a, there is no need to prevent the nut ring 61 itself from rotating.

[0088] Since the nut ring 61 rotates, the permanent magnet 33 also rotates in synchronization with the wheel nut 37, and is located at, for example, position C. At this time, in the sensor unit 100, the permanent magnet 33 moves away from the Hall elements 41, 43, and the magnetic field weakens, so that the Hall voltage drops. Therefore, in step S4 shown in FIG. 13, the voltage of the detection signal becomes equal to or lower than the first threshold (YES). As a result, in the sensor unit 100, the mode returns to the normal power mode in step S5, and the transmitter 38 is restored. In addition, in step S6, a warning signal is transmitted to the receiver 44c. Then, in step S7, the LED 39 emits red light.

[0089] In the dedicated receiver 200, the receiving section 44c receives the warning signal. As a result, the red LED 46c of the receiver board 44 emits light. The processor 44a can be configured to identify which sensor unit 100 has transmitted the warning signal by each sub-code number, and display one of the hubs 3a to 3c on the display device 44d. In this case, the driver or the like can notice which of the wheels 7a, 7c, 7e has the loosened wheel nut 37 even while driving.

[0090] Therefore, the driver or the like can immediately stop the large vehicle, visually confirm that one or both wheel nuts 37 of the sensor unit 100 whose LED 39 is lit red are loose, and retighten these wheel nuts 37. At this time, since the hexagonal portion 37a of each wheel nut 37 is exposed when the sensor unit 100 is attached, it is possible to retighten the wheel nuts 37 with the sensor unit 100 attached. In addition, it is also possible to confirm the looseness of the wheel nuts 37 by checking the striking sound of the hexagonal portion 37a. Note that a warning device may be employed that warns of the loosening of any one of the wheel nuts 37 by a warning signal using a warning sound, voice, or other sound.

[0091] Furthermore, this loosening detection device does not require a temperature sensor, which allows for reduced manufacturing costs.

[0092] Furthermore, this loosening detection device does not require replacement of each wheel bolt 5 and can be used as is on existing large automobiles, so there is no need for expensive modification costs.

[0093] In addition, in this loosening detection device, the Hall ICs 15c and 15d output detection signals simply when the magnetism of the permanent magnet 33 changes, so there is no need to reset the first control unit even when checking the fastening torque of the wheel nuts 37 or tightening the wheel nuts 37, making the device easy to use. The Hall ICs 15c and 15d are also resistant to impacts.

[0094] Therefore, this loosening detection device makes it possible to reduce manufacturing costs, does not require expensive modification costs when used on existing large vehicles, is easy to use, does not require visual inspection before driving, and enables the driver or other person in charge to notice if the wheel nut 37 becomes loose even while the large vehicle is driving.

[0095] Therefore, if the driver or the like notices that the wheel nuts 37 are loose, the driver or the like can retighten the wheel nuts 37 before driving, thereby preventing the front wheels Wf, the first rear wheel Wr1, and the second rear wheel Wr2 from falling off. Furthermore, this loosening detection device allows the wheel nuts 37 to be retightened before the wheels 7a-7e become loose, thereby preventing damage to the wheel bolts 5 and the wheels 7a-7e. This makes it possible to achieve high safety and excellent economy.

[0096] In addition, in this loosening detection device, each processor 15a proceeds to step S11 shown in Fig. 14, and goes into a low power mode in which steps S12 and S13 are performed every few hours. In step S12, the voltage of the battery 35 is measured, and in step S13, it is determined whether the voltage of the battery 35 is equal to or lower than the second threshold value. If the voltage of the battery 35 is not equal to or lower than the second threshold value (NO), the process returns to step S12 and waits for the voltage measurement.

[0097] In step S13, if the voltage of the battery 35 is equal to or lower than the second threshold (YES), the mode returns to normal power mode in step S14 and the transmitter 38 is restored, and in step S15, a specific signal is transmitted to the receiver 44c. When the receiver 44c receives the specific signal, the yellow LED 46b on the receiver board 44 in the dedicated receiver 200 emits light. This allows the driver or the like to know the remaining life of the battery 35 by the notification from the dedicated receiver 200. In addition, in step S16, the process returns to the flowchart of FIG. 13. It is to be noted that a warning device may be employed that warns of the remaining life of the battery 35 by a warning signal using a warning sound, voice, or the like.

