Wheel nut loosening detection system and hub unit bearing equipped with the same

Abstract

To provide a wheel nut loosening detection system capable of accurately and inexpensively detecting wheel nut loosening, and a hub unit bearing equipped with the same.SOLUTION: A wheel nut loosening detection system 10 for detecting loosening of a wheel nut 18 is provided with a detection device 40 including an encoder 41 mounted on a wheel 15 and a sensor 42 mounted on a rotating-side member 30, which detects a rotational signal of the encoder 41 and acquires a rotational phase difference between the rotating-side member and the wheel 15. When a braking force acts on the rotating-side member 30, the system detects whether the wheel nut 18 is loose based on changes in the rotational phase difference between the rotating-side member 30 and the wheel 15 detected by the sensor 42.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wheel nut loosening detection system and a hub unit bearing equipped with the detection system. [Background technology]

[0002] To prevent wheel detachment accidents involving large vehicles, the Ministry of Land, Infrastructure, Transport and Tourism and the Japan Automobile Manufacturers Association recommend installing an indicator that can detect loose wheel nuts on the left rear wheel, which is particularly prone to accidents.

[0003] As shown in Fig. 7, the wheel nut cap described in Patent Document 1 has a dome-shaped cap body 110 made entirely of resin, and a substantially triangular indicator 120 attached to each wheel nut 100. The indicators 120 are attached to the wheel nuts 100 so that the indicators 120 attached to adjacent wheel nuts 100 face each other, or so that all of the indicators 120 face in the same direction, and loosening of the wheel nuts 100 can be detected by visually checking if the orientation of the indicators 120 has changed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-7274 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the wheel nut cap described in Patent Document 1 is inexpensive, it has the following three problems and further improvements are desired. 1. Because there is a limit to the phase in which the indicator 120 can be attached, it is difficult to align the indicators 120 of adjacent wheel nuts 100 so that they face each other perfectly, which reduces the accuracy of detecting loose nuts. 2. There are many attachment points, making installation time-consuming. Also, considering the time and effort involved, it is difficult to attach it to all wheels. 3. It is difficult to apply to the front wheel as there is a risk of it coming off due to air currents.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a wheel nut loosening detection system that can detect looseness of wheel nuts accurately and inexpensively, and a hub unit bearing that is equipped with such a detection system. [Means for solving the problem]

[0007] Therefore, the above object of the present invention is achieved by the following configurations [1] and [2] relating to a wheel nut loosening detection system. [1] A stationary member that does not rotate; a rotating flange having a wheel and a braking rotating member attached to its outer periphery by means of a plurality of bolt members and a plurality of wheel nuts; and a rotating member that rotates integrally with the rotating flange. a rolling bearing provided between the stationary-side member and the rotating-side member, the rolling bearing supporting the rotating-side member rotatably relative to the stationary-side member; a detection device for detecting looseness of the wheel nuts; A wheel nut loosening detection system comprising: The detection device includes an encoder attached to the wheel; a sensor attached to the rotating member to detect a rotation signal from the encoder and obtain a rotation phase difference between the encoder and the wheel; When a braking force is applied to the rotating member, the sensor detects whether the wheel nut is loose or not based on a change in the rotation phase between the rotating member and the wheel. Wheel nut looseness detection system.

[0008] [2] A stationary member that does not rotate; a rotating flange having a wheel and a braking rotating member attached to its outer periphery by means of a plurality of bolt members and a plurality of wheel nuts; and a rotating member that rotates integrally with the rotating flange. a rolling bearing provided between the stationary-side member and the rotating-side member, the rolling bearing supporting the rotating-side member rotatably relative to the stationary-side member; a detection device for detecting looseness of the wheel nuts; A wheel nut loosening detection system comprising: The detection device includes: a pair of encoders attached to the wheel and the rotating member, respectively; a pair of sensors attached to the stationary member for detecting rotation signals of the pair of encoders, when a braking force is applied to the rotating member, the phases of the rotation signals of the pair of encoders are compared, and whether or not the wheel nuts are loose is detected based on a change between the phases of the rotation signals of the pair of encoders. Wheel nut looseness detection system. [Effects of the Invention]

