Method and device for measuring preload of hub unit bearing

Abstract

To provide a method for measuring a preload of a hub unit bearing, which can suppress a thrust load applied to the hub unit bearing and can also be applied to a tapered roller bearing type hub unit bearing.SOLUTION: In a state of abutting a transmitting probe 22 against one end of an axially outer end and an axially inner end of a hub 3 and abutting a receiving probe 23 against the other end of the axially outer end and the axially inner end of the hub 3, sound waves or vibrations transmitted from the transmitting probe 22 are received by the receiving probe 23 while applying a thrust load to between an outer ring 2 and the hub 3, and the transmission by the transmitting probe 22 and the reception by the receiving probe 23 are repeated while increasing the thrust load continuously or stepwise until a variation is detected in the sound waves or vibrations received by the receiving probe 23.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a preload measuring method and device for a hub unit bearing. [Background technology]

[0002] A hub unit bearing supports the wheels of an automobile for rotation relative to a suspension system. The hub unit bearing includes an outer ring having multiple rows of outer ring raceways on its inner circumferential surface, a hub having multiple rows of inner ring raceways on its outer circumferential surface, and a plurality of rolling elements arranged to roll freely between the multiple rows of outer ring raceways and the multiple rows of inner ring raceways.

[0003] In a hub unit bearing, a preload is applied to the rolling elements to suppress rattling between the outer ring and the hub and to enable smooth relative rotation between the outer ring and the inner ring.

[0004] If the preload applied to the rolling elements is too large, problems such as a shortened lifespan of the hub unit bearing and a deterioration in the running performance of the vehicle due to an increase in the dynamic torque of the hub unit bearing are likely to occur.

[0005] On the other hand, if the preload applied to the rolling elements is too small, the moment rigidity of the hub unit bearing will be insufficient, which can easily cause problems such as a decrease in vehicle handling stability.

[0006] For this reason, the preload in the hub unit bearing must be strictly controlled, and after assembly of the hub unit bearing is complete, it is required to inspect whether an appropriate preload is applied to the rolling elements.

[0007] JP 2021-148710 A discloses a preload measurement method that can calculate the preload applied to the rolling elements after assembly of the hub unit bearing is completed.

[0008] The preload measurement method described in JP 2021-148710 A measures the axial relative distance between the outer ring and the hub while increasing the thrust load that presses the outer ring and the hub from both axial sides. Then, an inflection point on the transition line of the relative distance is identified, and the thrust load at which the inflection point appears is determined. After that, the preload applied to the rolling elements of the hub unit bearing is calculated from the thrust load. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-148710 Summary of the Invention [Problem to be solved by the invention]

[0010] The preload measurement method described in JP 2021-148710 A identifies an inflection point on the transition line of the axial relative distance between the outer ring and the hub, and calculates the preload using the inflection point, so there are two problems as follows:

[0011] First, in a tapered roller hub unit bearing that uses tapered rollers as rolling elements, when a thrust load is applied, the transition line of the axial relative distance between the outer ring and the hub becomes almost linear, making it difficult to identify the inflection point. For this reason, it is difficult to apply the preload measurement method described in JP 2021-148710 A to a tapered roller hub unit bearing.

[0012] In addition, when a thrust load is applied to a ball bearing type hub unit bearing, the change in the inflection point that appears on the transition line of the axial relative distance between the outer ring and the hub is small, so in order to identify the inflection point, it is necessary to apply a thrust load that is sufficiently larger than the thrust load at which the inflection point appears. This increases the number of steps required to calculate the preload. In addition, damage such as scratches and indentations may occur on the raceway surface and rolling surface.

[0013] An object of the present disclosure is to provide a preload measuring method for a hub unit bearing that can reduce the thrust load applied to the hub unit bearing and that can also be applied to a tapered roller bearing type hub unit bearing. [Means for solving the problem]

[0014] A hub unit bearing, which is the subject of a preload measuring method and preload measuring device for a hub unit bearing according to one aspect of the present disclosure, includes an outer ring, a hub, and a plurality of rolling elements.

[0015] The outer ring has a plurality of rows of outer ring raceways on its inner circumferential surface.

[0016] The hub has a plurality of rows of inner ring raceways on its outer circumferential surface.

[0017] The plurality of rolling elements are disposed so as to roll freely between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways.

[0018] The hub has a hub wheel having at least the axially outermost inner ring raceway among the multiple rows of inner ring raceways on its outer peripheral surface, and an inner ring having at least the axially innermost inner ring raceway among the multiple rows of inner ring raceways on its outer peripheral surface.

[0019] A method for measuring a preload on a hub unit bearing according to one aspect of the present disclosure includes a transmitting and receiving process in which a transmitting probe is abutted against one of the axially outer end and the axially inner end of the hub and a receiving probe is abutted against the other of the axially outer end and the axially inner end of the hub, and while applying a thrust load between the outer ring and the hub, sound waves or vibrations transmitted from the transmitting probe are received by the receiving probe, and the transmission and reception by the receiving probe are repeated while continuously or stepwise increasing the thrust load until a fluctuation is detected in the sound waves or vibrations received by the receiving probe.

[0020] A preload measuring method for a hub unit bearing according to one aspect of the present disclosure includes a preload calculation step of calculating the preload based on the thrust load applied between the outer ring and the hub at the time the fluctuation was detected.

[0021] In the method for measuring a preload of a hub unit bearing according to one aspect of the present disclosure, in the transmitting and receiving step, the sound waves or the vibrations transmitted from the transmitting probe are received by an auxiliary receiving probe abutted against the outer ring.

[0022] In the method for measuring a preload of a hub unit bearing according to one aspect of the present disclosure, in the transmitting and receiving step, a change in the number of times the sound waves or vibrations are received by the receiving probe is detected as the fluctuation.

[0023] In the method for measuring a preload of a hub unit bearing according to one aspect of the present disclosure, the transmitting and receiving step is performed while rotating the outer ring and the hub relative to each other.

[0024] A preload measuring device for a hub unit bearing according to one aspect of the present disclosure includes a load application device, a load measuring device, a transmitting probe, a receiving probe, and a computing unit.

[0025] The load applying device applies a thrust load to the hub unit bearing.

[0026] The load measuring device measures the thrust load pressing the outer ring and the hub from both axial sides.

[0027] The transmitting probe is connected to a transmitter capable of transmitting sound waves or vibrations, and is in contact with one of the axially outer end and axially inner end of the hub.

[0028] The receiving probe is connected to a receiver capable of receiving the sound waves or the vibrations and to the computing unit, and is in contact with the other of the axially outer end and the axially inner end of the hub.

[0029] The calculator has a function of detecting fluctuations in the sound waves or vibrations received by the receiving probe, and a function of calculating the preload based on the thrust load applied to the outer ring and the hub at the time the fluctuations were detected. Effect of the Invention

[0030] According to the method for measuring the preload of a hub unit bearing according to one aspect of the present disclosure, the thrust load applied to the hub unit bearing can be reduced, and the method can also be applied to a tapered roller bearing type hub unit bearing. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a cross-sectional view showing a hub unit bearing according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view showing a state in which the first example of the method for measuring preload of a hub unit bearing is carried out. [Diagram 3] FIG. 3 is a diagram corresponding to FIG. 2 and relating to a second example of the embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram corresponding to FIG. 2 and relating to a third example of an embodiment of the present disclosure. [Diagram 5] FIG. 5 is a diagram corresponding to FIG. 2 and relating to a fourth embodiment of the present disclosure. [Figure 6] 6A to 6C are half cross-sectional views showing two examples of the implementation of a preload measuring method for a hub unit bearing according to a fifth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] [Example 1] A first example of an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2. FIG.

