JP2011169720A - Method of measuring pre-load of hub unit bearing for supporting driving wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of measuring pre-load performed while acting shaft force due to nut tightening by fitting a constant velocity joint for a hub unit bearing for supporting a driving wheel with a spline. <P>SOLUTION: A rest wheel 2, a rotating wheel 4 (a hub 10 and an inner composition body 12) rotated by being opposed to and arranged on the rest wheel, and a plurality of rolling bodies 6a, 6b are provided. The hub and the inner wheel composition body fit a fixture 50 forming a spline groove 52 on the outer peripheral part for hub unit bearings A1, A2 for supporting the driving wheel fixed on the constant velocity joint with a tightening member from the end side of a shaft extension direction in a spline hole, fix the fixture on the hub by being tightened with a tightening member 30 from the end side equivalent on the end side of the shaft extension direction, and act shaft force due to the tightening member on the hub unit bearings to give pre-load to measure a pre-load amount while acting the shaft force, while the hub and the inner wheel composition body fit a spline shaft of the constant velocity joint in the spline hole 10t. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement in manufacturing quality of a hub unit bearing for supporting driving wheels of an automobile, and more specifically, to a method for measuring a preload applied to the hub unit bearing.

Bearing units that support automobile wheels (wheel support bearing units) include, for example, the presence and number of flanges of stationary wheels, the presence and number of flanges of rotating wheels (hubs), or the inner ring that constitutes a rotating wheel together with the hub. There are various types (types) depending on the combination of the presence / absence and number of components and the types of rolling elements (balls and various rollers), and the bearing unit is selected according to the usage conditions and purpose of use. ing. These bearing units are used in a state where a preload is applied for the purpose of accurate positioning of the shaft, prevention of shaft runout, improvement of unit rigidity, and the like.
For example, the stationary wheel and the rotating wheel have flanges, and the hub unit bearing in which the rotating wheel is provided with a hub and an inner ring structure, and the hub and the inner ring structure rotate with respect to the stationary wheel has high moment rigidity. The preload is controlled within a very narrow range in order to extend the service life and reduce the torque at the same time.

In the case of a hub unit bearing that supports a driven wheel of an automobile (front wheel of a front engine rear wheel drive (FR) car and rear engine rear wheel drive (RR) car, rear wheel of a front engine front wheel drive (FF) car) In order to prevent the inner ring structure from coming out of the hub during the manufacturing process and at the same time to apply preload to the bearing, the inner ring structure is fixed to the hub by tightening nuts or crimping, and then the preload is measured by various methods. Then, it is shipped to an automobile manufacturer or the like with the set preload amount guaranteed. As an example of the preload measurement method, Patent Document 1 discloses a preload measurement method using a change in rigidity or displacement of a hub unit bearing as a parameter.
The hub unit bearings received at the assembly plant of the automobile manufacturer are left as they are. Since it is mounted on the vehicle by fixing with bolts and nuts, the preload amount guaranteed at the time of setting is supplied to the market and used without changing when the bearing is mounted.

  On the other hand, in the case of a hub unit bearing that supports the driving wheels of an automobile (the rear wheels of an FR vehicle and an RR vehicle, the front wheels of an FF vehicle, and all wheels of a four-wheel drive (4WD) vehicle), the hub unit bearing is After shipment to a manufacturer, etc., the shaft of a constant velocity joint (CVJ: Constant Velocity Joint) is spline-fitted to the inner diameter part (spline hole) of the hub at the assembly plant and fastened to the CVJ with a nut (CVJ nut) Installed in the vehicle. For this reason, due to the expansion of the rolling element raceway surface due to the spline fitting and the axial force due to the nut tightening, the preload of the bearing after being mounted on the vehicle is higher than the set preload amount at the time of shipment.