[0098] Therefore, the driver or the like can remove the cover plate 23 of the sensor unit 100 and replace the battery 35 in the case 13. The processor 44a can also be configured to identify which sensor unit 100 has transmitted a specific signal by each sub-code number and display that sensor unit 100 on the display device 44d. In this case, the driver or the like can notice which sensor unit 100 has reached the end of its battery 35 life.

[0099] Furthermore, the first control unit goes into the low power mode if the voltage of at least one detection signal is higher than the first threshold or the voltage of the battery 35 is higher than the second threshold, and goes into the normal power mode if the voltage of the detection signal is lower than the first threshold or the voltage of the battery 35 is lower than the second threshold. This reduces the need for large power in each sensor unit 100, ensuring the durability of the battery 35.

[0100] Furthermore, in this loosening detection device, each nut ring 61 is rotatable and adjustable around the axis X. Therefore, when attaching the nut ring 61 to the wheel nut 37, even if the permanent magnet 33 is not in a suitable position relative to the Hall elements 41, 43, the nut ring 61 can be rotated and adjusted to a suitable position relative to the Hall elements 41, 43.

[0101] In particular, in this loosening detection device, the nut rings 61 can be adjusted to rotate about the axis X only in the direction in which the wheel nuts 37 loosen. This makes it possible to reduce the operating force required to rotate and adjust the nut rings 61. If the wheel nuts 37 loosen in this state, the nut rings 61 reliably rotate together with the wheel nuts 37, and the loosening of the wheel nuts 37 can be reliably detected.

[0102] In addition, in this loosening detection device, the sensor unit board 15 is stored in the case 13, and the case 13 is held in a sealed state in the unit housing 11. Therefore, the battery 35, the processor 15a, the memory device 15b, the Hall ICs 15c and 15d, and the transmitter 38 are sealed, and the battery 35 and other components are unlikely to be damaged even if the sensor unit 100 together with the wheel comes into contact with water.

[0103] Furthermore, in this loosening detector, since the unit housing 11 is made up of the base plate 21 and the cover plate 23, the case 13 and the battery 35 in the case 13 and the like can be easily provided in the sensor unit 100.

[0104] Example 2 In the loosening detection device of the second embodiment, a magnetic reed switch 63 shown in Fig. 15 and Fig. 16 is used as a magnetic sensor instead of the first and second Hall ICs 15c and 15d. The magnetic reed switch 63 is enclosed in a glass tube 63a with a gap between them at the position where the reeds 63b and 63c overlap. The other configurations are the same as those of the first embodiment.

[0105] In this loosening detection device, as shown in FIG. 15, when the wheel nut 37 is properly screwed onto the shaft portion 5a and the permanent magnet 33 of the nut ring 61 is close to the magnetic reed switch 63, the reeds 63b and 63c are attracted to each other and become conductive.

[0106] On the other hand, as shown in Fig. 16, when the wheel nut 37 loosens and the permanent magnet 33 of the nut ring 61 moves away from the magnetic reed switch 63, the reeds 63b and 63c move away from each other and become non-conductive. The non-conductive state allows a detection signal to be output. Other functions and effects are the same as those of the first embodiment.

[0107] It is also possible to configure the system so that when the wheel nut 37 loosens, the leads 63b, 63c become conductive, and in this state the processor 15a or the like outputs a detection signal.

[0108] Example 3 In the loosening detection device of the third embodiment, a nut ring 17 shown in FIGS.

[0109] The nut ring 17 is composed of a resin outer member 29 shown in FIG. 17 and a resin inner member 31 shown in FIG. 18. The outer member 29 is composed of an annular portion 29a that is coaxial with the axis X of the shaft portion 5a, and a bulge portion 29b provided on a part of the annular portion 29a. Internal teeth 29c are formed on the inner peripheral surface of the annular portion 29a. As shown in FIG. 17, each tooth surface of the internal teeth 29c is inclined to one side in the circumferential direction of the annular portion 29a. The inclination direction of each tooth surface has an inclination angle θ' extending leftward with respect to a normal line n extending from the axis X when the nut ring 17 is viewed from the outside.