[0033] <Hub unit bearing structure> FIG. 1 shows a hub unit bearing 1 which is the subject of a preload measuring method for a hub unit bearing according to one embodiment of the present invention.

[0034] The hub unit bearing 1 includes an outer ring 2, a hub 3, and a plurality of rolling elements 4a, 4b.

[0035] With regard to the hub unit bearing 1, the left side in FIG. 1 and the upper side in FIG. 2, which are located on the outer side in the width direction of the vehicle when the hub unit bearing 1 is assembled to the vehicle, are referred to as the axial outer side, and the right side in FIG. 1 and the lower side in FIG. 2, which are located on the central side in the width direction of the vehicle when the hub unit bearing 1 is assembled to the vehicle, are referred to as the axial inner side.

[0036] The outer ring 2 has a substantially cylindrical shape and has a plurality of rows of outer ring raceways 5a, 5b on its inner circumferential surface.

[0037] In this example, the outer ring 2 has double-row outer ring raceways 5a, 5b on its inner circumferential surface. That is, the outer ring 2 has two rows of outer ring raceways 5a, 5b.

[0038] The double row outer ring raceways 5a, 5b have an arc-shaped cross section in a cross section including the center axis of the outer ring 2.

[0039] The outer ring 2 has a stationary flange 6 protruding radially outward at an axially intermediate portion. The stationary flange 6 has support holes 7 penetrating in the axial direction at a plurality of circumferential positions at the radially intermediate portion.

[0040] In this example, the support hole 7 is configured as a screw hole. The outer ring 2 is supported and fixed to the suspension by a support bolt that is inserted through a through hole provided in the knuckle of the suspension and is screwed into the support hole 7 of the stationary flange 6 from the inside in the axial direction, so that the outer ring 2 does not rotate even when the wheel rotates.

[0041] The support hole may be a circular hole. In this case, the outer ring is supported and fixed to the knuckle by screwing a support bolt inserted through the support hole into a threaded hole provided in the knuckle, or by screwing a nut onto a tip of a support bolt inserted through the support hole and a through hole provided in the knuckle.

[0042] The outer ring 2 is made of a hard metal such as medium carbon steel.

[0043] The hub 3 is disposed radially inside the outer ring 2 and coaxially with the outer ring 2. The hub 3 has a plurality of rows of inner ring raceways 8a, 8b on its outer circumferential surface.

[0044] In this example, the hub 3 has double row inner ring raceways 8a, 8b on its outer circumferential surface. That is, the hub 3 has two rows of inner ring raceways 8a, 8b.

[0045] The double row inner ring raceways 8a, 8b have an arc-shaped cross section in a cross section including the central axis of the hub 3.

[0046] The double row inner ring raceways 8a, 8b are provided over the entire circumference of the outer circumferential surface of the hub 3 in portions that face the double row outer ring raceways 5a, 5b.

[0047] The hub 3 has a rotation flange 9 protruding radially outward at a portion that protrudes axially outward beyond the outer ring 2. The hub 3 has a cylindrical pilot portion 10 at the end on the axially outer side.

[0048] The rotating flange 9 has mounting holes 11 penetrating in the axial direction at multiple circumferential positions in a radially middle portion. Studs 12 for connecting and fixing a braking rotor such as a disc or drum and a wheel that constitutes a wheel to the rotating flange 9 are press-fitted into each of the mounting holes 11 with serrations. That is, in this example, the mounting holes 11 are cylindrical holes.

[0049] A braking rotating body such as a brake disc and a wheel of a vehicle are connected and fixed to the rotating flange 9 by inserting a pilot portion 10 into a central hole provided in the center of each of them and inserting a stud 12 into through holes provided at multiple locations in the circumferential direction of each of them in the radial middle portion, and then screwing a hub nut onto the tip of the stud 12.

[0050] The mounting hole 11 of the rotating flange 9 can also be configured as a screw hole. In this case, the braking rotor and the wheel are connected and fixed to the rotating flange 9 by screwing a hub bolt, which has passed through a through hole provided in the braking rotor and a through hole provided in the wheel, into the mounting hole 11 from the outside in the axial direction.

[0051] Since the hub unit bearing 1 of this example is a hub unit bearing for a driven wheel, the hub 3 is solid. However, the preload measuring method for a hub unit bearing according to one embodiment of the present disclosure can also be applied to a hub unit bearing for a driving wheel. In this case, the target hub unit bearing has a spline hole penetrating in the axial direction at the center of the hub. A tip end of a drive shaft that is rotationally driven by an engine or an electric motor as a drive source is spline-engaged with the spline hole. When the automobile is traveling, the hub is rotationally driven by the drive shaft, which rotationally drives the wheel and the braking rotor that are coupled and fixed to the rotation flange of the hub.

[0052] The hub 3 is formed by combining an inner ring 13 and a hub ring 14 .

[0053] The inner ring 13 has an annular shape, and has at least the axially innermost inner ring raceway 8b among the multiple rows of inner ring raceways 8a, 8b on its outer circumferential surface.

[0054] In this example, the inner ring 13 has, at an axially inner middle portion of its outer circumferential surface, the inner ring raceway 8b, which is one of the double row inner ring raceways 8a, 8b.

[0055] The inner ring 13 is made of a hard metal such as bearing steel.

[0056] The hub ring 14 has, on its outer circumferential surface, at least the inner ring raceway 8a which is the axially outermost one of the multiple rows of inner ring raceways 8a, 8b.

[0057] In this example, the hub wheel 14 has, in the axially outermost portion of the outer circumferential surface, the inner ring raceway 8a, of the double row inner ring raceways 8a, 8b.

[0058] The hub wheel 14 has a rotating flange 9 that protrudes radially outward at a portion located axially outer than the axially outer inner ring raceway 8a, and has a cylindrical pilot portion 10 at its axially outer end.

[0059] The hub ring 14 has a small diameter step 15, located axially more inward than the axially outer inner ring raceway 8a, which has an outer diameter smaller than that of an adjacent axially outer portion. The hub ring 14 has a step surface 16 facing axially inward at the axially outer end of the small diameter step 15, and has a crimped portion 17 bent radially outward from the axially inner end of the small diameter step 15.

[0060] The hub ring 14 is made of a hard metal such as medium carbon steel.

[0061] The inner ring 13 is fitted onto the small diameter step 15 of the hub ring 14, and is sandwiched from both axial sides between a step surface 16 and a crimped portion 17 of the hub ring 14. In this way, the inner ring 13 and the hub ring 14 are joined to form the hub 3, and a preload is applied to the rolling elements 4a, 4b.

[0062] In addition, the inner ring can also be clamped from both axial sides between the step surface of the hub wheel and the nut by screwing a nut onto the axially inner end of the hub wheel that protrudes from the axially inner end of the inner ring.

[0063] The rolling elements 4a, 4b are disposed between a plurality of rows of outer ring raceways 5a, 5b and a plurality of rows of inner ring raceways 8a, 8b so as to be rollable in each row, and a preload is applied thereto.

[0064] In this example, the rolling elements 4a and 4b are formed of balls.