Japanese Patent No. 3648919

Therefore, in the case of a hub unit bearing for a drive wheel, the preload at the time of shipment from the bearing manufacturer is the state after the shaft of the constant velocity joint is spline fitted to the hub unit bearing and fastened with the CVJ nut. The amount of change (amount of increase) is set so as to obtain an optimal preload amount in step (b).
In particular, in the case of a non-caulking type hub unit bearing (type shown in FIGS. 1, 3 and 5A) to which preload is applied by nut tightening, no axial force is applied at the time of inspection in the manufacturing process. Therefore, the amount of change in the preload is large, and the amount of preload is set to a target value in the vicinity of 0 (zero) preload. For example, a preload measurement method (such as stiffness change or displacement described in Patent Document 1) is set. In the preload measurement method as a parameter, the measurement error may increase depending on the rigidity change or the displacement state.
On the other hand, in the case of a caulking type hub unit bearing (a type shown in FIGS. 2, 4 and 5B) to which preload is applied by caulking, since the axial force due to caulking has already been applied, preloading is performed. However, since the bearing is elastically deformed in the axial direction due to the expansion of the rolling element raceway surface due to spline fitting and the axial force due to the nut tightening, it is difficult to avoid the occurrence of the preload change.

  The present invention has been made to solve such problems, and its purpose is to spline-fit a constant velocity joint to a hub unit bearing for driving wheel support in a manufacturing process and to provide axial force by tightening a nut. An object of the present invention is to provide a method for measuring a preload of a hub unit bearing for supporting a drive wheel, which makes it possible to measure the preload applied to the bearing in an acted state.

  In order to achieve such an object, a preload measurement method for a driving wheel supporting hub unit bearing according to the present invention includes a stationary wheel fixed to a vehicle body component member and maintained in a non-rotating state, a wheel component member and a wheel. A rotation that is composed of a hub fixed to the drive shaft constituent member and at least one inner ring constituent body fixed to the hub, is arranged to face the stationary wheel, and rotates together with the wheel constituent member and the wheel drive shaft constituent member. And a plurality of rolling elements formed on the stationary ring and the rotating ring, respectively, so as to be able to roll between the mutually facing raceway surfaces. With the spline shaft of the constant velocity joint fitted in the spline hole formed in the inner diameter portion of the hub, the shaft is fixed to the constant velocity joint by a fastening member from the end side in the extending direction of the shaft. Measuring the preload of the drive wheel supporting hub unit bearings. At that time, a jig in which a spline groove that can be fitted to the spline hole of the hub is formed in the outer peripheral portion is fitted into the spline hole, and the end of the jig corresponding to the end side in the extending direction of the shaft. The jig is fixed to the hub by fastening with the fastening member from the part side, and the axial force by the fastening member is applied to the hub unit bearing to apply preload to the bearing, and the axial force is applied. Measure the preload in the state of

  In this case, instead of applying an axial force by the fastening member to the hub unit bearing, it is possible to apply a pressing force corresponding to the axial force.

  According to the preload measuring method for a hub unit bearing for driving wheel support of the present invention, a jig (or a spline shaft of an actual machine) having a shape similar to the spline shaft of the constant velocity joint is spline-fitted in the manufacturing process of the bearing. The preload applied to the bearing can be measured in a state where the axial force due to the nut tightening is applied. In other words, the preload can be measured in a state that approximates the state in which the hub unit bearing for driving wheel support is mounted on the automobile, and the preload is measured while avoiding the vicinity of 0 (zero) where the measurement error is large. it can. As a result, it is possible to accurately guarantee the set preload amount for the bearing, and as a result, it is possible to improve the quality of the hub unit bearing for driving wheel support.

It is a mechanism diagram of the preload measuring method according to the first embodiment of the present invention, and is a mechanism diagram in the case of measuring the preload of the non-caulking type drive wheel support hub unit bearing. FIG. 4 is a mechanism diagram of the preload measuring method according to the first embodiment of the present invention, and is a mechanism diagram when measuring a preload of a caulking type driving wheel supporting hub unit bearing. FIG. 6 is a mechanism diagram of a preload measuring method according to a second embodiment of the present invention, and is a mechanism diagram when measuring a preload of a hub unit bearing for driving wheel support of a non-caulking type. FIG. 9 is a mechanism diagram of a preload measuring method according to a second embodiment of the present invention, and is a mechanism diagram when measuring a preload of a caulking type drive wheel supporting hub unit bearing. It is a figure which shows the structure of the hub unit bearing for driving wheel support, Comprising: (a) is a figure which shows a non-caulking type bearing structure, (b) is a figure which shows a caulking type bearing structure.