[0110] 17, a flange 29d extending radially inward is formed on the outer surface of the annular portion 29a. The bulging portion 29b protrudes from the opposite side to the flange 29d, that is, from the inside of the nut ring 17, parallel to the axis X. A permanent magnet 33 is insert-molded into the bulging portion 29b. Also, a marking M (not shown) is formed on the outer surface of the bulging portion 29b.

[0111] As shown in FIG. 18, the inner member 31 has a hexagonal frame 31a. As shown in FIG. 19, the frame 31a is aligned with the outer peripheral surface of the hexagonal portion 37a of the wheel nut 37. Each side of the frame 31a is provided with a claw portion 31b. Each claw portion 31b extends radially outward from each side of the frame 31a, and then extends in the inclined direction of the tooth surface of the internal tooth 29c, with the tip raised radially outward. The tip of each claw portion 31b can mesh with the tooth bottom of the internal tooth 29c. Also, as shown in FIG. 18, at each corner of the frame 31a, a plate-shaped guide plate 31c extends radially outward from the inner surface of the frame 31a. Each guide plate 31c is located inside the nut ring 17.

[0112] The inner member 31 is inserted into the outer member 29 from the inside of the annular portion 29a of the outer member 29 and assembled to form the nut ring 17. The sensor unit 100 has two nut rings 17. The flange 29d is located between the inner member 31 and the cover plate 23, and each guide plate 31c is located between the outer member 29 and the washer 36. Each guide plate 31c does not interfere with the bulging portion 29b, and the bulging portion 29b is located radially outward of the washer 36.

[0113] In this nut ring 17, as shown in FIG. 19, the internal teeth 29c of the external member 29 and each claw portion 31b form a ratchet mechanism. That is, the tip of each claw portion 31b meshes with the internal teeth 29c, but when the nut ring 17 is viewed from the outside, the tooth surface of the internal teeth 29c is inclined at an inclination angle θ' extending leftward with respect to the normal line n, and each claw portion 31b extends in the same direction as the inclination angle θ'. Therefore, the external member 29 can be manually rotated only in the same direction U as the inclination angle θ' with respect to the internal member 31 fixed to the hexagonal portion 37a of the wheel nut 37. On the other hand, if the wheel nut 37 is further tightened and the internal member 31 rotates synchronously in the direction R opposite to the direction U, the external member 29 also rotates synchronously in the direction R. On the other hand, if the wheel nut 37 is loosened and the internal member 31 rotates synchronously in the direction U, the external member 29 also rotates synchronously in the direction U.

[0114] When fixing each sensor unit 100 to the hub mounting portion 7f of the wheels 7a to 7e, the outer member 29 is assembled to the inner member 31 while fitting the frame 31a of the inner member 31 onto the outer peripheral surfaces of the hexagonal portions 37a of adjacent wheel nuts 37, and the nut ring 17 is provided. The other configurations are the same as those of the first embodiment.

[0115] In this loosening detector, the outer member 29 of the nut ring 17 can be manually rotated relative to the inner member 31 only in the direction U, and the permanent magnet 33 of the bulging portion 29b can be brought closer to the Hall elements 41, 43.

[0116] In addition, in this loosening detection device, the nut ring 17 is composed of two parts, but when the frame body 31a of the inner member 31 fits into the hexagonal portion 37a of the wheel nut 37, the outer member 29 rotates preferably in only one direction relative to the inner member 31, allowing the ratchet mechanism to exhibit excellent performance. Other functions and effects are the same as those of the first embodiment.

[0117] Example 4 The loosening detection device of the fourth embodiment employs a nut ring 18 shown in Fig. 20. This nut ring 18 has a pressing portion 29e that protrudes parallel to the axis X, instead of the bulging portion 29b of the outer member 29 in the nut ring 17 of the third embodiment. No permanent magnet 33 is provided on the pressing portion 29e. Note that detailed illustration of the nut ring 18 is omitted in Fig. 20.