[0065] Half the diameter of the rolling elements 4a, 4b is slightly smaller than the respective radii of curvature of the outer ring raceways 5a, 5b and the inner ring raceways 8a, 8b.

[0066] The rolling elements 4a, 4b are made of an iron alloy such as bearing steel or ceramics.

[0067] The rolling elements 4a, 4b are arranged at equal intervals in the circumferential direction by using ring-shaped cages 18a, 18b.

[0068] The hub unit bearing 1 has an equal diameter PCD type structure in which the pitch circle diameter of the rolling elements 4a in the axially outer row is equal to the pitch circle diameter of the rolling elements 4b in the axially inner row. However, the preload measurement method for a hub unit bearing according to one embodiment of the present disclosure can also be applied to a different diameter PCD type hub unit bearing in which the pitch circle diameter of the rolling elements in the axially outer row is larger or smaller than the pitch circle diameter of the rolling elements in the axially inner row.

[0069] <Hub unit bearing preload measuring device>

[0070] An example of a preload measuring device 19 capable of implementing the preload measuring method of the present disclosure will be described with reference to FIG.

[0071] The preload measuring device 19 includes a load applying device 20, a load measuring device 21, a transmitting probe 22, a receiving probe 23, and a computing unit 24.

[0072] With respect to the preload measuring device 19, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction of the hub unit bearing 1 attached to the preload measuring device 19, unless otherwise specified.

[0073] The load applying device 20 applies a thrust load to the hub unit bearing 1 .

[0074] In this example, the load applying device 20 axially presses the hub 3. Specifically, the load applying device 20 presses the rotation flange 9 of the hub 3 axially inward.

[0075] The load applying device 20 has a hub support jig 25 and a load applying device main body (not shown).

[0076] The hub support jig 25 has a hollow disk shape. The hub support jig 25 has an insertion hole 26 in the center, into which the pilot portion 10 of the hub 3 can be inserted without rattle. The hub support jig 25 has a plurality of through holes 27, which are cylindrical holes, around the insertion hole 26. The through holes 27 have the same pitch circle diameter as the mounting holes 11 of the rotating flange 9, and are arranged at the same pitch as the mounting holes 11.

[0077] The hub support jig 25 is tightly fixed to the hub 3 by inserting the same number of studs 12 into the multiple through holes 27. That is, the hub support jig 25 is tightly fixed to the hub 3 by inserting the pilot portion 10 into the insertion hole 26, and inserting the stud 12 that has passed through the mounting hole 11 of the rotating flange 9 into the through hole 27 with the axially inner surface of the hub support jig 25 in surface contact with the axially outer surface of the rotating flange 9. Note that if the mounting hole 11 of the rotating flange 9 is configured as a female threaded hole, the through hole 27 is not necessary.

[0078] The load applying device main body presses the rotation flange 9 of the hub 3 axially inward via the hub support jig 25. The load applying device main body is capable of adjusting the magnitude of the force pressing the hub 3 and the rate at which the force increases.

[0079] The load application device main body can be composed of, for example, a servo motor and a ball screw device, or a hydraulic actuator.

[0080] The load measuring device 21 supports the outer ring 2 on a surface plate 29 and measures the thrust load applied between the outer ring 2 and the hub 3 .

[0081] In this example, the load measuring device 21 measures a thrust load (pressing load) that presses the outer ring 2 and the hub 3 from both sides in the axial direction.

[0082] The load measuring device 21 includes an outer ring support jig 30 and a measuring device main body (not shown).

[0083] The outer ring support jig 30 is supported and fixed to the axially outer surface of the surface plate 29, and supports and fixes the outer ring 2. The outer ring support jig 30 has an insertion hole 31 coaxial with the insertion hole 26 of the hub support jig 25.

[0084] The outer ring support jig 30 is fixed in intimate contact with the outer ring 2 with the axially outer surface of the outer ring support jig 30 in surface contact with the axially inner surface of the stationary flange 6 .

[0085] The measuring device main body measures the thrust load applied between the outer ring 2 and the hub 3, that is, the thrust load pressing the outer ring 2 and the hub 3 from both sides in the axial direction.

[0086] The measuring device main body includes, for example, a plurality of load cells or a six-component force meter (not shown). The measuring device main body is connected to a calculator 24 by a harness (not shown), and sends the measurement result of the thrust load to the calculator 24.

[0087] However, the preload measuring device used to implement the preload measuring method of the present disclosure can also be configured to use a load application device to press the outer ring axially outward, and a load measuring device supporting the hub to measure the thrust load pressing the outer ring and hub from both axial sides.

[0088] The transmitting probe 22 is connected to a transmitter (not shown). The transmitter can transmit sound waves or vibrations via the transmitting probe 22. The transmitting probe 22 abuts against one of the axially outer end and the axially inner end of the hub 3. The transmitting probe 22 is connected to a computing unit 24 by a first harness (not shown).

[0089] In this example, the transmitter can emit a sound wave. Specifically, the transmitter can emit a single pulse sound wave based on a command signal from the calculator 24. However, the transmitter can also be configured to emit a pulse wave or a continuous wave having a time width.

[0090] In this example, the transmitting probe 22 abuts against the axially outer end of the hub 3. Specifically, the transmitting probe 22 abuts against the center of a concave curved surface located radially inside the pilot portion 10 on the axially outer end face of the hub wheel 14.

[0091] The receiving probe 23 is connected to a receiver (not shown). The receiver is capable of receiving sound waves or vibrations via the receiving probe 23. The receiving probe 23 abuts against the other of the axially outer end and the axially inner end of the hub 3. The receiver is connected to the calculator 24 by a second harness (not shown).

[0092] In this example, the receiver is capable of receiving sound waves. The receiver transmits a received signal of the sound waves to the calculator 24 through the second harness.

[0093] The receiving probe 23 abuts against the axially inner end of the hub 3. Specifically, the receiving probe 23 abuts against the center of a conical concave surface located radially inside the crimped portion 17 on the axially inner end face of the hub wheel 14. The transmitting probe 22 and the receiving probe 23 are coaxially arranged on the central axis of the hub 3.

[0094] The transmitter may be a dielectric capable of transmitting vibrations, such as a piezoelectric element, quartz, or tourmaline, and the receiver may be a dielectric capable of receiving vibrations. The transmitting probe may be abutted against the axially inner end of the hub, and the receiving probe may be abutted against the axially outer end of the hub.

[0095] The calculator 24 has a function of analyzing the sound waves or vibrations sent from the receiver through the second harness and detecting fluctuations in the sound waves or vibrations.

[0096] The calculator 24 has the function of calculating the preload applied to the rolling elements 4a, 4b based on the thrust load applied between the outer ring 2 and the hub 3 at the time a fluctuation in the sound waves or vibrations was detected.

[0097] In this example, the calculator 24 has a function of analyzing sound waves and detecting fluctuations in the sound waves. Specifically, the calculator 24 has a function of detecting, as a fluctuation in the sound waves, a change in the number of sound waves received by the receiving probe 23 (receiver) relative to one sound wave transmitted by the transmitting probe 22 (transmitter). However, the calculator may be configured to detect, as a fluctuation in the sound waves or vibrations, a change in the waveform (change in amplitude, change in frequency) of the sound waves or vibrations received by the receiving probe.