Hereinafter, a method for measuring a preload of a hub unit bearing for driving wheel support of the present invention (hereinafter also simply referred to as a preload measuring method) will be described with reference to the accompanying drawings.
Drive wheel support hub unit bearings (hereinafter also simply referred to as hub unit bearings or bearings) that are subject to the preload measurement method of the present invention are automobile drive wheels (FR (front engine rear wheel drive)) and RR (rear). It is configured as a bearing unit that supports a rear wheel of a stationary engine rear wheel drive), a front wheel of an FF (front engine front wheel drive) vehicle, and all wheels of a four-wheel drive vehicle.
FIG. 5 shows an example of the configuration of such a hub unit bearing. FIG. 5A shows a non-caulking type hub unit bearing A1 in which the inner ring constituent body 12 is fixed to the hub 10 by tightening a nut. FIG. 2B shows an example of the configuration of a caulking type hub unit bearing A2 in which the inner ring structural body 12 is fixed to the hub 10 by caulking. In the following description, when these hub unit bearings A1 and A2 are mounted on a vehicle, the side corresponding to the outside of the vehicle body (the wheel side (left side in FIG. 5)) is referred to as the outboard side. The opposite side, that is, the side corresponding to the inside of the car body (the right side in the figure) is called the inboard side.

The hub unit bearings A1 and A2 are fixed to a vehicle body constituent member (for example, a knuckle (not shown) of a suspension device) and maintained in a non-rotating state, and are disposed opposite to the stationary wheel 2 so as to constitute a wheel configuration. A member (for example, a wheel disc wheel (not shown)) and a wheel drive shaft component (for example, a constant velocity joint (CVJ) shaft (a component similar to the jig 50 shown in FIGS. 1 to 4) ) And the rotating wheel 4 rotating together with the stationary wheel 2 and the rotating wheel 4 and rolling between the double-row (two rows) raceway surfaces 2s and 4s and between the raceway surfaces 2t and 4t. The rotating wheel 4 includes a hub 10 fixed to the wheel component member and the wheel drive shaft component member, and at least one fixed to the hub 10. Consists of two inner ring components 12 In this case, the hub 10 is formed with a raceway surface 4s opposite to the raceway surface 2s on the outboard side of the stationary wheel 2 on the outer periphery thereof, and the inner ring component 12 has the stationary ring 2 on the outer periphery thereof. A raceway surface 4t facing the raceway surface 2t on the inboard side is formed.
FIG. 5 shows the configuration of the rotating wheel 4 having only one inner ring component 12 and fixing the inner ring component 12 to the inboard side of the hub 10, but includes two inner ring components. Rotating wheels in which raceway surfaces 4t and 4s facing the raceway surfaces 2t and 2s of the stationary ring 2 are formed on these inner ring constituent bodies, and these inner ring constituent bodies are fixed to the inboard side and the outboard side of the hub, respectively. It is also possible to have a configuration of

The rolling elements 6a and 6b roll between the raceway surfaces 2s and 4s and between the raceway surfaces 2t and 4t in a state where the rolling elements 6a and 6b are rotatably held one by one in a pocket formed in the annular cage 8. Thus, the rolling surfaces roll without contact with each other, and as a result, the rolling elements 6a and 6b come into contact with each other to increase friction and prevent seizure. Can do. The hub unit bearings A1 and A2 are preferably filled with a lubricant (for example, grease or lubricating oil) in order to more effectively prevent such an increase in rotational resistance and seizure. .
Note that the rolling elements 6a and 6b may be balls as shown in FIG. 5 or various types of rollers (cylindrical rollers, tapered rollers, spherical rollers, etc.). Moreover, what is necessary is just to apply arbitrary types for the holder | retainer 8 according to the kind of rolling element 6a, 6b. For example, when the rolling element is a ball, types such as an inclined type (Fig. 5), a crown type and a corrugated type can be applied, and the rolling element can be various types of rollers (such as a tapered roller, a cylindrical roller and a spherical roller). In some cases, types such as machined molds, comb molds and basket molds can be applied.