[0009] According to the wheel nut loosening detection system and the hub unit bearing equipped with the detection system of the present invention, looseness of wheel nuts can be detected accurately and inexpensively. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of a tire support structure according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a main part of the tire support structure when the wheel nuts are not loosened. [Figure 3]Figure 3(a) is a side view showing the positional relationship between the bolt member and the wheel when the wheel nut is not loose, Figure 3(b) is a side view showing the positional relationship between the bolt member and the wheel when the wheel nut is loose, and Figure 3(c) is a side view showing the positional relationship between the bolt member and the wheel when a braking force acts on the rotating side member when the wheel nut is loose. [Figure 4] FIG. 4 is a cross-sectional view of a main part of the tire support structure when the wheel nut is loose. [Figure 5] Figure 5 relates to a second embodiment of the present invention, and Figure 5(a) is a cross-sectional view of a main part of the tire support structure when the wheel nuts are not loosened, and Figure 5(b) is a cross-sectional view of a main part of the tire support structure when the wheel nuts are loosened. [Figure 6] FIG. 6 is a cross-sectional view of a main part of a tire support structure according to a third embodiment. [Figure 7] FIG. 7 is a front view of a wheel with a conventional wheel nut cap attached to a wheel nut. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wheel nut loosening detection system and a hub unit bearing including the detection system according to each embodiment of the present invention will be described in detail below with reference to the drawings.

[0012] (First embodiment) 1 and 2 show an example in which a wheel nut loosening detection system 10 of this embodiment is applied to a fully floating rear axle equipped with a first-generation hub unit bearing. In this wheel nut loosening detection system 10, an axle shaft 11 that transmits drive torque from a drive source to a hub (rotating member) 30 is disposed inside an axle case 12 (stationary member) that is supported on the vehicle frame via springs (not shown). A radially extending flange portion 11a is integrally formed at the end of the axle shaft 11. The hub 30 is attached to the outer periphery of the flange portion 11a with bolts 13.

[0013] The hub 30 includes a cylindrical portion 31 and a rotating flange 32 extending radially outward from the cylindrical portion 31. A circular pilot portion 33 is provided in a bulging manner on the portion of the cylindrical portion 31 extending outboard from the rotating flange 32.

[0014] A disc wheel 15 of a dual tire 14 is attached to the rotating flange 32 together with a brake drum (a rotating member for braking) 16 by a plurality of bolt members 17 and a plurality of wheel nuts 18 .

[0015] 3(a), a plurality of (six in the figure) bolt members 17 are implanted at regular intervals in the circumferential direction of the rotating flange 32. The disc wheel 15 is provided with a mounting hole 15a at its center, the mounting hole 15a having an inner diameter larger than the outer diameter of the pilot portion 33, and a plurality of (six in the figure) hub bolt holes 15b corresponding to the plurality of bolt members 17 are provided around the mounting hole 15a.

[0016] The disc wheel 15 is attached to the rotating flange 32 by inserting the pilot portion 33 into the mounting hole 15a, and guiding it with the pilot portion 33, inserting the bolt members 17 into each of the multiple hub bolt holes 15b, and fastening them with wheel nuts 18.

[0017] The hub 30 is rotatably supported relative to the axle case 12 by double-row rolling bearings, i.e., an inboard bearing 21 and an outboard bearing 22, which are spaced apart from each other in the axial direction of the axle shaft 11. This allows the dual tires 14 to be rotatably supported relative to the axle case 12.