[0098] In this example, the calculator 24 has a function of calculating the preload applied to the rolling elements 4a, 4b based on the thrust load applied between the outer ring 2 and the hub 3 at the time when a fluctuation in the sound waves is detected. Specifically, the calculator 24 has a function of calculating the preload applied to the rolling elements 4a, 4b from the thrust load applied between the outer ring 2 and the hub 3 at the time when a change in the number of sound waves received by the receiving probe 23 is detected.

[0099] <How to measure preload on hub unit bearings> We will now explain a preload measurement method for measuring the preload applied to the rolling elements 4a, 4b of the hub unit bearing 1. The preload measurement method (preload measurement process) can be carried out by being incorporated into the assembly process of the hub unit bearing 1, or can be carried out independently of the assembly process.

[0100] The preload measurement method disclosed herein measures the preload applied to the rolling elements 4a, 4b by utilizing the fact that the transmission speed of sound waves or vibrations passing through the inside of the hub unit bearing 1 differs depending on the route the sound waves or vibrations take, and that the route the sound waves or vibrations take changes depending on the magnitude of the thrust load applied between the outer ring 2 and the hub 3.

[0101] The principle of preload measurement using the preload measurement method of the present disclosure will be described.

[0102] When a thrust load, that is, a compression load, is applied between the outer ring 2 and the hub 3, the hub 3 moves axially inward and the distance between the outer ring 2 and hub 3 decreases, so that a preload load F1 greater than the preload F0 applied when the hub unit bearing 1 was assembled is applied to the rolling elements 4a in the axially outer row, whereas a preload load F2 smaller than the preload F0 applied when the hub unit bearing 1 was assembled is applied to the rolling elements 4b in the axially inner row, because the distance between the outer ring 2 and the inner ring 13 (hub 3) increases.

[0103] When the thrust load applied between the outer ring 2 and the hub 3 is increased and reaches a predetermined value Fai, the preload F2 applied to the rolling elements 4b in the axially inner row becomes zero. In other words, the rolling elements 4b in the axially inner row are no longer in contact with the outer ring raceway 5b or the inner ring raceway 8b.

[0104] On the other hand, the speed at which sound waves or vibrations transmitted from the transmitting probe 22 abutted against one of the axially outer end and the axially inner end of the hub 3 reach the receiving probe 23 abutted against the other of the axially outer end and the axially inner end of the hub 3 differs between when the sound waves or vibrations reach the receiving probe 23 by passing only inside the hub wheel 14 and when they reach the receiving probe 23 via the rolling elements 4a, 4b and the outer ring 2. Specifically, the transmission speed of the sound waves or vibrations is slower when they reach the receiving probe 23 by passing through the rolling elements 4a, 4b and the outer ring 2 than when they reach the receiving probe 23 by passing only inside the hub wheel 14.

[0105] Therefore, when the thrust load applied between the outer ring 2 and hub 3 is less than the predetermined value Fai, when a single pulse-like sound wave or vibration is transmitted from the transmitting probe 22, the receiving probe 23 receives the sound wave or vibration twice. In other words, the receiving probe 23 receives the sound wave or vibration that has passed only through the inside of the hub wheel 14, and then receives the sound wave or vibration that has passed through the rolling elements 4a, 4b and the outer ring 2.

[0106] In contrast, when the thrust load applied between the outer ring 2 and hub 3 reaches the predetermined value Fai, the rolling elements 4b in the axially inner row are not in contact with the outer ring raceway 5b or the inner ring raceway 8b, so the sound waves or vibrations transmitted from the transmitting probe 22 pass only through the inside of the hub ring 14 without passing through the rolling elements 4a, 4b and the outer ring 2. For this reason, the receiving probe 23 receives the sound waves or vibrations only once.

[0107] Therefore, the predetermined value Fai can be obtained by detecting the fluctuation of the sound waves or vibrations received by the receiving probe 23. Specifically, the predetermined value Fai can be obtained by detecting the change in the number of sound waves or vibrations received by the receiving probe 23.

[0108] The sound transmission speed in steel is about 5900 m / s for longitudinal waves and about 3200 m / s for transverse waves, and there is a speed difference between longitudinal waves and transverse waves. For this reason, the calculator 24 can count the longitudinal waves and transverse waves received by the receiving probe 23 as separate sounds. In this case, when the thrust load applied between the outer ring 2 and the hub 3 is less than the predetermined value Fai, the receiving probe 23 receives the sound wave or vibration four times, and when the thrust load applied between the outer ring 2 and the hub 3 reaches the predetermined value Fai, the receiving probe 23 receives the sound wave or vibration two times. In order to reliably receive the transverse waves by the receiving probe 23, it is preferable that the contact surfaces of the transmitting probe 22 and the receiving probe 23 are conical or concave.

[0109] When the transmitting probe 22 transmits a sound wave or vibration that is a pulse wave or continuous wave having a time width, if the thrust load applied between the outer ring 2 and the hub 3 is less than the predetermined value Fai, overlapping of waves with the same waveform but different phases occurs. Therefore, the sound wave or vibration received by the receiving probe 23 is a composite wave of the sound wave or vibration that has passed only inside the hub wheel 14 and the sound wave or vibration that has passed through the rolling elements 4a, 4b and the outer ring 2, and the waveform is distorted. In contrast, when the thrust load applied between the outer ring 2 and the hub 3 reaches the predetermined value Fai, the sound wave or vibration received by the receiving probe 23 has a reduced amplitude but is similar in shape to the waveform of the sound wave or vibration transmitted by the transmitting probe 22. Therefore, the predetermined value Fai can be obtained by detecting the fluctuation in the waveform of the sound wave or vibration received by the receiving probe 23. Specifically, the predetermined value Fai can be obtained by detecting that the sound waves or vibrations received by the receiving probe 23 and the sound waves or vibrations transmitted by the transmitting probe 22 have become similar in shape. The fact that the sound waves or vibrations received by the receiving probe 23 and the sound waves or vibrations transmitted by the transmitting probe 22 have become similar in shape is determined by the calculator 24.

[0110] Regarding the hub unit bearing 1, a predetermined relational expression is established between the magnitude of the preload F0 applied to the rolling elements 4a, 4b and the predetermined value Fai according to the Hertz theory, depending on the type of the rolling elements 4a, 4b.

[0111] Specifically, as described in JP 2021-148710 A, when the rolling elements 4a and 4b are balls, the magnitude of the preload F0 and the predetermined value Fai satisfy the following formula 1. When the rolling elements 4a and 4b are tapered rollers, the magnitude of the preload F0 and the predetermined value Fai satisfy the following formula 2. Formula 1: F0=Fai / 2√2 Formula 2: F0 = Fai / 2.2

[0112] Therefore, by detecting the fluctuation of the sound waves or vibrations received by the receiving probe 23 and determining the predetermined value Fai, it is possible to determine the preload F0 applied to the rolling elements 4a, 4b of the hub unit bearing 1. The preload measuring method of the present disclosure utilizes the above-mentioned principle.

[0113] Next, the preload measuring method of this embodiment will be specifically described. The preload measuring method of this embodiment includes a transmission / reception step S1 and a preload calculation step S2. Hereinafter, a case where the preload measuring method is carried out using the preload measuring device 19 will be described.

[0114] (Transmission and reception process S1) In the transmitting and receiving process S1, the transmitting probe 22 is abutted against one of the axially outer end and axially inner end of the hub 3, and the receiving probe 23 is abutted against the other of the axially outer end and axially inner end of the hub 3. While a thrust load is applied between the outer ring 2 and the hub 3, sound waves or vibrations transmitted from the transmitting probe 22 are received by the receiving probe 23. The thrust load is increased and transmission by the transmitting probe 22 and reception by the receiving probe 23 are repeated until a fluctuation is detected in the sound waves or vibrations received by the receiving probe 23.