Further, the hub unit bearings A1 and A2 are sealed in a sealed state (airtight state, space inside the unit (a space surrounded by the stationary wheel 2 and the rotating wheel 4 (the hub 10 and the inner ring structural body 12)). Sealing devices 20s and 20t for maintaining the liquid-tight state), thereby preventing foreign matters (for example, muddy water and dust) from entering the inside of the unit and the inside of the unit. The lubricant (for example, grease or lubricating oil) enclosed in the container is prevented from leaking to the outside.
As an example, in the configuration shown in FIG. 5, a contact-type seal (as an example, the whole or a part of a steel bar is connected by various elastic materials to the outboard side of the hub unit bearings A1 and A2. 20s is provided, whereas the inboard side is provided with a package-type seal (pack seal) 20t having a structure in which a seal, a slinger, and a metal core are combined. These seals 20s, 20t By providing the airtightness (air tightness and liquid tightness) inside the unit is maintained. Depending on the type of hub unit bearing, the purpose of use and the conditions of use, etc., the sealing device depends on the level of hermeticity (airtightness and liquid tightness) required in addition to the above. For example, it is possible to arbitrarily select and use a shield formed by pressing a thin metal plate such as a stainless steel plate or an iron plate.

The stationary ring 2 is integrally formed with a fixing flange 2f that protrudes outward (in the direction of increasing the diameter) from the outer peripheral surface 2a, and a fixing bolt (fixed bolt 2h) that penetrates the fixing flange 2f. The stationary wheel 2 can be fixed to a knuckle of a suspension device (not shown) by inserting a screw (not shown) and fastening it to the vehicle body side.
On the other hand, the hub 10 of the rotating wheel 4 is fixed to a disc wheel (not shown) of a wheel via a braking member (for example, a brake disc (not shown)), and is configured to rotate together with the disc wheel. The hub 10 is provided with a hub flange 10f for fixing (externally fitting) a disc portion (not shown) of the disc wheel on the outboard side (left side in FIG. 5) along the circumferential direction. Projected.
The hub 10 has a substantially cylindrical shape having a hole (spline hole) 10t penetrating from one end side to the other end side in the axial direction (from the left end side to the right end side in FIG. 5) at the center thereof. The constant velocity joint shaft (spline shaft) (not shown) is inserted into the spline hole 10t, and the hole 10t and the shaft are fitted to each other (spline fitting). As a result, the hub 10 can rotate together with the shaft.

The hub unit bearings A1 and A2 are fastened from the end in the extending direction of the shaft with the rotating wheel 4 (the hub 10 and the inner ring structure 12) fitted to the hub 10 with the spline shaft of the constant velocity joint. It is fixed to the constant velocity joint by a member (CVJ nut) (corresponding to the nut 30 shown in FIGS. 1 and 2).
In this case, the hub 10 is provided with a CVJ nut seat surface 10c formed by flattening the opening peripheral edge of the spline hole 10t on the outboard side, and the CVJ nut is connected to the end of the shaft in the extending direction side ( The rotating wheel 4 can be positioned and fixed with respect to the shaft by tightening from the left side of FIG. 5 and the lower side of FIG. 1 until it abuts against the CVJ nut seat surface 10c.

At that time, in the case of the non-caulking type hub unit bearing A1 shown in FIG. 5A, a plurality of rolling elements 6a, 6b are held by the cage 8 between the raceway surfaces 2s, 4s and between the raceway surfaces 2t, 4t. In this state, after the inner ring structure 12 is externally fitted to the step portion 10d of the hub 10, the inner ring structure body is sandwiched between the constant velocity joint and the step portion 10d by fastening the CVJ nut. 12 is positioned and fixed with respect to the hub 10. Thereby, the axial force by the CVJ nut is applied, and a predetermined preload is applied to the hub unit bearing A1.
In contrast, in the case of the caulking type hub unit bearing A2 shown in FIG. 5B, a plurality of rolling elements 6a and 6b are held by the cage 8 between the raceway surfaces 2s and 4s and between the raceway surfaces 2t and 4t. After the inner ring constituting body 12 is externally fitted to the stepped portion 10d of the hub 10 in this state, the end portion on the inboard side of the hub 10 is swaged to be sandwiched between the swaged portion 10e and the stepped portion 10d. In this state, the inner ring component 12 is positioned and fixed with respect to the hub 10. Then, the CVJ nut is fastened. Thereby, the axial force by caulking and the axial force by the CVJ nut are applied, and a predetermined preload is applied to the hub unit bearing A2.

