JP2008292276A - Load measuring instrument for rolling bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a load measuring instrument for a rolling bearing unit for supporting a wheel, manufactured at low cost. <P>SOLUTION: The present invention provides the rolling bearing unit 1 for supporting the wheel, and the load measuring instrument 2. The load measuring instrument 2 is provided with a permanent magnet 14, at least one pair of sensors 15a, 15b, and a computer. A magnetic attractive state of the permanent magnet 14 is uniform as to a rotational direction. The respective sensors 15a, 15b are installed in detecting parts thereof respectively with magnetic detecting elements of changing a characteristic in response to a change of a density of a passing magnetic flux. The computer finds a direction and a level of a radial load acting between an outer ring 3 and a hub 4, based on output signals from the both sensors 15a, 15b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  A load measuring device for a rolling bearing unit for supporting a wheel according to the present invention rotatably supports a wheel of an automobile with respect to a suspension device, measures the direction and magnitude of a radial load applied to the wheel, and Used to contribute to stable operation.

  Conventionally, an antilock brake system (ABS), a traction control system (TCS), and an electronically controlled vehicle stability control system (ESC) have been widely used as devices for ensuring the running stability of a vehicle. In order to configure these travel stabilization devices, a plurality of state quantities such as wheel rotational speed, acceleration applied to the vehicle body, and yaw moment are measured by separate sensors and sent to a single controller. The controller controls the output of the engine according to each state quantity, and controls the braking force of each wheel in association with each other (however, depending on the braking force depending on the case).

  In order to further improve the performance of the travel stabilization device as described above, it is considered effective to measure the load applied to each wheel. For example, it is considered that the running stability of the vehicle can be further improved by measuring the radial load applied to each wheel and adjusting the braking force of each wheel according to the distribution of the radial load related to each wheel. . Conventionally, for example, those described in Patent Documents 1 to 4 are known as load measuring devices for rolling bearing units that can be used for such running stabilization.

  Among these, in the load measuring apparatus described in Patent Document 1, the radial relative relationship between the outer ring and the hub, which is a pair of bearing ring members constituting the wheel bearing rolling bearing unit, is detected by a non-contact displacement sensor. Measure the displacement. Based on the relative displacement amount, a radial load applied between the outer ring and the hub is obtained.

  Moreover, in the load measuring apparatus described in Patent Document 2, a detection object having an L-shaped cross section is externally fixed to a hub constituting a wheel bearing rolling bearing unit, and the axial side surface and the outer peripheral surface of the detection object are fixed. In addition, the detection part of the sensor supported and fixed to the outer ring is opposed to the outer ring. Then, the radial relative displacement amount between the outer ring and the hub is measured by the sensor, and the radial load applied between the outer ring and the hub is obtained based on the relative displacement amounts in both directions. .

  Moreover, in the load measuring apparatus described in patent document 3, the revolution speed of the rolling element which comprises the rolling bearing unit for wheel support and is arrange | positioned in a double row is measured with a pair of sensor. And based on the difference which exists between the revolution speeds of these rolling elements of a both row | line | column, the radial load added between the outer ring | wheel and hub which comprise the said wheel support rolling bearing unit is calculated | required.

  Further, in the load measuring device described in Patent Document 4, a detection unit of a pair of sensors is provided on a detection surface of a special encoder in which a phase whose characteristics change is gradually changed in accordance with an action direction of a load to be measured. Are opposed to each other in the state of being separated in this direction of action. And based on the phase difference which exists between the output signals of both these sensors, the radial load added between the outer ring and the hub which comprise the rolling bearing unit for wheel support is calculated | required. Further, the above-mentioned Patent Document 4 has a structure in which the detection unit of one sensor is opposed to the detection surface of a special encoder in which the pitch at which the characteristics change is gradually changed corresponding to the direction of the load to be measured. It is also described. In the case of such a structure, the radial load applied between the outer ring and the hub constituting the wheel support rolling bearing unit is obtained based on the change in the duty ratio of the output signal of the sensor.