[0118] Further, instead of the first and second Hall ICs 15c and 15d, the sensor unit board 15 is provided with first and second micro switches 15e (only one of which is shown) as mechanical switches. The first and second micro switches 15e have a pressed portion 15f, and are in a conductive state when the pressed portion 15f is pressed by the pressing portion 29e, and are in a non-conductive state when the pressed portion 15f is not pressed by the pressing portion 29e. The other configurations are the same as those of the third embodiment.

[0119] In this loosening detection device, when the wheel nut 37 is loosened and the pressing portion 29e of the outer member 29 no longer presses the pressed portion 15f of the first and second microswitches 15e, a detection signal can be output in a non-conductive state. Other functions and effects are the same as those of the first embodiment.

[0120] When the wheel nut 37 loosens, the pressing portion 29e of the external member 29 presses the pressed portions 15f of the first and second microswitches 15e, resulting in a conductive state, and it is also possible to configure the processor 15a, etc. to output a detection signal in this state.

[0121] Example 5 The loosening detection device of the fifth embodiment employs a nut ring 62 shown in Fig. 21. This nut ring 62 has a pressing portion 62a formed in the nut ring 61 of the first embodiment. The nut ring 62 is not provided with a permanent magnet 33. The other configurations are the same as those of the first and fourth embodiments.

[0122] In this loosening detection device, as shown in Fig. 22, when the wheel nut 37 loosens and the pressing portion 62a of the nut ring 62 no longer presses the pressed portion 15f of the first and second microswitches 15e, a detection signal can be output in a non-conductive state. Other functions and effects are the same as those of the first and fourth embodiments.

[0123] When the wheel nut 37 loosens, the pressing portion 62a of the nut ring 62 presses the pressed portions 15f of the first and second microswitches 15e, resulting in a conductive state, and it is also possible to configure the processor 15a, etc. to output a detection signal in this state.

[0124] Example 6 The loosening detection device of the sixth embodiment employs a nut ring 64 shown in Fig. 23. This nut ring 64 has a radially recessed non-pressing portion 64a instead of the bulging portion 61c in the nut ring 61 of the first embodiment. Therefore, the portion of the nut ring 61 other than the non-pressing portion 64a serves as a pressing portion 64b. The nut ring 64 does not have a permanent magnet 33. The other configurations are the same as those of the first and fourth embodiments.

[0125] In this loosening detection device, when the wheel nut 37 loosens and the pressing portion 64b of the nut ring 64 presses the pressed portion 15f of the first and second microswitches 15e, a detection signal can be output in a conductive state, as shown in Fig. 24. Other functions and effects are the same as those of the first and fourth embodiments.

[0126] When the wheel nut 37 loosens, the pressing portion 64b of the nut ring 64 no longer presses the pressed portion 15f of the first and second microswitches 15e, resulting in a non-conductive state. It is also possible to configure the processor 15a, etc. to output a detection signal in this state.

[0127] Example 7 The loosening detection device of the seventh embodiment employs a nut ring 66 shown in Fig. 25. This nut ring 66 has a pressing portion 66b formed on an annular portion 66a, which protrudes parallel to the axis X, and a notch 66c. In this way, even if the annular portion 66a has the notch 66c, it is sufficient that the annular portion 66a is annular.

[0128] Also, minute irregularities 66d are formed on the inner peripheral surface of the annular portion 66a. The nut ring 66 does not have an inclined plate 61b as in the first embodiment. Also, the nut ring 66 does not have a permanent magnet 33. The other configurations are the same as those in the first, fourth and fifth embodiments.

[0129] In this loosening detection device, the annular portion 66a exerts a frictional force against the outer peripheral surface of the wheel nut 37 due to the unevenness 66d, but the annular portion 66a can be manually rotated and adjusted in both directions around the axis X. At this time, the unevenness 66d reliably applies a frictional force against the outer peripheral surface of the wheel nut 37 due to the notch 66c. Therefore, when the nut ring 66 is attached to the wheel nut 37, even if the pressing portion 66b is not in a suitable position relative to the first and second microswitches 15e, it is possible to rotate the annular portion 66a in both directions to adjust the pressing portion 66b to a suitable position relative to the first and second microswitches 15e. Other functions and effects are the same as those of the first embodiment.