  That is, in the non-caulking type hub unit bearing A1, the caulking type hub unit bearing is adjusted by adjusting the magnitude of the axial force (axial force due to nut tightening) caused by the CVJ nut acting on the bearing. In A2, it is possible to set a predetermined preload amount by adjusting the axial force caused by caulking applied to the bearing and the magnitude of the axial force caused by the CVJ nut.

Next, a method for measuring the preload of the hub unit bearings A1 and A2 set in this way will be described.
FIG. 1 and FIG. 2 illustrate a mechanism diagram of the preload measuring method according to the first embodiment of the present invention. FIG. 1 shows a case where the preload of the non-caulking type hub unit bearing A1 is measured. FIG. 2 and FIG. 2 show an example of a mechanism diagram for measuring the preload of the caulking type hub unit bearing A2.
In the present embodiment, a jig 50 (which may be cylindrical or cylindrical) having a spline groove 52 that can be fitted to the spline hole 10t of the hub 10 is formed on the outer periphery of the spline hole 10t. To a predetermined end of the jig 50 (corresponding to the end of the constant velocity joint in the extending direction of the spline shaft). It is fastened by a fastening member (nut (corresponding to the CVJ nut)) 30 from (the lower end side in FIGS. 1 and 2). As a result, the jig 50 is fixed to the hub 10, and the axial force by the nut 30 (in addition to the caulking type hub unit bearing A2 shown in FIG. 2) is applied to the hub unit bearings A1, A2. The preload is applied to the bearings A1 and A2. Then, the preload amount is measured in such a state that the axial force by the nut 30 is applied to the hub unit bearings A1 and A2.

Therefore, in the manufacturing process of these hub unit bearings A1 and A2, the jig 50 is spline-fitted into the spline hole 10t of the hub 10, and the axial force by the nut 30 (axial force by tightening the nut) is applied. The preload applied to the bearings A1 and A2 can be measured. That is, the preload can be measured in a state almost the same as the state in which the hub unit bearings A1 and A2 are mounted on the automobile. In addition, it is not necessary to set the preload amount to the target value near the preload 0 (zero) in anticipation of the amount of change in the preload after mounting on the vehicle, and the preload measurement is avoided avoiding the preload 0 (zero) where the measurement error is large. It can be carried out.
As a result, the amount of change in the preload after the hub unit bearings A1 and A2 are mounted on the automobile can be reduced, and the set preload amount for the bearings A1 and A2 can be accurately guaranteed. As a result, the quality of the hub unit bearings A1 and A2 can be improved.

In this preload measurement, it is possible to use an actual constant velocity joint instead of the jig 50. In this case, the spline shaft of the constant velocity joint is fitted to the hub 10 (spline fitting), and the hub 10 is fastened by a fastening member (CVJ nut) from the end in the extending direction of the shaft. Secure to the speed joint. As a result, as described above, the hub unit bearings A1 and A2 are subjected to the axial force by the CVJ nut (the crimping type hub unit bearing A2 shown in FIG. Is granted. The preload amount may be measured in a state where the axial force by the CVJ nut is applied to the hub unit bearings A1 and A2.
When the axial force from the nut 30 (the CVJ nut) is applied to the hub unit bearings A1 and A2, the nut tightening torque is varied several levels within a predetermined numerical range (from an arbitrarily set minimum value to a maximum value). It is also possible to measure the preload amount in a state in which a level axial force is applied. At that time, the jig 50 or the constant velocity joint of the actual machine is fixed with a predetermined fixing tool (not shown), and the nut 30 (the CVJ nut) is set within the above level with a socket (not shown) for nut tightening. The preload amount may be repeatedly measured while tightening in order from the lower tightening torque. By performing such measurement, it becomes possible to more accurately guarantee the set preload amount for the hub unit bearings A1 and A2 after being mounted on the automobile.