  In the case of the conventional load measuring device as described in Patent Documents 1 to 4 described above, an expensive non-contact displacement sensor is used (in the case of the invention described in Patent Documents 1 and 2). Or using a special encoder (in the case of the inventions described in Patent Documents 3 and 4), the cost increases. In particular, when a permanent magnet encoder is used to reduce the size of the sensor, it is difficult to accurately regulate the magnetized region of the encoder, which causes a significant increase in cost.

JP 2001-21577 A JP 2004-45219 A JP-A-2005-331496 JP 2006-1113017 A

  The present invention has been invented to realize a load measuring device for a wheel bearing rolling bearing unit that can be manufactured at low cost in view of the above-described circumstances.

The load measuring device for a wheel supporting rolling bearing unit of the present invention includes a wheel supporting rolling bearing unit and a load measuring device.
Of these, the rolling bearing unit for supporting a wheel has a double row outer ring raceway on the inner peripheral surface, and has an outer ring that does not rotate even in use, and a double row inner ring raceway on the outer peripheral surface, and combines the wheels in use. A hub that is fixed and rotates together with the wheels, and a plurality of rolling elements provided between the inner ring raceways in both rows and the outer ring raceways in both rows are provided.
The load measuring device is supported at least by a permanent magnet supported and fixed at the axial inner end of the hub and a part of an inner surface of a cover fitted and fixed at the axial inner end of the outer ring. A pair of sensors and an arithmetic unit are provided.
The permanent magnet has at least an outer peripheral surface that is a cylindrical surface concentric with the hub, and has a constant magnetization state in the rotation direction.
In addition, each of the sensors is provided with a magnetic detection element that changes its characteristics in response to a change in the density of the magnetic flux passing therethrough in each detection unit. This magnetic detection element is a Hall element (including a Hall IC), for example, as described in claim 2. Of the sensors, a pair of sensors is supported on a part of the inner surface of the cover. And each detection part is made to oppose this permanent magnet in the mutually opposite position regarding the radial direction of the said permanent magnet. The direction in which the paired sensors are arranged in this way (the direction in which the paired sensors are separated) is the acting direction of the radial load to be measured.
The computing unit determines the direction and magnitude of the radial load acting between the outer ring and the hub based on the output signals of the sensors arranged in opposite positions with respect to the radial direction of the permanent magnet and paired with each other. Ask.

  In the case of the rolling bearing unit load measuring device of the present invention configured as described above, it can be manufactured at low cost. That is, the shape and magnetization pattern of the permanent magnet having the detected surface is simple, and the processing (magnetization work) of the permanent magnet is facilitated, so that the manufacturing cost of the load measuring device including the permanent magnet can be kept low. .

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention. The load measuring device for a rolling bearing unit of this example includes a wheel bearing rolling bearing unit 1 and a load measuring device 2.
Among these, the wheel-supporting rolling bearing unit 1 includes an outer ring 3 and a hub 4 arranged concentrically with each other, and a plurality of rolling elements 5 and 5. Of these, the outer ring 3 has an outward flange-shaped mounting portion 6 on the outer peripheral surface, and double-row outer ring raceways 7 and 7 on the inner peripheral surface. Such an outer ring 3 does not rotate with the mounting portion 6 fixed to the suspension device in use. Further, the hub 4 is the outer end in the axial direction of the outer peripheral surface ("outside" with respect to the axial direction means the side on the outer side in the width direction of the vehicle body when attached to the suspension device, opposite to the left side in FIG. In addition, the side that is the central side in the width direction of the vehicle body when attached to the suspension device is referred to as “inside” with respect to the axial direction (the same applies throughout the present specification and claims). The coupling flange 8 is provided with double-row inner ring raceways 9, 9 at the axially intermediate portion or the axially inner end portion, respectively. Then, a plurality of rolling elements 5 and 5 are held between the inner ring raceways 9 and 9 and the outer ring raceways 7 and 7 by a plurality of cages 10 and 10 in both rows. It is provided freely. Furthermore, the axially outer end side opening of the internal space 11 in which the rolling elements 5 and 5 are installed is closed by a seal ring 12 fitted into the axially outer end of the outer ring 3. Further, the inner end in the axial direction of the outer ring 3 is closed by a cover 13 formed in a bottomed cylindrical shape by, for example, drawing a metal plate.