[0018] The inboard bearing portion 21 and the outboard bearing portion 22 are tapered roller bearings, and an integral outer ring 24, with outer ring raceways 24a, 24b formed on the inner peripheral surface, is fitted and fixed within the cylindrical portion 31 of the hub 30. The integral outer ring 24 is fitted within the cylindrical portion 31, and with the outboard end abutting against a step portion 34 of the cylindrical portion 31, the inboard end is positioned in the axial direction by a retaining ring 37 that fits into a ring groove 36 formed in the hub 30.

[0019] Furthermore, the inner ring 25 of the inboard-side bearing portion 21 and the inner ring 26 of the outboard-side bearing portion 22 are fitted with a clearance fit to the outer peripheral surface 12a of the axle case 12 with no backlash. Inner ring raceways 25a and 26a are formed on the outer peripheral surfaces of the inner rings 25 and 26, respectively. A plurality of tapered rollers 23, which are rolling elements rotatably held by a cage 27, are rollably loaded between the outer ring raceway 24a and the inner ring raceway 25a, and between the outer ring raceway 24b and the inner ring raceway 26a.

[0020] The inner ring 25 of the inboard side bearing portion 21 is restricted from displacement toward the inside of the vehicle by the step portion 12b of the axle case 12 on the large flange side, and the inner ring 26 of the outboard side bearing portion 22 is fixed to the axle case 12 by the hub nut 19 on its large flange side, with displacement toward the outside of the vehicle restricted.

[0021] Then, by screwing and tightening the hub nut 19 onto the male thread portion 12c formed on the outer surface of the end of the axle case 12, a preload is applied to the inboard side bearing portion 21 and the outboard side bearing portion 22, increasing the rigidity of the bearings and absorbing the gaps that occur between the tapered rollers 23 and the outer ring raceways 24a, 24b and inner ring raceways 25a, 26a.

[0022] In addition, sealing members 20a and 20b prevent the lubricant inside the bearing from leaking out to the outside, and sealing member 20a prevents foreign matter such as dust from the outside from entering the inside of the bearing, while sealing member 20b prevents differential oil inside the axle case 12 from entering the inside of the bearing.

[0023] An encoder 41 is disposed on a member (disc wheel 15 in the illustrated embodiment) that rotates integrally with the dual tires 14. A sensor 42 is also fixed to the axle case 12 with its detection surface facing the detected surface of the encoder 41. The encoder 41 and sensor 42 constitute a detection device 40.

[0024] The encoder 41 is made of a permanent magnet, and the characteristic change portion has N-pole magnetized portions and S-pole magnetized portions arranged alternately and at equal intervals.

[0025] The detection surface of the sensor 42, which is arranged closely opposite the detected surface of the encoder 41, incorporates a magnetic detection element such as a Hall IC, Hall element, MR element, or GMR element, and detects the change in the magnetic force of the encoder 41 when the encoder 41 is displaced relative to the sensor 42, thereby detecting the rotation signal of the encoder 41.

[0026] In the wheel nut loosening detection system configured as described above, when the wheel nut 18 is not loose and the disc wheel 15 is attached to the rotating flange 32 in the correct position, as shown in Figures 2 and 3(a), a substantially constant radial gap C is formed between the outer diameter of the pilot portion 33 and the inner diameter of the attachment hole 15a of the disc wheel 15. In other words, the disc wheel 15 is attached concentrically with the pilot portion 33. Furthermore, each bolt member 17 is positioned approximately at the center of each hub bolt hole 15b of the disc wheel 15. In other words, there is no contact between the pilot portion 33 and the attachment hole 15a, and between the bolt member 17 and the hub bolt hole 15b.

[0027] When the wheel nut 18 is not loose, the sensor 42 outputs a predetermined rotation signal in response to the rotation of the disc wheel 15 and the hub 30, that is, the encoder 41.

[0028] Here, as shown in Figures 3(b) and 4, when the wheel nut 18 loosens, the disc wheel 15 becomes able to move radially, and the mounting hole 15a of the disc wheel 15 comes into contact with the pilot portion 33 in the phase where it comes closer to the road surface (the phase where the load is applied).