[0115] For this purpose, the hub unit bearing 1 to be measured is mounted between the load application device 20 and the load measuring device 21 of the preload measuring device 19. Then, in this example, a transmitting probe 22 capable of emitting a single pulse-like sound wave is brought into contact with the end portion on the outer side in the axial direction of the hub 3, and a receiving probe 23 capable of receiving the sound wave is brought into contact with the end portion on the inner side in the axial direction of the hub 3.

[0116] Thereafter, the load applying device 20 presses the rotating flange 9 of the hub 3 axially inward, and an initial thrust load (pressing load) is applied between the outer ring 2 and the hub 3. The initial thrust load is set to a value sufficiently smaller than the predicted value of the predetermined value Fai. The pressing force by the load applying device 20 is increased at a predetermined speed, and the thrust load applied between the outer ring 2 and the hub 3 is continuously increased.

[0117] The magnitude of the initial thrust load is not particularly limited, but may be, for example, 0.2 kN to 1 kN, and preferably 0.4 kN to 0.6 kN. The rate of increase in the pressing force by the load application device 20 is not particularly limited, but may be, for example, 0.1 kN / s to 1 kN / s, and preferably 0.3 kN / s to 0.5 kN / s.

[0118] When the thrust load measured by the load measuring device 21 reaches the initial thrust load, a single pulse-like sound wave is emitted from the transmitting probe 22 based on a command signal from the computing device 24. The sound wave emitted from the transmitting probe 22 passes through the inside of the hub unit bearing 1 and is received by the receiving probe 23.

[0119] The calculator 24 analyzes the sound waves received by the receiving probe 23. Specifically, the calculator 24 counts the number of times the sound waves are received by the receiving probe 23, and stores the number of times the sound waves are received. More specifically, the calculator 24 stores that the receiving probe 23 has received two sound waves (four times if longitudinal waves and transverse waves are counted as separate sounds).

[0120] Next, after a predetermined time has elapsed since the previous transmission of sound waves by the transmitting probe 22, the transmitting probe 22 transmits sound waves again based on a command signal from the calculator 24. The calculator 24 then counts the number of sound waves received by the receiving probe 23 and detects a change in the number of sound waves received by the receiving probe 23. Specifically, it determines whether the number of sound waves received by the receiving probe 23 has changed from two to one (from four to two or three when longitudinal waves and transverse waves are counted as separate sounds).

[0121] The transmission interval (s) of the sound waves from the transmitting probe 22 is not particularly limited, but can be, for example, 0.3 s or more and 1 s or less, and preferably 0.4 s or more and 0.6 s or less.

[0122] Then, the thrust load applied between the outer ring 2 and the hub 3 is continuously increased while the transmitting probe 22 repeats transmission and the receiving probe 23 repeats reception until the calculator 24 detects a change in the number of sound waves received by the receiving probe 23.

[0123] When the thrust load applied to the outer ring 2 and the hub 3 approaches the predetermined value Fai, only the transverse waves of the sound waves transmitted from the transmitting probe 22 become difficult to transmit via the route via the rolling elements 4a, 4b and the outer ring 2. In other words, when the thrust load applied between the outer ring 2 and the hub 3 approaches the predetermined value Fai, the contact surface pressure between the rolling elements 4b in the axially inner row and the outer ring raceway 5b and the inner ring raceway 8b decreases, and relative slippage between the rolling elements 4b and the outer ring raceway 5b and the inner ring raceway 8b is likely to occur, so that the transverse waves vibrating in the relative slip direction become difficult to transmit. On the other hand, since the longitudinal waves vibrate in a direction perpendicular to the outer ring raceway 5b and the inner ring raceway 8b, they do not become difficult to transmit even if the contact surface pressure between the rolling elements 4b and the outer ring raceway 5b and the inner ring raceway 8b decreases. Therefore, in the case where the calculator 24 counts longitudinal waves and transverse waves as separate sounds, when the thrust load applied between the outer ring 2 and the hub 3 approaches the predetermined value Fai, the receiving probe 23 determines that it has received two longitudinal waves and one transverse wave. For this reason, it is possible to use the change in the number of sound waves received by the receiving probe 23 from four to three as a trigger to perform correction processing to accurately determine the predetermined value Fai, such as slowing down the rate at which the pressing force is increased by the load application device 20 or shortening the transmission interval by the transmitting probe 22.

[0124] When the calculator 24 detects that the number of sound waves received by the receiving probe 23 has changed from two to one (four or from three to two if the longitudinal waves and transverse waves are counted as separate sounds), it stores the thrust load applied between the outer ring 2 and the hub 3 at the time the change in the number of sound waves was detected as the predetermined value Fai.

[0125] When implementing the present disclosure, it is also possible to repeat transmission by the transmitting probe 22 and reception by the receiving probe 23 while gradually increasing the thrust load applied between the outer ring 2 and the hub 3 until the calculator 24 detects a change in the number of sound waves received by the receiving probe 23.

[0126] Specifically, first, with an initial thrust load applied between the outer ring 2 and the hub 3 by the load application device 20, sound waves are transmitted from the transmitting probe 22 based on a command from the computing device 24. The sound waves that have passed through the inside of the hub unit bearing 1 are received by the receiving probe 23 and analyzed by the computing device 24. Specifically, the computing device 24 counts the number of sound waves received by the receiving probe 23 and stores the number of times the sound waves have been received. More specifically, the computing device 24 stores that the receiving probe 23 has received sound waves two times (four times if longitudinal waves and transverse waves are counted as separate sounds).

[0127] Next, the load applied between the outer ring 2 and the hub 3 is increased by a predetermined amount by the load application device 20. After that, sound waves are transmitted from the transmitting probe 22 based on a command from the computing device 24. The sound waves that have passed through the inside of the hub unit bearing 1 are received by the receiving probe 23 and analyzed by the computing device 24, the number of sound waves received by the receiving probe 23 is counted, and a change in the number of sound waves received by the receiving probe 23 is detected. Specifically, the computing device 24 determines whether the number of sound waves received by the receiving probe 23 has changed from two to one (from four to two or three when longitudinal waves and transverse waves are counted as separate sounds).

[0128] When the calculator 24 detects a change in the number of sound waves received by the receiving probe 23, the load applied between the outer ring 2 and the hub 3 at that point in time is stored as the predetermined value Fai.

[0129] If the calculator 24 detects no change in the number of sound waves received by the receiving probe 23, the load application device 20 increases the load applied between the outer ring 2 and the hub 3 by the specified amount, and then repeats the process of transmission by the transmitting probe 22 and reception by the receiving probe 23 until a change is detected in the number of sound waves received by the receiving probe 23.

[0130] The increase in the load applied by the load application device 20 is not particularly limited, but may be, for example, from 0.1 kN to 0.5 kN, and preferably from 0.2 kN to 0.4 kN.

[0131] (Preload calculation process S2) The calculator 24 calculates the preload F0 applied to the rolling elements 4a, 4b based on the predetermined value Fai obtained in the transmitting and receiving step S1. Specifically, when the rolling elements 4a, 4b are balls, the calculator 24 calculates the preload F0 by substituting the predetermined value Fai obtained in the transmitting and receiving step S1 into the formula 1.