Further, in the manufacturing process of the bearing, there may be restrictions on work that can be performed on the inspection and assembly line. For example, not only using a constant velocity joint of an actual machine, but also fitting of the jig 50 to the hub 10 of the hub unit bearings A1 and A2, fastening of the nut 30, preload measurement, loosening of the nut 30, extraction of the jig 50, etc. There are cases where the series of operations is limited in terms of line configuration, generation of wear powder, damage to the bearing itself, and the like. Further, when the nut tightening is performed by the angle method or the torque gradient method, the screw part is deformed by the tightening, and therefore the nut 30 and the jig 50 cannot be reused. Even when tightening using the torque method, the surface properties and lubrication state (especially the friction coefficient) of the threaded part change each time it is reused, and the same axial force is generated as before even if the same torque is applied again. It becomes impossible to do.
Considering these cases, after the jig 50 (or the constant velocity joint of the actual machine) is spline-fitted to the hub unit bearings A1 and A2, the axial force by the nut 30 (axial force by tightening the nut) is applied. Instead, a pressing force corresponding to the axial force by the nut 30 can be applied to the hub unit bearings A1 and A2. Thus, the preload applied to the bearings A1 and A2 can be measured in a state where a force (pressing force) equivalent to the axial force caused by the nut tightening is applied to the hub unit bearings A1 and A2 without being fastened by the nut 30. It can be performed.

3 and 4 show a mechanism (second embodiment of the present invention) for measuring the preload by applying a force (pressing force Fa shown in the drawing) equivalent to the axial force caused by such nut tightening. FIG. 3 is a diagram illustrating a mechanism for measuring the preload of the non-caulking type hub unit bearing A1, and FIG. 4 illustrates the case of measuring the preload of the caulking type hub unit bearing A2. These mechanism diagrams are shown as examples.
In this case, the hub unit bearings A1 and A2 in a state where the jig 50 is spline-fitted into the spline hole 10t of the hub 10 are fixed to the shaft by the nut tightening by a predetermined pressing means (for example, a hydraulic press). A pressing force Fa having the same magnitude as the force is applied in the same direction as the axial force. At that time, for the non-caulking type hub unit bearing A1 (FIG. 3), the pressing portion 72 of the pressing means 70 is applied to the inboard side end portion (corresponding to the upper end portion in FIG. 3) of the inner ring constituting body 12. The pressing force Fa is applied from the pressing portion 72, and the pressing portion 72 of the pressing means 70 is connected to the inboard side end of the hub 10 with respect to the caulking type hub unit bearing A2 (FIG. 4). The pressing force Fa is applied from the pressing portion 72 so as to abut against the portion (corresponding to the upper end portion in the figure).
In the second embodiment (FIGS. 3 and 4), as described above, the pressing force Fa is directly applied (loaded) to the rotating wheel 4 (the inner ring component 12 or the hub 12) without using the nut 30. Therefore, considering the variation in the yield strength of the nut or the constant velocity joint (spline shaft) thread produced by tightening the nut by the angle method or the torque gradient method, and the variation of the friction coefficient caused by the nut tightening by the torque method, In the axial force range, it is also possible to repeatedly measure the preload amount by applying the pressing force Fa corresponding to several levels of axial force in ascending order. By performing such measurement, it becomes possible to more accurately guarantee the set preload amount for the hub unit bearings A1 and A2 after being mounted on the automobile.