[0029] Since the outer diameter of the pilot portion 33 is smaller than the inner diameter of the mounting hole 15a of the disc wheel 15, when the contact between the two becomes strong, a large circumferential friction force is generated in the disc wheel 15, causing the rotational phase of the disc wheel 15 to lag behind the rotational phase of the hub 30.

[0030] When the braking rotating member 16 is braked in this state, as shown in Figure 3(c), a braking force acts on the hub 30, but the disc wheel 15 continues to rotate due to the inertial force of the dual tires 14, etc., and the rotational phase of the disc wheel 15 suddenly advances relative to the rotational phase of the hub 30.

[0031] Therefore, by detecting the rotation signal of the encoder 41 fixed to the disc wheel 15 using a sensor 42 attached to the hub 30 (rotating member) and capturing the sudden change in the rotational phase difference between the hub 30 and the disc wheel 15 at the moment when braking begins (the moment when the brake lamp comes on), it is possible to detect whether the wheel nut 18 is loose or not.

[0032] Although the above embodiment uses a first-generation hub unit bearing, the present invention is not limited to this and may be applied to second- or third-generation hub unit bearings in which the outer ring rotates. The hub unit bearing may also have two single-row rolling bearings.

[0033] (Second embodiment) As shown in FIG. 5( a ), the second embodiment shows an example in which the wheel nut loosening detection system 10 according to the present invention is applied to a front wheel having a single tire (not shown) 14 .

[0034] In the wheel nut loosening detection system 10 of this embodiment, a hub 30 is rotatably supported on the outer diameter side of a stub axle case 12, which is supported using a thrust bearing and a kingpin (both not shown) on an axle beam attached to the vehicle frame (not shown) via a spring, via a second-generation hub unit bearing having an inboard side bearing portion 21 and an outboard side bearing portion 22.

[0035] The inner ring 25 of the inboard side bearing portion 21 and the inner ring 26 of the outboard side bearing portion 22 are provided with inner ring raceways 25a and 26a on their respective outer peripheral surfaces, and are fitted with a clearance fit to the outer peripheral surface 12a of the stub axle case 12 with no play, and their axial position is regulated by the step portion 12b of the stub axle case 12 and the hub nut 19.

[0036] The hub 30 has an outer ring 24 with outer ring raceways 24a, 24b integrally formed on its inner circumferential surface, and a rotating flange 32 at the outboard end of its outer circumferential surface. The disc wheel 15 of the single tire 14, together with the brake drum 16, is attached to the rotating flange 32 by a plurality of bolt members 17 and a plurality of wheel nuts 18.

[0037] An end cover 35 is fitted and fixed to the outboard side inner diameter end of the outer ring 24 of the hub 30 so as to close the outboard side opening of the hub 30. Furthermore, on the inboard side of the inboard side bearing 21, a seal member 20a is attached between the outer ring 24 and the inner ring 25 of the inboard side bearing 21 to prevent the lubricant inside the bearing from leaking out and to prevent foreign matter such as dust from entering the inboard side bearing 21 and the outboard side bearing 22 from the outside.

[0038] An encoder 41 is attached to the outboard end surface of the disc wheel 15. Furthermore, a sensor 42 is fixed with its detection surface facing closely to the detected surface of the encoder 41. The encoder 41 and the sensor 42 constitute a detection device 40.

[0039] In this wheel nut loosening detection system 10, as in the first embodiment, the disc wheel 15 is attached concentrically with the pilot portion 33, and each bolt member 17 is positioned approximately in the center of each hub bolt hole 15b of the disc wheel 15, as shown in FIG. 3(a). When the wheel nut 18 loosens, the mounting hole 15a of the disc wheel 15 comes into contact with the pilot portion 33 when the phase of the wheel nut 18 moves toward the road surface, as shown in FIGS. 3(b) and 5(b). When this contact becomes strong and a large circumferential friction force is generated in the disc wheel 15, the rotational phase of the disc wheel 15 lags behind the rotational phase of the hub 30.