[0132] In this example, the calculator 24 may be provided with a pass / fail determination function for determining whether or not the calculated preload F0 falls within an allowable range.

[0133] In this example, the calculator 24 may be provided with a function for outputting the calculated preload F0 and / or a function for outputting a pass / fail result.

[0134] The method of measuring the preload of the hub unit bearing 1 of this embodiment can reduce the thrust load applied to the hub unit bearing 1, and can also be applied to tapered roller type hub unit bearings.

[0135] The preload measuring method for the hub unit bearing 1 in this example includes a transmitting and receiving process S1 in which a transmitting probe 22 is abutted against one of the axially outer end and axially inner end of the hub 3, and a receiving probe 23 is abutted against the other of the axially outer end and axially inner end of the hub 3, and sound waves or vibrations transmitted from the transmitting probe 22 are received by the receiving probe 23 while a thrust load is applied between the outer ring 2 and the hub 3, and transmission by the transmitting probe 22 and reception by the receiving probe 23 are repeated while continuously increasing the thrust load until a fluctuation is detected in the sound waves or vibrations received by the receiving probe 23.

[0136] The sound waves or vibrations received by the receiving probe 23 fluctuate when the thrust load applied between the outer ring 2 and the hub 3 reaches the predetermined value Fai. Therefore, according to the preload measuring method for the hub unit bearing 1 of this example, it is not necessary to apply a thrust load that greatly exceeds the predetermined value Fai to the outer ring 2 and the hub 3, so the thrust load applied to the hub unit bearing 1 can be suppressed. Therefore, the number of steps required to calculate the preload can be reduced. In addition, damage such as scratches and indentations can be suppressed from occurring to the rolling elements 4a, 4b, the outer ring raceways 5a, 5b, and the inner ring raceways 8a, 8b.

[0137] The preload measurement method for the hub unit bearing 1 in this example does not use the inflection point on the transition line of the axial relative distance between the outer ring and hub as in the conventional preload measurement method described in JP 2021-148710 A, but uses sound waves or vibrations.Therefore, it can be implemented not only on a ball bearing type hub unit bearing 1 that uses balls as rolling elements, but also on a tapered roller bearing type hub unit bearing 1a (see Figure 4) that uses tapered rollers as rolling elements.

[0138] If the calculator 24 is configured to count longitudinal waves and transverse waves as separate sounds, when the thrust load applied to the outer ring 2 and the hub 3 is continuously increased and the thrust load approaches the predetermined value Fai, a correction process can be performed, such as slowing down the increase rate of the pressing force by the load application device 20 or shortening the transmission interval by the transmission probe 22. Alternatively, when the thrust load applied between the outer ring 2 and the hub 3 is increased stepwise and the thrust load approaches the predetermined value Fai, a correction process can be performed, such as reducing the increase in the thrust load. In either case, the predetermined value Fai can be obtained with high accuracy. Therefore, the load applied to the outer ring 2 and the hub 3 can be suppressed, and the preload F0 can be obtained with high accuracy.

[0139] [Example 2] A second embodiment of the present disclosure will be described with reference to FIG.

[0140] In the preload measuring method for the hub unit bearing 1 of this embodiment, the sound waves or vibrations transmitted by the transmitting probe 22 are received by the auxiliary receiving probe 36 in contact with the outer ring 2 in the transmitting and receiving step S1.

[0141] The preload measuring device 19a used in this example includes a load applying device 20, a load measuring device 21, a transmitting probe 22, a receiving probe 23, a calculator 24, and an auxiliary receiving probe .

[0142] The auxiliary receiving probe 36 is connected to an auxiliary receiver (not shown). The auxiliary receiver is capable of receiving sound waves or vibrations via the auxiliary receiving probe 36. The auxiliary receiving probe 36 abuts against an axially inner portion of the outer ring 2. The auxiliary receiver is connected to the calculator 24 by a third harness (not shown).

[0143] In this example, the auxiliary receiver is capable of receiving sound waves. The auxiliary receiver transmits a received signal of the sound waves to the calculator 24 through the third harness.

[0144] The auxiliary receiving probe 36 abuts against the axially inner end face of the outer ring 2. However, as shown by the dashed line in Figure 3, the auxiliary receiving probe 36 can also abut against the axially inner face of the stationary flange 6 of the outer ring 2.

[0145] In the preload measuring method of this embodiment, in the transmission and reception step S1, the calculator 24 counts the longitudinal waves and transverse waves of the sound waves received by the receiving probe 23 and the auxiliary receiving probe 36, respectively, as separate sounds.

[0146] When the thrust load applied between the outer ring 2 and the hub 3 approaches the predetermined value Fai, the contact surface pressure between the rolling elements 4b in the axially inner row and the outer ring raceway 5b and the inner ring raceway 8b decreases, and relative slippage between the rolling elements 4b and the outer ring raceway 5b and the inner ring raceway 8b becomes more likely to occur, so that transverse waves vibrating in the relative slip direction among the sound waves transmitted from the transmitting probe 22 are less likely to be transmitted to the receiving probe 23 via the rolling elements 4a, 4b and the outer ring 2. For this reason, when the thrust load applied between the outer ring 2 and the hub 3 approaches the predetermined value Fai, the transverse waves transmitted to the auxiliary receiving probe 36 become stronger.

[0147] Therefore, the calculator 24 can perform correction processing such as slowing down the rate at which the pressing force by the load application device 20 increases or shortening the transmission interval by the transmitting probe 22, triggered by a change in the sound waves, such as an increase in the strength of the transverse waves transmitted to the auxiliary receiving probe 36.

[0148] Alternatively or additionally, the signal received by the auxiliary receiving probe 36 can be used directly to determine said predetermined value Fai.

[0149] That is, when the thrust load applied between the outer ring 2 and the hub 3 reaches the predetermined value Fai, the rolling elements 4b in the axially inner row are out of contact with the outer ring raceway 5b or the inner ring raceway 8b, and the amount of sound waves received by the auxiliary receiving probe 36 increases. Therefore, the thrust load applied between the outer ring 2 and the hub 3 at the time when the increase in the amount of sound waves received by the auxiliary receiving probe 36 is detected can be obtained as the predetermined value Fai. Therefore, the preload F0 can be calculated only from the predetermined value Fai obtained using the auxiliary receiving probe 36. Alternatively, the preload F0 can be calculated from both the predetermined value Fai obtained using the auxiliary receiving probe 36 and the predetermined value Fai obtained using the receiving probe 23.

[0150] In this embodiment, the predetermined value Fai can be determined with high accuracy by utilizing the change in sound waves or vibrations received by the auxiliary receiving probe 36 attached to the outer ring 2. Therefore, the load applied to the outer ring 2 and the hub 3 can be reduced, and the preload F0 can be determined with high accuracy.

[0151] The other configurations and effects of the second example are the same as those of the first example.

[0152] [Example 3] A third embodiment of the present disclosure will be described with reference to FIG.

[0153] The preload measuring method for the hub unit bearing 1a of this embodiment is directed to a tapered roller type hub unit bearing 1a that uses tapered rollers as the rolling elements 4c, 4d.