  The load measuring device 2 includes a permanent magnet 14, two pairs of pairs, a total of four sensors 15 a to 15 d, and a calculator (not shown). Of these, the permanent magnet 14 is formed in a disk shape as a whole so that its outer peripheral surface is a cylindrical surface and is magnetized in the axial direction. Therefore, the magnetized state of the permanent magnet 14 is constant with respect to the rotation direction. Such a permanent magnet 14 is supported and fixed concentrically with the hub 4 by bonding or the like on the inner end face in the axial direction of the hub 4 so as to be rotatable together with the hub 4.

The sensors 15 a to 15 d are supported and fixed to the inner surface of the bottom plate portion 16 constituting the cover 13 via a substrate 17. In the case of this example, it is intended to measure the radial load in the vertical direction (Z-axis direction) and the radial load in the front-rear direction (X-axis direction). For this reason, among the sensors 15a to 15d, the pair of sensors 15a and 15b constituting the first set is sandwiched between the inner surface of the bottom plate portion 16 and the permanent magnet 14 from both the upper and lower directions (however, the upper and lower It is not necessary to overlap in the direction). On the other hand, the pair of sensors 15c and 15d constituting the second set is sandwiched from both the front and rear directions in the inner surface of the bottom plate portion 16 (however, it is not necessary to overlap in the front and rear direction). It is supported and fixed in position. Each of these sensors 15a to 15d incorporates a Hall element, which is a magnetic detection element that changes characteristics in response to changes in the density of magnetic flux passing through, in each detection unit. To output a changing signal. In such detection portions of the sensors 15a to 15d, that is, the Hall element, a radial load does not act between the outer ring 3 and the hub 4, and the outer ring 3 and the hub 4 are relatively displaced in the radial direction. In a neutral state, it exists on a single virtual circle centered on the central axis of the permanent magnet 14. That is, in the neutral state, the center position of the Hall element incorporated in each of the sensors 15a to 15d in the radial direction of the permanent magnet 14 is positioned on a single virtual circle centered on the central axis of the permanent magnet 14. I am letting.
Further, the arithmetic unit is incorporated in a controller such as ABS, TCS, ESC, etc. provided on the vehicle body side, and based on the output signals of the sensors 15a to 15d, the outer ring 3, the hub 4, The radial load acting in the vertical direction and the front-rear direction is calculated.

  According to the load measuring device of the wheel supporting rolling bearing unit of the present example configured as described above, the radial load applied to the wheel supporting rolling bearing unit provided between each wheel and the suspension device as follows. Is required. First, when this radial load is applied, the outer ring 3 and the hub 4 are relatively displaced in the radial direction based on elastic deformation of the rolling elements 5 and 5 and the outer ring and inner ring raceways 7 and 9. . And the position of the outer peripheral surface of the said permanent magnet 14 and the position of the detection part of each said sensors 15a-15d are relatively displaced regarding the radial direction of the said outer ring | wheel 3. FIG. On the other hand, the distribution of the density of magnetic flux entering and exiting between the axial end surfaces of the permanent magnet 14 remains constant when viewed with the permanent magnet 14 as a reference. Therefore, the magnetic flux density at the detection unit of each of the sensors 15 a to 15 d changes with relative displacement between the outer ring 3 and the hub 4. And the output signal of each said sensors 15a-15d changes with the change of this magnetic flux density.