[0040] If the brake is applied to the hub 30 in this state, as shown in Figure 3(c), a braking force acts on the hub 30, but the disc wheel 15 continues to rotate due to the inertial force of the single tire 14, etc., and the rotational phase of the disc wheel 15 suddenly advances relative to the rotational phase of the hub 30.

[0041] Therefore, by using the sensor 42 to detect the rotation signal of the encoder 41 fixed to the disc wheel 15 and capturing the sudden change in rotation phase at the moment when braking begins (the moment when the brake lamp turns on), it is possible to detect whether the wheel nut 18 is loose or not.

[0042] Although the above embodiment uses a second-generation hub unit bearing, the present invention is not limited to this and may also be applied to first- or third-generation hub unit bearings in which the outer ring rotates. The hub unit bearing of this embodiment may also have two single-row rolling bearings.

[0043] (Third embodiment) The wheel nut loosening detection system 10 according to this embodiment includes two sets of detection devices 40A, 40B, and is applied to a front wheel having a single tire (not shown) 14.

[0044] As shown in Figure 6, in the wheel nut loosening detection system 10 of this embodiment, a first encoder 41A is attached to the outboard end face of the disc wheel 15, and a first sensor 42A is attached to the outer peripheral surface 12d provided at the tip of the shaft portion of the stub axle case 12, which is the fixed side member, with its detection surface closely facing the detected surface of the first encoder 41A.

[0045] Furthermore, a second encoder 41B is attached to the inboard end face of the hub 30, which is the rotating member, and a second sensor 42B is attached to the outboard end face of the stub axle case 12, which is also the fixed member, with its detection surface closely facing the detected surface of the second encoder 41B. In other words, the first encoder 41A and the first sensor 42A make up a first detection device 40A, and the second encoder 41B and the second sensor 42B make up a second detection device 40B.

[0046] Then, the first sensor 42A detects the rotation signal of the first encoder 41A, and the second sensor 42B detects the rotation signal of the second encoder 41B. The phases of the rotation signals from the two sensors 42A and 42B are compared at the moment when braking begins (the moment the brake lights come on) to determine the difference between the rotation signals.

[0047] When the wheel nut 18 is tight, the disc wheel 15 and hub 30 rotate together, so the rotation signals detected by both sensors 42A and 42B are the same, and the phase difference between the two rotation signals is zero.

[0048] On the other hand, when the wheel nut 18 is loose, a difference in behavior is observed between the disc wheel 15 and the hub 30, and the moment braking begins, a phase difference occurs between the phases of the rotation signals from both sensors 42A and 42B. Therefore, by detecting a sudden change in the rotation phase difference (a change from lag to lead), it is possible to detect whether the wheel nut 18 is loose.

[0049] Although not shown in the figures, the wheel nut loosening detection system 10, which uses the two detection devices 40A, 40B described above to detect whether the wheel nut 18 is loose or not from the rotational phase difference between the disc wheel 15 and the hub 30, can also be applied to a fully floating rear wheel axle (see Figure 1).

[0050] The present invention is not limited to the above-described embodiment, and modifications and improvements are possible as appropriate.

[0051] As described above, the present specification discloses the following: (1) A stationary member that does not rotate; a rotating flange having a wheel and a braking rotating member attached to its outer periphery by means of a plurality of bolt members and a plurality of wheel nuts; and a rotating member that rotates integrally with the rotating flange. a rolling bearing provided between the stationary-side member and the rotating-side member, the rolling bearing supporting the rotating-side member rotatably relative to the stationary-side member; a detection device for detecting looseness of the wheel nuts; A wheel nut loosening detection system comprising: The detection device includes an encoder attached to the wheel; a sensor attached to the rotating member to detect a rotation signal from the encoder and obtain a rotation phase difference between the encoder and the wheel; When a braking force is applied to the rotating member, the sensor detects whether the wheel nut is loose or not based on a change in the rotation phase between the rotating member and the wheel. Wheel nut looseness detection system. According to this configuration, looseness of the wheel nuts can be detected accurately and inexpensively.