In the preload measurement method according to the first embodiment (FIGS. 1 and 2) and the second embodiment (FIGS. 3 and 4) of the present invention described above, the preload applied to the hub unit bearings A1 and A2 is set. The specific measurement of the amount of preload can be performed as follows.
In the first embodiment (FIGS. 1 and 2), a predetermined oscillator 90 is brought into contact with the nut 30. In the second embodiment (FIGS. 3 and 4), the oscillator 50 is in contact with the jig 50. 90 is abutted. Then, a vibration force having a constant amplitude is generated from the oscillator 90, and vibration is excited in the hub unit bearings A1 and A2 via the nut 30 or the jig 50.
Three vibration detection sensors 92a, 92b, and 92c are attached to the hub unit bearings A1 and A2 as vibration detection means for detecting the excited vibration. These vibration detection sensors 92a, 92b, and 92c are in contact with the inboard side end portions (corresponding to the upper end portions of FIGS. 1 to 4) of the hub unit bearings A1 and A2, and are arranged in a straight line, The detection sensor 92a is positioned on the central axis of the hub 10 (the jig 50), and the vibration detection sensors 92b and 92c are positioned so as to be symmetrical with respect to the vibration detection sensor 92a with the central axis in between. And the vibration excited by hub unit bearing A1, A2 is detected, and the detected waveform is output as a voltage signal.

The output signals of the vibration detection sensors 92b and 92c are amplified by the corresponding addition amplifiers 94b and 94c, added in time series by the adder 95, amplified by the main amplifier 96, and then input to the high-pass filter 98. On the other hand, the output signal of the vibration detection sensor 92a is amplified by the main amplifier 96a and then input to the high pass filter 98a.
The high-pass filters 98 and 98a cut frequency components below the measurement frequency band (that is, vibration components that cause external noise) from the input signals.
Output signals from the high-pass filters 98 and 98a are input to the arithmetic processing unit 100. The arithmetic processing unit 100 uses Fast Fourier Transform (FFT) to eliminate the in-phase component included in the output signals from the high-pass filters 98 and 98a, and the resonance frequency (specificity of the hub unit bearings A1 and A2). Frequency) and the resonance frequency (natural frequency) is converted into the bearing stiffness values of the hub unit bearings A1 and A2.

If such a bearing rigidity value is obtained, the set preload amount of the preload applied to the hub unit bearings A1 and A2 can be obtained using the bearing rigidity value as a power meter (for details, refer to the “NSK report issued by the applicant”. "See the description of the November 1989 issue, pages 59-66, etc.).
In the first embodiment (FIGS. 1 and 2) and the second embodiment (FIGS. 3 and 4), the preload is measured in a state similar to the state in which the hub unit bearings A1 and A2 are mounted on the automobile. Since the preload can be measured while avoiding the vicinity of 0 (zero) preload with a large measurement error, even when the preload measurement using the bearing stiffness value as a parameter as described above is performed. The measurement error can be reduced.

2 Stationary wheel 4 Rotating wheel 6a, 6b Rolling element 10 Hub 10t Spline hole 12 Inner ring component 30 Fastening member (nut)
50 Jig 52 Spline groove A1, A2 Hub unit bearing for driving wheel support

Claims (2)

A stationary wheel fixed to the vehicle body component and maintained in a non-rotating state;
The wheel component member and the wheel drive shaft component member, and at least one inner ring component body fixed to the hub, are arranged to face the stationary wheel, and the wheel component member and the wheel drive shaft configuration A rotating wheel that rotates with the member;
A plurality of rolling elements formed on the stationary wheels and the rotating wheels, respectively, and incorporated so as to roll between the mutually facing raceway surfaces,
The hub of the rotating wheel and the inner ring constituting body are formed by the fastening member from the extending direction end portion side of the shaft in a state where the spline shaft of the constant velocity joint is fitted in the spline hole formed in the inner diameter portion of the hub. A preload measurement method for a hub unit bearing for driving wheel support fixed to a constant velocity joint,
A jig in which a spline groove that can be fitted with the spline hole of the hub is formed in the outer peripheral portion is fitted into the spline hole, and the end side of the jig corresponding to the end side in the extending direction of the shaft is inserted. A state in which the jig is fixed to the hub by fastening with the fastening member, and an axial force by the fastening member is applied to the hub unit bearing to apply a preload to the bearing, and the axial force is applied. A preload measuring method for a hub unit bearing for supporting a drive wheel, characterized in that a preload amount is measured at   2. The preload of the hub unit bearing for driving wheel support according to claim 1, wherein a pressing force corresponding to the axial force is applied to the hub unit bearing instead of an axial force by the fastening member. Measuring method.

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