[0130] Example 8 The loosening detection device of the eighth embodiment employs a nut ring 68 shown in Fig. 26. The nut ring 68 has two arc-shaped outer members 70a and two arc-shaped inner members 70b connected by two connection parts 70c, 70d. The outer members 70a and the inner members 70b form annular shapes, and the inner members 70b are disposed within the outer members 70a. The connection parts 70c, 70d are located in the diametrical direction of the outer members 70a and the inner members 70b. The outer members 70a and the inner members 70b correspond to the annular part 68a.

[0131] The connecting portion 70d is formed with a pressing portion 68b that protrudes parallel to the axis X. Also, the inner peripheral surface of the inner member 70b is formed with projections and recesses 68c that fit with the corners of the hexagonal portion 37a of the wheel nut 37. The nut ring 68 is not provided with the inclined plate 61b as in the first embodiment. Also, the nut ring 68 is not provided with a permanent magnet 33. The other configurations are the same as those of the first, fourth and fifth embodiments.

[0132] In this loosening detection device, both inner members 70b of the annular portion 68a are fitted into the respective corners of the hexagonal portion 37a of the wheel nut 37 by the projections and recesses 68c while being bent, but the bending of both inner members 70b allows the annular portions 68a to be manually adjusted in both directions around the axis X. Other functions and effects are similar to those of the first embodiment.

[0133] (Modification) In the first to eighth embodiments, the dedicated receiver 200 is used as the receiver. However, instead of the dedicated receiver 200, a smartphone on which an application that configures a receiving section and a notifying section is installed can also be used as the receiver.

[0134] In the above, the present invention has been described based on Examples 1 to 8 and modified examples. However, the present invention is not limited to the above-mentioned Examples 1 to 8 and modified examples, and it goes without saying that the present invention can be applied with appropriate modifications without departing from the spirit of the present invention.

[0135] For example, the nut ring 17 of the third embodiment can be used together with the magnetic reed switch 63. Also, the nut rings 66 and 68 of the seventh and eighth embodiments can be provided with a permanent magnet 33 and used as a magnetic sensor. [Industrial Applicability]

[0136] The present invention can be used in a wheel derailment prevention device for a large truck. [Explanation of symbols]

[0137] 1. Large vehicles (large trucks) 100…Sensor unit 5…Wheel bolts 5a...Shaft part 3a~3c…Hub Wf, Wr1, Wr2...Wheels (Wf...Front wheel, Wr1...First rear wheel, Wr2...Second rear wheel) 37…Wheel nut 7a~7e…Wheels 9…Wheel bolt holes 11...Housing (unit housing) X…Axis center 61a, 29a, 66a, 68a...Annular portion 61, 17, 18, 62, 64, 66, 68…Nut ring 35...battery 15...First control device (sensor unit board) 41, 43, 63, 15e…Detection unit 200…Receiver 38...Transmitter 15a, 15b...first control unit (15a...processor, 15b...storage device) 44...Second control device (receiver board) 44c…Receiver 44d...Notification unit (display device) 44a, 44b... second control unit (44a... processor, 44b... storage device) 33...Permanent magnet 41, 43, 63...magnetic sensor (41, 43...hall element, 63...magnetic reed switch) 29e, 62a, 64b, 66b, 68b...Pressing section 15e…Mechanical switch (micro switch) 13…Case 21…Base plate 23…Cover plate 37a…Hexagonal part