[0052] (2) a stationary member that does not rotate; a rotating flange having a wheel and a braking rotating member attached to its outer periphery by means of a plurality of bolt members and a plurality of wheel nuts; and a rotating member that rotates integrally with the rotating flange. a rolling bearing provided between the stationary-side member and the rotating-side member, the rolling bearing supporting the rotating-side member rotatably relative to the stationary-side member; a detection device for detecting looseness of the wheel nuts; A wheel nut loosening detection system comprising: The detection device includes: a pair of encoders attached to the wheel and the rotating member, respectively; a pair of sensors attached to the stationary member for detecting rotation signals of the pair of encoders, when a braking force is applied to the rotating member, the phases of the rotation signals of the pair of encoders are compared, and whether or not the wheel nuts are loose is detected based on a change between the phases of the rotation signals of the pair of encoders. Wheel nut looseness detection system. According to this configuration, looseness of the wheel nuts can be detected accurately and inexpensively.

[0053] (3) A hub unit bearing equipped with the wheel nut loosening detection system described in (1) or (2). According to this configuration, it is possible to provide a hub unit bearing equipped with a detection system that can detect looseness of wheel nuts with high accuracy and at low cost. [Explanation of symbols]

[0054] 10. Wheel nut looseness detection system 12 Axle case (stationary side component) 15 Disc Wheel (Wheel) 16 Braking rotating member 17 Bolt material 18 Wheel nuts 23 Tapered roller (rolling element) 25, 26 Inner circle 30 Hub (rotating part) 32 Rotating flange 40 Detection Device 40A First detection device (detection device) 40B Second detection device (detection device) 41 Encoder 41A First Encoder (Encoder) 41B Second encoder (encoder) 42 sensors 42A First Sensor (Sensor) 42B Second sensor (sensor)

Claims

1. a stationary member that does not rotate; a rotating flange having a wheel and a braking rotating member attached to its outer periphery by means of a plurality of bolt members and a plurality of wheel nuts; and a rotating member that rotates integrally with the rotating flange. a rolling bearing provided between the stationary-side member and the rotating-side member, the rolling bearing supporting the rotating-side member rotatably relative to the stationary-side member; a detection device for detecting looseness of the wheel nuts; A wheel nut loosening detection system comprising: The detection device includes an encoder attached to the wheel; a sensor attached to the rotating member to detect a rotation signal from the encoder and obtain a rotation phase difference between the encoder and the wheel; When a braking force is applied to the rotating member, the sensor detects whether the wheel nut is loose or not based on a change in the rotation phase between the rotating member and the wheel. Wheel nut looseness detection system.

2. a stationary member that does not rotate; a rotating flange having a wheel and a braking rotating member attached to its outer periphery by means of a plurality of bolt members and a plurality of wheel nuts; and a rotating member that rotates integrally with the rotating flange. a rolling bearing provided between the stationary-side member and the rotating-side member, the rolling bearing supporting the rotating-side member rotatably relative to the stationary-side member; a detection device for detecting looseness of the wheel nuts; A wheel nut loosening detection system comprising: The detection device includes: a pair of encoders attached to the wheel and the rotating member, respectively; a pair of sensors attached to the stationary member for detecting rotation signals of the pair of encoders, when a braking force is applied to the rotating member, the phases of the rotation signals of the pair of encoders are compared, and whether or not the wheel nuts are loose is detected based on a change between the phases of the rotation signals of the pair of encoders. Wheel nut looseness detection system.

3. A hub unit bearing comprising the wheel nut loosening detection system according to claim 1 or 2.

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