For example, consider a case where a large radial load is applied to the outer ring 3 from the vehicle body side and the outer ring 3 is displaced downward in FIG. In this case, the distance in the radial direction of the outer ring 3 between the detection unit of the upper sensor 15a and the outer peripheral surface of the permanent magnet 14 out of the pair of sensors 15a and 15b arranged above and below is reduced. In contrast, the distance in the radial direction of the outer ring 3 between the detection portion of the lower sensor 15b and the outer peripheral surface of the permanent magnet 14 increases. As a result, the level of the output signal of the upper sensor 15a increases (or decreases), and at the same time, the level of the output signal of the lower sensor 15b decreases (or increases). For this reason, based on the output signals (difference) of the pair of sensors 15 a and 15 b, the relative displacement amount between the outer ring 3 and the hub 4, and therefore, acts between the outer ring 3 and the hub 4. Radial load is required. Note that the relationship between the change amount of the difference between the output signals of the pair of sensors 15a and 15b and the magnitude of the radial load is obtained in advance by experiment or calculation, and is incorporated in the software installed in the arithmetic unit. deep. The radial load in the front-rear direction can be obtained by the same processing based on the output signals of the pair of sensors 15c, 15d arranged in the front-rear direction.
In the case of the rolling bearing unit load measuring device of this example configured as described above and acting as described above, it can be manufactured at low cost for the reasons described above.

[Second Example of Embodiment]
4 to 5 show a second example of the embodiment of the present invention. In the case of this example, the permanent magnet 14a is formed in an annular shape, and the permanent magnet 14a is magnetized in the radial direction. The magnetization direction is constant over the entire circumference. Even in the structure of this example, radial loads in the vertical direction and the front-rear direction can be obtained in the same manner as in the first example.
In the case of carrying out the present invention, only one pair of sensors may be provided if only a radial load in one direction (for example, the vertical direction or the front-rear direction) is required.

Sectional drawing which shows the 1st example of embodiment of this invention. The X section enlarged view of FIG. The figure seen from the left side of FIG. The figure similar to FIG. 2 which shows the 2nd example of embodiment of this invention. The figure seen from the left of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling bearing unit for wheel support 2 Load measuring device 3 Outer ring 4 Hub 5 Rolling body 6 Mounting part 7 Outer ring raceway 8 Coupling flange 9 Inner ring raceway 10 Cage 11 Internal space 12 Seal ring 13 Cover 14, 14a Permanent magnet 15a, 15b, 15c, 15d sensor 16 bottom plate portion 17 substrate

Claims (2)

A wheel bearing rolling bearing unit and a load measuring device;
Of these, the rolling bearing unit for supporting a wheel has a double row outer ring raceway on the inner peripheral surface, and has an outer ring that does not rotate even in use, and a double row inner ring raceway on the outer peripheral surface, and combines the wheels in use. A hub that is fixed and rotates with the wheels, and a plurality of rolling elements provided between each of the inner ring raceways in both rows and the outer ring raceways in both rows,
The load measuring device includes at least a pair of permanent magnets supported and fixed to the inner end of the hub in the axial direction and a part of an inner surface of a cover fitted and fixed to the inner end of the outer ring in the axial direction. Sensor and a computing unit,
The permanent magnet has at least an outer peripheral surface as a cylindrical surface concentric with the hub, and a constant magnetization state in the rotation direction.
Each of the sensors is provided with a magnetic detection element that changes characteristics in response to a change in the density of magnetic flux passing through each detection unit, and is supported on a part of the inner surface of the cover, Corresponding to the direction of action of the radial load to be measured, the respective detection parts are opposed to the permanent magnet at opposite positions with respect to the radial direction of the permanent magnet,
The computing unit determines the direction and magnitude of the radial load acting between the outer ring and the hub based on the output signals of the sensors arranged in opposite positions with respect to the radial direction of the permanent magnet and paired with each other. Ask,
Load measuring device for wheel bearing rolling bearing unit.   The load measuring device for a wheel bearing rolling bearing unit according to claim 1, wherein the magnetic detection element is a Hall element.

Images