Claims

1. A wheel nut loosening detection device for use in a large vehicle, the device comprising a sensor unit, The large vehicle has a hub to which a plurality of wheel bolts are fixed and from which shafts of the wheel bolts protrude; a wheel to which a tire is attached to form a wheel, the wheel having wheel bolt holes formed therethrough in the same number as the wheel bolts, and the shaft portions being inserted into the wheel bolt holes and screwed together with wheel nuts, the wheel being fixed to the hub; the sensor unit includes a housing through which at least two adjacent shaft portions are inserted and which is fixed to the wheel by screwing each of the shaft portions with the wheel nuts; a nut ring that is concealed by the housing and has an annular portion that is coaxial with an axis of each of the shaft portions, and is attached to each of the wheel nuts so that each of the annular portions can rotate synchronously with each of the wheel nuts; A wheel nut loosening detection device characterized in that it has a first control device that is provided within the housing, includes a battery, and operates using power from the battery, the first control device having a detection unit that outputs a detection signal when the annular portion rotates in sync with the wheel nut rotating in the loosening direction, a transmission unit that is capable of transmitting a warning signal to a receiver in response to the detection signal, and the first control unit that controls the detection unit and the transmission unit.

2. The wheel nut loosening detection device includes the receiver, The receiver includes a second control device that is powered by an external power source; The wheel nut loosening detection device according to claim 1, wherein the second control device has a receiving unit that receives the warning signal, a notification unit that notifies of loosening of any one of the wheel nuts in response to the warning signal, and a second control unit that controls the receiving unit and the notification unit.

3. The wheel nut loosening detection device according to claim 2 , wherein the transmitting unit and the receiving unit are paired.

4. Each of the nut rings includes a permanent magnet secured to the annular portion; 3. The wheel nut loosening detection device according to claim 1, wherein the detection portion is a magnetic sensor that outputs the detection signal in response to a change in magnetism of each of the permanent magnets.

5. 5. The wheel nut loosening detection device according to claim 4, wherein the magnetic sensor is a Hall element that outputs the detection signal in response to a change in magnetism of each of the permanent magnets.

6. The wheel nut loosening detection device according to claim 5 , wherein the first control unit causes the transmission unit to transmit the warning signal when a detection value of at least one of the detection signals is lower than a first threshold value.

7. The wheel nut loosening detection device according to claim 6 , wherein the first control unit goes into a low power mode when the detection value is higher than the first threshold value, and goes into a normal power mode when the detection value is lower than the first threshold value.

8. 5. The wheel nut loosening detection device according to claim 4, wherein the magnetic sensor is a magnetic reed switch which alternates between a conductive state and a non-conductive state depending on whether the permanent magnet approaches or moves away from the magnetic sensor, thereby outputting the detection signal.

9. Each of the annular portions includes a pressing portion capable of pressing the detection portion, 3. The wheel nut loosening detection device according to claim 1, wherein the detection portion is a mechanical switch which alternates between a conductive state and a non-conductive state depending on whether the pressing portion is pressed or not, and outputs the detection signal.

10. The first control unit causes the transmission unit to transmit a specific signal if the voltage of the battery is lower than a second threshold value; 3. The wheel nut loosening detection device according to claim 2, wherein the second control unit is configured to cause the notification unit to notify the user of the remaining battery life when the receiving unit receives the specific signal.

11. The wheel nut loosening detection device according to claim 10 , wherein the first control unit goes into a low power mode when the voltage is higher than a second threshold value, and goes into a normal power mode when the voltage is lower than the second threshold value.

12. 5. A wheel nut loosening detection device according to claim 4, wherein each of said nut rings has an annular portion which is rotatable and adjustable about said axis.

13. 13. A wheel nut loosening detection device according to claim 12, wherein each of the nut rings has an annular portion that is rotatable about the axis only in a direction in which the wheel nut is loosened.

14. The first control device is housed in a case, 3. A wheel nut loosening detection device according to claim 1, wherein said case is held in said housing in a sealed state.

15. the housing includes a base plate that is fixed to the wheel by screwing each of the shaft portions with the wheel nuts; 15. A wheel nut loosening detection device according to claim 14, further comprising a cover plate which is fitted to said base plate with said case sandwiched between said cover plate and said base plate, and which conceals each of said nut rings.

16. 3. The wheel nut loosening detection device according to claim 1, wherein a hexagonal portion of each of the wheel nuts is exposed when the sensor unit is attached.

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