[0154] In the ball bearing type hub unit bearing 1 (see FIG. 1), the rolling elements 4a, 4b, which are balls, can move slightly in the axial direction on the outer ring raceways 5a, 5b and the inner ring raceways 8a, 8b, whereas in the tapered roller bearing type hub unit bearing 1a, the rolling elements 4c, 4d, which are tapered rollers, cannot move in the axial direction on the outer ring raceways 5c, 5d and the inner ring raceways 8c, 8d. Therefore, the positive and negative gaps cannot be measured unless the outer ring 2 and the hub 3 are rotated relative to each other to make the rolling elements 4c, 4d revolve in a spiral shape and are aligned. Therefore, in the preload measurement method of this example, the transmission and reception process S1 is performed while the outer ring 2 and the hub 3 are rotated relative to each other.

[0155] The outer ring support jig 30 constituting the preload measuring device 19b used in this example is configured so as to be rotatable by a drive device (not shown), and is rotatably supported by a thrust bearing 38 with respect to the base 29. However, instead of the outer ring support jig 30, the hub support jig 25 may also be configured so as to be rotatable by a drive device.

[0156] In the preload measurement method of this example, since the rolling elements 4c, 4d are tapered rollers, in the preload calculation process S2, the calculator 24 calculates the preload F0 by substituting the predetermined value Fai obtained in the transmitting and receiving process S1 into the formula 2.

[0157] In the preload measurement method of this example, the transmitting and receiving step S1 is performed while rotating the outer ring 2 and the hub 3 relative to each other, so that a thrust load can be applied between the outer ring 2 and the hub 3 with the rolling elements 4c, 4d aligned. Therefore, the preload applied to the rolling elements 4c, 4d of the tapered roller bearing type hub unit bearing 1a can be found with high accuracy.

[0158] The other configurations and effects of the third example are the same as those of the first example.

[0159] [Example 4] A fourth embodiment of the present disclosure will be described with reference to FIG.

[0160] The preload measuring method for the hub unit bearing 1b in this example is for a hybrid bearing type hub unit bearing 1b that uses balls as the rolling elements 4a in the axial outer row and tapered rollers as the rolling elements 4d in the axial inner row.

[0161] In the hybrid bearing type hub unit bearing 1b, the thrust stiffness of the tapered roller bearing side is sufficiently higher than that of the ball bearing side, so the deformation of the rolling elements 4a, the outer ring raceway 5a, and the inner ring raceway 8a due to the negative gap occurs unevenly on the ball bearing side, which has inferior thrust stiffness. Therefore, if the dimensional variation that contributes to the negative gap on the tapered roller bearing side is not suppressed, the preload applied to the rolling elements 4a (balls) will become excessive, causing a decrease in the life of the hub unit bearing 1b. Alternatively, the preload on the tapered roller bearing side will be insufficient, which is likely to cause inconveniences such as a decrease in the stiffness of the hub unit bearing 1b. Therefore, in the hybrid bearing type hub unit bearing 1b, it is highly necessary to accurately measure the preload applied to the rolling elements 4a, 4d.

[0162] In this example, similarly to the third example, the transmission and reception step S1 is performed while the outer ring 2 and the hub 3 are rotated relative to each other.

[0163] In this example as well, the transmitting and receiving step S1 is performed while rotating the outer ring 2 and the hub 3 relative to each other, so that a thrust load can be applied between the outer ring 2 and the hub 3 with the rolling elements 4d, which are tapered rollers, aligned. Therefore, the preload applied to the rolling elements 4a, 4d of the hybrid type hub unit bearing 1b can be determined with high accuracy.

[0164] When the thrust load applied between the outer ring 2 and the hub 3 is increased, the preload on the ball bearing side, which has low thrust rigidity, increases, so that the thrust load applied between the outer ring 2 and the hub 3 can be reduced. Therefore, damage to the hub unit bearing 1b can be suppressed.

[0165] The other configurations and effects of the fourth example are the same as those of the first and third examples.

[0166] [Example 5] A fifth embodiment of the present disclosure will be described with reference to FIG.

[0167] The preload measuring method for the hub unit bearing 1c of this embodiment is directed to a driving wheel type, multiple row hub unit bearing 1c.

[0168] The outer ring 2a has three rows of outer ring raceways 5e, 5f, and 5g on its inner circumferential surface.

[0169] The hub 3a has three rows of inner ring raceways 8e, 8f, and 8g on its outer circumferential surface.

[0170] The rolling elements 4e, 4f, 4g are balls, and are arranged between three rows of outer ring raceways 5e, 5f, 5g and three rows of inner ring raceways 8e, 8f, 8g, with a plurality of rolling elements in each row being freely rollable.

[0171] In the hub unit bearing 1c of this example, the outermost row rolling element 4e and the innermost row rolling element 4g are provided with a contact angle that results in a back-to-back combination. Also, the intermediate row rolling element 4f, which is disposed in an intermediate row that is located between the outermost row and the innermost row in the axial direction, is provided with a contact angle that results in a back-to-back combination with respect to the outermost row rolling element 4e.

[0172] The outermost row rolling element 4e has a larger diameter than the intermediate row rolling elements 4f and the innermost row rolling elements 4g. The innermost row rolling element 4g has a larger diameter than the intermediate row rolling elements 4f. The pitch circle diameter of the outermost row rolling element 4e is larger than the pitch circle diameter of the intermediate row rolling elements 4f and smaller than the pitch circle diameter of the innermost row rolling element 4g.

[0173] In the drive wheel type hub unit bearing 1c, the hub 3a (hub wheel 14a) which is the drive wheel is configured to be hollow, so the transmitting probe 22 and the receiving probe 23 cannot be brought into contact with the center of the axially outer end face of the hub 3a and the center of the axially inner end face of the hub 3a. For this reason, it is possible to bring one of the transmitting probe 22 and the receiving probe 23 into contact with the axially outer end face of the pilot portion 10, or the other of the transmitting probe 22 and the receiving probe 23 into contact with the axially inner end face of the hub wheel 14a. However, in this case, the circumferential transmission distance of the sound waves or vibrations transmitted from the transmitting probe 22 to the receiving probe 23 becomes longer, making it difficult to distinguish between sound waves due to differences in paths.

[0174] Therefore, in this example, one of the transmitting probe 22 and the receiving probe 23 is abutted against the axially outer end of the hub 3a via an outer mounting jig 39. The outer mounting jig 39 has a disk shape, and has a conical recess 40 in the center of its axially outer surface, for the transmitting probe 22 or the receiving probe 23 to abut against.

[0175] As shown in Fig. 6(A), when an outer mounting jig 39 having an outer diameter smaller than the inner diameter of the pilot portion 10 is used, the axially inner side surface of the outer mounting jig 39 can be brought into contact with a portion (CVJ nut seat surface) of the axially outer end face of the hub 3a that is located radially inner than the pilot portion 10. Alternatively, as shown in Fig. 6(B), when an outer mounting jig 39 having an outer diameter larger than the inner diameter of the pilot portion 10 is used, the axially inner side surface of the outer mounting jig 39 can be brought into contact with the axially outer end face of the pilot portion 10. The transmitting probe 22 or the receiving probe 23 that is brought into contact with the axially outer end face of the hub 3a via the outer mounting jig 39 is disposed on the central axis of the hub 3a.

[0176] In this example, the other of the transmitting probe 22 and the receiving probe 23 is abutted against the axially inner end of the hub 3a via an inner mounting jig 41. The inner mounting jig 41 has a disk shape and has a conical recess 42 in the center of its axially inner surface for abutting the transmitting probe 22 or the receiving probe 23.

[0177] As shown in Fig. 6(A), when an inner mounting jig 41 having an outer diameter smaller than the inner diameter of the inner ring 13 is used, the axially outer side surface of the inner mounting jig 41 can be brought into contact with the axially inner end surface of the hub wheel 14a. Alternatively, as shown in Fig. 6(B), when an inner mounting jig 41 having an outer diameter larger than the inner diameter of the inner ring 13 is used, the axially outer side surface of the inner mounting jig 41 can be brought into contact with the axially inner end surface of the inner ring 13. The transmitting probe 22 or the receiving probe 23 abutted against the axially inner end of the hub 3a via the inner mounting jig 41 is arranged on the central axis of the hub 3a. The transmitting probe 22 and the receiving probe 23 are arranged coaxially.

[0178] In this example, the transmitting probe 22 and the receiving probe 23 are abutted against the axially outer end and axially inner end of the hub 3a using the outer mounting jig 39 and the inner mounting jig 41, so that the transmitting probe 22 and the receiving probe 23 can be arranged coaxially. Therefore, even when the target is a drive wheel type hub unit bearing 1c, the transmission distance of sound waves or vibrations transmitted from the transmitting probe 22 to the receiving probe 23 can be shortened, making it easy to distinguish sound waves due to differences in paths.

[0179] In a multiple-row hub unit bearing, the preload applied to the outer row rolling elements must be higher than the preload applied to the inner row rolling elements. In the case of the hub unit bearing 1c of this example, if the preload applied from the outermost row rolling elements 4e to the middle row rolling elements 4f becomes higher than the preload applied from the outermost row rolling elements 4e to the innermost row rolling elements 4g, the load is concentrated on the middle row rolling elements 4f, which have a lower rated load than the innermost row rolling elements 4g and a shorter application point distance. This leads to a decrease in the bearing life, indentation resistance, and bearing rigidity of the hub unit bearing 1c. Therefore, in the case of the hub unit bearing 1c of this example, the preload applied from the outermost row rolling elements 4e to the innermost row rolling elements 4g must be higher than the preload applied from the outermost row rolling elements 4e to the middle row rolling elements 4f.

[0180] The preload measuring method for the hub unit bearing 1c in this example includes a transmitting and receiving process S1 in which a transmitting probe 22 is abutted against one of the axially outer end and the axially inner end of the hub 3a, and a receiving probe 23 is abutted against the other of the axially outer end and the axially inner end of the hub 3a, and sound waves or vibrations transmitted from the transmitting probe 22 are received by the receiving probe 23 while a thrust load is applied between the outer ring 2a and the hub 3a, and the thrust load is increased and transmission by the transmitting probe 22 and reception by the receiving probe 23 are repeated until a fluctuation is detected in the sound waves or vibrations received by the receiving probe 23.

[0181] Therefore, in the case of a multiple row hub unit bearing 1c, by determining which route the sound waves or vibrations have disappeared, it is possible to measure the preload applied from the outermost row rolling element 4e to the innermost row rolling element 4g, and the preload applied from the outermost row rolling element 4e to the middle row rolling element 4f. Therefore, it is possible to ensure that an appropriate preload is applied to the multiple row hub unit bearing 1c.

[0182] The other configurations and effects of the fifth example are the same as those of the first example.

[0183] Although the first to fifth examples of the embodiment of the present disclosure have been described above, the structures of the first to fifth examples can be appropriately combined and implemented as long as no contradiction occurs. [Explanation of symbols]

[0184] 1, 1a~1c Hub unit bearing 2, 2a Outer ring 3, 3a hub 4a~4g rolling elements 5a~5g Outer raceway 6 Stationary Flange 7 Support hole 8a~8g Inner raceway 9 Rotating flange 10 Pilot Division 11 Mounting hole 12 Stud 13. Inner Circle 14, 14a Hub wheel 15 Small diameter stepped section 16 Step surface 17 Crimping part 18a, 18b retainer 19, 19a, 19b Preload measuring device 20 Load bearing device 21 Load measuring device 22 Outgoing Probe 23 Received Probes 24 Arithmetic unit 25 Hub support jig 26 Insertion hole 27 Through hole 29 Fixed Plate 30 Outer ring support jig 31 Insertion hole 32 Through hole 36 Auxiliary Receiving Probe 38 Thrust bearing 39 Outer mounting fixture 40 Recess 41 Inner mounting jig 42 Recess

Claims

1. an outer ring having a plurality of rows of outer ring raceways on an inner circumferential surface; A hub having a plurality of rows of inner ring raceways on its outer circumferential surface; a plurality of rolling elements, each of which is rollably disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways, and to which a preload is applied; The hub has a hub ring having, on an outer circumferential surface thereof, at least an axially outermost inner ring raceway among the multiple rows of inner ring raceways, and an inner ring having, on an outer circumferential surface thereof, at least an axially innermost inner ring raceway among the multiple rows of inner ring raceways. A method for measuring preload in a hub unit bearing, comprising: a transmitting and receiving process in which a transmitting probe is abutted against one of the axially outer end and the axially inner end of the hub and a receiving probe is abutted against the other of the axially outer end and the axially inner end of the hub, and while a thrust load is applied between the outer ring and the hub, sound waves or vibrations transmitted from the transmitting probe are received by the receiving probe, and the transmission and reception by the receiving probe are repeated while the thrust load is increased continuously or stepwise until a fluctuation is detected in the sound waves or vibrations received by the receiving probe; and a preload calculation step of calculating the preload based on the thrust load applied between the outer ring and the hub at the time when the fluctuation was detected. How to measure preload on hub unit bearings.

2. 2. The method for measuring a preload of a hub unit bearing according to claim 1, wherein in the transmitting and receiving step, the sound waves or the vibrations transmitted from the transmitting probe are received by an auxiliary receiving probe brought into contact with the outer ring.

3. 2. The method for measuring a preload of a hub unit bearing according to claim 1, wherein in the transmitting and receiving step, a change in the number of times the sound waves or vibrations are received by the receiving probe is detected as the fluctuation.

4. 2. The method for measuring a preload of a hub unit bearing according to claim 1, wherein the transmitting and receiving step is performed while rotating the outer ring and the hub relative to each other.

5. an outer ring having a plurality of rows of outer ring raceways on an inner circumferential surface; A hub having a plurality of rows of inner ring raceways on its outer circumferential surface; a plurality of rolling elements, each of which is rollably disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways, and to which a preload is applied; The hub has a hub ring having, on an outer circumferential surface thereof, at least an axially outermost inner ring raceway among the multiple rows of inner ring raceways, and an inner ring having, on an outer circumferential surface thereof, at least an axially innermost inner ring raceway among the multiple rows of inner ring raceways. A preload measuring device for a hub unit bearing, The apparatus includes a load applying device, a load measuring device, a transmitting probe, a receiving probe, and a computing unit, the load applying device applies a thrust load to the hub unit bearing, the load measuring device measures the thrust load pressing the outer ring and the hub from both axial sides, The transmitting probe is connected to a transmitter capable of transmitting sound waves or vibrations, and is in contact with one of an axially outer end and an axially inner end of the hub, the receiving probe is connected to a receiver capable of receiving the sound waves or the vibration and to the computing unit, and is in contact with the other of the axially outer end and the axially inner end of the hub, the computing unit having a function of detecting fluctuations in the sound waves or the vibration received by the receiving probe, and a function of calculating the preload based on the thrust load applied to the outer ring and the hub at the time the fluctuations were detected. A preload measuring device for hub unit bearings.

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